We report on the first experimental observation of dark-bright and dark-dark vector solitons in a highly birefringent cavity of all-normal-dispersion ytterbium-doped fiber laser. With the usage of different length of polarization maintaining fibers in the cavity, totally four types of vector solitons with different features were observed.

We report on the generation of high-energy noiselike pulse in a passively mode-locked thulium-doped fiber ring laser based on the nonlinear polarization evolution technique. A newly developed heavily thulium-doped germanate glass fiber was used as the gain medium. By properly rotating the polarization controllers, the 17.3 nJ noiselike pulse with 60.2 nm spectral bandwidth was obtained at the fundamental pulse repetition frequency of 6.37 MHz. Correspondingly, the maximum average output power was 110 mW. The direct output of high-energy noiselike pulse from the thulium-doped fiber laser provides a good candidate of pulse source for some important applications such as the supercontinuum generation at mid-infrared wavelength range and optical metrology.

A passively Q-switched thulium-doped fiber (TDF) laser based on the nonlinear polarization evolution technique was demonstrated with the central wavelength of 1898.4 nm. With the increasing pump power, the pulse repetition frequency of the Q-switched TDF laser from 87.6 to 110.1 kHz was achieved, while the corresponding pulse duration was changed from 1171 to 785.7 ns. The power instability of the TDF laser was measured to be about ±1.5% during 8 h. In addition, the mode-locked phenomenon was also observed in our all-fiber TDF laser by carefully adjusting the polarization controllers.

A simple scheme of switchable dual-wavelength passively mode-locked fiber laser is demonstrated. The laser can be flexibly switched among different mode-locked states simply by tuning the cavity loss while keeping all the other cavity parameters fixed. As the cavity loss increases, the mode-locked fiber laser operates at the long-wavelength, dual-wavelength, and short-wavelength states, successively. In addition, these states can be conveniently switched without losing the mode-locked operation and the switching process is reversible as the cavity loss decreases. The mechanism is qualitatively explained by the balance between the fiber gain and the cavity loss.