Rotational Seismometer Based on Dual-Polarization Fiber-Optic Angular Accelerometer

Seismic waves induce rotational motion in the medium as they propagate. The signal characteristics of rotational motion contain information about the anisotropy of the shaking, thereby enabling a more comprehensive study of the seismic source and its wave field. To achieve the detection of low-frequency signals within seismic wave signals, we propose a rotational seismometer based on a dual-polarization fiber-optic angular accelerometer. The rotational seismometer achieves high-sensitivity detection of seismic waves through sensing angular acceleration, with a sensitivity of 4.8 × 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-9</sup> r/s<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>/√Hz. Within a bandwidth range of 0.002 - 100 Hz, the rotational seismometer exhibits a flat frequency response. Experimental results from artificial seismic sources demonstrate that the proposed seismometer shows excellent seismic signal detection capabilities across the entire frequency range. This research provides theoretical and technical support for the development of new high-sensitivity seismometers, thereby advancing the field of rotational seismology.