High-Peak Power, Q-Switched Nd:YLF Laser End-Pumped by a Diode Laser Bar

We report on a diode laser-pumped, Q-switched Nd:YLF (Yttrium-Lithium-Fluoride) laser oscillator end-pumped by a fiber-optically coupled, 50-W, quasi- cw diode laser bar. Both pulse-transmission mode (PTM) and pulse-reflection mode (PRM) Q-switching techniques have been realized. In PTM operation the laser produces 1047-nm TEM00 laser pulses with variable duration of 2.4 - 8.4 ns and an energy of about 0.1 mJ, corresponding to ~40 kW of maximum peak power. A novel two-sided longitudinal pumping geometry was investigated in this setup. In PRM operation, a divergence reduction of the diode laser emission has been achieved by a collimating micro-lens. The laser produces 3-mJ/14-ns pulses (210 kW of peak power) at an optical efficiency of 15.5% and a (optical) slope efficiency of 18%. The laser can be operated at repetition rates up to 100 Hz.