Flat-Top Soliton Frequency Comb Generation Through Intra-Cavity Dispersion Engineering in a Brillouin Laser Cavity

• Published in: Journal of lightwave technology Vol. 41; no. 6; pp. 1820 - 1833
• Main Authors: Zhang, Xucheng, Jia, Zhixu, Huang, Yali, Wu, Jiliang, Wang, Ting, Chen, Yuxian, Yu, Yongsen, Yang, Yuede, Xiao, Jinlong, Qin, Weiping, Huang, Yongzhen, Qin, Guanshi
• Format: Journal Article
• Language: English
• Published: New York IEEE 15.03.2023; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Brillouin fiber laser cavity; Dissipation; dissipative Kerr cavity soliton; Efficiency; Fiber lasers; Fiber nonlinear optics; flat-top optical frequency comb; Four-wave mixing; Group velocity; high conversion efficiency; Holes; intra-cavity dispersion engineering; Lasers; Longitudinal waves; Nonlinear optics; Optical fiber dispersion; Optical fibers; Optical frequency; Optical solitons; Pulse compression; Scattering; Solitary waves; Waveforms
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/JLT.2022.3226782

Dissipative Kerr cavity soliton and optical frequency comb (OFC) can be generated in fiber cavities or microresonators with anomalous group velocity dispersion (GVD), which has achieved great breakthroughs and found significant applications in many fields. Despite recent progress in this field, it remains challenging to obtain OFCs with a flat-top spectrum and a high conversion efficiency in an optical cavity with anomalous GVD. In this paper, intra-cavity dispersion engineering is proposed to reshape the bright dissipative Kerr solitons in a Brillouin laser cavity with anomalous GVD for generating flat-top OFCs with a high conversion efficiency. By introducing a piece of optical fiber with normal GVD into the above Brillouin fiber laser cavity for making a hybrid fiber cavity with near zero net cavity GVD, the intra-cavity waveform is broadened in time-domain due to the existence of normal GVD, which conquers the pulse compression caused by four-wave mixing and anomalous GVD, and leads to the formation of bright dissipative Kerr solitons and OFCs with a flat-top profile and a high conversion efficiency, via interlocking of up-switching waves. Furthermore, flat-top OFCs with step tunable mode spacing from GHz to THz are achieved via intra-cavity dispersion engineering.