 Patent Application Title |
Patent App Num. |
Date |
| Liquid crystal optical device configured to reduce polarization dependent loss and polarization mode dispersion | 20100302469 | 20101202 |
| An LC-based optical device compensates for differences in optical path lengths of polarization components of input beam. As a result, PDL and PMD of the optical device are reduced. The compensation mechanism may be a glass plate that is disposed in an optical path of a polarization component so that the optical path length of that polarization component can be made substantially equal to the optical path length of the other polarization component that traverses through a half-wave plate. Another compensation mechanism is a birefringent displacer that has two sections sandwiching a half-wave plate, wherein the two sections are of different widths and the planar front surface of the birefringent displacer can be positioned to be non-orthogonal with respect to the incident input light beam.
... |
| Polarization controller and polarization mode dispersion compensator | 20100296152 | 20101125 |
| A polarization controller includes a first polarization controller, a demultiplexer, a second polarization controller, and a multiplexer. The first polarization controller controls the state of polarization of input light such that a part of the wavelength components of the input light is in a first state of polarization. The demultiplexer demultiplexes the light output from the first polarization controller into a plurality of wavelength components. The second polarization controller controls the plurality of wavelength components in a second state of polarization by using liquid crystal modulation devices. The multiplexer multiplexes the plurality of wavelength components output from the second polarization controller.
... |
| In-service optical network testing | 20100272431 | 20101028 |
| A system may include a first measurement device configured to be coupled to a first node in an optical path being measured. The first measurement device may be configured to generate a signal at an initiating device; identify an unused channel in an optical path, wherein the optical path includes at least two spans; and transmit the signal on the unused channel. A second test device may be configured to be coupled to a last node in the optical path being measured. The second measurement device may be configured to: receive the signal at a destination device; compensate the signal for chromatic dispersion (CD) and/or polarization mode dispersion (PMD) effects; and determine CD and/or PMD measurements associated with the optical path being measured based on the... |
| Single-polarization high power fiber lasers and amplifiers | 20100260214 | 20101014 |
| A novel polarization maintaining optical fiber, which can be used as a high-power polarization maintaining fiber laser or amplifier, is described. Insensitivity of the polarization state to external fiber bending and temperature changes is accomplished by minimizing polarization mode-coupling via reducing stresses inside the fiber core via increasing the fiber diameter. Alternatively, polarization mode-coupling can be minimized by an optimization of the fiber coating to minimize stresses at the interface between the fiber and the coating. As a result insensitivity to polarization mode-coupling is obtained at greatly reduced values of birefringence compared to small-diameter fibers. The fiber is of significant use in any application where polarization stability is important, and will be useful in telecommunications applications in particular for reducing polarization mode dispersion. An implementation in... |
| Pmdc feedback arrangement for apol-dpsk | 20100247109 | 20100930 |
| Methods and apparatus are provided for optical polarization mode dispersion compensator (PMDC) feedback control for APol-DPSK signals. A feedback signal generator includes a delay-line-interferometer (DLI), with a differential delay line delay (D) different from one bit period (Tb). In an exemplary embodiment, the DLI delay is in the range of 0.5 Tb<D<1.0 Tb, or 1.0 Tb<D<1.5 Tb, preferably 0.85 Tb or 1.15 Tb. The DLI is coupled to a single-ended detector, whose output is amplified and bandpass filtered around the frequency of half the bit rate. The filtered signal is then applied to an RF power detector to generate the PMDC feedback signal. Generation of the PMDC feedback signal in accordance with the present invention is insensitive to any alignment of the state of polarization (SOP)... |
| |
| Polarization mode emulators and polarization mode dispersion compensators based on optical polarization rotators with discrete polarization states | 20100239245 | 20100923 |
| Systems, devices and techniques for generating and analyzing states of polarization in light using multiple adjustable polarization rotators having different discrete polarization rotation states in various applications.
... |
| Polarization mode dispersion suppressing method and polarization mode dispersion suppressing apparatus | 20100221018 | 20100902 |
| A polarization mode dispersion (PMD) suppressing apparatus wherein a first polarization controller adjusts a polarization of an input signal, thereby generating a first polarization adjusted signal; a variable DGD compensator gives a DGD to the first polarization adjusted signal, thereby generating a first PMD compensated signal; a second polarization controller adjusts a polarization of the first PMD compensated signal, thereby generating a second polarization adjusted signal; a polarization beam splitter produces a higher-order PMD suppressed signal forming one of two orthogonal components of the second polarization adjusted signal and a monitor signal forming the other component; an intensity detector generates an optical carrier intensity signal reflecting the intensity of an optical carrier wavelength component; and a control signal generator controls the first polarization controller, etc., based... |
| Polarization mode dispersion (pmd) compensation in polarization multiplexed coded orthogonal frequency division multiplexing (ofdm) systems | 20100215371 | 20100826 |
| A receiver and method are provided. The receiver includes a detector configured to receive polarization multiplexed coded orthogonal frequency division multiplexing input sequences and generate estimates of unknown transmitted symbols in the input sequences for x- and y-polarization channels with respect to laser phase noise and PMD. A demapper coupled to the detector is configured to partially cancel polarization mode dispersion (PMD) in the input sequences by computing symbol probabilities for the estimates with respect to the laser phase noise, and averaging the symbol probabilities with respect to the laser phase noise. One or more low-density parity-check (LDPC) decoders coupled to the demapper are configured to receive bit probabilities derived from the averaged symbol probabilities and output code words based at least on the bit probabilities.... |
| Optical waveguide device, manufacturing method therefor, optical modulator, polarization mode dispersion compensator, and optical switch | 20100195953 | 20100805 |
| An optical waveguide device includes: a substrate which has an electro-optical effect; an optical waveguide which is formed on the substrate and/or inside the substrate; and an in-substrate electrode which is formed of a metal and provided inside the substrate.
... |
| Method of controlling longitudinal properties of optical fiber | 20100148383 | 20100617 |
| A method of creating optical fiber to exhibit predetermined length-dependent characteristics (e.g., chromatic dispersion, polarization mode dispersion, cutoff wavelength, birefringence) includes the steps of: characterizing the fiber's selected characteristic(s) as a function of length; and performing a “treatment” which modifies the refractive index over the given length to adjust the defined parameter to fall within a defined tolerance window. These steps may be repeated one or more times until the measure of the parameter falls with the defined tolerance limits. The treatment process may include, for example, a low energy actinic radiation exposure, anneal, mechanical strain, DC voltage, plasma application, etc. Indeed, if the treatment process is repeated, a different technique may be used to adjust the refractive index (“different” processes include, for example, modifying the... |
| Method for increasing accuracy of measurement of mean polarization mode dispersion | 20100134788 | 20100603 |
| The present invention provides a method of determining a mean differential group delay associated with a length of optical fiber. The method including measuring a magnitude of a polarization mode dispersion vector as a function of frequency, using a frequency-domain polarization mode dispersion measurement apparatus, where the magnitude of the polarization mode dispersion vector is a scalar differential group delay. Also the method calculates a frequency derivative of the scalar differential group delay from the magnitude of the polarization mode dispersion vector to obtain a first result. The frequency derivative of the scalar differential group delay being a scalar second-order polarization mode dispersion function. The method further multiplies a proportionality coefficient B2 by the first result to calculate the mean differential group delay. Also, the method... |
| Adaptive frequency domain equalization without cyclic prefixes | 20100119241 | 20100513 |
| Polarization multiplexing, optical communications systems can suffer from chromatic dispersion and polarization mode dispersion, resulting in channel delay spread. These errors can be compensated quickly and simply in the frequency domain. By obviating the need for a cyclic prefix, the complexity of the equalization can be reduced by more than a factor of twenty.
... |
| Enhanced polarization mode dispersion of optical channels | 20100119224 | 20100513 |
| A device receives, from an optical receiver, performance information associated with an optical channel generated by an optical transmitter, and determines, based on the received performance information, a wavelength that minimizes polarization mode dispersion (PMD) associated with the optical channel. The device also provides, to the optical transmitter, a request to adjust an optical channel wavelength to the determined wavelength.
