Scattering from nonuniform tilted fiber gratings

Using volume current analysis, we describe the scattering from intracore fiber gratings with various nonuniformities and find that effects of cross-sectional and longitudinal variations can be roughly decoupled. We show that cross-sectional asymmetry affects the azimuthal pattern of scattering around the fiber and find good agreement with real gratings exhibiting UV-induced grating asymmetry across the core. We also show that longitudinal variations affect the spread of scatter angles with respect to the fiber axis, and this angular spread depends on the Fourier transform of the profiles of the grating period, the average index, and the index modulation of the grating.