Huang Shihong, Wan Minggui, Wu Jiayang, Zhang Bingzhi, Liu Cuihong, Lu Dunke, Fang Xiaohui
Opt Express. 2023 Aug 28;31(18):28891-28899. doi: 10.1364/OE.497303.
In this paper, the effects of optical power factors like laser power, the powers of the laser beams in the two arms of the optical system, and the power of the photodetector on laser-linewidth measurements are studied. From the experiments, it can be found that when the average optical input power for the photodetector is about 50% of its linear saturation power, the measured laser line width is a minimum. When the optical powers of the laser beams in the two arms are equal in short-delay self-homodyne system, the measured laser line width is narrowest. In the low output power range of the laser, its line width decreases with the increase in optical power. By comparing experiments, it can also be clear that the conventional measurement method is seriously affected by different noise types, which causes the measured line width to become wider and not change even if the laser linewidth changes. However, based on the short-delay coherent envelope method, the measured coherent envelope changes significantly when the laser line width changes slightly, and its corresponding laser-linewidth values are also clearly visible. It confirms the low noise and high resolution of the short-delay self-homodyne coherent-envelope laser-measurement method. The outcomes of this study can provide helpful information for precision ultra-narrow laser-linewidth measurements.
本文研究了诸如激光功率、光学系统两臂中激光束的功率以及光电探测器的功率等光功率因素对激光线宽测量的影响。通过实验发现，当光电探测器的平均光输入功率约为其线性饱和功率的50%时，测得的激光线宽最小。在短延迟自外差系统中，当两臂中激光束的光功率相等时，测得的激光线宽最窄。在激光器的低输出功率范围内，其线宽随光功率的增加而减小。通过对比实验还可以清楚地看到，传统测量方法受到不同噪声类型的严重影响，这导致测得的线宽变宽，即使激光线宽发生变化也不会改变。然而，基于短延迟相干包络法，当激光线宽稍有变化时，测得的相干包络会有显著变化，其相应的激光线宽值也清晰可见。这证实了短延迟自外差相干包络激光测量方法的低噪声和高分辨率。本研究结果可为精密超窄激光线宽测量提供有用信息。
