Title :
Experimental Comparison of Fundamental Mode Content in Er:Yb-Codoped LMA Fibers With Multifilament- and Pedestal-Design Cores
Author :
Kuhn, Vincent ; Unger, Sonja ; Jetschke, Sylvia ; Kracht, Dietmar ; Neumann, Jörg ; Kirchhof, Johannes ; Wessels, Peter
Author_Institution :
Laser Zentrum Hannover e.V., Hannover, Germany
Abstract :
We report on fundamental mode content measurements performed on single-frequency large mode area fiber amplifiers based on Er:Yb-codoped multifilament-core (MFC) and step-index pedestal-design fibers. The mode content of the amplifier output was analyzed with respect to free-space TEM modes using a nonconfocal scanning ring cavity. At power levels of several watts, the commercial step-index pedestal-design fibers with respective core diameters of 23 and 25 m showed a mode content exceeding 80%. However, a mode content of up to 95% could be obtained with an MFC fiber also with larger core diameter of 31/28 m in hexagonal shape. To the best of our knowledge, we utilized the nonconfocal scanning ring cavity technique for the first time in the wavelength region of 1.5 m and additionally for the first time on fibers with pedestal as well as MFC design.
Keywords :
laser cavity resonators; laser modes; optical design techniques; optical fibre amplifiers; ring lasers; JkJk:Er,Yb; MFC fiber; free-space TEM modes; fundamental mode content measurements; multifilament-core fibers; nonconfocal scanning ring cavity; single-frequency large mode area fiber amplifiers; size 23 mum; size 25 mum; size 28 mum; size 31 mum; step-index pedestal-design fibers; wavelength 1.5 mum; Cavity resonators; Fiber lasers; Laser beams; Materials; Optical fiber amplifiers; Optical fiber polarization; Optical fiber theory; Laser beams; optical fiber amplifiers; optical fiber measurements; optical fiber testing;
Journal_Title :
Lightwave Technology, Journal of
DOI :
10.1109/JLT.2010.2088378
