Tellurium-nanorod-based saturable absorber for an ultrafast passive mode-locked erbium-doped fiber laser

In this paper, we propose and demonstrate ultrafast Te nanorods as a saturable absorber (SA) for producing mode locking from an erbium-doped fiber laser for the first time, to the best of our knowledge. The Te nanorods were fabricated by a simple green chemical method with energy conservation and without a purification process. The morphology and structure measurements confirm uniform Te nanorods with a constant aspect ratio. The synthesized SA has a saturation intensity and modulation depth of $25.44\, {\rm MW/cm}^{2} $25.44MW/cm2 and 4%, respectively. By integrating the proposed SA into an erbium-doped all fiber-based ring cavity, the mode-locked fiber laser was readily generated. The conventional soliton pulses of ${3.56}\;{\rm ps}$3.56ps pulse width were obtained at 1566.7 nm central wavelength and a pulse repetition rate of 1.87 MHz. The results show that the moderate saturable-absorption characteristics of Te nanorods have superior performance in the ultrafast optics field, which is eligible in many applications, such as optical communications.