Optical phase conjugation technique using four-wave mixing in semiconductor optical amplifier

A semiconductor-optical-amplifier-based technique to generate the conjugate of an optical signal is presented. The original probe signal and its conjugate appear at opposite ends of the semiconductor optical amplifier, improving, therefore, existing techniques. The basic concept was proposed many years ago but, to the best of our knowledge, has never been experimentally verified. An explanation is given as to why this was not possible, what modifications render the idea practical are explained and experimental results that prove its feasibility are shown.