Second and Third harmonic generation in the opaque region of GaAs

TL;DR

This paper reports the experimental observation of second and third harmonic generation in opaque GaAs, revealing how nonlinear mechanisms can be inferred through angular and polarization dependence measurements and supported by numerical modeling.

Contribution

It demonstrates harmonic generation in opaque GaAs and introduces a method to analyze underlying nonlinear mechanisms via angular and polarization dependence.

Findings

Harmonic generation occurs in opaque GaAs with specific angular and polarization dependencies.

Different nonlinear mechanisms, including bulk, magnetic, and surface effects, are identified.

Experimental results align with detailed numerical models.

Abstract

Second and third harmonic generation in the opaque region of a GaAs wafer is experimentally observed both in transmission and reflection. These harmonic components can propagate through an opaque material as long as the pump is tuned to a region of transparency or semi-transparency, and correspond to the inhomogeneous solutions of Maxwell's equations with nonlinear polarization sources. We show that measurement of the angular and polarization dependence of the observed harmonic components allows one to infer the different nonlinear mechanisms that trigger these processes, including bulk nonlinearity, magnetic Lorentz and surface contributions. Experimental results are compared with a detailed numerical model that takes into account these different effects.