Polarisation diversity is an important technique in coherent optical communications. The assembly of cost effective optical networks for realisation of this technique requires low-loss stable and practical polarisation maintaining coupler components. Fused fibre couplers produced from birefringent fibre in which the stressinducing regions have been index matched to the surrounding cladding offers a practical solution. Using this method low-loss polarisation maintaining 3 dB couplers and polarisation beam splitting couplers have been produced and assemblies formed to perform polarisation diversity.
Thomas John Cullen,
"Polarization-diversity fiber networks", Proc. SPIE 1372, Coherent Lightwave Communications: Fifth in a Series, (1 January 1991); doi: 10.1117/12.24918; https://doi.org/10.1117/12.24918