Khalil Kamaruzzaman, Harith Ahmad, Suresh Sagadevan, Mousa Hussein
Ultrashort pulse generation in holmium-doped fiber lasers (HDFLs) employing a CQDs/g-C3N4/TiO2 composite as a saturable absorber (SA) was demonstrated for the first time. The CQDs/g-C3N4/TiO2 SA was fabricated by a simple drop-casting technique onto an arc-shaped fiber, forming an efficient SA for pulse initiation. The oscillator produced stable soliton-like pulses centered at 2082 nm, with a pulse width of 1.59 ps and a repetition rate of 15.61 MHz. The enhanced nonlinear absorption of the CQDs/g-C3N4/TiO2 structure arises from synergistic interfacial coupling between carbon quantum dots, TiO2, and g-C3N4, which promotes rapid carrier dynamics and broad spectral response. The results verify that this ternary nanocomposite provides sufficient nonlinear optical modulation for stable pulse formation across the extended 2 μm region, expanding the applicability of semiconductor–oxide composites for ultrafast photonics. © 2026 Elsevier B.V.
Institute of Advanced Studies, Advanced Studies Complex, Kuala Lumpur, 50603, Malaysia; Photonics Research Centre, Universiti Malaya, Kuala Lumpur, 50603, Malaysia; Department of Physics, Faculty of Science, Universiti Malaya, Kuala Lumpur, 50603, Malaysia; Adjunct Professor, Department of Physics, Universitas Negeri Malang, Malang, 65145, Indonesia; Nanotechnology & Catalysis Research Centre, Universiti Malaya, Kuala Lumpur, 50603, Malaysia; Department of Electrical and Communication Engineering, United Arab Emirates University, Al Ain, United Arab Emirates
