Research On Widely Tunable Narrow Linewidth Fiber Laser

As a sensor demodulation sourse, tunable fiber laser can realize sensing detection of single-point, multipoint and distributed fiber Bragg grating sensor array in the detection of Fiber Grating Sensors. In this paper, both of theoretical and experimental aspects of tunable erbium-doped fiber laser have been discussed.In theory, three-level pumping scheme for erbium-doped fiber laser have been studied based on the energy levels of erbium-doped fiber, obtained the threshold condition of the fiber laser. The thesis have an intensive study on the theoretical model of tunable ring fiber laser, and have a numerical simulation of the laser output in different erbium fiber length, different output coupling ratio, different cavity loss and different pump power.In the experiment, the erbium-doped fiber ring laser has been studied to obtain a fiber laser of an output power of 69mW, the output wavelength of 1562nm, linewidth of 42pm, the slope efficiency of 25.2%. Inserted a tunable Fabry-Perot (FP) filter as a wavelength tuning element in the ring cavity, we obtained a tunable erbium-doped fiber ring laser. The tunable laser have a tunable output wavelength range of 93nm (1502nm ~ 1595nm), the maximum linewidth among the entire tuning range is less than 40pm.We have improved the tunable erbium-doped fiber ring laser, to make sure a structural optimization and improvement of the structure. Double isolators have been used in the tunable erbium-doped fiber ring cavity with tunable laser wavelength range of 104nm(1513nm~1617nm), the maximum linewidth among the entire tuning range is less than 40pm. Base on the above research, a prototype of tunable erbium-doped ring fiber laser have been produced.The feasibility of the fiber laser to be used as a tunable light source in FBG sensing detection have been tested and verified. We have simulated the sensor detection process, and abtained the light intensity signal of the sensor grating in the experiment, to demonstrate the feasibility of the tunable light source in FBG sensing detection. Now the digital signal processing systems should being studied in our laboratory, and related practical study are in progress.