GUIDED ACOUSTIC PHONONS IN QUANTUM WIRES - THEORY OF PHONON FIBER

Acoustic phonon modes confined to a GaAs cylindrical quantum wire within AlAs are analytically investigated within the context of an elastic continuum model. Elastic properties are assumed to be isotropic for both materials for mathematical convenience. The displacement vector is expressed by the scalar potential and two vector potentials. The confined acoustic phonon modes are classified into three types according to the rotational symmetry of the potential functions: dilatational, torsional, and flexural modes. Dispersion curves of the modes show phonon subband structures with finite cutoff frequencies due to confinement of wave, in lateral directions. The density of the confined phonon modes accordingly appears as staircaselike structures.