Abstract
A subwavelength hole array, which consists of a thin metallic film and a dielectric, enables to transmit a certain wavelength caused by surface plasmon polaritons (SPPs). SPPs exist at the interface between the metal and the dielectric, which means that the transmission spectrum strongly depends on the propagation of SPPs across the material interface. SPPs propagation is influenced by the array periodicity and hole shape. The relationship between the periodicity and the transmission spectra can be obtained from a band diagram of the energy and wavenumber of the SPPs. However, determining the hole shape that will provide a desired transmission spectra is difficult. For the systematic design of hole shape, a level set method based on topological optimization can be used to perform an accurate electromagnetic analysis. In the level set method, the material interface is clearly defined using a finite element mesh. Therefore, the physical properties of the boundary interface can be calculated precisely. By comparing experimental and simulated results, we confirmed that the proposed method is effective for the systematic design of hole shape.
