Fano resonance in silver nanoparticles in SOI structure: design of plasmonic nano switch

In this paper we investigate potential of plasmonic nano switch as a result of Fano-resonance observed in periodically arrayed silver (Ag) nanoparticles embedded over silicon (Si) on insulator (SOI) substrate, by using 3D finite difference time domain (FDTD) method. Structural parameters of the embedded silver nanoparticles were optimized giving rise to plasmon modes in the device. We find that as the device is scanned for a range of wavelength varying from visible to near infra-red, the transmission spectra exhibits Fano-line shape asymmetry for input wavelength regime near 1.3 - 1.55micron, whereas normal resonating peak is observed in the visible region. The optical properties of the switch reveal, enhancement in transmission due to strong plasmonic Fano resonance between the background and resonant processes. Sharp Fano-resonance, specific to interacting quantum systems, is exhibited by the proposed embedded hybrid design of metal nanorods into Si, which meets the condition required for high contrast switches and hence can be exploited as per anticipated results. Fano resonance in this nanorod-substrate system can also be used for designing nanoantennae, lasers, sensors, SERS etc.