... |
| |
| Polarization mode dispersion compensation and polarization demultiplexing systems and methods for optical transmission systems | 20100111530 | 20100506 |
| The present disclosure provides polarization mode dispersion compensation (PMDC) and polarization de-multiplexing systems and methods for polarization multiplexed (PolMux) optical transmission systems. The PMDC detects an error signal before a polarization splitter in PolMux systems for controlling polarization controllers (PC) and/or DGDs in the PMDC for return-to-zero (RZ) differential m-phase shift keying (DmPSK) signals. For bit-aligned PolMux systems, the error signal could be the level of clock frequency at one, two, or more times of the baud rate at one polarization. For bit-interleaved PolMux systems, the error signal could be the level of clock frequency at two times of the baud rate at one polarization. The PMDC can operate in PolMux systems with any arbitrary time offset between the two polarizations. The polarization de-multiplexer utilizes error... |
| Method and apparatus for determining differential group delay and polarization mode dispersion | 20100073667 | 20100325 |
| A method and apparatus for measuring at least one polarization-related characteristic of an optical path (FUT) uses an optical source means connected to the FUT at or adjacent a proximal end of the FUT and an analyzing-and-detection unit connected to the FUT at or adjacent its proximal or distal end. The optical source means injects into the FUT at least partially polarized light having a controlled state of polarization (I-SOP). The analyzer-and-detection unit extracts corresponding light from the FUT, analyzes and detects the extracted light corresponding to at least one transmission axis (A-SOP), and processes the corresponding electrical signal to obtain transmitted coherent optical power at each wavelength of light in each of at least two groups of wavelengths, wherein the lowermost (λl) and uppermost (λU)... |
| Method and system for a polarization mode dispersion tolerant optical homodyne detection system with optimized transmission modulation | 20100046957 | 20100225 |
| An optical homodyne communication system and method in which a side carrier is transmitted along with data bands in an optical data signal, and upon reception, the side carrier is boosted, shifted to the center of the data bands, and its polarization state is matched to the polarization state of the respective data bands to compensate for polarization mode dispersion during transmission. By shifting a boosted side carrier to the center of the data bands, and by simultaneously compensating for the effects of polarization mode dispersion, the provided system and method simulate the advantages of homodyne reception using a local oscillator. The deleterious effects of chromatic dispersion on the data signals within the data bands are also compensated for by applying a corrective function to the... |
| Optical transmission system and optical transmission control method | 20100021169 | 20100128 |
| The present invention is intended to provide an optical transmission system which is applicable not only to a known signal but also to an unknown signal, and has a high reliability at a low cost. A branching device branches an optical transmission output of a transmitter, and transmits the branched signals through different optical transmission channels. A polarization mode dispersion monitor monitors the degree of polarization mode dispersion from the optical transmission channels at the receiving end. A switch control circuit and a switch select a signal which is less affected by a deterioration in quality due to polarization mode dispersion, and outputs the selected signal to receiver 8. In this way, the probability of a deterioration in the quality of a signal due to polarization... |
| Arrangement for adjusting and compensating for first- and second-order polarization mode dispersion | 20100007952 | 20100114 |
| A configuration contains a series connection of a first emulation element, having a first adjustable differential delay time between the fast and slow main axes and further having an adjustable chromatic dispersion of a polarization adjuster for the adjustment of a polarization rotation angle, and of a second emulation element, having a second adjustable delay time. Advantageously, the first and second differential delay times, the polarization rotation angle, and the chromatic dispersion can be adjusted by the configuration such that a desired value each is obtained for the differential group delay, the depolarization, and the polarization-dependant chromatic dispersion. By the adjustment of the chromatic dispersion, arbitrary frequency-dependant run times of the spectral components of a broadband optical input signal are generated. The configuration may also be... |
| Liquid crystal optical device configured to reduce polarization dependent loss and polarization mode dispersion | 20100302469 | 20101202 |
| An LC-based optical device compensates for differences in optical path lengths of polarization components of input beam. As a result, PDL and PMD of the optical device are reduced. The compensation mechanism may be a glass plate that is disposed in an optical path of a polarization component so that the optical path length of that polarization component can be made substantially equal to the optical path length of the other polarization component that traverses through a half-wave plate. Another compensation mechanism is a birefringent displacer that has two sections sandwiching a half-wave plate, wherein the two sections are of different widths and the planar front surface of the birefringent displacer can be positioned to be non-orthogonal with respect to the incident input light beam.
... |
| Polarization controller and polarization mode dispersion compensator | 20100296152 | 20101125 |
| A polarization controller includes a first polarization controller, a demultiplexer, a second polarization controller, and a multiplexer. The first polarization controller controls the state of polarization of input light such that a part of the wavelength components of the input light is in a first state of polarization. The demultiplexer demultiplexes the light output from the first polarization controller into a plurality of wavelength components. The second polarization controller controls the plurality of wavelength components in a second state of polarization by using liquid crystal modulation devices. The multiplexer multiplexes the plurality of wavelength components output from the second polarization controller.
... |
| In-service optical network testing | 20100272431 | 20101028 |
| A system may include a first measurement device configured to be coupled to a first node in an optical path being measured. The first measurement device may be configured to generate a signal at an initiating device; identify an unused channel in an optical path, wherein the optical path includes at least two spans; and transmit the signal on the unused channel. A second test device may be configured to be coupled to a last node in the optical path being measured. The second measurement device may be configured to: receive the signal at a destination device; compensate the signal for chromatic dispersion (CD) and/or polarization mode dispersion (PMD) effects; and determine CD and/or PMD measurements associated with the optical path being measured based on the... |
| Single-polarization high power fiber lasers and amplifiers | 20100260214 | 20101014 |
| A novel polarization maintaining optical fiber, which can be used as a high-power polarization maintaining fiber laser or amplifier, is described. Insensitivity of the polarization state to external fiber bending and temperature changes is accomplished by minimizing polarization mode-coupling via reducing stresses inside the fiber core via increasing the fiber diameter. Alternatively, polarization mode-coupling can be minimized by an optimization of the fiber coating to minimize stresses at the interface between the fiber and the coating. As a result insensitivity to polarization mode-coupling is obtained at greatly reduced values of birefringence compared to small-diameter fibers. The fiber is of significant use in any application where polarization stability is important, and will be useful in telecommunications applications in particular for reducing polarization mode dispersion. An implementation in... |
| Pmdc feedback arrangement for apol-dpsk | 20100247109 | 20100930 |
| Methods and apparatus are provided for optical polarization mode dispersion compensator (PMDC) feedback control for APol-DPSK signals. A feedback signal generator includes a delay-line-interferometer (DLI), with a differential delay line delay (D) different from one bit period (Tb). In an exemplary embodiment, the DLI delay is in the range of 0.5 Tb<D<1.0 Tb, or 1.0 Tb<D<1.5 Tb, preferably 0.85 Tb or 1.15 Tb. The DLI is coupled to a single-ended detector, whose output is amplified and bandpass filtered around the frequency of half the bit rate. The filtered signal is then applied to an RF power detector to generate the PMDC feedback signal. Generation of the PMDC feedback signal in accordance with the present invention is insensitive to any alignment of the state of polarization (SOP)... |
| Polarization mode emulators and polarization mode dispersion compensators based on optical polarization rotators with discrete polarization states | 20100239245 | 20100923 |
| Systems, devices and techniques for generating and analyzing states of polarization in light using multiple adjustable polarization rotators having different discrete polarization rotation states in various applications.
... |
| Polarization mode dispersion suppressing method and polarization mode dispersion suppressing apparatus | 20100221018 | 20100902 |
| A polarization mode dispersion (PMD) suppressing apparatus wherein a first polarization controller adjusts a polarization of an input signal, thereby generating a first polarization adjusted signal; a variable DGD compensator gives a DGD to the first polarization adjusted signal, thereby generating a first PMD compensated signal; a second polarization controller adjusts a polarization of the first PMD compensated signal, thereby generating a second polarization adjusted signal; a polarization beam splitter produces a higher-order PMD suppressed signal forming one of two orthogonal components of the second polarization adjusted signal and a monitor signal forming the other component; an intensity detector generates an optical carrier intensity signal reflecting the intensity of an optical carrier wavelength component; and a control signal generator controls the first polarization controller, etc., based... |
| Polarization mode dispersion (pmd) compensation in polarization multiplexed coded orthogonal frequency division multiplexing (ofdm) systems | 20100215371 | 20100826 |
| A receiver and method are provided. The receiver includes a detector configured to receive polarization multiplexed coded orthogonal frequency division multiplexing input sequences and generate estimates of unknown transmitted symbols in the input sequences for x- and y-polarization channels with respect to laser phase noise and PMD. A demapper coupled to the detector is configured to partially cancel polarization mode dispersion (PMD) in the input sequences by computing symbol probabilities for the estimates with respect to the laser phase noise, and averaging the symbol probabilities with respect to the laser phase noise. One or more low-density parity-check (LDPC) decoders coupled to the demapper are configured to receive bit probabilities derived from the averaged symbol probabilities and output code words based at least on the bit probabilities.... |
| Optical waveguide device, manufacturing method therefor, optical modulator, polarization mode dispersion compensator, and optical switch | 20100195953 | 20100805 |
| An optical waveguide device includes: a substrate which has an electro-optical effect; an optical waveguide which is formed on the substrate and/or inside the substrate; and an in-substrate electrode which is formed of a metal and provided inside the substrate.
... |
| Method of controlling longitudinal properties of optical fiber | 20100148383 | 20100617 |
| A method of creating optical fiber to exhibit predetermined length-dependent characteristics (e.g., chromatic dispersion, polarization mode dispersion, cutoff wavelength, birefringence) includes the steps of: characterizing the fiber's selected characteristic(s) as a function of length; and performing a “treatment” which modifies the refractive index over the given length to adjust the defined parameter to fall within a defined tolerance window. These steps may be repeated one or more times until the measure of the parameter falls with the defined tolerance limits. The treatment process may include, for example, a low energy actinic radiation exposure, anneal, mechanical strain, DC voltage, plasma application, etc. Indeed, if the treatment process is repeated, a different technique may be used to adjust the refractive index (“different” processes include, for example, modifying the... |
| Method for increasing accuracy of measurement of mean polarization mode dispersion | 20100134788 | 20100603 |
| The present invention provides a method of determining a mean differential group delay associated with a length of optical fiber. The method including measuring a magnitude of a polarization mode dispersion vector as a function of frequency, using a frequency-domain polarization mode dispersion measurement apparatus, where the magnitude of the polarization mode dispersion vector is a scalar differential group delay. Also the method calculates a frequency derivative of the scalar differential group delay from the magnitude of the polarization mode dispersion vector to obtain a first result. The frequency derivative of the scalar differential group delay being a scalar second-order polarization mode dispersion function. The method further multiplies a proportionality coefficient B2 by the first result to calculate the mean differential group delay. Also, the method... |
| Adaptive frequency domain equalization without cyclic prefixes | 20100119241 | 20100513 |
| Polarization multiplexing, optical communications systems can suffer from chromatic dispersion and polarization mode dispersion, resulting in channel delay spread. These errors can be compensated quickly and simply in the frequency domain. By obviating the need for a cyclic prefix, the complexity of the equalization can be reduced by more than a factor of twenty.
