Algorithmically calibrated optical switch with high-extinction-ratio and low-polarization-dependence on 3-μm-thick SOI platform

Crosstalk, calibration complexity, and polarization dependence obstacle the precision of optical networks such as microwave photonics beamforming networks (MPBNs). The optical switch presented in this work, boasting high tolerance and polarization insensitivity, utilizes multimode interferometers (MMIs), a thermo-optical phase shifter, and variable optical attenuators (VOAs) on the 3μm-thick silicon-on-insulator (SOI) platform. The switch exhibits extinction ratio (ER) exceeding 32.5 dB within 140 nm bandwidth, with maximum ER of 50 dB, accompanied by 0.4 dB loss, and features switching speed of 16 μs/21μs. In 10-layer networks, the VOA-assist golden-section algorithm enables optimal calibration within 170 iterations, serving as fundamental component for establishing precise optical networks.