Enhanced second-harmonic generation from L-shaped AlGaAs nanoantennas

Abstract

Nanostructured materials offer many advantages over bulk materials in nonlinear optical phenomena. For example, the subwavelength scale allows the neglect of phase-matching issues. The ability to control tight confinement and large resonant enhancement of electromagnetic fields also results in higher nonlinear frequency conversion efficiencies than bulk materials. Compared with plasmonic nanostructures, high-index dielectric nanostructures render larger mode volumes and show great promise for enhanced nonlinear optical processes. In this work, we present resonantly enhanced second-harmonic generation from L-shaped AlGaAs nanoantennas. By tuning the nanostructure thickness, arm length, and width, the overlap of resonances at fundamental and second-harmonic wavelengths can be achieved using any pump wavelength in a broad near-infrared spectral region. We predict SHG efficiency exceeding 4 × 10 − 3 with a pump intensity of 1 G W / c m 2 at two representative pump wavelengths of 1675 and 1800 nm. Our findings are valuable for applications involving all-dielectric nanoantennas, such as efficient sensing and single biomolecule tracking microscopy.