... |
| Enhanced polarization mode dispersion of optical channels | 20100119224 | 20100513 |
| A device receives, from an optical receiver, performance information associated with an optical channel generated by an optical transmitter, and determines, based on the received performance information, a wavelength that minimizes polarization mode dispersion (PMD) associated with the optical channel. The device also provides, to the optical transmitter, a request to adjust an optical channel wavelength to the determined wavelength.
... |
| Polarization mode dispersion compensation and polarization demultiplexing systems and methods for optical transmission systems | 20100111530 | 20100506 |
| The present disclosure provides polarization mode dispersion compensation (PMDC) and polarization de-multiplexing systems and methods for polarization multiplexed (PolMux) optical transmission systems. The PMDC detects an error signal before a polarization splitter in PolMux systems for controlling polarization controllers (PC) and/or DGDs in the PMDC for return-to-zero (RZ) differential m-phase shift keying (DmPSK) signals. For bit-aligned PolMux systems, the error signal could be the level of clock frequency at one, two, or more times of the baud rate at one polarization. For bit-interleaved PolMux systems, the error signal could be the level of clock frequency at two times of the baud rate at one polarization. The PMDC can operate in PolMux systems with any arbitrary time offset between the two polarizations. The polarization de-multiplexer utilizes error... |
| Method and apparatus for determining differential group delay and polarization mode dispersion | 20100073667 | 20100325 |
| A method and apparatus for measuring at least one polarization-related characteristic of an optical path (FUT) uses an optical source means connected to the FUT at or adjacent a proximal end of the FUT and an analyzing-and-detection unit connected to the FUT at or adjacent its proximal or distal end. The optical source means injects into the FUT at least partially polarized light having a controlled state of polarization (I-SOP). The analyzer-and-detection unit extracts corresponding light from the FUT, analyzes and detects the extracted light corresponding to at least one transmission axis (A-SOP), and processes the corresponding electrical signal to obtain transmitted coherent optical power at each wavelength of light in each of at least two groups of wavelengths, wherein the lowermost (λl) and uppermost (λU)... |
| Method and system for a polarization mode dispersion tolerant optical homodyne detection system with optimized transmission modulation | 20100046957 | 20100225 |
| An optical homodyne communication system and method in which a side carrier is transmitted along with data bands in an optical data signal, and upon reception, the side carrier is boosted, shifted to the center of the data bands, and its polarization state is matched to the polarization state of the respective data bands to compensate for polarization mode dispersion during transmission. By shifting a boosted side carrier to the center of the data bands, and by simultaneously compensating for the effects of polarization mode dispersion, the provided system and method simulate the advantages of homodyne reception using a local oscillator. The deleterious effects of chromatic dispersion on the data signals within the data bands are also compensated for by applying a corrective function to the... |
| Optical transmission system and optical transmission control method | 20100021169 | 20100128 |
| The present invention is intended to provide an optical transmission system which is applicable not only to a known signal but also to an unknown signal, and has a high reliability at a low cost. A branching device branches an optical transmission output of a transmitter, and transmits the branched signals through different optical transmission channels. A polarization mode dispersion monitor monitors the degree of polarization mode dispersion from the optical transmission channels at the receiving end. A switch control circuit and a switch select a signal which is less affected by a deterioration in quality due to polarization mode dispersion, and outputs the selected signal to receiver 8. In this way, the probability of a deterioration in the quality of a signal due to polarization... |
| Arrangement for adjusting and compensating for first- and second-order polarization mode dispersion | 20100007952 | 20100114 |
| A configuration contains a series connection of a first emulation element, having a first adjustable differential delay time between the fast and slow main axes and further having an adjustable chromatic dispersion of a polarization adjuster for the adjustment of a polarization rotation angle, and of a second emulation element, having a second adjustable delay time. Advantageously, the first and second differential delay times, the polarization rotation angle, and the chromatic dispersion can be adjusted by the configuration such that a desired value each is obtained for the differential group delay, the depolarization, and the polarization-dependant chromatic dispersion. By the adjustment of the chromatic dispersion, arbitrary frequency-dependant run times of the spectral components of a broadband optical input signal are generated. The configuration may also be... |
| Optical communications system having chromatic dispersion and polarization mode dispersion compensation | 20090304391 | 20091210 |
| Described are an optical communications system and a method that allow for compensation of chromatic dispersion and polarization mode dispersion imparted to a communications signal propagating through an optical link. The system is based on a cost-effective optical transport architecture that accommodates baud rates exceeding 15 Gbaud and eliminates the need for costly optical dispersion compensators. Compensation for polarization mode dispersion is performed at the receiver using nonlinear processing. Advantageously, direct detection modulation using inexpensive electro-optic system components can be used in place of more costly and complex coherent and differential modulation formats. Digital filtering can be performed at the transmitter and the input signal can be inverted based on the nonlinearity of the transmitter electro-optic components. Consequently, the bandwidth and linearity requirements for the transmitter... |
| Polarization mode dispersion compensation in multilevel coded-modulation schemes using blast algorithm and iterative polarization cancellation | 20090297144 | 20091203 |
| Receivers and methods are provided for polarization mode dispersion compensation in multi-level coded-modulation schemes using a BLAST algorithm and iterative polarization cancellation. A receiver includes a vertical Bell Laboratories Layered Space-Time Architecture (V-BLAST) orthogonal frequency division multiplexing (OFDM) detector configured to receive input sequences and partially cancel polarization interference with respect to the input sequences to output symbol estimates for the input sequences. The receiver further includes one or more low-density parity-check (LDPC) decoders coupled to the V-BLAST OFDM detector configured to receive channel bit reliabilities and output code words. The channel bit reliabilities are indirectly calculated from the symbol estimates. The one or more LDPC decoders iteratively provide extrinsic soft information feedback to the V-BLAST OFDM detector to compensate for the polarization interference.
... |
| Polarization mode dispersion compensation | 20090285582 | 20091119 |
| An apparatus and method for correcting for the polarization mode distortion of an optical signal is described. The optical data signal to be transmitted is processed by a switch configured to place the signal into a plurality of polarization states on a periodic basis. At the receiving end of the system, a portion to the signal is coupled to a polarimeter and the wavelength-dependent state of polarization (SOP) of the received signal determined for the plurality of polarization states imposed on the transmitted signal. The data for two of the transmitted polarization states is selected to be used as the basis for correcting the SOP so as to compensate for the wavelength dependence thereof. The corrections may be applied in an optical pulse shaper.
... |
| Systems and methods for the mitigation of polarization mode dispersion impairments in fiber optic links | 20090279900 | 20091112 |
| The present invention provides systems and methods for the mitigation of PMD impairments in fiber optic links. The present invention utilizes synchronous polarization modulation and digital control of polarization modulation, instead of independent polarization modulators and analog control used in the current state of art. Also, the present invention utilizes a feedback loop to avoid identified bad polarization states instead of a random open loop operation. Further, the present invention includes a mechanism to continually update polarization states based on pre-corrected FEC error analysis from data receivers. Additionally, the present invention includes a mechanism for collecting and correlating error feedback signals from multiple geographically-diverse network nodes. Advantageously, the present invention provides a cost-effective and efficient way to implement mitigation of PMD impairments, while using only a... |
| Systems and methods for the mitigation of polarization mode dispersion impairments in fiber optic links | 20090279900 | 20091112 |
| The present invention provides systems and methods for the mitigation of PMD impairments in fiber optic links. The present invention utilizes synchronous polarization modulation and digital control of polarization modulation, instead of independent polarization modulators and analog control used in the current state of art. Also, the present invention utilizes a feedback loop to avoid identified bad polarization states instead of a random open loop operation. Further, the present invention includes a mechanism to continually update polarization states based on pre-corrected FEC error analysis from data receivers. Additionally, the present invention includes a mechanism for collecting and correlating error feedback signals from multiple geographically-diverse network nodes. Advantageously, the present invention provides a cost-effective and efficient way to implement mitigation of PMD impairments, while using only a... |
| Polarization mode dispersion measurement using an improved fixed analyzer method | 20090268198 | 20091029 |
| A device for performing polarization mode dispersion (PMD) measurements of an optical fiber is disclosed. The PMD measurement device employs a fixed analyzer method, and includes a tunable Fabry-Perot inferometer as the wavelength-selective element and an optical bandpass filter for spectrum calibration. A novel scanning algorithm, which performs multiple scans at different velocities, enables accurate PMD measurements, even of moving optical cable. The tunable Fabry-Perot interferometer is able to scan over a wide wavelength range and yet have a narrow linewidth, such that a wide range of PMD values can be measured.
