Nortel Networks Corporation

Bookham Technology Limited

Oclaro Technology Limited

Oclaro Inc.

Lumentum Technology UK Limited

Barrie Flintham

Kevan Peter Jones

Andrew Cannon Carter

Adrian Perrin Janssen

Jonathan Stuart Drake

Simon P Parry

Alan Robinson

Michael A Scobey

Jonathan Paul King

Robert William Keys

Mark R Hinds

Nigel Edward Jolley

Rad Sommer

Colin Smith

Paul Johnson

Rance Morgan Fortenberry

Mark E Bray

James Regan

Ian Peter McClean

Stephen David Fourte

Roger D Griggs

Graeme A Henderson

Martin P Poettcker

Robert A Baker

Roger M Gibb

Stephen Gardner

Toby J Reid

Alan A Solheim

Jonathon Stuart Drake

Joseph Mun

Stephen Andrews

Methods and apparatus for use in coherent transmission and reception of optical data signals. An integrated optics block () for use in a coherent optical transmitter comprising: a beam splitter () configured to split an input light signal into first and second input light signals, to output the first input light signal for use in an optical transmitter chip and to output the second input light signal for use as a local oscillator signal; a polarization combiner () configured to combine first and second received modulated light signals to form an output; and a polarization rotator () configured to rotate the polarization of the second modulated light signal such that it is substantially orthogonal to the polarization of the first modulated light signal prior to combining.

Optical component

An assembly includes an etalon assembly for dynamically locking a frequency of an optical beam to a set frequency, the etalon assembly being external to a laser source assembly that outputs the optical beam. The etalon assembly includes an etalon that receives the optical beam and generates via interference effects a transmission beam, the etalon having a thermal tuning range greater than one half of a free spectral range of the etalon. The etalon assembly also includes an etalon heater mounted to the etalon such that the etalon heater is configured to adjust the temperature of the etalon. The assembly includes a controller configured to retrieve calibration data based on the set frequency, calculate a set temperature for the etalon using a thermal tuning algorithm and the calibration data, and control the etalon heater such that the etalon has a temperature equal to the calculated set temperature.

Thermal locker

A variable gain optical amplifier comprises an EDFA for amplifying optical signals at different wavelengths and a pump driverfor optically pumping the EDFA to provide optical gain. An input detectoris provided for monitoring the power Pof input signals to the EDFA, and an output detectoris provided for monitoring the power Pof output signals from the EDFA. A gain control arrangement is provided for supplying a drive signal to the pump driverto control the optical gain including a feed forward arrangementfor supplying a feed forward signal dependent on the monitored input power P, and a feed back arrangementfor supplying a feed back signal dependent on the monitored output power P. In order to ensure rapid gain control the feed back arrangement comprises an adaptive proportional-integral (PI or PID) controllerfor controlling the optical gain at a required gain set point in accordance with proportional and integral control coefficients Kand Kcorresponding to a required gain profile, at least one of which is dynamically variable in dependence on the monitored output power P, the output signal from the controllerand the feed forward signal being added in an adderto produce the drive signal for the pump driver

Variable gain optical amplifiers

An optical component for gain-flattening multiplexed passband signals amplified with optical pump power, comprises a launch port optical waveguide operative to communicate multiplexed passband signals in a passband wavelength range and optical pump power in a different wavelength range; a thin film demux filter oriented to receive combined multiplexed passband signals and optical pump power from the launch port optical waveguide, and operative to pass the multiplexed passband signals and to reflect the optical pump power; a bypass port optical waveguide operative and oriented to receive and carry optical pump power reflected by the demux filter; a gain-flattening filter positioned to receive from the thin film demux filter and operative to pass the multiplexed passband signals with a desired attenuation profile for gain-flattening; and an output port optical waveguide oriented to receive and operative to carry at least multiplexed passband signals passed by the gain-flattening filter. Also disclosed are optical amplifiers comprising such GFF components. Also disclosed are optical filters comprising an optical substrate, a thin film demux filter on a first surface of the optical substrate, and a gain-flattening filter on an opposite surface of the optical substrate, wherein the demux filter is operative to pass multiplexed passband signals in a passband wavelength range and to reflect optical pump power in a different wavelength range, and the gain-flattening filter is operative to pass the multiplexed passband signals and to provide a desired attenuation profile to the multiplexed passband signals.

Optical gain flattening components, optical chips and optical amplifiers and methods employing same

An amplifying module for an optical network has a fiber amplifier for amplifying a multiplexed optical stream having a plurality of wavelength channels. The fiber amplifier has a set point gain. The module has module control means for controlling the operating conditions of the fiber amplifier and supplying means for supplying to the module control means information representative of the channel loading condition. In response to the information, the module control means adjusts the operating conditions of the fiber amplifier such that the fiber amplifier gain does not exceed an acceptable deviation limit away from a set point gain.

Amplifier gain error

An optical amplifier comprises: at least first and second amplifier stages, each stage comprising a doped fiber and a pump source for providing pump light to the fiber. The input and output power of the amplifier is measured to enable automatic gain control. The input and output power is processed in order to derive target pump source levels for achieving a substantially constant gain, and the temporal response of the gain control loop is varied in dependence on the target pump source levels. The response time of the gain control loop is thus matched to the open loop gain of the amplifier, taking into account the combination and settings of the amplifier stages.

Optical amplifier gain control

An optical amplifier comprises a pumped doped fiber with a power measurement circuit for measuring the input and output power of the amplifier. Automatic gain control is implemented, and the calculation of output power for the AGC loop takes into consideration the temperature provided by a temperature measurement device. This enables a flatter gain response to be achieved over varying input power, which enables an increase in the dynamic range of the amplifier and thereby a possible increase in system capacity of a WDM system using the amplifier.

In a WDM optical transmission system employing optical amplifiers in its transmission path, a supervisory signal channel, used for monitoring and controlling the operation of the amplifiers and spectrally separated from the data transmission, may be multiplexed with the data. A construction of amplifier is disclosed which is capable of being upgraded with an upgrade of the transmission system to include additional data handling capacity, for instance data transmission in an additional waveband and/or in the opposite direction, without interruption of the pre-upgrade data transmission path through the amplifiers. This is accomplished by the use of channel dropping and insertion filters disposed so that the amplifying data transmission path extends via the drop/insertion channel of those filters.

Optical amplifiers

A construction of gain tilt exhibiting optical amplifier that incorporates a gain flattening filter also includes a neutral density filter the value of whose attenuation is adjustable after assembly of the components of the amplifier. This neutral density filter is constructed by the performance of a succession of localised re-fusion operations at a localised region of an optical fiber. By this means the attenuation is increased to a desired value that provides the amplifier with optimised gain flattening at some predetermined value of amplifier external gain.

Optical amplifier manufacture

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Totnes, United Kingdom

Barrie Flintham