Optical diffraction spectroscopy of excitons in uniaxially-strained GaN films

TL;DR

This study uses optical diffraction spectroscopy to analyze excitons in uniaxially strained GaN films, revealing strain-induced anisotropy and exciton fine structure splittings through nonlinear four-wave mixing techniques.

Contribution

It introduces a novel application of degenerate four-wave mixing spectroscopy to map strain-induced exciton anisotropy in GaN films.

Findings

Enhanced sensitivity to polarized excitons via nonlinear response

Clear observation of exciton fine structure splittings

Correlation between spectral polarization and quantum beating periods

Abstract

The degenerate four-wave mixing spectroscopy of uniaxially strained GaN layers is demonstrated using colinearly polarized laser pulses. The nonlinear response of FWM signal on exciton oscillator strength enhances the sensitivity for polarized exciton, allowing for mapping out the in-plane anisotropy of the strain field. The observed high-contrast spectral polarization clearly shows fine structure splittings of excitons, which are also confirmed in the change of quantum beating periods of time.