Ciena Corporation

Nortel Networks Corporation

Northern Telecom Limited

Rockstar Consortium US LP

Bookham Technology Limited

Maurice M O'Sullivan

Kim Bryon Roberts

Michael Andrew Reimer

Shahab Oveis Gharan

Qunbi Zhuge

Andrew D Shiner

Leo L Strawczynski

John Duncan McNicol

Rongqing Hui

Kieran Parsons

Han Henry Sun

Kim Byron Roberts

Alan Robinson

Kuang Tsan Wu

Hamid Ebrahimzad

David W Boertjes

Amir Keyvan Khandani

Richard E Epworth

Douglas McGhan

Kevin Stuart Farley

Adrien Comeau

Giuseppe Bordogna

Ahmed M Awadalla

Andrzej Borowiec

Mohammad Ebrahim Mousa Pasandi

Chandra Sekhar Bontu

Roland A Smith

James St Harley

David Casson Bownass

Jonathan Paul King

Xuefeng Tang

James E Whiteaway

Robert William Keys

Mahmoud Taherzadehboroujeni

Wolfgang W Oberhammer

Howard Martin Sandler

Ian B Betty

Andrew Niall Robinson

Douglas James Beckett

Hanan Anis

David V Plant

Nigel Edward Jolley

David R Doucet

Jamie Gaudette

Manoj Verghese

Christopher R Fludger

Ross Alexander Saunders

Michael Hubbard

Roger Carroll

Joanne Wakefield

Yves Beaulieu

Richard D Habel

Kevan Jones

Jin Hong

Douglas W Charlton

Paul Warren

Riyaz R Jamal

Richard R Habel

Francisco Javier Vaquero-Caballero

Jin J Hong

Nourhan Eid

Dietmar Garthe

Xueyang Li

Zhenping Xing

Dave Walker

Seb Savory

David Ives

Fiona Davies

Les C Chan

A transmitter generates a first electrical signal comprising a first low-frequency signal, an empty period, and a pump pulse having a first frequency; and a second electrical signal comprising a second low-frequency signal and at least two probe pulses, each probe pulse having a second frequency that differs from the first frequency. The transmitter modulates first and second optical subcarriers having different polarizations using the first and second electrical signals, respectively. The transmitter generates an optical signal from the first and second optical subcarriers, wherein the first and second low-frequency signals overlap in time, wherein the empty period overlaps in time with one of the probe pulses, and wherein the pump pulse overlaps in time with another one of the probe pulses. The optical signal is detected at a receiver over an optical link, and the receiver uses the optical signal to estimate nonlinear phase shift in the optical link.

Estimating nonlinear phase shift in a multi-span fiber-optic link using a coherent receiver

An asymmetric coherent receiver includes an optical front end configured to split a received optical signal into two paths, wherein the split received optical signal experiences a different optical transfer function in one of the two paths; two photodetectors each configured to detect power one of the split received optical signals in each of the two paths to obtain corresponding electrical signals; and circuitry configured to perform electrical domain extraction of information of each of the corresponding electrical signals from the two paths, wherein the different optical transfer function provides additional information utilized in optical field reconstruction via direct detection.

Asymmetric direct detection of optical signals

A communication system is configured to generate a perturbed signal by perturbing an amplitude of a spectrum of an original signal in one or more spectral regions, and to propagate the perturbed signal through components of the communication system. The communication system is further configured to obtain a measurement of the perturbed signal in a first spectral region of the one or more spectral regions following the propagation of the perturbed signal, and to calculate an estimate of an impairment associated with the communication system based on the measurement.

Estimation of communication system impairments using spectrally selective signal perturbations

A system configured to perform a method for estimating external noise in a communication channel between a transmitter and a receiver is described. The method comprises obtaining a measurement of effective noise on decoded symbols at the receiver, the decoded symbols comprising noisy versions of symbols conveyed by a communication signal transmitted over the communication channel. The method further comprises storing a representation of a relationship between the effective noise, external noise in the communication channel, and one or more variable parameters. The method further comprises storing applicable values of the variable parameters, wherein each applicable value is associated with current properties of the transmitter or current properties of the receiver or both. The method further comprises calculating an estimate of the external noise in the communication channel using the effective noise, the applicable values of the variable parameters, and the representation of the relationship.

Estimation of external noise in a communication channel

A transmitter () applies a dimensional transformation to preliminary digital drive signals representing symbols, thereby generating transformed digital drive signals () designed to represent each symbol using a plurality of first dimensions of an optical carrier (), the first dimensions distributed over two or more timeslots. The preliminary digital drive signals are designed to represent each symbol using a plurality of second dimensions of the carrier, which differ from the first dimensions. Using the transformed signals, the transmitter generates () an optical signal (). A receiver () receives () an optical signal () and determines received digital signals () corresponding to the first dimensions. The receiver applies an inverse dimensional transformation to the received digital signals to generate preliminary digital drive signal estimates () corresponding to the second dimensions, thereby permitting estimation of the symbols (). The inverse dimensional transformation may average signal degradations in the received digital signals.

Dimensional transformation in optical communication

A monitorable hollow core (HC) optical fiber comprises one or more hollow core anti-resonant fiber (HC-ARF) segments and one or more monitoring segments alternatingly connected with the HC-ARF segments, and where each monitoring segment comprises one or more non-HC-ARF constituents. A method for monitoring a monitorable HC optical fiber comprises transmitting one or more first optical signals on the monitorable HC optical fiber, detecting one or more second optical signals on the monitorable HC optical fiber, and monitoring one or more optical properties of the monitorable HC optical fiber using the first optical signals and the second optical signals, where the monitoring is enabled as a result of interactions between the first optical signals and the non-HC-ARF constituents of the monitoring segments.

