Class / Patent application number | Description | Number of patent applications / Date published |
398152000 | Including polarization | 66 |
20080232816 | Polarization-multiplexing optical transmitter polarization-multiplexing optical receiver, polarization-multiplexing optical transceiving system, and controlling method thereof - By using low-frequency signals, an optical transmitting unit modulates one of a wavelength, a transmission timing, and an intensity of light as a carrier wave. A polarization multiplexer synthesizes the output light signals, modulated by the optical transmitting unit, in polarization states orthogonal to each other and generates polarization-multiplexing signals. A polarization splitter splits by extracting two orthogonal polarization components from the polarization-multiplexing signals. The polarization states of the polarization-multiplexing signals are controlled by a polarization controller in an optical receiving unit. A band-pass filter extracts components transmitting through passbands from output signals of the optical receiving unit and outputs an intensity of the components. Based on the intensity output from the filter, a controlling circuit generates feedback control signals for maximizing a ratio of the components of the low-frequency signals and by using the feedback control signals, the polarization controller controls the polarization states of the optical multiplexing signals. | 09-25-2008 |
20080260393 | Transceiver and Method for High-Speed Auto-Compensating Quantum Cryptography - Provided are an auto-compensating quantum cryptography transceiver and method of transmitting a quantum cryptography key at a high speed. A quantum cryptography transmitter includes a wavelength converter, an optical attenuator, an optical phase modulator, and a Faraday mirror. A quantum cryptography receiver includes a polarization beam splitter, an optical coupler, an optical filter, and a photon detector. Thus, a limit of a transmission rate caused by Rayleigh scattering of an optical fiber can be overcome. | 10-23-2008 |
20080279564 | Systems and Methods of Polarization Time Coding for Optical Communications - Systems and methods of polarization-time coding are disclosed. One method includes encoding information in orthogonal polarizations of light and correlated information in multiple time slots, and transmitting the information using the orthogonal polarizations in the time slots. Another method includes receiving a first input pair which specifies a first polarization state and a second input pair containing which specifies a second polarization state; transforming each input pair according to a matrix specifying a conjugate operation to produce four output pairs. The method further includes transmitting at a first time the first output pair using the first polarization state and the third output pair using the second polarization state. The method further includes transmitting at a second time the second output pair using the first polarization state and the fourth output pair using the second polarization state. | 11-13-2008 |
20080292321 | Optical Transmitter, Optical Network and Method for Compensation of Polarization Mode Dispersion - 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. | 11-27-2008 |
20080310856 | Method and Device for Readjusting a Polarization Drift - For readjusting a polarization drift in the transmission of a polarization-encoded optical signal from a transmitter via a light guide to a receiver, optical auxiliary signals having the same wavelength as the polarization-encoded signal as well as different polarizations as in correspondence with a first base and a second base are fed into the light guide on the side of the transmitter while the transmission of the polarization-encoded signal is interrupted, and the optical auxiliary signals are picked up from the light guide and checked for shifts of the different polarizations by a polariometer on the side of the receiver, whereupon, in the event of the detection of polarization shifts, the different polarizations shifted during the transmission are displaced in the sense of the polarization set values via a polarization controller associated with the light guide. | 12-18-2008 |
20090022498 | OPTICAL TRANSMISSION SYSTEM - In the transmitting apparatus, phase modulation means phase-modulates a signal light from a signal source based on data. Polarization modulation means polarization-modulates the signal light which is phase-modulated by the phase modulation means so that the polarization directions of temporally adjacent unit data are orthogonal to each other. In the receiving apparatus, interference means causes the signal light transmitted from the transmitting apparatus to interfere with a signal light such that the signal light is delayed by an even number of unit data. Intensity detecting means detects the intensity of the signal light obtained by interference by the interference means to detect data. | 01-22-2009 |
20090060524 | High frequency signal optical transmission system and high frequency signal optical transmission method - A filter conducts the round trip by using the return optical signal that has been shifted in frequency, and measures the transmission optical signal and the return signal in phase by the principle of the Michelson interferometer at the same time, independently, and splits the two optical signals. A polarization state in which transmission and reception optical signals within an optical phase shifter which enters one route of the two optical signals are made orthogonal to each other is provided, to thereby distinguish the transmission and reception signals of the round trip from each other. The light is allowed to pass the shifter in incoming and returning to remove the polarization rotation of the shifter by using the reversibility of the light. Then, the phases of the transmission signal and the return signal are measured and synchronized with each other to conduct the transmission phase compensation. | 03-05-2009 |
20090087191 | COLOR SENSORS USING POLARIMETRIC TECHNIQUES - Embodiments include n apparatus including a color sensor including a transmitter portion and a receiver portion, the transmitter portion including a light source operable to generate and transmit a light having a particular range of wavelengths, the receiver portion including a first detector operable to receive a first portion of the light emitted from the transmitter portion and to measure a luminance of the received first portion of the emitted light, and a second detector including a polarization filter, the second detector operable to receive a second portion of the light emitted from the transmitter after the second portion has passed through the polarization filter, and operable to measure a pure color of the received second portion of transmitted light. | 04-02-2009 |
