Fig. 1. Schematic diagram of the experimental setup. FR, Faraday rotator; P, polarizer; HWP, half-wave plate; QWP, quarter-wave plate; F, lens; M, reflector.

Fig. 2. Pump pulse parameters: (a) typical time domain waveform and output spot of the pump pulse; (b) pump pulse linewidth.

Fig. 3. Interaction distance diagram, where L_S is the interaction length and f is the focal length of the lens.

Fig. 4. Relationship between energy reflectivity and pump energy at different focal lengths: (a) interaction length 90 mm; (b) interaction length 50 mm.

Fig. 5. At the interaction length of 90 mm: the spatial profile of Stokes pulses at different focal lengths with pump energies of 3 and 5 mJ, respectively.

Fig. 6. With a focal length of 200 mm, output energy as a function of pump energy at different interaction lengths.

Fig. 7. With a focal length of 200 mm, the typical spatial profile of Stokes pulses at different pump energies for interaction lengths of 50 and 90 mm, respectively.

Fig. 8. With a focal length of 200 mm, the diameter of spot versus pump energy for different interaction lengths: (a) diameter in the x-axis direction; (b) diameter in the y-axis direction.

Fig. 9. With different focal length conditions: (a) interaction length of 90 mm; (b) interaction length of 50 mm.

Fig. 10. Output pulse duration characteristics at the focal length of 200 mm: (a) output pulse duration versus pump energy for different interaction lengths; (b), (c) output pulse waveforms with the shortest duration for interaction lengths of 50 and 90 mm, respectively.

Fig. 11. Stokes beam quality M² and spatial profile at pump energy of 3.5 mJ.