3.1 Fiber Attenuation
99
ultraviolet absorption are shown in Fig. 3.3. Because E is inversely proportional
to the wavelength λ, ultraviolet absorption decays exponentially with increasing
wavelength. In particular, the ultraviolet loss contribution in dB/km at any wavelength
(given in μm) can be expressed empirically (derived from observation or experiment)
as a function of the mole fraction x of GeO 2 as [5]
α uv =
154.2x
46.6x + 60
× 10
−2 exp
4.63
λ
.
(3.5)
Example 3.3 Consider two silica fibers that are doped with x = 6% and 18% mole
fractions of GeO 2 , respectively. Compare the ultraviolet absorptions at wavelengths
of 0.7 μm and 1.3 μm.
Solution Using Eq. (3.5) for the ultraviolet absorption, then
(a) For the fiber with x = 0.06 and λ = 0.7 μm
Fig. 3.3 Optical fiber attenuation characteristics and their limiting mechanisms for a GeO 2 -doped
low-loss low-water-content silica fiber
99
ultraviolet absorption are shown in Fig. 3.3. Because E is inversely proportional
to the wavelength λ, ultraviolet absorption decays exponentially with increasing
wavelength. In particular, the ultraviolet loss contribution in dB/km at any wavelength
(given in μm) can be expressed empirically (derived from observation or experiment)
as a function of the mole fraction x of GeO 2 as [5]
α uv =
154.2x
46.6x + 60
× 10
−2 exp
4.63
λ
.
(3.5)
Example 3.3 Consider two silica fibers that are doped with x = 6% and 18% mole
fractions of GeO 2 , respectively. Compare the ultraviolet absorptions at wavelengths
of 0.7 μm and 1.3 μm.
Solution Using Eq. (3.5) for the ultraviolet absorption, then
(a) For the fiber with x = 0.06 and λ = 0.7 μm
Fig. 3.3 Optical fiber attenuation characteristics and their limiting mechanisms for a GeO 2 -doped
low-loss low-water-content silica fiber