  A Core/Cladding Yb-doped fiber amplifier configuration is presented that
relies on anti-Stokes fluorescence cooling for effective heat mitigation in
high-power operation. In the proposed design, the inner cladding of the double
clad fiber is doped with the same ion as in the core; therefore, the excess
heat generated from the background absorption is removed by the anti-Stokes
fluorescence in both core and inner cladding. We consider both silica and ZBLAN
glasses for the host material in the Core/Cladding Yb-doped fiber amplifier.
The model incorporates the spatial profiles of the signal and pump intensities,
as well as the amplified spontaneous emission. The total linear heat density
and temperature distribution in the fiber amplifier are calculated. The results
show that the anti-Stokes fluorescence cooling in the Core/Cladding Yb-doped
configuration can mitigate the generated heat effectively in high-power
operation, which obviates the need for an external cooling system.
