
the Al/Ge counter-graded SMF, we have implemented this core profile design in the
making of the Yb-doped, SBS-managed LMA double-clad all-glass fibers.
Characteristics of SBS- Managed LMA Double-Clad Fibers
The SBS-managed, Yb-doped double-clad fiber has been successfully made by imple-
menting the Al/Ge counter-graded core composition design, schematically shown in
Figure 15.34 as described earlier. To validate the SBS improvement in the LMA fiber,
one other fiber was also made with a standard step-index profile using only germania
as the dopant. The properties of the two fibers are summarized in Table 15.5.
Both fibers had a 30-mmdiametercore,a3