Ben-gurion University of the Negev Research and Development Authority

Multiphy Ltd.

Bar-ilan University

Other

Xlight Photonics Inc.

Multiply Ltd.

Multipon Networks Ltd.

Cyberridge Ltd.

Dan Sadot

Albert Gorshtein

Guy Dorman

Yaron Yoffe

Gilad Katz

Tomer Yeminy

Zeev Zalevsky

Eyal Shekel

Daniel Majer

Nir Sheffi

Efraim Buimovich

Omri Levy

Norman S Kopeika

Gil Paryanti

Alik Gorshtein

Gilad Kats

Samuel Rubin

Yanir London

Yehezkel Joseph

Shmuel Rubin

Eyal Wohlgemuth

Ehud Barzilai

Sagie Asraf

Omri Levi

A method for transmitting data carrying optical information over an optical channel, comprising the steps of providing an optical transmitter consisting of a light source being a Mode-Locked Optical Frequency Comb (MLFC) for generating a frequency comb of multiple carriers, each of which being modulated by a baseband signal; an optical modulator for modulating each and all of the multiple carriers in a modulation bandwidth extending up to the modes' frequency spacing between the multiple carriers; performing all-optical encoding of the modulated carriers by manipulating the optical amplitude and/or phase and/or polarization of all optically modulated carriers; and transmitting, by the optical transmitter, the encoded modulated carriers to an optical receiver, over an optical channel.

Optical communication system using mode-locked frequency comb and all-optical phase encoding for spectral and temporal encrypted and stealthy transmission, and for optical processing-gain applications

A method for compensating the distortions introduced by impairments of MZMz implementing an optical transmitter, according to which the level of total amplitude and phase distortions caused by the optical transmitter is measured and all impairments in the constellation domain are compensated by pre-distorting the input signal to be transmitted by symmetrically adding imbalance to the voltage applied to the MZM arms. The imbalance is determined by introducing a phase rotation in either I or in the Q path of the optical transmitter, which compensates the total amplitude distortion, and also introducing a phase rotation to both I and Q paths of the optical transmitter, which compensate the total phase distortion and the phase shift caused by compensating the amplitude distortion, until reaching a desired operating point, which corresponds to the level of pre-distortion.

Method for compensating channel distortions by pre-distortion of Mach-Zehnder modulators, based on symmetric imbalance

Disclosed are a method for achieving ultrahigh spectral resolution and a photonic spectral processor, which is designed to carry out the method. The disclosed photonic spectral processor overcomes the current 0.8 GHz spectral resolution limitation. The new spectral processor uses a Fabry-Perot interferometer array located before the dispersive element of the system, thus significantly improving the spectral separation resolution, which is now limited by the full width at half maximum of the Fabry-Perot interferometer rather than the spectral resolution of the dispersive element spectral as is the current situation. A proof of concept experiment utilizing two Fabry-Perot interferometers and a diffractive optical grating with spectral resolution of 6.45 GHz achieving high spectral resolution of 577 MHz is described.

Ultrahigh resolution photonic spectral processor

A method for increasing the effective resolution of digital-to-analog conversion for the purpose of digital pre-distortion to compensate distortions of a communication channel, according to which a digital sequence of N samples x(n) to be transmitted over the communication channel are received and several quantization possibilities are generated by performing Soft Quantization (SQ) on each sample, using a soft quantizer, where low computational complexity is maintained by limiting the number of SQ possibilities. The Instantaneous costs for each possible SQ error is computed and converging paths in the Trellis diagram, which represents possible states and transitions between them, for each sample is eliminated. Then the averaged errors for each remaining path are computed and Hard-Quantization is performed to eliminate converging paths and to keep a constant number of states. These steps are repeated N times, one time for each sample and the optimal path with the lowest averaged error selecting. Then the sequence associated with the optimal path is fed into the DAC.

