title: Ultra-narrow linewidth measurement based on Voigt profile fitting.
abstract: 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.
authors.forename: Mo
authors.initials: M
authors.lastname: Chen
authors.forename: Zhou
authors.initials: Z
authors.lastname: Meng
authors.forename: Jianfei
authors.initials: J
authors.lastname: Wang
authors.forename: Wei
authors.initials: W
authors.lastname: Chen