Narrow-depressed cladding fiber design for minimization of cladding mode losses in azimuthally asymmetric fiber Bragg gratings

The cladding and radiation mode loss characteristics of photo-induced gratings written in fibers with a narrow-depressed inner cladding are compared to the properties of gratings written in matched clad, photosensitive clad, and wide-depressed cladding fibers under varying grating azimuthal asymmetry conditions. Fibers with narrow-depressed claddings are found to have lower cladding mode losses for small degrees of asymmetry than previously proposed fiber designs for cladding-mode reduction.