Dynamic intrinsic spectrum reconstruction of narrow-linewidth laser based on band-extended frequency noise

Abstract

Narrow-linewidth lasers have extensive applications due to advantages of low phase noise and high coherence. To explore the dynamics of narrow-linewidth lasers, the intrinsic spectrum is a kernel parameter which can show the dynamical coupling strength between the spontaneous emission and the stimulated emission in a laser cavity. Herein, we propose an intrinsic spectrum measurement method of narrow-linewidth lasers based on the band-extended frequency noise, which can improve the spectrum resolution. In the experiment, we successfully apply the method to the measure the linewidth compression dynamics of external-cavity distributed feedback lasers. The proposed measurement method can dynamically characterize the fast evolution process of the laser intrinsic spectrum with wide-range linewidth fluctuations, which will benefit for the dynamics research of narrow-linewidth lasers and tunable lasers.