Development of a High-Performance Rotational Seismometer Based on the Dual-Channel Fiber Optic Gyroscope

Abstract

This paper presents the development of a high-performance three-component fiber optic rotation seismometer (FORS) named DC-Rot3C for rotational seismic observation. Its core sensing element is a novel dual-channel interferometric fiber optic gyroscope (IFOG), which differs from conventional minimum configuration. The IFOG in DC-Rot3C is composed of two sensing channels, which can effectively suppress self noise such as relative intensity noise. This paper provides a detailed demonstration and analysis of the optical configuration, demodulation technology, layout construction, and noise suppression mechanisms of the developed DC-Rot3C. Furthermore, the performance of DC-Rot3C is tested, and the experimental results show that, with an effective sensing area of only <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$246\,\,\mathrm{m^{2}}$</tex-math></inline-formula>, the self-noise remains flat from 0.001 Hz to 100 Hz, reaching a sensitivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$6.2\times 10^{-9}\;\mathrm{rad/s/\sqrt{Hz}}$</tex-math></inline-formula>. Additionally, the angle random walk (ARW) reaches <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$4.54\times 10^{-9}\;\mathrm{rad/\sqrt{s}}$</tex-math></inline-formula>, and the bias instability (BI) reaches <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$2.96\times 10^{-10}\;\mathrm{rad/s}$</tex-math></inline-formula>. Compared with other IFOGs and FORSs, the DC-Rot3C exhibits superior performance with the same sensing area, providing a high-precision tool for seismic observation.