Real-time observation of pulsating solitons with central wavelength oscillation in an ultrafast fiber laser

Abstract

We present an experimental observation of pulsating solitons with central wavelength oscillation in an ultrafast fiber laser. The spectral features of the solitons are identified by virtue of the dispersive Fourier transform technique. In this pulsating regime, the central wavelength of output solitons exhibits periodic redshift and blueshift, and the positions of their Kelly sidebands oscillate synchronously with the solitons. The corresponding field autocorrelation traces show that the pulse duration changes periodically. In addition, soliton snaking motion is observed in the temporal domain. Depending on the pump level, an intermittent pulsating state is found in the fiber laser operating in a transition regime between pulsating and stationary mode-locking states, where the quasi-stationary and energy-modulated solitons appear alternatively. Our results would stimulate further investigation of the pulsating dynamics in ultrafast fiber lasers.