Passively harmonic mode-locked fiber laser with controllable repetition rate based on a carbon nanotube saturable absorber

We have proposed and demonstrated a passively harmonic mode-locked fiber laser based on a single-walled carbon nanotube saturable absorber (SWCNT-SA) that has a controllable repetition rate. With the pump power fixed, we have experimentally observed harmonically mode-locked optical pulses with repetition rates that can be controlled over the range from the fundamental to the seventh-order mode through careful adjustment of the polarization controller only. From the experimental results, we deduce that the likely origin of the self-stabilization is the result of global and local soliton interactions induced by the continuous wave (CW) components.