Simplified bond-hyperpolarizability model of second-harmonic-generation in Si(111): theory and experiment

TL;DR

This paper refines the Simplified Bond-Hyperpolarizability Model (SBHM) to explain second-harmonic-generation in Si(111), combining theoretical development with experimental validation to enhance understanding of nonlinear optical processes in centrosymmetric materials.

Contribution

The paper provides a detailed theoretical description of SBHM for Si(111) and demonstrates its effectiveness through experimental SHG measurements.

Findings

SBHM accurately models SHG in Si(111)

Experimental results agree with theoretical predictions

Enhanced physical understanding of nonlinearity in centrosymmetric materials

Abstract

Second-harmonic-generation (SHG) in centrosymmetric material such as Si(111) is usually understood either from the phenomenology theory or more recently using the Simplified Bond-Hyperpolarizability Model (SBHM) [G. D. Powell, J. F. Wang, and D. E. Aspnes, Phys. Rev. B 65, 205320/1 (2002)]. Although SBHM is derived from a classical point of view, it has the advantage over the former that it gives-especially for lower symmetry systems- a clear physical picture and a more efficient explanation of how nonlinearity is generated. In this paper we provide a step-by-step description of the SBHM in Si(111) for the linear and second harmonic case. We present a SHG experiment of Si(111) and show how it can be modelled by summing up the contribution of the fields produced by the anharmonic motion along the bonds.