Optical second harmonic generation from Wannier excitons

TL;DR

This paper develops a simplified model to accurately predict the second harmonic generation in semiconductors, revealing significant enhancement near the transparency region, aligning well with experimental data.

Contribution

It introduces a closed-form expression for the second harmonic response including broadening effects using a three-band Wannier exciton model.

Findings

Calculated spectra match experimental results near the band edge.

Predicted substantial enhancement of nonlinear response in the transparency region.

Model provides a simplified yet accurate approach for excitonic effects in nonlinear optics.

Abstract

Excitonic effects in the linear optical response of semiconductors are well-known and the subject of countless experimental and theoretical studies. For the technologically important second order nonlinear response, however, description of excitonic effects has proved to be difficult. In this work, a simplified three-band Wannier exciton model of cubic semiconductors is applied and a closed form expression for the complex second harmonic response function including broadening is derived. Our calculated spectra are found to be in excellent agreement with the measured response near the band edge. In addition, a very substantial enhancement of the nonlinear response is predicted for the transparency region.