对1550nm高功率窄线宽光纤放大器进行了实验研究。该放大器采用双级放大(MOPA)结构, 其中第一级预放采用5 m长的掺Er3+光纤, 将种子光信号放大到约90 mW; 采用15 m长的Er3+/Yb3+共掺双包层光纤放大器作为二级放大, 抽运源采用2支工作波长为980 nm的大功率激光二极管(LD), 抽运阈值功率约1.3 W。 当抽运功率为10.8 W时, 得到放大激光输出功率为1.97 W, 光-光转换效率为18 %, 斜率效率为21%, 增益大于13 dB。所采用的种子光源为1550 nm单频窄线宽(DFB)LD, 输出功率为10 mW; 采用延迟自外差方法对种子源及放大器输出的线宽进行测量, 测量结果显示该种子源及放大后的激光输出的3 dB线宽均约为220 kHz, 在目前的实验条件下, 没有观察到放大后的激光线宽展宽现象。

A 1550 nm high efficient narrow line width fiber amplifier was demonstrated. In this amplifier double-stages amplification (MOPA) structure was employed. For the 1st stage(preamplifier), a piece of 5 m Er3+ doped fiber amplifier was used to amplifier the seed laser signal to about 90 mW. And for the second-stage amplifier, a piece of 15 m Er3+/Yb3+co-doped double-clad fiber amplifier which was pumped by two high power 980 nm LDs was employed to exhibit 1.97 W output with 10.8 W pump power. The conversion efficiency and slope efficiency reached 18 % and 21 % respectively, and a gain of more than 13 dB was obtained. In the experiment, a single frequency narrow line width(DFB)semiconductor laser with a pigtail was used as the seed source. The wavelength of the laser was 1.5 μm, and the output power may reached to about 10 mW. The line width of laser was measured by the delayed self-heterodyne method, The 3 dB line width of seed source and amplified laser was about 220 kHz. Under our current environment and conditions, the phenomenon that amplified laser line width was broadened was not found.