A direct detection method for DPSK/DQPSK signals

In this letter, a kind of receiver based on optical Bessel filter for DPSK/DQPSK signals direct detection is discussed. By using this receiver, good spectrums and back-to-back eye-diagrams for CSRZ-DPSK and CSRZ-DQPSK can be achieved respectively in simulation. Compared the traditional balanced receiver, it is simple, effective, and low costive for DPSK/DQPSK signals detection.