Digital resolution enhancement for high speed digital-to-analog converters

A method for optimizing non-uniform quantization thresholds of an ADC in MLSE-based receivers in an optical communication channel, according to which a Quantized Noise (QN) distortion model, in which the quantization and the channel additive noises are combined is generated. The model is applied on the channel deterministic analog states x(n) and on sequences of analog states and transition probabilities are calculated, which will be used later on to calculate the BER, from channel deterministic states and sequences of channel deterministic states into the discrete ADC quantization regions. Real value outputs of the ADC are replaced by the transition probabilities and non-uniform quantization of the ADC is performed, with thresholds that are optimized for MLSE detection, to obtain maximal statistical separation. A DSP circuit computes, the MLSE metrics and the transition probabilities of the analog states into the quantized values, for each of the channel deterministic state; and an MLSE decoder post-processes transition probabilities replacing the ADC outputs and representing analog regions, based on the derived transition probabilities.

Low resolution ADC-DSP optimization based on non-uniform quantization and MLSE for data centers interconnects

Disclosed is a method of compensating for coupling impairments in optical communication systems comprising two or more coupled transmission lines. The method comprises introducing into the system a component comprising an electronic circuit configured to realize at least one of an exact electrical coupling compensation (EECC) algorithm and a spectrally fragmented electrical coupling compensation (SF-ECC) algorithm.

Inclusive modeling and digital compensation for coupling impairments of high-speed coupled electrical microstrip traces in data center connections

A system for optimizing power allocation for each optical transmitter in an optical transmission system, the system comprises at least two intensity modulated optical transmitters, each of which is controlled by a modulator; an optical channel that can be spatially multiplexed by a multiplexer; and at least two optical detectors, for detecting the transmitted modulated signals. Each of the modulators are adapted to modulate the transmitters such that the electrical power consumption of the optical transmitters is minimized by a modulation scheme of the modulators, that uses energy efficient convex optimization to multiplex the transmitted optical signals, by the multiplexer in a multiple-input-multiple-output (MIMO) scheme. Each of the modulators are adapted to modulate the transmitters such that the capacity is maximized by a modulation scheme of the modulators, that uses energy efficient convex optimization to multiplex the transmitted optical signals, by the multiplexer in a multiple-input-multiple-output (MIMO) scheme.

Energy-efficient power and offset allocation of spatial multiplexing in multimode fiber

A method for performing optical constellation conversion, according to which each received symbol from a constellation of input symbols is optically split into M components and each component is multiplied by a first predetermined different complex weighing factor, to achieve M firstly weighted components with different amplitudes. Then a nonlinear processor optically performs a nonlinear transform on each M firstly weighted components, so as to obtain M outputs which are linearly independent, Finally, a linear processor optically performs a linear transform to obtain a new converted constellation by optically multiplying, in the complex plane, each of the M outputs by a second predetermined different complex weighing factor, to achieve M secondly weighted components and then summing the M secondly weighted components.

All-optical silicon-photonic constellation conversion of amplitude-phase modulation formats

A system for digitally equalizing a data channel with heavily ISI-induced signals received after passing a data communication channel using a combination of a linear equalizer and a nonlinear equalizer, which comprises an ADC, for sampling a received signal and converting it to a digital form; a Linear Equalizer for pre-processing said received signal, said Linear Equalizer is adapted to pre-process a first group consisting of echoes/channel taps of the induced ISI, which are not equalized by said nonlinear equalizer, by eliminating the echoes/channel taps of said first group; pre-process a second group consisting of the combination of the entire echoes/channel taps of the induced ISI, by eliminating the echoes/channel taps of said second group; and a nonlinear equalizer for receiving the signals preprocessed by said Linear Equalizer and for further processing said preprocessed signals and eliminating the echoes/channel taps of the induced ISI to be equalized by said nonlinear equalizer, thereby compensating for the entire ISI induced by said channel.

