Noise analysis of LWIR photodetector based on HgCdTe for free space optical receiver

In present paper we have reported low noise LWIR photodetector optical receiver used in intensity modulated (IM/DD) direct detection system for free space optical communication applications. The model is used to explore the different types of noises associated with the photodetector as well as of amplifier and biasing resisters. In dark current modeling of detector we have considered all possible recombination mechanisms e.g. fundamental recombination (band-to-band and Auger) and non-fundamental recombination (Shockley-Read-Hall and surface recombination) mechanisms. All the noise components of the receiver circuit have been analyzed theoretically. The present analysis leading to dark current of the photodetector is I_D ap 5times10^-7 A, dynamic resistance of the LWIR detector R_D ap 10⁷ Omega, and noise-equivalent-power of receiver circuit NEP ap 10^-14 W-Hz^1/2.