Lens and Its Manufacturing Method and Use

Abstract

Method for manufacturing a lens, comprising: setting the numerical value of the topological charge number of the orbital angular momentum to be detected M ; setting the numerical value of the target electric field intensity at the n -th pixel point of the receiving plane for the vortex electromagnetic wave with different topological charge numbers; calculating the electric field intensity at the n -th pixel point of the receiving plane when the vortex electromagnetic wave with different topological charge numbers is projected; using a loss function to gradually approximate and optimize the phase distribution of the lens; and manufacturing the lens using the obtained phase distribution of the lens. The lens manufactured by this manufacturing method is beneficial to reducing the cost of detecting the topological charge number of the orbital angular momentum of the vortex electromagnetic wave. In addition, a lens and its use are also provided.

Description

Technical Field

[0001] The present invention relates to a lens, and particularly to a lens for detecting the topological charge number of the orbital angular momentum of a vortex electromagnetic wave, and a manufacturing method and use thereof. Background Art

[0002] The orbital angular momentum (OAM) of an electromagnetic wave is independent of the electric field strength and can constitute a new dimension for wireless transmission. By using this new dimension, the transmission capacity can be greatly improved. The electromagnetic wave with OAM is also called a "vortex electromagnetic wave".

[0003] The vortex electromagnetic wave carrying orbital angular momentum provides a new degree of freedom for applications such as particle manipulation, communication, signal detection, and quantum communication. Physically, infinitely orthogonal OAM modes (the OAM mode is the topological charge number of the orbital angular momentum) can be transmitted simultaneously in free space without interference, which makes OAM multiplexing a very promising technology and has important research significance for various fields of communication, medical treatment, and signal detection. As the key to OAM-based applications, OAM mode detection has become a research hotspot in recent years.

[0004] In recent years, there have been many studies on the accurate detection of OAM modes. Similar to the generation of the vortex electromagnetic wave carrying OAM, the spiral phase plate (SPP) is the most direct method for detecting OAM modes. However, in this method, one SPP can only detect one OAM mode OAM wave of OAM at a specific frequency. To detect the vortex electromagnetic wave carrying OAM of different modes, different SPPs need to be replaced, so the cost is relatively high. Plane wave interference is another method for detecting the vortex electromagnetic wave carrying OAM. By analyzing the interference pattern generated by the interference between the reference plane wave and the vortex electromagnetic wave carrying OAM, the OAM mode can be obtained. However, this method is not only complex but also difficult to obtain accurate results. Summary of the Invention

[0005] The object of the present invention is to provide a manufacturing method of a lens, and the lens obtained by this manufacturing method is beneficial to reducing the cost of detecting the topological charge number of the orbital angular momentum of a vortex electromagnetic wave.

[0006] Another object of the present invention is to provide a lens, which is beneficial to reducing the cost of detecting the topological charge number of the orbital angular momentum of a vortex electromagnetic wave.

[0007] Another object of the present invention is to provide a use of a lens for detecting the topological charge number of the orbital angular momentum of a vortex electromagnetic wave, and its detection cost is relatively low.

[0008] The manufacturing method of the lens provided by the present invention, wherein the lens is used to detect the topological charge number of the orbital angular momentum of the vortex electromagnetic wave. The lens has K dielectric columns, and K is a positive integer. During detection, the vortex electromagnetic wave passes through the lens and propagates in free space and then projects onto a receiving plane, and the receiving plane has N pixel points, and N is a positive integer.

[0009] The manufacturing method of the lens includes: setting the numerical values of the topological charge numbers m of M orbital angular momenta to be detected, where M is a positive integer and m is an integer from -10 to 10. Setting the target electric field intensity at the nth (n = 1, 2, 3... N) pixel point of the receiving plane for the vortex electromagnetic wave with different topological charge numbers m of the numerical value. Calculating the electric field intensity at the nth pixel point of the receiving plane when the vortex electromagnetic wave with different topological charge numbers m projects onto the receiving plane wherein, the phase of the complex transmission coefficient of the lens at the kth (k = 1, 2, 3... K) dielectric column is a variable. Using the following loss function, gradually approaching and optimizing the phase distribution of the lens, Manufacturing the lens using the obtained phase distribution of the lens.

[0010] The manufacturing method of the lens of the present invention is conducive to reducing the cost of detecting the topological charge number of the orbital angular momentum of the vortex electromagnetic wave.

