British Telecommunications Public Limited Company

Hitachi, Ltd.

British Telecommunications Corporation

Peter E Barnsley

Hideaki Tsushima

Alan McGuire

Michael J Robertson

Moshe Tur

Mohammed Shabeer

Howard John Wickes

David Kennedy Hunter

Peter Jonathon Legg

Reduction of interferometer noise in an optical network

A wavelength division multiplex communication system comprises a head station (2) and a plurality of terminal stations (1) interconnected by an optical fibre cable (3). The head station (2) transmits continuous wave modulated wavelengths (.lambda..sub.1 -.lambda..sub.k), and a signalling wavelength (.lambda..sub.0) which is used to indicate, in each time slot, which wavelengths in the following time slot are available for transmission. Each terminal station (1) is arranged to receive the signalling wavelength, to determine therefrom whether the next time slot contains any data packets for that terminal station and, if so, to receive the packets. The terminal station (1) is arranged, if it has a data packet to transmit, to determine from the signalling wavelength whether the next time slot already contains data packets for the destination station and, if so, to avoid data collision by not transmitting its own data packet. The terminal station (1) then determines a free wavelength (.lambda..sub.q) from the signalling wavelength (.lambda..sub.0), modulates the free wavelength with the data packet it is to transmit, and modifies the signalling wavelength.

WDM network with control wavelength

Optical clock extraction

A wavelength division multiplex communications system has a head station and a plurality of terminal stations interconnected by an optical fiber cable. The head station transmits CW modulated wavelengths (.lambda.-.sub.1 -.lambda..sub.k), and a signalling wavelength (.lambda..sub.0) which is used to indicate, in each time slot, which wavelengths in the following time slot are available for transmission. Each terminal station is arranged to receive the signalling wavelength (.lambda..sub.0), to determine therefrom whether the next time slot contains any data packets for that terminal station and, if so, to receive the packets. Each terminal station is arranged, if it has a data packet to transmit, to determine from the signalling wavelength (.lambda..sub.0) whether the next time slot already contains data packets for the destination station and, if so, to avoid data collision by not transmitting its own data packet. The terminal station then determines a free wavelength (.lambda..sub.t) from the signalling wavelength (.lambda..sub.0), modulates the free wavelength with the data packet it is to transmit, and modifies the signalling wavelength.

Wavelength division optical signalling network apparatus and method

Optical processing system

Optical clock recovery

Growing community of inventors

Suffolk, United Kingdom

Peter E Barnsley