Abstract: A method and structure for a coherent optical receiver device. Timing recovery (TR) is implemented after channel dispersion (i.e., chromatic dispersion (CD) and polarization mode dispersion (PMD)) compensation blocks. This architecture provides both improves performance and reduces power consumption of the device. Also, a TR loop is provided, enabling computing, by an error evaluation module, a first sampling phase error (SPE) and computing, by a timing phase information (TPI) module coupled to the error evaluation module, a second SPE from a plurality of CD equalizer taps PMD equalizer taps. The first and second SPE are combined into a total phase error (TPE) in a combining module, and the resulting TPE is filtered by a timing recovery (TR) filter coupled to an interpolated timing recovery (ITR) module and the combining module. The ITR module then synchronizes an input signal of the coherent optical receiver according to the TPE.

Abstract: An optical coherent receiver includes an optical hybrid (OH) configured to mix signal and reference light, and two back-end optical ports. An optical equalizing network interconnects two 180° OH output ports with the two back-end optical ports so that each back-end optical port receives light from each of the two OH output ports. Optical signals from each of the two back-end optical ports are converted to electrical signals that are fed to a differential amplifier. Adjusting coupling ratios and/or optical delays in the optical equalizing network reduces an OSNR penalty of a lower-bandwidth differential amplifier.

Abstract: A signaling system is described. The signaling system comprises a transmit device, a receive device including a partial response receive circuit, and a signaling path coupling the transmit device and the receive device. The receive device observes an equalized signal from the signaling path, and includes circuitry to use feedback from the most recent previously resolved symbol to sample a currently incoming symbol. The transmit device equalizes transmit data to transmit the equalized signal, by applying weighting based on one or more data values not associated with the most recent previously resolved symbol value.

Abstract: Embodiment of the present disclosure provide an apparatus and method to monitor a change of a polarization state resulted from an optical link and an optical receiver, in which by obtaining a change matrix of response matrices at two moments, and determining a parameter characterizing a change of a polarization state resulted from an optical link according to feature values of a change matrix in a Stokes space corresponding to the response matrices. The change of the polarization state resulted from the optical link is dynamically monitored in a real-time manner, independent of a polarization state of an input signal of the optical link, and no extra hardware and control may be needed.

Abstract: An apparatus and method for optimizing dynamically the performance of an optical network, said apparatus comprising at least one learning engine adapted to update a learning model in response to network metrics of said optical network collected during operation of said optical network, wherein the updated learning model is used to generate channel rank information for network channels; and a recommendation engine adapted to change a network channel throughput, a signal path and/or a spectral location of at least one network channel based on the channel rank information generated by the learning model of said learning engine.

Abstract: Apparatus and method for digital signal constellation transformation are provided herein. In certain configurations, an integrated circuit includes an analog front-end that converts an analog signal vector representing an optical signal into a digital signal vector, and a digital signal processing circuit that processes the digital signal vector to recover data from the optical signal. The digital signal processing circuit generates signal data representing a signal constellation of the digital signal vector. The digital signal processing circuit includes an adaptive gain equalizer that compensates the signal data for distortion of the signal constellation arising from biasing errors of optical modulators used to transmit the optical signal.

Abstract: To provide a method and device capable of easily measuring the CMRR vs. frequency characteristics of an optical receiver. Light having a measurement frequency (? [hz]) is split into two different paths, and a first optical two-tone signal, which is signal light and has a frequency difference (???? [hz]), and a second optical two-tone signal, which is local light and has a frequency difference (?+?? [hz]), are obtained and input into a coherent receiver to be measured, wherein electrical signals output from the receiver are measured to obtain both the ratio of the intensity of a signal component having the frequency ???? [hz] to the intensity of a signal component having the frequency ? [hz], which corresponds to the CMRR on the signal light side, and the ratio of the intensity of a signal component having the frequency ?+?? [hz] to the intensity of the signal component having the frequency ? [hz], which corresponds to the CMRR on the local light side.

