Highly efficient and stable coupling of kilowatt-level continuous wave laser into hollow-core fibers

Abstract

Fiber gas lasers based on gas-filled hollow-core fibers (HCFs) perfectly combine the advantages of fiber lasers and gas lasers and have obtained fast development in the past years. However, stable and efficient coupling of high-power pump lasers into the HCFs is one of the key problems to be solved. In this paper, we study the coupling of high-power continuous wave fiber lasers into anti-resonant HCFs through an end-cap. By optimizing the splicing parameters, a maximum laser power of 1167 W was injected into the 1-m-long HCFs, and 1021 W was obtained at the output end, giving a total transmission efficiency of ∼87.5%. A more than 1 h test showed the stability of such a coupling method. Meanwhile, the laser beam quality was well maintained. This work opens new opportunities for stable and highly efficient coupling of high-power lasers into HCFs, which is significant for its applications in many other fields besides high-power fiber gas lasers, such as high-power laser delivering.

Functional Fibers and Functional Fiber-Based Components for High-Power Lasers

“…Their latest research demonstrated an efficiency of 90.4% and the CW delivery of 50 W with a stable and alignment-free all-fiber laser setup [378]. The newest result reported by Cui et al obtained a highly efficient and stable launching into AR-HCF with the maximum transmission power reaching 1021 W through splicing the AR-HCF with a fiber endcap [382], the experimental setup can be found in Fig. 7e.…”

“…AR-HCF is one of the most popular microstructure fibers according to the emerging results reported recently. High-power pulse delivery employing AR-HCFs has been a well-known topic, it appears that researchers are turning more and more attention to its CW delivery applications [371][372][373][374][375][376][377][378][379][380][381][382][383].…”

“…e Highly efficient coupling of kilowatt-level CW laser into AR-HCF through splicing the fiber with an end-cap; Reproduced with permission from Ref. [382], Copyright 2022, Chinese Laser Press 383], as shown in Fig. 7d.…”

“…Typically, the function of both the CT-FBGs and LP-FBGs is to convert the core-guided light at unwanted Raman 1st-Stokes wavelength to the cladding-light and then strip it out to suppress the SRS effect. The CT-FBG evolves from the predecessor of tilted FBG under the chirp modulation [385,386,[382][383][384][385][386][387][388][389][390], which is inscribed in large-mode-area fibers by using the side-writing technique with phase masks. Through the writing process, the phase mask rotates to generate a specific tilted angle, as shown in Fig.…”

A 110 W fiber gas Raman laser at 1153 nm

“…The details of the fabrication between the HCF and end-cap can be found in Refs. [25, 26]. The other end is fixed in the gas cell, which can be used to fill the HC-PCF with H 2 .…”