Northern Telecom Limited

Stc, Inc

Vernon Baker

Terry Bricheno

Alan Fielding

Sandra Davis

Christopher Chew

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.

Polarization insensitive wavelength multiplexing 2.times.2 fibre couplers

Polarization beam splitters/combiners or polarization insensitive beam splitters/combiners are manufactured from low or zero birefringence single mode optical fibre, rather than high birefringence fibre, by using a differential pulling technique to induce the appropriate amount of form birefringence, the fibres being stretched further than hitherto.

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Harlow, United Kingdom

Vernon Baker