在Pr3+:ZBLAN光纤中, 运用粒子数速率方程理论, 研究用586 nm和335 nm连续激光双光子激发4f组态最高能级1S0, 以1S0和3F4为激光上下能级实现250 nm上转换紫外激光的动力学行为, 得到阈值抽运功率、激光输出功率、斜率效率和最佳光纤长度等激光参数。结果表明, 阈值抽运功率随光纤长度增加而增大, 斜率效率随光纤长度增加而减小, 光纤较短时, 无法获得较高输出功率。掺杂浓度越大则阈值抽运功率越小, 斜率效率越大。在选取的特定条件下, 斜率效率最高可达16.7%。

The theory of population rate equations was used to investigate the kinetics of upconversion ultraviolet laser based on the highest level 1S0 of 4f configuration in Pr3+:ZBLAN fiber. 586 nm and 335 nm pumping lasers are used to populate 1S0 level through stepwise two-photon absorption, and 250 nm ultraviolet (UV) continuous wave (CW) laser can be achieved by laser transition from 1S0 to 3F4. The threshold pump powers, output power, slope efficiency and optimum cavity length are calculated. The results show that the threshold pump power increases with the fiber length, and slope efficiency decreases with the increase of fiber length. Higher output power cannot be obtained in a short fiber. Moreover, higher doping concentration makes laser oscillate with lower threshold pump powers but higher slope efficiency. The best slope efficiency is 16.7% in the conditions taken in this paper.