Monolithic DQPSK Receiver in InP With Low Polarization Sensitivity

We present a monolithic differential quadrature phase-shift-keying (DQPSK) receiver in InP consisting of a 1times2 coupler, two different-length waveguides, a 2times4 coupler, and four photodetectors. We demonstrate a method to reduce the interferometer polarization sensitivity and show preliminary results of 43-Gb/s DQPSK reception.