Tunable distributed sensing performance in Ca-based nanoparticle-doped optical fibers

Rayleigh scattering enhanced nanoparticle-doped optical fibers is a technology very promising for distributed sensing applications, however, it remains largely unexplored. This work demonstrates for the first time the possibility of tuning Rayleigh scattering and optical losses in Ca-based nanoparticle-doped silica optical fibers by controlling the kinetics of the re-nucleation process that nanoparticles undergo during fiber drawing by controlling preform feed, drawing speed and temperature. A 3D study by SEM, FIB-SEM and optical backscatter reflectometry (OBR) reveals an early-time kinetics at 1870 degrees C, with tunable Rayleigh scattering enhancement 43.2-47.4 dB, regarding a long-haul single mode fiber, SMF-28, and associated sensing lengths of 3-5.5 m. At 2065 degrees C, kinetics is slower and nanoparticle dissolution is favored. Consequently, enhanced scattering values of 24.9-26.9 dB/m and sensing lengths of 135-250 m are attained. Finally, thermal stability above 500 degrees C and tunable distributed temperature sensitivity are proved, from 18.6 pm/degrees C to 23.9 pm/degrees C,similar to 1.9-2.4 times larger than in a SMF-28. These results show the promising future of Rayleigh scattering enhanced nanoparticle-doped optical fibers for distributed sensing. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement