High-efficiency 6-hole structure anti-resonant hollow-core fiber 2.79 μm Cr,Er:YSGG high-energy pulse laser transmission system

Using anti-resonant hollow-core fibers instead of light guide arms for laser energy transmission can greatly improve the flexibility of medical laser devices, reduce system complexity, and increase laser transmission efficiency. In this paper, a 6-hole anti-resonant air-core fiber (AR-HCF) with a length of 1.5 m and a core diameter of 78 μm is designed to transmit the radiation at 2.79 μm waveband. Utilizing our homemade medical solid-state Cr,Er:YSGG laser and coupling systems, we demonstrate, for the first time, the ability to transmit high-energy pulses at 2.79 μm wavelength through a full-silica microstructure hollow-core fiber. We analyze the characteristics of infrared laser transmission using this fiber. The results show that the average coupling transmission efficiency of this system reached 77.3 %, with a maximum coupling efficiency of 85 %. To our best knowledge, this transmission efficiency is the best value of 3 μm band erbium laser transmission by silica hollow microstructure fibers. The maximum output energy of the fiber is 11.78 mJ, corresponding to an energy density of 350 mJ/cm2, which far exceeds the energy density threshold required for tissue ablation. The uncooled fiber shows no damage during one hour of continuous operation in the experiment. This study's theoretical and experimental research also confirms that the bend radius meets the requirements for clinical medical instrument use. This 6-hole structure AR-HCF opens up a new pathway for medical devices requiring efficient transmission of 2.79 μm Cr,Er:YSGG medical solid-state laser.