Linear and nonlinear optical characterization of tellurium dioxide (α-TeO 2 ) for generation of terahertz radiation using time-domain spectroscopy

This paper reports the linear and nonlinear optical characterization of α −TeO 2 crystal in the optical and terahertz domains for efficient terahertz (THz) generation using a difference frequency mixing technique. We have ascertained the optical properties such as refractive index, absorption coefficients, real and imaginary dielectric constants, and coherence length l c =280mm at 1.77 THz range using an indigenously developed THz spectrometer. The value of refractive index was ascertained from temporal and spectral THz profiles of the crystal and employed for calculating the Type I phase-matching angle, i.e., θ =21.15 ∘ for the generation of tunable radiation between the 0.1 and 1.9 THz range. The figure of merits in the optical and THz domains lie between the 0.02–0.015 range. The effective bandwidth of the crystal lies between the 0.1 and 3.0 THz range.