40 Gbit/s, 16-ary (4 bit/symbol) optical modulation/demodulation scheme

Abstract

A practical 16-ary amplitude-phase-shift-keying (16APSK) optical modulation/demodulation scheme (4 bit/symbol) with a combination of multilevel amplitude and phase modulations is proposed, and its feasibility is successfully demonstrated for the first time. The spectral width of return-to-zero 16APSK signal is only 0.27 nm (33.75 GHz) at 20 dB down, even with 40 Gbit/s modulation.