Monolithic demodulator for 40-gb/s DQPSK using a star coupler

A novel device that demodulates both quadratures of the optical differential quadrature phase-shift keying (DQPSK) format in a single interferometer by using a 4 /spl times/ 4 star coupler was demonstrated. Simultaneous measurements of both DQPSK quadratures at 42.7 Gb/s are also presented.

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