Demonstration of flexible optical time-division multiplexing system for high-speed free-space optical communications

A high-speed free-space optical communication scheme based on optical time-division multiplexing (OTDM) is experimentally demonstrated. By multiplexing eight 2.5Gb/s base-rate signals, which is generated from a repetition-tunable actively mode-locked fiber ring laser modulated by pseudo-random binary sequence data stream, a 20Gb/s OTDM packet is obtained. After 50 m high-speed FSO system transmission, the 20Gb/s OTDM packet is injected into a highly nonlinear fiber (HNLF) loop to realize polarization-insensitive de-multiplexing based on four-wave mixing (FWM). Experimental results show that the OTDM de-multiplexer bit error rate (BER) can achieve 10−9 level with steady operation over 24 h, proving the practicality of this system. © 2016, The Optical Society of India.