  Surface phonon polaritons hold much potential for subwavelength control and
manipulation of light at the infrared to terahertz wavelengths. Here, aided by
monochromatic scanning transmission electron microscopy - electron energy loss
spectroscopy technique, we study the excitation of optical phonon modes in SiC
nanorods. Surface phonon polaritons are modulated by the geometry and size of
SiC nanorods. In particular, we study the dispersion relation, spatial
dependence and geometry and size effects of surface phonon polaritons. These
experimental results are in agreement with dielectric response theory and
numerical simulation. Providing critical information for manipulating light in
polar dielectrics, these findings should be useful for design of novel
nanoscale phonon-photonic devices.
