The Study Of Surface Wave In Extraordinary Transmission Phenomenon Of Sub-wavelength Metallic Optical Device

Since 1998, the extraordinary optical transmission (EOT) phenomena when light transmits through sub-wavelength hole arrays on a metallic film is reported by Ebbesen et al. There has been great interest from scientists in the research underlying physics mechanism and novel application of EOT phenomena. At present, there is not a clearly conclusion of the reason about this phenomena. Surface plasmon polaritions were introduced to explain the anomalously high transmission by Ebbesen who found this phenomena at first. Later, other interpretations, based on 'dynamical diffraction' in periodic slit and hole arrays or various kinds of resonant cavity modes in one-dimensional (1D) slits and slit arrays, have also been proposed. Reassessment of the earlier data by new numerical studies and new measurements has prompted a sharp downward revision of the enhanced transmission factor from ₁,000 to ₁0, and has motivated the development of a new model of surface wave excitation, namely the composite diffracted evanescent wave (CDEW) model. Until now, there is no a certain conclusion for the fantastic optical phenomenon. In 2006 international authority periodical《Nature physics》has three papers(vol.2. P₂₆₂～P₂₆₇, April.2006; P₅₀₉～P₅₁₀, August.2006; P₅₅₁～P₅₅₆, August.2006) to discuss the physical mechanism of EOT phenomena. In 2007 international authority periodical《Nature》has one paper(vol.446. P₅₁₇～P₅₂₁, 27.March.2007) to report that the periodic metallic arrays can produce EOT. There is also one paper (vol.452. P₇₂₈～P₇₃₁,10.April.2008) in《Nature》to give a microcosmic explanation about EOT in 2008. Because the hole structure of metallic film is the most simple and typical structure of slit, it may reveal the physical mechanism of the optical phenomena. This thesis is based on rigorous electromagnetic field theory, and we start form Maxwell's equations and the boundary conditions of electromagnetic field. Then we apply the Boundary Element Method(BEM) to simulate the optical transmission phenomena and the feature of the light intensity distribution of the boundary. At last we fit and analyze the light intensity distribution. The details are as follows:1. Because the methods(BEM, boundary element method, BIM, boundary integral method) have their disadvantages, we propose a revised method, BLEM, boundary linear element method. It can be used to calculate on the simple size or fine section boundary. 2. We investigate the surface wave feature in a slit structured by two metallic films and there a groove in each film when the incoming lightγ=808nm is inserted. By fitting and analyzing the light intensity distribution, we gain some waves whose wave-length near the resonance wave. And we find some surface waves or SPPs on the groove structure. Those surface waves evanesce to the both sides from the slit structure and groove structure.