Interference-enhanced optical magnetism in surface high-index resonators: a pathway toward high-performance ultracompact linear and nonlinear meta-optics

Abstract

Artificial magnetism at optical frequencies is one of the most intriguing phenomena associated with metamaterials. The Mie resonance of high-index resonators provides an alternative approach to achieving optical magnetism with simple structures. Given the generally moderate refractive index exhibited by available materials at optical frequencies, Mie resonances usually suffer from coupling between the multipole modes and the corresponding response of the Mie metasurfaces can be analyzed based on the concept of "meta-optics". Here we show that the optical magnetism in high-index resonators can be significantly enhanced by adding a highly reflective back mirror to the system. To highlight the transformative ability of this approach for improving meta-optics in the linear and nonlinear regimes, two proof-ofconcept demonstrations are presented. Theoretical modeling reveals that low-pump power ultrafast nonlinear optics can be realized in periodic Si nanodisk arrays backed with a gold film, a system supporting guided resonance modes. Moreover, based on the enhanced magnetism of individual high-index resonators, a pair of the silicon cuboids is demonstrated as a magnetic antenna for directional excitation of surface plasmon waves. The interference-enhanced magnetism of high-index resonators provides a disruptive technology for enabling meta-optics comprising ultracompact, high-speed and power-efficient photonic devices.

Observation of optical gyromagnetic properties in a magneto-plasmonic metamaterial

“…Therefore, the realization of optical magnetism with μ ≠ 1 and even μ < 0 is of particular interest. Nanostructures including split-ring resonators 9 – 11 , cut-wire pairs 12 , dielectric/metal multilayer metamaterials 13 , 14 , dielectric core-metal nanoparticle “satellite” nanostructures 15 , 16 , and all dielectric resonators 17 , 18 have emerged due to the realization of optical magnetism in recent years. Strong magnetic properties are observed at optical frequencies, leading to the realization of hyperlenses 19 , topological transitions 20 , and interface-bound plasmonic modes 21 , 22 .…”

Observation of optical gyromagnetic properties in a magneto-plasmonic metamaterial

“…Therefore, the realization of optical magnetism with µ ≠ 1 and even µ < 0 is of particular interest. Nanostructures including split-ring resonators [9][10][11] , cut-wire pairs 12 , dielectric/metal multilayer metamaterials 13,14 , dielectric core-metal nanoparticle "satellite" nanostructures 15,16 , and all dielectric resonators 17,18 have emerged due to the realization of optical magnetism in recent years. Strong magnetic properties are observed at optical frequencies, leading to the realization of hyperlenses 19 , topological transitions 20 , and interface-bound plasmonic modes 21,22 .…”

Nonlinear Chiral Meta-Mirrors: Enabling Technology for Ultrafast Switching of Light Polarization

“…37,38 We have recently shown that this approach can also be exploited to facilitate low-switchingpower ultrafast metadevices, which arise from high-quality (Q)-factor spectra as well as strong field confinement. 39 It should be noted that a highly reflective mirror has also been used to achieve an enhanced optical effect in photonic crystal slabs that support guided resonances. 40 In this work, we demonstrate all-optical picosecond light polarization switching with an ultrathin nonlinear chiral metamirror consisting of a 2D array of α-Si split-ring resonators on top of a silver backplane, with a thin silica spacer layer in between.…”

“…stimulus than that of a metal. However, as Mie resonances of nanostructures are primarily determined by their dielectric properties, the performance of all-dielectric metasurfaces is generally limited due to the relatively moderate values of the refractive index that are available in optical materials. , In addition, it has been established that Mie resonances in dielectric nanostructures can be dramatically enhanced by adding a reflective backplane, which serves to facilitate interference effects in the vertical dimension. , We have recently shown that this approach can also be exploited to facilitate low-switching-power ultrafast metadevices, which arise from high-quality (Q)-factor spectra as well as strong field confinement . It should be noted that a highly reflective mirror has also been used to achieve an enhanced optical effect in photonic crystal slabs that support guided resonances …”