SURFACE-POLARITONS IN CYLINDRICAL OPTICAL FIBERS

The properties of the polariton modes associated with a resonance in the dielectric function of an optical fiber are derived. Particular attention is given to the surface polaritons, whose energy densities and power flows are concentrated close to the interface of the fiber core and its cladding. The results are illustrated with a range of dispersion curves for the two most important cases, when the fiber dielectric function has the reststrahl and plasma forms. General expressions are given and illustrated graphically for the power flow and power density. It is shown numerically that the energy velocity, or group velocity, can have opposite sign to the phase velocity of the surface polariton.