Abstract: Optical network systems and components are disclosed, including a transmitter comprising a digital signal processor that receives data; circuitry that generate a plurality of electrical signals based on the data; a plurality of filters, each of which receiving a corresponding one of the plurality of electrical signals, a plurality of roll-off factors being associated with a respective one of the plurality of filters; a plurality of DACs that receive outputs from the digital signal processor, the outputs being indicative of outputs from the plurality of filters; a laser that supplies light; and a modulator that receives the light and outputs from the DACs, and supplies a plurality of optical subcarriers based on the outputs, such that one of the optical subcarriers has a frequency bandwidth that is wider than remaining ones of the optical subcarriers, said one of the optical subcarriers carrying information for clock recovery.

Abstract: An optical signal receiver includes a processor, a memory, an input, an output, and a sampling unit in operable communication with the processor and the memory. The sampling unit includes a shift register and a clock, and is configured to receive a laser signal at the input, collect a first sample of the received input laser signal at a first time interval, determine an amplitude of the first sample, assign a first symbol of a plurality of symbols to the determined amplitude, insert the first symbol at a first insertion point within the shift register, and generate a delay value at the output based on a position of the first insertion point with respect to the output.

Abstract: Some embodiments described herein are directed to a photo sensor and a method of operating a photo sensor. In an embodiment, a photo sensor comprises a photo diode, a filter circuit, and an output circuit. The filter circuit has an input node configured to be electrically coupled to an output node of the photo diode, and has an output node. The filter circuit has an adjustable gain, and the adjustable gain is adjustable based on a signal output from the filter circuit. The output circuit has an input node configured to be electrically coupled to the output node of the filter circuit.

Abstract: An optical coherent receiver includes an optical hybrid (OH) configured to mix signal and reference light, and two back-end optical ports. An optical equalizing network interconnects two 180° OH output ports with the two back-end optical ports so that each back-end optical port receives light from each of the two OH output ports. Optical signals from each of the two back-end optical ports are converted to electrical signals that are fed to a differential amplifier. Adjusting coupling ratios and/or optical delays in the optical equalizing network reduces an OSNR penalty of a lower-bandwidth differential amplifier.

Abstract: Apparatus and method for digital signal constellation transformation are provided herein. In certain configurations, an integrated circuit includes an analog front-end that converts an analog signal vector representing an optical signal into a digital signal vector, and a digital signal processing circuit that processes the digital signal vector to recover data from the optical signal. The digital signal processing circuit generates signal data representing a signal constellation of the digital signal vector. The digital signal processing circuit includes an adaptive gain equalizer that compensates the signal data for distortion of the signal constellation arising from biasing errors of optical modulators used to transmit the optical signal.

Abstract: A symbol phase difference compensating portion (6) calculates a first phase difference which is a phase difference between a known pattern extracted from a received signal and a true value of the known pattern and performs phase compensation for the received signal based on the first phase difference. A tentative determination portion (12) tentatively determines an output signal of the symbol phase difference compensating portion (6) to acquire an estimated value of a phase. A first phase difference acquiring portion (13) acquires a second phase difference which is a phase difference between a phase of the output signal and the estimated value of the phase acquired by the tentative determination portion (12). A first phase difference compensating portion (14) performs phase compensation for the output signal based on the second phase difference.

Abstract: A coherent optical receiver capable of receiving a multiple-wavelength optical signal comprising a series of single-band optical bursts is described. Each single-band optical burst is carried by one wavelength from among a plurality of wavelengths on a predetermined spectral band. The optical receiver can include optical generation means arranged to generate a local multiple-wavelength optical oscillator consisting of a plurality of optical lines at wavelengths corresponding to the wavelengths of the optical bursts, optical mixing means arranged to mix the optical oscillator and the optical signal in order to generate at least one mixed optical signal comprising a plurality of beats between at least one of the single-band optical bursts and the optical lines of the local multiple-wavelength optical oscillator, and a detection means to filter at least one beat between said single-band optical burst and one of the optical lines of the local multiple-wavelength optical oscillator.

Abstract: There is provided a receiving device including a hardware processor configured to demodulate a signal into which a first signal and a second signal are wavelength-multiplexed, into a first baseband signal and a second baseband signal corresponding to the first signal and the second signal, respectively, extract, from the second baseband signal, a signal component of crosstalk from the second signal to the first signal, shift a frequency of the extracted signal component, and compensate for the crosstalk from the second signal to the first signal, based on the extracted signal component shifted by the frequency.

