Chen Mo, Meng Zhou, Wang Jianfei, Chen Wei
Opt Express. 2015 Mar 9;23(5):6803-8. doi: 10.1364/OE.23.006803.
We study the method of Voigt profile fitting for ultra-narrow linewidth measurement. It filters out the effect of the spectrum broadening due to the 1/f frequency noise and extracts out the Lorentzian lineshape from the measured spectrum. The resolution is thus greatly promoted than the direct measurement from the self-heterodyne technique. We apply this method to an ultra-narrow-linewidth (~40 Hz by heterodyne beat technique) Brillouin/erbium fiber laser. The linewidth estimated from Voigt fitting method is indicated to be more accurate. In contrast, the linewidths estimated direct from the 3-dB and the 20-dB heterodyne-spectrum width are far over the true linewidth of the BEFL. The Voigt fitting method provides an efficient tool for ultra-narrow-linewidth measurement. And compared with heterodyne beat technique, it is applicable for all types of lasers.
我们研究了用于超窄线宽测量的沃伊特轮廓拟合方法。它滤除了由于1/f频率噪声导致的光谱展宽效应，并从测量光谱中提取出洛伦兹线形。因此，与自外差技术的直接测量相比，分辨率得到了极大提高。我们将此方法应用于超窄线宽（通过外差拍频技术约为40 Hz）的布里渊/铒光纤激光器。通过沃伊特拟合方法估计的线宽被证明更准确。相比之下，直接从3 dB和20 dB外差光谱宽度估计的线宽远超过布里渊/铒光纤激光器的真实线宽。沃伊特拟合方法为超窄线宽测量提供了一种有效的工具。并且与外差拍频技术相比，它适用于所有类型的激光器。