20090087192 | NEAR INFRARED SENSOR SYSTEM WITH NANO-IMPRINTED WIRE-GRID POLARIZERS AND METHOD - Example embodiments of a near-Infrared (NIR) sensor system and methods for detecting changes in polarization are generally described herein. Other example embodiments may be described and claimed. In some example embodiments, the sensor system includes a transmit optical element to transmit optical signals with a polarization, and a receive optical element to receive optical signals with an orthogonal polarization. The transmit and receive optical elements may include nano-imprinted wire-grid polarizers configured to polarize at least infrared IR wavelengths. In some example embodiments, birefringent filter layers may be used to induce an additional polarization state on the transmitted and received optical signals. | 04-02-2009 |
20090087193 | Polarization mode dispersion compensation - 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. | 04-02-2009 |
20090142071 | METHOD AND SYSTEM FOR POLARIZATION MODE DISPERSION COMPENSATION - The invention relates to a method and a system for controlling a PMD compensator ( | 06-04-2009 |
20090148170 | Skew Compensation Across Polarized Optical Channels - Embodiments of the present invention provide systems, devices and methods for managing skew within a polarized multi-channel optical transport system. In a DP-QPSK system, skew between polarized channels is compensated within the transport system by adding latency to at least one of the polarized channels. The amount of added latency may depend on various factors including the skew tolerance of the transport system and the amount of skew across the channels without compensation. This latency may be added optically or electrically, and at various locations on a channel signal path within a transport node, such as a terminal transmitter or receiver. Additionally, various embodiments of the invention provide for novel methods of inserting frame alignment bit sequences within the transport frame overhead so that alignment and skew compensation may be more efficiently and accurately performed at the transport receiver. | 06-11-2009 |
20090238579 | Polarization Demultiplexing Optical Receiver Using Polarization Oversampling and Electronic Polarization Tracking - An optical receiver utilizes differential quadrature phase-shift keying (DQPSK) demodulation and electrical crosstalk rejection to relax requirements on filter misalignment with a carrier signal and to enable electronic polarization demultiplexing of optical signals. The optical receiver uses additional polarization state information when performing differential phase measurements on the optical signals. This provides information that ensures that data can be recovered by the optical receiver regardless of the state of polarization introduced during transmission of the optical signals. The optical receiver over samples the optical signals, which enables electrical polarization demultiplexing of the optical signals. The electrical crosstalk rejection provides a tracking algorithm that isolates received optical signals, and reduces crosstalk between data sequences. | 09-24-2009 |
20090274469 | Polarization multiplexed optical transmitting and receiving apparatus - In a polarization multiplexed optical transmitting and receiving apparatus, output light from a light source section of a transmission unit is separated in a polarization separating section, and then modulated in first and second modulation sections, and the modulated lights are synthesized in a polarization synthesizing section, and transmitted to an optical transmission line. Then the polarization multiplexed light propagated through the optical transmission line is demodulated in a reception section of a reception unit, and together with this, transmission characteristic information of the reception light is transferred to the transmission unit. The transmission unit that receives the transmission characteristics information controls a delay section that adjusts a delay amount of relative phases of drive signals of the modulation sections, so that the transmission characteristics of the polarization multiplexed light are within an allowable range. As a result, pulse timing between orthogonal polarization components of the polarization multiplexed light can be flexibly changed with a simple configuration. | 11-05-2009 |
20090279900 | SYSTEMS AND METHODS FOR THE MITIGATION OF POLARIZATION MODE DISPERSION IMPAIRMENTS IN FIBER OPTIC LINKS - 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 small fraction of the FEC error correction capability. | 11-12-2009 |
20090285583 | SNR ENHANCEMENT IN MODULATING RETROREFLECTOR OPTICAL COMMUNICATION LINKS - An optical communication system may include a light transmission unit transmitting a light beam having a first polarization, a quarter waveplate to receive the light beam and to modify the light beam to have a second polarization, and a retroreflector to receive the light beam from the quarter waveplate and reflect the light beam to the quarter waveplate, which modifies the light beam to have a third polarization. The optical communication system may also include a half waveplate to modify the first polarization such that the first polarization is about 90 degrees rotated compared to the third polarization, and a polarizer to pass the light beam having the third polarization and to block most of the light beam having the first polarization. | 11-19-2009 |
20090290882 | OPTICAL SIGNAL PROCESSING DEVICE - Signal light, pumping light and control light having different wavelengths are input to a nonlinear optical medium. The power of the pumping light is controlled to generate a desired gain in the nonlinear optical medium. The power of the control light is controlled to saturate the gain of the nonlinear optical medium. | 11-26-2009 |
20090304392 | REFLECTIVE OPTICAL CIRCULATOR - Provided is a reflective optical circulator capable of improving characteristics by preventing the occurrence of PDL and non-uniformity of insertion losses of reciprocating optical paths. The reflective optical circulator includes: an optical element unit having a first polarization separating element, a 45° non-reciprocal polarization plane rotating element, a phase element for rotating a polarization plane of an incident light by 90°, and a second polarization separating element; a light incidence/emission unit; a lens; and a reflector. All waveguides are disposed at an equivalent distance from a central point, and a shift amount of an extraordinary ray in the second polarization separating element is set to be larger than a shift amount of an extraordinary ray in the first polarization separating element. In addition, the phase element is constructed with two phase optical elements, and only one polarization component is allowed to transmit through the two phase optical elements. In addition, a size of the second polarization separating element is set so that light transmits through only one path of reciprocating optical paths, and the two polarization components are reflected by the reflector with a point symmetry, and a light in the forward direction is set to be incident to the second polarization separating element before being reflected. | 12-10-2009 |
