液晶几何相位技术实现光场空间结构全维度调控  

Full control of structured light with liquid-crystal geometric phase

作　　者：李春宇 于丙石 赵波[1] Carmelo Rosales-Guzman 白振旭 朱智涵[1] Li Chunyu;Yu Bingshi;Zhao Bo;Carmelo Rosales-Guzman;Bai Zhenxu;Zhu Zhihan(Wang Da-Heng Collaborative Innovation Center,Heilongjiang Province Key Laboratory of Quantum Control,Harbin University of Science and Technology,Harbin 150080,China;Center for Advanced Laser Technology,Hebei University of Technology,Tianjin 300401,China)

机构地区：[1]哈尔滨理工大学黑龙江省量子调控重点实验室大珩协同创新中心,黑龙江哈尔滨150080 [2]河北工业大学先进激光技术研究中心,天津300401

出　　处：《红外与激光工程》2023年第8期298-300,共3页Infrared and Laser Engineering

基　　金：国家自然科学基金项目(62075050,11934013,61975047)。

摘　　要：几何相位平面光学元件由于高效、紧凑及易集成等优点已被广泛用于光场空间结构调控。但以q-plate为代表的此类元件只提供自旋相关的波前控制能力,振幅调控能力的缺失导致无法利用光场的全部空间维度,严重阻碍了相关领域研究的进一步深化。笔者团队在国家自然科学基金等项目资助下,以液晶人工微结构中的几何相位为物理基础设计并论证一系列新型几何相位元件,解锁了平面光学技术对近轴结构光场的全维度调控能力,为高维经典及量子信息等需要依托光场调控技术的实验研究提供了重要工具。Significance Flat optics elements based on geometric phase,owing to their low cost,integrability,and versatility,have been widely used in shaping of light's spatial structure.Notably,current SOC(spin-orbit coupling)devices,such as the best-known q-plates,provide only spatial phase modulation with SoP(state of polarization)-switchable behavior.The absence of amplitude control prevents research scholars from accessing light's full spatial degrees of freedom,thus limiting their application in corresponding studies.This team demonstrates a series of novel flat optics elements with liquid-crystal geometric phase,which unlocks the fullfield control of paraxial structured light,providing a powerful toolbox for relevant experimental studies and especially for high-dimensional classical/quantum information.ProgressSTo control a paraxial SOC state in all its spatial degrees of freedom,spin-dependent complex amplitude modulation provides an essential alternative.But up to now,it has remained elusive with flat optics.This paper fills this gap by putting forward a new type of geometric phase element termed structured geometricphase grating(SGPG),featuring a spatially-varying grating cycle,depth and orientation(Fig.1).In addition,the joint team also demonstrated the vector wavefront control technology based on the geometric phase of liquid crystals,and developed a series of liquid crystal geometric phase elements(e.g.,mode convertor(Fig.2(a))and high-order spatial mode generator(Fig.2(b))with the full dimensional control ability.Conclusions and Prospects Such a crucial advance,compared with the present geometric phase elements,unlocks the control of paraxial structured light in all spatial dimensions,and paves the way for arbitrary SOC conversion via flat optics.This capability makes it a key extra-/intracavity component to build a structured laser that has greater tunability in beam structure,compared with reported systems based on q-plate and metasurface.For quantum optics,the proposed reciprocal SOC interface allows to impl

关 键 词：几何位相 液晶 平面光学 光场调控 

分 类 号：O439[机械工程—光学工程]