| Surface plasmons (SPs) play a very important role in the interactions of light and metallic micro-nano structures. In this thesis, we explore a new strategy to prepare a novel plasmonic-photonic microstructure based on self-assembly of dielectric colloidal microspheres, and we study the interesting optical properties and their tunibilities of these metallodielectric, which stems from the coupled hybrid modes of plasmon resonant modes and the optical modes, leading to enhanced optical transmission phenomena and perfect optical absorption.Making an optical opaque metal film transparent has attracted great attention because of its perceived potential applications in areas of optics and photonics. Recently, optical properties of planar metallic film coated with periodically corrugated dielectric layers have been studied in depth. In this topic, optical transmissions through a continuous planar metal film (without holes) with two-dimensional (2D) colloidal crystals coated on one or both interfaces have been experimentally and numerically investigated. Enhanced optical transmissions in the near-infrared regime can be observed for the metal film with identical 2D colloidal crystals coated on both sides, which occur due to the resonant tunneling of surface polariton Bloch eigenmodes excited on periodically structured interfaces. Numerical simulations of transmission spectra show an excellent agreement with the measured ones. Additionally, the numerical simulations reveal that the intensity of tunneling transmission is strongly dependent on the relative shift of the 2D colloidal crystals on the opposite interfaces of the metallic film. It is the first time to demonstrate experimentally the extraordinary optical transmission of a metallic film coated symmetrically with periodically dielectric patterns, especially in the wavelength regime of visible and near-infrared, and our work also elucidates further the plasmon-photon interactions in nano-coated metallic films. Clearly, by changing the parameters of the microspheres such as their sizes, refractive index and lattice structure as well, these optical modes can be tuned, and the huge enhancement of transmission at these optical modes suggests this microstructure has the potential applications in photonic devices.Due to the huge potential applications in areas such as solar energy and photovoltaic detection, management of light absorption has been the focus of research. In this topic, we have studied the optical properties of composite metallodielectric microstructures, which is fabricated by self-assembly 2D colloidal crystal on the opaque gold film on the substrate, followed by deposition of gold half-shell on the each colloid. We find that this microstructure exist a series of coupled hybrid modes of plasmon resonant modes bound at metal-dielectric interface and the optical modes localized in the dielectric colloidal crystal, which cause a high absorption of the incident light. However, this high absorption appears as a narrow band of absorption spectrum. Then, by the introduction of disorder in the periodic monolayer of microspheres, we obtain a relatively broad absorption band led by the localized plasmonic and photonic modes of single elements of this random plasmonic-photonic microstructure and their hybrid or blending modes as well. In order to further broaden the absorption band, we propose a new method by mixed two different sizes of colloidal microspheres self-assembled in certain proportions which result in a ultrabroad bandwidth, wide angle and the polarization-independent near-infrared absorber. The optical features of such a absorber could be easily scaled proportionally with the diameter of the colloidal microspheres. We believe that this low-cost, easily prepared microstructure can have a very large application in optoelectronic detection, absorption of solar energy and so on. |
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