A non-intrinsic Fabry-Perot（ F-P） cavity optical fiber sensor of quartz diaphragm is researched and fabricated for ultrasonic detection of strong magnetic field and high voltage environment and the ultrasonic signal is measured. The finite element simulation of the diaphragms of different materials is carried out by ANSYS. The relationship between the sensitivity

the response frequency and the diaphragm radius is obtained

and suitable fiber sensor is developed. Through the design of the demodulation system

use quartz material diaphragm sensor to test the frequency of ultrasonic signals

and the measured signal is comparied with piezoelectric sensor measured signal and analyzed. The simulation results show that the natural frequency and sensitivity of the quartz glass material are moderate compared with the different materials under the same radius and thickness

and the ultrasonic frequency of the piezoelectric sensor is 33 k Hz. The frequency of the F-P cavity fiber sensor is31. 3 k Hz

data measured by two sensors are similar. Experiments show that the quartz material is suitable as a diaphragm material for non-intrinsic F-P cavity fiber-optic sensors.