Evolution of surface-plasmon-polariton and Dyakonov-Tamm waves with the   ambichirality of a partnering dielectric material
  The planar interface of an isotropic homogeneous metal and an ambichiral dielectric material can guide surface-plasmon-polariton waves. The planar interface of an isotropic, homogeneous dielectric material and an ambichiral dielectric material can guide Dyakonov-Tamm waves. In either instance, we found that, as the ambichiral partnering material evolves into a finely chiral material, the solutions of the dispersion equation for surface-wave propagation evince convergence. The convergence is faster for the surface waves with larger phase speeds than for the surface waves with smaller phase speeds. 
Muhammad Faryad and Akhlesh Lakhtakia
physics.optics