... |
| Polarization mode dispersion measurement using an improved fixed analyzer method | 20090268198 | 20091029 |
| A device for performing polarization mode dispersion (PMD) measurements of an optical fiber is disclosed. The PMD measurement device employs a fixed analyzer method, and includes a tunable Fabry-Perot inferometer as the wavelength-selective element and an optical bandpass filter for spectrum calibration. A novel scanning algorithm, which performs multiple scans at different velocities, enables accurate PMD measurements, even of moving optical cable. The tunable Fabry-Perot interferometer is able to scan over a wide wavelength range and yet have a narrow linewidth, such that a wide range of PMD values can be measured.
... |
| Method and apparatus for compensating for polarization mode dispersion (pmd) | 20090252497 | 20091008 |
| Current optical networks are engineered to handle amplifier noise and chromatic dispersion. Polarization mode dispersion occurs in optical networks due splitting of the light energy of a pulse propagating in a fiber into two modes. Compensating for polarization mode dispersion is a difficult and expensive task and hence only few commercial systems have been deployed to deal with this issue. A polarization mode dispersion compensation module according to an example embodiment of the present invention compensates for polarization mode dispersion by determining a performance metric related to an error rate of an optical signal in at least one polarization mode in a filtered state. Based on the performance metric, a control vector is determined to control the optical signal in the at least one polarization mode... |
| Method and apparatus for compensating for polarization mode dispersion (pmd) | 20090252497 | 20091008 |
| Current optical networks are engineered to handle amplifier noise and chromatic dispersion. Polarization mode dispersion occurs in optical networks due splitting of the light energy of a pulse propagating in a fiber into two modes. Compensating for polarization mode dispersion is a difficult and expensive task and hence only few commercial systems have been deployed to deal with this issue. A polarization mode dispersion compensation module according to an example embodiment of the present invention compensates for polarization mode dispersion by determining a performance metric related to an error rate of an optical signal in at least one polarization mode in a filtered state. Based on the performance metric, a control vector is determined to control the optical signal in the at least one polarization mode... |
| Polarization optical time domain reflectometer and method of determining pmd | 20090244522 | 20091001 |
| In a method of measuring cumulative polarization mode dispersion (PMD) along the length of a fiber-under-test (FUT), a polarization-sensitive optical time domain reflectometer (POTDR) is used to inject into the FUT plural series of light pulses arranged in several groups. Each group comprises at least two series of light pulses having different but closely-spaced wavelengths and the same state of polarization (SOP). At least two, and preferably a large number of such groups, are injected and corresponding OTDR traces obtained for each series of light pulses by averaging the impulse-response signals of the several series of light pulses in the group. The process is repeated for a large number of groups having different wavelengths and/or SOPs. The PMD then is obtained by normalizing the OTDR traces... |
| Selecting wavelengths and routes in an optical network | 20090214202 | 20090827 |
| Selecting a wavelength and a route includes facilitating communication through routes among nodes. Each route is associated with a plurality of wavelengths and comprises one or more segments that couple one node to another node. A polarization mode dispersion value is determined for each wavelength of each route to yield polarization mode dispersion values for each route. A wavelength and a route are selected according to the polarization mode dispersion values.
... |
| Selecting wavelengths and routes in an optical network | 20090214202 | 20090827 |
| Selecting a wavelength and a route includes facilitating communication through routes among nodes. Each route is associated with a plurality of wavelengths and comprises one or more segments that couple one node to another node. A polarization mode dispersion value is determined for each wavelength of each route to yield polarization mode dispersion values for each route. A wavelength and a route are selected according to the polarization mode dispersion values.
... |
| Selecting wavelengths and routes in an optical network | 20090214202 | 20090827 |
| Selecting a wavelength and a route includes facilitating communication through routes among nodes. Each route is associated with a plurality of wavelengths and comprises one or more segments that couple one node to another node. A polarization mode dispersion value is determined for each wavelength of each route to yield polarization mode dispersion values for each route. A wavelength and a route are selected according to the polarization mode dispersion values.
... |
| Selecting wavelengths and routes in an optical network | 20090214202 | 20090827 |
| Selecting a wavelength and a route includes facilitating communication through routes among nodes. Each route is associated with a plurality of wavelengths and comprises one or more segments that couple one node to another node. A polarization mode dispersion value is determined for each wavelength of each route to yield polarization mode dispersion values for each route. A wavelength and a route are selected according to the polarization mode dispersion values.
... |
| Selecting wavelengths and routes in an optical network | 20090214202 | 20090827 |
| Selecting a wavelength and a route includes facilitating communication through routes among nodes. Each route is associated with a plurality of wavelengths and comprises one or more segments that couple one node to another node. A polarization mode dispersion value is determined for each wavelength of each route to yield polarization mode dispersion values for each route. A wavelength and a route are selected according to the polarization mode dispersion values.
... |
| Method and apparatus for the production of optical fibers with reduced polarization mode dispersion | 20090205374 | 20090820 |
| A method and apparatus for manufacturing an optical fiber includes the steps and/or means of: drawing a fiber from a heated preform by applying a pulling force to the fiber; spinning the fiber while it is drawn, wherein the step of spinning the fiber includes the sub-steps of winding the fiber on a spin roller by a winding arc, such that a friction force is generated between the fiber and the spin roller resulting from the winding arc and from the pulling force; axially displacing the spin roller such that the fiber is caused to roll over the spin roller surface by the friction force.
... |
| Method and apparatus for the production of optical fibers with reduced polarization mode dispersion | 20090205374 | 20090820 |
| A method and apparatus for manufacturing an optical fiber includes the steps and/or means of: drawing a fiber from a heated preform by applying a pulling force to the fiber; spinning the fiber while it is drawn, wherein the step of spinning the fiber includes the sub-steps of winding the fiber on a spin roller by a winding arc, such that a friction force is generated between the fiber and the spin roller resulting from the winding arc and from the pulling force; axially displacing the spin roller such that the fiber is caused to roll over the spin roller surface by the friction force.
... |
| Method and arrangement for polarization mode dispersion mitigation | 20090190930 | 20090730 |
| In an optical transmission system including a transmitter Tx and a receiver Rx connected via a fiber link F, where the receiver Rx is adapted to utilize Forward Error Correction (FEC) on received signals, a polarization scrambler is provided at the transmitter Tx to scramble the polarization state of a transmitted signal, a polarization delay line is provided at the receiver Rx for controlling the polarization mode dispersion induced distortion of a received signal, a feedback unit is provided at the receiver Rx for providing a feedback signal based on at least part of the received signal, and at least one polarization controller interconnects the fiber link F and the polarization delay line. The power controller is operable based on the feedback signal to mitigate the... |
| Optical fiber for amplification | 20090185263 | 20090723 |
| Provided is an erbium doped optical fiber (EDF) for amplification which allows an easy estimation of the amplification performance and high production stability. The fiber includes a core and a cladding. The core is mainly made of silica glass and doped with erbium at a concentration of 500 wtppm or more and 2500 wtppm or less. In the fiber, the cutoff wavelength is 850 nm or more and 1450 nm or less, the mode field diameter is 4.5 μm or more and 6.5 μm or less, the polarization mode dispersion is not more than 0.1 ps per 10 m, the coordination number of oxygen elements around an erbium element in the core is one or more and eight or less, and the bond length between erbium... |
| Polarization mode dispersion compensation using bcjr equalizer and iterative ldpc decoding | 20090177945 | 20090709 |
| A turbo equalizer includes a Bahl-Cocke-Jelinek-Raviv (BCJR) equalizer configured to receive a transmitted signal and partially cancel inter-symbol interference (ISI) due to polarization-mode dispersion (PMD). A low-density parity check (LDPC) decoder is coupled to the BCJR equalizer to receive channel bit reliabilities therefrom. The LDPC decoder iteratively provides extrinsic soft information feedback to the BCJR equalizer to compensate for PMD.
... |
| Polarization mode dispersion compensation circuit | 20090162068 | 20090625 |
| An object of the present invention is to realize a compensation circuit which can cope with rapidly fluctuating polarization mode dispersion, and the configuration thereof is a polarization dispersion compensation circuit for compensating polarization mode dispersion which takes place when a signal propagates on a transmission path, characterized by comprising: a front-end compensation part configured as a transversal filter for shaping a waveform subjected to polarization mode dispersion; and a data tracking/recovery part including a PLL-type data recovery circuit having a loop frequency band higher than the fluctuation frequency of polarization mode dispersion, and that tracks the temporal fluctuation of the polarization mode dispersion to recover data.
... |
| Polarization mode dispersion compensation circuit | 20090162068 | 20090625 |
| An object of the present invention is to realize a compensation circuit which can cope with rapidly fluctuating polarization mode dispersion, and the configuration thereof is a polarization dispersion compensation circuit for compensating polarization mode dispersion which takes place when a signal propagates on a transmission path, characterized by comprising: a front-end compensation part configured as a transversal filter for shaping a waveform subjected to polarization mode dispersion; and a data tracking/recovery part including a PLL-type data recovery circuit having a loop frequency band higher than the fluctuation frequency of polarization mode dispersion, and that tracks the temporal fluctuation of the polarization mode dispersion to recover data.
