A Manipulated Extraordinary Optical Transmission Filter Composed with Subwavelength Hole Complex Arrays

We present a new style extraordinary optical transmission (EOT) nano optical filter combined by two kinds of subwavelength holes array on a gold film. In the design, a square array of non-penetrating holes (hollow holes) inlays into another square array of penetrating holes ordered by a central arrange mode. We numerically calculated the transmission spectra of the patterned gold films by finite-difference time-domain (FDTD) method. Results show that the transmission of the filter can be manipulated by changing the depth of non-penetrating holes. The (1, 1) peak can be enhanced when the incident light normally illuminates one side of the filter with the hollow holes, yet the (1, 1) peak can be suppressed when the light illuminates the other side without hollow holes. It also depicts that the hollow hole array results in energy level splitting of (1, 0) mode propagating on the surface of the filter. What’s more, the splitting can be eliminated by modulating the depth of the hollow holes. Our study further reveals the role of suface plasmon effect in the EOT.