Fig. 1. Resonant optical gyroscope based on a multi-mode co-detection scheme. (a) Basic schematic diagram of the monolithically integrated resonant optical gyroscope. SLD, super-luminescent diode; Y-branch PM, push-pull Y-branch phase modulator; PD, photodetector. Detection circuit: including modulation-demodulation module and filtering module. (b) Filtering characteristic of the high-Q multi-mode microcavity. (c) Decomposition of multi-mode cavity response spectra according to those non-degenerate modes. (d) Fundamental detection mechanism employed by the multi-mode co-detection scheme.

Fig. 2. Photographs of the high-Q microcavity. (a) Photograph of the polished microcavity with a diameter of 9.2 mm. (b) Photograph of the polished microcavity packaged in a brass module with a thermoelectric cooler and coupling fibers.

Fig. 3. Spectral scanning measurement of a 9.2 mm diameter MgF2 microcavity and comparisons between the microcavity’s equivalent spectra, response curves, and demodulation curves after multi-mode superposition. (a) Measured resonance curve of the microcavity swept with a narrow linewidth laser. (b) High-resolution zoom-in scan of the three spectra labelled A, B, and C, with the loaded Q indicated and equivalent spectra after multi-mode superposition. (c) Comparison of microcavity response curves for single-mode (Q=7.3×108) detection and multi-mode co-detection. (d) Comparison of the demodulation curves between the multi-mode co-detection scheme and the single-mode detection scheme.

Fig. 4. System diagram of the static and rotational measurement. SLD, super-luminescent diode; CIR, circulator; Y-branch PM, push-pull Y-branch phase modulator; PD, photodetector; FPGA, field-programmable gate array; A/D, analog-to-digital converter; D/A, digital-to-analog converter; LPF, low-pass filter; PC, personal computer.

Fig. 5. Performance of the gyroscope. (a) Measured Earth rotation. (b) Long-term test result of the gyro output without additional temperature control conditions. (c) Allan deviation analysis of the gyro output. (d) Output of the gyroscope over rapid temperature changes.

Fig. 6. Dynamic performance of the gyroscope. (a) The output of the gyroscope under sinusoidal oscillations of the platform. (b) The output of the gyroscope in response to the rotating platform at speeds ranging from ±1deg/s to ±1000deg/s. (c) A comparison between the test results and the simulation results.

Fig. 7. Noise analysis of the resonant optical gyroscope based on the multi-mode co-detection technique and predictive analysis of the theoretical sensitivity of such gyroscopes. (a) Fraction of various noises within the system at different modulation frequencies. (b) Relationship between the theoretical sensitivity and the value of Qe×ρe.