Synchronization and clock recovery in a ferroelectric liquid crystal spatial light modulator based free-space optical communication link.

Synchronization of the transmitter and receiver is crucial in a free-space optical communication system for the proper transfer and retrieval of user information. In this work, we propose a method for the synchronization and recovery of the clock signal at the receiver from the optical signal modulated by a ferroelectric liquid crystal spatial light modulator (FLCSLM) in the transmitter. We have demonstrated our scheme by building an experimental arrangement that comprises an FLCSLM based computer generated holography assembly for modulating the laser beam in the transmitter and a photodiode cum micro-controller circuit in the receiver to generate the synchronized clock. We present the experimental results to demonstrate the accuracy of the recovered clock and the successful retrieval of the transmitted user information. The scheme can work for amplitude modulated, phase modulated, or complex amplitude modulated information transfer based on the FLCSLM.