Surface plasmon–polariton wave propagation guided by a metal slab in a sculpturednematic thin film

Abstract

Surface plasmon–polariton (SPP) wave propagation guided by a metal slab in a periodicallynonhomogeneous sculptured nematic thin film (SNTF) was studied theoretically.The morphologically significant planes of the SNTF on both sides of the metalslab could either be aligned or twisted with respect to each other. The canonicalboundary-value problem was formulated, solved for SPP wave propagation, andexamined to determine the effect of slab thickness on the multiplicity and the spatialprofiles of SPP waves. Decrease in slab thickness was found to result in moreintense coupling of two metal/SNTF interfaces. But when the metal slab becomesthicker, the coupling between the two interfaces reduces and eventually SPP waveslocalize to one of the two metal/SNTF interfaces. The greater the coupling betweenthe two metal/SNTF interfaces, the smaller is the phase speed. Both the phasespeed and the attenuation of an SPP wave also depend on the twist between themorphologically significant planes of the SNTF on the two sides of the metal slab.