Broadband few-layer niobium carbide MXene as saturable absorber for solid-state lasers

Abstract Recently, niobium-carbide (Nb2C) nanosheets, a member of MXene family, have gained significant attention because of their unique physical and chemical properties. Here, the few-layer Nb2C nanosheets were synthesized by a combination of selective etching and liquid cascade centrifugation. The broadband absorption properties of the few-layer Nb2C nanosheets were systematically investigated by the open-aperture Z-scan technique. The results indicate the excellent saturable absorption responses of Nb2C nanosheets, revealing the promising optical modulate application of Nb2C in solid-state lasers. Using the Nb2C saturable absorber (SA), passively Q-switched solid-state lasers from visible to near-infrared range were realized, which presented a promising alternative for a broadband optical modulator. Furthermore, a passively mode-locked laser at 1.06 μm was successfully achieved based on the Nb2C SA. A pulse duration of 13.5 ps was produced with the maximum average output power of 426 mW and a repetition rate of 99.1 MHz. To the best of our knowledge, this is the first time to use Nb2C nanosheets as a broadband SA for the solid-state lasers. The results may promote further applications of 2D optoelectronic materials from visible to near-infrared range.