We report a high-power source of continuous-wave (cw) mid-infrared (mid-IR) radiation at 2.26 $\mu \text{m}$ based on difference-frequency-generation (DFG) of a cw Yb-fiber laser at 1.064 $\mu \text{m}$ and a cw Tm-fiber laser at 2.010 $\mu \text{m}$ in MgO:PPLN. Using a 50-mm-long crystal with a single grating period of 32.16 $\mu \text{m}$ and a simple single-pass setup, we generate up to 3.84 W of cw output power at $2.26~\mu \text{m}$ at a power conversion efficiency of ~0.47%/W. The DFG output beam is characterized by a Gaussian TEM ₀₀ spatial profile with $M^{2} < 1.2$ , and exhibits excellent passive power stability of 0.6% rms and spectral stability better than 0.01% over 1 hour. We find close agreement between the measured conversion efficiencies and theoretical predictions, confirming optimum performance of the DFG source. Our approach represents a viable and practical alternative to the existing methods for generating this useful wavelength. To the best of our knowledge, the generated output represents the highest cw power obtained from any single-pass nonlinear frequency conversion source in the mid-IR.

中文翻译：

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2.26 μm 高功率、连续波、光纤泵浦差频生成

我们报告了2.26的大功率连续波（cw）中红外（mid-IR）辐射源 $\mu \text{m}$ 基于 1.064 的连续镱光纤激光器的差频生成 (DFG) $\mu \text{m}$ 和 2.010 的连续 Tm 光纤激光器 $\mu \text{m}$ 在 MgO:PPLN 中。使用 50 毫米长的晶体，单光栅周期为 32.16 $\mu \text{m}$ 和一个简单的单程设置，我们产生高达 3.84 W 的 cw 输出功率 $2.26~\mu \text{m}$ 功率转换效率约为0.47％/ W。DFG 输出光束的特点是具有高斯 TEM ₀₀空间分布 $M^{2} < 1.2$ ，并在 1 小时内表现出 0.6% rms 的出色无源功率稳定性和优于 0.01% 的光谱稳定性。我们发现测量的转换效率与理论预测之间非常吻合，证实了 DFG 源的最佳性能。我们的方法代表了生成这种有用波长的现有方法的可行且实用的替代方案。据我们所知，生成的输出代表从中红外中的任何单通非线性频率转换源获得的最高连续波功率。