ZrGeTe₄ Nanoparticles as Saturable Absorber for Mode-Locking 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 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 is 1031.29 nm, the pulse repetition rate is 24.85 MHz, and the pulse width is 786.3 ps. In an Er-doped fiber laser operating at the wavelength of 1561.10 nm, the pulse width 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.