... |
| Method and system for polarization mode dispersion compensation | 20090142071 | 20090604 |
| The invention relates to a method and a system for controlling a PMD compensator (2). For this purpose, a measuring signal (MS) is branched off from an already compensated optical data signal (ODSK) and supplied to a polarization adjuster (2). The output signal of the latter is supplied to an optical filter unit (61) and subdivided into two optical measuring signal components (OMKI, OMK2) having different polarizations. After a respective opto-electrical conversion, the spectra are compared with each other in an analysis and control unit (81) and the PMD compensator (2) is adjusted in such a manner that they are as identical as possible.
... |
| Method for reducing the uncertainty of the measured average pmd of a long fiber | 20090135408 | 20090528 |
| A methodology, device and memory medium for measuring the polarization mode dispersion (PMD) of an optical fiber is disclosed. The root mean square (rms) differential group delay (DGD) of fiber sections is estimated, the multisection DGD value τΣ is calculated, and a determination is made as to how much the value τΣ is likely to differ from the true mulitsection rms value τΣrms.
... |
| Method and device for measuring polarization state and polarization mode dispersion in photonic transmission systems | 20090109437 | 20090430 |
| From the analysis the variation in the polarization state versus frequency is calculated, as well as its associate PMD vector and the DGD present in the signal transmitted. This information may be used as a control signal for a PMD compensator device in order to upgrade the quality of communication in the system.
... |
| Polarization mode dispersion compensation | 20090087193 | 20090402 |
| Methods and systems for PMD compensation in an optical communication system are implemented by transmitting multiple optical signals through a common optical conduit to an optical compensator that adjustably rotates the polarization states of the multiple optical signals and transmits the rotated optical signals to an optical receiver. The receiver, upon sensing an excessive error condition, commands the optical compensator to change the polarization state of rotation, which changes the PMD profile of the received optical signals.
... |
| Polarization mode dispersion compensation using an arrayed waveguide grating | 20090080072 | 20090326 |
| One embodiment of the present invention sets forth a system for compensating for the detrimental effects of all-order polarization mode dispersion. The system includes a broadband polarization correction module cascaded with a broadband phase correction module. Each of the modules includes an AWG chip as a wavelength dispersing element, as opposed to a bulk optic grating. Thus, aligning the optical components used to separate light beams of different wavelengths within the system is simpler, and the size of the overall system is reduced. Further, the AWG chip may be more easily aligned with the other optical components within the system, with the alignment being more robust, both mechanically and thermally, relative to prior art systems that include bulk optics. Since AWG chips may be fabricated using... |
| Systems and methods for polarization mode dispersion mitigation | 20090080883 | 20090326 |
| In one exemplary embodiment, a method comprises transmitting an optical signal via the optical line, measuring a relative change in spectral intensity of the optical signal near a clock frequency (or half of that frequency) while varying a polarization of the optical signal between a first state of polarization and a second state of polarization, and using the relative change in spectral intensity of the optical signal to determine and correct the DGD of the optical line. Another method comprises splitting an optical signal traveling through the optical line into a first and second portions having a first and second principal states of polarization of the optical line, converting the first and second portions into a first and second electrical signals, delaying the second electrical signal... |
| Systems and methods for polarization mode dispersion mitigation | 20090073560 | 20090319 |
| In one exemplary embodiment, a method comprises transmitting an optical signal via the optical line, measuring a relative change in spectral intensity of the optical signal near a clock frequency (or half of that frequency) while varying a polarization of the optical signal between a first state of polarization and a second state of polarization, and using the relative change in spectral intensity of the optical signal to determine and correct the DGD of the optical line. Another method comprises splitting an optical signal traveling through the optical line into a first and second portions having a first and second principal states of polarization of the optical line, converting the first and second portions into a first and second electrical signals, delaying the second electrical signal... |
| In-service optical dispersion determining system and method | 20090060523 | 20090305 |
| A system and method for in-service optical dispersion determination are provided. Optical dispersion is determined by splitting a first optical signal into two components, introducing a time delay between the two components such that corresponding pulses of the two components partially overlap, combining the two components to generate a combined optical signal comprising a first component and a second component, determining power of the combined optical signal while applying a plurality of dispersion compensation values, in order to determine a dispersion compensation value that results in a minimum detected power of the combined optical signal. Polarization Mode Dispersion is determined by adjusting the time delay that is introduced until the power of the combined optical signal is substantially equal for all of the plurality of dispersion... |
| Polarization mode dispersion analyzer | 20080297768 | 20081204 |
| A polarization mode dispersion analyzer having a light source, a sensor, an output phase signal analyzer, and a controller. The light source generates a probe light signal that is intensity modulated and also polarization modulated, the light source being adapted to apply the light signal to a device under test. The sensor generates an output phase signal related to the phase of the intensity modulation of an output optical signal leaving the device under test. The output phase signal analyzer measures an amplitude and phase of at least one frequency component of the output phase signal at a frequency related to the polarization modulation. The controller generates a signal indicative of a differential group delay of the device under test utilizing the measured amplitude and phase.... |
| Optical transmitter, optical network and method for compensation of polarization mode dispersion | 20080292321 | 20081127 |
| An optical transmitter apparatus for use in an optical communications network has a polarization dithering unit, an optical transmitter unit, and a transmission fiber. The polarization dithering unit is connected in series between an output of the optical transmitter unit and the transmission fiber.
... |
| Methods and systems for polarization control and polarization mode dispersion compensation for wideband optical signals | 20080212980 | 20080904 |
| An optical processing method includes: receiving an optical signal from an optical system, wherein the optical signal is distorted by frequency-dependent polarization effects in the optical system; spatially dispersing frequency components of the distorted optical signal on a spatial light modulator (SLM); and independently adjusting the polarization transfer matrix of multiple regions of the SLM to reduce the distortion of the optical signal. A related optical processing method includes: providing a precompensation signal indicative of frequency-dependent polarization effects in a downstream optical system; spatially dispersing frequency components of an optical signal on a spatial light modulator (SLM); and independently adjusting the polarization transfer matrix of multiple regions of the SLM to at least partially precompensate the optical signal for distortions caused by the frequency-dependent polarization effects... |
| Method and apparatus for dynamic polarization mode dispersion compensation | 20080205814 | 20080828 |
| A method and a system for dynamic compensating polarization mode dispersion (PMD) in an optical communication system. An optical input signal passes through a compensating element first. A splitting device taps a fraction of the optical input signal and sends it to a monitoring element with birefringence properties. The monitoring element separates the fraction into two split signals with orthogonal principal states of polarization. The split signals are detected at photodetectors. An optimised coefficient is obtained from the detected split signals, and used to calculate an angle between a fast axis of the monitoring element and the fast axis of the optical fiber. The compensating element is set according to the determined angle to compensate the PMD. One or both of the monitoring element and the... |
| Optical fiber ribbon core and optical fiber cable | 20080181565 | 20080731 |
| There are provided an optical fiber ribbon and optical fiber cable which suppress the deterioration of polarization mode dispersion and contribute to the increase of communication capacity in wavelength division multiplexing. An optical fiber ribbon includes a plurality of optical fibers 12 tied in a bundle and a ribbon coating layer 13 formed around the plurality of optical fibers to integrate the plurality of optical fibers, wherein the glass-transition temperature of the coating ranges from 80° C. to 130° C. and “a” is 0.01 mm2 or less, where “a” is a sectional area of the ribbon coating layer 13 in a cross section in which outer half of the optical fiber at an edge of the ribbon and the coating of the optical fiber ribbon... |
| Polarization mode dispersion compensator, polarization mode dispersion compensating method, and its application to optical communication system | 20080159739 | 20080703 |
| The present invention provides a polarization mode dispersion compensator comprising: a compensating portion which includes a first polarization controller which performs polarization conversion on light propagating along an optical transmission line and a DGD (Differential Group Delay) emulator which adds a DGD to the light which is polarization-converted by said first polarization controller, said compensating portion being for compensating polarization mode dispersion which occurs in the light while the light propagates along the optical transmission line; a second polarization controller for performing polarization conversion on the light, of which the polarization mode dispersion is compensated, so that a state of polarization of the light can be one linear polarization; a polarization beam splitting portion for splitting the light, which is polarization-converted by said second polarization controller,... |
| System, method and apparatus for polarization mode dispension compensation and demultiplexing polarization multiplexed signals | 20080159741 | 20080703 |
| A polarization multiplex transmission system (10) comprises two optical signals (z1, z2) transmitted over the same optical fibre (15) at the same wavelength but with orthogonal polarizations. The system is characterised by receiving apparatus (10) which is operable to filter the two components with orthogonal polarization of the signal received in accordance with an appropriate transfer matrix which is dynamically controlled on the basis of the output signals in such a manner as to approximate the reverse transfer matrix of the fibre in the region of the spectrum occupied by the signal so as to compensate for Polarization Mode Dispersion (PMD) and polarization rotation introduced by the fibre and eliminating distortion and mutual interference effects for both the signals and thereby obtain a demultiplexed output corresponding... |
| Methods and systems for controlling fiber polarization mode dispersion (pmd) | 20080151232 | 20080626 |
| A method is provided for predicting an installed performance parameter of an optical fiber cable. The method includes obtaining a measurement indicative of a value of the performance parameter at a first moment in time. A measurement indicative of a value of the performance parameter at a second moment in time may then be obtained. A first correlation may then be determined between the measurement at the first moment in time and the measurement at the second moment in time. A value of the performance parameter at the second moment in time may then be estimated based upon the measurement at the first moment in time in combination with the first correlation, the first correlation being based upon observations of a manner in which the performance... |
| Reduction of signal degradations in optical transmission links | 20080124091 | 20080529 |
| Methods, devices and/or systems are provided for reducing signal degradations in optical transmission links. A means for ensuring a flexible manipulation for the improvement of an optical signal, especially during operation, is provided in a simple and cost-effective manner. To this end, a signal degradation in an optical transmission link is reduced by at least partially compensating a chromatic dispersion and a polarization mode dispersion of an optical signal, by adapting the temperature of a dispersion compensation device coupled into the transmission link.
