4 ×4 InAlGaAs/InAlAs optical-switch fabric by cascading mach-zehnder interferometer-type optical switches with low-power and low-polarization- dependent operation

High-speed optical switches are essential devices to construct next-generation optical networks. We have studied 2 × 2 InAlGaAs/InAlAs hybrid-waveguide-type Mach-Zehnder interferometer-type optical switches and demonstrated low-polarization-dependent switching operation with crosstalks of less than -20 dB, injection currents of about 5 mA, and response times of about 3 ns. In this letter, our conventional 2 × 2 optical switch was extended to a 4 × 4 optical-switch fabric by a cascading approach. As a result, fundamental switching operation was confirmed with low power consumption and low polarization dependence.