In this paper we explore the application of low-loss multimode anti-resonant hollow-core fiber (MM-AR-HCF) in the delivery of nanosecond laser pulses at 1 µm wavelength. MM-AR-HCF with large core offers a rich content of low-loss higher-order modes which plays a key role in the efficient coupling and transmission of high-power laser of low beam quality. In the experiment, laser pulses of an average pulse energy of 21.8 mJ with 14.6 ns pulse width (corresponding a peak power of 1.49 MW) are transmitted through MM-AR-HCF of 9.8 m length without damage. 85% transmission efficiency is achieved where the incident laser beam suffers a low beam quality with M²_x and M²_y of 2.18 and 1.99 respectively. Laser-induced damage threshold (LIDT) of MM-AR-HCF was measured to be 22.6 mJ for 85% transmission efficiency, which is 7 times higher than that for a multimode silica optical fiber with a large core of 200 µm.

中文翻译：

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通过多模反谐振空芯光纤以 1 µm 波长传输纳秒激光脉冲

在本文中，我们探讨了低损耗多模反谐振空心光纤（MM-AR-HCF）在传输 1 µm 波长纳秒激光脉冲中的应用。大纤芯的MM-AR-HCF提供了丰富的低损耗高阶模含量，对于低光束质量的高功率激光的高效耦合和传输起着关键作用。实验中，平均脉冲能量为21.8 mJ、脉冲宽度为14.6 ns（对应峰值功率为1.49 MW）的激光脉冲穿过9.8 m长度的MM-AR-HCF而没有损坏。当入射激光束的光束质量较低（M ² _x和 M ² _y分别为 2.18 和 1.99）时，可实现 85% 的传输效率。测得 MM-AR-HCF 的激光诱导损伤阈值 (LIDT) 为 22.6 mJ，传输效率为 85%，比大纤芯 200 µm 多模石英光纤高出 7 倍。