Metal Subwavelength Holes Array Model For Adjustment And Transmission Characteristics Of The Study

Ebbesen et al first experimentally observed extraordinary optical transmission (EOT) of subwavelength hole arrays on metal films, whose potential application values in optical equipment, such as color filters, sensors and photolithography, aroused widespread concern. As both the Kirchhoff diffraction theory and the Bethe theory could not explain EOT phenomenon, scholars were researching for its hidden mechanism theoretically and experimentally, and proposed several theoretical models.Aiming for difficulties of explaining EOT phenomenon of2D subwavelength hole arrays by surface plasmon polariton(SPP) model, a3D finite-difference-time-domain (FDTD) method was utilized to study EOT phenomenon deeply. A great distinction between the results derived from normal FDTD method and the experimental results was found, which limited the application of FDTD on EOT of hole arrays.For this reason, the simulation structure was modified and the interface parameters were properly selected and set so that the influence of the air-medium interface could be eliminated and the shape of transmission peaks were greatly improved, thus the effect of relevant interfaces on optical transmission could be clearly reflected by FDTD. The new FDTD model was further utilized to study transmission properties of metal subwavelength hole arrays of unsymmetrical periods, different incident angles, actual hole structures and under different dielectric conditions. It was found that the behaviors of corresponding transmission peaks were different with various positions and filling ratios of dielectric and then a true (1,1)SPP mode was observed. During the simulation research, it was also found that the errors due to actual hole manufacturing would cause opposite polarities inside and outside a hole which led to position shifts of corresponding transmission peaks and valleys. As the periodic phase match condition on which traditional SPP model was dependent did not consider the influence of the phase difference of Ez inside and outside a hole on the transmission peaks and valleys, the discovery of the phase difference made up the deficiency that traditional SPP model failed in explaining the position shifts of transmission peaks with different hole radius and shapes. Degiron once used LSP to explain the effect of the hole shape on transmission of hole arrays, and it is considered in this assay that the minimization of the phase difference of Ez inside and outside a hole is one of the formation conditions of LSP. The above research further broadens the knowledge on EOT phenomenon, and remedies the limitation of existing theories, which can help to guide relevant application of the phenomenon in actual apparatus.