Abstract
Utilizing normal mode analysis of Maxwell's equations and finite-difference-time-domain simulations we find extraordinary optical transmission in nanoarrays of insulating coaxial cylindrical rings embedded in metal films. As the rings become narrower we find transmission peaks at longer wavelengths, with the peak wavelength increasing indefinitely as the rings narrow. This behavior results from the excitation of cylindrical surface plasmon resonant modes on the cylindrical insulator-metal interfaces of the rings. These findings indicate that the excitation of cylindrical surface plasmons in these structures can produce propagating modes and enhanced transmission at wavelengths longer than those predicted previously.