A new long-range single nanotube hybrid plasmonic waveguide

In this paper, a novel long-range single nanotube hybrid plasmonic waveguide composed of a silicon nanotube and a thin metal layer embedded in it is designed. The geometry of this waveguide is much different from the conventional hybrid plasmonic waveguide such as a tube-wedge or rectangle long-range hybrid plasmonic waveguide. With strong coupling between the silicon nanowire mode and long-range surface plasmon polariton (SPP) mode, both deep subwavelength mode confinement and low propagation loss has been achieved. We evaluate the properties of the ultra-small hybrid plasmonic waveguide including propagation length (L), normalized mode area (A_eff /A0), and figure of merit (FoM). The results show that the designed hybrid plasmonic waveguide enables an ultra-small deep-subwavelength mode in a smaller area than presented long-range hybrid SPP waveguides. What’s more, the propagation length is longer than 1mm and optimization FoM of our waveguide is much larger than 10⁴, which show much better performance that of wedge or rectangle hybrid plasmonic waveguide. Finally, another significant improvement of our structure is that the area of the cross-section is about 0.05um², which is much smaller than any other presented hybrid plasmonic waveguides.