Switchable high-Q and high-sensitivity nanoscale MIM waveguide-based biaxial optical accelerometer.

Nanoscale biaxial accelerometers based on metal-insulator-metal (MIM) waveguides offer high sensitivity and strong immunity to electromagnetic interference, making them attractive for next-generation inertial sensing. However, achieving multi-axis detection, device miniaturization, and high performance simultaneously remains challenging. In this work, we propose, to the best of our knowledge, a novel dual-axis optical accelerometer that integrates a circular-shaped ring resonant cavity (CSRRC) and a square-shaped ring resonant cavity (SSRRC) within a compact MIM structure. The design enables switchable sensing along orthogonal directions, achieving a high Q-factor of 68.81 along the x-axis and a sensitivity of 0.102 nm/g along the y-axis. Finite element simulations reveal the nonlinear influence of key structural parameters on device performance. The CSRRC enhances field confinement for x-axis sensing, while the SSRRC utilizes coupling with a movable proof mass to boost y-axis sensitivity. A composite configuration with orthogonally embedded resonators supports independent detection over a range of -20g to 20g, with improved sensitivity and transmission performance. This work provides a theoretical foundation for highly integrated, high-performance optical accelerometers with potential applications in industrial monitoring, UAV navigation, and biomedical devices.