Infinera Corporation

Pierre Mertz

Kuang-Tsan Wu

John Duncan McNicol

David F Welch

Stephen G Grubb

Han Henry Sun

Hai Xu

Jeffrey Thomas Rahn

David J Krause

Michael Francis Van Leeuwen

Mohamed Osman

Omer Faruk Yilmaz

Demin Yao

Steven William Beacall

Sumudu Geethika Edirisinghe

Robert Maher

Domanic Lavery

Adbullah Karar

Methods, systems, and apparatus, including computer programs encoded on computer storage media, for applying non-linearity to digital subcarriers. A receiver includes a detector circuit operable to receive a first optical signal over an optical link, the first optical signal carrying first data. The receiver includes a carrier recovery estimation circuit operable to generate compensated data by correcting errors in the first data. The receiver includes a non-linear coefficient estimation circuit operable to (i) receive the compensated data, and (ii) estimate one or more non-linear coefficients, wherein information indicative of the estimated non-linear coefficients is transmitted over an optical network, such that a second optical signal is transmitted based, at least in part, on the estimated non-linear coefficients, the second optical signal being received by the receiver.

Perturbative-based nonlinear compensation for digital subcarrier systems

A transceiver is herein described. The transceiver comprises an optical source providing an optical signal, a modulator receiving the optical signal and configured to encode data into the optical signal, a transmitter module to receive data to be encoded into the optical signal and having at least one drive circuit supplying driver signals to the modulator to cause the modulator to encode data into a carrier having a frequency band and a tone signal outside of the frequency band into the optical signal, a narrowband filter operable to receive a portion of the optical signal via an optical loopback, the optical signal having the encoded data and a first tone reflection of the tone signal at a first instant of time and to pass the first tone reflection, a polarimeter operable to receive the first tone reflection and determine a first tone polarization of the first tone reflection.

State of polarization sensitive coherent optical time domain reflectometry

Described herein is an apparatus including a continuous wave idler and an optical coupler that provide an optical signal having a power greater than optical channels carrying data, and positioned at a cross-over point between two spectral bands, with each band encompassing multiple optical channels.

Fast system optimization (FSO) with optimally placed recovery tones

A method and system are herein disclosed. A coherent optical receiver receives a first optical data carrier signal at a first instant of time and a second optical data carrier signal at a second instant of time, generates at least four first data streams from the first optical data carrier signal and at least four second data streams from the second optical data carrier signal; and circuitry calculates a first aggregate power of the first data streams and a second aggregate power of the second data streams; applies an adjustable temporal low pass filter to the first aggregate power and the second aggregate power resulting in a compensation power, the adjustable temporal low pass filter adjusted to achieve a performance metric; and phase-rotates the first data streams and the second data streams proportional to the compensation power.

Digital nonlinear phase compensator for legacy submarine cables

A method is described in which a loss of spectrum in an optical signal having an optical signal spectrum is detected. The optical signal is transmitted from a first node to a second node. In response to detecting the loss of spectrum in the optical signal, at least one idler carrier without data imposed is supplied into the optical signal spectrum transmitted from the first node to the second node, the optical signal spectrum encompassing a frequency band including a plurality of optical channels, the idler carrier being amplified stimulated emission light having a frequency corresponding to a first optical channel of the plurality of optical channels.

Systems and methods for dynamic spectral shaping in optical communications

The present disclosure allows for optical link capacity to be optimized based on transmission parameters, such as amplifier gain, link loss, optical signal-to-noise ratio. For example, optical signals at wavelengths that are susceptible to impairments, such as non-linear effects, or that are not adequately amplified by an optical amplifier, may be modulated in accordance with lower rate/less spectrally efficient modulation formats ('low rate formats') that are more noise tolerant. On the other hand, those optical signals at wavelengths that are less susceptible to or do not incur such impairments may be modulated in accordance with highly spectrally efficient/higher rate modulation formats ('high rate formats') that are more noise sensitive. Accordingly, a maximum or optimized capacity may be realized through appropriately choosing, for each channel, a particular modulation format and channel spacing. Such optimized capacity can be readily obtained with adaptive driver circuits.

Dual rate QPSK/TCM-QPSK optical modulation

A system receives four-bit symbols that correspond to traffic associated with a three-bit phase modulation scheme and are encoded based on a four-bit phase modulation scheme. The system determines values with which to perform equalization that enable the four-bit symbols to be restored to a condition that existed prior to being transmitted to the system. The system performs, using the values, equalization on a four-bit symbol that includes at least a first pair of bits associated with a first polarization, and performs, after completing the equalization, another equalization on another four-bit symbol that includes at least a second pair of bits associated with a second polarization. The system identifies a three-bit symbol, of a set of three-bit symbols associated with the three-bit phase modulation scheme, based on the equalized first pair of bits and the equalized second pair of bits, generates the three-bit symbol, and outputs the three-bit symbol.

