Ultra-Low-Frequency Tri-Component Fiber Optic Interferometric Accelerometer

We demonstrate a high-performance ultra-low-frequency tri-component fiber optic interferometric accelerometer (FOIA), designed particularly for application in seismic observation of ocean-floor deployment, with high sensitivity, low noise level, and large dynamic range. Experimental results show that the sensitivity of the FOIA is 57 dB re rad/g, and the noise levels of the three orthogonal components are 0.163, 0.181, and <tex-math notation="LaTeX">0.153~ μ g </tex-math> , respectively, within the operating frequency band (0.005–50 Hz). The dynamic range of the system is higher than 117.03 dB. Actual observational results of an M4.3 seismic event show that the prototypical system can clearly record the seismic wave, with unambiguous demarcation of S-wave and P-wave, and locate the hypocenter of the earthquake.