Research Of Erbium-Doped Fiber Laser Based On The Nonlinear Optical Loop Mirror

The generation of ultrashort pulses is not only one of the key technologies to realize OTDM/WDM but also the front edge research about nonlinear optics and ultrafast optics. Comparing with traditional lasers, fiber lasers offer a number of advantages including small volume, weight light, compact structure, and high stability. Now it has become one of the hottest topics in the field of the ultrashort pulses. On the base of our laboratory environments, this dissertation is focused on mode-locked Er³⁺-doped fiber lasers that include:1,Review of research state and the potential applications and the development of the fiber laser in this dissertation. The advantages of different mode-locking techniques have been analyzed. The basic mode-locking principles and technology of the fiber laser especially the figure-of-eight passively mode-locked fiber laser are introduced in detail. And the stability of the mode-locked Er³⁺-deoped fiber ring laser was analyzed.2,The mode locking fiber laser is composed of a gain-flattened erbium doped fiber amplifier. The mode-locking mechanism is the nonlinear optical loop mirror. The pulse at 1561nm at a repetition rate 1.1MHz is obtained. The maximum output power of the pulse is 0.6mW with 434ps pulse width and 10nm spectrum width. After amplified by EDFA, the maximum power of the output pulse is 10.8mW and the center wavelength does not change, the spectrum width become slightly narrow, the output power increases greatly and the pulse width of the amplified pulse is 484ps. We also studied the relations of laser's threshold, pulse width to Different length of NOLM in experiment.3,Experimental study of the wavelength tunable passively mode-locked Er³⁺-doped fiber laser based on figure-of-eight cavity was presented. Wavelength tunable and stable mode-locked pulses are obtained by utilizing the additive pulse mode-locking technique based on nonlinear optical loop mirror associated with tunable fiber grating filter. By adjusting the tunable filter and orientation of polarization controllers, the mode-locked pulses at 1.1 MHz repetition rate with average output power fluctuation less than 0.8dBm, and tunable range from 1548nm to 1570nm are obtained.