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, photos ensitive clad, and wide-depressed cladding fibers under varying gratin g azimuthal asymmetry conditions. Fibers with narrow-depressed claddin gs are found to have lo,ver cladding mode losses for small degrees of asymmetry than previously proposed fiber designs for cladding-mode red uction.