Experimental Demonstration of RZ-8-APSK Generation Through Optical Amplitude and Phase Multiplexing

In this letter, we propose and experimentally demonstrate an optical amplitude and phase multiplexing scheme to generate a multilevel modulation format signal, return-to-zero eight-amplitude and phase-shifted keying (RZ-8-APSK). The proposed optical amplitude and phase multiplexing is mainly based on four-wave mixing (FWM) in highly nonlinear fiber. Cross-absorption modulation in an electroabsorption modulator is employed to intentionally adjust the extinction ratio of the generated RZ-8-APSK signal. Amplitude and phase information carried in the inputs is multiplexed and transparently transferred to the generated FWM components. In the experiment, 30-Gb/s RZ-8-APSK signals are generated from input 10-Gb/s on-off keying and 20-Gb/s RZ differential quadrature phase-shifted keying in an all-optical manner.