Polarisation-insensitive coherent lightwave system using wide-deviation FSK and data-induced polarisation switching

The authors present a technique wherein polarisation-insensitive heterodyne detection is achieved through data-induced polarisation switching. The polarisation switching is brought about by inserting a passive, birefringent optical device in the path of the transmitted FSK signal. The experimental results show that this technique suffers a power penalty of 3-4 dB when compared with a conventional FSK system with perfectly matched polarisations. This compares well with the expected penalty of 3 dB. This approach uses a single optical receiver and no additional receiver electronics, which could be a significant advantage for local area networks