ZrGeTe4 Nanoparticles as a Saturable Absorber for Mode-Locked Operations at 1 and 1.55 µm

In the current paper, the nonlinear absorption characteristics and laser modulation performance of the ternary anisotropic semiconductor material ZrGeTe4 were successfully explored. The recovery time of the ZrGeTe4-PVA thin film was measured to be 5.74 ps by the pump–probe technology. By employing ZrGeTe4 as a saturable absorber, a passive mode-locked Yb-doped fiber laser was demonstrated for the first time. In the 1 µm mode-locked operation, the central wavelength was 1031.29 nm, the pulse repetition rate was 24.85 MHz, and the pulse width was 786.3 ps. In an Er-doped fiber laser operating at a wavelength of 1561.10 nm, the pulse width was as short as 1.26 ps with a repetition rate of 4.38 MHz. The results show that ZrGeTe4 has excellent broadband nonlinear optical characteristics.