Large-Scale Polarization-Insensitive Silicon Photonic MEMS Switches

We report on 50 × 50 silicon photonic micro-electromechanical-system (MEMS) switches with reduced polarization dependence. The switches make use of two-level waveguide crossbars and MEMS-actuated adiabatic couplers. Simulations indicate that by eliminating all polarization-dependent elements (e.g., waveguide crossings), low polarization-dependent losses (<1 dB) can be realized. An experimental prototype switch was fabricated by bonding two silicon-on-insulator wafers. A polarization-dependent loss of 8.5 dB and a polarization-dependent delay of 44 ps were measured. The extinction ratios are greater than 40 dB for both polarizations. With improved fabrication, total on-chip loss <2 dB can potentially be achieved for both polarizations.