Mid-infrared difference-frequency generation in periodically poled KTiOAsO(4) and application to gas sensing.

Tunable mid-infrared radiation (3.45-3.75 microm) with a power level of 0.

Multiple nonlinear optical interactions with arbitrary wave vector differences.

We present a novel method for simultaneously phase matching several nonlinear optical interactions within a single crystal. Quasiperiodic modulation of the nonlinear coefficient enables one to achieve high frequency mixing efficiencies for interactions with arbitrary wave vector differences. Doubling of two different frequencies as well as direct frequency tripling is experimentally demonstrated.