Surface polaritons in a circularly cylindrical interface: Surface plasmons

Abstract

A theoretical investigation of surface polaritons in the circularly cylindrical geometry is presented. The complete set of Maxwell's equations (retardation effects are not neglected) is solved with the simple dielectric function, $\epsilon \left(\omega \right)=1-\frac{{\omega }_p^2}{{\omega }^2}$, where ${\omega }_p$ is the bulk plasma frequency. The resulting transcendental equation for the eigenfrequencies is solved via numerical methods for three representative values of the cylindricality constant, $\alpha =\frac{{\omega }_{p}a}{c}$, where $a$ is the cylinder radius and $c$ the velocity of light. In addition to the real nonradiative surface plasmons, various virtual radiative surface plasmons exist with properties depending rather strongly on $\alpha$. The results are compared with existing experimental data. Further experiments are proposed in order to reveal the most interesting features of the surface plasma modes.