WO2024051801A1 - 弯曲叉形光栅结构及其弯曲叉形光栅和制备方法 - Google Patents

弯曲叉形光栅结构及其弯曲叉形光栅和制备方法 Download PDF

Info

Publication number
WO2024051801A1
WO2024051801A1 PCT/CN2023/117636 CN2023117636W WO2024051801A1 WO 2024051801 A1 WO2024051801 A1 WO 2024051801A1 CN 2023117636 W CN2023117636 W CN 2023117636W WO 2024051801 A1 WO2024051801 A1 WO 2024051801A1
Authority
WO
WIPO (PCT)
Prior art keywords
grating
curved fork
curved
fork
light
Prior art date
Application number
PCT/CN2023/117636
Other languages
English (en)
French (fr)
Inventor
晋云霞
吴昱博
韩昱行
孔钒宇
曹红超
张益彬
Original Assignee
中国科学院上海光学精密机械研究所
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from CN202211103662.2A external-priority patent/CN116299810A/zh
Priority claimed from CN202311151009.8A external-priority patent/CN117233878A/zh
Application filed by 中国科学院上海光学精密机械研究所 filed Critical 中国科学院上海光学精密机械研究所
Publication of WO2024051801A1 publication Critical patent/WO2024051801A1/zh

Links

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/18—Diffraction gratings

Definitions

  • the invention relates to the field of diffraction gratings, in particular to a curved fork grating structure capable of converting Gaussian light into Bessel Gaussian light, a curved fork grating and a preparation method thereof.
  • a vortex beam is a beam with vortex characteristics.
  • the phase or wavefront of this light is spiral, and the complex amplitude contains a spiral phase term, which can be expressed as where l is the topological charge, is the angular coordinate.
  • Each photon in the vortex beam carries Orbital angular momentum (OAM), and this orbital angular momentum can be transferred to the radiated particles.
  • OFAM Orbital angular momentum
  • Vortex beams have many potential applications, such as in the field of optical communications, manipulation of tiny particles, optical trapping, etc.
  • the ring radius of traditional vortex light increases with the increase of topological charge, so its application in many fields is limited.
  • Ostrovsky et al. first proposed the concept of perfect vortex light. Their ring diameter has nothing to do with the topological charge [Opt Lett 38, 534-536 (2013)], which attracted widespread attention. Perfect vortex light is obtained through the Fourier transform of Bessel Gaussian light.
  • the technical problem to be solved by the present invention is to provide a diffraction grating that can directly convert Gaussian light into Bessel Gaussian light, which has a characteristic curved fork grating structure.
  • a curved fork-shaped grating structure which is characterized in that the curve formed by all points at the same relative position in their respective periods is curved, and there is only a fork-shaped structure distributed between a pair of adjacent curved curves, so that the irradiation is The incident light of the curved fork grating is converted into Bessel Gaussian light;
  • the lateral structure of the curved fork grating is specifically:
  • the distance between any point M and point O on the grating is ⁇
  • the maximum direction of the period density of the curved fork grating is the polar axis Ox
  • the transverse distribution function of the curved fork grating is expressed in the polar coordinate system as:
  • ⁇ is the bending factor of the bending curve
  • l is the topological charge
  • ⁇ is the average period of the grating
  • n is the period number difference between point M and point O
  • x 0 is the relative position of point M in any grating period.
  • the bending factor ⁇ is any positive real number
  • the topological charge value l is any non-zero integer
  • the period number difference n belongs to any integer within the positive and negative N/2 closed interval
  • N is the entire
  • the relative position x 0 is any real number between [0,1).
  • a metal curved fork-shaped grating is characterized in that it adopts the above-mentioned curved fork-shaped grating structure, and the longitudinal structure from bottom to top is a base, a top grating layer and a metal plating layer.
  • a dielectric curved fork-shaped grating is characterized by adopting the above-mentioned curved fork-shaped grating structure, and the longitudinal structure from bottom to top is a base, a multi-layer dielectric film and a top grating layer.
  • a metal dielectric mixed curved fork grating is characterized by adopting the above curved fork grating structure, and the longitudinal structure from bottom to top is a base, a metal dielectric mixed layer and a top grating layer.
  • a method for preparing a curved fork grating which is characterized in that the method includes the following steps:
  • Step 1) Set up a laser, a beam expander, a linear polarizer and a depolarizing beam splitter coaxially; set up a mirror group, a microscopic objective lens with a pinhole, and a first collimating mirror along the reflection light path of the depolarizing beam splitter; Set up the SLM along the transmission light path of the depolarizing beam splitter and connect it to the PC control terminal;
  • Step 2) Start the laser and adjust the angle of the SLM so that the light from the SLM is incident on the depolarizing beam splitter and reflected by it, forming a second beam of reflected light;