[0011] In another schematic embodiment of the manufacturing method of the lens, the step of calculating the electric field intensity at the nth pixel point of the receiving plane when the vortex electromagnetic wave with different topological charge numbers m projects onto the receiving plane specifically includes: calculating the electric field intensity E k , E k of the vortex electromagnetic wave passing through the kth dielectric column of the lens and propagating in free space and then outputting to the nth pixel point of the receiving plane. The calculation formula of E k = w k t l e k , where, w k is the transfer function of free space, t k is the complex transmission coefficient of the lens at the kth dielectric column, and e k is the incident electric field intensity of the vortex electromagnetic wave incident on the kth dielectric column; calculating the electric field intensity at the nth pixel point of the receiving plane when the vortex electromagnetic wave passes through all the dielectric columns of the lens and propagates in free space and then outputs where This is conducive to improving the accuracy of topological charge number detection.

[0012] In still another schematic embodiment of the manufacturing method of the lens, the calculation formula of w k is:

[0013] Among them, d is the distance from the receiving plane to the lens, λ is the wavelength of the vortex electromagnetic wave in vacuum, and r is the distance between the k-th dielectric column and the n-th pixel point on the receiving plane. This helps to improve the accuracy of topological charge number detection.

[0014] In another illustrative embodiment of the method for manufacturing the lens, the distance d from the receiving plane to the lens is 20 mm to 60 mm. This helps to improve the accuracy of topological charge number detection.

[0015] In still another illustrative embodiment of the method for manufacturing the lens, t k The calculation formula of is: Among them, a k Is the amplitude of the complex transmission coefficient, and the value is 1. Is the phase of the complex transmission coefficient. This helps to improve the accuracy of topological charge number detection.

[0016] In another illustrative embodiment of the method for manufacturing the lens, e k The calculation formula of is: e k = e jmθ , where: m is the topological charge number of the orbital angular momentum of the vortex electromagnetic wave, θ is the azimuth angle of the vortex electromagnetic wave in the coordinate plane of the lens, θ = arctan(y k / x k ), x k And y k Are the coordinates of the k-th dielectric column in the coordinate plane of the lens. This helps to improve the accuracy of topological charge number detection.

[0017] In still another illustrative embodiment of the method for manufacturing the lens, the step of setting the target electric field intensity Of the n-th pixel point on the receiving plane for vortex electromagnetic waves with different topological charge numbers m, specifically: select several pixel points gathered in one area on the receiving plane and set its Value to the first value, and set the Value of the remaining pixel points to a second value different from the first value, where, for different topological charge numbers m, The pixel points whose values are set to the first value are different from each other. This facilitates the identification of different topological charge numbers on the receiving plane.

[0018] In still another illustrative embodiment of the method for manufacturing the lens, the step of manufacturing the lens by using the obtained phase distribution of the lens specifically includes: calculating the height of each dielectric column of the lens according to the phase distribution of the lens and the linear relationship between the phase angle and the height of the dielectric column; and manufacturing the lens by 3D printing technology according to the calculated height of each dielectric column of the lens. This helps to reduce the manufacturing cost of the lens.

[0019] In still another exemplary embodiment of the method for manufacturing a lens, the frequency range of the vortex electromagnetic wave is from 100 GHz to 300 GHz.

[0020] The present invention further provides a lens manufactured by the above-described method for manufacturing a lens. This lens is conducive to reducing the cost of detecting the topological charge number of the orbital angular momentum of the vortex electromagnetic wave.

[0021] In another exemplary embodiment of the lens, the period of the dielectric columns of the lens is from 0.5 mm to 2 mm, and the number of dielectric columns is from 900 to 14,884. This is conducive to improving the accuracy of topological charge number detection.

[0022] The present invention further provides a use of the above lens for detecting the topological charge number of the orbital angular momentum of the vortex electromagnetic wave. During detection, the vortex electromagnetic wave is allowed to pass through the lens and propagate in free space and then projected onto the receiving plane, and then the topological charge number m of the orbital angular momentum of the vortex electromagnetic wave is determined according to the electric field intensity distribution on the receiving plane and the numerical values of the target electric field intensities of the pixels on the receiving plane for the vortex electromagnetic waves with different topological charge numbers m. This is conducive to reducing the cost of detecting the topological charge number of the orbital angular momentum of the vortex electromagnetic wave. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The following drawings only schematically illustrate and explain the present invention and do not limit the scope of the present invention.

[0024] Figure 1 For illustrating the method of using a lens to detect the topological charge number of the orbital angular momentum of the vortex electromagnetic wave.

