Research On Thulium Doped Pulse Laser Using SESAM

In recent years,2.0 μm thulium-doped pulse laser has been developing rapidly. It is widely used in some areas, such as laser medical, laser LIDAR and mid-infrared supercontinuum generation. The pulse obtained by mode-locked pulse fiber laser has advantages including narrow pulse width, good stability, high pulse energy, high repetition rate and so on. There are two categories to achieve pulse operation, actively mode-locked method and passively mode-locked method. Because of the actively mode-locked fiber laser cavity import the external modulator, it’s vulnerable to the external environment and difficult to achieve all-fiber structure. The passively mode-locked fiber laser is realized by Graphene, carbon nanotubes, SESAM, this fiber laser has advantages including in good stability and easy for all-fiber structure. The content is as follows:1. Introducing the advantages, applications and the development of the thulium-doped pulse laser. Making a contrast of actively and passively mode-locked technology. Deducing the thulium-doped fiber rate equation and the transmission equation of the pulse in the fiber and introducing the numerical method.2. Building the simulation model of the thulium-doped pulsed fiber laser based on SESAM. Analyzing the SESAM mode-locked mechanism and the characteristics of the thulium-doped pulsed fiber laser.3. With the above model, the course from never clamping to continuous mode locking has been simulated. The influence of pump power, doping concentration, the length of thulium-doped fiber, the length of single-mode fiber, depth of modulating and the ration of the coupler on the pulse laser has been studied. The result shows that, the pulse width becomes narrower with the increasing pump power, the doping concentration and the length thulium-doped fiber. The pulse width becomes narrower with increasing the depth of modulating and the length of single-mode fiber. After optimizing, the width of the pulse obtained by the fiber laser is 41 ps, the average power is 1.69 W, the energy of a single pulse is 214 nJ, and the peak power is 5219 W.