  • Step 3) Set a Fourier lens, an aperture, an attenuator, a third reflector and a collimating lens along the second beam of reflected light;
  • Step 4) Control the SLM through the PC control terminal to obtain the Bessel Gaussian light with the target bending factor ⁇ and topological charge value l, and define this light field as the object light field;
  • Step 5 Place a reflector perpendicular to the selection base, adjust the angle of the rotating base, so that the object light field returns to the original path; rotate the rotating base at an angle of ⁇ /2, adjust the position and angle of the reflecting mirror group, so that the two The optical paths completely overlap.
  • the angle between the two optical paths is ⁇
  • the average period of the curved fork grating is:
  • Step 6 Adjust the position and angle of the Fourier lens so that the front focal plane coincides with the SLM screen. Adjust the position of the aperture so that it is located at the focal plane of the lens. Adjust the aperture size so that only the first-order diffracted light passes through the aperture;
  • Step 7) Rotate the polarizer, select the polarization direction with the strongest first-order diffracted light intensity, and adjust the collimating lens position so that the front focal plane of the lens coincides with the plane where the diaphragm is located, and adjust the angle of the collimating lens so that the first-order diffracted light passes vertically through the center of the lens. At this time, the two optical paths interfere and the exposure light field is obtained.
  • Step 8) Prepare metal, dielectric, or metal-dielectric hybrid gratings.
  • the main processes include: coating, exposure in the exposure field described in steps 1-7, development, and etching, but are not limited to permutations and combinations of the above processes.
  • the curved fork grating of the present invention can directly diffract incident Gaussian light into Bessel Gaussian light.
  • the curved fork grating designed by the present invention can effectively utilize the longitudinal structure of various conventional gratings and inherit their performance characteristics. It can achieve a more arbitrary and wider use band than the spiral cone lens, and has a wider range than the SLM. High damage threshold and diffraction efficiency.
  • the present invention defines the stripe distribution of the top grating layer of the designed curved fork grating, which can more effectively guide the design and preparation of curved fork gratings.
  • the present invention is suitable for various optical systems that use conventional straight stripe gratings, such as ultra-strong and ultra-short laser compressors and laser beam combining systems, and can generate Bessel Gaussian light simply and directly.
  • Figure 1 is a schematic diagram of the structure of a curved fork grating of the present invention.
  • the horizontal structure is a curved fork structure.
  • the longitudinal structure can directly adopt the longitudinal structure of a conventional grating.
  • the dotted line is a fork structure distributed between a pair of adjacent curves.
  • Figure 2 is a schematic diagram of grating stripes obtained using the curved fork expression provided by the present invention, as well as the fork structure 1 existing between a pair of adjacent curves.
  • Figure 3 is a cross-sectional view of the longitudinal structure of the metal curved fork grating used in the embodiment of the present invention.
  • the thickness of the top gold layer is 150 nanometers.
  • Figure 4 is a schematic diagram of an optical path using the curved fork grating preparation method provided by the present invention in an embodiment.
  • Figure 5 shows the simulation results of the height distribution of each position on the surface profile of the top grating layer within the range of 2.7 mm in side length around the center of the gold grating obtained by using the curved fork expression provided by the present invention in the embodiment.
  • ⁇ 675.68 nanometers
  • Figure 6 shows the simulation and experimental results of the actual prepared metal curved fork grating using the curved fork distribution formula provided by the present invention in the embodiment.
  • the diffracted light passes through a lens with a focal length of 50 cm, and the intensity distribution changes with the propagation distance.
  • Test results The wavelength of the light source is 413.1 nanometers, the incident angle is 15°45′, and the diffraction angle is 62°.
  • Figure 7 shows the intensity distribution test results of the topological charge value of the diffraction light field of the actually prepared metal curved fork grating using the cylindrical mirror method in the embodiment. There is an inclined dark stripe between the bright spots at the two poles, proving that the diffraction light field The topological charge is 1.
