Fuseless side-pump combiner for efficient fluoride-based double-clad fiber pumping

Abstract

We report a novel technique for side-pumping fluoridebased double clad fibers allowing a record coupling efficiency of 93 % and a maximum power handling near 100 W at 981 nm. Our simple technique is based on wrapping a silica taper around a fluoride fiber and therefore does not require any complex fusion between these two dissimilar fibers. Under passive cooling, pump combiners made of undoped and erbium-doped fluoride fibers were successfully operated during several hours at respective incident powers of 91 W and 44 W. Heat management issues and active cooling strategies are also discussed. This innovative combiner is a keystone towards the development of compact and robust highpower mid infrared fiber lasers and amplifiers.