High-sensitivity on-chip accelerometer based on a coupling-modulation whispering gallery mode microcavity

High-quality factor whispering-gallery-mode (WGM) optical microcavities offer a promising platform for high-performance accelerometers. However, most existing WGM accelerometers rely on off-chip microcavities with taper-fiber or prism coupling, which limit them with large footprints, poor stability, and limited scalability. To address these limitations, we propose a novel on-chip accelerometer based on a coupling-modulation WGM microring resonator, fabricated on the standard SOI platform. External acceleration excites integrated cantilever beam vibration, inducing a Mach-Zehnder interferometer (MZI) phase shift that modulates the coupling condition and translates directly into intensity variations at the output port. This mechanism provides precise and stable control of the spectral response, overcoming the inherent instability of conventional physical-gap modulation. The simulation-optimized device achieves a noise-equivalent acceleration of 10 <i>n</i><i>g</i>/Hz within a 10.5 mm × 1 mm footprint. Its CMOS-compatible monolithic architecture ensures robustness, scalability, and strong potential for large-scale integrated optical sensing applications.