Microscopic Theory for the Incoherent Resonant and Coherent Off-Resonant Optical Response of Tellurium

TL;DR

This paper presents a first-principles microscopic approach to analyze Tellurium's nonlinear optical response, including absorption, emission, and high-harmonic generation, aligning well with experimental data.

Contribution

It introduces a comprehensive ab initio method combining density functional theory and quantum equations to study Tellurium's optical properties under various excitation conditions.

Findings

Accurate bandstructure and optical spectra matching experiments.

Prediction of high-harmonic generation under ultrafast excitation.

Analysis of emission spectra for different sample thicknesses.

Abstract

An $\it{ab \,\, initio}$ based fully microscopic approach is applied to study the nonlinear optical response of bulk Tellurium. The structural and electronic properties are calculated from first principles using the shLDA-1/2 method within density functional theory. The resulting bandstructure and dipole matrix elements serve as input for the quantum mechanical evaluation of the anisotropic linear optical absorption spectra yielding results in excellent agreement with published experimental data. Assuming quasi-equilibrium carrier distributions in the conduction and valence bands, absorption/gain and spontaneous emission spectra are computed from the semiconductor Bloch and luminescence equations. For ultrafast intense off-resonant excitation, the generation of high-harmonics is evaluated and the emission spectra are calculated for samples of different thickness.