  • This embodiment provides a metal curved fork grating, including: a base 2, a top grating layer 3, and a metal coating 4; the curved fork grating is used to receive p-polarized basic mode Gaussian light, and diffraction order in the +1 order The high-order Bessel Gaussian light with topological charge value l is obtained.
  • Figure 3 is a cross-sectional view of the structure of a metal curved fork grating according to an embodiment of the present invention.
  • the substrate 2 is a quartz substrate
  • the grating layer 3 is a photoresist with a refractive index of 1.6 and has a height of 200 nanometers
  • the metal layer 4 is a metal material gold (Au) with a thickness of 150 nanometers.
  • Design curved fork grating Define the outline of the grating within a complete cycle.
  • the groove depth h 0 is 200 nanometers.
  • the transverse distribution function of the grating structure can be expressed in the polar coordinate system as:
  • the grating period ⁇ is 675.68 nanometers, corresponding to 1480 lines, the total length of the grating stripe direction is 50 millimeters, and there are 37000 periods in total.
  • n is any integer within the closed interval of plus or minus 18500.
  • x 0 0, that is, the curve drawn is a line connecting the starting points of each cycle.
  • the starting point of the cycle is the center position of the grating groove.
  • Figure 4 is a schematic diagram of the preparation device of the metal curved fork grating of the present invention.
  • this Invented device for preparing curved fork gratings including: laser 5, beam expander 6, linear polarizer 7, depolarizing beam splitter 8, reflective pure phase liquid crystal spatial light modulator (SLM) 9, PC control terminal 10 , Fourier lens 11, adjustable aperture diaphragm 12, third reflecting mirror 13, second collimating mirror 14, first reflecting mirror 15, second reflecting mirror 16, microscopic objective lens with pinhole 17, first Collimating mirror 18, grating 19 to be exposed and rotating base 20.
  • SLM spatial light modulator
  • a method for preparing a metal curved fork grating includes the following steps:
  • the wavelength of the laser is 413 nanometers
  • the average period of the curved fork grating is 675.68 nanometers:
  • Step 7) Rotate the polarizer 7, select the polarization direction with the strongest first-order diffracted light intensity, adjust the position of the collimating lens 14, so that the front focal plane of the lens 14 coincides with the plane of the aperture 12, adjust the position of the collimating lens 14 Angle, so that the first-order diffracted light passes through the center of the lens 14 vertically. At this time, the two optical paths interfere and the exposure light field is obtained.
  • Step 8) Prepare a metal grating, the main steps of which include: exposure, development, and metal film plating in the exposure field described in steps 1-7.
  • the metal film material is gold.
  • Figure 5 shows the simulation results of the height distribution of the grating at each position on the surface profile of the top grating layer within a side length of 2.7 mm. Obvious curved Moiré fringes can be observed.
  • Bessel Gaussian light passes through a lens to make it easier to observe its properties.
  • the light field will produce an extremely thin perfect vortex light ring on the focal plane that has nothing to do with the topological charge.
  • Figure 5a(1,2) shows the basic mode Gaussian light passing through a metal curved fork grating with the above parameters.
  • the first-order diffracted light obtained passes through a lens with a focal length of 50 cm.
  • the light field intensity is distributed in front of and on the focal plane. simulation results.
  • Figure 5b(1,2) shows the first-order diffraction obtained by passing the fundamental mode Gaussian light through the actually prepared metal curved fork grating.
  • the wavelength of the laser light source used in the test is 413.1 nanometers, the test incident angle is 15°45′, and the diffraction angle is 62°.
  • Figure 6 shows the measurement of the topological charge of the perfect vortex light shown in Figure 5b(2) using a cylindrical mirror with a focal length of 80 cm.
  • the intensity distribution diagram there is a dark stripe between the bright spots at the two poles. It can be seen that the topological charge of this perfect vortex light is 1, that is, the topological charge of the Bessel Gaussian light generated by the metal curved fork grating in this embodiment is 1. .
  • the curved fork grating structure of the present invention can also be applied to dielectric or metal dielectric hybrid gratings.
  • the preparation method of the dielectric curved fork grating is the same as the preparation method of the metal curved fork grating, except that step 8 is: plating multi-layer dielectric film, exposure, development, and etching in the exposure field described in steps 1-7.
  • the preparation method of the metal dielectric mixed curved fork grating is the same as the preparation method of the metal curved fork grating, except that in step 8, the preparation process is: plating the metal dielectric mixed film, exposure, development, and etching in the exposure field described in steps 1-7. .