[0025] Figure 2 It is a flowchart of an exemplary embodiment of the method for manufacturing a lens.

[0026] Figure 3 For illustrating the method of manufacturing a lens, wherein (a) is a loss function curve graph, (b) is a phase distribution graph of the lens, (c) is a relationship curve graph between the transmission phase angle and the height of the dielectric column, and (d) is an electromagnetic simulation model graph of the lens.

[0027] Figure 4 It is a theoretical result graph of using a lens to detect the topological charge number of the orbital angular momentum of the vortex electromagnetic wave.

[0028] Figure 5 It is an electromagnetic simulation result graph of using a lens to detect the topological charge number of the orbital angular momentum of the vortex electromagnetic wave.

[0029] Figure 6 It is an experimental result graph of using a lens to detect the topological charge number of the orbital angular momentum of the vortex electromagnetic wave.

[0030] Figure 7For illustrating a detection area predefined in a receiving plane in an exemplary embodiment.

[0031] Description of symbols

[0032] 30 Vortex electromagnetic waves

[0033] 40 Lens

[0034] 41kth medium column

[0035] 50 receiving plane

[0036] 51nth pixel

[0037] 52 detection areas

[0038] A optical axis. DETAILED DESCRIPTION

[0039] In order to have a clearer understanding of the technical features, purposes and effects of the invention, the specific embodiments of the present invention are now described with reference to the accompanying drawings. The same reference numerals in the drawings represent components with the same structure or similar structures but the same functions.

[0040] In this document, “exemplary” means “serving as an example, instance or illustration”, and any diagram or implementation described in this document as “exemplary” should not be interpreted as a more preferred or more advantageous technical solution.

[0041] In order to simplify the drawings, each figure only schematically shows the parts related to the present invention, which do not represent the actual structure of the product.

[0042] The present invention provides a method for manufacturing a lens, wherein the lens is used to detect the topological charge of the orbital angular momentum of a vortex electromagnetic wave. Specifically, for example, different topological charges of the orbital angular momentum are detected in the sub-terahertz frequency band, and the sub-terahertz frequency band ranges from 100 GHz to 300 GHz.

[0043] Figure 1 It is used to illustrate the method of using the lens of the present invention to detect the topological charge of the orbital angular momentum of the vortex electromagnetic wave. Figure 1 As shown, the lens 40 and the receiving plane 50 are sequentially arranged along a direction parallel to the optical axis A. In this article, the optical axis refers to the center line of a vortex electromagnetic wave, and the vortex electromagnetic wave rotates around the optical axis.

[0044] Figure 1 The optical path during the detection process is schematically shown, e.g. Figure 1As shown, a vortex electromagnetic wave 30 with a topological charge number of m is transmitted to a lens 40. One side of the lens 40 is, for example, a plane perpendicular to the optical axis A, and the other side is evenly distributed with K dielectric columns. When the vortex electromagnetic wave 30 passes through the dielectric columns, diffraction occurs and it is transmitted through free space to a receiving plane 50. The free space is the space between the lens 40 and the receiving plane 50, which is, for example, an air space, a vacuum space, or a similar space.

[0045] Figure 2 It is a flowchart of a schematic embodiment of a method for manufacturing a lens. As Figure 2 shown, the method for manufacturing a lens includes the following steps S1 to S5.

[0046] S1: Set the value of the topological charge number m of M orbital angular momenta to be detected, that is, M is the number of topological charge numbers m, M is a positive integer, and m is, for example, an integer from -10 to 10.

[0047] S2: Set the target electric field intensity at the nth (n = 1, 2, 3... N) pixel of the receiving plane 50 for the vortex electromagnetic wave 30 with different topological charge numbers m where N is the number of pixels of the receiving plane 50, and N is a positive integer.

[0048] Specifically, for example, select several pixels concentrated in an area on the receiving plane 50 and set its value to a first value, and set the value of the remaining pixels to a second value different from the first value. The area where several pixels with the value being the first value are concentrated is a detection area, that is, for several pixels within the detection area, the value is the first value, and the value of the pixels outside the detection area is set to the second value. The detection areas corresponding to different topological charge numbers m are different. For M different topological charge numbers m, M non-overlapping detection areas are set. In the schematic embodiment, the first value is, for example, 1, and the second value is, for example, 0, but it is not limited thereto.

[0049] S3: Calculate the electric field intensity where the phase of the complex transmission coefficient of the kth (k = 1, 2, 3... K) dielectric column of the lens 40 is a variable.

