Radiation modes and tilted fiber gratings

Scattering from tilted fiber gratings into free space is useful in various filtering and monitoring applications. We develop a waveguide-scattering analysis based on the coupled-mode theory and new sets of radiation modes that resemble the HE and EH guided modes of an optical fiber. By simplifying the calculation of modal coupling coefficients and the scattered field, this approach allows us to verify the results from free-space perturbation models such as the volume-current method. The HE and EH radiation modes defined here are suitable for scattering analysis of cylindrical waveguides in general. (c) 2006 Optical Society of America.