Preparation Of Periodic Metal / Medium Structure And Its Optical Properties

The periodically perforated metal/dielectrics (MDs) structures have many unusual optical properties, such as extraordinary optical transmission (EOT), antenna directivity and negative refractive index (NRI). Nano MDs structure has become one of the hottest research topics of micro-and nano-optics for its promising applications in infrared and visible optics region.In this thesis, researches have been done on EOT and antenna directivity of MDs. Bow-tie and aperture arrays are fabricated. Optical properties of all samples are studied both experimentally and numerically.The main contents of the thesis are described as follows:1. Bow-tie array of MD multilayer nanoparticles are obtained on glass substrate by using nano-sphere lithography and thermal evaporation. The optical properties are studied both experimentally and theoretically. The transmission dip located at optical region is successfully observed. The central position of the transmission dip will shift to shorter wavelength (blue shift) with the increasing of the numbers of the MD layer. COMSOL Multiphysics is used to investigate the bow-tie optical antenna effects. When the electric dipole is located near the bow-tie, its intensity and radiation directivity of the far-field radiation patterns will be enhanced by the bow-tie nano particles.2. Large-scale periodic metallic aperture arrays are experimentally fabricated by method of optical lithography. We experimentally find that all the samples have two transmission bands in mid-infrared region. The two transmission bands will redshift when the diameter or lattice constant of the aperture array increase. Simulations by COMSOL indicate that the frequency corresponding to the strongest radiation intensity matches the central position of the transmission bands, because of the cooperation between surface plasmon polaritons (SPPs) and localized surface pslasmon (LSPs). 3. Transmissions of Metal/Dielectric/Metal sandwiched structures are calculated by COMSOL. Two transmission peaks due to EOT are observed. The retrieved effective material parameters suggest that the NRI occurs at the longer wavelength peak. The NRI’s central frequency will move to longer wavelength when the diameter increases, while move to the longer wavelength when the lattice constant increases.