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Diffracting Gratings Or Hologram Optical Elements (AREA)

Abstract

一种弯曲叉形光栅结构及其弯曲叉形光栅和制备方法。弯曲叉形光栅中，所有处于各自周期相同相对位置的点所构成的曲线呈弯曲叉形分布，以使照射在弯曲叉形光栅的入射光转变为贝塞尔高斯光。这种弯曲叉形可通过各种光栅实现，如金属光栅、介质光栅、或金属介质混合光栅，同时不影响它们的本征特性，如衍射效率、使用波段、衍射角度、偏振特性等，仅使衍射光场携带高阶贝塞尔相位。这种提供的弯曲叉形光栅相比于现有技术中获得贝塞尔高斯光的方法，光路更为简单，适用于宽波段。

Description

弯曲叉形光栅结构及其弯曲叉形光栅和制备方法 技术领域
本发明涉及衍射光栅领域，特别是一种能将高斯光转变为贝塞尔高斯光的弯曲叉形光栅结构，及其弯曲叉形光栅和制备方法。
背景技术
涡旋光束是具有涡旋特性的光束，这种光的相位或波前呈螺旋形，复振幅含有螺旋相位项，可以表示为其中l是拓扑荷，是角向坐标。涡旋光束中的每一个光子都携带的轨道角动量(OAM)，并且这种轨道角动量可以传递到被辐射的微粒上。涡旋光束在许多潜在的应用价值，比如用在光通信领域、操纵微小粒子、光学诱捕等方面。但是传统的涡旋光的环半径会随着拓扑荷值的增大而增大，因此在很多领域中应用受到了限制。2013年，Ostrovsky等人首次提出完美涡旋光这一概念，它们的环径与拓扑荷值无关【Opt Lett 38,534-536(2013)】，受到了广泛的关注。完美涡旋光是通过贝塞尔高斯光的傅里叶变换得到的。
目前生成贝塞尔高斯光场最普遍方式是用液晶空间光调制器(SLM)加载计算全息图的方式，但是此方法成本高，衍射效率低，其液晶结构使损伤阈值难以提高。也有通过将螺旋相位板和锥透镜级联的方式，获得高阶贝塞尔高斯光【Opt Lett 41,1348-1351(2016)】，进而产生完美涡旋光，但光路非常复杂，光学中心也难以对准，并且只能应用于单一波长。
发明内容
本发明要解决的技术问题是提供一种能将高斯光直接转换为贝塞尔高斯光的衍射光栅，其具有特征的弯曲叉形光栅结构。
本发明的解决方案如下：
一种弯曲叉形光栅结构，其特点在于，所有处于各自周期相同相对位置的点所构成的曲线呈弯曲分布，且仅有一对相邻的弯曲曲线之间分布有叉形结构，以使照射在所述弯曲叉形光栅的入射光转变为贝塞尔高斯光；
所述的弯曲叉形光栅横向结构具体为：
以所述叉形结构的分叉点为极点O，光栅上的任意一点M与O点间的距离为ρ， 弯曲叉形光栅周期密度极大方向为极轴Ox，则弯曲叉形光栅横向分布函数在极坐标系中表示为：
其中，γ为弯曲曲线的弯曲因子，为极角，l为拓扑荷值，Λ为光栅的平均周期，n为M点与O点之间的周期数差，x0为M点在任一光栅周期内的相对位置。
所述的弯曲因子γ为任一正实数，所述的拓扑荷值l为任一非零整数，所述的周期数差n属于正负N/2闭区间内的任一整数，N为整个光栅口径内的总周期数，所述的相对位置x0取[0,1)之间的任意实数。
一种金属的弯曲叉形光栅，其特点在于，采用上述弯曲叉形光栅结构，且纵向结构由下至上依次为基底、顶部光栅层和金属镀层。
一种介质的弯曲叉形光栅，其特点在于，采用上述弯曲叉形光栅结构，且纵向结构由下至上依次为基底、多层介质膜和顶部光栅层。
一种金属介质混合弯曲叉形光栅，其特点在于，采用上述弯曲叉形光栅结构，且纵向结构由下至上依次为基底、金属介质混合层和顶部光栅层。
一种弯曲叉形光栅的制备方法，其特点在于，该方法包括如下步骤：
步骤1)同轴设置激光器、扩束器、线偏振片和消偏振分束器；沿消偏振分束器的反射光路设置反射镜组、带针孔的显微物镜、第一准直镜；沿消偏振分束器的透射光路设置SLM，与PC控制端相连；
步骤2)启动激光器，调整SLM的角度，使SLM的光入射至消偏振分束器并被其反射，形成第二束反射光；
步骤3)沿所述的第二束反射光设置傅里叶透镜、光阑、衰减片、第三反射镜和准直透镜；
