Narrowband absorber based on magnetic dipole resonances in two-dimensional metal-dielectric grating for sensing

摘要

In this paper, we propose a two-dimensional metal-dielectric grating with dielectric nanoarrays on a thin gold film structure for refractive index sensing due to its near unity absorption at 1050 nm wavelength. Perfect absorption can be achieved due to the horizontal magnetic dipole coupling the free-space incident waves into surface plasmon-polaritons (SPPs). The effect of the geometrical parameters on the absorption spectra and sensing performance are studied. The preferred results show that the corresponding figure of merit is calculated to be 73.1 RIU-1, which shows a remarkable improvement than the previous reported sensors. Moreover, it also demonstrates excellent performance by measuring the light intensity change in the reflected light at a certain wavelength, which provides the possibility for low cost and portable detection.