Fig. 1. Zerodur-based full-inner-cavity ring laser resonator. (a) Real photo of large laser gyroscope NUDT-MRLG550 with side length of 0.55 m; (b) schematic of material composition and photo-glue area of ring resonator

Fig. 2. Diffraction loss simulation and loss measurement of different transverse modes. (a) Theoretical diffraction loss values under different diaphragm sizes; (b) cavity ring-down test curves under TEM₀₀ and TEM₀₁

Fig. 3. Finite element simulation of He-Ne plasma dynamics. (a) Electron number density distribution under steady-state condition of He-Ne laser with direct current discharge; (b) breakdown process of He-Ne plasma and steady-state sustaining voltage and operating current; (c) simulation results of reaction rates during He-Ne excitation process; (d) simulation results of reaction rates during spontaneous emission process of Ne atoms; (e) simulation results of inverted particle numbers; (f) single longitudinal mode output intensity values of large laser gyroscope under different pressures

Fig. 4. Laser modes and output signals of NUDT-MRLG550. (a)(b) Laser mode characteristics measured by confocal Fabry-Perot interferometer; (c) beat signals obtained after combining clockwise and counterclockwise beams in laser gyroscope; (d) Fourier transform results corresponding to beat signals