步骤4)通过PC控制端控制SLM，获得具有目标弯曲因子γ和拓扑荷值l的贝塞尔高斯光，将此光场定义为物光场；
步骤5)将一反射镜垂直于选择基座放置，调节旋转基座角度，使物光场以原路返回；转动旋转基座φ/2角度，调节反射镜组的位置与角度，使两条光路完全重合，此时两条光路夹角为φ，弯曲叉形光栅的平均周期为：
步骤6)调节傅里叶透镜的位置与角度，使前焦面与SLM屏幕重合，调节光阑的位置，使其位于透镜的焦平面，调节孔径大小，仅使1级衍射光经过光阑；
步骤7)旋转偏振片，选择1级衍射光强相对最强的偏振方向，调节准直透镜 的位置，使透镜的前焦面与光阑所在平面重合，调节准直透镜的角度，使1级衍射光垂直经过透镜中心。此时两光路发生干涉，获得曝光光场。
步骤8)制备金属、介质、或金属介质混合光栅，其主要工序包括：镀膜、在步骤1-7所述曝光场中曝光、显影、和刻蚀，但不限于对以上工序进行排列组合。
本发明的技术效果如下：
1)与常规直条纹光栅相比，本发明的弯曲叉形光栅可以直接将入射的高斯光衍射转变为贝塞尔高斯光。
2)本发明设计的弯曲叉形光栅可有效利用各类常规光栅的纵向结构并继承其性能特性，可实现相比于螺旋锥透镜具有更任意、更宽的使用波段，相比于SLM具有更高的损伤阈值和衍射效率。
3)本发明对所设计的弯曲叉形光栅的顶部光栅层条纹分布进行了定义，能更有效的指导弯曲叉形光栅的设计和制备。
4)本发明适配应用常规直条纹光栅的各类光学系统，如超强超短激光压缩器、激光合束系统，可简单直接地生成贝塞尔高斯光。
附图说明
图1为本发明弯曲叉形光栅结构示意图，横向结构为弯曲叉形结构，纵向结构可直接采用常规光栅的纵向结构，虚线为一对相邻弯曲曲线之间分布的叉形结构。
图2为采用本发明提供的弯曲叉形表达式得到的光栅条纹示意图，以及一对相邻弯曲曲线之间存在的叉形结构1。
图3为本发明实施例中采用的金属弯曲叉形光栅纵向结构剖面图，顶层金层厚度150纳米。
图4为实施例中采用本发明提供的弯曲叉形光栅制备方法的光路示意图。
图5为实施例中采用本发明提供的弯曲叉形表达式得到的金光栅，在中心周围边长2.7毫米的范围内，顶部光栅层表面轮廓上各位置的高度分布的仿真结果。Λ＝675.68纳米，l＝1，γ＝9.5×10-4。
图6为实施例中采用本发明提供的弯曲叉形分布公式，实际制备出的金属弯曲叉形光栅，衍射光经过焦距为50厘米的透镜，强度分布随传播距离变化的仿真与实验结果，测试光源的波长为413.1纳米，入射角度为15°45′，衍射角度为62°。
图7为实施例中采用柱面镜法，测量实际制备出的金属弯曲叉形光栅衍射光场拓扑荷值的强度分布测试结果，两极亮点之间存在一条倾斜暗条纹，证明衍射光场 拓扑荷值为1。
图中：1、叉形结构；2、基底；3、顶部光栅层；4、金属镀层；5、激光器；6、扩束器；7、线偏振片；8、消偏振分束器；9、反射式纯相位液晶空间光调制器(SLM)；10、PC控制端；11、傅里叶透镜；12、可调孔径光阑；13、第三反射镜；14、第二准直镜；15、第一反射镜；16、第二反射镜；17、带针孔的显微物镜；18、第一准直镜；19、待曝光的光栅样品；20、旋转基座。
具体实施方式
为了更好的理解上述技术方案，下面将结合说明书附图以及具体实施方式对上述技术方案进行更详细的说明。
本实施例提供一种金属弯曲叉形光栅，包括：基底2、顶部光栅层3、金属镀层4；所述弯曲叉形光栅用于接收p偏振的基模高斯光，并在+1级衍射级上得到拓扑荷值为l的高阶贝塞尔高斯光。
图3为本发明实施例金属弯曲叉形光栅结构剖面图。其中基底2采用石英基底，光栅层3采用折射率1.6的光刻胶，高度为200纳米，金属层4采用金属材料金(Au)，厚度为150纳米。
设计弯曲叉形光栅。对光栅的一个完整周期内的外型轮廓进行定义，高度h与周期内相对位置x0的关系取为三角函数关系：
h(x0)＝[sin(2πx0-π/2)+1]×h0
其中槽深h0取200纳米。
以叉形结构中心为极点O，光栅上的任意一点M与O点间的距离为ρ。以弯曲叉形光栅周期密度极大方向为极轴Ox，光栅结构横向分布函数可在极坐标系中表示为：
