| Class / Patent application number | Description | Number of patent applications / Date published |
|---|
| 398204000 | Heterodyne | 17 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 398205000 | Including polarization | 7 |
| 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 |
| 398207000 | Specific optical elements | 1 |
| 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 |