Abstract: A method of handling upstream data transmissions in a passive optical network includes determining signal power levels of a plurality of optical network units (ONUs); and scheduling transmissions of upstream data bursts of the plurality of ONUs by, assigning each of the upstream data bursts to one of two or more data burst groups based on the determined signal power levels, and selecting time intervals during which the upstream data bursts are transmitted in accordance with the two or more data burst groups such that the two or more data burst groups are scheduled to be transmitted sequentially.

Abstract: The present invention relates to signal processing in an optical receiver, in particular to equalization performed in coherent optical receivers. A multiple-input multiple-output (MIMO) equalizer receives and equalizes a plurality of real value signals, for example four sampled electrical baseband tributaries (HI, HQ, VI, VQ). The outputs of the multiple-input multiple-output (MIMO) equalizer provide equalized real or imaginary components of complex signals. The complex signals including the real and imaginary components are then each and individually equalized to remove chromatic dispersion.

Abstract: An optical transmitter includes: a light source configured to generate CW light; a drive signal generator configured to generate a drive signal; an optical modulator configured to modulate the CW light with the drive signal so as to generate a first optical signal; a combiner configured to combine the first optical signal and a second optical signal generated by using another light source; and a detector configured to detect a frequency difference between a frequency of the CW light and a center frequency of the second optical signal. The drive signal generator includes: a mapper configured to generate an electric field information signal based on input data; and a frequency controller configured to modify the electric field information signal based on the frequency difference such that the frequency of the CW light matches the center frequency of the second optical signal to generate the drive signal.

Abstract: A WDM receiver configured to apply electronic equalization processing to both dispersion-compensated and dispersion-distorted versions of the received communication signal. In an example embodiment, the receiver's DSP first generates an equalized dispersion-compensated signal corresponding to the communication signal. The DSP then performs electronic dispersion-application processing on the equalized dispersion-compensated signal to generate a dispersion-distorted version thereof. The DSP then applies decision-aided electronic equalization processing to the dispersion-distorted version of the signal, subjects the resulting equalized signal to another round of dispersion-compensation processing, and recovers the data encoded in the communication signal using the resulting dispersion-compensated signal.

Abstract: An optical communication apparatus according to an embodiment of the present invention includes: a light emitting element; a transmission driver that drives the light emitting element; a light receiving element capable of changing a multiplication factor by a bias voltage; a temperature sensor; a computing unit that calculates a drive rate of the transmission driver; and an adjusting unit that adjusts the bias voltage applied to the light receiving element. The adjusting unit adjusts the bias voltage by linear computation using a plurality of target values of the bias voltage for combinations of a plurality of temperatures and a plurality of drive rates, based on a temperature detected by the temperature sensor and a result of calculation of the drive rate.

Abstract: An apparatus includes an electronic digital signal processor having electrical inputs for receiving a first sequence of measurements of values of a transmitted modulated optical carrier received in a coherent optical receiver and having electrical outputs for a stream of determined transmitted data values demodulated therein from the first sequence. The electronic digital signal processor has first circuitry to determine phase offsets of received pilot values from the first sequence. Additionally, the electronic digital signal processor has second circuitry to correct phase offsets of received ones of the data values from the determined phases of pilot values and data values being temporally interleaved in the transmitted modulated optical carrier. A system and a method are also included.

Abstract: Method for estimating a yield of a post-layout circuit design is provided. In one aspect, a method includes obtaining a first pre-layout parameter and a second pre-layout parameter from pre-layout simulation samples of a circuit. The method also modeling a prior distribution of a first post-layout parameter and a second post-layout parameter based on the first pre-layout parameter, the second pre-layout parameter, a first hyper-parameter, and second hyper-parameter. The method further includes calculating the first hyper-parameter and the second hyper-parameter using a cross-validation, obtaining the first post-layout parameter and the second post-layout parameter based on the first hyper-parameter and the second hyper-parameter and estimating the yield of the circuit design using a non-normal distribution parameterized by the obtained first post-layout parameter and second post-layout parameter.