20100003034 | SYSTEMS AND METHODS FOR ADAPTIVE POLARIZATION TRANSMISSION - The present invention describes methods and apparatus for adaptive polarization transmission. An exemplary embodiment of the present invention provides an adaptive polarization transmission method. The method includes the step of analyzing at a transmitter device a first set of polarization state information relating to a first wireless signal path. Furthermore, the method includes the step of adapting a transmission signal to be distributed by the transmitter device based on at least the first set of polarization state information. In addition to adaptive polarization transmission methods, the present invention provides various adaptive polarization transmission systems. In an exemplary embodiment, an adaptive polarization transmission system includes a transmitter device. The transmitter device includes an analyzing unit for processing a first set of polarization state information relating to a first wireless signal path. Furthermore, the transmitter device includes an adapting unit for adapting a transmission signal to be distributed by the transmitter device based on at least the first set polarization state information. | 01-07-2010 |
20100021178 | Polarization direction synchronization detecting circuit and receiving apparatus - A switch is to be inputted a modulation signal including the synchronization signal extracted from a received communication signal as a control signal, is to be inputted a detection signal detected by a photodetector that receives a polarization modulation signal adjusted to a polarization direction of a quantum cipher signal, and selectively switches and outputs one of the detection signal and an inverted signal of the detection signal according to the control signal. A low-pass filter outputs the output signal of the switch, whereby a plus level signal is outputted when a relative angle difference Δθ between polarization axes on a transmission side and a reception side is larger than a predetermined polarization angle, a 0 level signal is outputted when Δθ is equal to the predetermined polarization angle, and a minus level signal is outputted when Δθ is in a range of the predetermined polarization angle from 0 degree. | 01-28-2010 |
20100034541 | PMDC FEEDBACK SIGNAL FOR ALTERNATE POLARIZATION DPSK SYSTEM - A feedback signal indicative of the average RF power of an APol-DPSK optical signal is used by a PMD compensator to adjust the amount of compensation applied to the optical signal. | 02-11-2010 |
20100054753 | APPARATUS AND METHOD FOR STABILIZING POLARIZATION STATE - An apparatus includes: a polarizing beam splitter for splitting the input light into a first light and a second light and for outputting the first light and the second light into optical paths, respectively; a polarization rotator rotating polarized light of the light path by approximately 90 degree; a first path length adjuster adjusting a difference path length between the optical paths in order to be approximately equal to zero; a second path length adjuster adjusting a difference path length between the optical paths in order to be an integer multiple of a wavelength of the input light; an optical attenuator arranged adjusting a propagation loss of the optical path in order to approximately match the propagation losses of the optical paths; and an output element for combining the first light and the second light from the paths and for outputting the output light. | 03-04-2010 |
20100080569 | METHOD AND APPARATUS FOR GENERATING DQPSK ENCODING OPTICAL SIGNAL - A method and an apparatus for generating a differential quadrature phase shift keying (DQPSK) code optical signal are provided. The method may includes splitting an optical signal to obtain two polarized optical signals, modulating and phase-shifting one of the two polarized optical signals to obtain a phase-shifted and polarized optical signal, and modulating the other of the two polarized optical signals to obtain another polarized and modulated optical signal. The phase-shifted and polarized optical signal may be combined with the other polarized and modulated optical signal to obtain a polarization multiplexed optical signal. The method may further include, polarizing the polarization multiplexed optical signal to obtain the DQPSK code optical signal. The apparatus may include a polarization beam splitter (PBS), modulators, a phase-shift controller, a polarization beam combiner (PBC), and a polarizer. Through the processes of beam splitting, modulation, phase-shifting, beam combination, and polarization, the DQPSK code optical signal can be generated stably. | 04-01-2010 |
20100111541 | Generation of Quantum-Correlated and/or Polarization Entangled Photon Pairs with Unequal Wavelengths - The invention provides an apparatus and method for generating quantum-correlated and/or polarization-entangled photon pairs with unequal wavelengths. The photon pairs generated collinearly with respect to the pump light via a nonlinear process in a nonlinear optical medium are collected into a single mode fiber and split using a dichroic device. The wavelengths of photons constituting a pair are selected such that, first, their efficient propagation in the same single mode optical fibre, and second, their efficient splitting with high switching ratio, is possible. A detected rate ˜10 | 05-06-2010 |
20100142970 | Direct Detection Differential Polarization-Phase-Shift Keying for High Spectral Efficiency Optical Communication - Efficient apparatus, methods, systems and devices to generate, transmit and detect optical differential polarization-phase-shift keying signals are disclosed for high spectral efficiency optical communication systems. It includes an electrical encoder and an optical encoder for generation of differentially encoded polarization-phase modulated optical signals and optical demodulators and balanced detectors for detection of the optical signals. The optical signals are transmitted through optical fiber links or free space. The electrical encoder maps independent data channels into differentially-encoded data sequences. In the optical encoder, the encoded data sequences from the electrical encoder drive optical modulators to generate differentially-encoded polarization-phase modulated optical signals at a symbol rate equal to the bit rate of each input data channel. After transmission through a transmission medium, the optical signals are demodulated optically and the original data are recovered by multilevel detection, without recovering the polarization state of received signals. | 06-10-2010 |
