Strong Resonance and Terahertz Wave Transmission Enhancement of Low-Porosity Metal Hole Array with Bow-Tie-Shaped Apertures
Metallic plates with arrays of subwavelength apertures appear to have several resonances due to coupling with incident electromagnetic waves. In the terahertz wave range, a sensing method using these structures has already been proposed. In order to study structures to obtain high sensitivity, we fabricated a metallic structure with bow-tie-shaped apertures and measured its transmission properties. The transmission peak frequency was at lower frequencies than the resonance frequency decided by its lattice shape, and depended strongly on the aperture shape. We observed very high transmission efficiency and strong resonance of the structure when the shape resonance corresponded to the lattice resonance.
Abstract A layer of random defects in the simple cubic Ising model with nearest neighbor ferromagnetic interactions of strength J is considered. Using the real space renormalization group method we calculate defect free energy in the whole temperature range. Specifically, we analyze: the layer of diluted defects, the layer of spin-glass type defects, and the layer of mixed defects. The free energy is strongly dependent on the value of couplings between the defect and the bulk.