【作者】 张辉；

【导师】 宋清海；

【作者基本信息】 哈尔滨工业大学 ， 电子科学与技术， 2021， 硕士

【摘要】 涡旋光束因具有螺旋的等相位面、携带轨道角动量、且不同拓扑荷数之间正交等特性,在光学微操纵、光通信等方面具有重要作用。片上集成的微纳米级涡旋激光器是未来满足信息容量指数需求增长的关键元件,而对可调谐涡旋微激光器的研究,仍需要额外的多路复用才能实现不同的拓扑荷数改变。作为近些年半导体微纳材料研究热点之一,钙钛矿单晶因其优异的光学特性越来越受到研究人员的重视。但由于钙钛矿微米线横截面的方形微腔出射的回音壁模式（Whispering Gallery Mode,WGM）激光基本为线性偏振光,导致其在许多应用场合受到限制,对单个微型光源出射光场的精确调控也有待于进一步提高。超透镜具有超薄、超轻、低能耗,可对光波前相位灵活调控的优势,易用于光场调控的小型化与集成化。因此,本文提出将钙钛矿微米线与超透镜结合,利用超透镜对微米线激光器出射光场调控,实现相干涡旋激光阵列的出射。通过采用Pancharatnan-Berry相位与传输相位原理,在对超透镜的功能分析后设计得到能够实现拓扑荷数可控的超透镜,并通过数值计算软件验证其功能,表明自旋轨道转换能够使TiO₂超透镜将两个轨道角动量光束转换为具有相反圆偏振的相同衍射极限点。因此,可分解为两个圆偏振光的焦点处的激光在通过超透镜后准直为具有两个不同拓扑荷数的涡旋激光出射。通过引入离轴项,将这一概念推广到2?2的超透镜阵列,即可同时得到8个具有不同拓扑荷数的涡旋光出射。通过微纳制备加工工艺实现超透镜与超透镜阵列的制备,并搭建光路对制备得到的超透镜（阵列）进行光学性能表征,验证功能。钙钛矿微米线的制备通过溶液法实现,同样搭建光路实现其光学性能表征。在完成超透镜的设计、数值仿真验证、工艺制备、光学性能表征以及钙钛矿微米线的制备和光学表征之后,将二者结合,用倍频后的飞秒光泵浦微米线实现WGM光激射,通过在超透镜（阵列）出射端选择不同旋向的圆偏振光可得到不同拓扑荷数的涡旋光（阵列）出射。相对于传统生成涡旋激光阵列的方法,该方法在实现不同拓扑荷数涡旋激光出射的同时,能够保持时间相干性较好且集成度良好,为下一代的多维多路复用技术提供坚实的基础。更多还原

【Abstract】 Vortex beams play an important role in optical micromanipulation and optical communication and other fields because of the helical phase structure,orbital angular momentum and orthogonality between different topological charges.On-chip integrated micro-and nano-scale vortex lasers are key elements to address the exponentially growing demand for information capacity.While tunable vortex microlasers have been reported,each laser pulse still possesses a particular topological charge and additional multiplexing is required.As one of the research hotspots of semiconductor micro/nano materials in recent years,perovskite single crystal has attracted more and more attention because of its excellent optical properties.However,because the whispering gallery mode（WGM）laser emitted from the square microcavity of perovskite nanowires is basically linearly polarized,it is limited in many applications.The precise control of the light field emitted by a single micro light source needs to be further improvedMetalens has the advantages of ultra-thin,ultra-light,low energy consumption and flexible regulation of light wavefront phase.It is easy to be used for miniaturization and integration of light field modulation.By combining metalens with semiconductor microlaser,we demonstrate the simultaneous generation of coherent laser array with different topological charges.Based on the principle of Pancharatnan-Berry phase（PB phase）and transmission phase,metalens with controllable topological charge is designed after the functional analysis of the metalens,and its function is verified by numerical calculation.The spin-orbital conversion enables Ti O₂vortex metalens converting two orbital angular momentum beams into the same diffraction-limit spot with opposite circular polarizations.Consequently,the microlaser emission at the focal spot,that can be decomposed to two circularly polarized beams,shall be collimated to vortex laser beams with two different topological charges through the time-reversal process.By introducing the off-axis terms,this concept has been extended to a 2×2metalens array and 8 topological charges are produced simultaneously.The fabrication of metalens and metalens array are realized through micro-nano manufacturing process,and the optical set up is built to characterize the optical properties of the prepared metalens（array）and verify the function.Lead halide perovskite（Cs Pb Br₃）microwires were prepared by solution method,and the optical set up was also built to characterize their optical properties.After completing the design,numerical simulation,manufacturing process,optical performance characterization of the metalens,as well as the preparation and optical characterization of perovskite microwires,the two are combined to realize WGM optical lasing by pumping the microwires with frequency doubled femtosecond light.Vortex beam（array）with different topological charges can be obtained by selecting circularly polarized light with different rotation directions at the exit end of the metalens（array）.Compared with the traditional method of generating vortex laser array,all the vortex beams come from the same laser source in this research.And the output of vortex laser with different topological charges can maintain good time coherence and good integration.This research paves a solid step towards the next generation of multidimensional multiplexing technology.更多还原