Hundred-watt Ho:YAG oscillator pumped by high-power Tm:YLF laser with orthogonal cylindrical lenses spot shaping

A hundred-watt, linearly-polarized Ho:YAG oscillator, pumped by a 200 W, home-made and s-polarized Tm:YLF laser, was demonstrated. By utilizing a combination of a half-wave plate (HWP) and a thin-film polarizer (TFP), the Tm:YLF laser was split into two orthogonally polarized parts. Each part was significantly reshaped by a system of orthogonally arranged cylindrical lenses and subsequently used to dual-end pump the oscillator. With a total incident pump power of 183 W, a continuous wave (CW) output power of 101 W at 2.1 μm was achieved, with corresponding slope efficiency and optical-to-optical conversion efficiency (OOCE) of 61.6 % and 55.2 %, respectively. Additionally, the beam quality factors, measured in the x and y directions, were 1.59 and 1.35, respectively. Finally, under Q-switched operation at a repetition rate of 20 kHz, a maximum output power of 97 W was achieved, with a corresponding pulse width of less than 34 ns. The central wavelength of the laser was measured to be 2090.2 nm.