Laser guide stars based on the mesospheric sodium layer are becoming increasingly important for applications that require correction of atmospheric scintillation effects. Despite several laser approaches being investigated to date, there remains great interest in developing lasers with the necessary power and spectral characteristics needed for brighter single or multiple guide stars. Here we propose and demonstrate a novel, to the best of our knowledge, approach based on a diamond Raman laser with intracavity Type I second-harmonic generation pumped using a 1018.4 nm fiber laser. A first demonstration with output power of 22 W at 589 nm was obtained at 18.6% efficiency from the laser diode. The laser operates in a single longitudinal mode (SLM) with a measured linewidth of less than 8.5 MHz. The SLM operation is a result of the strong mode competition arising from the combination of a spatial-hole-burning-free gain mechanism in the diamond and the role of sum frequency mixing in the harmonic crystal. Continuous tuning through the Na D line resonance is achieved by cavity length control, and broader tuning is obtained via the tuning of the pump wavelength. We show that the concept is well suited to achieve much higher power and for temporal formats of interest for advanced concepts such as time-gating and Larmor frequency enhancement.

中文翻译：

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钻石钠导星激光

对于需要校正大气闪烁效应的应用，基于中层钠层的激光导星变得越来越重要。尽管迄今为止已经研究了几种激光方法，但是仍然对开发具有更亮的单颗或多颗恒星所需的必要功率和光谱特性的激光器非常感兴趣。在此，据我们所知，我们提出并展示了一种新颖的方法，该方法基于使用1018.4 nm光纤激光器泵浦的腔内I型二次谐波产生的金刚石拉曼激光器。从激光二极管以18.6％的效率获得了在589 nm输出功率为22 W的第一个演示。激光器以单纵向模式（SLM）运行，测得的线宽小于8.5 MHz。SLM操作是钻石中无空洞的增益机制与谐波晶体中和频混合作用的结合所产生的强模式竞争的结果。NaD线谐振的连续调谐是通过控制腔长来实现的，而通过泵浦波长的调谐可获得更宽的调谐范围。我们表明，该概念非常适合于实现更高的功率以及高级概念（例如时间门控和Larmor频率增强）的感兴趣的时间格式。通过泵浦波长的调整可以获得更宽的调整范围。我们表明，该概念非常适合于实现更高的功率以及高级概念（如时间门控和Larmor频率增强）的时间格式。通过泵浦波长的调整可以获得更宽的调整范围。我们表明，该概念非常适合于实现更高的功率以及高级概念（例如时间门控和Larmor频率增强）的感兴趣的时间格式。