High Fundamental-Repetition-Rate Bound Solitons in Carbon Nanotube-Based Fiber Lasers

We demonstrate bound solitons formation with a high fundamental-repetition-rate of 211.8 MHz from an all-fiber linear-configuration mode-locked laser incorporating a carbon-nanotube-based saturable absorber for the first time. By adjusting the polarization state of laser cavity, bound solitons exhibit a large change of pulse separation in a range of 3.5-73 times longer than the pulsewidth, while the phase difference of the tightly bound solitons switches between $pm pi /2$ . Numerical simulations confirm the experimental observations about the dependence of spectral profile of bound solitons on the pulse separation and the phase difference.