Tunable and Switchable Dual-Wavelength Dissipative Soliton Operation of a Weak-Birefringence All-Normal-Dispersion Yb-Doped Fiber Laser

We report on the generation of tunable and switchable dual-wavelength dissipative solitons (DSs) in a weak-birefringence all-normal-dispersion Yb-doped fiber laser based on the nonlinear polarization rotation technique. By virtue of the weak-birefringence operation, the switchable dual-wavelength DSs with a wide wavelength-tunable range and variable wavelength spacing are observed for the first time. The variable wavelength spacing is a result from the similar order of magnitude between the polarization controller-induced birefringence change and the fiber birefringence. It is suggested that a widely tunable wavelength spacing of the tunable and switchable dual-wavelength DSs could be realized through introducing an extra birefringence change whose magnitude is comparable with the fiber birefringence.