Nanomechanical Proximity Perturbation for Switching in Silicon-Based Directional Couplers for High-Density Photonic Integrated Circuits

We describe and demonstrate nanomechanical near-field proximity perturbation for tuning the effective refractive index of silicon-based high-density photonic integrated circuits. The proximity perturbation technique causes an antisymmetric refractive index change in a directional-coupler implementation, enabling switching action from the cross to the bar state. An almost 8-dB extinction ratio with ~14 × ¿s switching speeds is experimentally achieved using this technique with our single-mode waveguides of 500 nm × 200 nm cross section coupled to a movable 100-nm perturbing dielectric. A practical single-level switch with ring resonators fabricated by CMOS-compatible methods is also demonstrated.