... |
| Optical signal processing apparatus, optical signal transmission system and optical signal processing method | 20080107425 | 20080508 |
| Influence of polarization mode dispersion, occurring in an optical fiber is mitigated by means of polarization scrambling, differential group delay which a received optical signal has is optically suppressed; the optical signal in which differential group delay is thus suppressed is converted into an electric signal; and error correcting processing is carried out on the electric signal obtained, a jitter amplitude in the received optical signal is suppressed, influence of which to a jitter tolerance increases due to increase in speed of the polarization scrambling.
... |
| Polarization-sensitive optical time domain reflectometer and method for determining pmd | 20080100828 | 20080501 |
| In a method of measuring cumulative polarization mode dispersion (PMD) along the length of a fiber-under-test (FUT), a polarization-sensitive optical time domain reflectometer (POTDR) is used to inject into the FUT plural series of light pulses arranged in several groups. Each group comprises at least two series of light pulses having different but closely-spaced wavelengths and the same state of polarization (SOP). At least two, and preferably a large number of such groups, are injected and corresponding OTDR traces obtained for each series of light pulses by averaging the impulse-response signals of the several series of light pulses in the group. The process is repeated for a large number of groups having different wavelengths and/or SOPs. The PMD then is obtained from the resulting normalized OTDR... |
| Polarization mode dispersion monitoring and fault correlation | 20080101799 | 20080501 |
| A method and apparatus for a monitoring technique for the rate of change of polarization state and of the polarization mode dispersion is proposed. This technique is used for performance monitoring and fault correlation as well as for the verification of commitments to customers with respect to the transmission system's tolerance to polarization mode dispersion.
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| Systems and methods for polarization mode dispersion mitigation | 20080095487 | 20080424 |
| In one exemplary embodiment, a method comprises transmitting an optical signal via the optical line, measuring a relative change in spectral intensity of the optical signal near a clock frequency (or half of that frequency) while varying a polarization of the optical signal between a first state of polarization and a second state of polarization, and using the relative change in spectral intensity of the optical signal to determine and correct the DGD of the optical line. Another method comprises splitting an optical signal traveling through the optical line into a first and second portions having a first and second principal states of polarization of the optical line, converting the first and second portions into a first and second electrical signals, delaying the second electrical signal... |
| Optical transponders with reduced sensitivity to polarization mode dispersion (pmd) and chromatic dispersion (cd) | 20080095538 | 20080424 |
| Optical transponders with reduced sensitivity to PMD and CD are described. In one embodiment, an optical transponder comprises a differential group delay (DGD) mitigator integrated within the transponder and optically coupled to an optical input port of the optical transponder, an optical receiver integrated within the optical transponder and optically coupled to the DGD mitigator and to an electrical output port of the transponder, and a multi-level transmitter integrated within the optical transponder, where the multi-level transmitter is electrically coupled to an electrical input port and optically coupled to an optical output port of the transponder. In another embodiment, a method comprises receiving and processing an optical input signal using a DGD mitigator integrated within an optical transponder, and receiving an electrical input signal, narrowing the... |
| Testing optically amplified links with time-division multiplexed test signals | 20080085115 | 20080410 |
| A time division multiplexed measurement technique is used for spectral measurements in active wavelength division multiplexed loaded optical links, and offers instantaneous real-time correlation of performance and spectral parameters of the link, which is important for dynamic characterization of link performance during transient effects or polarization mode dispersion fluctuations.
... |
| Differential geomety-based method and apparatus for measuring polarization mode dispersion vectors in optical fibers | 20080079941 | 20080403 |
| A method and apparatus are provided for determining the first and second order polarization mode dispersion (PMD) vectors of an optical device, such as a single mode optical fiber, using only a single input polarization state. This is achieved by passing light beams having a fixed polarization state and frequencies that vary over a range through the optical device that is being tested. The output polarization states of the light beams that have passed through the optical device are measured, and used to form a curve in Stokes space on a Poincare sphere. The shape of this curve is used to approximate the first and second order (and possibly higher order) PMD vectors, using formulas based on differential geometry.
... |
| Compensating method and compensator of first-order polarization mode dispersion, and optical transmission system using same | 20080080805 | 20080403 |
| In a PMD compensator of the present invention, a signal light input to an input terminal is supplied to a polarizer via a polarization controller; a part of polarized light transmitted through the polarizer is branched by an optical coupler as a monitor light; the monitor light is converted into a electrical signal by a photodiode; a clock corresponding to a RZ clock frequency of the signal light is extracted from the electrical signal using a band-pass filter, to thereby monitor the intensity thereof; and the polarization controller is feedback controlled by a PC control section so that the monitored intensity of the clock becomes maximum. As a result, a miniaturized and low-cost PMD compensator which can reliably compensate for first-order polarization mode dispersion of a... |
| Measuring polarization mode dispersion | 20080068607 | 20080320 |
| A device for measuring polarization mode dispersion (PMD) in a device under test (DUT) includes a polarized light source for launching a test beam through the DUT, and a PMD analyzer, which uses one of a plurality of known techniques, e.g. fixed analyzer-Fourier transform (FA-FT) or interferometric, to calculate the PMD from the DUT. A passive depolarizer, made up of a plurality of birefringent elements is disposed between the light source and the PMD analyzer to generate a plurality of carrier frequencies that correspond to the delays imposed by the birefringent elements. The PMD content of the DUT is present around each of the carriers, and the plurality of PMD measurements can be averaged to obtain a more accurate and repeatable measure of the PMD.
... |
| Reducing depolarisation | 20080056729 | 20080306 |
| The present invention provides a method for reducing spreading of a pulse in a transmission line, said spreading being as a result of polarization mode dispersion, comprising inducing predetermined polarization rotations of particle or wave components of the pulse in the transmission line.
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| Method for manufacturing single mode optical fiber having low polarization mode dispersion | 20080041110 | 20080221 |
| and t=(0.21×CladOval)+(0.04×CoreOval)+(0.17×ECC), where y is a maximum spatial frequency of spin [turns/m], Vf is a drawing velocity [mpm], CladOval is a clad ovality [%], CoreOval is a core ovality [%], and ECC is an eccentricity [μm].
... |
| Optical fiber birefringence measurement method and measurement device, and optical fiber polarization mode dispersion measurement method and optical fiber | 20080030720 | 20080207 |
| (where φ represents the phase difference between linear polarization components due to birefringence, Δn represents birefringence, and λ represents wavelength), the birefringence in the infinitesimal interval Δz from the position z to the position z+Δz is obtained.
... |
| Multi-level modulation receiving device | 20080031633 | 20080207 |
| A multi-level modulation receiving device for adaptively compensating for chromatic dispersion and polarization mode dispersion with high precision. Each equalizing filter has at least one variable parameter as a weight therefor and equalizes the waveform of a corresponding channel signal in accordance with an averaged variable parameter value. A signal quality monitor monitors the signal quality of the filter output signal, and a variable parameter value calculator calculates a variable parameter value to be set as the variable parameter, in accordance with the signal quality. A variable parameter averaging unit averages the variable parameter values calculated for respective channels, to generate an averaged variable parameter value, and sends the averaged variable parameter value to the equalizing filters such that the same weight is set in the... |
| Process for producing a low polarization mode dispersion optical fiber | 20080022725 | 20080131 |
| In a process for producing a low polarization mode dispersion optical fiber, which comprises the steps of drawing a glass preform into an optical fiber and of spinning, during drawing, the optical fiber about an optical fiber axis, the spinning is imparted according to a bidirectional and substantially trapezoidal spin function, which includes zones (P) of substantially constant amplitude (plateau) and zones of transition (T) where inversion of the spin direction takes place, wherein the extension (p) of the zones of substantially constant amplitude is greater than the extension (t) of the zones of transition, and the number of inversions of the direction of spin in a length of fiber of 20 m is at most two.
... |
| Method for increasing accuracy of measurement of mean polarization mode dispersion | 20080007719 | 20080110 |
| The present invention provides a method for increasing the accuracy of measurement of mean differential group delay (DGD) from the polarization mode dispersion (PMD) in optical fiber. The method includes a systematic correction to mean-square DGD measured with any conventional mean to minimize systematic error caused by finite source bandwidth. The method further includes a systematic correction to the measurement of mean DGD and mean square DGD from statistics of the second-order PMD (SOPMD) obtained with frequency domain PMD-measuring apparatus. The probability density function (PDF) of either the vector or scalar SOPMD is applied, depending on which quantity is measured. The systematic correction is made to minimize the systematic error in estimating mean DGD, caused by finite source bandwidth, to achieve a two-fold reduction of the... |
| All order polarization mode dispersion compensation with spectral interference based pulse shaping | 20080002972 | 20080103 |
| A method includes determining spectral interference in real time on an optical signal by an optical path, the spectral interference being indicative of polarization mode dispersion by the optical path, and imposing optical pulses with a phase opposite to the spectral interference on the optical signal. Preferably, the imposing step comprises altering the amplitude or phase of a signal indicative of the spectral interference with an active element. The active element is preferably an acousto-optic modulator.
