Reduced loss of plasmon propagation in a Ag nanowire on Si substrate

Abstract

The energy loss of surface plasmon polaritons (SPPs) propagating in metal nanostructures has been a bottleneck to their practical applications in integrated photonics devices at subwavelength scale. In this work, we find that, using thick Ag nanowires (NWs) on Si, propagation loss can be prominently reduced. The propagation length is about twice larger than that on SiO2/Si substrates. And the Si substrate exhibits the minimum energy loss among the three types of commonly used substrate (Si, SiO2/Si and glass). We attribute the mechanism to the enhanced hybridization and mode splitting resulted from the stronger interaction between the nanowire plasmon and Si substrate, which can further reduce the ohmic loss and energy radiation into the substrate. Our findings demonstrate the advantages of Si substrate in supporting higher order plasmon modes, which are crucial for the integration with Si-based electronic circuits and devices.