REVIEW OF SEMICONDUCTOR OPTICAL AMPLIFIER (SOA) FUNCTIONALITIES

The Semiconductor Optical Amplifier (SOA) is a photonic device which is increasingly being utilized in many modern state-of-the-art optical communication networks. The SOA provides numerous highly efficient and cost-effective solutions to many network problems, and therefore generates great new interest for a wide variety of applications in future all optical communication systems. SOA based subsystems have been proven to have the capability of implementing the SOA into many practical applications and functions. In this paper, the functionalities of the SOA, based on linear and non-linear responses, are reviewed. The basic applications of SOAs in optical communication systems are also discussed: as post-amplifier (or booster amplifier), in-line amplifier and as preamplifier. In addition, various wavelength conversion schemes based on the inherent nonlinearities of the SOA are reviewed: cross gain modulation (XGM), cross phase modulation (XPM) and four-wave mixing (FWM). Besides wavelength conversion and amplification, SOAs can also be used for future applications such as optical switching, gating and “spectrum-sliced” systems; and these are also reviewed.