Experimental Study On The High Power Continuous Tm:YAP Lasers

The band of2μm laser has experienced nearly half a century of development, and widely used in the scientific research, military, laser medical treatment, environmental protection, materials processing, etc. Due to2microns laser are superior in many respects nature,2microns laser has become an important area of research in the solid state laser. In view of its important application value, we carry out the Tm:YAP laser on the theoretical analysis and experimental research. The mainly work includes the following five aspects:(1) We carry out the characteristics research of the Tm:YAP crystal, inncluding four aspects:ion level structure properties of Tm3+, physical properties of YAP crystals, Tm:YAP crystal spectral characteristics and the Tm:YAP crystal thermal lens effect. As these four characteristics, we mainly study the Tm:YAP crystal thermal lens effect, including the the theoretical derivation and numerical calculation combined with specific parameters of the Tm:YAP crystal thermal lens focal length.(2)We establish the rate equations model of Tm:YAP laser, including:the four low energy level rate equation model of Tm:YAP laser and the rate equation model of the continuous Tm:YAP laser. The research of laser emitting mechanism is the basis of the study of laser, and the rate equation is the main basis of the laser working process. Through the establishment of the model and solving the rate equations, we can analyse the effect of various factors on the laser output, which is the basis for the optimization design of the laser.(3) We analyse the straight cavity theory model. The stable range of the laser and the changes of the laser spot radius in the cavity is simulated using the MATLAB software optimizing a cavity design. Combining with the experiment, the output power of various cavity type is compared in order to choose the best cavity type of continuous Tm:YAP laser which has effective compensation for Tm:YAP crystal thermal effect. Then, the Tm:YAP laser with stability and high power is realized. Under the input pump power of17W, the highest output power reaches4.92W with5%transmittance corresponding to slope efficiency of36.57%. The free running laser spectrum of Tm:YAP is measured by a ANDOR spectrograph, and the corresponding central wavelength is1985nm.The NanoScan beam measuring instrument is used measuring the light spot outline outputing in the same position under different pump power.(4) We study a Z cavity theory model of Tm:YAP laser. A four mirrors fold cavity is designed according to the stability of the four mirrors fold cavity and the condition of the astigmatism compensation. Then we optimize the design cavity using the MATLAB software. Combined with the experiment, the output power of various cavity type is compared in order to select the best type of cavity. In this type of the fold cavity, we get the maximum output power of2.27W and the slope efficiency of23.9%, while the input power is14W.(5) We carry out the research of theoretical design of tunable Tm:YAP laser, mainly including the analysis of the design and working principle of birefringent filter. The basic theory of the tunable Tm:YAP laser which accomplished through inserting the birefringent filter and brinell board in the cavity is analyzed.