Monitorable hollow core optical fiber

An optical transmitter () is operable to generate an optical signal () by modulating a number N of frequency divisional multiplexing (FDM) subcarriers using transformed digital signals which are determined by applying a pseudo FDM (pFDM) transformation to preliminary digital signals representative of multi-bit symbols. Rather than experiencing the effects of the number N of FDM channels, the optical signal experiences the effects of a different number M of pFDM channels, where M&#x2260;N. In some examples, the number M of pFDM channels is less than the number N of FDM channels, and frequency-dependent degradations may be averaged across different symbol streams. In other examples, the number M of pFDM channels is greater than the number N of FDM channels, and different symbol streams may experience different frequency-dependent degradations. An optical receiver () is operable to apply an inverse pFDM transformation to recover estimates of the multi-bit symbols.

Pseudo frequency division multiplexing

Systems and method include a detector communicatively coupled to a fiber span; and processing circuitry connected to the detector and configured to digitally sample and process an output of the detector, detect phase changes in the output, and identify an electrostrictive response of the fiber span based on the detected phase changes and based on a dependence of the detected phase changes with frequency. A property of the fiber span can be determined on the electrostrictive response. The property of the optical fiber can include one or more of optical fiber material type, optical fiber material property, optical fiber area, optical fiber geometry, optical fiber condition, optical fiber stress and strain, optical fiber temperature. and optical fiber radiation exposure.

Methods and assemblies for using electrostriction to characterize properties of optical fiber

A digital instruction is generated regarding one or more electrical-to-optical conversion impairments induced at the transmitter of an optical communication system. The digital instruction may be used by the transmitter to reduce the impairments. Alternatively, or additionally, the digital instruction may be used by the receiver of the optical communication system to compensate for the impairments.

Mitigation of electrical-to-optical conversion impairments induced at transmitter

Generation of data streams for two dimensions comprises compensation for a nonideal response of a signal path in an optical communications signal. The data streams are converted to analog electrical signals which drive two dimensions of an electrical-to-optical converter. Output of the electrical-to-optical converter is coupled through an optical link to an optical-to-electrical converter.

Compensation of transmitter or receiver defects in an optical communications system

Systems and methods for estimating a transmit symbol sequence implemented in a coherent receiver include receiving a nominally error-free information bit sequence subsequent to Forward Error Correction (FEC) decoding; determining a nominally error-free estimate of the transmitted bit sequence based on the nominally error-free information bit sequence; and determining a nominally error-free estimate of the transmit symbol sequence by mapping the transmit bit sequence to transmit symbols. The system and methods can further include comparing a transmit optical field based on the transmit symbols to a received optical field for one or more measurements.

Systems and methods for error-free reconstruction of transmitted symbols in a coherent receiver

Methods and assemblies for determining a property or environment of an optical fiber, including: measuring a frequency dependent electrostrictive response of an optical fiber; and based on the measured frequency dependent electrostrictive response, determining a property of the optical fiber. The property or environment of the optical fiber includes one or more of optical fiber type, optical fiber material type, optical fiber material property, optical fiber area, optical fiber geometry, optical fiber condition, optical fiber stress and strain, optical fiber environment, optical fiber temperature, optical fiber routing, optical fiber spooling, and optical fiber radiation exposure.

Multiple receivers are comprised in a flexible coherent transceiver of a multi-span optical fiber network. Each of the multiple receivers is operative to handle communications on a respective channel. The multiple receivers measure optical characteristics. For each of the multiple receivers, the optical characteristics include optical nonlinear interactions on the respective channel, the optical nonlinear interactions being at least partially dependent from one span to another span. An optical power of a signal on each of the multiple channels is adjusted as a function of the optical characteristics.

Power control in an optical fiber network

An optical transmitter is operable to generate an optical signal by modulating a number N of frequency divisional multiplexing (FDM) subcarriers using transformed digital signals which are determined by applying a pseudo FDM (pFDM) transformation to preliminary digital signals representative of multi-bit symbols. Rather than experiencing the effects of the number N of FDM channels, the optical signal experiences the effects of a different number M of pFDM channels, where M&#x2260;N. In some examples, the number M of pFDM channels is less than the number N of FDM channels, and frequency-dependent degradations may be averaged across different symbol streams. In other examples, the number M of pFDM channels is greater than the number N of FDM channels, and different symbol streams may experience different frequency-dependent degradations. An optical receiver is operable to apply an inverse pFDM transformation in order to recover estimates of the multi-bit symbols.

A receiver may receive an optical signal over an optical communications channel established between the receiver and a transmitter, the received optical signal comprising a degraded version of a modulated optical signal generated at the transmitter. The receiver may determine received digital signals corresponding to a plurality of first dimensions of the received optical signal, wherein the first dimensions correspond to dimensions of an optical carrier modulated at the transmitter to represent a multi-bit symbol, and wherein the first dimensions are distributed over two or more timeslots. The receiver may determine preliminary digital drive signal estimates using an inverse dimensional transformation and the received digital signals, the preliminary digital drive signal estimates corresponding to a plurality of second dimensions. The receiver may determine an estimate of the multi-bit symbol using the preliminary digital drive signal estimates. The inverse dimensional transformation may average signal degradations in the received digital signals.

Dimensional transformation

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Maurice M O'Sullivan