Dual polarisation optical hybrid using silica-based planar lightwave circuit technology for digital coherent receiver

Described is a compact dual polarisation optical hybrid (DPOH) that has been achieved by integrating polarisation beam splitters and 90°-hybrids fabricated with silica-based planar lightwave circuit technology. The fabricated DPOH worked completely passively without any adjustments and its optical characteristics were sufficient for the coherent detection of 111 Gbit/s DPQPSK signals.