Abstract
The quest for nanoscale light sources with designer radiation patterns and polarization has motivated the development of nanoantennas that interact strongly with the incoming light and are able to transform its frequency, radiation, and polarization patterns. Here, we demonstrate dielectric AlGaAs nanoantennas for efficient second harmonic generation, enabling the control of both directionality and polarization of nonlinear emission. This is enabled by specialized III–V semiconductor nanofabrication of high-quality AlGaAs nanostructures embedded in optically transparent low-index material, thus allowing for simultaneous forward and backward nonlinear emission. We show that the nanodisk AlGaAs antennas can emit second harmonic in preferential direction with a backward-to-forward ratio of up to five and can also generate complex vector polarization beams, including beams with radial polarization.
Supporting Information
The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.nanolett.6b03525.
Details on fabrication method, optical diagnostics techniques, and numerical optimization and analysis. Figures showing fabrication steps, a schematic of transmission measurements and transmission spectra, a schematic of the experimental setup, experimentally measured SHG and THG planes, schematic of the polarization ellipse, back-focal plane images, components of the Stokes vector, spatially-resolved degree of polarization, inclination and ellipticity, calculated scattering efficiency and multipole decomposition, multipolar contributions to the SH generated field, second harmonic directionality versus nanodisk height for disk diameter, efficiency of the second harmonic versus polarization orientation, and spatial profiles. (PDF)
