Optical–mechanical collaborative sensitivity enhancement for extrinsic fiber-optic Fabry–Perot accelerometers

We propose what we believe is a novel sensitivity-enhancement method for extrinsic Fabry-Perot accelerometers (EFPAs) based on a wavelength-division multiplexing (WDM) cascading scheme. The core mechanism relies on an opto-mechanical coupling (OMC) technology, in which an integrated filter-collimator forms a cascaded dual-interferometer cavity structure. Under vibration, the two reflective surfaces move in opposite directions, inducing a push-pull spectral shift in the two cavities simultaneously. This configuration amplifies the optical response through two synergistic effects: effective cavity length extension and increased spectral spacing, thereby significantly enhancing sensitivity. Meanwhile, the dual Fabry-Perot cavity configuration enables common-mode noise suppression. Experimental results demonstrate that, without sacrificing the operational bandwidth, the proposed OMC-based accelerometer achieves fourfold improvement in sensitivity compared to conventional EFPAs, reaching a maximum sensitivity of 29.38 nm/g at 460 Hz, with a low noise level of 8.3 pm.