分布式侧面耦合包层泵浦光纤激光器研究

发布时间：2018-05-27 07:11

本文选题：光纤激光器 + 分布式侧面耦合包层泵浦光纤　；参考：《国防科学技术大学》2015年博士论文

【摘要】：高功率光纤激光器在材料精密加工等工业制造和国防军事领域都有重要的应用,是近年来国际上的研究热点。尽管常规双包层光纤推动了高功率光纤激光器的发展,但是其功率的进一步提升面临重大挑战;而分布式侧面耦合包层泵浦(Distributed Side-Coupled Cladding-Pumped,DSCCP)光纤是一种有望突破限制,实现功率进一步提升的新型光纤。然而相关研究的国际报道极为有限,国内的研究报道几近空白。因此,论文基于分布式侧面耦合包层泵浦光纤传输特性的研究,设计和研发分布式侧面耦合包层泵浦光纤,并通过实验验证该光纤在高功率光纤激光器中的表现。首先,介绍了弱耦合近似下两波导之间模耦合系数的求解;数值模拟分析了泵浦光在分布式侧面耦合包层泵浦光纤中的耦合传输特性,给出了泵浦光在不同结构光纤之间的耦合过程,讨论了强耦合与弱耦合之间的不同,分析了缠绕对泵浦光耦合吸收的影响;建立了简化的泵浦光耦合传输模型,给出了估计综合平均耦合系数的方法,并详细分析了泵浦光的耦合传输特性和规律。其次,根据分布式侧面耦合包层泵浦光纤中的泵浦光耦合传输特性建立了分布式侧面耦合包层泵浦光纤激光器稳态速率方程模型,并对方程进行了近似解析求解和数值计算模拟;详细分析了分布式侧面耦合包层泵浦光纤激光器的特性及影响因素,并从出光效率和热效应两方面与常规双包层光纤激光器进行对比研究。结果显示,经过优化设计可以使分布式侧面耦合包层泵浦光纤激光器在保持与常规双包层光纤激光器同样高效率的同时具有较大的热管理优势。最后,基于自主设计并研制的分布式侧面耦合包层泵浦光纤进行高功率光纤激光器的实验验证。利用直径10/125-125的分布式侧面耦合包层泵浦光纤,在国内首次实现了该种光纤107W斜率效率51.3%的放大器输出,并论证了基于分布式侧面耦合包层泵浦光纤双端泵浦的可行性;利用直径30/250-250的分布式侧面耦合包层泵浦光纤,提出了级联放大方案并获得了两级放大的1009W光纤放大器输出,在国内首次验证了分布式侧面耦合包层泵浦光纤级联放大的千瓦量级系统的可行性。此外,还验证了分布式侧面耦合包层泵浦光纤高功率振荡器实验,获得了1519W斜率效率64.6%的波长为1080nm振荡器输出;探索了1018nm光纤激光级联泵浦分布式侧面耦合包层泵浦光纤放大器实验,获得了118.7W,斜率效率75.6%的放大输出。基于现有实验条件,分别用LD直接泵浦和光纤激光级联泵浦的方式设计了两套万瓦级光纤激光器,模拟结果显示它们都具有输出万瓦高功率光纤激光的能力。
[Abstract]:High power fiber laser has been widely used in industrial manufacturing, military defense and so on. It is a hot research topic in the world in recent years. Although conventional double-clad fiber has promoted the development of high-power fiber lasers, the further improvement of its power faces major challenges, while the distributed Side-Coupled cladding-pumped DSCCP-fiber is a promising breakthrough. A new type of fiber for further power enhancement. However, the international reports of related studies are very limited, and the domestic research reports are almost blank. Therefore, based on the study of the transmission characteristics of the distributed side-coupled cladding pumped fiber, the distributed side-coupled cladding pumped fiber is designed and developed, and the performance of the fiber in the high-power fiber laser is verified by experiments. First of all, the solution of mode coupling coefficient between two waveguides under weak coupling approximation is introduced, and the coupling propagation characteristics of pump light in distributed side-coupled cladding pumped fiber are analyzed numerically. The coupling process of pump light between different fiber structures is given, the difference between strong coupling and weak coupling is discussed, the influence of winding on the coupling absorption of pump light is analyzed, and a simplified coupling transmission model of pump light is established. A method for estimating the combined average coupling coefficient is presented, and the coupling propagation characteristics and rules of the pump light are analyzed in detail. Secondly, the steady state rate equation model of the distributed side-coupled cladding pumped fiber laser is established according to the characteristics of the pump optical coupling propagation in the distributed side-coupled cladding pumped fiber. The equation is solved by approximate analysis and numerical simulation, and the characteristics and influencing factors of distributed side-coupled cladding pumped fiber laser are analyzed in detail. The optical efficiency and thermal effect are compared with conventional double-clad fiber lasers. The results show that the distributed side-coupled cladding pumped fiber laser can keep the same efficiency as the conventional double-clad fiber laser and has the advantage of thermal management. Finally, the experimental verification of high power fiber laser is carried out based on the distributed side-coupled cladding pumped fiber designed and developed by ourselves. The 107W slope efficiency of the 107W fiber is first achieved by using the distributed side-coupled cladding pumped fiber with a diameter of 10 / 125-125, and the feasibility of double-end pumping based on the distributed side-coupled cladding pumped fiber is demonstrated. Using distributed side-coupled cladding pumped fiber with diameter of 30 / 250-250, a cascade amplification scheme is proposed and the output of 1009W fiber amplifier with two amplifiers is obtained. The feasibility of the distributed side-coupled cladding pumped fiber cascade amplification system is verified for the first time in China. In addition, the experiment of distributed side-coupled cladding pumped fiber high power oscillator is verified. The wavelength of 1519W slope efficiency of 64.6% is output of 1080nm oscillator. The experiment of 1018nm fiber laser cascade pumped distributed side-coupled cladding pumped fiber amplifier has been carried out. The amplification output of 118.7 W and slope efficiency of 75.6% has been obtained. Based on the existing experimental conditions, two sets of optical fiber lasers are designed by LD direct pumping and fiber laser cascade pumping, respectively. The simulation results show that both of them have the ability to output high power optical fiber lasers.
【学位授予单位】：国防科学技术大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TN248

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