Elliptic skewness controllable vector vortex beam design method based on metasurface and related equipment

Abstract

The invention discloses an elliptic polarization controllable vector vortex light beam design method based on a metasurface and related equipment, and the method comprises the steps: obtaining a target light field of a vector vortex light beam, and decomposing the target light field into a first light field and a second light field which have a preset polarization state; the parameters of the first light field and the second light field comprise multi-degree-of-freedom parameters; determining a first target phase of each position according to the first light field; determining a second target phase of each position according to the second light field; determining a first rotation angle of each position of the metamaterial surface according to the first target phase of each position to obtain a first phase diagram; determining a second rotation angle of each position of the metasurface according to the second target phase of each position to obtain a second phase diagram; and attenuating and combining the first phase diagram and the second phase diagram according to the target ellipsometry to obtain the metasurface through which the vector vortex beam passes. According to the embodiment of the invention, multiple degrees of freedom and ellipsometry can be regulated and controlled at the same time. The method can be widely applied to the technical field of optical information.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical information technology, in particular to a design method of an ellipsoidal controllable vector vortex beam based on a superstructure surface and related equipment. BACKGROUND

[0002] A perfect vortex beam is a special beam whose light intensity distribution does not change with the change of the topological charge of the beam. Compared with ordinary vortex beams, it can greatly improve the application efficiency and scenarios in particle manipulation, fiber transmission, etc. In previous studies, the fundamental mode Gaussian beam is usually changed into a Laguerre Gaussian beam after passing through a spiral phase plate, and then into a Bessel Gaussian beam after passing through a conical mirror, and finally into a perfect vortex beam after passing through a lens. However, less attention is paid to adjusting the ellipsoidal controllability of perfect vector vortex beams. SUMMARY

[0003] The main purpose of the embodiments of the present application is to provide a design method of an ellipsoidal controllable vector vortex beam based on a superstructure surface and related equipment, which can simultaneously control multiple degrees of freedom and ellipsoidal controllability.

[0004] To achieve the above-mentioned purpose, one aspect of the embodiments of the present application provides a design method of an ellipsoidal controllable vector vortex beam based on a superstructure surface, which comprises the following steps: Obtaining a target light field of a vector vortex beam, decomposing the target light field into a first light field and a second light field with a preset polarization state; the parameters of the first light field and the second light field both include multiple degrees of freedom parameters; According to the first light field, determining the first target phase of each position to obtain a first phase map; according to the second light field, determining the second target phase of each position to obtain a second phase map; According to the first target phase of each position of the first phase map, determining the first rotation angle of each position of the superstructure surface to obtain a first phase map; according to the second target phase of each position of the second phase map, determining the second rotation angle of each position of the superstructure surface to obtain a second phase map; Obtaining a target ellipsoidal controllability, attenuating and merging the first phase map and the second phase map according to the target ellipsoidal controllability, to obtain a superstructure surface through which a vector vortex beam passes.

[0005] In some embodiments, the decomposition of the target light field into a first light field and a second light field with a preset polarization state comprises: According to the preset polarization state, determining a first light field containing a preset target parameter; the target parameter includes a preset beam amplitude, a starting phase, a radius, a topological charge and an imaging position; determining the second light field according to the target light field and the first light field; a topological charge of the second light field is obtained by preset adjustment of a topological charge of the first light field.

[0006] In some embodiments, the determining the first target phase of each position according to the first light field to obtain a first phase map, and the determining the second target phase of each position according to the second light field to obtain a second phase map, comprises: performing Fourier transform on the first light field, and extracting the first target phase according to the first light field after Fourier transform to obtain the first phase map; performing Fourier transform on the second light field, and extracting the second target phase according to the second light field after Fourier transform to obtain the second phase map.

[0007] In some embodiments, the determining the first rotation angle of each position of the metasurface according to the first target phase of each position of the first phase map, and the determining the second rotation angle of each position of the metasurface according to the second target phase of each position of the second phase map, comprises: determining a first angle size according to the first target phase of each position of the first phase map and a preset angle calculation formula, and determining the first rotation angle of each position of the metasurface according to the first angle size and a first preset rotation direction to obtain the first phase map; determining a second angle size according to the second target phase of each position of the second phase map and the preset angle calculation formula, and determining the second rotation angle of each position of the metasurface according to the second angle size and a second preset rotation direction to obtain the second phase map.

[0008] In some embodiments, the attenuating and merging the first phase map and the second phase map according to the target ellipticity to obtain the metasurface through which the vector vortex beam passes, comprises: calculating a proportion of the first phase map according to the target ellipticity and a preset proportion calculation formula, and randomly attenuating the first phase map according to the proportion; Barbier attenuating the second phase map according to the position of the first phase map randomly attenuated; merging the attenuated first phase map and the attenuated second phase map to obtain the metasurface through which the vector vortex beam passes.

[0009] In some embodiments, the preset proportion calculation formula is determined by the following method, comprising: calculating a difference expression and a sum expression of the first preset rotation direction circularly polarized light and the second preset rotation direction circularly polarized light according to the proportion; The preset proportion calculation formula is determined according to the difference expression, the sum value expression and the target ellipticity.

