Abstract
Tunable laser sources in the mid-infrared (mid-IR) spectral range have been of great interest for a variety of applications such as molecular spectroscopy and trace gas detection. Difference-frequency generation (DFG) based on nonlinear frequency conversion in nonlinear crystals has been an effective approach to realize tunable mid-IR laser sources [1]. Among nonlinear crystals, orientation-patterned (OP) GaAs has been highly attractive for mid-IR DFG laser sources due to its large nonlinear susceptibility, lack of birefringence, wide transparency range (0.9 - 17 μm), high thermal conductivity, and high laser-damage-threshold [2,3]. Here, we report the generation of broadly tunable mid-IR radiation across 12.65 - 15 μm based on the DFG approach using an OP-GaAs crystal.