[0050] In the schematic embodiment, the specific calculation steps for the electric field intensity when the vortex electromagnetic wave 30 with different topological charge numbers m is projected onto the nth pixel 51 of the receiving plane 50 include:

[0051] (1) Calculate the electric field strength E of the vortex electromagnetic wave 30 passing through the k-th dielectric column 41 of the lens 40, passing through the lens 40, and propagating in free space and then output to the n-th pixel point 51 of the receiving plane 50. k E k The calculation formula is:

[0052] E k = w k t k e k ;

[0053] Among them, w k is the transfer function of free space. According to Huygens' principle, when the vortex electromagnetic wave 30 encounters the dielectric column, diffraction occurs, and each point on the wavefront can be regarded as a secondary wave source propagating into free space.

[0054] Based on the Rayleigh-Sommerfeld equation, the calculation formula of w k is:

[0055]

[0056] Among them, d is the distance from the receiving plane 50 to the lens 40, specifically, for example, the distance from the receiving plane 50 to the top of the highest dielectric column on the plane of the lens 40. In the illustrative embodiment, the value range of d is 20 mm to 60 mm; λ is the wavelength of the vortex electromagnetic wave 30 in vacuum; r is the distance between the k-th dielectric column and the n-th pixel point of the receiving plane 50. Figure 1 The distance between one of the dielectric columns 41 and one of the pixel points 51 is used to assist in explaining r. In this illustrative embodiment, the transmission amplitude is 1, that is, the vortex electromagnetic wave 30 is completely transmitted from the dielectric column of the lens 40. In other illustrative embodiments, the transmission amplitude can also be other numbers less than 1. At this time, the calculation formula of E k must be superimposed with this transmission amplitude.

[0057] t k is the complex transmission coefficient of the lens 40 at the k-th dielectric column 41. The calculation formula of t k is:

[0058]

[0059] Among them, a k is the amplitude of the complex transmission coefficient, and the value is 1. is the phase of the complex transmission coefficient.

[0060] e k is the incident electric field strength of the vortex electromagnetic wave 30 incident on the k-th dielectric column 41. The calculation formula of e k is:

[0061] e k = e jmθ ;

[0062] Among them, m is the topological charge number of the orbital angular momentum carried by the vortex electromagnetic wave 30, θ is the azimuth angle of the vortex electromagnetic wave 30 in the coordinate plane of the lens 40, θ = arctan(y k / x k ), x k and y k are the coordinates of the k-th dielectric column 41 in the coordinate plane of the lens 40. In this illustrative embodiment, the coordinate plane of the lens 30 is a plane perpendicular to the optical axis A, all dielectric columns intersect with the coordinate plane of the lens, the coordinate system where the coordinate plane of the lens 40 is located takes the perpendicular point of it and the optical axis A as the origin, and the coordinate plane of the lens 40 is located in the plane where the x-y axis is located as shown in Figure 1 shown.

[0063] (2) Calculate the electric field strength of the vortex electromagnetic wave 30 output to the n-th pixel point 51 of the receiving plane 50 after passing through all the dielectric columns of the lens 40 and propagating in free space Among them

[0064] S4: Using the loss function shown below, gradually approximate and optimize the phase distribution of the lens 40

[0065]

[0066] Figure 3 is used to illustrate the manufacturing method of the lens. In the illustrative embodiment, the frequency of the vortex electromagnetic wave 30 is 140 GHz, M is 4, and m are 0, 1, 2, and 3 respectively.

[0067] In Figure 3 , (a) is the curve graph of the loss function. As shown in (a), during the continuous iteration process, set the slope l of the loss function. When l is less than or equal to 0.1, the iteration ends. The calculation formula for the slope l of the loss function is: Among them, L is the loss value, which is the physical quantity represented by the ordinate shown in (a); L max is the maximum loss value, which is the maximum value of the curve shown in (a) on the ordinate; t is the number of iterations, which is the physical quantity represented by the abscissa shown in (a). It can be seen from (a) that when the number of iterations is about 70 times, the loss function curve tends to be flat and the iteration process ends, that is, the phase distribution of the lens 40 is obtained. Figure 3 The (b) of is the phase distribution diagram of the calculated phase distribution of the lens 40. The color bar on the right side of (b) represents the magnitude of the phase angle, and from deep to shallow represents the phase angle changing from 180° to -180°.

