Fig. 1. The comparison of loss performance between three types of hollow core fibers and SMF^[3-19]

Fig. 2. Geometry of HCBF and it’s light guiding mechanism

Fig. 3. Cross-section of several typical HCPBF ^[13,15,17]

Fig. 4. Typical HCARF structure and it’s light guiding mechanism

Fig. 5. Cross-section of self-produced 7-cell and 19-cell HCPBF

Fig. 6. Output spectrum of 7-cell HCPBF at different bending diameters

Fig. 7. Output spectrum of 19-cell HCPBF at different bending diameter

Fig. 8. Bending loss test results of 19-cell HCPBF and 6-ring HCARF

Fig. 9. RIA as a function of total dose at 1 550 nm between HCPBF and SMF^[25]

Fig. 10. Single-wavelength lasing output in the range 1 562.5～1 565.8 nm of the proposed Novel Fiber Filter based on HCBF^[26]

Fig. 11. Experiment setup for temperature and gas pressure response^[30]

Fig. 12. 37×40 Gbit/s DWDM transmission system output and its adoption of 19-cell HCPBF^[17]

Fig. 13. The calculated transmission spectrum drift of a HCPBF filled with different refractive index liquids^[35]

Fig. 14. 11.5 km nested 5-ring HCARF transmission path ^[36]

Fig. 15. Photonic Tools’ high-power optical fiber connector^[38]

Fig. 16. Nested HCARF ring used in the resonator fiber optic gyro introduced by Honeywell ^[40]