H. Ahmad, M.W.K.M.F. Yasmin, M.A.M. Lutfi, M.K.A. Zaini, M.Z. Samion, S. Sagadevan, N.A.M. Rusni, K. Thambiratnam, Z. Mahmoodin, S. Sun
There is a growing demand for ultrashort fiber lasers at 2.0 µm due to their important role in cutting-edge fields such as spectroscopy, clinical surgery, and optical telecommunications. While standard two-dimensional (2D) materials are widely used as passive saturable absorbers (SAs), their performance is often limited by low modulation depths and structural degradation, such as oxidation. To overcome this, a novel ternary nanocomposite of g-C₃N₄/MXene/Co₃O₄ was fabricated and integrated into a mode-locked thulium-doped fiber laser (TDFL) cavity as a highly efficient SA. Nonlinear optical characterization of the integrated SA shows a higher modulation depth of 20.3% and a high saturation intensity of 39.4 MW/cm². It produced ultrashort 1.3 ps pulses at 1927.8 nm and a fundamental repetition rate of 17.67 MHz. The cavity demonstrates outstanding long-term operational stability, with minimal spectral or temporal drift over a continuous 300-minute observation period and a signal-to-noise ratio (SNR) of 44.3 dB. These results establish that the g-C₃N₄/MXene/Co₃O₄ nanocomposite has the potential to serve as an optical modulator for advancing ultrafast nonlinear photonics in the mid-infrared regime. © 2026 Elsevier B.V.
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; Universiti Kuala Lumpur British Malaysian Institute (UniKL, BMI), Batu 8, Jalan Sungai Pusu, Selangor, 53100, Malaysia; Nanotechnology& Catalysis Research Centre, Universiti Malaya, Kuala Lumpur, 50603, Malaysia; Physics Dept., Kulliyyah of Science, International Islamic University Malaysia, Bandar Indera Makhota, Kuantan, 25200, Malaysia; School of Mechanical and Automotive Engineering, University of Technology, Qingdao, 266520, China
