Au/SiO₂ Nanoring Plasmon Waveguides at Optical Communication Band

We design and investigate plasmon waveguides based on linear arrays of Au nanorings in an SiO2host for use in an optical communication band (lambda ~ 1550 nm). Nanoring particles have better tunability and can achieve more laterally compact waveguides, compared to their solid counterparts, such as nanospheres and nanodisks. Three-dimensional simulations employing the finite-difference time-domain algorithm are used to determine the set of geometrical parameters attaining localized surface plasmon resonance at 1550 nm. It is found out that, in the SiO2host, Au nanorings attain LSPR at 1550 nm with a 175-nm inner diameter, a 35-nm height, and a 30-nm thickness. It is shown that linear chains of Au nanorings can transport the electromagnetic energy at 1550 nm, with transmission losses gammaT= 3 dB/655 nm and gammaL= 3 dB/443 nm and group velocities nugT= 0.177c0and nugL= 0.327c0for transverse and longitudinal polarizations, respectively, where c0is the speed of light in a vacuum.