A polarization-maintaining Yb-doped large mode area fiber with depressed-index inner cladding layer and confinement of rare-earth dopants has been drawn as a long tapered fiber. The larger end features a core/clad diameter of 56/400 μm and core NA ~ 0.07, thus leading to an effective mode area over 1000 μm². The fiber was tested up to 100 W average power, with near diffraction-limited output as the beam quality M² was measured < 1.2. As effective single-mode guidance is enforced in the first section due to enhanced bending loss, subsequent adiabatic transition of the mode field in the taper section preserves single-mode amplification towards the larger end of the fiber.

Date Published: 22 February 2017
PDF: 6 pages
Proc. SPIE 10083, Fiber Lasers XIV: Technology and Systems, 1008314 (22 February 2017); doi: 10.1117/12.2250864

Published in SPIE Proceedings Vol. 10083:
Fiber Lasers XIV: Technology and Systems
Craig A. Robin; Ingmar Hartl, Editor(s)