The effect of heating and drift of electrons in an electric field on the absorption and refraction of terahertz radiation in electronic indium antimonide

The calculation of the refractive index (RI) and absorption coefficient (AC) spectra has been performed for terahertz radiation (λ = 70 — 500 μm) in electronic indium antimonide n-InSb placed in an electric field of up to 200 V/cm. It was done on the basis of solving the Fresnel equation and the Boltzmann kinetic one. The Fermi — Dirac distribution shifted in velocity space was used as a nonequilibrium stationary electron distribution function over states. Changes in optical characteristics obtained in an electric field were shown to be due to the heating and drift of free electrons. Anisotropy of the electron distribution function over states in the momentum space, arising in the electric field, involved the anisotropy of RI and AC. These changes differed for radiation polarized parallel and perpendicular to the field direction. This effect can be used for high-speed modulation of terahertz radiation because it is clearly pronounced.