High-power source of coherent picosecond light pulses tunable from 0.41 to 12.9 ?m

Abstract

We report a high-power source of coherent picosecond light pulses based on optical parametric generation and amplification in LiB3O5 and AgGaS2 crystals. The spectral range of this continuously tunable source covers the visible, near-infrared and medium-infrared spectrum from 0.41 to 12.9 μm. An optical parametric generator and amplifier, consisting of two type-I phase-matched LiB3O5 crystals and a diffraction grating, is pumped by the third harmonic of a picosecond Nd:YAG laser and provides spectrally narrow, high-power pulses from 0.41 to 2.4 μm. Energy conversion efficiencies up to 16 percent are achieved. The pulse duration is about 14 ps, the bandwidth between 10 and 30 cm−1. The tuning range is extended to 12.9 μm by mixing the infrared output between 1.16 and 2.13 μm with the fundamental of the Nd:YAG laser in type-I-phase-matched AgGaS2 crystals. Up to 25 percent of the pulse energy at 1.064 μm is converted into parametric infrared pulses. Bandwidths between 3 and 8 cm−1 and a pulse duration of approximately 19 ps are measured for these pulses. We also observe a retracing behaviour in the tuning curve of AgGaS2 not reported before.