... |
| Integrated polarization beam splitter with quarter-wave plate for polarimeter and pmd compensation applications | 20070296977 | 20071227 |
| An optical device for changing polarization comprises a waveguide having a waveguide end facet coupled to a quarter-wave plate/reflector combination to rotate the polarization of incident light to the waveguide by 90 degrees. In one embodiment, a polarization beam splitter/rotator combination (PBSR) uses a quarter-wave plate in reflection at the end facet of the waveguide. The polarization beam splitter/rotator combination and variations of that structure are applied in various useful topologies as polarization mode dispersion (PMD) compensators and polarimeters.
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| Chromatic dispersion compensating fiber | 20070258686 | 20071108 |
| Disclosed is a chromatic dispersion compensating optical fiber comprising a central core, an intermediate cladding having a width (r2−r1) of 2.0 microns or greater, and a depressed inner cladding having a refractive index difference Dn3 with the external optical cladding of −3.0×10−3 or lower. At a wavelength of 1550 nm, the optical fiber exhibits a positive chromatic dispersion of 21 ps/nm·km or higher and a ratio of mode radius to intermediate cladding radius of (W02/r2) of 0.7 or less. The present optical fiber has a good figure of merit value and limited bending and microbending losses. The optical fiber can be rolled up in a housing of reduced size in a chromatic dispersion compensating optical module having limited insertion losses and reduced polarization mode dispersion
... |
| Polarization scrambler, optical add/drop multiplexer, optical route switching apparatus and wavelength division multiplexing optical transmission system | 20070248361 | 20071025 |
| A polarization scrambler has a polarization state rotating unit rotating the polarization state of a signal light, and a rotation speed controlling unit controlling the rotation speed of the polarization state in the polarization state rotating unit on the basis of the speed and scheme of modulation of the signal light, and the value of polarization mode dispersion of a transmission path on which the signal light is to be transmitted. Degradation of the transmission quality due to PMD is more mitigated than the known techniques.
... |
| Method for characterizing an optical fiber link | 20070201786 | 20070830 |
| A method for characterizing an optical link by its beat length, coupling length and polarization mode dispersion is disclosed. A pulsed signal is sent along said optical fiber link and the backscattered signal (being a POTDR signal) is measured after passing through a polarizer. The length of said optical fiber, the average power difference between two successive minima of said backscattered signal and the number of maxima per unit length are derived. In an iterative way a beat length interval and an interval for the polarization mode coupling parameter are determined until the length of said intervals is below a predetermined value, yielding a value for the beat length and the coupling length, and the polarization mode dispersion is calculated.
... |
| Methods and systems for controlling fiber polarization mode dispersion (pmd) | 20070201810 | 20070830 |
| A method is provided for predicting an installed performance parameter of an optical fiber cable. The method includes obtaining a measurement indicative of a value of the performance parameter at a first moment in time. A measurement indicative of a value of the performance parameter at a second moment in time may then be obtained. A first correlation may then be determined between the measurement at the first moment in time and the measurement at the second moment in time. A value of the performance parameter at the second moment in time may then be estimated based upon the measurement at the first moment in time in combination with the first correlation, the first correlation being based upon observations of a manner in which the performance... |
| Method and apparatus for the evaluation of polarization mode dispersion in optical fibers | 20070189656 | 20070816 |
| A method of evaluating the Polarization Mode Dispersion (PMD) of an optical fiber by arranging the optical fiber at substantially zero tension on a surface, propagating prescribed evaluation optical signals along the optical fiber, measuring fiber Differential Group Delay (DGD) values in response to the evaluation optical signals, repeating at least once the acts of propagating and measuring, each time preliminarily inducing a change in a mode coupling of the fiber, and determining the fiber PMD on the basis of a calculated DGD average value. Changes in the polarization mode coupling of the fiber are induced by, moving at least a section of the fiber substantially orthogonally to the surface. An improved PMD evaluation apparatus includes a fiber arrangement surface adapted to have a fiber under... |
| Method for optical transmission of a polarization division multiplexed signal | 20070166046 | 20070719 |
| The polarsation-multiplexed signal contains two data signals that are orthogonally polarised in relation to one another. Their carrier signals are derived from the same source and thus have the same wavelength. The phase difference between the carrier signals, is adjusted or regulated in such a way that it corresponds to 90°. The phase difference of the carrier signals permits the susceptibility to polarization mode dispersion to be significantly reduced.
... |
| System and method for measurement of optical parameters and characterization of multiport optical devices | 20070146721 | 20070628 |
| System and method for measurement of optical parameters and characterization of multiport optical devices constituted by process control systems, one or more sources of optical test signal (11) (tunable laser source), optical circuit including optical fiber and several other optical components arranged so as to constitute an interferometric optical arrangement, optical connectors, optoeletronic interfaces, photodetectors, analogical electronic; circuits, digital electronic circuits for digital signal processing and electronic circuits for data acquisition, the test and reference optical signals traversing paths with any lengths, that can be identical or distinct, the optical signal traversing at least one of said paths of interferometer being phase- and/or frequency-modulated. The signals of both interferometer arms are summed at a same photodetector (26) that translates to the electric domain the heterodyning of... |
| Effective control algorithm for optical polarization mode dispersion compensators | 20070133997 | 20070614 |
| The present invention includes apparatus and method of a variable step size dithering control algorithm for polarization mode dispersion controllers (PMDCs). The dithering step size of the PCs is adjusted according to the feedback signal including degree of polarization (DOP).
... |
| Otdm transmission method and apparatus | 20070109957 | 20070517 |
| An OTDM transmitting method and transmitter realizing an OTDM distortion-free transmission substantially not relying upon dispersion. A time division multiplexed OTDM signal from an OTDM signal transmitter (1) enters an optical Fourier transform unit (2). Optical Fourier transform can be carried out most accurately so long as the optical pulse is a chirp-free Fourier transform limit pulse. The optical Fourier transform unit (2) converts the time waveform of the pulse into a signal on the frequency axis, and an optical inverse Fourier transform unit (2′) converts a spectral shape on the frequency axis into a time waveform (pulse). An optical fiber transmission line (3) is a transmission line having an arbitrary dispersion and a polarization mode dispersion. These dispersions may involve a time variation. An OTDM... |
| Polarization mode dispersion compensator and polarization mode dispersion compensating method | 20070110451 | 20070517 |
| An amount of change of a control signal applied to a polarization controller in a polarization mode dispersion compensator is determined for each feedback loop by evaluating degree of polarization response in past feedback loops.
... |
| Method and apparatus for detecting localized polarization dependent anomalies on optical transmission lines | 20070086783 | 20070419 |
| The position and amount of localized polarization dependent anomalies such as polarization mode dispersion and/or polarization dependent loss may be measured by applying a polarization modulated probe signal to an optical transmission line. The polarization modulated probe signal is returned via optical feedback paths positioned along the line, and is detected by a probe signal receiver to identify the position and strength of the anomaly.
... |
| Optical fiber having reduced polarization mode dispersion (pmd) and method for producing the same | 20070062223 | 20070322 |
| A process for producing optical fiber preform having symmetrically and completely collapsed capillary which is suitable for producing optical fiber having reduced PMD is provided, wherein collapsing of the capillary in the hollow soot porous body or sintered glass body is carried out under variable vacuum. An optical fiber preform produced by such method and optical fiber produced from such optical fiber preform are also provided.
... |
| Signal waveform deterioration compensator | 20070065162 | 20070322 |
| The waveform deterioration detection range is broadened and multi bit rates can be handled. A chromatic dispersion compensator (or polarization mode dispersion compensator) (102) receives a waveform-deteriorated NRZ optical signal entered through an input fiber (101) and compensates it. On the other hand, an optical detector (106) receives part of output light and a sampling circuit (A/D converter) (107) performs asynchronous sampling of received waveform intensity. A control circuit (110) calculates the nth even moment (n is 4 or more) from an obtained waveform amplitude histogram and performs control to minimize its value.
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| Method of evaluating fiber pmd using potdr trace | 20070046928 | 20070301 |
| A method for screening fiber polarization mode dispersion using a polarization optical time domain reflectometer is disclosed. A pulse radiation is emitted into an end of the fiber under test, and the backscattered radiation is measured by the POTDR and used to obtain an OTDR trace. A pulse radiation is emitted into an opposite end of the fiber under test, and the backscattered radiation is measured by the POTDR and used to obtain another OTDR trace. Either one or both traces are analyzed to compare the variation of intensity of signals along the length of the fiber, the variation in signals relating to the PMD along the length of the fiber.
