Closed-Loop Resonant Fiber-Optic Gyroscope With a Broadband Light Source

The resonant fiber-optic gyroscope (RFOG) with a broadband light source has recently emerged as an attractive new type optical gyroscope. However, the use of a broadband source limits the linear dynamic range and worsens the scale factor accuracy. In this article, the closed-loop scheme of the broadband source-driven RFOG is proposed and demonstrated. First, a novel method called the period-stacking method is presented. Then the closed-loop mechanism of the broadband source system is revealed. Although the rotation-induced frequency difference is wavelength-dependent in the broadband source scheme, we are pleased to find that the frequency shift generated by the serrodyne modulation is wavelength-independent and can be used to compensate for the rotation information. Finally, a closed-loop broadband source-driven RFOG with a 100 m-long and 7.6 cm-diameter fiber-optic ring resonator is experimentally demonstrated. The measured result shows that the long-term bias stability of the closed-loop broadband source-driven RFOG is 0.0063 degrees/h over a test time of up to 500 minutes. The temperature dependence drops from 2.8 (degrees/h)/degrees C in the open-loop system to 0.54 (degrees/h)/degrees C. It is improved by a factor of 5.2. The open-loop linear detection range of +/- 50 degrees/s is improved to +/- 350 degrees/s. It is improved by a factor of 7. The open-loop scale factor nonlinearity of 8% is decreased to 0.0281% (281 ppm), which is improved by a factor of 285.