[0010] To achieve the above object, another aspect of the embodiment of the present application provides a design device of an ellipticity-controllable vector vortex beam based on a super-structured surface, which comprises: The decomposition module is configured to obtain a target light field of the vector vortex beam, and decompose the target light field into a first light field and a second light field with preset polarization states; the parameters of the first light field and the second light field both include multi-degree-of-freedom parameters. The image map determination module is configured to determine a first target phase of each position according to the first light field, and obtain a first image map; and determine a second target phase of each position according to the second light field, and obtain a second image map. The phase map determination module is configured to determine a first rotation angle of each position of the super-structured surface according to the first target phase of each position of the first image map, and obtain a first phase map; and determine a second rotation angle of each position of the super-structured surface according to the second target phase of each position of the second image map, and obtain a second phase map. The super-structured surface determination module is configured to obtain a target ellipticity, and perform attenuation and combination on the first phase map and the second phase map according to the target ellipticity, and obtain a super-structured surface through which the vector vortex beam passes.

[0011] To achieve the above object, another aspect of the embodiment of the present application provides an electronic device, which comprises a memory and a processor, the memory stores a computer program, and the processor implements the above method when executing the computer program.

[0012] To achieve the above object, another aspect of the embodiment of the present application provides a computer readable storage medium, which stores a computer program, and the computer program implements the above method when executed by a processor.

[0013] To achieve the above object, another aspect of the embodiment of the present application provides a computer program product, which comprises a computer program, and the computer program implements the above method when executed by a processor.

[0014] The embodiments of the present application at least have the following beneficial effects: the present application provides a method and device for designing an ellipsoidal degree controllable vector vortex beam based on a super-structured surface, an electronic device, a storage medium, and a program product, which decomposes a target light field into a first light field and a second light field with a preset polarization state, and the parameters of the first light field and the second light field both include multi-degree-of-freedom parameters, thereby realizing the regulation and control of the multi-degree-of-freedom; the first target phase of each position is determined according to the first light field to obtain a first phase map, and the second target phase of each position is determined according to the second light field to obtain a second phase map, the first rotation angle of each position of the super-structured surface is determined according to the first target phase of each position of the first phase map to obtain a first phase map, and the second rotation angle of each position of the super-structured surface is determined according to the second target phase of each position of the second phase map to obtain a second phase map, the target phase in the phase map is converted into the rotation angle in the phase map, the first phase map and the second phase map are attenuated and combined according to the target ellipsoidal degree to obtain a super-structured surface through which a vector vortex beam passes, and the super-structured surface is determined according to the target ellipsoidal degree and the two phase maps, thereby realizing the regulation and control of the ellipsoidal degree. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a flowchart of a method for designing an ellipsoidal degree controllable vector vortex beam based on a super-structured surface provided by the embodiments of the present application; Figure 2 is a flowchart of determining a first light field and a second light field provided by the embodiments of the present application; Figure 3 is a flowchart of determining a first phase map and a second phase map provided by the embodiments of the present application; Figure 4 is a flowchart of determining a first phase map and a second phase map provided by the embodiments of the present application; Figure 5 is a flowchart of determining a super-structured surface provided by the embodiments of the present application; Figure 6 is a flowchart of determining a preset proportion calculation formula provided by the embodiments of the present application; Figure 7 is an embodiment diagram of determining a super-structured surface provided by the embodiments of the present application; Figure 8 is a conceptual diagram of experimental results of a perfect vector vortex beam changing with transmission distance provided by the embodiments of the present application; Figure 9 is a simulation result diagram of a perfect vector vortex beam provided by the embodiments of the present application; Figure 10 is a structural schematic diagram of a device for designing an ellipsoidal degree controllable vector vortex beam based on a super-structured surface provided by the embodiments of the present application; Figure 11Fig. 1 is a schematic diagram of a hardware structure of an electronic device provided by an embodiment of the present application. DETAILED DESCRIPTION

[0016] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not intended to limit the present application. When the following description refers to the accompanying drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all the implementations consistent with embodiments of the present application. They are only examples of devices and methods consistent with some aspects of the embodiments of the present application as detailed in the appended claims.

[0017] It can be understood that the terms "first", "second", and the like used in the present application can be used herein to describe various concepts, but unless specifically stated, these concepts are not limited by these terms. These terms are only used to distinguish one concept from another. For example, without departing from the scope of the embodiments of the present application, the first information can also be referred to as the second information, and similarly, the second information can also be referred to as the first information. Depending on the context, the word "if" as used herein can be interpreted as "when" or "when" or "in response to determining".

[0018] The terms "at least one", "multiple", "each", "any" and the like used in the present application include one, two or more than two, multiple includes two or more than two, each refers to each of the corresponding multiple, and any refers to any one of the multiple.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as understood by those skilled in the art to which the present application belongs. The terms used herein are only for the purpose of describing the embodiments of the present application and are not intended to limit the present application.

[0020] Before the embodiments of the present application are described in detail, first, some nouns and terms involved in the embodiments of the present application are described, and the nouns and terms involved in the embodiments of the present application are applicable to the following explanations.

