All-optical phase multiplexing from DPSK WDM signals to DQPSK using four-wave mixing in highly-nonlinear fiber

摘要

Thanks to the high spectral efficiency, improved dispersion tolerance, and reduced electronics bandwidth requirement, differential quadrature phase-shift keying (DQPSK) is regarded as an excellent candidate for long-haul transmission, whereas differential phase-shift keying (DPSK) can be employed in access and metro networks. Therefore, all-optical phase multiplexing from DPSK signals to DQPSK is desired to enable interfacing between access/metro networks and long-haul transport. In this paper, we propose and experimentally demonstrate all-optical phase multiplexing of two input 10-Gb/s π/2-shifted DPSK signals at different wavelengths to one spectrum-efficient 20-Gb/s DQPSK signal using four-wave mixing (FWM) in a highly-nonlinear fiber (HNLF).