Higher-Order Harmonic Generation caused by Elliptically Polarized Electric Fields in Solid-State Materials

TL;DR

This paper theoretically explores how the ellipticity of electric fields influences higher-order harmonic generation in solid materials, revealing distinct behaviors across different electronic regimes and potential experimental signatures.

Contribution

It introduces a theoretical framework analyzing HHG dependence on ellipticity in various regimes, highlighting unique polarization characteristics in the semimetal regime.

Findings

HHG intensity decreases monotonically with ellipticity in multiphoton and ac Zener regimes

HHG intensity peaks at finite ellipticity in the semimetal regime

Polarization of emitted HHG varies with regime and field intensity

Abstract

We theoretically investigated the dependence of higher-order harmonic generation (HHG) in solid-state materials on the ellipticity of the electric field. We found that in the multiphoton absorption and ac Zener regimes, the intensity of HHG monotonically decreases with increasing ellipticity of the incident electric field, while in the semimetal regime, the intensity reaches a maximum for finite values of ellipticity. Moreover, the characteristics of the polarization of the emitted HHG change depending on the field intensity; only parallel emissions with respect to the major axis exist in the multiphoton absorption and ac Zener regimes, while both parallel and perpendicular emissions exist in the semimetal regime. These peculiar characteristics of the semimetal regime can be understood on the basis of changes in the HHG mechanism and may be able to be identified in experiments utilizing solid-state materials such as narrow-gap semiconductors.