Phase-locked dual-loop optical fiber gyroscope

Fiber-optic gyroscopes (FOGs) are widespread sensors used in different fields, such as inertial sensing, navigation, positioning systems, and seismology. In particular, for applications where high bandwidth and dynamic range are necessary, such as rotational seismology, FOGs are used in closed-loop configuration. Here, we show a novel closed-loop FOG based on a dual feedback configuration. Optical phase is controlled by serrodyne modulation via an electro-optic modulator, while electronic phase is stabilized via a digital phase-locked loop (PLL) system. System performance demonstrates that this approach enables both wide dynamic ranges, gaining up to four orders of magnitude at low frequency, and a high bandwidth.