Performance analysis of an all-optical half-subtracter based on XGM in SOA at 20 Gbps

Implementation of all-optical algebraic and arithmetic operations is fundamental for successful realization of complex all optical signal processing (AOSP) tasks. Over the past few years, a number of All-optical computing devices such as half-adder, full-adder etc. have evolved based on 2(nd) (X-(2)) order and 3(rd) (X-(3)) order non-linear effects. In this paper, design and performance analysis of an all-optical half-subtracter based on cross-gain modulation (XGM) in bulk type semiconductor optical amplifier (SOA) capable of operating at 20 Gbps have been performed. A co-propagating structure has been utilized for the design purposes, which nullifies requirement of additional assisting light sources. Extinction ratios ( ER) and quality factors (Q-Factor) of order of greater than 9.389 dB and 7.29, respectively have been achieved for half-subtracter outputs. Performance analysis has been performed by varying order and width (T-FWHM) of input gaussian data pulse trains. Gaussian return-to-zero (RZ) data pulses of 3(rd) order and width (T-FWHM) = 0.5 have been identified as optimum input pulses.