Abstract: A wavelength locker integrated with a silicon photonics transmission system comprising a silicon-on-insulator (SOI) substrate and an input via a power tap coupler to receive a fraction of a transmission signal with one or more frequencies from a primary output path of the silicon photonics transmission system. The wavelength locker further includes a splitter configured to split the input to a first signal in a first path and a second signal in a second path and a first delay-line-interferometer (DLI) coupled to the second path to receive the second signal and configured to generate an interference spectrum and output at least two sub-spectrums tunable to keep quadrature points of the sub-spectrums at respective one or more target frequencies. The wavelength locker is configured to generate an error signal fed back to the silicon photonics transmission system for locking the one or more frequencies at the one or more target frequencies.

Abstract: Apparatus and method for compensating for transmitter errors in an optical communication system are provided. In certain configurations herein, a receiver is provided for processing an analog signal vector representing an optical signal received from a transmitter. The receiver includes an analog front-end that converts the analog signal vector into a digital signal vector including a digital representation of an I component and a Q component of the optical signal. The receiver further includes a digital signal processing circuit configured to process the digital signal vector to recover data, and the digital signal processing circuit includes a transmitter error compensation system that compensates the digital signal vector for at least one of a transmit skew error of the transmitter or a modulator biasing error of the transmitter.

Abstract: A wavelength locker integrated with a silicon photonics transmission system comprising a silicon-on-insulator (SOI) substrate and an input via a power tap coupler to receive a fraction of a transmission signal with one or more frequencies from a primary output path of the silicon photonics transmission system. The wavelength locker further includes a splitter configured to split the input to a first signal in a first path and a second signal in a second path and a first delay-line-interferometer (DLI) coupled to the second path to receive the second signal and configured to generate an interference spectrum and output at least two sub-spectrums tunable to keep quadrature points of the sub-spectrums at respective one or more target frequencies. The wavelength locker is configured to generate an error signal fed back to the silicon photonics transmission system for locking the one or more frequencies at the one or more target frequencies.

Abstract: A clock recovery method and device relate to the field of communication; and address the problem of the non-synchronization between the sampling clock of the transmitter and the sampling clock of the receiver. The method includes calculating a clock sampling error, a signal phase error compensation value, and a residual phase error compensation value based on data obtained after polarization demultiplexing and equalizing; adjusting a sampling clock based on the clock sampling error; performing phase adjustment for the first time based on the signal phase error compensation value; performing phase adjustment for the second time based on the residual phase error compensation value. The technical scheme provided by the embodiments of the present document is adapted to a coherent data receiver, and achieve the mechanism of the three levels of error compensation.

Abstract: Embodiments of the present disclosure provide techniques and an apparatus for partitioning calibration data into line card and pluggable properties and processing the partitioned data using a processor of the line card. For example, calibration information corresponding to components in the pluggable module may be stored on the pluggable module and transferred from the pluggable optical module to the processor on the line card. The processor may combine the calibration information received from the optical module with calibration information corresponding to properties on the line card to obtain system calibration information. The system calibration information may be used to configure one or more components used to process electric signals sent to or received from the optical module.

Abstract: A method decodes an optical signal transmitted over an optical channel from a transmitter to a receiver. The receiver receives the transmitted optical signal to produce a digital signal which is filtered in the frequency domain for compensating static effects and/or dynamic effects. The filtering is performed in the frequency domain, while the frequency coefficients of the filter are updated in the time domain by updating at least some of time coefficients of the filter and transforming the time coefficients into the frequency domain.

Abstract: The invention relates to an apparatus for characterizing a chromatic dispersion of an optical receive signal, the apparatus comprising a delay means for delaying the optical receive signal by a predetermined time delay to obtain a delayed signal, the delayed signal being delayed with respect to the optical receive signal, a phase detecting means for determining a first value indicating a phase delay of the optical receive signal, and for determining a second value indicating a phase delay of the delayed signal, and a processor for determining a chromatic dispersion indicator upon the basis of the first value and the second value, the chromatic dispersion indicator characterizing the chromatic dispersion.

