Enhanced coupling efficiency between dielectric and hybrid plasmonic waveguides

Abstract

The modal distributions and properties of dielectric and hybrid plasmonic (HP) waveguides are investigated systematically. Their coupling efficiency through a direct coupling scheme is estimated by numerical simulation and the results are compared with values predicted by the Fresnel formula. The influence of various factors on the coupling efficiency between dielectric and HP waveguides, including interface scattering, absorption caused by light coupling to the surface plasmon polariton mode, and the mismatch between the two waveguide modes, is analyzed theoretically. A tapered coupling structure with linearly varying height and width of the silicon layer is proposed, with which extremely high coupling efficiency (94.4%) and good broadband coupling performance (above 90%) are demonstrated. © 2013 Optical Society of America.