Abstract:

The effect of channel-spacing on differential phase shift keying （DPSK） systematical performance was analyzed and optimized through VPItransmission maker simulation, aiming at the severe distortion of DPSK signal to narrow channel-spacing for its broad spectrum. It is found that the delay time of the DPSK Mach-Zehnder delay interferometer （MZDI）-demodulator will be less than 1-bit duration for the 40 Gbit/s dense wavelength-division multiplexing（DWDM) system with 50 GHz channel-spacing, and become shorter according to the narrower optical filter bandwidth. Furthermore, the system achieves the optimal transmission performance by matching the variation of the optical add-drop multiplexer (OADM) series, with a method of feedback controlling of the delay time according to the monitored transmission performance indications.

Key words: optical communication, modulation formats, differential phase shift keying, Mach-Zehnder delay interferometer, delay time, VPItransmissionMaker simulation