Linear and Second-order Optical Response of the III-V Mono-layer Superlattices

TL;DR

This paper presents fully self-consistent calculations of the nonlinear optical properties of III-V mono-layer superlattices, revealing strain-induced anisotropy and emphasizing the importance of supercell calculations for accurate second-order response analysis.

Contribution

It introduces a comprehensive computational approach for analyzing the nonlinear optical response of mono-layer superlattices, improving upon existing models.

Findings

Strain causes significant anisotropy in optical properties.

Superlattice features are more prominent in second-order responses.

Full supercell calculations are essential for accurate second-order optical properties.

Abstract

We report the first fully self-consistent calculations of the nonlinear optical properties of superlattices. The materials investigated are mono-layer superlattices with GaP grown on the the top of InP, AlP and GaAs (110) substrates. We use the full-potential linearized augmented plane wave method within the generalized gradient approximation to obtain the frequency dependent dielectric tensor and the second-harmonic-generation susceptibility. The effect of lattice relaxations on the linear optical properties are studied. Our calculations show that the major anisotropy in the optical properties is the result of strain in GaP. This anisotropy is maximum for the superlattice with maximum lattice mismatch between the constituent materials. In order to differentiate the superlattice features from the bulk-like transitions an improvement over the existing effective medium model is proposed. The superlattice features are found to be more pronounced for the second-order than the linear optical response indicating the need for full supercell calculations in determining the correct second-order response.