High-power synchronous multi-wavelength solitons from a multimode mode-locked fiber laser system

In this Letter, we implement a multimode fiber (MMF) laser system mode-locked by a nonlinear polarization rotation technique for controllable synchronous multi-wavelength soliton generation. The synchronization of the repetition rates for different wavelengths is realized by the special mode transmission in MMF. For dual-wavelength mode-locking at 1566.7 nm and 1617.2 nm, each of the synchronously mode-locked solitons consists of a train of quasi-periodic beat pulses with a pulse width of 84 fs and period of 162 fs. The total output power reaches 532 mW with optimally balanced two-color intensities. Furthermore, switchable dual- and tri-wavelength synchronized femtosecond pulses are also obtained. In contrast to previous reports, this synchronously mode-locked multi-wavelength is output directly from a laser oscillator, which provides a simpler candidate to achieve pulse synchronization.