High-power testing of CO2-laser spliced fiber arrays

High power delivery via fibers and scaling the power level through arrays of fibers is an emerging topic for many fields of high power applications. Monolithic fiber connections to end caps, already known from free-space to fiber coupling of kW of optical power, can be expanded to 1D or even 2D fiber arrays, using a CO2-laser to splice each fiber sequential to an end cap substrate. As the CO2 laser radiation melts the glass locally at its surface, it realizes a monolithic glass-to-glass transition between the fiber and the end cap, enabling kW levels of power transmission through this interface without catastrophic damage. We report about high power testing of 1D and 2D fiber arrays, spliced sequentially to an Infrasil^® endcap, and connected to up to 2 kW of optical power per fiber for damage testing. The splicing platform is Nyfors’ Smart-Splicer™, an axicon-based system that produces a ring-shaped CO<inf>2</inf> laser focus, enabling the splicing of single- or multimode fibers to a substrate with pitches down to 250 µm in 1D, and <1 mm in 2D arrays and a lateral positioning tolerance <<10 µm.