Silicon carbide--a high-transparency nonlinear material for THz applications.

Optical properties of 4H-SiC were measured using time-domain and Fourier transform spectroscopy in the range of 0.1-20 THz. A high-transparency region was found between <0.1-10 THz. Based on the obtained data and published results, the refractive indices for o-wave and e-wave were approximated in the form of Sellmeier equations for the entire transparency range. Phase matched frequency conversion was found to be possible at wavelengths from the visible through the mid-IR and further into the far-IR (THz) region beyond 17 μm. Extremely low absorption coefficient, high damage threshold, and the possibility of phase matching make this material highly suited for high power THz optics and generation.