Propagation Properties of a Surface Plasmonic Waveguide with double elliptical air cores

We introduce a kind of surface plasmonic waveguide with double elliptical air cores. The dependence of distribution of longitudinal energy flux density, effective index and propagation length of the fundamental mode supported by this waveguide on geometrical parameters and working wavelengths are analyzed using the finite-difference frequency-domain (FDFD) method. Results show that the longitudinal energy flux density distributes mainly in the two wedged corners which are formed by two elliptical air cores, and the closer to the corners the stronger the longitudinal energy flux density. 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 the certain working wavelength, relative to the case of a =b in the case of a >b the energy in the metal is small, then the interaction of field and silver is weak, and the effective index becomes small, and the propagation length becomes large. With certain geometric parameters, relative to the case of lambda = 632.8nm, in the case of larger lambda, the area of field distribution is large, and the energy in the metal is small, then the interaction of field and silver is weak, and the effective index becomes small, and the propagation length becomes large. This kind of hollow surface plasmonic waveguide can be applied to the field of photonic device integration and sensors. (C) 2008 Optical Society of America.