Influence of Two-Photon Absorption Anisotropy on Terahertz Emission Through Optical Rectification in Zinc-Blende Crystals

We report for the first time on the observation of an angular anisotropy of the THz signal generated by optical rectification in a < 111 > ZnTe crystal. This cubic (zinc-blende) crystal in the orientation exhibits both transverse isotropy for optical effects involving the linear χ (1) and non...

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Veröffentlicht in:Journal of infrared, millimeter and terahertz waves millimeter and terahertz waves, 2018-04, Vol.39 (4), p.378-386
Hauptverfasser: Sanjuan, Federico, Gaborit, Gwenaël, Coutaz, Jean-Louis
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Sprache:eng
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Zusammenfassung:We report for the first time on the observation of an angular anisotropy of the THz signal generated by optical rectification in a < 111 > ZnTe crystal. This cubic (zinc-blende) crystal in the orientation exhibits both transverse isotropy for optical effects involving the linear χ (1) and nonlinear χ (2) susceptibilities. Thus, the observed anisotropy can only be related to χ (3) effect, namely two-photon absorption, which leads to the photo-generation of free carriers that absorb the generated THz signal. Two-photon absorption in zinc-blende crystals is known to be due to a spin-orbit interaction between the valence and higher-conduction bands. We perform a couple of measurements that confirm our hypothesis, as well as we fit the recorded data with a simple model. This two-photon absorption effect makes difficult an efficient generation, through optical rectification in zinc-blende crystals, of THz beams of any given polarization state by only monitoring the laser pump polarization.
ISSN:1866-6892
1866-6906
DOI:10.1007/s10762-018-0468-4