A tunable L-band dissipative soliton (DS) fiber laser with nonlinear polarization rotation (NPR) playing the roles of both a saturable absorber (SA) and a tunable filter has been demonstrated experimentally and numerically. By appropriate adjustment of the states of the polarization controllers (PCs) and the pump power, DSs with continuously tunable wavelengths have been observed over the wavelength range from 1583.0 to 1602.4 nm with a 3-dB spectral bandwidth of around 20 nm and from 1581.9 nm to 1602.6 nm with a 3-dB spectral bandwidth of around 4 nm. In addition, we have observed that by increasing the pump power, the 3-dB spectral bandwidth of the DS could be increased without pulse breaking. Numerical results for the characteristics of the DSs are in accord with the experimental data.

The pulse dynamics of a self-starting Yb-doped fiber Mamyshev oscillator without external seed pulses or additional starting arms is demonstrated experimentally. Multiple dynamic patterns of pulses, including single pulses, bound-state pulses, and harmonic mode-locking pulses, are observed at different pump powers and filter spectral separations. The generation and evolution of bound states have also been simulated by establishing the corresponding theoretical model. This is the first systematic theoretical and experimental study of the formation and evolution of bound states in Yb-doped Mamyshev oscillators. The numerical results are in excellent agreement with experiment results, providing validation of both the measurements and the numerical model.

No abstract

We have experimentally demonstrated tunable multi-wavelength bright-dark and dark-bright pulse pairs in an all normal dispersion Yb-doped fiber laser (YDFL) with a long cavity configuration. By carefully adjusting the pump power and the polarization state, bright-dark pulse pairs could be converted into dark-bright pulse pairs at the same wavelength. The comb filter provided by the tapered fiber facilitated the formation of the multi-wavelength pulses. And the wavelength-tunable for both bright-dark pulse pairs and dark-bright pulse pairs could be achieved by using a tapered fiber and rotatable polarization controller in the cavity to control the cavity losses. The tunable ranges were 14 nm and 4 nm with wavelength spacings of~3.5 nm and~3.7 nm for dual-wavelength pulse pairs and triple-wavelength pulse pairs, respectively.

Noise-like pulse (NLP) can split and then self-assemble into dynamic bound states, named NLP polymer. Here, we reported the first observation, to the best of our knowledge, of the buildup process of bound NLPs in all-normal-dispersion Yb-doped fiber lasers. By designing two NLP fiber lasers, the distinct autocorrelation trace property for the bound NLPs with a short time interval (around 30 ps), and the high-speed oscilloscope trace characterization for the bound NLPs with a relatively broad time interval (∼500 ps) have all been exhibited. Also, we have demonstrated that it was the Raman effect that mediated the NLP bound states. The experiment results showed that though the inter-interval between the NLPs and the NLP width in the bound states are constantly changing, the envelope of each NLP remained localized and the bound NLPs could maintain within a wide pump range. The dynamics of the experimentally observed bound NLPs have also been discussed with fitting models and numerical simulations. In addition, the experimental test results for the coherence of the NLPs and their bound states further indicated that the NLPs had low temporal coherence characteristics.