H. Ahmad, N.A.M. Rusni, M.Z. Samion
This study investigates the performance of azulene and azulene-PEG as saturable absorbers (SAs) to induce mode-locked pulses in thulium-holmium-doped fiber lasers (THDFLs). The incorporation of polyethylene glycol (PEG) with azulene significantly enhances stability and optical performance. Key findings include improved linear absorption by 256 %. The nonlinear optical properties such as modulation depth, and saturation intensity of azulene-PEG are higher compared to azulene. Stability tests showed that azulene-PEG maintained mode-locked operation for up to 2 days, compared to 5 h for azulene. The laser efficiency of azulene-PEG was higher at 3.38 % compared to 2.84 % for azulene. These results indicate that azulene-PEG is a promising new class of saturable absorbers for ultrafast photonic applications, offering advantages in stability and performance over pristine azulene. This study contributes to the development of organic-based saturable absorbers for next-generation ultrafast laser systems. © 2025 Elsevier B.V.
Photonics Research Centre, Universiti Malaya, Kuala Lumpur, 50603, Malaysia; Physics Department, Faculty of Science, Universiti Malaya, Kuala Lumpur, 50603, Malaysia; Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Negeri Malang, Jalan Semarang 5, Malang, 65145, Indonesia