20100189445 | OPTICAL COMMUNICATION SYSTEM AND OPTICAL RECEIVER - An optical receiver for receiving an optical signal that transmits a first data signal and a second data signal, including: an optical front-end configured to generate a digital signal that represents the optical signal; a detector configured to detect a state of the optical signal by using the digital signal and output state information that represents the state of the optical signal; a state controller configured to control the digital signal on the basis of the state information in order to recover the first data signal; and a data recovery configured to recover the second data signal on the basis of the state information. | 07-29-2010 |
20100196016 | Polarization Multiplexing with Different DPSK Modulation Schemes and System Incorporating the Same - Polarization multiplexing with different differential phase shift keying (DPSK) schemes generally uses DPSK modulated signals modulated using different DPSK modulation schemes and combined with orthogonal polarizations relative to each other. The different DPSK modulation schemes may use different DPSK phase shifts to represent data, such as a regular DPSK modulation scheme and a π/2 DPSK modulation scheme. By using different DPSK modulation schemes to represent data on the orthogonally polarized signals, the DPSK demodulators may effectively separate the orthogonally polarized signals using the property of the DPSK receivers. To optimize performance, the DPSK modulated signals may also be bit-interleaved when combined with orthogonal polarization. | 08-05-2010 |
20100221018 | Polarization mode dispersion suppressing method and polarization mode dispersion suppressing apparatus - 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 on the optical carrier intensity signal such that the optical carrier wavelength component intensity becomes minimal. | 09-02-2010 |
20100232804 | METHODS AND SYSTEMS FOR POLARIZATION MULTIPLEXED MULTILEVEL MODULATION FOR OPTICAL COMMUNICATION - Multilevel soft-equalizer detectors, such as a maximum a posteriori probability (MAP) detector, suitable for use in polarization multiplexed optical communications using multilevel modulations and coherent detection are disclosed. Detection systems and methods may consider two symbols transmitted over two orthogonal polarization states as a two-component symbol, which is effective in eliminating the bit error ratio (BER) floor phenomenon introduced by conventional soft equalizers. | 09-16-2010 |
20100247109 | PMDC FEEDBACK ARRANGEMENT FOR APOL-DPSK - 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 Tb09-30-2010 | |
20100260504 | OPTICAL TRANSMISSION SYSTEM - An optical transmission system includes an optical transmitter that includes first and second light sources, first and second phase modulators respectively modulating light from the first and the second light sources, and a polarized beam combiner combining the light output from the first and the second phase modulators to output an optical signal; and an optical receiver that includes a local oscillator, a polarization beam splitter splitting, according to polarization, the optical signal transmitted from the optical transmitter, and first and second digital coherent receivers corresponding to the first and the second phase modulators, and including a frontend that mixes light from the local oscillator and the polarization-split optical signal to output an electrical signal of real and imaginary parts, an analog-digital converting unit converting the electrical signal to a digital signal, and a digital signal processing unit estimating phase of the digital signal and extracting a signal. | 10-14-2010 |
20110142455 | CROSSTALK COEFFICIENT ESTIMATING APPARATUS AND CROSSTALK COEFFICIENT ESTIMATING METHOD - This invention relates to crosstalk coefficient estimating apparatus and crosstalk coefficient estimating method. The crosstalk coefficient estimating apparatus is used to estimate a crosstalk coefficient of crosstalk inflicted on one channel of an optical fiber transmission system comprising two or more channels. The crosstalk coefficient estimating apparatus comprises a complex conjugate unit, for obtaining a complex conjugate signal for signal in one polarization-state of another channel other than said one channel; a multiplying unit, for multiplying the complex conjugate signal obtained by the complex conjugate unit with signal in another polarization-state of the another channel; and a filter, for filtering the multiplication result of the multiplying unit to obtain a crosstalk coefficient of crosstalk inflicted on the signal in one polarization-state of said one channel, wherein a transmission function of the filter is set according to system parameters of the optical fiber transmission system. | 06-16-2011 |
20110142456 | APPARATUS AND METHOD FOR DETECTING SIGNAL BEAM - A signal-light detection apparatus includes a polarization extractor that extracts a polarization component that is substantially in parallel with a specified axial direction from an input light, a polarization rotator that changes a relative angle between a direction of polarization of the input light and an axial direction of the polarization extractor, a photodetector that detects an optical power of the polarization component extracted by the polarization extractor, and a determination device that determines whether the input light includes a signal component, based on a variation in the optical power detected by the photodetector. | 06-16-2011 |
20110150498 | OPTICAL COMMUNICATIONS WITH POLARIZATION DEPENDENT LOSS COMPENSATION - The invention related to the system and method for optical communication using light of two polarization states. Polarization distortion loss (PDL) is compensated by implementation of polarization controllers at both the transmitter and receiver sides. The transmitter controller performs a mixing transformation of beam with two polarizations, while the receiver controller performs the same transformation in the opposite direction with exactly same sequence as in the transmitter part. A cross scrambling and a polarization rotation represented by matrix multiplication are examples of such mixing polarization transformations. The averaged PDL induced errors are corrected by the FEC code plus interleavers. | 06-23-2011 |
20110182589 | Optical Transmission and Reception System, and Optical Receiver - An optical signal of an optical transmission part is brought into a high-speed polarization scrambling state by a polarization scrambling part, and transmitted to en optical fiber transmission line as the optical signal from the optical transmitter. The optical signal passing through the optical fiber transmission line is inputted to an optical receiver. The optical signal inputted to the optical receiver is converted into an electric signal by a polarization dependent photoelectric detection part. The converted electric signal is inputted to a digital signal processing part having a polarization scrambling cancel part of canceling the polarization scrambling state by a digital signal processing operation. At the digital signal processing part, the polarization scrambling state of the electric signal is canceled, and a data signal is outputted. | 07-28-2011 |
