Investigation Of The Optical Properties Of Subwavelength Metallic Grating By Boundary Element Methods

Since the phenomena of extraordinary transmission when light wave through arrays of sub-wavelength apertures on a piece of metallic film has been reported, more and more scientists have been interested in the optical phenomena, optical elements with sub-wavelength metallic grating structure and their rich underlying physics mechanism. In order to reveal the physics mechanism of extraordinary transmission, scientists studied on the slit structure at first, because the slit structure is the most typical structure in various aperture structures. And in 2003, Ebbesen et al. also pointed out the relations between the characteristics of extraordinary transmission and the geometry structure parameter of the metal film. So more and more scientists pay their attentions on the reason why the geometry parameter of the metal film can affect the characteristic of extraordinary transmission. This thesis is based on rigorous electromagnetic field theory and the boundary conditions of electromagnetic fields, and we study the interaction between the various structure of the single sub-wavelength metallic slit and the characteristic of extraordinary transmission. Furthermore, we study the interaction between the single aperture surrounded by periodic corrugations and the characteristic of extraordinary transmission to analyze the characteristics of optics about the sub-wavelength metallic grating. The main conclusions of this paper contain:[1] We propose the revised boundary integral method (RBIM) that combines the boundary integral method (BIM) and the boundary element method (BEM) together. In this paper, we found the BIM is faster than BEM, but BEM is preciser than BIM, so we can use their advantage to improve the two methods.[2] Study the relation between the symmetrical characteristic of the infinite structure sub-wavelength metallic slit and the characteristic of extraordinary transmission. We found there are two transmission peaks in the range of 480-750nm to any geometry structure slits. However, there is different influence about the transmission to different geometry structure slits. The transmittivity of the slits with etch structure is about twice of the slits without etch structure.[3] Study the characteristic of the optical of the sub-wavelength metallic grating. We study the relation between the periodicity, symmetry of the sub-wavelength metallic grating and the characteristic of the optical. It implies that the equivalent refractive index method doesn't adapt to analyze the sub-wavelength metallic structure.