Class / Patent application number | Description | Number of patent applications / Date published |
398204000 | Heterodyne | 22 |
20080205905 | DIGITAL PHASE ESTIMATOR, DIGITAL PHASE LOCKED LOOP AND OPTICAL COHERENT RECEIVER - The present invention provides a digital phase estimator, a digital phase locked loop and an optical coherent receiver. The optical coherent receiver comprises a local oscillator laser, for supplying a local oscillator optical signal; an optical 90 degree frequency mixer, for mixing a received optical signal with the local oscillator optical signal; first and second balancing photoelectric detectors, for converting the optical signals outputted from the optical 90 degree frequency mixer into baseband electrical signals; first and second A/D converters, for respectively converting output signals from the first and the second balancing photoelectric detectors into digital signals; a digital phase locked loop, for compensating a phase difference between a carrier signal of the received optical signal and the local oscillator optical signal, and outputting the compensated signal; and a data recovering unit, for recovering data from the compensated signal. | 08-28-2008 |
20080232823 | COHERENT OPTICAL COMMUNICATION APPARATUS AND METHOD - The present invention relates to a coherent optical communication apparatus and method. According to the invention, the optical communication apparatus receives a modulated optical signal, which is generated by modulating an optical signal with a first electrical signal obtained by adding a second electrical signal carrying information to be transmitted and a reference electrical signal, and converts the modulated optical signal to a third electrical signal by coherent detection. Then the apparatus detects an amount of fluctuation of the reference electrical signal included in the third electrical signal, and compensates the second electrical signal included in the third electrical signal using the amount of fluctuation. | 09-25-2008 |
20090269082 | HETERODYNE RECEIVER USING DIFFERENTIAL TEMPERATURE CONTROL OF LASER SOURCES - A heterodyne receiver includes first and second laser sources such as laser diodes which generate optical receiver oscillator (RO) signals having respective RO frequencies. Temperature control circuitry controls a temperature difference between the operating temperatures of the sources such that the RO frequencies differ by a difference frequency corresponding to the temperature difference, the difference frequency being offset from a frequency of a modulated millimeter-wave signal by a predetermined intermediate frequency. An electro-optical nonlinear mixer such as a photodiode receives the optical RO signals and the modulated millimeter-wave signal and generates an electrical intermediate-frequency (IF) signal, which is provided to an electrical amplifier/detector to detect the output signal corresponding to the modulation of the modulated millimeter-wave signal. The receiver may be used as part of a heterodyne transceiver which includes a transmitter, and the transmitter may also employ an optical heterodyne structure for generating a millimeter-wave signal for transmission. There may be sharing of some components between transmitter and receiver by dividing operation into separate transmit and receive intervals. | 10-29-2009 |
20090317092 | OPTICAL RECEIVING APPARATUS AND DIGITAL RECEIVING CIRCUIT - An optical receiving apparatus includes a combining unit that combines signal light and reference light; a optoelectric converting unit that converts, into electrical signals, two or more optical signals that enable reconstruction of a complex electric field signal of the signal light obtained by the combining unit; and a sampling clock generating unit that generates a sampling clock that has a frequency preset based on a symbol rate of the signal light and is asynchronous with the signal light. The optical receiving apparatus further includes a digital converting unit that samples at the frequency of the sampling clock signal, an electrical signal obtained by the optoelectric converting unit and converts the electrical signal into a digital signal; and a digital signal processing unit that demodulates a received signal based on a complex digital signal obtained from the digital signal obtained by the digital converting unit. | 12-24-2009 |
