Enhanced second harmonic generation from resonant GaAs gratings

TL;DR

This paper demonstrates significant enhancement of second harmonic generation in GaAs gratings by exciting guided mode resonances, achieving efficiencies vastly superior to bulk or etalon structures, even with strong absorption at the harmonic wavelength.

Contribution

It introduces a method to greatly improve second harmonic conversion efficiency in GaAs gratings via resonant excitation of guided modes.

Findings

Conversion efficiencies are approximately five orders of magnitude higher than in bulk GaAs.

Sharp resonances in the spectrum lead to local field enhancements.

Effective even in regimes with strong linear absorption at the harmonic wavelength.

Abstract

We study second harmonic generation in nonlinear, GaAs gratings. We find large enhancement of conversion efficiency when the pump field excites the guided mode resonances of the grating. Under these circumstances the spectrum near the pump wavelength displays sharp resonances characterized by dramatic enhancements of local fields and favorable conditions for second harmonic generation, even in regimes of strong linear absorption at the harmonic wavelength. In particular, in a GaAs grating pumped at 1064nm, we predict second harmonic conversion efficiencies approximately five orders of magnitude larger than conversion rates achievable in either bulk or etalon structures of the same material.