Linear and nonlinear optical characterization of tellurium dioxide (α-TeO₂) for generation of terahertz radiation...

This paper reports the linear and nonlinear optical characterization of α-T e O 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=280m m 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.