Fig. 1. Schematic of integrated active optical gyroscope^[17]

Fig. 2. Section diagram of resonator structure for gain mechanism of stimulated Raman scattering^[18]

Fig. 3. Structure of three-dimensional vertically coupled resonator^[28]. (a) Top view; (b) side view

Fig. 4. Schematic of circle-coupled resonators for dispersion gyroscope^[43]

Fig. 5. Principle and structure design of fast optical gyroscope^[47]. (a) Principle of fast light enhancing beat frequency of gyroscope; (b) structure of on chip fast light gyroscope

Fig. 6. Schematic of resonant linewidth broadening under abnormal dispersion condition

Fig. 7. Detecting mode broadening induced by rotation rate^[51]. (a) Schematic of microresonator coupled with dispersion slot cavity; (b) transmission and reflection spectra broadened under different rotation rates

Fig. 8. Non-Hermitian optical gyroscope structures. (a) PT-symmetric laser gyroscope structure^[63]; (b) a ring resonator with a periodic complex refractive indices structure^[64]; (c) three-order exceptional points based optical gyroscope structure^[66]; (d) anti-PT-symmetric optical gyroscope structure^[67]

Fig. 9. Experimental schemes of non-Hermitian optical gyroscopes. (a) Non-Hermitian laser gyroscope^[68]; (b) frequency splitting sensitivity enhancement of non-Hermitian and traditional laser gyroscopes^[68]; (c) schematic of non-Hermitian simulated Brillouin gyroscope^[69]; (d) frequency splitting sensitivity enhancement of non-Hermitian and traditional simulated Brillouin gyroscopes^[69]; (e) schematic of on chip non-Hermitian stimulated Brillouin gyroscope structure^[10]; (f) angular random walk of non-Hermitian simulated Brillouin gyroscope^[10]

Fig. 10. Schematic of exceptional surface^[70]

Fig. 11. Several optical structures to realize exceptional surface. (a) Microresonator is coupled to a straight waveguide with a mirror at one end to provide directional coupling from clockwise to counterclockwise modes^[70]; (b) optical microsphere cavity is coupled with directional conical fiber^[71-72]; (c) third order exceptional surface optical structure including two optical cavities coupled with directional conical fiber^[73]

Fig. 12. Non-Hermitian optical gyroscope based on exceptional surface^[74]. (a) Gyroscope structure and microcavity coupled tapered fiber, partial reflector on one side and phase shift Bragg grating on the other side; (b) diagram of an exceptional surface, the exceptional surface shows that the system operating point moves on the surface when the system is subjected to an unexpected disturbance; (c) coupling between clockwise and counterclockwise modes in the stationary and rotating cavities