Polarization-Dependent Second Harmonic Diffraction from Resonant GaAs Metasurfaces

Abstract

Resonant semiconductor metasurfaces are an emerging versatile platform for nonlinear photonics. In this work, we investigate second-harmonic generation from metasurfaces consisting of two-dimensional square arrays of gallium arsenide nanocylinders as a function of the polarization of the fundamental wave. To this end, we perform nonlinear second harmonic microscopy, where the pump wavelength is tuned to the resonances of the metasurfaces. Furthermore, imaging the generated nonlinear signal in Fourier space allows us to analyze the spatial properties of the generated second harmonic. Our experiments reveal that the second harmonic is predominantly emitted into the first diffraction orders of the periodic arrangements, and that its intensity varies with the polarization angle of the fundamental wave. While this can be expected from the structure of the GaAs nonlinear tensor, the characteristics of this variation itself are found to depend on the pump wavelength. Interestingly, we show that the metasurface can reverse the polarization dependence of the second harmonic with respect to an unstructured GaAs wafer. These general observations are confirmed by numerical simulations using a simplified model for the metasurface. Our results provide valuable input for the development of metasurface-based classical and quantum light sources based on parametric processes.

Zero-Order Second Harmonic Generation from AlGaAs-on-Insulator Metasurfaces

“…8,9 In this context, Segal et al have demonstrated the concept of nonlinear metamaterial-based photonic crystals for controlling the direction of SHG by using binary modulation of the nonlinear coefficient, 10 while Lochner et al have recently demonstrated second harmonic generation (SHG) and diffraction from a semiconductor metasurface with FW close to the material band gap. 3 In both studies, for a pump at normal incidence, SHG occurred in the first order with a negligible zero order.…”

Design for quality: reconfigurable flat optics based on active metasurfaces

“…Using light to modulate active metasurfaces often relies upon nonlinear optical interactions such as Kerr nonlinearity, photogenerated free carrier injection, and photothermal effects [228]. It has been established that these nonlinear interactions can be significantly enhanced capitalizing on resonances in metasurfaces [229][230][231][232][233][234][235], and the optical behavior of the meta-atoms is in turn strongly modified by the nonlinear effects [236][237][238][239]. Besides optical nonlinearity, the properties of metasurfaces can also be actively controlled leveraging optical interference between the mutually coherent pump and probe light beams.…”

Recent Progress in Active Optical Metasurfaces

“…Mie resonances of semiconductor resonators have been exploited to enable enhanced nonlinear harmonic generation signals . Compared with the plasmonic resonance associated with metallic nanostructures, the locally enhanced field of Mie resonances occurs primarily within the dielectric resonators, which results in large modal volume that can remarkably increase the nonlinear generation efficiency.…”

“…First, the tensor that only contains off‐diagonal components, and second, the symmetry of GaAs's zincblende lattice structure. Nevertheless, recent studies have shown that the local field manipulation ability offered by Mie resonances can dramatically boost the nonlinear generation from nanoengineered GaAs metasurfaces, in which the nonlinear signals were resonantly enhanced and closely dependent on the excitation conditions such as the polarization of pumping light or the relative time relation between excitation pulses (Figure 9b) . Utilizing a leaky resonance excited in a dielectric resonator lattice, Ha et al recently have reported a directional lasing phenomena in metasurfaces composed of GaAs nanopillars (Figure 9c,d) .…”