中文摘要：

采用光纤激光器和放大器结构方案，观察到了高浓度掺镱光纤（YDF）的光子暗化（Photo-darkening）现象．对激光器阂值和输出功率、放大器输出谱的测量结果表明，光子暗化效应导致了高掺杂浓度YDF的功率转换效率随泵浦作用时间的增加而下降，且下降为单调不可逆过程，但随着泵浦时间的增加，这种下降逐渐变缓、功率转换效率最终可趋于稳定．

英文摘要：

The photodarkening in a commercial yitterbium-doped fiber （YDF） with high doping concentration was investigated. When the YDF was respectively used in a fiber laser and an amplifier, by measuring the threshold and output power of the laser,and the output spectra of the amplifier, it was found that the power conversion efficiency of the YDF decreases over the pumping time. Moreover, the decrease of power conversion efficiency was a monotonic and irreversible process. The decreasing may be gradually vanished as the pumping time increases.