A passively mode-locked thulium-doped fiber laser based on a D-shaped fiber deposited with PbS nanoparticles

摘要

We demonstrate a passively mode-locked thulium-doped fiber laser through the utilization of PbS nanoparticles (NPs) with ultrafast pulse generation in this letter. The PbS NPs are deposited on a D-shaped fiber by the optical deposition method. The cavity shows a net dispersion of -0.781 ps(2). The central wavelength of the output spectrum is at 1930 nm with a 3 dB bandwidth of 3.2 nm. The pulse repetition is 19.74 MHz with the duration of 1.3 ps. The time-bandwidth product is calculated to be 0.35. The second- and third-order harmonics are observed with the increase of pump power. The bound solitons are also observed in the cavity when the pump power is higher than similar to 600 mW. The D-shaped fiber SA shows a damage threshold of higher than 3.5 kW. These results demonstrate that the PbS NPs are indeed an excellent material for passively mode locking in mid-infrared wavebands.