Study of complex instability in a Thulium-doped figure-eight fiber laser including a polarization-imbalanced NOLM with no polarization control

• Published in: Optik (Stuttgart) 2024-12, Vol.318, p.172100, Article 172100
• Main Authors: Rodríguez-Morales, L.A., Pottiez, O., Armas-Rivera, I., González-Vidal, L.M., Durán-Sánchez, M., Hernández-Arriaga, M.V., Bello-Jiménez, M., Lauterio-Cruz, J.P., Ibarra-Villalon, H.E., Hernandez-Garcia, J.C.
• Format: Article
• Language: English
• Subjects: Mode-locked laser; Nonlinear polarization rotation; Pulse formation process; Q-switched-like; Quasi-continuous-wave regime; Quasi-mode-locked regime; Real-time measurements
• ISSN: 0030-4026
• DOI: 10.1016/j.ijleo.2024.172100

This study proposes a Thulium-doped figure-eight (F8) fiber laser design to be used as a platform to explore complex dynamics in passively mode-locked fiber laser systems. The proposed scheme incorporates a polarization-imbalanced nonlinear optical loop mirror (PI-NOLM) without a polarizer in the ring section. The absence of a polarizer prevents controlling the polarization state at the PI-NOLM input, which in turn allows the PI-NOLM switching power to vary dynamically during the laser operation. This leads to an intermittent noise-like pulse (NLP) operation, which is affected by complex instability in the form of non-periodic Q-switched-like behavior. Using real-time time-domain mapping techniques, we get a deep insight into the laser intricate dynamics, which involves not only NLPs, but also solitons and quasi-continuous-wave components with their subtle interactions. This study highlights the importance of the PI-NOLM in F8 laser schemes for the study and understanding of complex dynamics in Thulium-doped fiber lasers, which have been less extensively studied compared to other rare-earth-doped lasers. Our findings will contribute to the optimization and design of advanced laser systems for various scientific and industrial applications.