Abstract Tunable, narrowband superfluorescent fiber sources (SFSs) are significantly important for spectral combination. Here, we propose a high power, tunable, ultra-narrowband Yb-doped SFS operating at wavelength less than 1055 nm with 20 nm tuning range. The system is composed of a broadband SFS, a home-mode space-to-fiber tunable spectral filter, and a three-stage amplifier chain. In order to achieve three typical characteristics, namely, operating in the shorter wavelength region (SWR) with wide spectrum, tunable and narrowband, and high-power output, the performance of the system is investigated and optimized based on the rate equations with temperature, grating monochromator and the coupling theory of Gaussian beam between fibers. Theoretical investigation indicates that a broadband SFS operating in the SWR with wide spectrum can be achieved by controlling temperature within a certain range. Moreover, by optimizing space-to-fiber tunable spectral filter, the tunable, ultra-narrowband SFS with linewidth of 0.088 nm can be obtained. In addition, the seed laser with signal to noise ratio (SNR) of more than 30 dB and the appropriate length of active fiber can gain better amplification performance from the main amplifier. Based on these optimized parameters, a high power, tunable, ultra-narrowband Yb-doped SFS has been built experimentally. The output power of narrowband SFS operating in tunable range from 1035 nm to 1055 nm exceeds 300 W with M2 factor of 1.47, and the measured full width at half maximum and SNR of which are less than 0.1 nm and beyond 30 dB, respectively. This work extends the spectral region and capacity of narrowband SFSs, and will be useful for further power scaling of spectral beam combination.

中文翻译：

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高功率、可调谐、超窄带掺镱超荧光光纤光源，工作波长小于 1055 nm，调谐范围为 20 nm

摘要 可调谐窄带超荧光光纤源 (SFS) 对于光谱组合非常重要。在这里，我们提出了一种高功率、可调谐、超窄带 Yb 掺杂的 SFS，其工作波长小于 1055 nm，调谐范围为 20 nm。该系统由宽带SFS、家庭模式空转光纤可调谐光谱滤波器和三级放大器链组成。为了实现在短波区（SWR）工作的宽光谱、可调谐窄带和高功率输出三个典型特性，基于速率方程与温度对系统性能进行研究和优化，光栅单色器和光纤间高斯光束的耦合理论。理论研究表明，通过将温度控制在一定范围内，可以实现工作在宽谱SWR的宽带SFS。此外，通过优化空间到光纤的可调谐光谱滤波器，可以获得线宽为 0.088 nm 的可调谐超窄带 SFS。此外，信噪比（SNR）大于30dB的种子激光器和适当长度的有源光纤可以从主放大器获得更好的放大性能。基于这些优化参数，实验构建了高功率、可调、超窄带掺镱SFS。窄带 SFS 工作在 1035 nm 至 1055 nm 可调范围内的输出功率超过 300 W，M2 因子为 1.47，测得的半峰全宽和 SNR 分别小于 0.1 nm 和超过 30 dB。