All-optical switching by counterpropagating operation in cascaded semiconductor optical amplifiers

We propose a simple, compact, integrative, flexible, power-efficient, and a ll-optical switch. The operation is based on self-induced gain modulation l eading to nonlinear transmittance with a threshold level dependent on input powers of the data and control signals counterpropagating in cascaded semi conductor optical amplifiers. We demonstrate numerically the all-optical sw itch with small-signal modulation, low-power consumption, high-output power , and high-output extinction ratio.