An optical transmitter generates symbols for transmission by applying a predetermined coding method to each of m-valued transmission symbols generated from transmission data, generates signal light by performing optical modulation on the basis of the symbols for transmission, and transmits the signal light. An optical receiver generates a series of digital signals from the received signal light, detects coded symbols by applying predetermined digital signal processing to the series of digital signals, decodes the m-valued transmission symbols from the detected coded symbols, and restores the transmission data from the decoded m-valued transmission symbols. An operation based on the predetermined coding method performs nonlinear coding that generates the coded symbols by generating m-valued intermediate symbols from the m-valued transmission symbols, the nonlinear coding restricting transitions between series of the coded symbols in time series by assigning bit information to a state transition between coded symbols adjacent in time series and making a number of states that each of the coded symbols can take on greater than a number of states of the m-valued transmission symbols.

Optical fiber interconnection systems and methods are described. One aspect includes receiving a pulse-amplitude modulated (PAM4) electrical signal at a transmitter for transmission to a receiver. The PAM4 electrical signal is decoded into a pair of non-return-to-zero (NRZ) electrical signals. The pair of NRZ electrical signals is converted into a corresponding pair of NRZ optical signals including a first NRZ optical signal and a second NRZ optical signal. The first NRZ optical signal is transmitted to a receiver over an communication channel. The second NRZ optical signal is transmitted to the receiver over the optical communication channel.

A method, system, and apparatus enabled to selectively choose a baud rate for communication of optical data using a modem enabled to operate with an optical signal modulated at plurality of finely tuned baud rates.

An optical transceiver including a submount, a Mach-Zehnder Modulator (MZM), bonding wires, and a low pass filter type matching network is provided. The MZM includes an input port and an output port and disposed on the submount. The bonding wires are coupled to the submount and the MZM. The low pass filter type matching network is coupled to the bonding wires and is configured to absorb inductance of the bonding wires at a high frequency.

A sensor device includes a sensor array including a plurality of photodiodes configured to generate current signals in response to light, an encoder configured to encode the current signals to generate a plurality of analog signals and output the plurality of analog signals sequentially, a signal processing module configured to process the analog signals, received from the encoder, to generate digital signals, and a decoder configured to decode the digital signals, received from the signal processing module, to generate a plurality of data signals corresponding to the current signals.

An optical transmitter has an optical modulator having Mach-Zehnder interferometers, modulator drivers configured to drive the optical modulator by a drive signal, a low frequency generator configured to generated a low frequency signal that changes a ratio of a driving amplitude with respect to a half-wave voltage of the optical modulator, a photodetector configured to detect a portion of output light of the optical modulator, a detector configured to detect a low frequency component contained in a detected signal from the photodetector using the low frequency signal, and a bias voltage controller configured to control a bias voltage for the optical modulator such that the detected low frequency component becomes the maximum and in-phase with the superimposed low frequency signal.

An optical full-field transmitter for an optical communications network includes a primary laser source configured to provide a narrow spectral linewidth for a primary laser signal, and a first intensity modulator in communication with a first amplitude data source. The first intensity modulator is configured to output a first amplitude-modulated optical signal from the laser signal. The transmitter further includes a first phase modulator in communication with a first phase data source and the first amplitude-modulated optical signal. The first phase modulator is configured to output a first two-stage full-field optical signal. The primary laser source has a structure based on a III-V compound semiconductor.

A method for transmitting a plurality of input streams from a transmitter to a receiver processes each of a plurality of input data streams to generate a plurality of parallel pairs of data streams including an in-phase stream (I) and a quadrature-phase stream (Q) for each of the plurality of input data streams. Each of the plurality of parallel pairs of data streams are modulated with a selected one of at least three prolate spheroidal wave functions, respectively, to generate a plurality of data signals, each of the plurality of data signals associated with one of the plurality of parallel pairs of data streams. A plurality of composite data streams are generated by overlaying at least one data signal of the plurality of data signals in a first data layer with the at least one data signal of the plurality of data signals in a second data layer. The plurality of composite data streams are processed to associate with each of the plurality of composite data streams an orthogonal function to cause each of the plurality of composite data streams to be mutually orthogonal to each other on the link to enable transmission of each of the plurality of the composite data streams on the link at a same time.

An equalizer and method is implemented to improve the performance of a communication system based on multi-level amplitude modulation schemes. The equalizer may include a linear equalization circuit including a plurality of time delayed taps and configured to receive an input signal and generate an output signal. The equalizer may further include a nonlinear circuit configured to receive signals from at least a portion of the time delayed taps and generate at least a portion of a difference between the signals, the output signal based at least in part on the difference.

A Dual Parallel (DP)-Inphase/Quadrature (I/Q) Mach-Zehnder Modulator (MZM) bias controller configured to generate a pair of orthogonal dither signals; multiply the pair of dither signals to create a second order orthogonal dither signal; and lock an Inphase (I) I MZM of a DP-I/Q MZM to a value of a corresponding I component of a transmission signal by applying the pair of orthogonal dither signal to a Quadrature (Q) MZM and a Phase (P) MZM of the DP-I/Q MZM; applying an I bias signal to the I MZM of the DP-I/Q MZM; detecting an output of the DP-I/Q MZM; and determining an I error signal in the output of the I MZM of the DP-I/Q MZM based on the product of second order dither signal and the output of the DP-I/Q MZM.