Extraordinary Optical Transmission In Subwavelength-structured Fractal Metallic Films

Since it was discovered in1998, the phenomenon of extraordinaryoptical transmission (EOT) had drawn many scholars’ attention. In recentyears, with the further development of nano science and technology,researchers have been able to achieve processing technology in nanometerscale, which makes them get more interest on the EOT of special structuresin nanostructure metallic films. The research on optical transmissionmechanism and application of this abnormal phenomenon in metallic filmhas become a hot point in the field of scientific research for these years.In this article, beginning from the Maxwell equations, we introducedthe basic principle of this abnormal phenomenon of light transmission andits application in the fields of scientific research. Using the classical coupledwave theory, we analyzed and proved that the abnormal phenomena of lighttransmission mechanism mainly result from the coupling interaction of theincident light and the surface Plasmon wave. In this process, the periodichole arrays in metallic film provide a necessary phase matching conditionfor transmission enhancement. We first studied the extraordinary optical transmission on the Kochsnowflake fractal slit structure, Cross Fractal array structure and rectangularSierpinski-Carpet aperture array in metallic film in this paper, from variousaspects such as the film thickness, the period, the incident angle and thepolarization state. We used the finite difference time domain (FDTD)method in theory calculation and the simulation results are in goodagreement with the experiments. These novel structures probably will begreat useful for the researches on novel photonic devices.