[0021] Topological charge is a description of the helical phase order of the light beam, and the orbital angular momentum is a description of the phase order of a single photon in the vortex light beam, which can essentially reflect the helical phase order of the vortex light beam.

[0022] P-B phase, i.e. Pancharatnam-Berry phase refers to a kind of super surface phase control mode, which has strong polarization selectivity, and the circular polarization chirality usually responds to the rotation angle of the nano unit in the opposite direction.

[0023] Two cross-circularly polarized perfect vortex beams can be superimposed to generate a perfect vector vortex beam. In general, a metasurface can achieve the phase accumulation of multiple optical devices, thereby achieving similar functions. Most of the perfect vector vortex beams generated in the works are generated by superimposing two cross-circularly polarized perfect vortex beams, so generating two cross-circularly polarized perfect vortex beams and coaxially superimposing them is the key to perfect vector vortex beams. Due to the polarization selectivity of the P-B phase of the metasurface, the generated light field often has circular polarization characteristics, and the ultra-thin and easy-to-integrate characteristics of the metasurface make it more advantageous to generate perfect vector vortex beams, but it is difficult to obtain perfect vector vortex beams with controllable ellipticity.

[0024] Therefore, in the embodiments of the present application, a design method and device for an ellipticity-controllable vector vortex beam based on a metasurface, an electronic device, a storage medium and a program product are provided. The method includes the following steps: decomposing a target light field into a first light field and a second light field with a preset polarization state, the parameters of the first light field and the second light field including multi-degree-of-freedom parameters, thereby realizing the regulation and control of multiple degrees of freedom; determining a first target phase of each position according to the first light field to obtain a first phase map, and determining a second target phase of each position according to the second light field to obtain a second phase map; determining a first rotation angle of each position of the metasurface according to the first target phase of each position in the first phase map to obtain a first phase map, and determining a second rotation angle of each position of the metasurface according to the second target phase of each position in the second phase map to obtain a second phase map; converting the target phase in the phase map into the rotation angle in the phase map; attenuating and merging the first phase map and the second phase map according to the target ellipticity to obtain a metasurface through which a vector vortex beam passes; and determining the metasurface according to the target ellipticity and the two phase maps to realize the regulation and control of the ellipticity. The present application can freely control the ellipticity of the perfect vector vortex beam under the premise that other degrees of freedom are independently adjustable.

[0025] The method for designing an ellipsoidal degree controllable vector vortex beam based on a super-structured surface provided in the embodiments of the present application relates to the field of information technology. The method for designing an ellipsoidal degree controllable vector vortex beam based on a super-structured surface provided in the embodiments of the present application can be applied to a terminal, can also be applied to a server, and can further be software running in the terminal or the server. In some embodiments, the terminal can be a smart phone, a tablet computer, a notebook computer, a desktop computer, a smart speaker, a smart watch, a vehicle-mounted terminal, and the like, but is not limited thereto; the server end can be configured as a stand-alone physical server, can also be configured as a server cluster or a distributed system formed by multiple physical servers, can further be configured as a cloud server providing basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communication, middleware services, domain name services, security services, CDNs, and big data and artificial intelligence platforms, and the server can also be a node server in a blockchain network; and the software can be an application for implementing the method for designing an ellipsoidal degree controllable vector vortex beam based on a super-structured surface, and the like, but is not limited to the above forms.

[0026] The present application can be used in many general or special computer system environments or configurations. For example: personal computers, server computers, handheld or portable devices, tablet devices, multiprocessor systems, microprocessor-based systems, set-top boxes, programmable consumer electronics, network PCs, minicomputers, mainframe computers, distributed computing environments including any of the above systems or devices, and the like. The present application can be described in the general context of computer-executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, and the like that perform specific tasks or implement specific abstract data types. The present application can also be practiced in a distributed computing environment, in which tasks are performed by remote processing devices connected by a communication network. In a distributed computing environment, program modules can be located in local and remote computer storage media, including storage devices.

[0027] It should be noted that in each specific embodiment of the present application, when relevant processing needs to be performed according to user information, user behavior data, user historical data, and user location information and other data related to the identity or characteristics of the user, the user's permission or consent will be obtained first, and the collection, use, and processing of the data will comply with relevant laws, regulations, and standards. In addition, when the embodiments of the present application need to obtain sensitive personal information of the user, the separate permission or separate consent of the user will be obtained through a pop-up window or a jump to a confirmation page, and after obtaining the separate permission or separate consent of the user, the necessary user-related data for enabling the embodiments of the present application to normally operate will be obtained.

[0028] Figure 1is an optional flowchart of a method for designing an ellipsoidal degree controllable vector vortex beam based on a metasurface provided by the present application, Figure 1 The method in the method can include, but is not limited to, steps S101 to S104.

