Tm-doped all-fiber structured femtosecond laser mode-locked by a novel Chem-Te saturable absorber.

• Succeeded in synthesizing the novel tellurium nanocrystal (Chem-Te) thin film. • Adopting this material as a SA for realization of all-fiber structured mode-locking at 2 μm-band. • Observed the harmonic mode-locked pulse trains and the obtained stable femtosecond level pulses output. We succeed in developing a chemically synthesized tellurium nanocrystals (Chem-Te) thin film by liquid phase peeling technique, and demonstrate this material is an effective saturable absorber (SA) for realization of stable mode-locking in an all-fiber structured thulium-doped laser cavity. By integrating this SA into an all-fiber structured ring laser cavity, we obtained the mode-locked pulses at the repetition rate of 11.17 MHz, the achieved pulses spectral bandwidth FWHM (full width at half maximum) of 5.26 nm and the pulses duration of 890 fs with 620 mW pump power at 1560 nm, the fundamental mode-locked laser output power as high as 5.35 mW. In addition, by further increasing the pump power, the second-order and third-order harmonic mode-locked pulses train of this fiber laser were also observed. To the best of our knowledge, this is the first report on the novel Chem-Te material saturable absorption property realization in 2 μm-band fiber laser system. [ABSTRACT FROM AUTHOR]