Below-bandgap excitation of bulk semiconductors by twisted light

TL;DR

This paper theoretically explores how bulk semiconductors respond to below-bandgap twisted light, revealing unique exciton dynamics, energy shifts, and complex spatial polarization patterns resulting from the light's angular momentum.

Contribution

It introduces a modified light-semiconductor interaction model that incorporates light's momentum conservation, highlighting novel exciton behaviors under twisted light excitation.

Findings

Excited states are superpositions of perturbed excitons with complex motion

Absorption occurs at slightly shifted energies compared to plane wave excitation

Spatial polarization and current patterns are complex and distinctive

Abstract

I theoretically investigate the response of bulk semiconductors to excitation by twisted light below the energy bandgap. To this end, I modify a well-known model of light-semiconductor interaction to account for the conservation of the light's momentum. I show that the excited states can be thought of as a superposition of slightly perturbed exciton states undergoing a complex center-of-mass motion. In addition, the absorption would occur at a slightly shifted energy (compared to plane waves) and would exhibit complex spatial patterns in the polarization and current.