Electro-optical correlation utilising a semiconductor laser amplifier for spread spectrum systems

The paper reports on the use of a semiconductor laser amplifier to execute correlation in the optical domain. A new unipolar code based on bipolar Golay codes has been developed for use with the correlator. A sensor network interrogated through a spread spectrum approach utilising the correlator and modified Golay codes is proposed allowing signal processing to be performed in the optical domain, maintaining low crosstalk and a high probe duty cycle (50%). The semiconductor laser amplifier also acts as a detection preamplifier and removes the need for a high speed detector. The operation of a three sensor ladder network has been simulated showing zero crosstalk when using an ideal semiconductor laser amplifier and crosstalk of less than 0.7% taking into account the gain saturation effect