[0029] Step S101, obtaining a target light field of a vector vortex beam, decomposing the target light field into a first light field and a second light field with a preset polarization state; the parameters of the first light field and the second light field both include multi-degree-of-freedom parameters; Step S102, determining a first target phase of each position according to the first light field to obtain a first phase map; determining a second target phase of each position according to the second light field to obtain a second phase map; Step S103, determining a first rotation angle of each position of the metasurface according to the first target phase of each position of the first phase map to obtain a first phase map; determining a second rotation angle of each position of the metasurface according to the second target phase of each position of the second phase map to obtain a second phase map; Step S104, obtaining a target ellipsoidal degree, attenuating and merging the first phase map and the second phase map according to the target ellipsoidal degree to obtain a metasurface through which the vector vortex beam passes.

[0030] The target light field is determined according to actual application requirements, one of the first light field and the second light field is determined autonomously, and the other light field is determined according to the target light field and the determined light field. According to the parameters (such as topological charge, polarization mode, amplitude distribution, and ellipsoidal degree) of the required perfect vector vortex beam, the target light field is set, the target light field is decomposed into two perfect vortex beams with a set polarization state, which are marked as the first light field A1(x, y) and the second light field A2(x, y) respectively. Then, the target phase corresponding to each position is calculated according to the light field to determine the phase map, and the rotation angle is calculated according to the target phase of each position in the phase map to determine the phase map, and finally, the metasurface is determined according to the target ellipsoidal degree and the two phase maps.

[0031] In some embodiments, referring to Figure 2 The target light field is decomposed into a first light field and a second light field with a preset polarization state, including: Step S201, determining the first light field containing preset target parameters according to the preset polarization state; the target parameters include a preset light beam amplitude, a starting phase, a radius, a topological charge, and an imaging position; Step S202, determining the second light field according to the target light field and the first light field; the topological charge of the second light field is obtained by preset adjustment of the topological charge of the first light field.

[0032] The light field is adjusted by target parameters such as preset beam amplitude, initial phase, radius, topological charge and imaging position. A first light field is preset, and a second light field is calculated according to the first light field and a target light field.

[0033] The first light field distribution of the preset perfect vortex is as follows:

[0034] At this time, let the beam amplitude (A), the initial phase ( ), the radius ( r ), the topological charge (l) and the imaging position (z). The second light field distribution with a perfect vortex needs to make preset adjustment of the topological charge according to the first light field distribution to correspond to the design of the perfect vector vortex beam.

[0035] In some embodiments, referring to Figure 3 , the first target phase of each position is determined according to the first light field, and a first phase map is obtained; the second target phase of each position is determined according to the second light field, and a second phase map is obtained, including: Step S301, Fourier transform is performed on the first light field, the first target phase is extracted according to the first light field after Fourier transform, and a first phase map is obtained; Step S302, Fourier transform is performed on the second light field, the second target phase is extracted according to the second light field after Fourier transform, and a second phase map is obtained.

[0036] Fourier holographic calculation: using angular spectrum diffraction theory or Fourier inversion method, the frequency domain wave front information corresponding to each of the two target light fields is converted into the complex amplitude distribution on the Fourier plane thereof, and the first light field distribution after Fourier transform is as follows:

[0037] The second light field distribution after Fourier transform is as follows:

[0038] The first target phase is extracted from it: , and the second target phase is: , where represents Fourier inverse transform.

[0039] In some embodiments, referring to Figure 4 , the first rotation angle of each position of the metasurface is determined according to the first target phase of each position of the first phase map, and a first phase map is obtained; the second rotation angle of each position of the metasurface is determined according to the second target phase of each position of the second phase map, and a second phase map is obtained, including: Step S401, determining a first angle size according to the first target phase of each position of the first image and a preset angle calculation formula, determining a first rotation angle of each position of the metasurface according to the first angle size and a first preset rotation direction, and obtaining a first phase map; Step S402, determining a second angle size according to the second target phase of each position of the second image and a preset angle calculation formula, determining a second rotation angle of each position of the metasurface according to the second angle size and a second preset rotation direction, and obtaining a second phase map.

[0040] Q-B phase encoding mapping: Since the metasurface controls the output light field phase through P-B phase, the above phase distribution needs to be converted into the rotation angle θ(x, y) of the nanostructure, satisfying the relationship between P-B phase and rotation angle:

[0041] Where "+" represents clockwise rotation, which is used for right-handed incident light, "-" represents counterclockwise rotation, which is used for left-handed incident light. According to the above formula, two rotation angle maps suitable for left and right circularly polarized light can be obtained, that is, the phase distribution map of the perfect vector vortex beam with controllable ellipticity.

[0042] In some embodiments, referring to Figure 5 , the first phase map and the second phase map are attenuated and combined according to the target ellipticity to obtain a metasurface through which a vector vortex beam passes, including: Step S501, calculating the proportion of the first phase map according to the target ellipticity and a preset proportion calculation formula, and randomly attenuating the first phase map according to the proportion; Step S502, barb attenuation of the second phase map according to the position of the random attenuation of the first phase map; Step S503, combining the attenuated first phase map and the attenuated second phase map to obtain a metasurface through which a vector vortex beam passes.

[0043] Spatial matching and integration preparation: Two independent metasurface phase design maps have been completed. In order to finally integrate into a single-layer metasurface pattern and realize adjustable control of ellipticity, preparation is needed for subsequent "random barb attenuation", that is, a pixel-level mask map is constructed for each map, which is used for staggered layout of nanostructures with different polarization responses.

