Northern Telecom Limited

Sandra Davis

Alan Fielding

Terry Bricheno

Vernon Baker

Christopher Chew

An optical fibre amplifier in which a length of optically amplifying fibre is spliced between a pair of 2.times.2 tapered fused fibre couplers each constructed from a length of amplifier type profile fibre and a length of transmission type profile fibre. In each coupler, one of two constituent fibres has been pre-stretched so as to match the propagation constants of the two fibres within the coupling region of that coupler.

Optical fibre amplifier

In the manufacture of a wavelength multiplexing 2.times.2 tapered fused fiber coupler by progressive stretching, the birefringence of the coupler resulting from the progressive stretching is subsequently nulled-out by elastic twisting of the coupler. The progressive stretching is performed, under temperature conditions providing a profile in the coupling region of the coupler having the property that the coupling strength for one of the principal polarization planes of the coupler remains substantially constant during said elastic twisting.

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Ware, United Kingdom

Sandra Davis