Enhanced near-infrared transmission through periodic H-shaped arrays

We report experimental observation of enhanced near infrared transmission through periodic H-shaped arrays in metallic thin films. A broad transmission band centered at about 1.6 μm is found and the transmission coefficient can be as high as about 16.3% for an arm width of 120 nm for the H-pattern. The position of the transmission peak shifts to a short wavelength by about 140 nm when the arm width is increased to 200 nm. This variation feature is inverse to that found in periodic hole arrays. It indicates that the localized surface plasmon is an important parameter contributing to the enhanced transmission. The H-shaped arrays exhibit a strong polarization effect consistent with the geometry anisotropy. Numerical simulations by using a transfer matrix method reproduce quite well the obtained transmission spectrum.