High power fiber end-cap with 6 kW output power

High power fiber end-cap is an essential component for kW-level fiber lasers, the key technique of which is the splicing of fiber end-caps with low loss and high tension strength. Due to the huge difference of the diameters of fiber and large-size end-cap, the splicing of them cannot be realized by traditional fusion splicers. A fiber end-cap splicing system is designed and built. The splicing art is implemented for different size end-caps with good tension strength. Output power with 3.01 kW is realized with a single-mode fiber end-cap while only heating up by 7 ℃/kW without active cooling. Output power with 6.08 kW is realized with a multi-mode fiber end-cap while only heating up by 6 ℃/kW without active cooling.