The self-switching mechanism in a Sagnac interferometer is studied numerically. A new structure of a semiconductor-optical-amplifier (SOA)-based Sagnac interferometer self-switch (SISS) is presented. For analyzing the switching characteristics of the structure, an improved finite-difference beam propagation method is utilized to study counterpropagation pulses in the SOA. All intraband nonlinear gain compression effects in the SOA that have not been considered simultaneously in previous Sagnac switches are considered. The effects of structural and input pulse parameters on the SISS operation are analyzed. Simulation results determine the optimum condition for the maximum switching output power.
