A Review on Adjustable Gain Clamping in Semiconductor Optical Amplifier

Abstract

Semiconductor optical amplifiers (SOAs) are a research curiosity in wavelength division multiplexed (WDM) based all-optical networks as they exhibit huge potential in high speed optical switching and gating applications andcan provide, in addition, broadband amplification of signals. However, their use in WDM systems has been severely hampered due to the effect of gain saturation occurring in conventional SOAs which ultimately results in inter channel crosstalk. Moreover, ultra-fast gain dynamics of SOA along with gain saturationtogether lead to signal distortions even in single-channel transmission. Therefore, for proper operation, the amplifier must provide constant gain with respect to input power variations. Also, to improve the applicability of SOAs in switched environment, there must be a provision for varying the clamped gain. Thus, in this paper, various gain clamping and adjustable gain clamping techniques which have been proposed and perceived till date have been reviewed. Also, the findings of the various papers are tabulated therein.