Equalization mechanism for processing traffic based on three-quadrature amplitude modulation (3QAM)

An apparatus including a photodiode, a low pass filter, an analog-to-digital converter, an interpolation circuit and a digital signal processor is disclosed. The photodiode receives a portion of a plurality of optical signals, each of which is modulated in accordance with a corresponding one of a plurality of data streams, and each having a corresponding one of a plurality of wavelengths. The photodiode supplies an electrical output. The low-pass filter supplies a filtered output in response to the electrical output. The analog-to-digital converter is configured to sample the filtered output at a first sampling rate to generate a plurality of first data samples. The interpolation circuit is configured to receive the plurality of first data samples and supply a plurality of second data samples at a second sampling rate less the first sampling rate. The digital signal processor circuit is configured to receive the plurality of second data samples.

Upsampling optical transmitter

Systems and methods are disclosed including a subsea link idler apparatus comprising at least one data laser generating a first laser beam as a data signal, having a first frequency within a first data channel bandwidth slot; a first continuous wave laser generating a second laser beam with a first polarization and a second frequency being within a second data channel bandwidth slot; a second continuous wave laser generating a third laser beam with a second polarization different from the first polarization and a third frequency being offset from the second frequency and being within the second data channel bandwidth slot; a polarization beam combiner positioned in paths of the second and third laser beams combining the second and third laser beams into an idler signal; and a transmitter receiving and transmitting the data signal and idler signal.

Subsea optical communication system dual polarization idler

Consistent with the present disclosure, data, in digital form, is received by a transmit node of an optical communication system, and is then provided to a modulator that, in turn, modulates light, received from an optical source at one of a plurality of periodically and preferably minimally spaced wavelengths. The plurality of periodically spaced wavelengths or carriers are grouped together with minimal carrier spacing, to form a superchannel. The carrier spacing between adjacent carriers is determined by detecting a beat frequency of a combined optical signal that includes the outputs of two adjacent optical sources. The beat frequency corresponds to a frequency difference between the outputs of the adjacent carriers. This frequency difference should correspond to a desired carrier spacing between each of the plurality of carriers. A frequency error between the beat frequency and the desired carrier spacing is then measured by down-converting the beat frequency with respect to a target reference frequency corresponding to the desired carrier frequency spacing. Based on the determined frequency error, the optical sources are controlled to adjust in frequency to minimize or reduce the frequency error to zero. For every pair of adjacent carriers, the corresponding outputs of the optical sources are compared in the above manner to determine a plurality of frequency errors. Each optical source can thus be tuned in order to realize a precise carrier spacing between each of the adjacent carriers.

Apparatus to control carrier spacing in a multi-carrier optical transmitter

An optical system may have an optical transmitter including a digital signal processor to receive a signal channel, add data corresponding to a pilot tone, generate a digital signal associated with the signal channel and including the pilot tone, and output the digital signal. The optical system may further have a digital-to-analog converter to convert the digital signal to an analog signal, a laser to provide an optical signal, and a modulator to receive the optical signal and the analog signal, and modulate the optical signal based on the analog signal to form a modulated optical signal. The modulated optical signal may include the pilot tone. The optical system may also have an optical receiver to receive the modulated optical signal, process the modulated optical signal to determine a phase associated with the pilot tone, and apply the phase to the modulated optical signal to recover the signal channel.

Nonlinearity compensation using pilot tones

A compensator device may include a selection switch to receive a first optical signal and provide first and second groups of channels associated with the first optical signal; a polarization beam splitter to receive the first channels, and provide first and second components; a photodiode that provides an electrical signal indicative of an intensity of the first group of channels; a first modulator to receive the electrical signal and the first components and to modulate the first components to form first modulated channels; a second modulator to receive the electrical signal and the second components to modulate the second components to form second modulated channels; a polarization beam combiner to receive the first and second modulated channels to form combined modulated channels; and a coupler to receive the combined modulated channels and the second group of channels to form a second optical signal.

Nonlinear compensation in WDM systems

Consistent with the present disclosure, data, in digital form, is received by a transmit nodes of an optical communication, and converted to analog signal by a digital-to-analog converter (DAC) to drive a modulator. The modulator, in turn, modulates light at one of a plurality of wavelengths in accordance with the received data. The modulated light is then transmitted over an optical communication path to a receive node. At the receive node, the modulated optical signal, as well as other modulated optical signals are supplied to a photodetector circuit, which receives additional light at one of the optical signal wavelengths from a local oscillator laser. An analog-to-digital converter (ADC) is provided in the receive node to convert the electrical signals output from the photodetector into digital form. The output from the ADC is then filtered in the electrical domain, such that optical demultiplexing of individual channels is unnecessary.

Growing community of inventors

Baltimore, MD, United States of America

Pierre Mertz