Comparisons of two subwavelength aperture arrays with different lattice structure for light transmission

The transmission through subwavelength square and hexagonal lattice structure hole arrays in aluminum films at mid-infrared spectral range is reported experimentally in this work. Enhanced transmission peak is observed at wavelengths up to seven times of the hole's diameter. Positions of the transmission peaks are coincide with the prediction of surface plasmon polaritons (SPPs) theory. Lattice structure is proved to be a decisive factor of the transmission spectra. Interface media on both sides of the metal structure also affect the transmission peak position. These results are meaningful for the aperture applications in infrared detection and frequency selective surfaces devices.