本实施例中，光栅周期Λ为675.68纳米，对应线度1480线，光栅条纹方向总长度50毫米，共有37000个周期，n取遍正负18500闭区间内的任一整数。x0＝0，即所作的曲线为每个周期起始点连线，在本实施例中，周期的起始点为光栅凹槽中心位置。拓扑荷值l＝1，即光栅中心位置处的叉数为1，弯曲参数γ＝9.5×10-4。
请参阅7，图4是本发明金属弯曲叉形光栅的制备装置示意图。由图可见，本 发明弯曲叉形面光栅的制备装置，包括：激光器5、扩束器6、线偏振片7、消偏振分束器8、反射式纯相位液晶空间光调制器(SLM)9、PC控制端10、傅里叶透镜11、可调孔径光阑12、第三反射镜13、第二准直镜14、第一反射镜15、第二反射镜16、带针孔的显微物镜17、第一准直镜18、待曝光的光栅19和旋转基座20。
制备金属弯曲叉形面光栅的方法，包括如下步骤：
1)同轴设置激光器5、扩束器6、线偏振片7和消偏振分束器8；沿消偏振分束器8的反射光路设置反射镜组15-16、带针孔的显微物镜17、第一准直镜18；沿消偏振分束器8的透射光路设置SLM 9，与PC控制端10相连；
2)启动激光器5，使SLM的反射光入射至消偏振分束器8并被其反射，形成第二束反射光，实施例中激光器波长为413纳米；
3)沿所述的第二束反射光设置傅里叶透镜11、可调孔径光阑12、第三反射镜13和第二准直镜14；
4)通过PC控制端10控制SLM 9，获得具有目标弯曲因子γ＝9.5×10-4和拓扑荷值l＝1的贝塞尔高斯光，将此光场定义为物光场；
5)将一反射镜垂直于选择基座20放置，调节旋转基座的角度，使物光路以原路返回；转动旋转基座23°7′17″，调节反射镜组15-16位置与角度，使两条光路重合，此时弯曲叉形光栅的平均周期为675.68纳米：
6)调节傅里叶透镜11的位置与角度，使前焦面与SLM屏幕重合，调节光阑12的位置，使其位于透镜11的焦平面，调节孔径大小，仅使1级衍射光经过光阑；
步骤7)旋转偏振片7，选择1级衍射光强相对最强的偏振方向，调节准直透镜14的位置，使透镜14的前焦面与光阑12所在平面重合，调节准直透镜14的角度，使1级衍射光垂直经过透镜14中心。此时两光路发生干涉，得到曝光光场。
步骤8)制备金属光栅，其主要工序包括：在步骤1-7所述曝光场中曝光、显影、和镀金属膜，实施例中金属膜材料为金。
图5为光栅在边长为2.7毫米的范围内，顶部光栅层表面轮廓上各位置的高度分布的仿真结果，可以观察到明显的弯曲摩尔条纹。
在检测时，贝塞尔高斯光经过透镜更便于观察其性质，光场会在焦平面上产生一个极细的、与拓扑荷值无关的完美涡旋光圆环，而在远离焦平面的位置处呈现同心环型的光强分布。图5a(1,2)为基模高斯光经过上述参数所得的金属弯曲叉形光栅，获得的1级衍射光，经过焦距为50厘米的透镜，光场强度分布在焦平面前和焦平面上的仿真结果。
图5b(1,2)为基模高斯光经过实际制备出的金属弯曲叉形光栅，获得的1级衍射 光，经过焦距为50厘米的透镜，光场强度分布在焦平面前和焦平面上的实验结果。测试使用的激光光源波长为413.1纳米，测试入射角度为15°45′，衍射角度为62°。
图6为使用焦距为80厘米的柱面镜，测量图5b(2)所示的完美涡旋光的拓扑荷值。在强度分布图中，两极亮点之间存在一条暗条纹，可知此完美涡旋光的拓扑荷值为1，即本实施例中金属弯曲叉形光栅所产生的贝塞尔高斯光拓扑荷值为1。
本发明中弯曲叉形光栅结构除适用于金属弯曲叉形光栅外，还可以适用于介质或金属介质混合光栅。
介质弯曲叉形光栅的制备除步骤8，制备工序为：镀多层介质膜、在步骤1-7所述曝光场中曝光、显影、刻蚀外，与金属弯曲叉形光栅制备方法相同。
金属介质混合弯曲叉形光栅的制备除步骤8，制备工序为：镀金属介质混合膜、在步骤1-7所述曝光场中曝光、显影、刻蚀外，与金属弯曲叉形光栅制备方法相同。
以上所述仅是本发明的优选实施方式，应当指出，对于本技术领域的普通技术人员，在不脱离本发明方法的前提下，还可以做出若干改进和补充，这些改进和补充也应视为本发明的保护范围。

