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arXiv · 2511.23360

Optical bistability of continuous-wave and multi-pulse phase transition within EDFL via low threshold saturable absorber

Hsuan-Sen Wang·Wen-Hsuan Kuan·Ahmed F. M. El-Mahdy·Gong-Ru Lin·Kuei-Huei Lin·Shiao-Wei Kuo·Chao-Kuei Lee
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Abstract

We demonstrate optical bistability in an erbium-doped fiber laser (EDFL) using a low saturation intensity covalent organic framework (COF) saturable absorber (SA). The COF-SA satisfies the free-energy criterion for bistability, enabling switching among non-lasing, continuous-wave, and mode-locking states. Two optical bistability regions are observed, including a distinctive direct mode-locking to non-lasing transition during pump down-sweep, absent in previous EDFL studies. Stable soliton-like pulses and stepwise pulse-number hysteresis further indicate first-order phase-transition-like dynamics. These results show that low-saturation intensity SAs offer a compact route to bistability-assisted pulse formation in fiber lasers.

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Hsuan-Sen Wang, Wen-Hsuan Kuan, Ahmed F. M. El-Mahdy, Gong-Ru Lin, Kuei-Huei Lin, Shiao-Wei Kuo, Chao-Kuei Lee. 2025-11-28. Optical bistability of continuous-wave and multi-pulse phase transition within EDFL via low threshold saturable absorber. https://arxiv.org/abs/2511.23360

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