Polarization Spectroscopy of High-Order Harmonic Generation in Gallium Arsenide

TL;DR

This study investigates how the polarization dependence of high-order harmonic generation in gallium arsenide varies with laser intensity, revealing microscopic effects that could enable control of electron currents in solid-state devices.

Contribution

It reports the first detailed analysis of the polarization dependence of high-order harmonics in gallium arsenide, highlighting intensity-driven changes linked to microscopic electron dynamics.

Findings

Significant evolution of anisotropic response with laser intensity

Competition between intraband and interband dynamics affects harmonic polarization

Potential for controlling electron currents in solid-state devices

Abstract

An interesting property of high harmonic generation in solids is its laser polarization dependent nature which in turn provides information about the crystal and band structure of the generation medium. Here we report on the linear polarization dependence of high-order harmonic generation from a gallium arsenide crystal. Interestingly, we observe a significant evolution of the anisotropic response of above bandgap harmonics as a function of the laser intensity. We attribute this change to fundamental microscopic effects of the emission process comprising a competition between intraband and interband dynamics. This intensity dependence of the anisotropic nature of the generation process offers the possibility to drive and control the electron current along preferred directions of the crystal, and could serve as a switching technique in an integrated all-solid-state petahertz optoelectronic device.