Thermal resilience of polymer-coated double-clad fiber

Description/Abstract

Following the advance of ytterbium-doped fiber laser to kW-level cw-output power, there is a particular interest in using shorter fiber length with large cores since they mitigate detrimental nonlinear effect such as stimulated Raman and Brillouin scattering. However, most of the fibers lasers used currently are coated with a low-index polymer to guide the pump light. This is a simple and effective solution. These polymer coatings impede the extraction of the heat deposited in the doped region in the laser cycle because their thermal conductivity is an order of magnitude lower than that of fused silica. Therefore, the record power extraction per unit length has been held by all-glass rod-type fiber laser at about 250-300 W/m