Investigation On The Resonant Phenomena In Subwavelength Microstructures And The Design Of Functional Devices

Since the first time extraordinary optical transmission (EOT) phenomenon was demonstrated by T.W. Ebbesen et al. in1998, manipulation of light at the nanoscale with metamaterial has captivated increasing attention in recent fifteen years owing to its potential application in optical filter, nanoscale sensing, subwavelength optical waveguides etc. Besides, lots of resonant phenomena in nanoscaled metal-dielectric hybrid structures are far from full understanding even for simple structures. Consequently, in this thesis, we devote ourself to the investigation of resonant phenomena supported in nanoscaled metal-dielectric hybrid structures, especial for some kinds of easy overlooked, however, representative hybrid structures. The main results are listed below:Firstly, we presented rigorous derivations of the transfer matrix method (TMM) for one-dimensional metal-dielectric hybrid nanostructures, and rigorous coupled wave analysis (RCWA) method for two-dimensional metal-dielectric hybrid nanostructures. Basing on these methods, we programmed MATLAB codes applicable for calculating the diffractions of light by any one-dimensional and two-dimensional nanostructures. Besides, we gave a zero-order propagation mode approach for calculating the diffraction of light by a simple subwavelength metallic grating with narrow slits. With this approach, semi-analytical expressions can be obtained for the total reflectance and transmittance, which is a useful and quantitative method to analyze the resonant phenomena in two-dimensional nanostructures.Secondly, we proposed a multilayered metal-dielectric nanostructure for transparent conductor, which is one of the most exciting palsmonic devices basing on nanostructures nowadays. The proposed structure contains a seamless silver film, sandwiched between two sets of Si-SiO2-Si substructures. The supported resonant modes can make the seamless metallic film nearly transparent (T>90%) from visible to near infrared. Meanwhile, the sheet resistance of the whole structure is as small as2Ω/sq. Those excellent performances: broadband high transmission, polarization weak dependence, stable for a large range of incident angles, tiny sheet resistance and structure’s simplicity, make it a promising candidate for transparent conductor or panel display. Another kind of popular functional device-narrowband absorber is also investigated. We proposed a four layered stacked nanostructure that can achieve perfect narrowband absorption not only in visible spectrum regime, but also in THz spectrum region. The absorbance is nearly unity (-99%), and the bandwidth is less than1%with respect to the central frequency. This is the best solution for ultra-narrowband optical and THz absorber as far as we know. As for ultrabroadband absorption devices, we proposed a multi-periods one dimensional metamaterial with unit cell Si-SiO2-Si-Ni that can achieve much high absorption (A>90%) from0.5μm to2.5μm. Moreover, the broadband absorption is nearly independent of the polarization and incident angle of the light, which should be a good candidate for absorbing material.Thirdly, we systematically investigated the diffraction effects in some kinds of easy overlooked, however, representative hybrid structures basing on two-dimensional metallic-dielectric nanostructures, including:(1) hybrid grating structure containing two kinds of one-dimensional representatives units:slits and grooves;(2) single layered metallic grating in asymmetric surroundings;(3) metallic grating and dielectric slabs hybrid structures;(4) double layered metallic grating structure and (5) six layer metal-dielectric hybrid grating structure. We found some new resonant phenomena in these representative hybrid structures, and proposed some applications basing on the resonances, such as broadband polarizer, bandpass filter, narrowband absorbers and broadband absorbers, etc.