Abstract: Methods and systems for communication with an optimized constellation include coding an input data stream to a symbol stream according to an optimized constellation that has a non-Gray bit mapping and that has neighboring points having more than one bit difference farther apart than neighboring points having one bit difference. The symbol stream is modulated onto a transmission signal and subsequently demodulated at a receiver to produce a received symbol stream. The received symbol stream is decoded to a bitstream according to an optimized constellation that has a non-Gray bit mapping and that has neighboring points having more than one bit difference farther apart than neighboring points having one bit difference.

Abstract: Systems and methods for optical communication are disclosed that include communicating data using one or more transceiver pairs coupled to a spatial-multiplexer (S-MUX); performing bi-directional transmissions over an elliptical core optical fiber to a spatial-demultiplexer (S-DEMUX) using spatial modes to communicate data in either direction between two transceiver pairs with low crosstalk and without optical circulators or wavelength-division multiplexing (WDM); and communicating data from the S-DEMUX with g one or more transceiver pairs.

Abstract: A system for centralized automatic bias control for a plurality of modulators, including a coupler for coupling output of each of the plurality of modulators to generate a combined modulator output. A pilot insertion device inserts a pilot tone into each of the plurality of modulators such that a different pilot tone frequency is inserted for each of the plurality of modulators. A monitoring device iteratively monitoring power (Pt) of each inserted pilot tone over time to determine whether a current modulator bias is optimal for each of the plurality of modulators, and an adjuster device iteratively adjusts the modulator bias for each of the plurality of modulators for which the current modulator bias is determined to be sub-optimal until a threshold condition has been met.

Abstract: A wavelength division multiplexing system and method featuring a wavelength monitor that is configured to receive a portion of a combined signal of wavelength division multiplexing channels and determine the wavelengths of each channel or the guardband between each channel in the combined signal. The wavelength monitor determines if there is excess laser drift for each channel in the combined signal. If excess laser drift is determined, feedback is sent to the transmitter for the signal with excess laser drift and the signal is adjusted to produce a target wavelength. The wavelength monitor may utilize optical intradyning in order to monitor the wavelengths of each channel in the combined signal.

Abstract: Systems and methods for optical communication are disclosed that include communicating data using one or more transceiver pairs coupled to a spatial-multiplexer (S-MUX); performing bi-directional transmissions over an elliptical core optical fiber to a spatial-demultiplexer (S-DEMUX) using spatial modes to communicate data in either direction between two transceiver pairs with low crosstalk and without optical circulators or wavelength-division multiplexing (WDM); and communicating data from the S-DEMUX with g one or more transceiver pairs.

Abstract: A method of wavelength conversion without polarization tracking is provided. A system is also provided that converts an input signal into an output signal of a different wavelength that contains all of the amplitude, phase, and polarization information of the original signal. The method includes separating, using a polarization-diversity optical mixer, an input optical signal of a first wavelength into a plurality of electrical signals containing amplitudes and phases while maintaining the polarization information of the input signal, converting each of the amplitudes and phases into individual photo-currents using a photo-diode, converting each of the output photo-currents into voltages using an amplifier, modulating the multitude of voltages to a second wavelength using a modulator, where the separated electrical signals are up-converted to generate an output optical signal that maintains the same amplitude, phase, and polarization information as was contained in the input signal.

Abstract: A system for optimizing signal quality in an optical communication system is provided including a transmitter for converting digital signals to optical signals, the transmitter including a transmitter digital signal processing chip including a pre-distortion logic and a transmitter look-up table (LUT). A receiver is operatively coupled to the transmitter for receiving and converting the optical signals from the transmitter to digital signals. The receiver includes a receiver digital signal processing chip including a correction logic and a receiver look-up table (LUT). The transmitter LUT is constructed by scaling the receiver LUT by a weight factor and is iteratively updated based on a weighted sum of the receiver LUT.

Abstract: Systems and methods are disclosed for optically communicating data by, at a transmitter side, encoding a block of input bits by one or more outer encoders, and after interleaving the encoded bits, permuting the encoded bits according to a predetermined sequence or order, and further encoding the encoded bits by an inner encoder, and at a receiver side, decoding received bits with an inner decoder, and after the encoded bits are permuted, subsequently decoding by and outer decoder, and returning information bits at an outer decoder as an output. The soft-decision and hard-decision outputs from the outer BCH code help the inner LDPC decoder to have better estimation of the received bits and gain performance. The performance in higher-order modulation formats could be as large as 0.5 dB in one embodiment.

Abstract: The present invention is directed to a controller for generating ultra-wide band electrical signals for high data-rate single optical carrier transmission. The controller includes generating a digitally jointed baseband signal with radio frequency RF up-conversion to create optical dual side bands.