20100046965 | OPTICAL RECEPTION DEVICE AND OPTICAL RECEPTION METHOD - The present invention converts each of the optical differential signals from DPSK demodulator from an optical signal into an electrical signal by using optical-electrical signal converters. Thereafter, each electrical signal is subjected to amplification adjustment at an appropriate amplification factor by variable amplifier, and an appropriate delay amount is added to each electrical signal by variable delay line, and thereafter data discrimination is performed by discriminator. Since two differential signals after DPSK demodulation are subjected to amplitude and delay adjustments, the need for optical parts is obviated enabling the use of electric circuits which can be integrated. Thus, the cost of the optical reception device will be reduced. Moreover, the since electric signals whose phases and amplitudes are equalized are inputted to discriminator, erroneous determination of data at discriminator will be reduced. | 02-25-2010 |
20100111544 | OPTICAL RECEIVER FOR CONTROLLING WAVELENGTH OF LOCAL OSCILLATION LIGHT AND LOCAL OSCILLATION LIGHT CONTROL METHOD - While altering a plurality of wavelength setting parameters according to a control sequence, a local oscillation light having a wavelength controlled by those wavelength setting parameters is generated. Further, the received signal light and the generated local oscillation light are mixed, and if an electric signal is generated by photoelectric conversion from the resulting light, then the wavelength control of the local oscillation light is terminated. | 05-06-2010 |
20100135676 | Optical signal reception device and method of controlling optical signal reception - An optical signal reception device that receives and demodulates an optical signal modulated by DQPSK and performs logical inversion and other controls to transit to the object reception state. The signal reception device includes a front end including a delay interferometer and an opto-electric conversion element that receive the DQPSK optical signal and convert it into an in-phase signal and a quadrature-phase signal, a clock regenerator that regenerates a clock signal based on the in-phase signal and the quadrature-phase signal, a multiplexer that multiplexes the in-phase signal and the quadrature-phase signal, a reception frame processing unit that detects frame synchronization based on the signal multiplexed by the multiplexer and de-maps the received frames, and a controller that, based on out-of-frame-synchronization information (LOF/OOF) from the reception frame processing unit, performs logical inversion control in the clock regenerator, multiplexing timing control in the multiplexer, and controls the delay interferometer in the front end so as to transit to the object reception state. | 06-03-2010 |
20120195602 | SAMPLING CLOCK SYNCHRONIZING APPARATUS, DIGITAL COHERENT RECEIVING APPARATUS, AND SAMPLING CLOCK SYNCHRONIZING METHOD - In a sampling clock synchronizing apparatus, an A/D converter converts an analog signal to a digital signal based on a sampling clock, and a processor compensates a band limitation due to spectral narrowing by filter characteristics of characteristics opposite to those of the spectral narrowing with respect to a signal produced from the A/D converter subjected to the spectral narrowing, and detects a phase shift in the sampling clock based on a signal after the compensation of the spectral narrowing and synchronizes sampling timing. | 08-02-2012 |
20120294629 | Method for Improving the Performance of Digital Coherent Optical Receiver Using Single Ended Photo-Detection - A method and system for mitigating distortion in coherent single-ended photo-detection is disclosed. The methodology comprises: receiving an optical signal carried on an optical transmission medium and coherently detecting the received optical signal to produce a digitized signal; estimating a time-dependent random variable introducing distortion to the coherently detected signal; and subtracting the distortion from digitized signal to produce a distortion mitigated output signal. | 11-22-2012 |
20140363176 | OPTICAL PHASE COMPENSATION DEVICE, OPTICAL RECEIVER, AND OPTICAL PHASE COMPENSATION METHOD - An optical phase compensation device included in an optical receiver employing an intradyne detection method, includes a first optical phase error calculator configured to calculate a first optical phase error by averaging signal symbols of a first number of input main signals, a second optical phase error calculator configured to calculate a second optical phase error by averaging signal symbols of a second number of the main signals, wherein the second number is smaller than the first number, and a subtractor configured to subtract, from optical phase components of the main signals, one of a difference between the first optical phase error and the second optical phase error and a value obtained by multiplying the difference by a gain relative to the difference. | 12-11-2014 |
398205000 | Including polarization | 9 |
