采用离线和在线两种方式对光纤激光器的增益光纤进行γ射线辐照,实验研究了γ射线辐照对激光器功率特性的影响。通过离线辐照实验发现,经过一定剂量的射线辐照,当泵浦功率大于某一值之后,光纤激光器的斜率效率基本保持不变。通过总辐射剂量为2580 Gy的在线辐照实验发现,激光器的输出功率在辐照初期呈指数衰减,降到最低值之后,会出现小幅的回升,然后趋于稳定。通过计算光纤激光器在两种辐照方式下的功率退化率随辐射剂量的变化规律后发现,在辐照的初期,在线辐照激光器的功率退化率较大,但是随着辐射剂量的增加,两种辐照方式下激光器的功率退化率逐渐趋于一致。采用光纤辐致损耗的色心理论对实验结果进行了初步解释。

Herein, the influence of gamma-ray radiation on laser power characteristics is investigated experimentally by irradiating the gain fiber of a fiber laser with gamma rays in off- and on-line modes. In the off-line irradiation experiments, it is found that the slope efficiency of the fiber laser remains unchanged when the pump power is larger than a certain value. In the on-line irradiation experiments, with a total radiation dose of 2580 Gy, it is found that the laser output power decreases exponentially during the initial stages of irradiation until it reaches the lowest value, then increases slightly, and thereafter tends to be stable. The variations of power degradation rates with radiation dose under two different irradiation modes are compared, and the power degradation rate of the on-line irradiation laser is found to be higher during the initial stages of irradiation. With the accumulation of radiation dose, the power degradation rates of fiber lasers irradiated in both on-line and off-line modes tend to be consistent. These preliminarily experimental results are explained using color center theory of fiber radiation-induced loss.