Generation of unconventional Fano-comb resonances in multilayered core-shell nanoparticles.

We theoretically propose a design of core-shell nanoparticles consisting of a dielectric core coated by several alternating plasmonic and dielectric shell layers for the generation of comb-like scattering resonances. We demonstrate that the obtained scattering resonances are independent of the polarization, observation angle and background medium, since they originate from the unconventional Fano interference between Mie modes with the same multipole moment inside each plasmonic shell layer. Furthermore, we also demonstrate that controlling either the core or the shell parameters can precisely tune the spectral positions of the comb-like resonances. At last, we show that the comb-like resonances can be well maintained even for the non-perfect spherical core-shell nanoparticles. All these features make the proposed multilayered core-shell nanoparticles attractive candidates for multichannel and ultrasensitive optical tags.