| The gain media and the saturable absorber are the important parts to generate theultrafast laser which lead the development direction of ultrafast laser. So, in order toget better properties of ultrafast laser, people are always seeking the new gain mediaand the new saturable absorber. The Nd,Y:SrF2disordered crystal are alwaysattracting the widespread attention, because of excellent mechanical properties, highthermal conductivity and wide fluorescence emission line width. In recent years, thecarbon base saturable absorber including the carbon nanotubes and the graphene arefamous for the manufacture of low cost, wide range of modulation, shorter recoverytime. In this paper, using the novel carbon base saturable absorber, we studied thepulse output characteristic of the different crystals. The several aspects of researchcontents are as follows:1. We introduced the characteristics and the development of the Nd,Y:SrF2andTm:YAlO3(Tm:YAP) crystal. Summarize the preparation process and the respectivecharacteristics of the Single-walled carbon nanotubes (SWCNTs) and graphenesaturable absorbers.2. We analyzed the absorption, emission spectra properties of the Nd,Y:SrF2crystal.And, also analyzed the continuous and the Q-switched mode-locked Nd,Y:SrF2lasercharacteristics. The absorption line width and the emission line width of this crystalcan be controlled by adjusting the concentration of mixed Y3+ions. By choosingoptimizing Nd,Y codoping concentration, a emission FWHM of15nm has beenobtained from the Nd,Y:SrF2disordered crystal. Comparing the continuouscharacteristics of different doping concentration, we obtain the largest output power of830mW and the large slope efficiency of43.5%. Using the Cr4+:YAG as saturableabsorber, a diode-pumped passively Q-switched mode-locked laser operation isdemonstrated on the Nd,Y:SrF2crystal. We obtain the maximum average output pumppower of150mW, the highest pulse repetition rate of4.53kHz and the shortest pulsewidth of820.5ps. 3. Optimizing the traditional W type laser cavity, we realized the single-endedoutput of LD pumped Nd,Y:SrF2crystal mode-locked laser operation using thereflection type single-walled carbon nanotubes as a saturable absorber. At theabsorbed pump power of1.97W, the maximum average output pump power of319mW is observed corresponding to the highest pulse repetition rate of107.8MHz at thecenter wavelength of1056nm. Without any dispersion compensation, themode-locked laser delivered pulses as short as1.7ps. The experimental results showthat the Nd,Y:SrF2crystal is a kind of good performance of the laser crystal.4. For the first time, the LD pumped Tm: YAP crystal self-Q-switching is obtainedusing the simplest straight cavity and without the saturable absorber. At the absorbedpump power of7.04W, we obtain the maximum average output pump power of1.68W, the shortest pulse width of1.64μs and the highest pulse repetition rate of65.16kHz.5. Design optimization of X type resonant cavity, and used the monolayer grapheneas saturable absorber, the mode-locking of a diode-pumped Tm:YAP laser operatingwas demonstrated for the first time. With the absorbed pump power of7.67W, themode-locked output power reaches as high as256mW corresponding to centralwavelength of1988.5nm. The experimental results show that, the graphene is apromising saturable absorber in the2μm solid-state ultrashort laser. |
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