阶跃光纤混合模的聚焦特性分析  

Analyzing the Focusing Properties of Mixed Modes in a Step-Index Fiber

作　　者：韩越 王挺峰[1] 巩盾 车东博 王铭 Han Yue;Wang Tingfeng;Gong Dun;Che Dongbo;Wang Ming(State Key Laboratory of Laser Interaction with Matter,Changchun Institute of Optics,Fine Mechanics and Physics,Chinese Academy of Sciences,Changchun 130033,Jilin,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院长春光学精密机械与物理研究所激光与物质相互作用国家重点实验室,吉林长春130033 [2]中国科学院大学,北京100049

出　　处：《激光与光电子学进展》2022年第17期92-97,共6页Laser & Optoelectronics Progress

基　　金：国家自然科学基金(61805234)。

摘　　要：在激光加工等领域常利用光纤激光的聚焦以获得高功率密度的光斑。为了分析阶跃光纤混合模的聚焦特性,基于广义惠更斯-菲涅耳衍射公式,数值计算了阶跃光纤中基模(LP01)与高阶线偏振模在非相干叠加和相干叠加两种情况下的聚焦光强分布。仿真分析了混合模相对于单一LP01模式的聚焦特性,研究了其聚焦光斑的平均功率密度、焦点偏移随模式占比、模式间相位差的变化规律。研究表明:当混合模非相干叠加时,随着基模占比的增加,聚焦光斑功率密度随之增加且焦点偏移减小;当混合模相干叠加时,基模占比及模间相位差都会影响聚焦效果,可以通过合理控制基模占比和模间相位差,达到聚焦光斑功率密度高于基模的聚焦光斑功率密度、减小混合模焦点偏移的目的。In laser processing and other fields,the focus of a fiber laser is often used to obtain a highpowerdensity spot.To analyze the focusing properties of mixed modes in a stepindex fiber,based on the generalized HuygensFresnel diffraction formula,this study numerically calculates the focusing intensity distribution of the incoherent and coherent superpositions of the fundamental(LP01)and highorder linear polarization modes in a stepindex fiber.The focusing properties of the mixed modes relative to the single LP01 mode are simulated and analyzed,and the change law of the average power density of the focused spot and focus shift is studied with the changing mode ratio and intermode phase difference.When the mixed modes are incoherently superimposed,with the increase in the fundamental mode ratio,the power density of the focused spot increases and the focus shift decreases.Moreover,when the mixed modes are coherently superimposed,the fundamental mode ratio and intermode phase difference affect the focusing effect.Therefore,we can achieve the purpose of focusing the spot power density higher than that of the fundamental mode and reducing the focus shift of the mixed modes by reasonably controlling the fundamental mode ratio and intermode phase difference.

关 键 词：光纤光学 光纤激光 混合模 平均功率密度 焦点偏移 

分 类 号：TN249[电子电信—物理电子学]