White Papers

PM Double-Clad Fibers for High-Power Lasers and Amplifiers

January 28, 2003

By: Kanishka Tankala, Adrian Carter, David Machewirth, Julia Farroni, Jaroslaw Abramczyk, and Upendra Manyam

Fibers for high-power laser and amplifier applications require large claddings with high numerical apertures for efficiently coupling pump energy. In addition, such fibers should have high rare-earth dopant concentrations in relatively large cores, with low numerical apertures, to reduce non-linearities. Furthermore, polarization maintaining double-clad fibers (PM-DCF) are needed for coherently combining the outputs of several lasers/amplifiers to achieve output powers in excess of 100 kW for military and industrial laser applications. In this paper, we report the progress made towards fabricating PM double-clad fibers, with a variety of fiber characteristics, to facilitate development and production of high-power lasers and amplifiers. In particular, a Panda-type PM-DCF with a 0.06 NA, 30 micron diameter, Yb-doped core is reported. We also discuss various criteria that are critical for designing these PM double clad fibers.