Engineering the phase speed of surface-plasmon wave at the planar interface of a metal and a chiral sculptured thin film

The solution of a boundary-value problem formulated for a modified Kretschmann configuration shows that the phase speed of a surface-plasmon wave guided by the planar interface of a sufficiently thin metal film and a chiral sculptured thin film (STF) depends on the vapor incidence angle used while fabricating the chiral STF by physical vapor depoistion. Therefore, it may be possible to engineer the phase speed quite simply by selecting an appropriate value of the vapor deposition angle (in addition to the metal and the evaporant species).