We experimentally investigated the polarization vector characteristics in an Er-doped fiber laser based on graphene that was deposited on microfiber. A variety of dynamic states, including polarization locked fundamental soliton, and polarization domain wall square pulses and their harmonic mode locked counterparts have all been observed with different pump powers and polarization states. These results indicated that the microfiber-based graphene not only could act as a saturable absorber but also could provide high nonlinearity, which is favorable for the cross coupling between the two orthogonal polarization components. It was worth to mention that it is the first time to obtain the polarization domain wall solitons in a mode locked fiber laser.
We demonstrated the formation of noise-like square-wave pulses in an Er-doped fiber laser, using a microfiber based topological insulator as a saturated absorber (SA). The SA guaranteed both excellent saturable absorption and high nonlinearity. The pulse width can be increased ranging from 0.985 to 5.503 ns by increasing the pump power from 212 to 284 mW with the polarization state fixed. Moreover, with the adjustment of the polarization controllers in the cavity, the pulse width can be adjusted obviously. Worth mentioning, it was the first time that the noise-like square-wave pulse formed in a microfiber based topological insulator fiber laser.
We experimentally generated the duration-controllable square-wave pulse from an L band dissipative soliton (DS) fiber laser based on the dispersive Fourier transformation (DFT) technique. The rectangular spectrum emitted from an L band dissipative soliton fiber laser is mapped into a time-domain coherent rectangular waveform through the DFT technique. The duration of the square-wave pulse can be controllable with the adjustments of the pump power. The results demonstrate that it is an effective and flexible way to achieve duration-controllable square-wave pulses by combinating with DFT technique and DS fiber laser.
We have experimentally investigated supercontinuum generated by using different pulse dynamics patterns as the
pump pulses. These patterns, which include conventional mode-locked single pulse, condensed phase pulses and
pulsed bunches, were all directly produced from a mode-locked erbium-doped fiber laser based on a multi-layer
graphene saturable absorber. The strong third-order optical nonlinearity of graphene and all fiber cavity
configuration led to the multi-pulses operation states at a low pump power. A flat supercontinuum with 20-dB width
of 550 nm from 1200 nm to 1750 nm have all been obtained by seeding the amplified conventional mode-locked
single pulse and condensed phase pulses into a segment of photonic crystal fiber. On the other hand, experimental
results also show that the pulsed bunches was not conducive to form a flat supercontinuum.
We have experimentally observed bright-dark soliton pairs in an erbium-doped fiber ring laser for the first time. This approach is different from the vector dark domain wall solitons which separate the two orthogonal linear polarization eigenstates of the laser emission. In our laser, the bright-dark soliton pairs can co-exist in any one polarization state. Numerical simulations based on the coupled complex Ginzburg-Landau equations have confirmed the experimental results.