Microdrilled tapers to enhance optical fiber lasers for sensing

In this work, an experimental analysis of the performance of different types of quasi-randomly distributed reflectors inscribed into a single-mode fiber as a sensing mirror is presented. These artificially-controlled backscattering fiber reflectors are used in short linear cavity fiber lasers. In particular, laser emission and sensor application features are analyzed when employing optical tapered fibers, micro-drilled optical fibers and 50 μm-waist or 100 μm-waist micro-drilled tapered fibers (MDTF). Single-wavelength laser with an output power level of about 8.2 dBm and an optical signal-to-noise ratio of 45 dB were measured when employing a 50 μm-waist micro-drilled tapered optical fiber. The achieved temperature sensitivities were similar to those of FBGs; however, the strain sensitivity improved more than one order of magnitude in comparison with FBG sensors, attaining slope sensitivities as good as 18.1 pm/με when using a 50 μm-waist MDTF as distributed reflector. This work is part of the project PID2019-107270RB, funded by MCIN/ AEI/10.13039/501100011033 and FEDER 'A way to make Europe', the Ministerio de Educación, Cultura y Deporte of Spain (PhD grant FPU2018/02797), the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 838143, the Beatriz Galindo BEAGAL18/00116 fellowship, the 'Fundación Caja Navarra' and 'Fundación la Caixa' with the proyect LCF/PR/PR13/51080004 and Projects for young researchers UPNA 2019.