Propagation properties of a surface plasmonic waveguide with double elliptical metallic nanorods

Abstract

We introduce a kind of surface plasmonic waveguide with double elliptical metallic nanorods. The dependence of the distribution of longitudinal energy flux density, the effective index and the propagation length of the fundamental mode with longer propagation length supported by this waveguide, on the geometrical parameters and the working wavelengths are analysed using the finite-difference frequency-domain （FDFD） method. Results show that the longitudinal energy flux density is distributed mainly in the middle area, which are formed by two elliptical metallic nanorods, and the longitudinal energy flux density is stronger closer to the arc sides of the metallic nanorods. The effective index and propagation length of the fundamental mode can be adjusted by the centric distance of two ellipses as well as the size of the two semiaxis. At a certain working wavelength, relative to the case of a=b, in the case of ab, the size of the contact area of field and metallic surface is large, the interaction of field and silver is weak, the effective index becomes small, so the propagation length becomes large. With certain geometric parameters, relative to the case of λ=7050 nm, in the case of larger λ, the area of field distribution is large, the size of the contact area of field and metallic surface is also large, the interaction of field and silver is weak, the effective index becomes small, so the propagation length becomes large. This kind of metallic surface plasmonic waveguide can be applied to the field of photonic device integration and sensors.