Abstract: An optical reception device 20 includes an electric signal generation unit 200, a linear compensation unit 301, a nonlinear compensation unit 300, and a second coefficient setting unit 400. The electric signal generation unit 200 generates an electric signal based on an optical signal received over a transmission path 30. The linear compensation unit 301 performs processing for compensating for dispersion that occurs on optical signal in the transmission path 30 to the electric signal, using a first filter coefficient. The second coefficient setting unit 400 determines a second filter coefficient for compensating for a nonlinear effect that occurs on the optical signal in the transmission path 30, using an amount of dispersion that occurs in the transmission path 30. The nonlinear compensation unit 300 performs processing for compensating the electric signal for the nonlinear effect, using the second filter coefficient that is determined by the second coefficient setting unit 400.

Abstract: A nonlinear compensation unit (300) includes a first compensation unit (350) and a second compensation unit (360). The first compensation unit (350) compensates for each of two polarization signals Ex and Ey so as to cancel a first amount of phase rotation which is the amount of phase rotation calculated based on the signal strength of the two polarization signals Ex and Ey. The second compensation unit (360) compensates for each of the two polarization signals Ex and Ey so as to cancel a second amount of phase rotation which is the amount of phase rotation calculated based on the perturbative component of the two polarization signals Ex and Ey. The first compensation unit (350) includes a strength calculation unit (302), a first filter unit (304), and a first phase modulation unit (306). The second compensation unit (360) includes a perturbative component calculation unit (316), a second filter unit (318), a second phase modulation unit (322), and a third phase modulation unit (330).

Abstract: An heterodyne apparatus and method for measuring performance parameters of a coherent optical receiver at RF frequencies is disclosed. Two coherent lights are launched into signal and LO ports of the receiver with an optical frequency offset f. One of the lights is modulated in amplitude at a test modulation frequency F. COR performance parameters are determined by comparing two frequency components of the COR output. CMRR is determined based on a strength of a direct detection spectral line at the modulation frequency relative to that of spectrally-shifted lines at (F±f). GDV information is obtained by modulating one of the lights at two phase-locked frequencies, such as F and 2F, and comparing phases of two time-domain traces corresponding to frequency components of the COR output signal at the two frequencies.

Abstract: A receiver of a pulsed light signal comprises a photodiode adapted to generate an electric current in response to this light signal, having a parasitic capacitance Cd as its characteristic; an electrical ground; and a transimpedance amplifier connected to the input of the photodiode by a linking capacitor Cliaison. It includes an attenuation pad located between the photodiode and the transimpedance amplifier, consisting of a capacitor Cp where Cp=Cd/(??1), ? being a predetermined attenuation, where ?>1.

Abstract: An optical receiver may include a digital signal processor to receive an input sample that includes transmitted data, transmitted by an optical transmitter, and nonlinear distortion. The digital signal processor may process the input sample to generate an estimated data value. The estimated data value may be an estimate of the transmitted data. The digital signal processor may remove the estimated data value from the input sample to generate a noise sample. The digital signal processor may determine a nonlinear distortion value based on the input sample, the estimated data value, and the noise sample. The nonlinear distortion value may be an estimate of the nonlinear distortion included in the input sample. The digital signal processor may remove the nonlinear distortion value from the input sample to generate an output sample, and may output the output sample.

Abstract: It is disclosed an optical coherent receiver for an optical communication network. The optical coherent receiver is configured to receive a modulated optical signal and to process it for generating an in-phase component and a quadrature component. The optical coherent receiver comprises a power adjuster in turn comprising a multiplying unit and a retroactively connected digital circuit. The multiplying unit is configured to multiply the in-phase and quadrature components by in-phase and quadrature gains, respectively, thereby providing power-adjusted in-phase and quadrature components. The digital circuit is configured to compute: a common gain indicative of a sum of the powers of the power-adjusted in-phase and quadrature components; a differential gain indicative of a difference between the powers of the power-adjusted in-phase and quadrature components; and the in-phase and quadrature gains as a product and a ratio, respectively, between the common gain and the differential gain.

Abstract: A signal reception processing apparatus includes a digital signal processing unit that calculates a first Q value based on distribution of the symbols of the demodulated signal and distance between the symbols of the demodulated signal, and an error correction unit that outputs corrected signal as a demodulation electric signal, and calculates a second Q value based on an error rate at the time of the correction, and a control unit that calculates a penalty that indicates degradation quantity of signal quality caused by a nonlinear optical effect of an optical fiber based on the first Q value and the second Q value.

