A novel non-uniform spacing coherent heterodyne WDM system with high channel efficiency

A novel non-uniform spacing coherent heterodyne wavelength division multiplexing (WDM) system is proposed, analyzed and investigated in this paper. High channel efficiency is realized by reducing the average channel space to half the value of the traditional uniform spacing WDM systems. Simulation shows that the proposed scheme exhibits excellent laser line width toleration of 10 MHz and channel space deviation toleration of ± $40%. Experiment setup of 2.5 Gbit/s heterodyne WDM transmission including differential phase shift keying (DPSK) and non-return-to-zero (NRZ) channels is established to investigate the scheme.