20110243573 | SIGNAL EQUALIZER IN A COHERENT RECEIVER - A signal equalizer for compensating impairments of an optical signal received through a link of a high speed optical communications network. At least one set of compensation vectors are computed for compensating at least two distinct types of impairments. A frequency domain processor is coupled to receive respective raw multi-bit in-phase (I) and quadrature (Q) sample streams of each received polarization of the optical signal. The frequency domain processor operates to digitally process the multi-bit sample streams, using the compensation vectors, to generate multi-bit estimates of symbols modulated onto each transmitted polarization of the optical signal. The frequency domain processor exhibits respective different responses to each one of the at least two distinct types of impairments. | 10-06-2011 |
20110268456 | OPTICAL TRANSMISSION SYSTEM, TRANSMITTER, RECEIVER AND METHOD - In the optical transmitting system, the optical transmitter transmits a polarization combined signal light obtained by combining a pair of lights having different polarization orientation, and the optical receiver separates the combined signal light. In the optical transmitter, a polarization changer changes a state of polarization of the polarization combined signal light. In the optical receiver, a polarization reverse-changer changes the state of the polarization combined signal light in a reverse direction of the change that polarization changer applies. | 11-03-2011 |
20110305461 | APPARATUS AND A METHOD FOR MODULATION OF AN OPTICAL SIGNAL - The invention relates to an apparatus and a method for modulation of an optical signal with a data signal, said apparatus ( | 12-15-2011 |
20120039617 | PHOTONIC QUANTUM SYSTEM ALIGNMENT USING MULTIPLE BEAMS - A handheld device ( | 02-16-2012 |
20120063786 | CLOCK RECOVERY WITH CHANNEL COEFFICIENTS - In a coherent optical receiver of an optical communications network, a method of recovering a clock signal from a high speed optical signal received through an optical link. A set of compensation vectors are adaptively computed for compensating Inter-symbol Interference (ISI) due to at least polarization impairments of the optical signal. A channel delay is estimated based on the computed compensation vectors. The estimated channel delay is subtracted from the computed compensation vectors to generate corresponding modified compensation vectors. Finally, the modified compensation vectors are used to derive a recovered clock signal. | 03-15-2012 |
20120082464 | COHERENT OPTICAL RECEIVING APPARATUS, COHERENT OPTICAL COMMUNICATIONS SYSTEM EMPLOYING SAME, AND COHERENT OPTICAL COMMUNICATIONS METHOD - With respect to a coherent optical receiving apparatus, a polarization multiplexing light signal, whereupon a first signal is placed upon a first polarized wave light and a second signal is placed upon a second polarized wave light, is polarization divided upon the transmitting side thereof, and the first signal and the second signal cannot be received in correspondence with the transmitting side. Accordingly, disclosed is a coherent optical receiving apparatus, comprising a coherent light receiving unit that detects coherent light, and a signal processing unit that carries out signal processing that is set with control coefficients. The coherent light receiving unit receives a first polarized light that is modulated with a first transmitted signal and outputs a first detected signal, and simultaneously receives the first polarized light with a second polarized light that is modulated with a second transmitted signal, and outputs a second detected signal. The signal processing unit establishes a first control coefficient on the basis of the first detected signal, and establishes a second control coefficient on the basis of the first control coefficient and the second detected signal, and employs the second control coefficient to output a first received signal corresponding to the first transmitted signal, and a second received signal corresponding to the second transmitted signal. | 04-05-2012 |
20120134682 | METHOD AND APPARATUS FOR CLEARING AN OPTICAL CHANNEL - A method and apparatus for clearing an optical channel for transmitting data through free space between a first and second location includes a light beam, wherein the light beam has a spatially and/or time-dependent modulated intensity profile, and is substantially collimated so that the intensity profile is conserved over a specified distance of operation. The light beam includes a cross-sectional profile having regions of low and high intensity, portions of which are provided for the transmission of an optical data signal. A light source wavelength and intensity are selected for types of obscurant particles having optical properties whereby the radiation pressure acts on the particles, and the particles may then be either attracted into or repelled from portions of the spatially modulated optical beam, leaving certain portions of the optical channel beam absent of obscurant particles, thereby enabling transmission of optical data through the cleared optical channel with low attenuation. | 05-31-2012 |
20120177382 | WIRELESS DATA INTERFACE WITH MULTIPLE, INDEPENDENT TRANSMISSION SOURCES - A plurality of optical transmission sources data provides data communication from a transmitting module to a common detector cooperative with a receiving module, the modules being subject to relative rotation about a shared axis. The detector can be located on the shared axis, each of the sources directing a beam onto the detector regardless of relative module orientation, and/or the light can be diffused, so that it is detected regardless of source and detector placement and relative module orientations. Transmissions can be distinguished according to synchronized timing, differing optical frequencies, differing baud rates, and/or differing circular polarizations. The detector can split the light into a plurality of beams which pass through different optical filters and are thereby distinguished. Cut-off circuits can prevent failed sources from transmitting. A diffused second light source and a second plurality of detectors can provide reverse communication from the receiving module to the transmitting module. | 07-12-2012 |
