British Telecommunications Public Limited Company

Roy Andrew Lobbett

David W Smith

David B Payne

Godfrey R Hill

Sandrew Robert John Cook

A gated optical amplifier for a PON includes an input for receiving an optical signal to be amplified, an output for outputting and amplified optical signal, an optical amplifier device for amplifying an optical input thereto, a detector, and an optical switch for allowing the amplified optical signal to leave the output upon the detector detecting the presence of an optical signal of a predetermined magnitude.

Optical network

Apparatus for converting a frequency division multiplex (fdm) signal to a time domain multiplex (tdm) signal in which a voltage control oscillator whose output is a staircase of reference frequencies is mixed by a mixer with a received fdm signal. Each received frequency is output in turn at a common intermediate frequency from a bandpass filter thereby forming a tdm signal after passing through a demodulator and low pass filter. The conversion may take place in the optical domain by mixing optical reference frequencies with an optical fdm signal in, for example, a coherent heterodyne optical receiver.

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Ipswich, United Kingdom

Roy Andrew Lobbett