Fiber-Optic MEMS Accelerometer Based on Push-Pull Michelson Interferometer Structure

We demonstrate a fiber-optic micro-electron-mechanical systems (MEMS) accelerometer based on a symmetric push-pull spring structure made by micromachining on a silicon substrate, which combines the advantages of high sensitivity, low self-noise, and large operation bandwidth compared with existing fiber-optic MEMS accelerometers. A balanced Michelson interferometer based on a 3×3 fiber coupler is employed as a displacement transduction system, and an improved elliptic fitting algorithm (EFA) is proposed for phase demodulation within this system, addressing the limitations of the traditional EFA under small-signal condition. Experimental results validate the theoretical design and finite-element analysis, demonstrating that the proposed sensor achieves an average sensitivity of 48.17 dB re rad/g within its operational bandwidth of 5–80 Hz and a resonant frequency of 139 Hz, both of which closely align with the simulated results. The sensor's transverse crosstalk is less than 1.53%. The results of the self-noise evaluation experiment verify that the proposed sensor attains a low average noise of 40 ng/Hz^1/2, proving that it has nano-g resolution in acceleration detection applications.