Enhanced equalization based on a combination of reduced complexity MLSE and linear equalizer for heavily ISI-induced signals

A method for performing blind channel estimation for an MLSE receiver in a communication channel, according to which Initial Metrics Determination Procedure (IMDP) is performed using joint channel and data estimation in a decision directed mode. This is done by generating a bank of initial metrics that assures convergence, based on initial coarse histograms estimation, representing the channel and selecting a first metrics set M from the predefined bank. Then an iterative decoding procedure is activated during which, a plurality of decision-directed adaptation learning loops are carried out to perform an iterative histograms estimation procedure for finely tuning the channel estimation. Data is decoded during each iteration, based on a previous estimation of the channel during the previous iteration. If convergence is achieved, ISI optimization that maximizes the amount of ISI that is compensated by the MLSE is performed.

Blind channel estimation method for an MLSE receiver in high speed optical communication channels

A method for estimating the phase of a modulated complex optical signal, according to which, the phase of the signal is isolated and the complex amplitude of the signal is digitized by a block of P samples. An adaptive filter minimizes phase-error between the phase of the received symbol and the phase of a sample, rotated by a phase correction factor, by iteratively performing a Block-Wise Phase LMS estimation on the samples using a step size parameter. During each iteration, the resulting correction factor consists of the sum of the estimated errors multiplied by this parameter, and the correction factor of previous iteration, which is updated, until obtaining the final correction factor from the last iteration. The samples constituting the received signal are recovered by adding the most updated correction factor to the phase of each sample and performing a decision regarding the phase of each sample.

Hardware efficient implementation of decision feedback phase estimation for an ultra high speed coherent receiver

The present invention is directed to a MIMO equalization system and method, optimized for baud rate clock recovery in coherent symbol-spaced DP-QPSK Metro systems. According to this method, the Mueller & Muller timing function is extended to cope with controlled ISI induced signals, while decoupling between MIMO equalization and clock recovery loops, using a midpoint output of the equalizer for timing estimation, instead of its final output. At least a portion of controlled Inter-Symbol Interference (ISI) is kept intact and the controlled ISI is compensated by an MLSE, right after carrier timing synchronization.

MIMO equalization optimized for baud rate clock recovery in coherent DP-QPSK metro systems

Method and system for optimally equalizing distortion of an optical data channel carrying coherent optical signals with a given analog bandwidth B. A receiving end with IQ paths receives signals and a balanced detector detects signals in each path. The bandwidth of the detected signals is reduced by a factor of N by filtering the output of each path using an AAF with a cutoff frequency optimized to the analog bandwidth 2B/N of each path, where the AAF has deterministic attributes and introducing Known ISI. The signal is sampled at the AAF output by an ADC, at a sampling rate of 2B/N. The samples of each path are post-processed by a digital processor operating at a data rate of 2B/N, where post-processing represents the compensation of the distortion and the input data stream is reconstructed by optimally decoding the output of the processor using a decoder, which compensates the ISI.

Method and system for coherent equalization of chromatic dispersion of optical signals in a fiber

System and method for digitally equalizing a data channel having wide channel impulse response for clock recovery of heavily ISI-induced received signals operating at one sample per symbol, according to which the received signal is pre-processed to provide a received signal with modified constellation, which is pre-processed for the decision process of signal with Inter-Symbol Interference by introducing controlled ISI to the received signal. The decision process is performed, based on a higher order vocabulary according to the introduced controlled ISI.

Digital baud rate clock recovery of heavily ISI-induced signals

System and method for equalizing a high bit rate optical communication channel in a symbol spaced adaptive Multiple-In-Multiple-Out (MIMO) system, where the optical communication channel carries a signal that is sampled at a symbol rate. Accordingly, Anti Aliasing Filtering (which introduces distortions in the form of Deterministic Inter Symbol Interference D-ISI) is applied in a MIMO channel, in order to reduce the aliasing effect associated with symbol rate sampling. The Polarization Mode Dispersions introduced in the optical communication channel are solely compensated by a MIMO Equalizer, which ignores the Deterministic ISI (D-ISI) distortion. Then the Deterministic ISI (D-ISI) distortion is solely compensated by an independent Deterministic Equalizer (DE).

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Kfar Bilu, Israel

Dan Sadot