Chiral Assemblies of Achiral Dielectric Nanoparticles: Semianalytical Approach

We report a theoretical modeling on the excitation of chiro-optical activity in chiral assemblies comprising of dielectric nanoparticles using a semianalytical method based on coupled dipole approximation. In stark contrast to plasmonic counterparts where electric dipolar coupling dominates chiro-optical response, our analysis reveals a magnetic-dominated response, which originates from the dynamic electromagnetic coupling between the magnetic dipole moments of the individual high-index dielectric nanoparticles. The calculated circular dichroism response practically remains insensitive to interparticle spacing but shows strong dependence on the size of nanoparticle and refractive index, in close agreement with numerical simulations. Such a chiral assembly represents a novel material platform where individual achiral dielectric nanoparticles with strong magnetic resonances can be exploited as building blocks for engineering new type of chiral light–matter interaction, and being low in light absorption loss, this could be promising for applications in nanophotonics