Modal characteristics and the tunability of horizontal hybrid gap plasmonic waveguide

We propose and numerically investigate the modal characteristics of tunable horizontal hybrid gap plasmonic (HGP) waveguides at the optical communication wavelength of 1.55 μm. The HGP waveguides consist of a metal wedge coupled with a dielectric waveguide via an air gap in the horizontal direction. We obtain a long propagation length (at centimeter scale) in these HPG waveguides while maintaining the propagation mode size at a deep-subwavelength scale (λ2/104). The tunable mechanisms for the HGP waveguides are analyzed in detail. We also propose a liquid-based tunable HGP waveguide and analyze the tunable characteristics of this device in detail. The simulation results indicate that the proposed tunable HGP waveguides have a high potential for applications in reconfigurable plasmonic devices and lab-on-a-chip systems.