Researches On Manipulation Of Optical Properties In Subwavelength Metallic Materials And Low-dimensional Nanostructures

Subwavelength metallic materials are currently investigated intensively on manyfields including condensed matter physics and near fields optics, since they show intrigu-ing physics and potential application in many aspects. SPPs play a vital role in manyoptical phenomena on the subwavelenth dimensions, which make it enrich our knowl-edge about interactions between light and subwavelength metallic materials to study SPPspropagation behavior and related manipulation methods. At the same time, these investi-gations will promote the advance about the new generation of nanophotonic devices andall-optical circuits. By using the finite difference time domain (FDTD) method, this dis-sertation introduce a series of works on SPPs's propagation law and some methods tomanipulate them, as well as related optical properties for subwavelength metallic mate-rials and structures. On the other hand, the modification of optical properties in semi-conductor superlattices with structure defects is discussed by using the effective massiveapproximation. The main results are summarized as follows:A wide bandgap plasmonic Bragg re?ector was proposed by changing the slit wide ofmetal-insulator-metal (MIM) waveguide and inserting dielectrics with high index. Whenchanging one of the thickness, the defect were introduced for this periodic structures, theresonant electromagnetic mode appear in the photonic band gap (PBG). Moreover, wefound this localized mode coupled poorer with the enlargement of PBG. Furthermore,the multiple PBG plasmonic Bragg re?ector was suggested, where three MIM waveguidewere included into every cell. Our numerical calculation verified SPPs can form morephotonic band gaps in this structures. Also, the width of PBG can be modified by changingthe slit width of MIM waveguide, which may be helpful to design the related nanophotoicdevices.SPPs phase resonance on the compound subwavelength hole arrays were investi-gated. It is found that phase match condition is broken when the symmetry of complexunit cell is destroyed, resulting in the transmission decrease suddenly at certain wave-length, namely the SPPs phase resonance. For the compound subwavelength hole arrayscomposed of identical square holes, the phase difference for SPPs are mainly governed bythe symmetry of complex unit cell, which leads to the degeneracy of transmission spectravary with the geometrical arrangement of this compound subwavelength hole arrays.A method was proposed that the transmission spectra of compound subwavelength arrays of rectangular hole can be modified by the filled dielectric alternately in a com-pound unit cell. The simulated results exhibit that the transmission for compound holearrays of rectangular holes with grater contrast of effective refractive, can not be affectedremarkably by the arrangement style or the symmetry of complex unit cell. However, thetransmission spectra may be modified at some extent by the interspace between holes forthe rectangular holes with low contrast of effective refractive. Only when the transmis-sion peak corresponding to LSP combines with SPPs resonance together, the variation ofsymmetry for complex unit cell makes its degeneracy be modified. These results showthat the transmission for compound arrays of rectangular holes can be manipulated bythe filled dielectric within the holes and/or the arrangement of compound unit cell, whichchanges the cutoff wavelength, leading to the variation of the excitation efficiency of LSPand its coupling behavior. These studies provide new knowledge about the interactionsbetween light and compound periodic metallic nanostructures.The effects of defect layers and constituent layers thickness on optical transition insemiconductor superlattice with structural defect were demonstrated, including transitionfrom localized electronics states to other localized electronic states, delocalized scatteringelectronic states. Our calculation displayed these transition probabilities are sensitiveto the defect layers and the nearest constituent layer thickness. Moreover, when theselayers thickness are altered, the variation tendency for transition probabilities between twolocalized states are governed by the parity of minband gap index n. However, transitionprobabilities between localized states and delocalized transition are not related to n.