A high-energy picosecond 355 nm ultraviolet (UV) laser operating at 100 Hz was demonstrated. A 352 mJ, 69 ps, 1064 nm laser at 100 Hz was realized firstly by cascaded regenerative, laser diode end-pumped single-pass and side-pumped main amplifiers. The stimulated Raman scattering-based beam shaping technique, thermally induced birefringence compensation and 4f spatial filter-image relaying systems were used to maintain a relatively homogeneous beam intensity distribution during the amplification process. By using lithium triborate crystals for second- and third-harmonic generation (THG), a 172 mJ, approximately 56 ps, 355 nm UV laser was achieved with a THG conversion efficiency of 49%. To the best of our knowledge, it is the highest pulse energy of a picosecond 355 nm UV laser so far. The beam quality factor ${M}^2$ and pulse energy stability were ${M}_x^2$=3.92, ${M}_y^2$=3.71 and root mean square of 1.48%@3 hours. This laser system could play significant roles in applications including photoconductive switch excitation, laser drilling and laser micro-fabrication.

Femtosecond oscillators with gigahertz (GHz) repetition rate are appealing sources for spectroscopic applications benefiting from the individually accessible and high-power comb line. The mode mismatch between the potent pump laser diode (LD) and the incredibly small laser cavity, however, limits the average output power of existing GHz Kerr-lens mode-locked (KLM) oscillators to tens of milliwatts. Here, we present a novel method that solves the difficulty and permits high average power LD-pumped KLM oscillators at GHz repetition rate. We propose a numerical simulation method to guide the realization of Kerr-lens mode-locking and comprehend the dynamics of the Kerr-lens mode-locking process. As a proof-of-principle demonstration, an LD-pumped Yb:KGW oscillator with up to 6.17-W average power and 184-fs pulse duration at 1.6-GHz repetition rate is conducted. The simulation had a good agreement with the experimental results. The cost-effective, compact and powerful laser source opens up new possibilities for research and industrial applications.

We report on the study of single-mode fiber-laser-pumped mode-locked Yb:CALYO lasers via using a passive saturable absorber and Kerr-lens mode-locking technique, respectively. Up to 3.1-W average power with 103-fs pulse duration is obtained from the passive mode-locking, and down to 36-fs pulse duration with more than 2-W average power is achieved by the pure Kerr-lens mode-locking, which is to the best of our knowledge, the highest average power from a reported sub-40-fs Yb-based solid-state oscillator.

A composite transparent YAG/Yb:YAG/YAG ceramic was prepared by a non-aqueous tape-casting method. An optical transmittance of 82% was obtained at visible wavelength and around 1100 nm. A low-threshold, broadband tunable continuous-wave (CW) laser at 1031 nm was further demonstrated from the ceramic sample, which was pumped by a 974 nm fiber-pigtailed laser diode. The threshold pump power was 0.45 W and the maximum output power was 3.2 W, corresponding to a slope efficiency of 20.4%. By inserting an SF57 prism in the laser cavity, the output wavelength could be tuned continuously from 1021 to 1058 nm.

A diode-pumped master oscillator power amplifier system based on a cryogenic Yb:YAG active-mirror laser has been developed. The performances of the laser amplifier at low temperature and room temperature have been investigated theoretically and experimentally. A maximum output energy of 3.05 J with an optical-to-optical efficiency of 14.7% has been achieved by using the master amplifier system.