High performance fiber laser resonator for dual band (C and L) sensing

This work presents an experimental analysis and comparison of the performance of quasi-randomly distributed reflectors inscribed into a single-mode fiber as a sensing mirror both in C- and L-band. Single-wavelength emission has been obtained in either band when using these artificially controlled backscattering fiber reflectors in a ring-cavity fiber laser. Single-longitudinal mode operation with an optical signal to noise ratio (OSNR) of 47 dB and an output power instability as low as 0.04 dB have been measured when employing a C-band optical amplifier. When replaced by an L-band optical amplifier, a single-longitudinal mode behavior has also been obtained, showing an OSNR of 44 dB and an output power instability of 0.09 dB. Regarding their performance as fiber-laser sensing systems, very similar temperature and strain sensitivities have been obtained in both bands, comparable to fiber Bragg grating sensors in the case of temperature and one order of magnitude higher in the case of strain variations. This work was supported in part by the MCIN/AEI/10.13039/501100011033 and FEDER A way to make Europe under Grant PID2019-107270RB, in part by the Ministerio de Educación, Cultura y Deporte of Spain under Ph.D. Grant FPU2018/02797, and in part by MCIN/AEI/10.13039/501100011033 and the European Union Next generation EU/PTR under Grant PDC2021-121172.