1.3- $\mu $ m Silicon Optical Switch Integrated With Germanium Photodiodes for Stable Operation

A carrier-injection-type silicon optical switch (OSW) monolithically integrated with germanium photodiodes (Ge-PDs) is proposed and operated at a wavelength of 1310 nm. The Ge-PDs used for monitoring photocurrent achieve stable switching control. A 4 × 4 silicon OSW, ideally a path-independent-loss type, was fabricated on a silicon-on-insulator substrate. Measured loss variations of all 16 paths were ~3 dB, and the switching response of the OSW was faster than 10 ns. Feedback control of injection current of the OSW was demonstrated. This result shows that the proposed closed-loop feedback control by monitoring photocurrents of Ge-PDs has the potential for stable operation of matrix OSWs.