[0044] By introducing the ratio of left-handed circularly polarized light and right-handed circularly polarized light to control the ellipticity χ of the light field, the ratio of left-handed circularly polarized light and right-handed circularly polarized light can be flexibly adjusted by removing a certain proportion of clockwise rotating nanorods or counterclockwise rotating nanorods as needed. When the number of clockwise rotating nanorods and counterclockwise rotating nanorods is equal, the intensity of right-handed circularly polarized light and left-handed circularly polarized light of the transmitted light field is equal, and the proportion B = 50; if all are clockwise rotating nanorods, the transmitted field is all left-handed circularly polarized light, and the proportion B = 0; if all are counterclockwise rotating nanorods, the transmitted field is all right-handed circularly polarized light, and the proportion B = 100. While not damaging the image picture, that is, not damaging the quality of other degrees of freedom of the perfect vector vortex beam, the random Babinet attenuation technique needs to be used for integration of the two holograms. The ellipticity can only be between 0 and 1, and when the ellipticity is 0, the beam can only have various linear polarizations, which are usually radial or angular polarizations; when the ellipticity is 1, the beam is circularly polarized.

[0045] The obtained two perfect vortex beam generating metasurfaces are randomly Babinet attenuated, that is, one metasurface is randomly attenuated to a B% metasurface of the original nanorod. Assuming that the resolution of the metasurface is 180*180, the B% pixels are randomly set to be blank, and their positions are recorded; the other metasurface selects the positions recorded in the first image hologram, that is, the positions of the first metasurface set to be blank, and all the pixels except the recorded positions are set to be blank, that is, Babinet attenuation, and the attenuation degree is 1-B%. The P-B phase required by the two metasurfaces is integrated into a complete P-B phase, which is the complete P-B phase required for the metasurface to generate a perfect vector vortex beam. Since the random Babinet attenuation technique is used, there is no overlap when the two metasurfaces are superimposed, and there is no blank position, and the final resolution is still the originally set pixel. When the incident beam of the metasurface is adjusted to be uniform linear polarization, the linear polarization can be considered as the superposition of left-handed circularly polarized light and right-handed circularly polarized light, therefore, the two holograms work simultaneously. The ellipticity of the perfect vector vortex beam obtained can be checked by using a polarizer in the cross direction of the incident linearly polarized light or using a Stokes parameter instrument to screen the light field.

[0046] In some embodiments, referring to Figure 6 , the preset proportion calculation formula is determined by the following method, comprising: Step S601, calculating a difference expression and a sum expression of the first preset rotation direction circularly polarized light and the second preset rotation direction circularly polarized light according to the proportion; Step S602, determining the preset proportion calculation formula according to the difference expression, the sum expression, and the target ellipticity.

[0047] The calculation formula of the light field ellipticity χ can be as follows:

[0048] wherein, e R is a unit vector of right-handed circularly polarized light, e L is a unit vector of left-handed circularly polarized light, and e R = e L =1.

[0049] The present patent generates perfect vortex beams through metasurface holographic technology. By splitting a preset perfect vector vortex beam into two perfect vortex beams with the same resolution and performing holographic calculation, the information images of the two perfect vortex beams are obtained, and the beam amplitude, polarization mode, starting phase, radius, orbital angular momentum, imaging position corresponding numerical values are given in the preset while controlling the ellipticity of the beam. The relationship between the topological charge number of the perfect vector vortex beam l and the topological charge numbers of the two perfect vortex beams after splitting l 1 and l 2 is: l ( l 1+ l 2) / 2. The relationship between the polarization order m of the perfect vector vortex beam and the topological charge numbers of the two perfect vortex beams after splitting l 2 and l 2 is: m=( l 1- l 2) / 2.

[0050] Referring to Figure 7 , a first phase map (metasurface 1) is determined according to a first light field, a second phase map (metasurface 2) is determined according to a second light field, the metasurface 1 is randomly attenuated, the metasurface 2 is attenuated according to the attenuated metasurface 1, and then the attenuated metasurface 1 and the metasurface 2 are combined to obtain a final metasurface. Referring to Figure 8 , Figure 8 , a conceptual diagram of the experimental results of the perfect vector vortex beam obtained during testing and the change with the increase of the transmission distance is shown. Within a certain distance range of the metasurface, a perfect vector vortex beam is formed, and with the increase of the distance, it becomes an ordinary vortex beam. Referring to Figure 9 , Figure 9 , a simulation result of a perfect vector vortex beam obtained during testing of an embodiment is shown. The arrow on the beam indicates the polarization state, and the arrow in the upper right corner represents the polarization detection direction. Figure 9 , (a) in the figure is a perfect vector vortex beam with an ellipticity of 0, Figure 9 , (b) in the figure is a perfect vector vortex beam with an ellipticity of χ=0.5 (B=75). Figure 9 , (a) andFigure 9 The left column of (b) is the result of circularly polarized incidence, and the right column is the result of horizontally linearly polarized incidence and vertically polarized detection.

