High-precision narrow laser linewidth measurement based on coherent envelope demodulation

This paper presents a novel method for high-precision narrow laser linewidth measurement through demodulating the coherent envelope of the short delayed self-heterodyne interferometry spectrum. Our method based on short delayed self-heterodyne interferometry can ignore the influence of Gaussian broadening induced by 1/f frequency noise and eventually obtain the strict Lorentzian spectrum and the corresponding linewidth. The feasibility of the method has been verified via theoretical analysis, simulation, and experimentation. Compared to the conventional linewidth measurement method, the linewidth measured by our method is more accurate, especially in the field of narrow linewidth measurement.