Investigation Of Characteristics,Mechanism And Thermal Management Of Transversely Pumped DPALs

Diode pumped alkali vapor lasers (DPALs), which both have the advantages of solid state lasers and vapor lasers, also have some promising features like the high quantum efficiency, the good optical performance of gain medium and the narrow linewidth. These lasers have many potential applications in laser cooling, remote energy transmission, Nuclear Magnetic Resonance on medical services and so on. It is meaningful to make research work on some physical and technical problems related to DPALs.A brief introduction on the development history, relevant technical solutions and kinetic models of diode pumped alkali vapor lasers was presented. The matching methodes of the spectral bandwidth of pump source with that of alkali atom D2absorption line was given from two aspects:compressing the bandwidth of diode laser by external cavity, and broadening the D2absorption line of alkali atoms by buffer gases considering the effects of isotopes, the hyperfine energy structure of Rb atom on the absorption cross sections. On the basis of analyzing and understanding the technical solution and laser mechanism of DPALs, a physical model was established to describe the laser emission mechanism of a diode transversely pumped Rb vapor laser. In reference to the reported working parameters in experiments, the influence of parameters such as the pump laser, the output coupler reflectivity, the cell length, the buffer gases pressure, the temperature on the output characteristics (power and the optical-optical efficiency) were quantitatively analyzed.Taking into consideration the amplification saturation effect, a physical model is built to illustrate the kinetic processes and the laser amplification mechanism of a diode side pumped alkali vapor laser MOPA system. The pump energy distribution inside the vapor cell is displayed, and two-side puming way is selected as the prefer approach. The influences of the parameters, such as the temperature, cell length, and pump power on the output performance, are simulated and analyzed. The gain saturation effect in the direction of cell axis is also discussed. The calculations have a good agreement with observations, which shows the validity of this model. A group of optimal parameters is obtained for further improving the output characteristics of a cesium laser MOPA system.A side-pumping configuration with six laser diode arrays is designed for the diode pumped alkali vapor laser. A physical model is established to describe the thermal lens effect in a high-power side-pumped cesium vapor laser. Distributions of the radial temperature and the optical path difference in the cesium vapor cell are simulated and analyzed. Influences of the pump power, the pump beam waist and the cell temperature on the thermal focal length are calculated and discussed. We present a simple and promising design of a scheme to compensate for the thermal lens of the cesium vapor laser. The compensation results are also presented. At last, the experimental studyonthe output performance of a diode single-end-pumped rubidium vapor laser was carried out, with the stable output power of～100mW at795nm..