One-chip integrated polarisation-multiplexed DQPSK demodulator using silica-based planar lightwave circuit technology

A compact polarisation-multiplexed differential quadrature phase-shift keying (DQPSK) demodulator achieved by integrating a polarisation beam splitter and two DQPSK demodulators consisting of a delay interferometer and a 90°-hybrid using silica-based planar lightwave circuit technology is demonstrated. The optical characteristics of the fabricated demodulator were sufficient for the direct detection of 100 Gbit/s polarisation-multiplexed DQPSK signals.