20090047030 | Coherent light receiving system - In order to reduce the size and simplify the structure of a coherent light receiver, the coherent light receiver includes an optical mixer for coupling local oscillator light and reception signal light, a photoelectric converter for photoelectrically converting light coupled in the optical mixer, a reception data processing unit for extracting reception data included in the reception signal light through digital signal processing for processing the coupled signal converted into an electrical signal by the photoelectric converter, based on a first clock, and a modulator for modulating the local oscillator light or the reception signal light inputted to the optical mixer respectively, by using a clock phase-synchronized with the first clock used for the digital signal processing in the reception data processing unit. | 02-19-2009 |
20090074427 | Reconstruction and restoration of two polarization components of an optical signal field - Digital compensation of the polarization-mode dispersion (PMD) effects experienced by an optical signal in a transmission link is achieved. A digital representation of the optical fields of two orthogonal polarization components of an optical signal, defined by a polarization beam splitter (PBS), is first obtained. The fiber transmission link is treated as a concatenation of multiple virtual PMD segments, each having two specific principle-state-of-polarization (PSP) axes and causing a differential group-delay (DGD) and a phase delay between two signal components that are polarized along the two PSP axes. The best guesses of the parameters of the PMD segments and the relative orientation between the PSP axes of the last PMD segment and the characteristic polarization axes of the PBS are dynamically obtained. The digital representation of at least one generic component of the field of the optical signal is then computed through matrix operations by using the best guesses. | 03-19-2009 |
20100221020 | Adaptive Polarization Tracking And Equalization In Coherent Optical Receivers - A method for operating an optical receiver includes at each of a sequence of sampling times, producing a first 2D complex digital signal vector whose first component is indicative of a phase and amplitude of one polarization component of a modulated optical carrier and whose second component is indicative of a phase and amplitude of another polarization component of the carrier. For each one of the sampling times, the method includes constructing a second 2D complex digital signal vector that is a rotation of the first 2D complex digital vector for the one of sampling times. The rotation compensates a polarization rotation produced by transmission of the modulated optical carrier between an optical transmitter and the optical receiver. | 09-02-2010 |
20100316393 | METHOD AND APPARATUS FOR RECEPTION OF OPTICAL SIGNALS - An apparatus and method are provided for receiving an optical signal having an optical carrier component and at least one information-bearing optical sideband. In general, an optical filter arrangement ( | 12-16-2010 |
20110033195 | POLARIZATION DIVERSITY RECEIVER SYSTEMS AND METHODS WITH POLARIZATION MODE DISPERSION MITIGATION - The present disclosure relates to polarization diversity receiver systems and methods with polarization mode dispersion mitigation through processing. Specifically, the present invention includes a direct-detection receiver system that removes the requirement for a LO and an ADC thereby improving power, size, and cost over existing solutions, while at the same time allowing sufficient electronic processing to mitigate PMD impairment. The present invention can be realized in a processing block in CMOS technology front-ended with a polarization diversity receiver utilizing a 90 deg. optical hybrid. | 02-10-2011 |
20110243575 | METHOD FOR ADAPTIVE BLIND EQUALIZATION OF PSK SIGNAL, EQUALIZER AND RECEIVER - The present application discloses a method for adaptive blind equalization of a PSK signal, an equalizer and a receiver. According to embodiments as provided, a conjugate product of a current output and a precedent output of an FIR filter is calculated, an equalization coefficient is updated using the conjugate product, and then an input signal is filtered using the FIR filter with the updated equalization coefficient. The embodiments as provided is applicable to adaptive blind equalization of any phase shift keying signal including a BPSK signal. | 10-06-2011 |
20120076507 | SINGLE PIN COHERENT RECEIVER - In a coherent optical receiver of an optical communications system, methods and systems for receiving a data signal x(t) modulated on an optical signal. A linearly polarized LO light is generated, which has a frequency of f | 03-29-2012 |
