A Hybrid Plasmonic Waveguide for the Propagation of Surface Plasmon Polariton at 1.55 μm on SOI Substrate

A hybrid plasmonic waveguide (HPW) has been numerically investigated, based on silicon-on-insulator (SOI) structure near the telecom wavelength λ = 1550 nm using the finite-element method. The HPW consists of metal cap placed on SOI rib, which has a trench with a semicircle interface at the bottom of the trench. With the proper choice of waveguide sizes, our proposed HPW can support hybrid long-range surface plasmon which have strong mode confinement A_eff/A₀ ≅ 0.0035-0.035 and long propagation length (L_eff > 525 μm) simultaneously. In addition, for the proposed HPW, the calculated coupling length for two parallel identical waveguides which is separated by distance d = 250 nm is approximately 1.3 μm, which is very helpful in realizing photonic integration circuits with ultrahigh integration density.