A system for converting digital data into a modulated optical signal, comprises an electrically controllable device having M actuating electrodes. The device provides an optical signal that is modulated in response to binary voltages applied to the actuating electrodes. The system also comprises a digital-to-digital converter that provides a mapping of input data words to binary actuation vectors of M bits and supplies the binary actuation vectors as M bits of binary actuation voltages to the M actuating electrodes, where M is larger than the number of bits in each input data word. The digital-to-digital converter is enabled to map each digital input data word to a binary actuation vector by selecting a binary actuation vector from a subset of binary actuation vectors available to represent each of the input data words.

A transmitter is provided that transmits data in either a quasi-DP-BPSK (QDP) mode or in a DP-QPSK mode. In the QDP mode, data bits are transmitted as changes in phase between first and second phase states along a first axis or as changes in phase between third and fourth phase states along a second axis in the IQ plane. A sequence bit identifies which axis carries the data bit. The sequence bit is one of a series of sequence bits that may be generated by a pseudo-random number generator. The series of sequence bits can be relatively long to permit sufficiently random changes in the axis that carries the data. Thus, unlike conventional BPSK, in which data is transmitted between phase states along a single axis, the present disclosure provides an apparatus and related method for randomly selecting one of two axes, for example, for each transmitted bit.

In some embodiments, an apparatus includes an optical transmitter module that can be electrically coupled to an electrical serializer/deserializer and a controller. The optical transmitter module can include an electrical detector that can receive an in-band signal. The electrical detector can send to the controller a first power error signal and a second power error signal based on the in-band signal. The controller can send a correction control signal to the electrical serializer/deserializer based on the first power error signal and the second power error signal such that the electrical serializer/deserializer sends a pre-emphasized signal to the optical transmitter module based on the correction control signal. In such embodiments, the first power error signal, the second power signal and the correction control signal are out-of-band signals.

An apparatus for generating a processed optical signal includes a first laser configured to emit a first optical signal in response to a first drive signal. The first optical signal has a first phase shift depending on a first integrated amplitude of the first drive signal. The apparatus also includes a spectral-temporal filter, in optical communication with the first laser, to change a first spectral profile and a first temporal profile of the first optical pulse so as to generate the processed optical signal. Replacing a conventional continuous-wave (CW) laser and external modulation with filter-based modulation can achieve the same or better performance without high-fidelity low-noise input signals.

In example implementations, an apparatus includes a serializer, a re-timing buffer coupled to the serializer, and a plurality of segments coupled to the re-timing buffer. The plurality of segments may be used for controlling a timing of an electrical signal. Each one of the plurality of segments may include a segment serializer, a timing control coupled to the segment serializer and a driver coupled to the timing control. In addition, a phase clock may be coupled to the segment serializer and the timing control of each one of the plurality of segments.

Disclosed herein is a dual parallel Mach-Zehnder-modulator (DPMZM) device comprising a DPMZM 10 having first and second inner MZMs arranged parallel to each other. The first inner MZM generates an in-phase component E.sub.I of an optical signal in response to a first driving voltage V.sub.I, and the second inner MZM generates a quadrature component E.sub.Q of said optical signal in response to a second driving voltage V.sub.Q. Further disclosed is a calculation unit 52 configured for receiving an in-phase component y.sub.I and a quadrature component y.sub.Q of a desired base-band signal, and for calculating pre-distorted first and second driving voltages V.sub.I, V.sub.Q. The calculation of the pre-distorted first and second driving voltages V.sub.I, V.sub.Q is based on a model of said DPMZM 10 accounting for I-Q cross-talk, and using an algorithm that determines said first and second driving voltages V.sub.I, V.sub.Q each as a function of both of said in-phase and quadrature components y.sub.I, y.sub.Q of said base-band signal.

A system and method for a high-speed transmitter comprising a precoder configured to receive a sequence of input symbols and to generate for each received symbol a respective recoded symbol is disclosed. The transmitter includes a recoding unit configured for recoding each current received PAM-M based on the recoded symbol immediately preceding the current recoded symbol at the recoding unit, a shift unit configured for determining a shift value for each current received symbol from the recoding unit based on the symbol received from the recoding unit and immediately preceding the current symbol at the shift unit; and Feed-Forward Equalizer unit for applying the shift values to the respective symbols received from the recoding unit to generate a corresponding sequence of output symbols to be transmitted in an output stream.

An optical transmitter apparatus is disclosed. The apparatus includes a processor, a memory coupled to the processor, and one or more programs configured to be executed by the processor. The programs include instructions for nonlinearity estimation that characterizes nonlinearity in an optical communication and estimates an amount of symbol distortion caused by the nonlinearity, instructions for selecting and mapping symbols to provide, for the nonlinearity estimation, only symbols that meet predetermined nonlinearity criteria, and instructions for storing, in the memory, the amount of symbol distortion to be used for a nonlinearity pre-compensation.

A system for converting digital data into a modulated optical signal, comprises an electrically controllable device having M actuating electrodes. The device provides an optical signal that is modulated in response to binary voltages applied to the actuating electrodes. The system also comprises a digital-to-digital converter that provides a mapping of input data words to binary actuation vectors of M bits and supplies the binary actuation vectors as M bits of binary actuation voltages to the M actuating electrodes, where M is larger than the number of bits in each input data word. The digital-to-digital converter is enabled to map each digital input data word to a binary actuation vector by selecting a binary actuation vector from a subset of binary actuation vectors available to represent each of the input data words.

Disclosed herein is a dual parallel Mach-Zehnder-modulator (DPMZM) device comprising a DPMZM 10 having first and second inner MZMs arranged parallel to each other. The first inner MZM generates an in-phase component E.sub.I of an optical signal in response to a first driving voltage V.sub.I, and the second inner MZM generates a quadrature component E.sub.Q of said optical signal in response to a second driving voltage V.sub.Q. Further disclosed is a calculation unit 52 configured for receiving an in-phase component y.sub.I and a quadrature component y.sub.Q.sub._ of a desired base-band signal, and for calculating pre-distorted first and second driving voltages V.sub.I, V.sub.Q. The calculation of the pre-distorted first and second driving voltages V.sub.I, V.sub.Q is based on a model of said DPMZM 10 accounting for I-Q cross-talk, and using an algorithm that determines said first and second driving voltages V.sub.I, V.sub.Q each as a function of both of said in-phase and quadrature components y.sub.I, y.sub.Q of said base-band signal.