The effect on the Bragg-grating-induced cladding-mode coupling of varying the extent of the photosensitive region in a step-index fiber is analyzed. We introduce a figure of merit for the suppression of cladding-mode loss and compare different matched cladding fiber designs. It is found to be advantageous to increase the extent of the photosensitive region. However, no significant improvement is obtained by extending the photosensitive region more than approximately 10 mu m into the cladding. This result is not in agreement with a simple analysis that neglects UV absorption, which suggests that the radius of the photosensitive region should be close to twice as large. (C) 2000 Academic Press.
Nielsen, M. L., Berendt, M. O., Bjarklev, A. O., & Dyndgaard, M. G. (2000). Design of Matched Cladding Fiber with UV-sensitive Cladding for Minimization of Claddingmode Losses in Fiber Bragg Gratings. Optical Fiber Technology, 6(1), 49-60. https://doi.org/10.1006/ofte.1999.0309