Stable and Efficient Coupling of High-Power Continuous-Wave Laser With Uncooled Anti-Resonant Hollow-Core Fibers With End Caps

Hollow-core fibers provide an ideal environment for the interaction of a laser and gases; however, achieving stable and efficient coupling of a high-power laser is one of the key problems to be solved. Here, we study stable and efficient coupling of a high-power continuous-wave fiber laser with anti-resonant hollow-core fibers spliced with end caps. By optimizing the splicing process, a maximum laser power of 460 W was injected and 356.5 W was outputted under uncooled conditions, realizing a total transmission efficiency of approximately 77.5%. A test of more than 1 h showed the stability of this a coupling method. A few other important characteristics, such as the Fresnel reflection of the end caps and the influence of the end caps on the transmission beam quality, were measured and examined. This study opens new opportunities for stable and highly efficient coupling of high-power lasers with hollow-core fibers, which is significant for their applications in many other fields besides high-power fiber gas lasers, such as high-power laser delivery and liquid lasers in hollow-core fibers.