Abstract: A signal decision circuit includes: a first decision circuit configured to identify a voltage level of an input signal using an average level of an amplitude of the input signal as a first threshold level; a detection circuit configured to detect an average of an amplitude absolute level based on the average level of the amplitude; a second decision circuit configured to identify a voltage level of the input signal using a second threshold level obtained by adding the average of the amplitude absolute level to the average level of the amplitude; and a third decision circuit configured to identify a voltage level of the input signal using a third threshold level obtained by subtracting the average of the amplitude absolute level from the average level of the amplitude.

Abstract: A transimpedance amplifier includes a first and a second power supply terminal for receiving a positive constant supply voltage, wherein the second power supply terminal represents a ground, and an input terminal adapted to be connected to a current source. The transimpedance amplifier further comprises a transistor comprising a control terminal and two further terminals, wherein the input terminal is connected to the control terminal of the first transistor. An inductor is connected between the first of the two further terminals of the transistor and the first power supply terminal, and a bias network is connected between the second of the two further terminals of the transistor and ground. Specifically, the transimpedance amplifier is configured such that the resistance between said first of said two further terminals of said first transistor and said first power supply terminal is small enough, such that said transimpedance amplifier operates as a differentiator.

Abstract: A frequency offset compensation apparatus includes: first FFT means for performing a discrete-time Fourier transform of an input signal; second FFT means for performing a discrete-time Fourier transform; and offset compensation means for changing an order of output data of the first FFT means according to a frequency offset compensation amount, and rearranging the output data, and then inputting the output data to the second FFT means. This makes possible a frequency offset compensation without needing a new complex multiplier or a new memory in optical communication.

Abstract: In an optical receiver which is compatible with a plurality of signal channels, it is difficult to receive signals properly because a variation in receiving light sensitivity of a photoelectric conversion unit occurs between a plurality of signal channels, therefore, an optical receiver according to an exemplary aspect of the invention includes an optical processing circuit processing input signal light to have been input and outputting a plurality of output signal light beams; and a plurality of photoelectric conversion means for receiving the plurality of output signal light beams respectively and outputting electric signals, wherein the photoelectric conversion means includes an avalanche photodiode which can control a multiplication factor of an output current as the electric signal by means of an applied voltage; and the avalanche photodiode operates with a driving voltage by which the output currents in the plurality of photoelectric conversion means become almost the same.

Abstract: An optical receiver includes: a frontend circuit configured to generate a baseband signal representing a received optical signal by using local oscillator light; a frequency offset estimator configured to estimate a frequency offset of the baseband signal; a frequency offset corrector configured to correct the frequency offset of the baseband signal according to an estimation result by the frequency offset estimator; a phase recovery configured to recover a modulated phase from the baseband signal for which the frequency offset is corrected; a data recovery configured to recover transmission data according to the modulated phase recovered by the phase recovery; and a controller configured to control an operation of the frequency offset estimator according to a phase error of the baseband signal for which the frequency offset is corrected.

Abstract: A method of receiving an optical signal through an optical communication system. The optical signal is transmitted by a transmitter of the optical communication system with a predetermined State of Polarization in a succession of signalling intervals. The SoP in each signalling interval is selected to excite two orthogonal eigenvectors of Polarization Mode Dispersion (PMD) of the optical communication system. The SoP in one signalling interval may be different from the SoP in at least one other signalling interval. Modulation of the optical signal is detected in two orthogonal polarization directions. Modulation components associated with one of the two orthogonal eigenvectors are selected and used to recover data.

Abstract: The common mode rejection ratio (CMRR) decreases due to the difference in receiving intensity of the optical signal or in photoelectric conversion efficiency of the photodiode in the related coherent optical receiver, therefore, an optical receiver according to an exemplary aspect of the present invention includes a first photodiode receiving a first optical signal and outputting a positive signal; a second photodiode receiving a second optical signal and outputting a complementary signal; a differential transimpedance amplifier receiving the positive signal and outputting an amplified positive signal voltage, and receiving the complementary signal and outputting an amplified complementary signal voltage; and a gain adjustment means for adjusting a first gain of a gain of the differential transimpedance amplifier for the positive signal and a second gain of a gain of the differential transimpedance amplifier for the complementary signal.

