Fig. 1. Schematic diagram of research framework

Fig. 2. Schematic diagrams of anti-resonant reflection guiding light^{[20, 34]}. (a) Coherent reflection enhancement of light by dielectric films; (b) anti-resonant reflection waveguide and its supported transmission spectrum

Fig. 3. Different anti-resonant hollow-core fiber structures. (a) Kagome fiber^[39]; (b) hypocycloid-core Kagome fiber^[40]; (c) single-ring negative-curvature hollow-core fiber^[41]; (d) ice cream-type hollow-core fiber^[42]; (e) nodeless negative-curvature hollow-core fiber^[43]; (f) nested hollow-core fiber^[44]; (g) conjoined-tube fiber^[45]; (h) nested nodeless anti-resonant hollow-core fiber^[46]; (i) double-nested anti-resonant hollow-core fiber^[47]; (j) truncated-tube double-nested anti-resonant hollow-core fiber^[48]

Fig. 4. Single-mode anti-resonant hollow-core fiber structure and single-mode characteristics^[51]. (a) Sketch of the fiber structure; (b) loss and figure of merit for fundamental mode and high order mode; (c) figure of merit for different fibers

Fig. 5. Improved single-mode anti-resonant hollow-core fiber. (a) Double cladding structure^[37]; (b) heptagonal core structure^[52]

Fig. 6. High modal purity anti-resonant hollow-core fiber. (a) Hybrid-lattice structure^[53]; (b) truncated cladding structure^[48]

Fig. 7. Single-mode laser transmission. (a) High-power long-distance single-mode laser transmission^[55]; (b) single-mode pulse laser transmission^[56]; (c) narrow-linewidth laser transmission^[57]

Fig. 8. Required mode groups of multi-mode anti-resonant hollow-core fiber^[66]. (a) Maximum average power output, M² value, and mode groups required for different M² at 95% coupling efficiency of reported high power laser sources; (b) relationship between the number of anti-resonant units, core size, and mode groups

Fig. 9. Multi-mode anti-resonant hollow-core fiber and laser transmission characteristics. (a) Single-ring cladding structure^[67]; (b) laser transmission based on single-ring cladding multi-mode anti-resonant hollow-core fiber^[68]; (c) nested multi-mode anti-resonant hollow-core fiber and characterization of mode performance^[69]

Fig. 10. Gas filling inside the anti-resonant hollow-core fiber enables mode control^[71] (a) and high-order mode selective transmission^[72] (b)

Fig. 11. Single-layer polarization-maintaining anti-resonant hollow-core fiber. (a) Birefringence curve^[78]; (b) measured group birefringence compared with simulation^[79]

Fig. 12. Nested polarization-maintaining anti-resonant hollow-core fiber. (a) Measured group birefringence and phase birefringence^[80]; (b) simulation and experimental results comparison for improved polarization-maintaining fiber^[81]