Optics and Photonics Society of Iran

In this paper, a periodic array of Silver spherical-nanoparticles is considered to act as a tunable plasmonic filter in telecommunication window, in which, the array is embedded by a layer of Germanium and set on the silicon dioxide substrate. The purpose of this material configuration is to increase the local fiend between adjacent nanoparticle and Ge layer which in turn increases the absorption of optical fields by nanoparticles in array. Illumination at infrared region excites localized surface plasmons (LSPRs) of silver nanoparticles and due to the hybridization between these nanoparticles in array, the resonance frequency LSPRs red-shifts to telecommunication window. Coupling between LSPRs and incident field leads to confining optical field at the gap distance between nanoparticles and improves the quality of filtering at telecommunication window in the terms of optical absorption at the wavelength of interest. Finite difference time domain (FDTD) method have been used to both calculate filtering spectra and local field between adjacent nanoparticles. Also, the effect of size parameters of nanoparticles on quality of optical confinement and filtering spectra have been studied.