Abstract
Continuously tunable mid‐infrared radiation from 3.0 to 5.3 μm was produced by difference frequency mixing in KTiOAsO4. A photon efficiency of 7% for conversion to 4.4 μm was achieved, providing peak power exceeding 250 kW, and pulse energy of over 0.5 mJ in a 2 nanosecond pulse. An absorption spectrum of CO2 in air with better than 1 cm−1 resolution was obtained simply by scanning the wavelength of one of the input lasers.