Wavelength-switchable dual-wavelength pulse emission from a practical-filter-free all-fiber ring cavity

We proposed the emission of wavelength-switchable dual-wavelength-comb pulses in a practical-filter-free cavity. Based on the polarization dependent loss based gain profile tuning, lasings in triple independent gain subregions, i.e. ~1530-, ~1543- and ~1555-nm gain subregions, of erbium-doped fiber, are experimentally observed. Mode-locked by hybrid mechanisms combining carbon nanotube and nonlinear polarization evolution, triple types of dual-wavelength pulses distributed in different dual gain subregions are experimentally obtained. They are distributed in above triple gain subregions and could be switched by adjusting the intracavity polarization controller. These results provide a simple yet effective route to obtain dual-wavelength-comb pulses without additional practical filter and show the high potential in the applications of single-cavity dual-comb metrology.