[0051] According to the P-B phase distribution of the perfect vector vortex beam finally obtained, an ultrathin surface is made by using a quartz piece on which an amorphous silicon film with a thickness of 350 nm is grown. A spatial light path is built, a specific wavelength and linearly polarized laser is used to be incident on the sample from the side of the quartz substrate, a quarter-wave plate and a linear polarizer are combined to extract the light field component orthogonal to the incident polarization and along the z-axis. Finally, a lens group is used to project the imaging plane of the sample onto the CCD, and the image formed is observed. Finally, an ellipticity-controllable perfect vector vortex beam is obtained at a predetermined distance z from the ultrathin surface, and with the increase of the transmission distance, the multi-degree-of-freedom perfect vector vortex beam quickly dissipates and evolves into an ordinary vortex. The ellipticity of the perfect vortex field obtained is confirmed by polarization detection or using a polarization detector. At the same time, the multiple degrees of freedom of the perfect vector vortex beam generated by this method are orthogonal to each other and can be independently controlled.

[0052] In a specific embodiment, the sample preparation process is as follows.

[0053] Cleaning of the quartz piece: first, a quartz piece with an area of about 1.5 cm*1.5 cm is cut, and then it is immersed in a solution with a volume ratio of concentrated H2SO4 to hydrogen peroxide of 3:1 for 10 minutes. After taking it out, it is passed through two deionized water, and then it is ultrasonically cleaned in the order of acetone-isopropyl alcohol-deionized water for 10 minutes each. Finally, it is taken out and dried.

[0054] Growth of amorphous silicon on the quartz piece: an inductively coupled plasma chemical vapor deposition system (ICPCVD) is used to grow an amorphous silicon film with a thickness of 350 nm on the upper layer of the quartz piece.

[0055] Glue spinning: a 200 nm thick photoresist hydrogen silsesquioxane is spun on the surface of the single crystal silicon layer at a speed of 4000 r / min. A hot plate at 90 degrees Celsius is used to bake for 3 minutes to solidify the photoresist.

[0056] Aluminum plating: in order to enhance the conductivity of the substrate, a sputtering instrument is used to plate a layer of aluminum with a thickness of about 30 nm on the sample after the glue spinning.

[0057] Electron beam exposure: an electron beam direct writing device is used to write the patterns on the layout to the substrate.

[0058] Developing: after exposure, the piece is immersed in a TMAH solution for 2 minutes, and then it is taken out and immersed in deionized water for 1 minute to remove the excess developing solution.

[0059] Etching: The parts of the un-written structure were etched away using an inductively coupled plasma etching system (PlasmaPro System 100 ICP180). Finally, the metasurface sample with the designed structure was obtained.

[0060] Please refer to Figure 10 The embodiment of the present application also provides a metasurface-based ellipsoidal degree controllable vector vortex beam design device, which can realize the above method. The device comprises: A decomposition module is configured to obtain a target light field of a vector vortex beam, and decompose the target light field into a first light field and a second light field with preset polarization states. The parameters of the first light field and the second light field both include multi-degree-of-freedom parameters. An image map determination module is configured to determine a first target phase of each position according to the first light field, and obtain a first image map; and determine a second target phase of each position according to the second light field, and obtain a second image map. A phase map determination module is configured to determine a first rotation angle of each position of the metasurface according to the first target phase of each position of the first image map, and obtain a first phase map; and determine a second rotation angle of each position of the metasurface according to the second target phase of each position of the second image map, and obtain a second phase map. A metasurface determination module is configured to obtain a target ellipsoidal degree, and perform attenuation and merging on the first phase map and the second phase map according to the target ellipsoidal degree, and obtain a metasurface through which the vector vortex beam passes.

[0061] It can be understood that the contents in the above method embodiments are all applicable to the present device embodiments. The present device embodiments specifically realize the same functions as the above method embodiments, and achieve the same beneficial effects as the above method embodiments.

[0062] The embodiment of the present application also provides an electronic device. The electronic device comprises a memory and a processor. The memory stores a computer program. The processor realizes the above method when executing the computer program. The electronic device can be any intelligent terminal such as a tablet computer or a vehicle-mounted computer.

[0063] It can be understood that the contents in the above method embodiments are all applicable to the present device embodiments. The present device embodiments specifically realize the same functions as the above method embodiments, and achieve the same beneficial effects as the above method embodiments.

[0064] Please refer to Figure 11 , Figure 11 The hardware structure of the electronic device of another embodiment is illustrated, and the electronic device comprises: The processor 101 can be implemented by a general-purpose CPU (Central Processing Unit), a microprocessor, an ASIC (Application Specific Integrated Circuit), or one or more integrated circuits, and is configured to execute related programs to implement the technical solutions provided by the embodiments of the present application. The memory 102 can be implemented by a ROM (Read Only Memory), a static storage device, a dynamic storage device, or a RAM (Random Access Memory), and the like. The memory 102 can store an operating system and other application programs. When the technical solutions provided by the embodiments of the present application are implemented by software or firmware, the related program codes are stored in the memory 102 and are called and executed by the processor 101 to implement the above-mentioned method of the embodiments of the present application. The input / output interface 103 is configured to implement information input and output. The communication interface 104 is configured to implement the communication interaction between the device and other devices. The communication can be implemented by a wired manner (for example, a USB, a network cable, or the like) or a wireless manner (for example, a mobile network, WIFI, Bluetooth, or the like). The bus 105 is configured to transmit information between various components (for example, the processor 101, the memory 102, the input / output interface 103, and the communication interface 104) of the device. The processor 101, the memory 102, the input / output interface 103, and the communication interface 104 are connected to each other by the bus 105 to realize the communication connection between the device.

