The present technology relates to a data processing device and a data processing method which can ensure high communication quality in data transmission using LDPC codes. In group-wise interleaving, an LDPC code having a code length N of 64800 bits and a coding rate r of 13/15 is interleaved in a unit of a bit group of 360 bits. In group-wise deinterleaving, a sequence of bit groups of the LDPC code which has been subjected to the group-wise interleaving is returned to an original sequence. The present technology can be applied to, for example, a case in which data transmission is performed using LDPC codes.

A circuit for detecting an optical data signal includes a photonics substrate and first and second photodiodes formed in the photonics substrate. The first photodiode is configured to receive, via an input port formed in the photonics substrate, a first portion of the optical data signal and convert light power of the first portion of the optical data signal to generate a first current based on the optical data signal. The second photodiode is configured to output a second current without receiving any portion of the optical data signal. The second current corresponds to a dark current induced in the second photodiode. The circuit is configured to subtract the second current from the first current to generate an output signal corresponding to a power of the optical data signal without dark current induced in the first photodiode.

Provided is an optical transmission device including: a symbol demapping unit; a likelihood generation circuit configured to generate likelihoods relating to the reception signal; and an error correction decoding unit configured to execute soft decision decoding. The likelihood generation circuit includes: a first one-dimensional-modulation lookup table configured to input the signal of the I-axis component as an argument to output a first likelihood; a second one-dimensional-modulation lookup table configured to input the signal of the Q-axis component as an argument to output a second likelihood; and a two-dimensional-modulation lookup table configured to input, as an argument, the signal being the concatenation of the signal of the I-axis component and the signal of the Q-axis component, to generate a third likelihood. The error correction decoding unit is configured to execute the soft decision decoding based on the first likelihood, the second likelihood, and the third likelihood.

Real-time systems and methods prevent duplication of independent signal streams in a coherent receiver subject to source separation controlled by multiplicative coefficients under adaptive feedback control. In various embodiments, this is achieved by first obtaining a first set of coefficients associated with a first signal stream and a second set of coefficients associated with a second signal stream. In response to the sets of coefficients satisfying a condition, the first set modified into a set of coefficients that is mutually orthogonal with respect to and replaces the second set of coefficients. The resulting series of coefficient values may then be used to perform source separation of independent signal streams without duplicating independent signal streams.

A method for phase compensation in an optical communication network includes (1) modifying a modulated signal according to one or more correction factors to generate a compensated signal, to compensate for phase rotation, (2) modulating a magnitude of an optical signal in response to a magnitude of the compensated signal, and (3) modulating a phase of the optical signal, after modulating the magnitude of the optical signal, in response to a phase of the compensated signal.

The disclosure relates to a method, an optical receiver and an optical system for compensating, at an optical receiver, signal distortions induced in an optical carrier signal by a periodic copropagating optical signal, wherein the optical carrier signal and the copropagating signal copropagate at least in part of an optical system or network, by: receiving, at the optical receiver, the optical carrier signal, wherein the optical carrier signal is distorted by the copropagating signal; determining, at the optical receiver, a period of a periodic component of the distorted optical carrier signal; determining, at the optical receiver, a periodic distortion of the distorted optical carrier signal; and generating a compensation signal to correct the distorted optical carrier signal according to the determined periodic distortion.

Dynamic error-quantizer tuning systems and methods prevent misconvergence to local minima by using a dynamic quantizer circuit that controls reference voltages of three or more comparators that are independently adjusted to modify the transfer function of the dynamic quantizer circuit. A weighted sum of the comparator outputs is subtracted from the input to form an error signal in a control loop. The ratio of the reference voltages is chosen to reduce or eliminate local minima during a convergence of the control loop and is set to values that minimize a mean squared error signal with respect to discrete modulation states of the input after the convergence of the control loop is complete.

An optical reception device includes a nonlinear optical compensation section which performs compensation of wavelength dispersion of a received signal obtained by receiving an optical signal according to a coherent detection method and compensation of a nonlinear optical effect of the received signal N (N is an integer of at least 1) step(s), and a coefficient update section which updates a coefficient so as to optimize the coefficient used in each step of the nonlinear optical compensation section based on a signal having been subjected to the compensation by the nonlinear optical compensation section and a predetermined training signal.

A receiver is configured to extract a clock signal superimposed on a detection signal of light propagated to determine whether or not SNR of the detection signal is lower than SNR at which the detection signal can be demodulated; compensate a signal value of the detection signal by using a filter coefficient and output a detection signal after signal value compensation; and calculate, as the filter coefficient, a filter coefficient in which a signal value of a detection signal output from the adaptive filter is a reference value when it is determined that there is no SNR degradation, and changes the filter coefficient to a stored filter coefficient when it is determined that SNR degradation occurs.

A coherent receiver includes a receive signal path including i) an input configured to connect a receive signal, ii) one or more signal paths connected to the input and to one or more optical hybrids, and iii) a variable optical attenuator (VOA) in each of the one or more signal paths; and a local oscillator (LO) signal path including i) an input configured to connect to an LO and the one or more optical hybrids, and ii) one or more complementary VOAs located between the input and the one or more optical hybrids, wherein the one or more complementary VOAs are configured to cancel any phase changes from the VOA in each of the one or more signal paths. The VOA in each of the one or more signal paths and the one or more complementary VOAs can be p-i-n junctions.