70 nm, broadly tunable passively Q-switched thulium-doped fiber laser with few-layer Mo0.8W0.2S2 saturable absorber

In this work, a thin Mo0.8W0.2S2 film is proposed and fabricated for the use as a saturable absorber (SA) in a thulium-doped fiber laser (TDFL) cavity. The few-layer Mo0.8W0.2S2 nanoparticles are obtained through hydrothermal exfoliation as a thin film and suspended in a polymer host, which is then placed between two fiber ferrules to serve as an SA. The proposed laser is capable of generating outputs with a maximum repetition rate of 65.79 kHz and a minimum pulse width of 1.84 mu s at the maximum pump power of 168.92 mW, as well as pulse energies andpeak powers as high as 35.73 nJ and 13.92 mW. The laser also has a broad tuning output from 1927.2 nm to 1996.8 nm, giving a tuning band of about 70 nm. The generated pulses are stable with a signal-tonoise ratio of 50.0 dB. The proposed laser has a high potential for operation near the 2000 nm wavelength region, with multiple bio-medical and sensing applications.