Page 65 - Fiber Bragg Gratings

44 Chapter 2 Photosensitivity and Photosensitization of Optical Fibers

Figure 2.14: Comparison of time-averaged growth rate of the UV-induced
refractive index change for different fibers compared to cold H 2-soaked:B-Ge fiber
on the right column. Maximum index change recorded for the H-BGe codoped
3
fiber was 6.76 X 10~ . The UV source was a quadrupled diode pumped QS Nd:YLF
laser operating at 262 nm with 60-mW writing power and used with a phase
mask. This is a direct comparison of the induced index change in Type I gratings
showing the sensitivity to UV radiation (adapted from Ref. [40]).

normalized to the fastest fiber: the H 2: BGe, which writes an 87% reflec-
tive, 1.5-mm long grating in 10 seconds.

References

1 Kleinmann D. A., "Nonlinear dielectric polarization in optical media," Phys.
Rev. 126(6), 1977-1979 (1962).
2 Kazansky P. G., Russell P. St. J., and Takebe H.,"Glass fiber poling and appli-
cations," Lightwave Technol. 15(8), 1484-1493 (1997).
3 Griscom D. L., "Optical properties and structure of defects and structure of
defects in silica glass," Ceramic Soc. Jap. 99(10), 923-942 (1991).
4 Neustruev V. B., "Colour centres in germanosilicate glass and optical fibers,"
J. Phys. Condens. Matter 6, 6901-6936 (1994).