Claims (7)

  1. 一种弯曲叉形光栅结构，其特点在于，所有处于各自周期相同相对位置的点所构成的曲线呈弯曲分布，且仅有一对相邻的弯曲曲线之间分布有叉形结构，以使照射在所述弯曲叉形光栅的入射光转变为贝塞尔高斯光；
    以所述叉形结构的分叉点为极点O，光栅上的任意一点M与O点间的距离为ρ，弯曲叉形光栅周期密度极大方向为极轴Ox，则弯曲叉形光栅横向分布函数在极坐标系中表示为：
    其中，γ为弯曲曲线的弯曲因子，为极角，l为拓扑荷值，Λ为光栅的平均周期，n为M点与O点之间的周期数差，x0为M点在任一光栅周期内的相对位置。
  2. 如权利要求1所述的弯曲叉形光栅结构，其特点在于：所述的弯曲因子γ为任一正实数，所述的拓扑荷值l为任一非零整数，所述的周期数差n属于正负N/2闭区间内的任一整数，N为整个光栅口径内的总周期数，所述的相对位置x0取[0,1)之间的任意实数。
  3. 如权利要求1所述的弯曲叉形光栅结构，其特点在于：所述的弯曲叉形光栅为金属、介质、或金属介质混合光栅。
  4. 一种金属的弯曲叉形光栅，其特点在于，采用权利要求1-3任一所述的弯曲叉形光栅结构，且纵向结构由下至上依次为基底、顶部光栅层和金属镀层。
  5. 一种介质的弯曲叉形光栅，其特点在于，采用权利要求1-3任一所述的弯曲叉形光栅结构，且纵向结构由下至上依次为基底、多层介质膜和顶部光栅层。
  6. 一种金属介质混合弯曲叉形光栅，其特点在于，采用权利要求1-3任一所述的弯曲叉形光栅结构，且纵向结构由下至上依次为基底、金属介质混合层和顶部光栅层。
  7. 一种权利要求4-6任一所述的弯曲叉形光栅的制备方法，其特点在于，该方法包括如下步骤：
    步骤1)同轴设置激光器(5)、扩束器(6)、线偏振片(7)和消偏振分束器(8)；沿消偏振分束器(8)的反射光路设置反射镜组(15-16)、带针孔的显微物镜(17)、第一准直镜(18)；沿消偏振分束器(8)的透射光路设置SLM(9)，与PC控制端(10)相连；
    步骤2)启动激光器(5)，使SLM的反射光入射至消偏振分束器8并被其反射，形成第二束反射光；
    步骤3)沿所述的第二束反射光设置傅里叶透镜(11)、可调孔径光阑(12)、第三 反射镜(13)和第二准直镜(14)；
    步骤4)通过PC控制端(10)控制SLM(9)，获得具有目标弯曲因子γ和拓扑荷值l的贝塞尔高斯光，将此光场定义为物光场；
    步骤5)将一反射镜垂直于选择基座(20)放置，调节旋转基座的角度，使物光路以原路返回；转动旋转基座φ/2角度，调节反射镜组(15-16)位置与角度，使两条光路重合，此时两条光路夹角为φ，弯曲叉形光栅的平均周期为：
    步骤6)调节傅里叶透镜(11)的位置与角度，使前焦面与SLM屏幕重合，调节光阑(12)的位置，使其位于透镜(11)的焦平面，调节孔径大小，仅使1级衍射光经过光阑；
    步骤7)旋转偏振片(7)，选择1级衍射光强相对最强的偏振方向，调节准直透镜(14)的位置，使透镜(14)的前焦面与光阑(12)所在平面重合，调节准直透镜(14)的角度，使1级衍射光垂直经过透镜(14)中心。此时两光路发生干涉，得到曝光光场。
    步骤8)制备金属、介质、或金属介质混合光栅，其主要工序包括：镀膜、在步骤1-7所述曝光场中曝光、显影、和刻蚀，但不限于对以上工序进行排列组合。
PCT/CN2023/117636 2022-09-09 2023-09-08 弯曲叉形光栅结构及其弯曲叉形光栅和制备方法 WO2024051801A1 (zh)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
CN202211103662.2 2022-09-09
CN202211103662.2A CN116299810A (zh) 2022-09-09 2022-09-09 一种反射式弯曲叉形面光栅的制备装置和方法
CN202311151009.8 2023-09-07
CN202311151009.8A CN117233878A (zh) 2023-09-07 2023-09-07 一种弯曲叉形光栅结构及其弯曲叉形光栅

Publications (1)

Publication Number Publication Date
WO2024051801A1 true WO2024051801A1 (zh) 2024-03-14

