Erbium-doped fiber laser based on FBGs-FP fabricated by femtosecond laser for temperature and strain sensing

In this paper, an erbium-doped fiber laser (EDFL) system based on intrinsic Fabry-Perot interferometer (IFPI) structure is proposed for simultaneous measurement of temperature and strain. IFPI with a central wavelength of 1546.2 nm, an interference fringe interval of 1.8 nm is composed of two FBGs inscribed by femtosecond laser and used as the frequency selective device in fiber laser. The signal-to-noise ratio (SNR) and 3-dB linewidth of 1546.2 nm fiber laser are 27.735 dB and 0.21 nm, respectively. For 1546.2 nm-laser stability, the maximum fluctuation of laser peak wavelength and output power is 0.08 nm and 0.655 dBm, respectively. Experimental results show that the proposed EDFL sensing system exhibits a temperature sensitivity of 9.16 pm/celcius, the linearity R2 is 0.99965 within the temperature range of 100 degrees C-800 degrees C and a strain sensitivity of 7.45 pm/& mu;& epsilon;, the linearity R2 is 0.99985 within the strain range of 0 & mu;& epsilon;-1050 & mu;& epsilon; at 800 degrees C. The stability of both maximum temperature and maximum strain was monitored within 30 min, and the maximum fluctuation of laser peak wavelength and output power was 0.12 nm and 0.372 dBm, 0.05 nm and 0.667 dBm, respectively.