A dual-wavelength fiber laser sensor with temperature and strain discrimination

This work presents a dual-wavelength C-band erbium-doped fiber laser assisted by an artificial backscatter reflector. This fiber-based reflector, inscribed by femtosecond laser direct writing, was fabricated into a single mode fiber with a length of 32 mm. The dual-wavelength laser obtained, centered at 1527.7 nm and 1530.81 nm, showed an optical signal-to-noise ratio over 46 dB when pumped at 150 mW. Another feature of this laser was that the power difference between the two channels was just 0.02 dB, regardless of the pump power, resulting in a dual emission laser with high equalization. On the other hand, an output power level and a central wavelength instability as low as 0.3 dB and 0.01 nm were measured, in this order for both channels. Moreover, the threshold pump power was 40 mW. Finally, the performance of this dual-wavelength fiber laser enhanced with a random reflector for sensing applications was studied, achieving the simultaneous measurement of strain and temperature with sensitivities around 1 pm/ue and 9.29 pm/°C, respectively.This work is part of the projects PID2019-107270RB, funded by MCIN/AEI/10.13039/501100011033 and FEDER “A way to make Europe”, and PDC2021-121172 funded by MCIN/AEI/10.13039/501100011033 and European Union “Next generationEU”/PTR, the Ministerio de Educación, Cultura y Deporte of Spain (PhD grant FPU2018/02797)