[0068] S5: Fabricate the lens 40 using the obtained phase distribution of the lens 40.

[0069] Figure 3 In (c), it is a graph showing the relationship between the phase angle and the height of the dielectric column. Based on (b), (c) is obtained by mapping through HFSS software. The ordinate of (c) is the phase angle (°), and the abscissa is the height of the dielectric column (mm).

[0070] Figure 3 In (d), it is a diagram of the electromagnetic simulation model of the lens 40. Based on the one-to-one correspondence between the phase angle and the height of the dielectric column, (d) is drawn using Solidworks software, that is, the solid form of the lens 40. In the illustrative embodiment, the lens 40 is fabricated using 3D printing technology based on (d). The period of the dielectric column is selected arbitrarily from 0.5 mm to 2 mm on the basis of being less than 1 / 2 wavelength according to the spatial sampling principle. In this article, the period of the dielectric column is the length required for arranging one dielectric column along the x-axis or y-axis direction on the coordinate plane of the lens. In other illustrative embodiments, other processes other than 3D printing technology can also be selected to fabricate the lens 40.

[0071] The obtained lens 40 is used to detect the topological charge number of the vortex electromagnetic wave 30. As Figure 1 shown, during detection, let a vortex electromagnetic wave 30 with an unknown topological charge number m pass through the lens 40 and propagate in free space and then be projected onto the receiving plane 50. Then, judge the topological charge number m of the orbital angular momentum of the vortex electromagnetic wave according to the electric field intensity distribution on the receiving plane and the numerical values of the target electric field intensity at each pixel point on the receiving plane for the vortex electromagnetic waves with different topological charge numbers m.

[0072] Figure 4 , Figure 5 and Figure 6 are respectively the theoretical result diagram, electromagnetic simulation result diagram, and experimental result diagram for detecting the topological charge number of the orbital angular momentum of the vortex electromagnetic wave using the lens in a specific embodiment, where the color bar on the right represents the correspondence between the electric field intensity and the color. The lens is fabricated by the above manufacturing method. During the manufacturing process, the frequency of the vortex electromagnetic wave 30 is 140 GHz, M = 4, and the topological charge number m takes values of 0, 1, 2, 3. The lens has 61×61 dielectric columns, the period of the dielectric column is 1 mm, and the lens uses F4B material. The receiving plane is 40 mm away from the top of the highest dielectric column on the lens. The detection regions 52 corresponding to the 4 topological charge numbers m are as Figure 7 shown, where the detection region 52 on the lower side corresponds to the topological charge number 0, the detection region 52 on the right side corresponds to the topological charge number 1, the detection region 52 on the upper side corresponds to the topological charge number 2, and the detection region 52 on the left side corresponds to the topological charge number 3. Set When, the first numerical value takes 1 and the second numerical value takes 0.

[0073] In Figures 4 to 6 It is known before detection that the topological charge numbers m of the orbital angular momentum of the incident vortex electromagnetic waves corresponding to the upper left figure, upper right figure, lower left figure, and lower right figure are 0, 1, 2, and 3 in sequence. It can be seen from the figure that for each topological charge number m, 4 focused spots (corresponding to the four detection regions 52) are presented on the receiving plane. The value of the topological charge number m judged according to the detection region corresponding to the brightest focused spot is the topological charge number m of the orbital angular momentum of the detected vortex electromagnetic wave, indicating that the detection result has good accuracy. This lens can be used to detect the topological charge numbers of the orbital angular momentum of 4 vortex electromagnetic waves, reducing the cost of detecting the topological charge numbers of the orbital angular momentum of vortex electromagnetic waves.

[0074] For the manufacturing method of this lens, the value of M can be set as needed. When M is greater than 1, the manufactured lens can be used to detect the topological charge numbers m of the orbital angular momentum of several vortex electromagnetic waves, thereby facilitating the reduction of the cost of detecting the topological charge numbers of the orbital angular momentum of vortex electromagnetic waves, which has important significance for the application of vortex electromagnetic waves in multiple fields.

[0075] It can be understood that the lens manufactured by the above method is conducive to reducing the cost of detecting the topological charge numbers of the orbital angular momentum of vortex electromagnetic waves.

[0076] In the schematic embodiment, the period of the dielectric columns of the lens 40 is 0.5 mm to 2 mm, and the number of dielectric columns is 900 to 14884.

