Raman scattering from the upper and lower modes of surface phonon polaritons in ZnTe

The upper and lower modes of surface phonon polaritons have been observed in free-standing thin slabs (～7 μm) of single-crystal ZnTe by a conventional Raman-scattering technique at room temperature. The experimental dispersion relations were measured in various scattering angles (outside the sample) from 0.9° to 2.0° and agree with the theoretical dispersion relations. The main factors enabling us to observe the two surface modes are the appropriate selections of the material with a small attenuation factor for surface phonon polaritons and of the thickness of the sample slabs.