Specialty Optical Fibers Handbook

shown by Poulsen et al. [40] that in fibers having a highly UV-sensitive core,

the transverse UV absorption allows coupling to asymmetric cladding modes,

even in the absence of a blaze angle during grating writing. Their model empha-

sizes that the index asymmetry, due to the UV light absorption, can explain

the strength of the first cladding mode dip that cannot be explained by an

unintentionally induced blaze angle.

9.6 RARE EARTH-DOPED PHOTOSENSITIVE FIBERS

The RED photosensitive fiber is an important component for the develop-

ment and fabrication of fiber laser cavities. Unfortunately, most RED fibers are

not photosensitive because of the replacement ...