Fano Resonance Generated In Dielectric Nanostructures

The localized surface plasmon resonance of metal nanostructure have exhibited uinique optical effects.Properly manipulate the structure parameters or exciting conditions of nanoparticles can result in interfererence between different suface plasmon resonance modes(radiative mode and nonradiative mode),as a result Fano resonance properly be introduced.Fano resonance in suface plasmonic nanoparticles suppress radiative losses effectively.However the intrinsic nonradiative losses(like ohmic loss) in mental nanoparticles restrict futher improvement of its performance.In adition,exciting Fano resonance need to break symmetry,as result it always have complicated structure and very hard to preparation.So for improve the performation of device,it is urgent to overcome the influence of nonradiation and generate Fano resonance that not affected by the polalizition state.Further investigation find that replace mental with high index dielectric materials offer a potential solution to solve the above issues.There are various subradiant hybrid modes in a single dielectric nanoparticles under properly condition.As a result,stong Fano resonance even multiple Fano resonance can be introduced.In addition,the low nonradiative losses in dielectric materials result in its Fano resonance suppress radiative losses as well as nonradiative losses very effectly.This study shows that due to the excitation of the subradiant hybrid EH12δ mode a strong Fano resonance is genearated in a single silicon nanodisk.Higher-order subradiant hybrid modes(EH13δ and EH14δ) are excited by manipulating the disk radius,and multiple Fano resonance arise in spectra.It’s worth noting that these optical responces are not dependent on a retardation effect,and strong Fano resonances are genearated even for a very thin disk.Beside,one can get similar results in a single dielectric triangle,square,or rectangle nanopaltes and so on.The simple geometry and high structural symmetry make these dielectric nanoparticles promising for practical implementions in biosensing and optoelectronic.