γ辐照对窄线宽光纤激光器的影响及光漂白效果

Influence ofγ-radiation on the output properties of narrow linewidth fiber laser and photo bleaching effect

采用γ射线对窄线宽光纤激光器的种子源进行辐照试验,辐照总剂量约50 krad(Si),并对比分析了辐照前后输出激光特性,种子源的功率衰减超过70%、增益光纤损耗增加、温度升高明显。对不同辐照剂量下的种子源进行功率放大,结果表明:放大后的激光输出功率、中心波长、3 dB线宽等未发生明显变化,但拉曼抑制比随辐照剂量的增加略微降低。采用793 nm和524 nm激光对辐照后的种子源进行漂白,验证了不同波长漂白光的恢复能力。在同等漂白功率条件下,由于524 nm激光的光子能量更高且对应于掺镱光纤辐致缺陷的主吸收峰,具有更快的漂白速度和更强的漂白能力。漂白试验结果表明,种子源输出功率与793 nm漂白时长呈线性关系、漂白速率约为0.30 W/h,种子源输出功率与524 nm漂白时长大体上呈拉伸指数函数关系、漂白速率约为1.65 W/h。

The radiation experiment on the seed stage of narrow line-width fiber lasers byγray radiation with total dose of 50 krad(Si)is conducted.The output properties of this seed laser are analyzed before and afterγradiation.Experimental results reveal that the output power declines over 70%,and the temperature of gain fiber rises significantly as the loss increases.The radiated seed source is amplified to kW power level,presenting little change of output power,central wavelength,and 3 dB bandwidth at different radiation dose.However,the SRS suppression slightly decreased with the increase of radiation dose.793 nm and 524 nm LDs with the same power are applied as bleaching sources of radiated seed stage,and the bleaching effect is analyzed.Due to higher photon energy and closer to the absorption peak of radiation-induced defects,524 nm LD presents a better bleaching effect.The output power of seed stage and 793 nm bleaching duration presents a linear relationship with a bleaching speed at 0.30 W/h,and the output power and 524 nm bleaching duration approximately presents a tensile-exponential function relationship with a bleaching speed at 1.65 W/h.