Bound state of dissipative solitons in a nanotube-mode-locked fiber laser

The bound state of dissipative solitons (DSs) in a nanotube-based erbium-doped fiber laser is observed experimentally for the first time to our best knowledge. The bound-state DSs exhibit a rectangular spectrum profile accompanied by high-contrast modulated fringes on the top. The pulse duration of DSs is estimated as ~3.6 ps and the pulse–pulse separation is ~30 ps. The propagation dynamics of the bound-state DSs are further investigated by utilizing single-mode fiber with different lengths. It is found that the pulses can be compressed to ~208 fs and subsequently broadened linearly along the extracavity fiber, while the pu separation between the two bound-state DSs remains constant.