Phase-tunable polarization division multiplexing DPSK receiver using a single demodulator

We report a new design of differential phase-shift keying (DPSK) receivers which utilize a single demodulator to receive polarization division multiplexed signals. More than 20 dB extinction-ratio can be achieved by optimizing the phase detuning with a polarization controller in the receiver. Experimental demonstrations using 20 Gb/s polarization multiplexed DPSK signals and 2¹⁵-1 pseudorandom binary sequence are conducted to show the performance of the proposed receiver. After 60 km of optical fiber transmission, the receiver has less than 3 dB power penalty at bit-error rate (BER) of 10⁻⁹.