基于硫系拉曼光纤激光器的中红外耗散孤子研究

2-5 µm mid-infrared ultrashort pulse laser sources possess important applications in fields such as medicine, communication, national defense, and so on. However, the current mid-infrared ultrashort pulse fiber lasers are not perfect in operation wavelength range and output pulse performance. Therefore, high-performance new-wavelength mid-infrared ultrashort pulse fiber lasers are in urgent demand. Aim at this kind of mid-infrared fiber lasers, normal dispersion Raman fiber lasers are constructed by applying chalcogenide tapered fibers as Raman gain mediums, and dissipative soliton is generated by using two-dimension materials-based mid-infrared mode-lockers. Moreover, the saturable absorption characteristics of two-dimension materials and the internal effect mechanisms of the dispersion value and nonlinear coefficient of chalcogenide fibers, on the output performance of dissipative soliton are investigated. At last, high performance mid-infrared two-dimension materials-based mode-lockers will be fabricated, and the effective management on dispersion and nonlinear effects of mid-infrared dissipative soliton will be presented, as well as mid-infrared dissipative soliton will be achieved in normal dispersion chalcogenide glass Raman fiber lasers with the largest wavelength tunable range of 2.07-2.20 µm, the maximum pulse energy of 100 nJ and the narrowest pulse duration of 10 ps. The research of this project will lay a solid scientific foundation for the development of high-performance mid-infrared ultrashort pulse fiber laser sources with own intellectual property.

2-5 µm中红外超短脉冲激光源在医疗、通信、国防等领域具有重要应用前景。针对现有中红外超短脉冲光纤激光源新波长拓展及脉冲性能提升存在的局限性，本项目以发展高能量新波长中红外超短脉冲光纤激光源为契机，提出利用高拉曼增益的正色散硫系拉锥光纤与二维材料锁模器相结合，开展基于硫系拉曼光纤激光器的中红外耗散孤子研究，主要围绕探索二维材料中红外可饱和吸收性能对耗散孤子脉冲宽度的影响、研究光纤激光器腔内色散和非线性效应对耗散孤子脉冲性能的影响两个关键科学问题，旨在阐明其内在机理，并提出高性能中红外二维材料锁模器研制方案及有效的中红外耗散孤子色散和非线性效应管理方案，最终实现中心波长最大可调谐范围2.07-2.20 µm、最高单脉冲能量>100 nJ、最窄脉冲宽度<10 ps的中红外耗散孤子。本项目的实施将可为今后发展自主知识产权的中红外超短脉冲光纤激光器提供科学的依据和奠定坚实的基础。

近年来，随着激光技术的不断发展，超短脉冲激光器被广泛应用于工业、通信、医疗、军事和科研等领域。目前，超短脉冲激光器在近红外波段的发展相对成熟，在中红外波段稍显缓慢。然而，在许多应用场合，2-5 µm中红外超短脉冲激光器却具有独特的优势和特殊的地位。针对现有中红外超短脉冲光纤激光源新波长拓展及脉冲性能提升存在的局限性，本项目深入研究高性能中红外脉冲光纤激光器的产生方式。首先，通过采用包层泵浦技术提供大增益，结合大耦合比输出腔内激光的腔体优化，实现了基于拓扑绝缘体的波长宽带可调谐2 µm大能量光纤激光器。其次，利用高损伤阈值的模间拍频锁模技术结合腔体优化，实现了高转换效率的瓦级中红外脉冲光纤激光器。再次，利用UHNA4光纤调控掺铥光纤激光器色散和非线性效应，研究孤子脉冲的色散和非线性效应调控机制，成功实现不同类型的孤子脉冲输出。同时，通过自锁模和自相位调制非线性效应，实现了双频锁模的2 µm光纤激光器。而后，采用脉冲光泵浦源，研制脉冲型稀土离子掺杂和拉曼光纤激光器以及脉冲型中红外光纤放大器，分别获得高功率大能量的单脉冲、多脉冲可切换的光纤激光源和大能量的短脉冲拉曼光纤激光源以及高性能脉冲光纤放大器。最后，利用光纤端面抛光技术，研制高质量氟化物光纤和硫系光纤平斜端面，并成功实现异质光纤间的高功率效率耦合。通过上述研究内容，本项目已系统厘清锁模器参数、激光器腔体色散、非线性效应、增益介质、激光耦合输出比等参数对中红外脉冲激光性能的影响规律并提出了有效管理方案，同时实现了多台高性能的中红外脉冲光纤激光器，可为发展自主知识产权的中红外超短脉冲光纤激光器提供科学的依据和奠定坚实的基础。