Doubly resonant photonic crystal cavities for efficient second-harmonic generation in III-V semiconductors

TL;DR

This paper presents a design strategy for doubly resonant photonic crystal cavities that significantly enhance second-harmonic generation efficiency in III-V semiconductors, enabling more effective nonlinear optical devices.

Contribution

It introduces an evolutionary optimization approach combined with Maxwell solvers for designing low-volume, high-Q doubly resonant nanocavities applicable across various material platforms.

Findings

Designs achieve high second-harmonic conversion efficiency in GaN and AlGaAs.

The approach is versatile and can be applied to different semiconductor materials.

Results suggest potential for compact, efficient nonlinear photonic devices.

Abstract

Second-order nonlinear effects, such as second-harmonic generation, can be strongly enhanced in nanofabricated photonic materials when both fundamental and harmonic frequencies are spatially and temporally confined. Practically designing low-volume and doubly resonant nanoresonators in conventional semiconductor compounds is challenging owing to their intrinsic refractive index dispersion. In this work we review a recently developed strategy to design doubly resonant nanocavities with low mode volume and large quality factor by localized defects in a photonic crystal structure. We build on this approach by applying an evolutionary optimisation algorithm in connection with Maxwell equations solvers, showing that the proposed design recipe can be applied to any material platform. We explicitly calculate the second-harmonic generation efficiency for doubly resonant photonic crystal cavity designs in typical III-V semiconductor materials, such as GaN and AlGaAs, targeting a fundamental harmonic at telecom wavelengths, and fully accounting for the tensor nature of the respective nonlinear susceptibilities. These results may stimulate the realisation of small footprint photonic nanostructures in leading semiconductor material platforms to achieve unprecedented nonlinear efficiencies.