Fig. 1. ARROW structure and its transmission spectrum^[18]

Fig. 2. SEM images of HC-ARFs. (a) Kagome HC-ARF^[21]; (b) ice-cream type HC-ARF ^[22]; (c) nodeless HC-ARF ^[23]; (d) conjoined-tube HC-ARF^[24]; (e) nested HC-ARF^[25]; (f) double nested HC-ARF^[26]

Fig. 3. Loss of HC-ARFs compared to the intrinsic loss limit of pure silica core SMF^[26]

Fig. 4. Schematic of typical setup of high-power laser transmission system based on HC-ARF

Fig. 5. Long-distance transmission experiment of high power laser based on nested HC-ARF^[11]. (a) Diagram of transmission experimental setup; (b) SEM image of nested HC-ARF with corresponding transmission loss spectrum and dispersion curve; (c) output power and transmission efficiency versus input power; (d) input and output spectra at different powers

Fig. 6. Experiment of narrow linewidth high-power laser long-distance transmission^[32]. (a) Diagram of experimental setup; (b) thermal image of fiber input and cladding light stripper for 2.3 kW input power; (c) output power as a function of input power; (d) output spectra characterization of laser source and HC-ARF

Fig. 7. Experiment of 3 kW continuous-wave laser hundred meters transmission^[14]. (a) SEM image of the multimode nested HC-ARF used in experiment; (b) output power and transmission efficiency as a function of input power

Fig. 8. Experiment of high peak power ultrafast laser transmission^[13]. (a) Diagram of experimental setup; (b) variation of input single-pulse energy and energy density at the quartz-wall with fiber core diameter of HC-ARF

Fig. 9. Experiment of high-power laser flexible transmission at 2 µm band^[27]. (a) SEM image of the fabricated nested HC-ARF; (b) loss spectra of the fiber; (c) differential group delay plot from spectral and spatial imaging technique through 10 m (solid) and 70 m (dashed) of fiber; (d) evolution of the output average power through a 6-m-long nested HC-ARF with the increase of the input average power, where the inset shows fiber-delivered near field beam profile

Fig. 10. Experiment of high-power green laser transmission^[29]. (a) Variation of output power with input power for different transmission lengths; (b) spectra comparison between the 15 m PCF and 15 m or 300 m HC-ARFs after laser transmission