A visible-near infrared tunable waveguide based on plasmonic gold nanoshell

A tunable plasmonic waveguide via gold nanoshells immerged in a silica base is proposed and simulated by using the finite difference time-domain (FDTD) method. For waveguides based on near-field coupling, transmission frequencies can be tuned in a wide region from 660 to 900\,nm in wavelength by varying shell thicknesses. After exploring the steady distributions of electric fields in these waveguides, we find that their decay lengths are about 5.948--12.83\,dB/1000\,nm, which is superior to the decay length (8.947\,dB/1000\,nm) of a gold nanosphere plasmonic waveguide. These excellent tunability and transmittability are mainly due to the unique hollow structure. These gold nanoshell waveguides should be fabricated in laboratory.