Optimization of wide frequency range 6H-SiC MEMS chips for a fiber optic Fabry–Perot accelerometer

Vibration detection using sensors with both wide working frequency range, good sensitivity, and other good performances is a topic of great interest in fields such as inertial navigation, deep-sea fishing boat engines condition monitoring, seismic monitoring, attitude, and heading reference system, etc. This paper investigates two 6H-SIC MEMS diaphragms, one triangular and the other square, used in a fiber optic Fabry–Perot (FP) accelerometer in an experimental scenario. The triangular chip shows a wide working frequency range of 630 Hz–5300 Hz, a natural frequency of 44.3 kHz, and a mechanical sensitivity of 0.154 nm/g. An optimal structure of the square chip used in a probe such as a fiber optic FP accelerometer also shows a wide working frequency range of 120 Hz–2300 Hz; a good sensitivity of 31.5 mV/g, a resonance frequency of 7873 Hz, an accuracy of 0.96% F.S., a frequency measurement error of 1.15%, and an excellent linearity of 0.9995.