Polarization Characters Of Extraordinary Optical Transmission In Subwavelength-Structured Metallic Films

Since its discovery in 1998, the phenomenon of extraordinary optical transmission has aroused a worldwide enthusiasm to research on its physics mechanism and its application. This work emphasizes on the study of the polarization and filter characters of extraordinary optical transmission through periodic and fractal subwavelength hole array in metal films.Classical coupled-wave theory is used to analyze the coupling process between light and the surface plasmons wave on metal films with hole array. The analysis shows clearly the physical mechanism of extraordinary optical transmission is that the SPPs plays the main roll in this process. The calculation demonstrates that, instead of energy flux directly passing through the holes, the electromagnetic modes could exchange energy by overlapping the evanescent fields under the assistance of hole array. The periodicity of the array provides the momentum-matching condition to present the transmission peaks.Utilizing the anisotropic transmission of rectangular hole array achieving polarization-manipulated dual band transmission. It is theoretically proved by FDTD that anisotropic transmission exists and the main influential factor is the hole width not the period and aspect ratio. Dual band filter focusing 532 nm green light and 632 nm red light is achieved both theoretically and experimentally. The polarization controlled dual wavelength (532 nm and 632 nm) is also achieved by using dual rectangular hole array. Researches show that using these dual band and dual wavelength filters can achieve red-green light switch, its meaning is that just controlling incidence polarization the wavelength can be manipulated. This character is hard to achieve by ordinary optical appliances and poses applications for new type polarization-manipulated dual band transmission optical appliances for fluorescence analysis.This work also pay attention to the subwavelength fractal slits perforated on metal film. The first experimental achievement of subwavelength fractal pattern's dual band transmission in infra-red region is achieved. Its polarization-controlled dual band transmission in infrared region, the peak distinction and extinction ratio show superiority to ordinary rectangular hole array.The fractal slits has polarization-manipulated dual band transmission in infrared region. Theoretical design of fractal pattern aligning infrared region with dual band at 1.15μm and 1.35μm is achieved. The merit is that its oblique incidence wavelength invariance and high energy contraction in oblique incidence condition. This feature can ensure that under large oblique incidence case most of light energy is conserved. This subwavelength fractal metal film is well suited for infrared polarization-controlled dual band antenna especially the infrared optical communication appliances.Filtering of Extraordinary optical transmission on subwavelength metal film is also studied. Careful study is focused on circular holes array. Using finite-different time-domain (FDTD), the optimized transmission spectra centering RGB color are obtained. Experimental confirmations of these optimized results are achieved, featuring purity, oblique incidence invariance and high transmission. This color filter is well suited for OLED display, its interpretability and conductivity are suited for substituting OLED electrode and improving its light extraction at the same time.