Low-Frequency High-Resolution Fiber Fabry–Perot Interferometric Accelerometer Based on Double-Spring-Supported Oscillator

A compact optical fiber Fabry–Perot (FP) accelerometer was designed for microvibration measurements in the low-frequency band below 1 Hz. A double-spring-supported spring-mass oscillator was designed to increase the cross-axis suppression and reduce the structural stress, facilitating the low mechanical thermal noise of the accelerometer. The mechanical thermal noise of the accelerometer was reduced to 0.069 ng/Hz1/2 with the quality factor of 121.8 and the fundamental frequency of 13.4 Hz. Moreover, by carefully adjusting the extrinsic FP interferometer formed between the cleaved fiber end face and the proof mass through the designed screw-in integration adaptor, the acceleration can be read out with high sensitivity, which is achieved as 2.104 (±0.046) V/mg experimentally. The self-noise of the accelerometer was demonstrated as low as 1 ng/Hz1/2 at 1 Hz and 11 ng/Hz1/2 at 0.1 Hz, respectively, which is the superior level for this frequency band in the existing fiber-optic accelerometers as far as we know. The proposed optical fiber FP accelerometer can satisfy the requirement of microturbulence detection in the fields of geophysics and aerospace.