All-Optical Signal Processing by Using SOA Nonlinearities: Prospects for the Evolution of Next Generation of Optical Networks

This article focuses on the realization of all-optical signal processing functions based on the nonlinearities of a semiconductor optical amplifier (SOA) by reviewing the recent and significant patents and publications related to these new developments and applications. One of the main contributions of this paper is to highlight the feasibility of experimental implementation of three logic gates: NAND, OR, and NOR optical gates by exploiting the nonlinear polarization rotation in a SOA structure without changing the setup configuration. Switching between each optical function is done by only adjusting the input optical power level. The experimental investigation is done in free space, allowing optimum control and preservation of the polarization state of the injected and collected signals.