An Qi, Norazriena Yusoff, Wu Yi Chong, Harith Ahmad
With layered structures, broadband absorption, and strong nonlinear responses, MXenes, combined with transition metal oxides possessing tunable structures and oxidation states, hold promise for developing hybrid nonlinear materials. Capitalizing on the synergistic properties of its constituents, a Nb₂CTx–TiO₂/PVA composite thin-film saturable absorber (SA) was prepared by a solution-processed method. The fabricated film exhibited nonlinear optical parameters with a modulation depth of 88 % and a saturation intensity of 0.1 MW/cm². UV-Vis experiments revealed that the band gap decreased from 1.57 eV in MXene to 1.33 eV in the new composite. Incorporating this film into a laser cavity enabled passive Q-switched pulsed generation in the C-band near 1.55 μm. At a pump power of 281.84 mW, the laser produced stable pulses centered at 1557.8 nm, with a spectral width of 2.60 nm, a pulse duration of 1.87 μs, and a repetition rate of 53.3 kHz. A high signal-to-noise ratio exceeding 52 dB and a wavelength tunability of 46 nm were also achieved. This work highlights the significant potential of the Nb₂CTx–TiO₂/PVA composite in nonlinear optics and ultrafast photonic applications. © 2025
Department of Physics, Faculty of Science, Universiti Malaya, Kuala Lumpur, 50603, Malaysia; Photonics Research Centre, Universiti Malaya, Kuala Lumpur, 50603, Malaysia; Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Negeri Malang, Jalan Semarang 5, Malang, 65145, Indonesia