Abstract: A chromatic dispersion compensator to receive a first set of digital signal values produced by sampling an analog signal at a first sampling rate and generate a second set of digital signal values by sampling the first set of digital signal values at a second sampling rate. The chromatic dispersion compensator applies a chromatic dispersion filter and an anti-aliasing filter to the first set of digital signal values.

Abstract: A system for processing data streams or signals includes a wave-front multiplexer configured to process first and second input signals into first and second output signals each carrying information associated with the first and second input signals, a first processing unit configured to process a third input signal carrying information associated with the first output signal into a third output signal, a second processing unit configured to process a fourth input signal carrying information associated with the second output signal into a fourth output signal, and a wave-front demultiplexer configured to process fifth and sixth input signals into fifth and sixth output signals each carrying information associated with the fifth and sixth input signals. The fifth input signal carries information associated with the third output signal, and the sixth input signal carries information associated with the fourth output signal.

Abstract: The present invention relates to a receiving apparatus 20 that receives burst signals, each including a synchronization section and a data section following the synchronization section, from a plurality of sources in a time division manner. The receiving apparatus 20 includes amplifying units 102 and 113 that amplify each burst signal; a detecting unit 116 that detects arrival of the burst signal from an output signal from the amplifying units 102 and 113; a comparing unit 104 that compares the output signal from the amplifying units 102 and 113 with a predetermined threshold value and outputs a binary signal; and a control unit 108 that sets the timings of changing a receive function during the synchronization section by adding delay times Dai and Dbi to a detection time point where the detecting unit 116 performs an output. The control unit 108 is configured to be able to change the delay times Dai and Dbi in a plurality of ways.

Abstract: A bias monitoring method and apparatus and a transmitter, the bias monitoring apparatus being used for monitoring deviation of a direct current bias point of an optoelectronic modulator and including: a first signal processing unit configured to perform first signal processing on an electric driving signal inputted into the optoelectronic modulator, so as to output a reference signal; a second signal processing unit configured to perform second signal processing on an electric output signal obtained based on an optical signal outputted by the optoelectronic modulator, so as to output a monitoring signal; and a monitoring signal calculating unit configured to calculate correlation between the reference signal and the monitoring signal, and output a calculation result of the correlation as a bias monitoring signal. The sensitivity of the bias monitoring apparatus may be improved, and complexity of hardware may be lowered.

Abstract: Signal processing means includes carrier compensation means for compensating for a phase difference and a frequency difference between signal light and local light in relation to two polarization signals, so as to generate two carrier compensated signals, symbol determination means for demodulating the two carrier compensated signals on the basis of a signal arrangement of multi-value modulation, symbol rough-determination means for demodulating the two carrier compensated signals on the basis of a signal arrangement in which the number of multi-values of the multi-value modulation is reduced, selection means for selecting either of an output of the symbol determination means and an output of the symbol rough-determination means, and coefficient setting means for updating filter coefficients of polarized wave separation means by using an output selected by the selection means.

Abstract: An optical receiver includes a semiconductor optical amplifier configured to amplify wavelength multiplexed light, an optical demultiplexer configured to demultiplex the wavelength multiplexed light amplified by the semiconductor optical amplifier into light of a plurality of signals having different wavelengths, a plurality of light-receiving elements configured to receive the signal light obtained by demultiplexing of the optical demultiplexer, a detector configured to detect an intensity of the wavelength multiplexed light of a previous stage of the optical demultiplexer, a memory configured to store an upper limit value of a drive current of the semiconductor optical amplifier corresponding to a detection result of the detector, and a controlling the drive current of the semiconductor optical amplifier by referring an output of the detector and the upper limit value.

Abstract: A communication system includes a transmitting device that transmits a signal based on pluralities of symbol coordinates on a constellation and pluralities of trajectory coordinates between respective ones of the pluralities of symbol coordinates, average coordinates of the pluralities of trajectory coordinates being different coordinates from coordinates of origin, and a receiving device that accumulates pluralities of trajectory coordinates between respective ones of the pluralities of symbol coordinates on the constellation in the signal received from the transmitting device, and estimates a phase of the signal received from the transmitting device based on a value representing a difference between average coordinates of the pluralities of trajectory coordinates accumulated and the different coordinates.