[0065] The embodiments of the present application further provide a computer readable storage medium, which stores a computer program. The computer program is executed by a processor to implement the above-mentioned method.

[0066] It can be understood that the above-mentioned method embodiments are applicable to the storage medium embodiments, the storage medium embodiments specifically implement the functions of the above-mentioned method embodiments, and achieve the same beneficial effects as the above-mentioned method embodiments.

[0067] The embodiments of the present application further provide a computer program product, which includes a computer program. The computer program is executed by a processor to implement the above-mentioned method.

[0068] It can be understood that the contents in the above method embodiments are all applicable to the program product embodiments, the program product embodiments specifically implement the functions same as those of the above method embodiments, and achieve the same beneficial effects as those of the above method embodiments.

[0069] The memory, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs and non-transitory computer-executable programs. In addition, the memory can include a high-speed random access memory and can also include a non-transitory memory, such as at least one magnetic disk storage device, a flash memory device, or other non-transitory solid-state memory device. In some embodiments, the memory can optionally include a memory remotely arranged relative to the processor, and these remote memories can be connected to the processor through a network. Examples of the above network include but are not limited to the Internet, an intranet, a local area network, a mobile communication network, and a combination thereof.

[0070] The application provides a design method and device for an ellipsoidal degree controllable vector vortex beam based on a super-structured surface, an electronic device, a storage medium and a program product. The method includes the following steps: decomposing a target light field into a first light field and a second light field with a preset polarization state, the parameters of the first light field and the second light field both including multi-degree-of-freedom parameters, so as to realize the regulation and control of the multi-degree-of-freedom; determining a first target phase of each position according to the first light field to obtain a first phase map, determining a second target phase of each position according to the second light field to obtain a second phase map, determining a first rotation angle of each position of the super-structured surface according to the first target phase of each position of the first phase map to obtain a first phase map, determining a second rotation angle of each position of the super-structured surface according to the second target phase of each position of the second phase map to obtain a second phase map, converting the target phase in the phase map into the rotation angle in the phase map, and attenuating and merging the first phase map and the second phase map according to a target ellipsoidal degree to obtain a super-structured surface through which a vector vortex beam passes, and determining the super-structured surface according to the target ellipsoidal degree and the two phase maps to realize the regulation and control of the ellipsoidal degree.

[0071] The embodiments described in the embodiments of the application are used to more clearly illustrate the technical solutions of the embodiments of the application, and do not constitute a limitation on the technical solutions provided by the embodiments of the application. Those skilled in the art can know that, with the evolution of technology and the appearance of new application scenarios, the technical solutions provided by the embodiments of the application are also applicable to similar technical problems.

[0072] Those skilled in the art can understand that the technical solutions shown in the figures do not constitute a limitation on the embodiments of the application, and can include more or fewer steps than those shown in the figures, or combine certain steps or different steps.

[0073] The apparatus embodiments described above are merely exemplary, and the units described as separate units can or can not be physically separate, i.e., can be located in one place, or can be distributed over multiple network units. Part or all of the modules can be selected according to actual needs to achieve the purpose of the embodiment.

[0074] Those skilled in the art can understand that all or some of the steps in the method disclosed above, the functional modules / units in the system and the device can be implemented as software, firmware, hardware and appropriate combinations thereof.

[0075] The terms "first", "second", "third", "fourth" and the like in the description of the application and in the claims of the foregoing drawings, if any, are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the use of the terms so construed can be interchanged, such that the embodiments of the application described herein can be carried out in other than the order discussed herein without departing from the scope of the application. Further, the terms "comprise" and "comprising" and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, product or apparatus that comprises a list of steps or units does not necessarily comprise only those steps or units but can include other not expressly listed steps or units.

[0076] It should be understood that in the present application, "at least one" means one or more, and "multiple" means two or more. "And / or" is used to describe the relationship between the associated objects, which means that there can be three relationships, for example, "A and / or B" can mean that there are three cases: only A, only B, and A and B at the same time, where A and B can be singular or plural. The character " / " generally represents that the associated objects before and after are in an "or" relationship. "At least one of the following" or the like means any combination of these items, including any combination of single or multiple items. For example, at least one of a, b or c can mean a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0077] In several embodiments provided in the present application, it should be understood that the disclosed apparatus and method can be implemented by other manners. For example, the apparatus embodiments described above are merely illustrative, for example, the division of the above units is merely a logical function division, and actual implementation can have another division manner, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units or components shown or discussed can be indirect coupling or communication connection through some interfaces, apparatuses or units, and can be electrical, mechanical or other forms.

[0078] The units described above as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, i.e., they can be located in one place or distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the embodiment.

