Finesse-Enhanced Ring Resonator Coupled Mach–Zehnder Interferometer All-Optical Switches

In the all-optical switches using Mach–Zehnder interferometer side-coupled with a ring resonator, the switching power is quadratically reversely proportional to the resonator finesse in the high-finesse case. In order to enhance the resonator finesse, the loss rate a and the coupler reflectivity r should approach 1. Therefore, we propose a new configuration by inserting an amplifier into the ring to compensate for the losses in the ring and using a pumped nonlinear coupler instead of the ordinary coupler. The resonator finesse can be enhanced dramatically and the minimum switching power can be obtained.