Family

ID=90192079

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2023/117636 WO2024051801A1 (zh) 2022-09-09 2023-09-08 弯曲叉形光栅结构及其弯曲叉形光栅和制备方法

Country Status (1)

Country Link
WO (1) WO2024051801A1 (zh)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2021043295A (ja) * 2019-09-10 2021-03-18 林テレンプ株式会社 偏光回折素子と、これを用いたベクトルビームのモード検出システム
CN112782861A (zh) * 2021-01-14 2021-05-11 合肥工业大学 基于复合相位全息图的自恢复oam模式通信系统
US20210376552A1 (en) * 2018-09-26 2021-12-02 Imperial College Innovations Limited Methods and apparatus for laser mode transformation
CN114689170A (zh) * 2022-03-28 2022-07-01 中国科学院上海光学精密机械研究所 大拓扑荷值单模完美涡旋光的测量装置和方法
CN116299810A (zh) * 2022-09-09 2023-06-23 中国科学院上海光学精密机械研究所 一种反射式弯曲叉形面光栅的制备装置和方法

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20210376552A1 (en) * 2018-09-26 2021-12-02 Imperial College Innovations Limited Methods and apparatus for laser mode transformation
JP2021043295A (ja) * 2019-09-10 2021-03-18 林テレンプ株式会社 偏光回折素子と、これを用いたベクトルビームのモード検出システム
CN112782861A (zh) * 2021-01-14 2021-05-11 合肥工业大学 基于复合相位全息图的自恢复oam模式通信系统
CN114689170A (zh) * 2022-03-28 2022-07-01 中国科学院上海光学精密机械研究所 大拓扑荷值单模完美涡旋光的测量装置和方法
CN116299810A (zh) * 2022-09-09 2023-06-23 中国科学院上海光学精密机械研究所 一种反射式弯曲叉形面光栅的制备装置和方法

Similar Documents

Publication Publication Date Title
US10677992B2 (en) Device for forming at least one focused beam in the near zone, from incident electromagnetic waves
US11396474B2 (en) Method for manufacturing a device for forming at least one focused beam in a near zone
WO2017181530A1 (zh) 宽带电磁波相位调控的方法和超表面亚波长结构
WO2021093259A1 (zh) 一种任意奇点光束阶数检测装置及方法
Zhang et al. Ultrahigh-capacity dynamic holographic displays via anisotropic nanoholes
Zhang et al. Polarization-independent broadband meta-holograms via polarization-dependent nanoholes
KR102262913B1 (ko) 편광과 포커싱 제어가 가능한 반파장판 메타표면, 메타렌즈 및 이들의 제조방법
CN106094217B (zh) 自聚焦光束发生器及其设计方法
CN104111590B (zh) 基于复合涡旋双瓣聚焦光斑的激光直写装置
TWI805647B (zh) 光產生裝置、具備光產生裝置的曝光裝置、曝光系統、光產生方法、及曝光光阻的製造方法
Fu et al. Measuring phase and polarization singularities of light using spin-multiplexing metasurfaces
CN113064284A (zh) 一种基于高阶交叉相位的多边形完美涡旋光制备与操控方法
CN112964375A (zh) 一种基于交叉相位的圆艾里涡旋光检测与操控方法
Kotlyar et al. A dual-functionality metalens to shape a circularly polarized optical vortex or a second-order cylindrical vector beam
Sedukhin et al. Efficient tight focusing of laser beams optimally matched to their thin-film linear-to-radial polarization conversion: Method, implementation, and field near focus
WO2024050973A1 (zh) 一种反射式弯曲叉形面光栅的制备装置和方法
CN110320672B (zh) 一种太赫兹涡旋光产生器、制备方法及产生系统
Wang et al. Broadband generation of abruptly autofocusing terahertz ring-Airy beams with all-silicon metasurface
CN111948806B (zh) 超构表面彩虹系统的设计与实现方法
CN114815278A (zh) 一种具有突然自聚焦效应且携带一个涡旋的一阶圆艾里导数光束的产生及其测量方法
WO2024051801A1 (zh) 弯曲叉形光栅结构及其弯曲叉形光栅和制备方法
WO2023216472A1 (zh) 通过引入附加相位调控变焦超透镜焦距范围的方法
CN109254336A (zh) 非完全对称微介质轴锥镜相位器件
Shi et al. Controllable Self‐Focusing Circular Vortex Pearcey Gaussian Beam with Low Spatial Coherence
KR102446874B1 (ko) 메타표면 기반 엑시콘 디바이스, 이를 포함하는 광학 장치 및 이의 제조 방법

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 23862495

Country of ref document: EP

Kind code of ref document: A1