Anisotropic terahertz optostriction in group-IV monochalcogenide compounds

TL;DR

This paper investigates how terahertz light induces anisotropic elastic deformations in group-IV monochalcogenides, revealing significant strain effects and potential detection methods through shift current measurements.

Contribution

It introduces a thermodynamic and first-principles approach to understand THz-induced deformation and anisotropic optostriction in these materials, highlighting their potential for optomechanical applications.

Findings

THz light causes ~0.1% elastic deformation depending on polarization

Large anisotropic opto-mechanical responses are observed

Strain can be detected via layer-resolved shift current measurements

Abstract

Terahertz (THz) technology is a cutting-edge scheme with various promising applications, such as next generation telecommunication, non-destructive evaluation, security check, and in-depth characterization, owing to their sensitivity to material geometric change and good transparency. Even though tremendous progresses have been made during the past decade, exploration the mechanisms of THz-matter interaction microscopically is still in its infancy. In this work, we use thermodynamic theory to show how THz illumination deforms materials and use group-IV monochalcogenide compounds to illustrate it. According to our first-principles density functional theory calculations, THz light with intermediate intensity (~109 W/cm2) could yield elastic deformations on the order of ~0.1%, depending on laser polarization direction. Large anisotropic opto-mechanical responses are also revealed. Finally, we show that such strain can be detected via measuring the layer-resolved shift current under a probe light irradiation.