Quadrature demodulation with a synchronous difference for broadband source-driven resonant fiber-optic gyroscopes

Abstract

A broadband source-driven resonant fiber-optic gyroscope (RFOG) has recently been proposed as a means of achieving navigation-grade performance in a 100-meter-long fiber-optic ring resonator with a simple optical structure and signal processing. In this paper, a mathematical model of sinusoidal modulation and synchronous demodulation is developed to analyze the effect of relative intensity noise of the broadband light source on gyro performance so as to obtain the optimal modulation index and minimize the angular random walk. On this basis, a quadrature demodulation synchronous difference scheme is introduced for the broadband source-driven RFOG, which further improves the bias stability of the gyroscope by utilizing its common-mode rejection. Finally, an angle random walk of 0.0026∘/h1/2 and a bias instability of 0.0051°/h were demonstrated by using a fiber-optic ring resonator with a length of 109 m and a mean diameter of 7.6 cm.