Enabling Single-Mode (SM) operation in Large-Mode-Area (LMA) fiber amplifiers and lasers is critical, since a SM output ensures high beam quality and excellent pointing stability. In this paper, we demonstrate and test a new design approach for achieving SM LMA rod fibers by using a photonic bandgap structure. The structure allows resonant coupling of higher-order modes from the core and acts as a spatially Distributed Mode Filter (DMF). With this approach, we demonstrate passive SM performance in an only ~50cm long and straight ytterbium-doped rod fiber. The amplifier has a mode field diameter of ∼59Lim at 1064nm and exhibits a pump absorption of 27dB/m at 976nm. © 2011 Optical Society of America.
Bibliographical noteThis paper was published in Optics Express and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org.globalproxy.cvt.dk/abstract.cfm?URI=oe-19-8-7398. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.
- Microstructured fibers
- Fiber optics
- Lasers, fiber