Wu Lijin, Ji Zhonghua, Ma Weixin, Su Dianqiang, Zhao Yanting, Xiao Liantuan, Jia Suotang
Appl Opt. 2024 Mar 1;63(7):1847-1853. doi: 10.1364/AO.510265.
A method called the optimal demodulated Lorentzian spectrum is employed to precisely quantify the narrowness of a laser's linewidth. This technique relies on the coherent envelope demodulation of a spectrum obtained through short delayed self-heterodyne interferometry. Specifically, we exploit the periodic features within the coherence envelope spectrum to ascertain the delay time of the optical fiber. Furthermore, the disparity in contrast within the coherence envelope spectrum serves as a basis for estimating the laser's linewidth. By creating a plot of the coefficient of determination for the demodulated Lorentzian spectrum fitting in relation to the estimated linewidth values, we identify the existence of an optimal Lorentzian spectrum. The corresponding laser linewidth found closest to the true value is deemed optimal. This method holds particular significance for accurately measuring the linewidth of lasers characterized as narrow or ultranarrow.
一种称为最优解调洛伦兹光谱的方法被用于精确量化激光线宽的窄度。该技术依赖于通过短延迟自外差干涉测量获得的光谱的相干包络解调。具体而言，我们利用相干包络光谱内的周期性特征来确定光纤的延迟时间。此外，相干包络光谱内对比度的差异作为估计激光线宽的基础。通过绘制解调洛伦兹光谱拟合的决定系数与估计线宽值的关系图，我们确定了最优洛伦兹光谱的存在。最接近真实值的相应激光线宽被视为最优。该方法对于精确测量窄或超窄激光的线宽具有特别重要的意义。