20120183305 | METHOD AND SYSTEM FOR MONITORING OPTICAL CHANNELS - In accordance with one embodiment of the present disclosure, a system for optical signal dispersion and parameter monitoring comprises a tunable filter configured to filter a portion of one channel of an optical signal. The system comprises a polarization beam splitter configured to split the portion into first and second polarization beams and further comprises first and second photodetectors configured to respectively convert the first and second polarization beams into first and second electrical signals. Also, the system comprises a control unit configured to determine optical dispersion in the portion based on the first and second electrical signals when the portion includes a test signal. The control unit is configured to determine optical signal parameters of the portion such as channel power, channel wavelength, optical spectrum analysis (OSA) and optical signal-to-noise ratio (OSNR) based on the first and second electrical signals when the portion does not include the test signal. | 07-19-2012 |
20120189318 | DIGITAL DEMODULATOR ARCHITECTURE - Methods, systems, and devices are described for a digital demodulator device for processing received optical signals. The device may include a quadrature error filter that receives a digitized version of an optical signal, and removes quadrature errors to generate a filtered series of data samples. The device may also include a frequency offset removal module for performing frequency rotation on the filtered series of data samples. The device may include a chromatic dispersion compensation module which removes chromatic dispersion from horizontal and vertical polarization channels. The device may include a polarization mode dispersion (PMD)/polarization dependent loss (PDL) compensation module which compensates for interference caused by PMD and PDL. The device may also include a phase recovery module configured to track and correct phase. | 07-26-2012 |
20120189319 | ADAPTIVE PMD EQUALIZER AND IMPLEMENTATION - Polarization mode dispersion (PMD) in a dual-pole optical communications network is compensated for using an adaptive PMD equalizer. The PMD equalizer may include a number of substantially identical filter modules that provide partial outputs which may be combined to form a PMD compensated output. A constant modulus algorithm (CMA)-based equalizer may track PMD across both poles and generates an error signal. The CMA-based equalizer includes a filter bank, and uses an update algorithm and tap/output adjustments based on a difference between combined tap energies and an index, and feedback from a forward error correction code frame synchronizer. | 07-26-2012 |
20120224862 | System, Method, and Apparatus for High-Sensitivity Optical Detection - An apparatus receives data encoded in a format where information bits for transmission are mapped into symbols each carrying a plurality of bits, some of which are encoded through a pulse position modulation (PPM) format and the rest of which are encoded through an additional modulation format on at least one PPM pulse. The receiver detects the signal through a dual-polarization coherent receiver front-end, and recovers polarization components of the signal by decoding a first non-zero portion of a plurality of bits carried by a symbol based on slot position of at least one PPM pulse in the polarization components and a second non-zero portion of the plurality of bits carried by the symbol based on the additional modulation carried by at least one PPM pulse in the polarization components. Pilot-assisted single-carrier frequency-division equalization (PA-SC-FDE) may be used for reliable signal reception in the presence of severe PPM errors. | 09-06-2012 |
20120257902 | Device and Method for Optical Beam Combination - An optical apparatus includes a first beam combining device arranged to receive a first optical beam having a first wavelength at a first location and a second optical beam output having a second wavelength at a second location. The second optical beam has a polarization that is substantially orthogonal to a polarization of the first optical beam. The first beam combining device configured to output a first combined beam that comprises a combination of the first optical beam and the second optical beam. An optical element is arranged to receive the first combined beam and a second combined beam and to transmit an output beam that includes a combination of the first combined beam and the second combined beam. | 10-11-2012 |
20120275797 | POLARIZATION SCATTERING COMPENSATION DEVICE AND POLARIZATION SCATTERING COMPENSATION METHOD - Polarization scattering compensation device and method are disclosed. In the device, a time sequence alignment unit aligns time sequences of signals in the first and second polarization state transmitted simultaneously; a polarization scattering estimation unit estimates a scattering coefficient of a scattering by the signal in the first polarization state on the signal in the second polarization state, and a scattering coefficient of a scattering by the signal in the second polarization state on the signal in the first polarization state; and a polarization scattering removal unit removes the scattering by the signal in the first polarization state on the signal in the second polarization state, and the scattering by the signal in the second polarization state on the signal in the first polarization state, in accordance with the scattering coefficients. | 11-01-2012 |
20130028611 | Apparatuses for Reducing the Sensitivity of an Optical Signal to Polarization and Methods of Making and Using the Same - Methods and apparatuses for reducing the sensitivity of an optical signal to polarization. The method generally includes (i) reflecting the optical signal from a first mirror at a first angle relative to the optical signal to a second mirror at a second angle, and (ii) further reflecting the reflected optical signal from the second mirror to a receiver. The apparatus generally comprises (i) a first mirror at a first angle relative to an incident optical signal and configured to reflect the incident optical signal, (ii) a second mirror at a second angle configured to further reflect the reflected optical signal to a first receiver, and (iii) a lens configured to focus and/or collimate the optical signal or the reflected optical signal. The first angle is configured to reduce polarization of the reflected optical signal, thereby maximizing the intensity or power of the optical signal. | 01-31-2013 |
20130089339 | System, Method And Apparatus For High-Sensitivity Optical Detection - An apparatus receives data encoded in a format where information bits for transmission are mapped into symbols each carrying a plurality of bits, some of which are encoded through a frequency-shift keyed (FSK) format and the rest of which are encoded through an additional modulation format on at least one FSK carrier. The receiver detects the signal through a dual-polarization coherent receiver front-end, and recovers polarization components of the signal by decoding a first non-zero portion of a plurality of bits carried by a symbol based on frequency slot position of at least one FSK carrier in the polarization components and a second non-zero portion of the plurality of bits carried by the symbol based on the additional modulation carried by at least one FSK carrier in the polarization components. Pilot-assisted orthogonal frequency-division de-multiplexing (PA-OFDM) may be used for spectrally-efficient signal reception, even in the presence of severe FSK errors. | 04-11-2013 |
