The tunable demodulator of DPSK based on reflection differential delay interference

A new scheme of demodulating DPSK signal is proposed based on structure of differential delay interference which is suitable for variable bit-rate and the tuning speed is faster than the existed demodulator. The demodulation of variable bit-rate NRZ-DPSK formats of 10Gb/s and 40Gb/s are demonstrated, the BER after demodulating is lower than 10^-9. It is proved that this demodulator can be used to demodulate 10Gb/s to tens Gb/s bit rate DPSK signal. The demodulator can realize one-, half-, or quarter-bit delays for DPSK signals. Compared to other DPSK demodulators, this demodulator is tunable and the tunable speed is faster.