Optically active surface polaritons

Abstract

A new wave-vector-space method of finding electromagnetic wave propagation in bounded media without use of boundary conditions is applied to finding surface polaritons on an optically active anaxial crystal. Because a proper constitutive derivation of the optical-activity tensor shows that the quadrupolar interaction plays an important role, the continuity of the tangential component of the H field is no longer a valid boundary condition. In its absence the use of the wave-vector-space method that uses no boundary conditions is essential. Another unique aspect of the wave-vector-space method is that it derives a surface-nonlocality tensor that accounts for the altered nonlocal interaction of optical activity near the surface. The dispersion relation of the surface polariton is found to be independent of both the bulk optical-activity parameter and the surface-nonlocality parameters. The electric field profile is dependent on the bulk optical-activity parameter to first order. This dependence causes the surface polariton to lose the TM-mode character that it has in a nonoptically active crystal. Surprisingly, the surface-nonlocality parameters also disappear from the field profile to first order. This complete disappearance to first order of the nonlocality parameters is a surprising and physically unexplained result because it does not happen in the transmission and reflection problem or in the optically active waveguide problem.