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| Plasmon-photon coupled optical devices | 20070008602 | 20070111 |
| The present invention is directed to optical devices. More specifically, the disclosed devices include a film defining a periodic array of surface elements so as to give rise to surface plasmon polaritons. The film also includes at least a single aperture having a diameter less than the wavelength of light. In one embodiment, the surface elements can be an array of anisotropic apertures and the films can act as a polarizer. The disclosed devices can also include a material having a variable refractive index substantially adjacent to the metal film. For example, the refractive index of the adjacent material can vary according to some characteristic of the light incident to the device, for instance, the intensity or the angle of incidence of the light. In this... |
| Method of evaluating fiber pmd using composite potdr trace | 20070002310 | 20070104 |
| A method for screening fiber polarization mode dispersion using a polarization optical time domain reflectometer. A pulse radiation is emitted into the fiber under test, and the backscattered radiation is measured by the POTDR and used to obtain a POTDR trace. A composite trace of more than one POTDR trace is obtained. The composite trace is then analyzed to compare the variation of signals along the length of the fiber, the variation in signals relating to the level of PMD along the length of the fiber. Because high levels of PMD correspond to localized levels of low variability, by setting the variability of signal threshold sufficiently low, fibers having unacceptably high localized PMD can be identified and removed.
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| Polarized lightwave reflectometry method (potdr) | 20060285105 | 20061221 |
| A polarized lightwave reflectometry method including the steps of sending at least two polarized light signals into the optical fiber to be tested, the signals presenting a determined angular offset relative to each other so that the polarization mode dispersion coefficient remains independent of any rotation of polarization in the optical fiber under test; extracting a scalar parameter of the relative noise type for each trace obtained by back-scattering of the light signal; and estimating the polarization mode dispersion coefficient by a function having a single scalar input, which function is of the type based on exponentials and has the form exp (a+bP+cP−1).
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| Optical communication line and system with reduced polarization mode dispersion | 20060268392 | 20061130 |
| An optical communication line for transmitting an optical signal having a predetermined wavelength has a plurality of spans and at least one PMD compensation device adapted to process the optical signal so as to obtain in output a polarized optical signal having associated a maximum power fraction of the optical signal. The PMD compensation device is inserted between two spans of the line.
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| Apparatus for mitigating the effects of polarization mode dispersion of a plurality of optical signals | 20060263094 | 20061123 |
| A PMD mitigation apparatus for mitigating the effects of PMD of a plurality of input optical signals, has a processing unit having a first input for the plurality of input optical signals, a second input and an output; a feedback control unit having an input coupled to the output of the processing unit and an output coupled to the second input of the processing unit. Under the control of a control signal, the processing unit is adapted to act on the polarization of the plurality of input optical signals separately so as to obtain at its output an aggregate having a corresponding plurality of polarized optical signals having associated a maximum fraction of power of the plurality of input optical signals. The feedback control unit is... |
| Polarization mode dispersion compensator and method thereof | 20060245680 | 20061102 |
| A polarization transformer in a polarization mode dispersion compensator is adjusted over its changing device characteristics with environmental changes and time by using a feedback signal indicating a state of polarization and a distortion of an output optical signal of compensating optics.
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| Method and system for the controlled production of polarization mode dispersion | 20060245706 | 20061102 |
| A method and a system to produce, either in numerical simulations or in experiments, specified amounts of first, second and higher order PMD in a controlled manner, in particular large amounts. Parameters can be adjusted to obtain specific ranges of first, second and higher order PMD, and importance sampling can be used to determine the probability that the resulting PMD events can be obtained in realistic situations. Individual results obtained using specific parameter values can be combined to produce even larger ranges of PMD.
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| Method for producing an optical fiber having low polarization mode dispersion | 20060230791 | 20061019 |
| A method for producing an optical fiber having low polarization mode dispersion, by the steps of a) providing an optical fiber perform of glass material; b) heating the glass material of an end portion of the optical fiber perform; c) drawing the heated glass material at a drawing speed V to form an optical fiber, the drawn glass material having a viscous zone; and d) applying to the optical fiber a substantially sinusoidal spin, which is transmitted to the viscous zone, the spin function frequency ν , the viscous zone length L and the drawing speed V being such that both a torsion and at least a 50% detorsion are applied to the viscous zone.
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| Method for manufacturing an optical fiber preform by mcvd | 20060230793 | 20061019 |
| Disclosed is a method for manufacturing an optical fiber preform in MCVD, which simultaneously performs an etching process for injecting a reaction gas for etching into a tube and a collapsing process for heating and collapsing the tube in order to minimize or eliminate an index dip existing at the center of the preform core. By using this method, the index dip phenomenon of the optical fiber preform can be minimized or eliminated, so it is possible to make an optical fiber having improved optical characteristics, particularly having improvement in a bandwidth and a polarization mode dispersion (PMD).
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| Mitigating the effect of pulse distortions along an optical fiber communications link | 20060222293 | 20061005 |
| A method of mitigating the effect of deterministic (only slowly changing) pulse distortions along an optical fiber communications link transmitting a train of pulses, and apparatus for performing it. Plural copies of the pulse train are made and are all coherently added together with the original train after delaying each copy by a different amount. The amplitude and phase of each copy are independently adjusted, normally by a computer, to optimize the resulting pulse shape. The technique is capable of mitigating (not totally eliminating) distortions of diverse origin, including but not limited to polarization mode dispersion, chromatic dispersion, multiple reflections, and self-phase modulation, even if they interact with each other.
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| Optical isolator, attenuator, circulator and switch | 20060203340 | 20060914 |
| A polarization independent optical isolator, attenuator, circulator and switch include at least a combination of birefringent prisms with parallel optic axes for dividing an input beam into parallel polarized beams or for combining parallels polarized beams into an output beam. In particular, an optical isolator (8) includes a first combination of birefingent prisms (10, 11), Farady rotator (12), half waveplate (13) and a second combination of birefringent prisms (14, 15). Devices may be conservative in the use of birefringent material, high in isolation and free from polarization mode dispersion.
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| Optical fiber, method for manufacturing same and optical transmission channel | 20060198591 | 20060907 |
| The present invention provides an optical fiber of which a zero dispersion wavelength falls within a range of between 1,250 nm and 1,350 nm inclusive, transmission loss at 1,550 nm is equal to or less than 0.185 dB/km, chromatic dispersion at 1,550 nm is within the range of 19±1 ps/nm·km, a dispersion slope at 1,550 nm is equal to or less than 0.06 ps/nm2·km, an effective area Aeff is equal to or more than 105 μm2, a cable cutoff wavelength λcc is equal to or less than 1,530 nm, polarization mode dispersion is equal to or less than 0.1 ps/km1/2, and a loss when the optical fiber is wound on a mandrel having an outer diameter of 20 mm is equal to or less than 10... |
| Optical fiber and method of measuring polarization mode dispersion of optical fiber | 20060192942 | 20060831 |
| A method of measuring polarization mode dispersion (PMD) of an optical fiber, includes estimating PMD when an optical fiber is formed as an optical cable, from a beat length when the optical fiber is wound around a bobbin, and an average coupling length when the optical fiber is formed as the optical cable.
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| Method and apparatus for measuring polarization mode dispersion | 20060164652 | 20060727 |
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| Compensation of polarization mode dispersion in single mode fiber for maximum-likelihood sequence estimation | 20060153576 | 20060713 |
| An output signal of a single mode fiber (SMF) is spectrally shaped to achieve characteristics of a predefined channel “target” response. The target response is that of a partial-response, maximum-likelihood channel with additive white Gaussian noise. A receiver employs a maximum-likelihood sequence estimation (MLSE) detector having its detection algorithm, such as a Viterbi algorithm (VA), matched to the target response. Thus, state, branch, and path metric calculations for a Viterbi trellis may be optimized for a channel having this target response.
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| Optical fiber having a low polarization mode dispersion and process and apparatus for producing it | 20060147166 | 20060706 |
| An apparatus for producing a low-PMD optical fiber having a furnace for melting a lower portion of an optical preform; a traction device for pulling an optical fiber from the lower portion of an optical preform; a spinning device for imparting a substantially constant and unidirectional spin to the optical fiber as it is pulled, which causes the fiber to undergo an elastic torsion; a winding device for winding the optical fiber onto a reel; and a twisting device for imparting to the spun optical fiber a unidirectional twist in a direction opposite the elastic torsion, so as to control the residual twist in the optical fiber. A process for producing the fiber, an optical fiber and a cable are also provided.
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| Method and apparatus for dynamic polarization control | 20060126989 | 20060615 |
| A dynamic polarization controller (“DPC”) that and method of dynamic polarization control useful in optical networks is disclosed. The DPC of the present invention has a polymeric optical waveguide formed on a substrate, such as a silicon wafer. An intermediate portion of the waveguide is suspended over a cavity, and a deflecting structure, such as an electrodes, is provided for controllably exerting a force on the suspended portion of the waveguide. Exerting a deflecting force on the suspended portion of the waveguide induces controllable birefringence in the waveguide core and, thereby allows dynamic control over the polarization properties of light passing through the DPC. An array of DPC's of the present invention can be formed on a single substrate and used in an optical network, for... |
| Polarization mode dispersion compensator, polarization mode dispersion compensating method, and its application to optical communication system | 20060110092 | 20060525 |
| The present invention provides a polarization mode dispersion compensator comprising: a compensating portion which includes a first polarization controller which performs polarization conversion on light propagating along an optical transmission line and a DGD (Differential Group Delay) emulator which adds a DGD to the light which is polarization-converted by said first polarization controller, said compensating portion being for compensating polarization mode dispersion which occurs in the light while the light propagates along the optical transmission line; a second polarization controller for performing polarization conversion on the light, of which the polarization mode dispersion is compensated, so that a state of polarization of the light can be one linear polarization; a polarization beam splitting portion for splitting the light, which is polarization-converted by said second polarization controller,... |
