Fig. 1. Frequency conversion path of the OPA-based 193 nm laser. OPA, optical parametric amplifier; SHG, second-harmonic generation; FHG, fourth-harmonic generation; SFG, sum-frequency generation.

Fig. 2. Experimental setup of the OPA at 1553 nm. DFB, distributed feedback; PPLN, periodically poled lithium niobate.

Fig. 3. (a) Output powers of 1553 nm laser as the function of pump powers of 1030 nm in OPA 2; (b) optical spectra of the seed laser and amplified signal laser from OPA 1 and OPA 2; (c) linewidth evolution of the 1553 nm laser during OPA processes; (d) pulse shapes of the 1030 nm pump laser and 1553 nm signal laser from OPA 2.

Fig. 4. Output average powers of (a) 515 nm laser and (b) 258 nm laser as the function of pump average powers of 1030 and 515 nm lasers, respectively.

Fig. 5. Output average powers of (a) 221 nm laser and (b) 193 nm laser generated from the first and second SFG in LBO crystal as the function of pump average powers of 258 and 221 nm lasers, respectively; (c) temporal profiles of the 221 and 193 nm lasers.

Fig. 6. Experimental setup of generating 193 nm laser carrying OAM.

Fig. 7. Gaussian mode, LG mode, and the diffraction patterns of the vortex beams of 1553, 221, and 193 nm lasers recorded by a pyroelectricity camera.