20140178081 | SIGNAL PROCESSING CIRCUIT, SIGNAL PROCESSING METHOD, OPTICAL RECEIVER AND OPTICAL COMMUNICATION SYSTEM - In order to reduce influence of noise due to a phase deviation, and to estimate an amount of phase compensation with superior accuracy in a polarization multiplexing/demultiplexing optical communication system, a signal processing circuit includes: optical frequency deviation estimating unit for estimating a frequency deviation which is a difference between a frequency of local light and a frequency of the optical carrier wave which is included in a signal data which corresponds to the polarizations and are generated by mixing a plurality of the optical carrier waves with the local light, which optical carrier wave is phase-modulated and have polarizations able to be demultiplexed and for outputting the estimated frequency deviation as an estimated value; for outputting the estimated frequency deviation as an estimated value; optical frequency deviation compensation amount analyzing unit for calculating an amount of frequency compensation which is an amount of compensation to make a phase of the signal data rotated so as to reduce the frequency deviation, on the basis of a plurality of the estimated values estimated per the signal data; optical frequency deviation compensating unit for making the phase of the signal data rotated correspondingly to the amount of the frequency compensation; optical phase deviation estimating unit for estimating a phase deviation included in each of input signal data and is a difference between a phase of the optical carrier wave and a phase of the local light; and optical phase deviation compensating unit for making the phase of the signal data rotated correspondingly to the phase deviation. | 06-26-2014 |
20150117872 | POLARIZATION DEMULTIPLEXING OF OPTICAL SIGNALS - An example embodiment includes optical receiver that includes a polarization beam splitter (PBS), a polarization controller, and a forward error correction (FEC). The PBS is configured to split a received optical signal having an unknown polarization state into two orthogonal polarizations (x′-polarization and y′-polarization). The polarization controller includes no more than two couplers and no more than two phase shifters per wavelength channel of the x′-polarization and the y′-polarization. The polarization controller is configured to demultiplex the x′-polarization and the y′-polarization into a first demultiplexed signal having an first polarization on which a data signal is modulated and a second demultiplexed signal having a second, orthogonal polarization on which a pilot carrier oscillator signal is encoded. The FEC decoder module is configured to correct a burst of errors resulting from resetting one of the phase shifters based on error correction code (ECC) data encoded in the data signal. | 04-30-2015 |
398207000 | Specific optical elements | 3 |
20120281990 | OPTICAL RECEIVER CONFIGURABLE TO ACCOMMODATE A VARIETY OF MODULATION FORMATS - The present invention provides a simple means of demodulating optical signals, e.g. wideband M-ary orthogonal. The demodulator comprises an optical processor and a comparison module. The optical processor transforms M input optical signals into 2 log | 11-08-2012 |
20140023381 | Non-Linear Optical Receiver - A method and apparatus for optical communication. A plurality of optical signals having a plurality of different frequencies is received at a receiver. The plurality of optical signals received at the receiver is sent through a non-linear optical element in the receiver such that a resulting optical signal is generated that has a frequency based on at least one of the plurality of different frequencies. Information is identified in the resulting optical signal. | 01-23-2014 |
20160036535 | HIGH EFFICIENCY COHERENT IMAGER - An extended field heterodyne detection apparatus comprises a local signal oscillator, a micro-lens array set in optical relation to the local signal oscillator to multiplex a beam from the local signal oscillator, a local oscillator injection lens in the optical path of the local oscillator and the micro-lens array, a semi-reflective beam splitter at the telecentric stop of the local oscillator injection lens to reflect the beam of the local oscillator in parallel to a signal beam passing through the semi-reflective beam splitter, an objective lens, with a stop, located at the semi-reflective beam splitter, and a focal plane array, situated to receive the source beam. The extended field heterodyne detection apparatus solves the problem of creating a local oscillator beam that is mode-matched for an incoming signal beam, for the eventual process of mixing both the signal beam and the local oscillator using a conventional, square-law detector. | 02-04-2016 |