High-energy picosecond single-pass multi-stage optical parametric generator and amplifier

We demonstrate a new management of multi-stage optical parametric generator (OPG) and amplifier (OPA) to obtain high-energy picosecond sources with high beam quality. The setup of multi-stage OPG-OPA requires mode-matching between the pump beam and the stable mode of the OPG-OPA. In a proof-of-principle experiment, the single-pass multi-stage OPG-OPA consists of three walk-off compensated KTP crystal pairs and two lenses, pumped by an 86 ps, 1064 nm 10 kHz picosecond laser. The signal light at ~1.77 μm has an average output power of 502 mW with record energy up to 50.2 μJ. The beam quality factor of the signal light can be improved to M_x^2 \times M_y^2=1.87\times 2.16 after filtering out about 40% signal power. To the best of our knowledge, it is the first picosecond single-pass multi-stage OPG-OPA pumped at kHz regime.