A Simple and Compact Passive Resonant Fiber Optic Gyroscope by Using Non-Reciprocal Polarization Techniques

TL;DR

The paper addresses the challenge of achieving navigation-grade rotational sensing with a compact, low-noise, and low-complexity passive RFOG. It proposes a passive architecture that combines broadband white-light multibeam interferometry with a Non-Reciprocal Polarization-Dependent Phase Shifter (NRPPS) installed inside the resonator to create two true quadrature points at $\pi/2$ and $3\pi/2$, enabling maximum Sagnac sensitivity without modulation. Theoretical analysis shows that the coupling ratio $R$ and the NRPPS phase shifts critically determine sensitivity and linearity, and a transmission-type NRPPS biases the CW/CCW resonances to achieve passive operation. An additional NRPPS section can further extend the angular-range reach, mitigating trade-offs associated with longer fiber loops. Compared with an earlier passive 3×3 coupler design, the proposed NRPPS-RFOG promises ~5× sensitivity enhancement and ~2× range extension, supporting a practical path toward navigation-grade, compact, and cost-effective RFOGs for demanding applications.

Abstract

We present a novel passive resonant fiber-optic gyroscope (RFOG) design that achieves two true quadrature points at $π/2 $ and $3π/2$, enabling angular rotation measurement with maximum sensitivity. The use of a broadband light source, as demonstrated in previous studies, eliminates the need for precise frequency locking, while the resonant enhancement allows high sensitivity with significantly shorter fiber lengths. Building on this approach, the present work integrates a Non-Reciprocal Polarization Dependent Phase Shifter (NRPPS) into the broadband RFOG configuration, called NRPPS-RFOG, enabling truly passive operation without the need for active modulation-demodulation. Theoretical analysis demonstrates that the coupling ratio and NRPPS phase shift critically influence both sensitivity and linearity. An additional NRPPS section extends the measurable angular rotation range, addressing limitations arising from long fiber loops. The proposed design combines compactness, high performance, and low complexity, offering a practical path toward navigation grade RFOGs. These results highlight the potential of passive NRPPS-RFOGs for cost-effective, high-precision rotational sensing in demanding applications.

Figures (6)

• Figure 1: The design of the RFOG using ultra-simple white-light multibeam interferometry zhao2022navigation
• Figure 2: A Non-Reciprocal Polarization Phase Shifter based RFOG system (NRPPS-RFOG) with two-coupler FRR configuration (top), one-coupler FRR configuration (below).
• Figure 3: Schematic of the Non-Reciprocal Polarization-Dependent Phase Shifter (NRPPS) showing the propagation of clockwise (CW) and counter-clockwise (CCW) beams: the transmission-type (top) and the reflection-type (bottom).
• Figure 4: $\Delta P$ variation over different $R$ values for $\phi_{NRPPS1} = \pi/2$ (left), $\Delta P$ variation over different $\phi_{NRPPS1}$ values for $R = 0.5$ (right)
• Figure 5: $\Delta P$ variation over $-2\pi$ to $2\pi$ for $\phi_{NRPPS1} = \pi/2$ and $R = 0.5$ values (left), $\Delta P$ variation over different $R$ values for $\phi_{NRPPS1} = \pi/2$ and $\phi_{opt.NRPPS} = \pi$