Research on Broadening Frequency Band and Improving Sensitivity of Lower Cross-Talk F-P Cavity Geophone

A method to broaden frequency bandwidth and enhance the sensitivity of a Fabry-Pérot (F-P) geophone is proposed, and the corresponding high-performance geophone is designed and demonstrated experimentally. The theoretical model of F-P geophone based on wavelength demodulation is established, and while this model effectively enhances sensitivity, extends the frequency bandwidth under the determined higher resonance frequency, and suppresses cross-sensitivity. Following this design idea, we have cleverly designed and fabricated a F-P cavity geophone filled with a sensitizing medium. Experimental results show that the geophone has a resonant frequency of 1311.7 Hz and a sensitivity ranging from 1.35 nm/G to 2.59 nm/G within the frequency bandwidth. Compared to air-filled media, the operating band is widened by 270 Hz, and the sensitivity is increased by a factor of 1.07 to 1.33. Additionally, the cross-sensitivity is maintained below 4.9%. These results indicate that the geophone exhibits excellent response characteristics. And this design concept and method hold significant potential for practical applications. Therefore, the F-P geophone with these characteristics is a promising candidate device in the field of vibration detection.