20130202314 | METHOD FOR TRANSMITTING INFORMATION USING PHOTONS (VARIANTS) - The invention relates to communications engineering and can be used in the transmission of information remotely on the basis of non-local quantum correlation between quantum particles, some of which are photons. The technical result to which the proposed invention (variants thereof) is directed consists in increasing the reliability of information transmission from a transmitting side to a receiving side of a communications channel. This technical result for the basic variant embodiment of the method for transmitting information using quantum particles is achieved in that, for each particle in a pair emitted by a coherent source of quantum particles, spatial paths, which are directed towards the transmitting and receiving sides, for the propagation of a superimposed state are formed with the possibility of producing mutual interference between the paired particles both on the transmitting and on the receiving side, wherein, corresponding to the binary signal transmitted, modulation on the transmitting side is performed with the aid of a physical action which changes the condition for the propagation of quantum particles in such a way that, in the case of a first value of said signal, there is a disruption to the interference pattern, while in the case of a second value of said signal, the interference pattern is restored on the receiving side, and, on the receiving side, the recovery of information is produced on the basis of the presence or the absence of the interference pattern | 08-08-2013 |
20130259490 | PROCESSING DATA IN A COHERENT OPTICAL COMMUNICATION SYSTEM - This disclosure describes techniques to sample electrical data streams in coherent receivers. For instance, an analog-to-digital converter (ADC) samples the received electrical data stream at a sampling rate that is nominally twice or greater than twice the symbol rate of the electrical data stream that the ADC receives. A digital filter receives the digital data stream from the ADC, and digitally filters the digital data streams to output a filtered digital electrical data stream at an effective sampling rate that is less than the sampling rate and less than twice the symbol rate, and greater than or equal to the symbol rate. | 10-03-2013 |
20130343766 | OPTICAL COMMUNICATION SYSTEM AND METHOD - A method for an optical communication system and an optical communication system comprising a pump source configured to generate a pump signal having rotating polarization, a polarization sensitive receiver for receiving the optical signal having a polarization tracking cut-off frequency, wherein the polarization of the pump signal is configured to rotate at a predetermined frequency of polarization rotation and the frequency of polarization rotation of the pump signal is higher than the polarization tracking cut-off frequency of the receiver. Suitable for mitigation of cross -polarization modulation (XPolM) related effects in coherent polarization multiplexed quadrature phase shift keying (CP-QPSK) systems. | 12-26-2013 |
20140079408 | COEFFICIENT DETERMINING APPARATUS, EQUALIZER, RECEIVER AND TRANSMITTER - Embodiments of the present invention provide a coefficient determining apparatus, equalizer, receiver and transmitter. The coefficient determining apparatus comprises: a synchronizer configured to find a position of a training sequence from signals containing the training sequence received by a transmitter; and a first processor configured to set an initial tap coefficient of an equalizer according to the received signals and the training sequence; wherein in each polarization state, the training sequence comprises n pairs of training symbols, in the n pairs of training symbols, the training symbols of the same pair being identical, the training symbols of the different pair being different, a cyclic prefix and a cyclic postfix being respectively inserted before and after each pair of training symbols, and n being an integer greater than 1. By using the training sequence contained in the transmitted signals to determine an initial tap coefficient of the equalizer relatively close to the optimal value, channel damages may be approximately compensated, and the receiver is facilitated in further processing the signals. | 03-20-2014 |
20140099126 | Pair-wise Symbol Correlated High Receiver Sensitivity Modulation Format - The invention is directed to a novel computer implemented method for finding a modulation format that has better receiver sensitivity than modulation formats that are currently being used, with a correlated symbol modulation in which neighboring symbols are coded and decoded together to increase receiver sensitivity. | 04-10-2014 |
20140099127 | Optical Phase Conjugation Aided Long-Haul Transmission System with Enhanced Signal-to-Noise Ratio and Nonlinear Tolerance - A long haul transmission system uses a digital signal processor DSP instead of an additional optical phase conjugate copier because the optical phase conjugate copier requires high quality optical carrier regeneration to recover the pump and optical PLL to maintain phase matching between signal and pump. Therefore, the use of DSP to process the signal and idler at receiver end greatly simplifies the system setup, increases the system stability and decreases the system cost. | 04-10-2014 |
20140126916 | OPTICAL TRANSMISSION SYSTEM, OPTICAL TRANSMITTER, OPTICAL RECEIVER, AND OPTICAL TRANSMISSION METHOD - An optical transmission system includes an optical transmitter, an optical receiver, and an optical transmission path connecting the optical transmitter and the optical receiver, wherein the optical transmitter has a first polarization scrambler to change a polarization state of an optical transmission signal in a first direction at a first polarization scrambling frequency synchronized with a transmission signal frequency, and the optical receiver has a second polarization scrambler to change a polarization state of an optical signal received from the optical transmission path at a second scrambling frequency synchronized with a received signal frequency in a second direction opposite to the first direction. | 05-08-2014 |
