Anti-resonant hollow-core fibers (AR-HCFs) have tremendous potential and wide-ranging applications in the field of high-power laser transmission due to their low nonlinear effect, low latency characteristic, and high damage threshold, which serve as a bridge for the application of high-power lasers in more scenarios. However, the current coupling of high-power lasers with AR-HCFs is mostly spatially structured coupling, which is susceptible to interference from the external environment and has poor stability. Therefore, the realization of all-fiber high-power laser transmission through AR-HCFs holds significant importance for practical applications.

This study utilizes a commercial fusion splicer to perform precision fusion splicing between the coated solid-core fiber (SCF) and AR-HCF. The two fibers are carefully selected to ensure optimal mode-field matching. By optimizing splicing parameters, low-loss splicing is accomplished with a relatively low discharge current (16.7 mA) and short discharge time (600 ms), while the mechanical strength of the splice points is enhanced through the re-discharge technology. The anti-reflection coating deposited on the end-face of the SCF can effectively mitigate Fresnel reflection-induced losses. Furthermore, a cladding power stripper (CPS) is installed after the splicing point of the AR-HCF, which significantly reduces the operating temperature of the fiber coating during high-power laser transmission. Consequently, stable kilowatt-level laser transmission through an all-fiber AR-HCF system is successfully achieved. The splicing loss is less than 0.22 dB.

We develop an all-fiber high-power laser transmission system based on AR-HCFs, with Fig.2 presenting both the experimental configuration and corresponding results. The laser source is a fiber oscillator, characterized by a wavelength of 1080 nm and a maximum output power of approximately 2700 W. Utilizing a 1.5 m long AR-HCF, a maximum output power of 2504 W is achieved, corresponding to a transmission efficiency of 92.2%. During a 15 min continuous monitoring, the output power remains highly stable when operating at maximum capacity, with power fluctuations kept well below 0.8%. Beam quality analysis reveals the^{beam quality factor M2 of 1.3, with excellent beam profile characteristics at the focal point. In this study, due to the relatively high loss of AR-HCFs in the laser wavelength band, the transmission length is limited. Therefore, future work will focus on extending this technology to diverse application scenarios by employing high-power fiber lasers at different spectral bands and low-loss AR-HCFs, aiming to achieve all-fiber AR-HCF laser transmission across broader spectra, higher power levels, and longer distances.}

We achieve the 2500 W all-fiber laser transmission by splicing a 1.5 m long AR-HCF with the coated SCF. The corresponding transmission efficiency is 92.2%.