Abstract: Nanomaterials with promising optical, mechanical and electrical properties have garnered significant interest in photonics and electronics. However, the integration of nanomaterials with diverse characteristics for potential ultrafast photonics applications has emerged as a focal point. In this study, two-dimensional MXene (Ti₃C₂T_x) and CuO nanoparticles were synthesized to create heterostructure materials. The surface morphology, chemical composition and nonlinear absorption properties of the heterostructure materials were investigated. First-principle-based theoretical calculations were performed to explore the electronic and optical properties of the Ti₃C₂T_x/CuO heterojunction, offering insights into its essential properties and supporting the potential optoelectronic applications. Importantly, the Ti₃C₂T_x/CuO heterojunction effectively functioned as saturable absorbers in ultrafast lasers. Incorporating the Ti₃C₂T_x/CuO-based saturable absorber into a net-anomalous dispersion fiber cavity generated stable conventional-soliton pulses with duration of 495 fs. Additionally, adjusting cavity dispersion to net-normal allowed the Ti₃C₂T_x/CuO-based saturable absorber to generate dissipative soliton with a pulse width of 22 ps. The performance of Ti₃C₂T_x/CuO-based fiber lasers demonstrates enhancements over previous works. This study confirms that the Ti₃C₂T_x/CuO heterojunction is a promising nonlinear optical material for ultrafast applications and advanced MXene-based photonic devices.

Key words: MXene, Heterostructure, Fiber lasers, Saturable absorbers, Ultrafast photonics