Broadband mid-infrared frequency upconversion and spectroscopy with an aperiodically poled LiNbO3 waveguide.

We convert a mid-infrared frequency comb to near-infrared wavelengths through sum-frequency generation with a 1.064 μm CW laser in an aperiodically poled ZnO:LiNbO(3) waveguide. Upconversion of light in the range of 2.5-4.5 μm to 0.76-0.86 μm is demonstrated in a single device, and the efficiency of the conversion is measured across this bandwidth. We additionally characterize the spatial mode of the upconverted light. We then use this upconversion technique to detect and resolve individual lines from a methane gas sample with a common near-infrared optical spectrum analyzer. The stability of the spectrum of the upconverted light is analyzed with the goal of evaluating this technique for precise spectroscopic measurements.