20140133865 | OPTICAL MODULATION SCHEMES HAVING REDUCED NONLINEAR OPTICAL TRANSMISSION IMPAIRMENTS - A method of transmitting a data signal using an optical transmitter of an optical communications system. The optical transmitter is configured to modulate an optical carrier in successive signalling intervals to generate an optical signal. A modulation scheme is provided which comprises a multi-dimensional symbol constellation. The modulation scheme is designed such that an average degree of polarization of a modulated optical signal output from the optical transmitter has a first value when averaged across a first signalling interval, and has a second value when averaged across more than one and fewer than 100 signalling intervals. The second value is less than 10 percent of the first value. During run-time, an encoder of the optical transmitter encoding a data signal to be transmitted as symbols of the constellation, and a modulator of the optical transmitter modulating available dimensions of the optical carrier in accordance with the symbols. | 05-15-2014 |
20140205301 | MODULATION UNIT - A modulation unit for a quantum communication system, wherein said modulation unit comprises an optical component configured to cause a delay between photons with different polarisation modes and a phase modulator, the optical component comprising a birefringent optical material, wherein the birefringent optical material supports the transmission of photons with a first polarisation mode and a second polarisation mode, wherein the optical path length for photons propagating with the first polarisation mode is different to the optical path length of photons propagating with the second polarisation mode, photons with the first polarisation mode having an orthogonal polarisation to those with the second polarisation mode, the phase modulator being configured to apply a further phase difference between photons with the first and second polarisation mode which pass through said modulation unit. | 07-24-2014 |
20140212149 | SOFT DECODING OF DATA IN A COHERENT OPTICAL RECEIVER - In a coherent optical receiver receiving a polarization multiplexed optical signal through an optical communications network, a method of compensating noise due to polarization dependent loss (PDL). A Least Mean Squares (LMS) compensation block processes sample streams of the received optical signal to generate symbol estimates of symbols modulated onto each transmitted polarization of the optical signal. A decorrelation block de-correlates noise in the respective symbol estimates of each transmitted polarization and generating a set of decorrelated coordinate signals. A maximum likelihood estimator soft decodes the de-correlated coordinate signals generated by the decorrelation block. | 07-31-2014 |
20140270803 | OPTICAL TRANSMISSION USING POLARISATION DIVERSITY - Method, transmitter, receiver, and system for communicating information carried by a polarization divided optical signal in an optical fiber, comprising: producing and transmitting a polarization divided optical signal OTApol comprising optical sideband pairs SBLA, SBHA each having one sideband SBLA at a first polarization and an other sideband SBHA at a second polarization that is orthogonal to the first polarization, the one sideband and the other sideband carry the same set of information A; and receiving and detecting the polarization divided optical signal OTApol to produce an electrical signal RFApol corresponding to the polarization divided optical signal; down converting the electrical signal to produce, for each sideband pair, a first converted signal BBLA corresponding to the one sideband SBLA and a second converted signal BBHA corresponding to the other sideband SBHA; and extracting the set of information A for each sideband pair using a polarization diversity scheme. | 09-18-2014 |
20150333839 | OPTICAL INTERCONNECT IN SPIN-BASED COMPUTATION AND COMMUNICATION SYSTEMS - Techniques are described for data transfer in spin-based systems where digital bit values are represented by magnetization states of magnetoresistive devices rather than voltages or currents. For data transmission, a spin-based signal is converted to an optical signal and transmitted via an optical transport. For data reception, the optical signal is received via the optical transport and converted back to a spin-based signal. Such data transfer may not require an intervening conversion of the spin-based signal to charge-based signal that relies on voltages or currents to represent digital bit values. In addition, techniques are described to use magnetoresistive devices to control the amount of current or voltage that is delivered, where the magnetization state of the magnetoresistive device is set by an optical signal. | 11-19-2015 |
20160028481 | SIGNAL EQUALIZER IN A COHERENT OPTICAL RECEIVER - A signal equalizer for compensating impairments of an optical signal received through a link of a high speed optical communications network. At least one set of compensation vectors are computed for compensating at least two distinct types of impairments. A frequency domain processor is coupled to receive respective raw multi-bit in-phase (I) and quadrature (Q) sample streams of each received polarization of the optical signal. The frequency domain processor operates to digitally process the multi-bit sample streams, using the compensation vectors, to generate multi-bit estimates of symbols modulated onto each transmitted polarization of the optical signal. The frequency domain processor exhibits respective different responses to each one of the at least two distinct types of impairments. | 01-28-2016 |
20160105236 | Hitless, Multi-Rate Optical Transmission And Reception - An apparatus comprising a processing unit configured to encode a data sequence in a plurality of modulation formats to produce a multi-rate data stream, wherein a first of the modulation formats provides a first transmission data rate, and wherein a second of the modulation formats provides a second transmission data rate different from the first transmission data rate, and insert a rate change signaling block into the multi-rate data stream to indicate a rate change from the first transmission data rate to the second transmission data rate, and a frontend coupled to the processing unit and configured to convert the multi-rate data stream into an optical signal, and transmit the converted optical signal towards a remote optical receiver via an optical network. | 04-14-2016 |
20160149666 | TRANSMISSION DEVICE, RECEIVING DEVICE, AND COMMUNICATION METHOD - An apparatus which transmits data and control information which indicates at least one of a demodulation method and a decoding method of the data using an optical signal, includes: a modulator configured to perform modulation in which a rate of change of a polarization state of light is changed according to the control information, and modulation in which a characteristic of light which is different from the rate of change of the polarization state is changed in accordance with the data; and an emitting section configured to emit light, on which modulation is performed using the modulator, to another communication apparatus via a free space. | 05-26-2016 |