The Plasmon Oscillations In The Asymmetric Nanostructures And The Induction Of Transparency

Plamson is reffered as collective oscillations of electrons on the metallic surface as the interaction between metal and incident light in essence. The interaction between two and more micro-structure can give rise to interesting mutiple plasmonic modes, which can be utilized to tune resonance frequency of system. As the materials science is developed, the merging of plasmonics and materials have led to the achievement of controlling modes by a light field, which may open up a new perspective towards nanophotonics, and contributes to control of light in nanoscale dimension. Plasmonics modes can be modulated in frequency domain by varying symmetry of complex structrue, and achieved the controlling of light in nanoscale dimension.In this paper, the main research results are as follows:1 Localized surface plasmon resonances and its coupling-theory is introduced. The absorption property of single symmetrical nanoshell or asymmetrical nanoshell is studied, as well as the effect of the offset on resonance modes of nanoshell dimer. The energy level of nanoshell dimer can be adjusted by varying symmetry, and the mechanism of energy level is described by using the schematic of plasmon hybridization.2 The plasmon hybridization in a nanoring with symmetry-broken is investigated by using finite element method (FEM) under the different polarization of incident light (along x and y). The result shows that it can give rise to higher order modes by varying the symmetry of structure. The plasmon hybridization is investigated within a nanoring by reference the plasmon hybridization in nanoshell.3 A nanorods trimer of gold is designed. The absorption spectra and plasmon induced transparency (PIT) is investigated in a nanorods trimer of gold, and physical explanation on mechanism of PIT is proposed. The physical process of PIT is described by using two modified linearly coupled Lorentzian oscillators.4 Based on nanorods trimer, the physical mechanism of plasmon induced transparency (PIT) is investigated in detail. It has been found that the absorption of the trimer shows the tunable property as a function of symmetry. The PIT of trimer originates from the coulping between the vertical nanorod and parallel double nanorods, and depends on the symmetry of parallel double nanorods. According to the obtained result, a novel physical interpretation is proposed, namely, that the PIT stems from the coherent superposition between split modes of dipole bright mode of the vertical nanorod. Plasmon induced transparency windows can be adjusted by changing symmetry of parallel double nanorods.