Fig. 1. Signal-to-noise ratio in the distributed system of Rayleigh scattering sensing

Fig. 2. Rayleigh scattering in optical fibers

Fig. 3. Specific methods of fiber scattering enhancement

Fig. 4. Model of defect changes in optical fibers under ultraviolet light irradiation

Fig. 5. Microstructure category of scattering enhanced fiber

Fig. 6. Scattering spectrum estimation of scattering enhanced fibers prepared by various methods

Fig. 7. Relationship among signal-to-noise ratio, radius, and relative refractive index difference in optical fibers

Fig. 8. Model of backward collection coefficient of fiber scattering. (a) Numerical aperture; (b) mode-field radius

Fig. 9. Multimode fiber enhances the backscattering collection coefficient. (a) Structure of multimode fiber; (b) scattering spectrum

Fig. 10. Design of ultra long adiabatic tapered fiber to enhance scattering. (a) Scattering spectra of ULTF with a length of 12.5 km and radius of 4.5-3 μm; (b) scattering enhancement results and fiber length for different small end radius

Fig. 11. Parameter changes of ULTF. (a) Radius distribution; (b) scattering spectrum; (c) scattering enhancement value

Fig. 12. Tapered FBG array. (a) Schematic; (b) spectra; (c) scattering spectra

Fig. 13. Comparison of various scattering enhanced fiber enhancement methods