| Surface plasmon polaritons (SPPs) are electromagnetic waves that propagate along metal-insulator interface and formed by the interference between electrons at the surface of metal film and the photons. Optical devices with SPPs applied in can break the traditional optical diffraction limit, realize the integration of microelectronics and photons in the same chip. In recent researches, it is found that when incident light irradiate onto the periodic subwavelength hole array, light transmittance is considerably higher than the percentage of the pore area with film area at specific wavelength. This phenomenon is called extraordinary optical transmission. Broadband enhanced transmission in tunable optical filter, high density data storage and near field optical field has extensive practical significance. Enhanced transmission phenomenon of the subwavelength periodic metal slit wedge structure is studied in this paper with finite element method (FEM). The main research content is as follows:(1) The effects of structure parameters of slit wedge on broadband enhance transmission characteristics are studied. The influence of moving the wedge incident port to the right and changing parameters of the slit structure on broadband transmission characteristics are also systematically researched. The results show that the transmittance is obviously enhanced when the incident port of the metal slit remains upright.(2) In addition, the periodic concave slot metal slit structure are designed to achieve broadband transmission. Changing the internal parameters of the structure and the thickness of the metal film influence the transmission characteristics of concave slot array. The results show that the transmission characteristics is mainly depended on structure parameters.These results have important guiding significance in designing micro-nano devices and near-field optical components with broadband enhanced transmission capacity. |
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