Tunable 2μm dual-wavelength PPLN optical parametric oscillator intra-cavity pumped by passive Q-switched Nd:YLF lasers

摘要

In this paper, we demonstrated passive Q-switched 2μm dual-wavelength intra-cavity PPLN optical parametric oscillators (OPOs) with the advantages of compactness, large tuning range, and narrow linewidth. By using c-cut Nd:YLF crystal as the gain medium, the output power of the fundamental laser at 1053nm can reach up to 0.916W, corresponding to the incident pump power of 9.79W. When the temperature of PPLN crystal was varied between 40°C and 160°C, the orthogonal polarized dual-wavelength lasers can be tuned from 2026.4nm to 2193.9nm. The peak power and optical-to-optical conversion efficiency are 27kW and 9.4%, respectively. As to the a-cut situation, the output power at the fundamental wavelength of 1047nm is about 1.192W. In the same temperature range, two orthogonal polarized wavelengths can be tuned from 1991.8nm to 2206.8nm. The peak power and the optical-to-optical conversion efficiency-are 23.2kW and 12.2%. respectively. Such type-Ⅱ OPOs with an 80-mm total cavity length have potential abilities to work for the generation of terahertz (THz) waves based on difference frequency generation (DFG) and the portable 2-μm-laser based applications of sensing, spectroscopy. imaging, and so on.