Narrow linewidth erbium-doped fiber laser incorporating with photonic crystal fiber based Fabry-Perot interferometer for temperature sensing applications

We propose a narrow linewidth ring cavity erbium-doped fiber laser based on a photonic crystal fiber (PCF) based Fabry-Perot interferometer (F-P). A 5.2-m-long erbium-doped fiber was used in the resonant cavity as gain medium. The F-P was fabricated by cascaded with single-mode fiber and 2 mm length PCF as the interferometer filter, and the interferometer period was 0.58 nm. The laser threshold was 57 mW in the experiment, and 1573.99 nm narrow linewidth lasing was realized and 3 dB linewidth was 0.2 nm. Single wavelength laser temperature sensing was implemented by heating and cooling the F-P filter. In the experiment, single-wavelength lasing could be tuned from 1573.25-1574.27 nm within 40-120 degrees C, with 12.6 pm/degrees C sensitivity, power fluctuation was lower than 1.78 dB, and linearity was more than 0.996. The single-wavelength laser temperature stability was tested, and power fluctuation was less than 0.819 dB within 25 min scan time. In addition, four different dual-wavelength lasers could be obtained with power shift less than 1.187 dB.