Plasmons in a spatially modulated quasi-one-dimensional quantum wire

We consider a quasi-one-dimensional superlattice consisting of a quantum wire, the equilibrium carrier density of which is spatially modulated along its length. We apply a simple hydrodynamic model for the collective excitations of low-dimensional inhomogeneous systems to calculate the plasmon dispersion relation of the periodic heterostructure. As expected, the acoustic plasmon of the homogeneous quantum wire is folded into the first Brillouin zone due to the modulation and acquires optical branches. Gaps open at the zone boundary due to Bragg scattering, but unlike the two-dimensional and three-dimensional cases, no gap opens at the zone center for the modulated wire. © 1996 The American Physical Society.