Resonant Chiral Effects in Nonlinear Dielectric Metasurfaces

Abstract

We study the resonant enhancement of linear and nonlinear chiroptical effects in planar silicon metasurfaces with an in-plane asymmetry supporting multipolar Mie resonances and quasi-bound states in the continuum (quasi-BICs). We demonstrate theoretically and observe in experiment the pronounced linear circular dichroism at the quasi-BIC resonances originating from the interaction of modes with the substrate. We further find that both local field enhancement and third-harmonic signal are large for Mie resonances and some quasi-BIC modes due to the critical coupling. We demonstrate experimentally a strong nonlinear chiroptical response associated with high efficiency of the third-harmonic generation and large nonlinear circular dichroism varying from +0.918 ± 0.049 to −0.771 ± 0.004 for the samples with different asymmetries. We reveal the nonreciprocal nature of nonlinear chirality governed by the microscopic symmetry of nonlinearities and macroscopic symmetries of the meta-atom and metasurface lattice. We believe our results suggest a general strategy for engineering nonlinear chiroptical response in dielectric resonant metasurfaces.

Nonlinear chiral metaphotonics: a perspective

“…The pioneering experimental observations of chiral nonlinear BICs for strong nonlinear CD have been reported only recently 46 , 90 . Shi et al 46 .…”

“…Another paper 90 focused on the study of the impact of different kinds of high-Q optical resonances in dielectric metasurfaces on nonlinear optical activity, and maximization of the TH efficiency and TH CD simultaneously by virtue of quasi-BICs and other photonic resonances. The authors studied an Si metasurface composed of L-shaped asymmetric particles with the asymmetry defined as dL=S2−S1; see the schematic and SEM image in the left panels of Fig.…”

“…89 The pioneering experimental observations of chiral nonlinear BICs for strong nonlinear CD have been reported only recently. 46,90 Shi et al 46 studied an Si metasurface composed of a square lattice of asymmetric meta-atoms, with the schematic and SEM images shown in the top and bottom left panels of Fig. 5(a).…”

Advances in Meta-Optics and Metasurfaces: Fundamentals and Applications

“…Previous efforts often focused on metallic metasurfaces [ 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 ], which can enhance light–matter interactions and introduce versatile control of incoming light by activating local plasmonic resonance, albeit with limited efficiency due to ohmic loss [ 78 , 79 , 80 , 81 , 82 , 83 ]. Dielectric metasurfaces overcome the limitation of metallic metasurfaces, which have provided a promising way to develop highly efficient and multi-functional meta-devices [ 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 , 100 ].…”

High‐Q and Strong Chiroptical Responses in Planar Metasurfaces Empowered by Mie Surface Lattice Resonances

“…In order to realize strong chiral light-matter interactions, which are usually too weak in natural materials for practical applications, artificial sub-wavelength structures such as metamaterials, metasurfaces, and plasmonic nanostructures have attracted growing attention. [1][2][3][4][5][6][7] In many applications of chiral nanophotonics, such as biochemical chiral sensing, [8][9][10][11][12] chiral emission or lasing, [13][14][15][16] and chiral nonlinear responses, [17][18][19] strong optical chirality and simultaneously high quality (Q) factors are highly desirable but are challenging to achieve.…”