[0079] In addition, the functional units in each embodiment of the present application can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or in the form of a software functional unit.

[0080] If the integrated unit is realized in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application essentially or the part of the prior art that makes a contribution or the whole or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium, including a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method of each embodiment of the present application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and various program storage media.

[0081] The preferred embodiments of the embodiments of the present application are described above with reference to the accompanying drawings, but this does not limit the scope of the embodiments of the present application. Any modifications, equivalent replacements and improvements made by those skilled in the art without departing from the scope and essence of the embodiments of the present application shall be within the scope of the embodiments of the present application.

Claims

1. A method for designing ellipticity-controllable vector vortex beams based on metasurfaces, characterized in that, The method includes the following steps: The target optical field of the vector vortex beam is obtained, and the target optical field is decomposed into two optical fields with preset polarization states: a first optical field and a second optical field; the parameters of the first optical field and the second optical field both include multi-degree-of-freedom parameters. The first target phase at each position is determined based on the first light field to obtain a first hologram; the second target phase at each position is determined based on the second light field to obtain a second hologram. The first rotation angle at each position of the metasurface is determined based on the first target phase at each position of the first hologram to obtain a first phase map; the second rotation angle at each position of the metasurface is determined based on the second target phase at each position of the second hologram to obtain a second phase map; The target ellipticity is obtained, and the first phase map and the second phase map are attenuated and merged according to the target ellipticity to obtain the metasurface through which the vector vortex beam passes.

2. The method according to claim 1, characterized in that, The step of decomposing the target light field into two light fields, a first light field and a second light field, each with a preset polarization state, includes: A first optical field containing preset target parameters is determined based on the preset polarization state; the target parameters include preset beam amplitude, initial phase, radius, topological charge, and imaging position; The second light field is determined based on the target light field and the first light field; the topological charge of the second light field is obtained by pre-setting and adjusting the topological charge of the first light field.

3. The method according to claim 1, characterized in that, The first target phase at each position is determined based on the first light field to obtain the first image map; The second target phase at each position is determined based on the second light field, resulting in a second image map, including: Perform a Fourier transform on the first light field, and extract the phase of the first target based on the first light field after the Fourier transform to obtain the first image map; Perform a Fourier transform on the second light field, extract the phase of the second target from the transformed second light field, and obtain the second image map.

4. The method according to claim 1, characterized in that, The first rotation angle at each position of the metasurface is determined based on the first target phase at each position of the first image map to obtain the first phase map; Based on the second target phase at each position of the second phase map, the second rotation angle at each position of the metasurface is determined, resulting in a second phase map, including: The first angle is determined according to the first target phase and the preset angle calculation formula at each position of the first image map, and the first rotation angle at each position of the metasurface is determined according to the first angle and the first preset rotation direction to obtain the first phase map; The second angle magnitude is determined based on the second target phase at each position of the second phase map and the preset angle calculation formula. The second rotation angle at each position of the metasurface is determined based on the second angle magnitude and the second preset rotation direction to obtain the second phase map.

5. The method according to claim 1, characterized in that, The step of attenuating and merging the first phase map and the second phase map according to the target ellipticity to obtain the metasurface through which the vector vortex beam passes includes: The proportion of the first phase image is calculated according to the target ellipticity and the preset ratio calculation formula, and the first phase image is randomly attenuated according to the proportion. The second phase map is attenuated in Babinette manner according to the position of random attenuation of the first phase map; The attenuated first phase map and the attenuated second phase map are combined to obtain the metasurface through which the vector vortex beam passes.

6. The method according to claim 5, characterized in that, The preset ratio calculation formula is determined by the following methods, including: Calculate the difference expression and sum expression between the circularly polarized light with the first preset rotation direction and the circularly polarized light with the second preset rotation direction based on the stated proportion; The preset ratio calculation formula is determined based on the difference expression, the sum expression, and the target ellipticity.

7. A device for designing an ellipticity-controllable vector vortex beam based on a metasurface, characterized in that, The device includes: The decomposition module is used to acquire the target light field of the vector vortex beam and decompose the target light field into two light fields, a first light field and a second light field, each with a preset polarization state; the parameters of the first light field and the second light field both include multi-degree-of-freedom parameters. The image symmetry determination module is used to determine the first target phase at each position based on the first light field to obtain a first image symmetry; and to determine the second target phase at each position based on the second light field to obtain a second image symmetry. The phase map determination module is used to determine the first rotation angle of each position of the metasurface based on the first target phase at each position of the first hologram to obtain a first phase map; and to determine the second rotation angle of each position of the metasurface based on the second target phase at each position of the second hologram to obtain a second phase map. The metasurface determination module is used to obtain the target ellipticity, and to attenuate and merge the first phase map and the second phase map according to the target ellipticity to obtain the metasurface through which the vector vortex beam passes.

8. An electronic device, characterized in that, include: At least one processor; At least one memory for storing at least one program; When the at least one program is executed by the at least one processor, the at least one processor implements the method as described in any one of claims 1-6.

9. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the method of any one of claims 1 to 6.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the method of any one of claims 1 to 6.

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