Optimizing the Nonlinear Optical Response of Plasmonic Metasurfaces

Abstract

The nonlinear optical response of materials to exciting light is enhanced by resonances between the incident laser frequencies and the energy levels of the excited material. Traditionally, in molecular nonlinear spectroscopy one tunes the input laser frequencies to the molecular energy levels for highly enhanced doubly or triply resonant interactions. With metasurfaces the situation is different, and by proper design of the nanostructures, one may tune the material energy levels to match the incoming laser frequencies. Here we use multi-parameter genetic algorithm methodologies to optimize the nonlinear Four Wave Mixing response, and show that the intuitive conventional approach of trying to match the transmission spectrum to the relevant laser frequencies indeed leads to strong enhancement, but not necessarily to the optimal design. We demonstrate, experimentally and by direct nonlinear field calculations, that the near field mode distribution and spatial modes overlap are the dominant factor for optimized design.

Efficient Frequency Conversion with Geometric Phase Control in Optical Metasurfaces

“…Freed from the constraints of classical nonlinear optics, [ 1 ] nonlinear metasurfaces feature versatile functionalities by manipulating the amplitude, phase, and polarization of the generated light. Past research led to essential applications like higher harmonic generation and wave mixing, [ 2 , 3 ] beam shaping, wavefront control at higher harmonics, [ 4 ] vortex beam generation, [ 5 ] multiplexed holography, [ 6 ] and nonlinear chirality. [ 7 , 8 ] Many of these applications were demonstrated with plasmonic or hybrid plasmonic‐dielectric metasurfaces that are governed by dipole electric or magnetic modes but yield a low conversion efficiency [ 9 , 10 ] in the visible and near‐infrared regime.…”

Second-harmonic generation in nonlinear plasmonic lattices enhanced by quantum emitter gain medium

“…[9] For instance, by manipulating geometrical parameters one can achieve substantial increase in four-wave mixing processes. [10] Both experiment and theory show that the SHG by plasmonic nanoparticles with no center of inversion symmetry is extremely sensitive to particle shape even within few nanometers opening new opportunities to designing functional materials for frequency conversion applications. [11] On the other hand, strong spatial localization of SPPs could be used to investigate how ensembles of quantum emitters (QEs), e.g., organic dyes or semiconductor quantum dots, behave if resonantly coupled to corresponding surface electromagnetic modes.…”

Metamaterial Lensing Devices

“…With the continuous development of micro-nano optics, traditional optical lenses are difficult to meet the requirements of large-scale integration and device miniaturization and functional diversification. Metasurface lenses [90,91,92,93,94] are made of two-dimensional (2D) planar structures that artificially arrange optical antennas with special electromagnetic characteristics in a certain way, which can achieve flexible regulation of amplitude, phase, polarization and other parameters of the incident light. Important applications, such as holographic optics and achromatic lenses, have been triggered.…”