Detection of terahertz frequency radiation via the photothermoelastic response of zincblende crystals

Abstract

We present experimental evidence for a photothermoelastic response in zincblende crystals illuminated by quantum cascade laser sources in the frequency range 2.2-2.9 THz. Results obtained using an optically balanced sampling arrangement indicate a mechanism whereby the stress distribution established through localized heating of the crystal induces a change in optical birefringence via the photoelastic response of the crystal. A full mathematic model of this photothermoelastic mechanism in (110)-orientated crystals is presented, and shown to agree well with experimental measurements of the magnitude, and the orientational and spatial dependencies of the sampled signal in ZnTe and GaP crystals.