A Stripe-Assisted Hybrid Plasmonic Waveguide for the Propagation of Terahertz Waves

Using finite-element method, we investigated a hybrid plasmonic terahertz waveguide with an additional stripe with a frequency of about f = 3 THz. The structure consisted of a semiconductor stripe located at the center of the gap between a five-layer graphene and a high-index dielectric ridge which were all placed on a low-index dielectric substrate. A properly sized stripe helps the power ratio inside the gap to considerably increase, and the normalized mode area to improve greatly as well. A power confinement ratio of 0.65 and a normalized mode area of 0.03 were obtained. This shows respective improvements of 30% and 72% in comparison with conventional waveguides. This structure also provides a good propagation length of ~820 μm.