Fig. 1. Schematic diagrams of bow-tie cavity and its overall mechanical structure. (a) Optical path; (b) mechanical structure

Fig. 2. Theoretical simulation of relationship between transmittance of input coupler and output power of 253.7 nm laser

Fig. 3. Experimental setup of deep-ultraviolet laser system (PDH: Pound-Drever-Hall; AOM: acoustic optical modulator; AF: attenuation filter; PPLN: periodically poled lithium niobate; ECDL: external cavity diode laser; TC: transfer cavity; USL: ultra-stable laser; OPLL: optical phase-locked loop; PD: photodetector; PID: proportion-integration-differentiation controller; PMF: polarization-maintaining fiber; FA: fiber laser amplifier; HWP: half-wave plate; PZT: piezoelectric transducer; PL: positive lens; CL: cylindrical lens; OC: output coupler; NDF: neutral density filter; HR: high-reflection mirror; SF: spatial filter; BD: beam dump; SM: sampling mirror)

Fig. 4. Frequency drift of 1014.8 nm seed light

Fig. 5. 253.7 nm laser power after single pass of 507.4 nm laser through CLBO crystal

Fig. 6. Power and frequency-doubling conversion efficiency curve of deep-ultraviolet laser system and ultraviolet far-field spots. (a) Output power and frequency-doubling conversion efficiency of 253.7 nm deep-ultraviolet laser as a function of 507.4 nm fundamental laser power; (b) far-field ultraviolet spot after spatial filtering; (c) far-field ultraviolet spot before spatial filtering

Fig. 7. RIN values of 507.4 nm laser and 253.7 nm laser. (a) Input power is 335 mW; (b) input power is 1.1 W

Fig. 8. Power variation of deep ultraviolet laser system during continuous operation for 48 h with power stability of deep-ultraviolet laser shown in inset