Nonlinear circular dichroism in achiral dielectric nanoparticles

Abstract

In this study, we investigate the nonlinear optical phenomena emerging from the interaction of vortex beams with achiral nanoparticles, leading to the observation of nonlinear circular dichroism in the high-harmonic generation. Despite the achiral symmetry of the nanoparticles, the interplay between the vector properties of the light, the symmetry of the nanoparticles, and the symmetry of the crystalline lattice of the nanoparticle material leads to circular dichroism in the nonlinear regime. We derive a formula that describes the conditions for the appearance of circular dichroism across all possible scenarios, taking into account all the symmetries. We also show that the absolute value of the incident beam's orbital angular momentum does not play a major role. We believe that this work provides important insights that can help in improvement the design process of chiral sensors, making them more versatile and effective.

Resonant Chiral Effects in Nonlinear Dielectric Metasurfaces

“…The scanning electron microscope (SEM) image of the meta-atom and metasurface is shown in Figure b. We note that because of the meta-atom shape and substrate presence, the eigenstates of the Jones matrix are elliptically polarized so the structure supports both linear and circular birefringence and dichroism. , As we reveal below, while for the study of linear chiral response meta-atoms possessing a rotational symmetry may be more favorable, for nonlinear response the microscopic symmetry of nonlinearities dominates the effects driven by the symmetry (such as C 4 ) of meta-atoms and metasurfaces. , …”

“…62,63 As we reveal below, while for the study of linear chiral response metaatoms possessing a rotational symmetry may be more favorable, for nonlinear response the microscopic symmetry of nonlinearities dominates the effects driven by the symmetry (such as C 4 ) of meta-atoms and metasurfaces. 29,64 First, we characterize the linear chiroptical response of the fabricated metasurfaces by measuring experimentally copolarized transmission I RCP (ω) and I LCP (ω) . We use selective excitation with a polarized white light and selective collection of the same polarization at the output.…”

Fast Simulation of Light Scattering and Harmonic Generation in Axially Symmetric Structures in COMSOL

“…This approach is valid for noncentrosymmetric materials such as gallium arsenide 30,99−103 or lithium niobate, 104−110 and we will limit our consideration to them in this paper. Already at this point, it becomes clear that despite of cylindrical symmetry of the scatterer, the nonlinearity of the problem and the symmetry of the tensor "mixes" the input harmonics with different m. 86,111 One should not be discouraged by this fact; our method still can be applied here once proper expansion of the nonlinear tensor is carried out and the incident field's frequency is doubled.…”

Nonlinear chiral metaphotonics: a perspective

“…4(c). This work led to theoretical analysis of conditions for nonzero SH CD in individual nanoparticles and oligomers depending on the atomic lattice orientation and macroscopic symmetry of the metamolecule, 81 based on earlier knowledge of selection rulers for nonlinear processes in nanostructures of different shapes 82 , 83 …”

“…4(c). This work led to theoretical analysis of conditions for nonzero SH CD in individual nanoparticles and oligomers depending on the atomic lattice orientation and macroscopic symmetry of the metamolecule, 81 based on earlier knowledge of selection rulers for nonlinear processes in nanostructures of different shapes. 82,83 Recent works also include theoretical analysis of intensitydependent nonlinear chiroptical response driven by GMR modes in Si metasurfaces 84 and numerical study of chiral SHG in LN metasurfaces with Z-shaped meta-atoms in a square lattice on gold substrates.…”