Harith Ahmad, Leela Wanti Lohano, Bilal Nizamani
A narrow linewidth single longitudinal mode (SLM) tunable dual-wavelength fiber laser (DWFL) was experimentally demonstrated in this work. The dual-wavelength operation, with wavelengths of 1547.04 nm (λ1) and 1547.12 nm (λ2) at a free spectral range of 0.08 nm was achieved by integrating a compact and cost-efficient in-line Fabry-Perot interferometer (FPI). The SLM operation was realized by using a compound dual ring cavity (C-DRC) filter and unpumped erbium-doped fiber as a saturable absorber (SA). The mode selection capability of the C-DRC filter and SA was examined experimentally. The narrow linewidth SLM DWFL was obtained with a high optical signal-to-noise ratio of about 77 dB, which exhibits power fluctuations of about ±0.6 dB and wavelength drifts of around ±0.02 nm for 12 h duration. Wavelength tunability was demonstrated up to 1.5 nm by adjusting the temperature of the in-line FPI. The linewidths of λ1 (392 Hz) and λ2 (410 Hz) were measured using a delayed self-heterodyne interferometry system. Integrating the C-DRC filter and SA with the compact in-line FPI provides an ultra-narrow linewidth dual-wavelength output, offering a robust solution for advanced photonic applications such as fiber sensing and microwave generation. © 2025 The Author(s). Published by IOP Publishing Ltd.
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
