High‐Bandwidth and Large Dynamic Range Photonic Crystal Accelerometer Based on On‐Chip Integration

We report a monolithically integrated cavity optomechanical inertial accelerometer based on a waveguide‐coupled photonic crystal zipper cavity implemented on a lithium niobate thin‐film platform. By employing a fully integrated push‐pull design and replacing conventional fiber taper coupling with on‐chip waveguide coupling, the device achieves high optical stability, reduced low‐frequency noise, and enhanced photonic integration. Based on static tests, the accelerometer exhibits a displacement resolution of 6.9 fm Hz −1/2 , a noise‐equivalent acceleration of 9.25 µg Hz −1/2 , and a sensing bandwidth exceeding 15 kHz. Experimental characterization shows that the push–pull configuration effectively suppresses off‐axis crosstalk to below 0.022%. Electro‐optic modulation and electrostatic force feedback are co‐integrated on chip, enabling a dual‐loop closed feedback system that can significantly expand the dynamic range of the accelerometer and reduce its nonlinearity. Under our design specifications and test conditions, the dual‐loop closed feedback system expands the dynamic range to over 20 g. The non‐linearity is reduced from over 8.3% to 0.01%, with a 1 g acceleration input. This work demonstrates a scalable platform for high‐resolution, broadband, and low‐noise inertial sensing, with significant potential for advanced applications in navigation, stabilization, and motion detection.