Efficient generation of far-infrared radiation from a periodically poled LiNbO_3 waveguide based on surface-emitting geometry

Abstract

We investigate efficient generation of far-infrared (far-IR) radiation in 13–30 μm based on difference-frequency generation in a periodically poled LiNbO3 waveguide. The efficient conversion is made possible by utilizing a surface-emitting geometry under which the two incoming optical waves propagate along a waveguide, whereas the far-IR radiation is emitted from the waveguide surface. Under such a configuration, we can exploit the enhancements to the second-order nonlinear coefficients due to polariton resonances in the far-IR region. Based on our estimates, the average output power is expected to reach 2.1 mW.