The Role of Periodicity in Enhanced Transmission through Subwavelength Hole Arrays

Two kinds of subwavelength hole arrays in metallic films are designed in order to verify the important role of the periodicity in enhanced transmission of light. The samples were fabricated by focused ion beam(FIB). In both structures, the hole diameter d are kept the same: d=220nm.The measured optical spectra show that the quasiperiodic hole arrays exhibit an enhanced transmission peak centered at 707nm with a transmission intensity of about 20%, while no plasmon resonance peak is found for the amorphous hole arrays. These phenomena indicate the important role of the long-range structural order (in particular, the periodicity) in assisting the coupling of incident light wave with the surface plasmon modes of the metallic structures.