Enhanced Optical Transmission and Sensing of a Thin Metal Film Perforated with a Compound Subwavelength Circular Hole Array

We propose and numerically investigate the optical transmission behaviors of a sub-wavelength metal film perforated with a two-dimensional square array of compound circular holes. Enhanced optical transmission is obtained by using the finite-difference time-domain (FDTD) method, which can be mainly attributed to the excitation and coupling of localized surface plasmon resonances (LSPRs) and surface plasmon polaritons (SPPs), and Fano Resonances. The red-shift of the transmission peak can be achieved by enlarging the size and number of small holes, the environmental dielectric constant. These indicate that the proposed structure has potential applications in integrated optoelectronic devices such as plasmonic filters and sensors.