Resonantly Enhanced Second-Harmonic Generation Using III–V Semiconductor All-Dielectric Metasurfaces

TLDR

Nonlinear optics in nanostructured materials can achieve orders‑of‑magnitude higher frequency‑conversion efficiencies than bulk media by independently controlling field confinement, enhancement, and scattering, while dielectric resonator metamaterials offer further advantages over plasmonics due to their larger mode volumes and negligible phase‑matching constraints. Here, we present, for the first time, resonantly enhanced second‑harmonic generation using gallium arsenide based dielectric metasurfaces. The authors fabricate arrays of cylindrical GaAs resonators that support magnetic dipole resonances to drive second‑harmonic generation. The metasurfaces exhibit SHG enhancement up to 10⁴ over unpatterned GaAs, achieving an absolute conversion efficiency of ~2×10⁻⁵ at 3.4 GW cm⁻², with polarization measurements revealing significant contributions from both bulk and surface nonlinearities.

Abstract

Nonlinear optical phenomena in nanostructured materials have been challenging our perceptions of nonlinear optical processes that have been explored since the invention of lasers. For example, the ability to control optical field confinement, enhancement, and scattering almost independently allows nonlinear frequency conversion efficiencies to be enhanced by many orders of magnitude compared to bulk materials. Also, the subwavelength length scale renders phase matching issues irrelevant. Compared with plasmonic nanostructures, dielectric resonator metamaterials show great promise for enhanced nonlinear optical processes due to their larger mode volumes. Here, we present, for the first time, resonantly enhanced second-harmonic generation (SHG) using gallium arsenide (GaAs) based dielectric metasurfaces. Using arrays of cylindrical resonators we observe SHG enhancement factors as large as 10(4) relative to unpatterned GaAs. At the magnetic dipole resonance, we measure an absolute nonlinear conversion efficiency of ∼2 × 10(-5) with ∼3.4 GW/cm(2) pump intensity. The polarization properties of the SHG reveal that both bulk and surface nonlinearities play important roles in the observed nonlinear process.