Local Field Enhancement in Infrared Graphene- Dielectric Hyperbolic Slot Waveguides

In this letter, we propose graphene-dielectric hyperbolic slot waveguides and investigate the local field enhancement in the slot region at infrared frequencies. The modal performance as well as field enhancement are analyzed through numerical simulations based on multilayer structures, effective medium theory, and coupled slab waveguide modeling. It is found that the electric field amplitude in the slot can be enhanced by nearly 20 times in magnitude with 70% of the power flow confined in the slot region. This exceeds previously reported silver-germanium as well as silicon-based slot waveguides. In stark contrast to the traditional waveguide-based devices, higher field enhancement with smaller modal attenuation could be achieved simultaneously through lower frequency or higher chemical potential, larger graphene filling factor, or larger period number. These graphene-dielectric hyperbolic slot waveguides may find applications in biosensors and infrared spectroscopy.