New polarization-insensitive direction scheme based on fibre polarisation scrambling

A novel fibre polarisation scrambler is described for a large class of receivers using polarisation-dependent components, such as gratings, liquid-crystal etalon filters and acousto-optic filters. This technique is wavelength independent, is transparent to the transmission format and simple to implement. Using this approach, the variation in the received power for an arbitrarily polarised signal passing through a fixed polariser was reduced from greater than 40 dB to 1.4 dB.