Fig. 1. Schematic setup of the high-energy picosecond 355 nm UV laser system. HWP, half-wave plate; OI, optical isolator; BE, beam expander; TFP, thin-film polarizer; FR, Faraday rotator; QWP, quarter-wave plate; PC, Pockels cell; HR, high-reflection mirror; LD, laser diode; DM, dichroic mirror; VT, vacuum tube; MD, Nd:YAG module; CL, compensating lens; QR, 90° quartz rotator.

Fig. 2. (a) Output energies of the master oscillator (MO), regenerative amplifier (RA), single-pass amplifier (SA), first stage of the main amplifier (MA.1), second stage of the main amplifier (MA.2), and third stage of the main amplifier (MA.3). (b) Output beam quality from the RA. The inset shows the near-field beam intensity distribution.

Fig. 3. Intensity distributions of (a) the flat-top center beam and (b) the saddle-shaped concave center beam after being shaped by the single-pass amplifier. (c) Output laser spectra of the flat-top center beam (blue line) and the saddle-shaped concave center beam (red line) from the single-pass amplifier.

Fig. 4. (a) Energy stability of the 1064 nm fundamental laser pulse. (b) Measured beam quality factor at an output energy of 352 mJ. The inset shows the near-field beam intensity distribution. (c) Laser spectra of the seed pulses at an output energy of 2 nJ (black line) and the amplified pulses at an output energy of 352 mJ (red line). (d) Temporal profiles of the seed pulses at an output energy of 2 nJ (black line) and the amplified pulses at an output energy of 352 mJ (red line).

Fig. 5. (a) Dependence of the 532 nm green laser pulse energy and SHG efficiency on the incident 1064 nm laser pulse energy. (b) Energy stability of the 532 nm green laser pulse. (c) Dependence of the 355 nm UV laser pulse energy and THG efficiency on the incident 1064 nm laser pulse energy. (d) Energy stability of the 355 nm UV laser pulse.

Fig. 6. (a) Measured beam quality factor of the 355 nm UV laser at a pulse energy of 172 mJ. The inset shows the near-field beam intensity distribution. (b) Measured temporal pulse profile of the 355 nm UV laser.