The ongoing miniaturization of semiconductor lasers has enabled ultra‐low threshold devices and even provided a path to approach thresholdless lasing with linear input–output characteristics. Such nanoscale lasers have initiated a discourse on the origin of the physical mechanisms involved and their boundaries, such as the required photon number, the importance of optimized light confinement in a resonator, and mode‐density enhancement. Here, high‐β metal‐clad coaxial nanolasers, which facilitate thresholdless lasing are investigated. Both the conventional lasing characteristics, as well as the photon statistics of the emitted light at 10 K under continuous wave excitation are experimentally and theoretically investigated. While the former lacks adequate information to determine the threshold to coherent radiation, the latter reveals a finite threshold pump power. The work confirms an important aspect of high‐β lasers, namely that a thresholdless laser does have a finite threshold pump power and must not be confused with a hypothetical zero‐threshold laser. Moreover, the results reveal an excitation power dependent β‐factor which needs to be taken into account to correctly describe the experimental data.

中文翻译：

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依赖于激励功率的β因子的同轴纳米激光器在电信波长处无阈值过渡到相干发射

半导体激光器的不断小型化使得超低阈值的设备成为可能，甚至提供了一种以线性输入输出特性接近无阈值激光的途径。此类纳米级激光器已开始讨论所涉及的物理机制的起源及其边界，例如所需的光子数，优化谐振器中光限制的重要性以及增强模式密度。在这里，研究了高β金属包覆同轴纳米激光，该激光促进了无阈值激光。实验和理论研究了常规的激光特性以及在连续波激发下在10 K下发射光的光子统计。尽管前者缺乏足够的信息来确定相干辐射的阈值，后者显示了有限的阈值泵浦功率。这项工作证实了高β激光器的一个重要方面，即无阈值激光器确实具有有限的阈值泵浦功率，不能与假设的零阈值激光器相混淆。此外，结果揭示了与激励功率有关的β因子，必须正确考虑该因子才能正确描述实验数据。