基于石墨烯的中红外高功率调Q光纤激光器基础研究

High power mid-infrared Q-switched fiber lasers have attracted significant attentions because of their numerous applications in scientific research, military, biomedical treatment and civil areas. However, the current mid-infrared Q-switched fiber lasers’ output powers and pulse energies are olny at mW and nJ/several µJ level, respectively, which makes them still at a primary stage. In this project, three key physical mechanisms in 3µm high power graphene Q-switched Er3+-doped fluoride fiber laser will be systematically investigated. The dependence of the Q switched performances on the graphene layers and uniformity, etc, will be studied. A physical model of multistage pulses amplification system will be established. Instantaneously pulses pumped 3-dementional heat transmission model in the fiber will be established, the heat deposition mechanism will be revealed and techniques to physically reduce the heat deposition and thermal gradient will be explored. Experimental optimization will be performed based on the theoretical study to improve the laser efficiency and output power..The heat deposition, efficiency and output power enhancement of the multistage amplification system are common issues when comes to mid-infrared high power fiber lasers, the project results have good portabilities. This project will promote the development of the mid-infrared high power Q-switched fiber laser technique.

高功率中红外波段调Q光纤激光器在科研、军事、生物医疗及民用等领域具有广泛应用前景，是国内外研究的热点。然而目前中红外调Q光纤激光器的输出功率多在mW量级，脉冲能量仅为nJ或几µJ，还处于较初级的阶段。本项目拟针对功率水平提高的三个关键物理机制问题，对基于石墨烯的3µm高功率调Q 光纤激光器展开系统研究。拟揭示石墨烯层数、均匀度等特性对中红外调Q性能的影响；建立多级脉冲功率放大系统物理模型；针对高功率运转下的关键热沉积问题，建立瞬态脉冲泵浦下光纤内三维热传导模型，揭示热沉积机理，探索从物理机制上减少热沉积及去热梯度制冷方法；结合理论优化实验设计提高激光效率及输出功率。.本项目拟解决的高功率下光纤内的热沉积问题及功率放大系统的效率及功率水平提高的问题等是中红外波段实现高能脉冲的共性问题，研究结果具有良好的移植性。项目的开展将促进中红外高功率调Q光纤激光技术的发展。

中红外高功率脉冲光纤激光在光谱学、生物医疗、军事、材料加工等诸多领域具有重要应用前景，鉴于上述领域对高性能中红外高功率脉冲光纤激光源的迫切需求，在本项目的资助下，我们围绕中红外高功率脉冲光纤激光，开展了以石墨烯为代表的二维材料-过渡金属硫化物等的中红外波段可饱和吸收特性研究，较为领先地从实验上证实了过渡金属硫化物WS2、碳纳米管CNT在3微米中红外波段的非线性吸收特性，并应用于中红外光纤激光器中实现稳定调Q及锁模脉冲输出。同时，我们开展了基于Fe2+:ZnSe晶体的高功率可调谐被动调Q中红外光纤激光关键技术的研究，在90 nm的中红外波段范围内实现了高功率高能量的调Q脉冲光纤激光输出，最大输出功率和脉冲能量分别为5.16 W和27.7 μJ，据我们所知这是3 μm波段被动调Q脉冲光纤激光器的国际最高功率水平。此外，我们在实验上实现了中红外脉冲激光光纤放大器、中红外增益调制脉冲光纤激光、中红外多波段连续调谐锁模脉冲光纤激光等，并取得了一系列国际国内较为领先的成果。本项目不仅深化了对中红外脉冲光纤激光器和放大器的认识，还促进了高功率高脉冲能量中红外波段脉冲激光的多种潜在应用。基于上述研究成果，课题组发表国际学术论文13篇（SCI收录11篇，其中中科院SCI期刊分区一区论文2篇，二区论文6篇），项目负责人第一及通讯作者论文8篇，申请国家发明专利13项，其中已授权3项。