Controlling Microring Resonator Extinction Ratio via Metal‐Halide Perovskite Nonlinearity

Abstract The exceptionally high optical nonlinearities, wide bandgap, and homogeneity in solution‐processed metal‐halide perovskite media are utilized as optical nonlinear elements on a silicon photonic platform for low‐power‐active components, such as all‐optical switches, modulators, and lasers. With room temperature back‐end‐of‐line compatible processing, a hybrid metal‐halide perovskite (CH₃NH₃PbI₃) microring resonator (MRR) structure is fabricated on a foundry‐processed low‐loss silicon photonic platform. With in‐plane excitation near the light intensity of 110 W m⁻², strong two‐photon absorption and free‐carrier absorption saturation are observed. With 10³ field enhancements by MRRs, the photorefractive effect in the metal‐halide perovskite reduces linear absorption, represented by 10² improvement of the MRR's intrinsic quality factor and 20 dB enhancement of the extinction ratio.