Magnetic Plasmon Propagation Along a Chain of Connected Subwavelength Resonators at Infrared Frequencies

A one-dimensional magnetic plasmon propagating in a linear chain of single split ring resonators is proposed. The subwavelength size resonators interact mainly through exchange of conduction current, resulting in stronger coupling as compared to the corresponding magneto-inductive interaction. Finite-difference time-domain simulations in conjunction with a developed analytical theory show that efficient energy transfer with signal attenuation of less then $0.57\mathrm{dB}/\mu \mathrm{m}$ and group velocity higher than $1/4c$ can be achieved. The proposed novel mechanism of energy transport in the nanoscale has potential applications in subwavelength transmission lines for a wide range of integrated optical devices.

Figure 1

Schematic illustration of a single split ring resonator (a) and a connected unit for implementation in subwavelength sized MP transmission lines (b). The geometrical characteristics and position of the dipole source excitation are included.

Figure 2

(a) The magnetic field amplitude $|H_z|$ detected at the center of the resonators is plotted vs excitation frequency. Frequency split $\Delta {\omega }_{1,2}$ is observed for the case of two physically connected SSRRs (solid line). The local current distributions are calculated for the (b) antisymmetric and (c) symmetric MP modes.

Figure 3

(a) FDTD simulation of a MP propagation along a connected chain of 50-SSRRs at $\hslash \omega =0.3\mathrm{eV}$; (b) dispersion $\omega (k)$, and (c) attenuation coefficient $\alpha (\omega )$. The analytical result [Eq. (6)] including conduction current and magneto-inductive interactions, black solid curve, matches well with the FDTD numerical data (circle dots) The predicted MP characteristics based singularly on exchange current interactions (${\kappa }_2=0$) or magneto-inductive interactions (${\kappa }_1=0$) are presented with dashed and dotted curved lines, respectively.