The excitation of surface-plasmon-polariton (SPP) waves guided by a columnar thin film (CTF) deposited on a one-dimensional metallic surface-relief grating was studied employing the rigorous coupled-wave approach, when the grating plane, the plane of incidence, and the morphologically significant plane of the CTF are all different. The incident plane wave in this grating-coupled configuration could be either por s-polarized. The absorptance was plotted against the polar angle of incidence at a fixed value of the free-space wavelength and absorptance peaks were correlated with the solution of the dispersion equation of the underlying canonical boundary-value problem for SPP waves. Both p-polarized and s-polarized plane waves can excite SPP waves, provided that either the plane of incidence and/or the morphologically significant plane of the CTF do not coincide with the grating plane. None, one, or multiple SPP-wave excitations are possible, depending on the orientations of the grating plane and the morphologically significant plane with respect to the plane of incidence. The direction of propagation of an SPP wave thus excited may not wholly lie in the plane of incidence.

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The excitation of a surface-plasmon-polariton (SPP) wave guided by a columnar thin film (CTF) deposited on a one-dimensional metallic surface-relief grating was investigated for sensing the refractive index of a fluid infiltrating that CTF. The Bruggemann homogenization formalism was used to determine the relative permittivity scalars of the CTF infiltrated by the fluid. Change in the refractive index of the fluid was sensed by determining the change in the incidence angle for which an SPP wave was excited on illumination by a p-polarized plane wave, when the plane of incidence was taken to coincide with the grating plane but not with the morphologically significant plane of the CTF. Multiple excitations of the same SPP wave were found to be possible, depending on the refractive index of the fluid, which can help increase the reliability of results by sensing the same fluid with more than one excitations of the SPP wave.

Grating-coupled excitation of surface plasmon-polariton waves guided by the interface of a metal and an anisotropic dielectric material evinces morphological effects arising from the divergence of structural anisotropy (grating) from constitutive anisotropy (dielectric material). Even if the metal is replaced by an isotropic dielectric material, the same effects are seen in the excitation of Dyakonov surface waves. The morphological effects vanish with constitutive anisotropy, as exemplified with a columnar thin film (CTF) as the dielectric material. Both p-polarized and s-polarized incident plane waves can excite the surface plasmon-polariton (SPP) waves as well as Dyakonov surface waves, provided that either the plane of incidence and/or the morphologically significant plane of the CTF do not coincide with the grating plane.

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