Tellurite And Fluorotellurite Glasses For Active And Passive

2. Literature review; MDO 41
scattering due to microinhomogeneities is proportional to 1/λ 2 ). A0 is a constant [41-44],
which depends on local variations in electron density, refractive index, and composition,
frozen in from the melt. A0 will be defined in the next section in relation to tellurite
glasses. Raman and Brillouin scattering result from optical and acoustic phonons causing
density perturbations, which inelastically scatter incident photons [35].
Loss in an optical fibre can be calculated by the ratio of the intensity of the light
leaving the fibre, It, to the intensity entering the fibre, Ii, over length ∆l, measured in m.
Loss (dB.m -1 ⎛ I
10log
⎜ 10
I
) = −
⎝
∆l
t
i
⎞
⎟
⎠
(2.9)
The benefit of a logarithmic scale is that losses from different sources are additive [35]. A
loss of 0.1 dB.m -1 corresponds to 98 % transmission over 1 m, 1 dB.m -1 to 79 %, 10
dB.m -1 to 10 %, 20 dB.m -1 to 1 %, etc. Fig. (2.7) illustrates this relationship.