Multiple trains of same-color surface-plasmon-polaritons guided by the planar interface of a metal and a sculptured nematic thin film. Part VI: Spin and orbital angular momentums

The spin and the orbital parts of the angular momentum of multiple surface-plasmonpolariton (SPP) waves guided by the planar interface of a metal and a periodically nonhomogeneous sculptured nematic thin film (SNTF) were theoretically investigated. Both the Minkowski and Abraham formulations of angular momentum were considered. Multiple SPP waves guided by the metal/SNTF interface propagating along a direction that does not lie wholly in the morphologically significant plane of the SNTF were found to have different magnitudes and directions of the spin and the orbital parts of the angular momentum. The spin angular momentum is oriented in a variety of directions, but the orbital angular momentum is perpendicular to the direction of propagation and lies in the interface plane. Not only does the periodic nonhomogeneity of the partnering dielectric material engender a multiplicity of SPP waves, but also it can enhance the magnitudes of the spin and orbital parts of their angular momentums.