Dissipative dual-wavelength pulses synchronously mode-locked in a compact fiber laser

Exploiting the reflect pulse from the polarization beam splitter, synchronously mode-locked dual-wavelength dissipative sub-pulses have been obtained both numerically and experimentally in an Yb-doped passively mode -locked fiber laser. Numerical simulation results show that, the synchronous two sub-pulses are in fact the leading and trailing edges of the pulse circulating in the cavity, thus they are bounded together tightly and exhibit the same repetition rates all the time. However, different from the bound soliton in anomalous dispersion, the proposed dual-wavelength pulses behavior is unique. Owing to the liner chirp of the pulses, the interval between these two sub-pulses could be changed. When the pulses are passing through a segment of fiber with anomalous dispersion in the simulation or a pair of gratings in the experiment, the time interval can be getting even closer until the pulses are merged. In addition, the time interval can be extended when the pulses are passing through a segment of normal-dispersion fiber. Moreover, the central wavelengths of the two sub-pulses and the interval between them can be varied by fine tuning the cavity parameters, such as the pump power, the orientation of the wave plates or the central wavelength of the filter. Experimental results from an Yb-doped mode-locked fiber laser based on nonlinear polarization rotation agree very well with the simulation results.