Tunable transmission at 100 THz through a metallic hole array with a varying hole channel shape.

Extraordinary optical transmission spectrum for a two-dimensional metallic hole array (2D-MHA) changes with the hole channel shape. In this paper a new converging-diverging channel (CDC) shape is proposed. A three-dimensional (3D) finite element method is utilized to analyze the transmission characteristics of the 2D-MHA with CDC. The transmission peaks are blue-shifted when the gap at the throat of CDC is reduced. Similar blue-shift in the transmission peaks are observed for a straight channel MHA when the aperture size is reduced. The transmission for the straight channel MHA is not sensitive to the metal film thickness. But, for a CDC MHA the transmission varies with the metal film thickness. Also, the CDC shape gives an extra degree of geometrical variable to 2D-MHA for tuning the transmission peak location with potential applications in nanolithography, imaging and biosensing.