Novel Optical Effects In Metallic And Graphene Plasmonic Structures

Metallic and graphene plasmonic micro-nano structures possess wide application prospects in photonics and optoelectronics because of their capability of localizing and manipulating light in sub-wavelength scale.In this thesis,we studied the novel optical effects of metallic optical antennas and graphene planar chiral structures.The main works of this thesis are as follows:1、We studied the optical responses of arrays of asymmetric plasmonic gap antennas.The resonance properties can be controlled by the asymmetry.Quality factors more than 30 are achieved,and an enhancement of the electric field exceeding 40 times is predicted to be obtained in antennas at the resonance in the near-infrared range.Furthermore,similar designs can be applied in the THz range,and even higher quality factors and stronger field enhancements can be realized.The combination of Fano resonances with gap effects of metallic nanostructures provides an effective way for improvement in light trapping and field enhancement.2、We studied asymmetric transmission of circularly polarized waves through a nanostructured planar chiral graphene film in THz range.And the relative enantiomeric difference of monatomic layer graphene in the total transmission varies with the change of graphene’s Fermi level.The plasmonic excitation in the graphene nanostructure is the enantiomerically sensitive.This phenomenon will deepen our understanding light-matter interactions in planar chiral structures.3、We designed a type of reflective circular polarizer based on the asymmetric transmission effect of graphene planar chiral period structures.Due to enantiomerically sensitive excitation of surface plasmons,one of the incident circularly polarized light will be reflected while the other will be totally absorbed.The extinction ratio reaches more than 50 at the resonance wavelength.