Abstract: A method of transmitting a data signal is provided that includes integrating a trellis encoder/decoder into a transmitter for 16 quadrative amplitude modulation (QAM) to provide a first and second mode of modulation, wherein each mode has a same baud rate. Data is transmitted from the transmitter at the first mode of modulation with a plurality of first subcarriers with DP16QAM modulation to provide a substantially 400G data transmission rate, or data is transmitted from the transmitter at the second mode of modulation with a plurality of second subcarriers with trellis coded modulation to provide a substantially 1T data transmission rate.

Abstract: Methods and systems for communication with an optimized constellation include coding an input data stream to a symbol stream according to an optimized constellation that has a non-Gray bit mapping and that has neighboring points having more than one bit difference farther apart than neighboring points having one bit difference. The symbol stream is modulated onto a transmission signal and subsequently demodulated at a receiver to produce a received symbol stream. The received symbol stream is decoded to a bitstream according to an optimized constellation that has a non-Gray bit mapping and that has neighboring points having more than one bit difference farther apart than neighboring points having one bit difference.

Abstract: A computer implemented method for dynamic data rate adjustment within a cascaded forward error correction FEC for optical communications includes subjecting data communicated over an optical network to a forward error correction in an encoding or decoding of the data, the encoding or decoding employing a codeword, re-encoding part of the codeword for generating a subsequent codeword where an actual code rate is tuned by adjusting a size of data encoded to provide re-encoded data, and dynamically changing the re-encoded data size to achieve cascaded rate adaptive FEC for communication of the data over the optical network.

Abstract: A system for carrier phase recovery, including a receiver for receiving one or more frames of L symbols. A phase estimator performs carrier phase estimation for the received frames of L symbols, and the resulting carrier phase estimates are stored in a non-transitory computer-readable storage medium. One or more rotators de-rotates the received frames of L symbols by one or more of the carrier phase estimates, and a data processor calculates a sum of the outputs of the L de-rotated signals raised to an nth power, and determines a real part of the sum. A minimum determination device determines a minimum of the real part of the sum with respect to the carrier phase estimates, and phase unwrapping and multiplier removal is performed if a minimum has been determined.

Abstract: This invention proposes an alternative modulation format for channels that present improved performance when such channels co-propagate with existing intensity modulated channels. This modulation format is named Rhombic-QPSK (R-QPSK) and it is designed in such a way that it presents more tolerance to phase noise created by the nonlinear interaction with the legacy channels.

Abstract: Systems and methods are disclosed for data communication by performing RF sub-band multiplexing and demultiplexing by cascading a radio-frequency (RF) mixing module and optical dual-polarized (DP) QPSK modulator forhybrid RF/optical IQ modulation; and performing intra-transceiver optical superchannel switching through the RF sub-band multiplexing.

Abstract: An optical communication method includes converting an optical pulse amplitude modulation (PAM) signal to a square QAM signal using an optical delay interferometer (DI) to perform all-optical PAM to QAM conversion in the DI; performing optical de-correlation of I and Q tributaries of the QAM signal to avoid frequency dependent attenuation in RF cabling which impacts signal quality; and finding optimal phase control mechanism of the DI by monitoring and equalizing down-converted I and Q electrical signal amplitudes, using coherent detection; and emulating a square quadrature amplitude modulation (QAM) optical signal with duplicated data copies.

Abstract: Systems and methods are disclosed for receiving data by radio frequency (RF) mixing to down-convert in-phase and quadrature parts of a photo-detected electrical RF band signal to baseband for data conversion; controlling a mixing phase of a electrical local oscillator (LO) at one or more RF mixing modules; selecting one of the RF sub-bands to be down-converted to baseband after coherent photo-detection; and performing RF sub-band de-multiplexing for ultra-wide band optical digital coherent detection.

Abstract: A method includes evaluating an optical signal spectrum for estimated filtering parameters of an optical spectral filtering device for shaping optical signal spectrum, determining a feedback for fine tuning the optical spectral filtering device for nonlinearity tolerance enhancement in the optical transmission system, responsive to received optical signal quality in the optical signal spectrum; and using the feedback to adjust said optical spectral filtering device for predetermined shaping and predetermined fiber nonlinearity tolerance in the optical transmission system.

Abstract: At a receiver side, to enhance the performance of concatenated LDPC and TCM coding, an iterative decoding between TCM decoder and LDPC decoder enables improvement in the reliability of received LLRs of each symbol after each iteration. A SOVA output of the TCM is used for LDPC decoding, and then the updated LLRs from LDPC decoder are further looped back to the TCM decoder for the next iteration. In such a manner, the decoding performance could be significantly improved after just several iterations.

Abstract: A computer implemented method for a cyclic (forward-backward) decoding for a forward error-correction FEC scheme includes decoding a given k?1th codeword in a block code of length N in an optical communication system, forwarding M symbols' enhanced log likelihood ratios LLRs produced by decoding the k?1th codeword, decoding the kth codeword together with forwarded M symbols' enhanced LLRS, and feeding backward, to the initial step i) decoding, corresponding overlapped M symbols' enhanced LLRs for decoding of the k?1th codeword again.