【摘要】 针对传统延时自外差法测量窄线宽激光器线宽时延时光纤长度需大于6倍相干长度的严格约束，在深入分析延时自外差测量原理的基础上，建立了适用于延时光纤长度小于此极限情况的激光器线宽精确测量理论模型。通过开发数值仿真算法，推导并验证了所提模型的准确性，进一步提出了确定短延时光纤下保证测量精度的最短光纤长度计算方法。选取55 km和2 km延时光纤分别对3 kHz和100 kHz两激光器进行线宽测量，计算得到激光器线宽分别为3.066 kHz和108.6 k Hz，实验结果均满足误差要求，证明延时自外差法测量窄线宽激光器线宽时判别延时光纤所需最短长度的有效性，为优化窄线宽激光器线宽测试方法提供了理论依据和实践指导。更多还原

【Abstract】 Concerning the strict constraint in traditional time-delayed self-heterodyne measurements of narrowlinewidth laser linewidth, where the delayed fiber length must exceed six times the coherence length, an accurate theoretical model for laser linewidth measurement applicable when the delayed fiber length falls below this limit is established. The proposed model is developed based on an in-depth analysis of the time-delayed self-heterodyne measurement principle. Through the development of a numerical simulation algorithm, the accuracy of the proposed model is rigorously derived and verified. Furthermore, a calculation method is proposed to determine the minimum delayed fiber length required to ensure measurement accuracy under shortfiber conditions. Experimental linewidth measurements are performed using 55 km and 2 km delayed fibers on two lasers with linewidths of 3 kHz and 100 kHz, respectively. The calculated linewidths of the lasers are 3.066 kHz and 108.6 kHz respectively. The results from both experiments meet the specified error requirements, thereby validating the effectiveness of the proposed criterion for determining the essential minimum delayed fiber length in time-delayed self-heterodyne measurements of narrow-linewidth laser linewidth. This provides a solid theoretical framework and practical methodology for optimizing the measurement techniques of narrowlinewidth laser linewidth.更多还原