Modulated comb-like pulse distribution induced by intracavity Sagnac filtering in a fiber laser

Abstract We demonstrate experimentally a modulated comb-like pulse distribution generated from a mode-locked fiber laser with an intracavity Sagnac interferometer. The modulated comb-like pulse bunch profile is composed of a sequence of symmetrically distributed pulses with a fixed temporal separation. The modulated bunch profiles can be dynamically adjusted by manipulating the pump power and the polarization settings of the fiber laser. The pulse separation in the bunch is determined by the optical delay line of the Sagnac interferometer. We develop a theory to model our experimental results and calculate the transient generation process of the comb-like pulse bunch. The theoretical results are in accordance with the experimental results. For the first time the generation of the modulated comb-like pulse distribution is proved by theoretical and experimental analyses to be a result of intracavity Sagnac filtering. These results will help in realizing adjustable modulated pulse bunch generation in noise-driven dissipative systems for potential applications in laser measuring and information processing.