Nortel Networks Corporation

Ciena Corporation

Ciena Luxembourg S.a.r.l.

Giuseppe Bordogna

Kim Bryon Roberts

Maurice M O'Sullivan

James St Harley

Alan Glen Solheim

Kim Byron Roberts

Richard A Habel

Maurice Stephen O'Sullivan

Nigel Baker

Duncan John Forbes

Ian Hardcastle

David John Danagher

Takis Hadjifotiou

Bipin Patel

David W Boertjes

David Casson Bownass

Vipul Bhatnagar

Douglas McGhan

Riyaz R Jamal

Maurice O'sullivan

David Boertjes

A method of adding a transceiver including a transmitter and a receiver to an optical network. The transceiver is controlled to enable the receiver while maintaining the transmitter in a disabled state. The receiver detects a presence of an optical signal at a first wavelength. If an optical signal at the first wavelength is not present, the transmitter is enabled. Responsive to detection that an optical signal at the first wavelength is present: a feature of the optical signal, and a match condition between the detected feature and a predetermined feature are detected. The transmitter is enabled responsive to detection of the match condition.

Method for detecting wavelength usage conflicts in an optical network

In an Optical Add-Drop Multiplexer, a drop section comprises a Wavelength Selective Switch (WSS) having at least one drop-port, the WSS being operative to couple a respective set of w (where w&#x3e;1) wavelength channels from a received Wavelength Division Multiplexed (WDM) signal to each drop port. A respective 1:s power splitter is associated with each drop port. Each power splitter supplies the respective set of channels received from its drop port to each one of a corresponding set of coherent receivers. Each coherent receiver operates to receive a selected one of the respective set of channels.

Coherent augmented optical add-drop multiplexer

A method and system enables measurement of polarization dependent loss (PDL) in an optical communications system including a plurality of cascaded optical components. An optical signal having a predetermined initial polarization state is launched into the optical communications system. A polarization state of the signal is detected at a selected detection point downstream of the launch point. The PDE is evaluated using the predetermined initial polarization state and the detected polarization state.

Measurement of polarization dependent loss in an optical transmission system

An add/drop multiplexer/demultiplexer (ADM) for switching, modulating and attenuating optical signals in a fiber optic network employing wavelength division multiplexing (WDM) is disclosed. The ADM is equipped an optical multiplexer for splitting an input WDM signal into individual optical signals, leading to respective 2.times.2 switches. Each switch has another input originating from a plurality of 'add lines', and selects one of its inputs to be dropped and the other to continue along a main signal path. The retained signals may be modulated and attenuated prior to being tapped and finally multiplexed together by a WDM multiplexer. The tapped signals are optoelectronically converted and fed back to a controller, preferably a digital signal processor running a software algorithm, which controls the switching, modulation and attenuation. This permits remote control of the ADM functions by encoding instructions for the controller into a low-frequency dither signal that is embedded within the individual optical signals. The ADM can accordingly be instructed to reroute traffic, dynamically equalize or otherwise change optical channel power levels, and add or remove dither, all in real time. A specific optical channel may be reserved for control purposes, allowing a network administrator to 'log in' to the ADM to override the controller software algorithm. Optionally, the optical signals can be tapped upon entry to the ADM. A bidirectional ADM can be constructed from two unidirectional ADMs, and may share the same controller. Also, a single, general multi-input multi-output switch can be used to provide an arbitrary mapping between individual input and output optical signals.

Optical add/drop multiplexer/demultiplexer

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Ottawa, Canada

Giuseppe Bordogna