Continuous-wave seeded mid-IR parametric system pumped by the high-average-power picosecond Yb:YAG thin-disk laser

Abstract

Mid-IR wavelength range offers variety of interesting applications. Down-conversion in the optical parametric devices is promising to generate high average power mid-IR beam due to inherently low thermal load of the nonlinear crystals if a powerful and high quality pump beam is available. We developed 100 kHz pump laser of 100-W level average power. The stretched pulses of Yb-fiber laser oscillator at 1030 nm wavelength are injected into the regenerative amplifier with an Yb:YAG thin-disk. Diode pumping at zero phonon line at wavelength of 969 nm significantly reduces its thermal load and increases conversion efficiency and stability. We obtained the beam with power of 80 W and 2 ps compressed pulsewidth. We are developing a watt level mid-IR picosecond light source pumped by a beam of the thin disk regenerative amplifier. Part of the beam pumps PPLN, which is seeded by a continuous wave laser diode at 1.94 μm to decrease the generation threshold and determine the amplified spectrum. The 3 W pumping gave output of 30 mW, which is by up to two orders higher compared to unseeded operation. The gain of about 107 was achieved in the PPLN in the temporal window of the pump pulse. The spectrum and beam of the generated idler pulses in the mid-IR was measured. We obtained an amplified signal from the second stage with the KTP crystal. We expect watt level mid-IR output for initial 50-W pumping. The generation of longer wavelengths is discussed.