Narrowband Mode-Locked Fiber Laser via Spectral-Domain Intermodal Interference

• DOI: 10.1109/jlt.2021.3096132
• Publication Date: 2021-07-09T19:45:32Z
• Authors: Qun Gao; Yueqing Du; Zhiwen He; Dong Mao; Jianlin Zhao
• Keywords: 0202 electrical engineering, electronic engineering, information engineering; 02 engineering and technology; 7. Clean energy

We demonstrate a hybrid-structure fiber laser composed of single-mode fiber (SMF) and four-mode fiber (FMF), capable of delivering stable near-chirp-free soliton with the bandwidth of 75 pm. Ascribed to the spectral-domain intermodal interference, the SMF-FMF cavity serves not only as a ring resonator but also as an intrinsic spectral filter. The wavelength of the narrowband soliton is tunable within 10 nm by a polarization controller. Simulation results validate the experimental observations, revealing that the filtering effect simultaneously balances the self-phase modulation induced spectral broadening and saturable absorption induced temporal compression. The narrowband fiber laser is attractive for spectroscopy, quantum optics, and material processing, and offers a promising platform to study the evolution dynamics of few-mode solitons.