[0077] The present invention also provides a use of the above lens 40 for detecting the topological charge number of the orbital angular momentum of the vortex electromagnetic wave 30. In the schematic embodiment, during detection, the vortex electromagnetic wave 30 is allowed to pass through the lens 40 and then projected onto the receiving plane 50 after propagating in free space, and then the topological charge number of the orbital angular momentum of the vortex electromagnetic wave is judged according to the electric field intensity distribution on the receiving plane 50 and the numerical values of the target electric field intensities at each pixel point of the vortex electromagnetic wave 30 with different topological charge numbers on the receiving plane 50. Thereby, it is conducive to reducing the cost of detecting the topological charge numbers of the orbital angular momentum of vortex electromagnetic waves.

[0078] It should be understood that although this specification is described according to each embodiment, not every embodiment only contains an independent technical solution. This narrative manner of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0079] The series of detailed descriptions listed above are only specific descriptions of the feasible embodiments of the present invention, and they are not intended to limit the protection scope of the present invention. Any equivalent implementation schemes or changes made without departing from the technical spirit of the present invention, such as the combination, division, or repetition of features, shall be included within the protection scope of the present invention.

Claims

1. A method for manufacturing a lens, the lens being used to detect the topological charge number of the orbital angular momentum of a vortex electromagnetic wave, the lens having K dielectric columns, where K is a positive integer. During the detection, the vortex electromagnetic wave passes through the lens and propagates in free space and then is projected onto a receiving plane, the receiving plane having N pixel points, where N is a positive integer, and characterized in that, The manufacturing method includes: Setting the values of the topological charge numbers m of M orbital angular momenta to be detected, where M is a positive integer and m is an integer from -10 to 10; Set the target electric field strength at the nth (n = 1, 2, 3... N) pixel point of the receiving plane for vortex electromagnetic waves with different topological charge numbers m value; Calculate the electric field strength of the vortex electromagnetic wave with different topological charge numbers \(m\) projected onto the \(n\)th pixel point of the receiving plane wherein the phase of the complex transmission coefficient of the lens in the \(k\)th (\(k = 1, 2, 3, \cdots, K\)) dielectric column is a variable; Using the following loss function to gradually approximate and optimize the phase distribution of the lens; and Manufacturing a lens using the obtained phase distribution of the lens.

2. The manufacturing method of the lens according to claim 1, characterized in that, Calculating the electric field strength of a vortex electromagnetic wave with a different topological charge number \(m\) projected onto the \(n\)th pixel point of the receiving plane The steps specifically include: Calculate the electric field strength \(E\) of the vortex electromagnetic wave passing through the \(k\)-th dielectric column of the lens, propagating in free space, and then output to the \(n\)-th pixel point of the receiving plane. k , \(E\) k The calculation formula is as follows: E k = w k t k e k Equation (2) Wherein, w k is the transfer function of the free space t k is the complex transmission coefficient of the lens in the k-th dielectric column, e k is the incident electric field strength of the vortex electromagnetic wave incident on the k-th dielectric column; and Calculate the electric field strength at the nth pixel point on the receiving plane after the vortex electromagnetic wave passes through all the dielectric columns of the lens, passes through the lens, and propagates in free space where 3. The manufacturing method of the lens according to claim 2, characterized in that, The said w l The calculation formula is as follows: where d is the distance from the receiving plane to the lens; λ is the wavelength of the vortex electromagnetic wave in vacuum; r is the distance between the k-th dielectric column and the n-th pixel point on the receiving plane, 4. The manufacturing method of the lens according to claim 3, characterized in that, The distance d from the receiving plane to the lens is 20 mm to 60 mm.

5. The manufacturing method of the lens according to claim 2, characterized in that, The said t k has the following calculation formula: where a k is the magnitude of the complex transmission coefficient, with a value of 1; is the phase of the complex transmission coefficient.

6. The manufacturing method of the lens according to claim 2, characterized in that, The said e k The calculation formula is as follows: e k = e jmθ Equation (5) Where: m is the topological charge number of the orbital angular momentum of the vortex electromagnetic wave; θ is the azimuth angle of the vortex electromagnetic wave in the coordinate plane of the lens, θ = arctan(y k / x k ), x k and y k are the coordinates of the k-th dielectric column in the coordinate plane of the lens.

7. The manufacturing method of the lens according to claim 1, characterized in that, Steps for setting the target electric field intensity at the nth pixel point of the receiving plane for vortex electromagnetic waves with different topological charge numbers m, specifically: Select several pixel points concentrated in a region on the receiving plane and set their numerical values to a first numerical value, and set the numerical values of the remaining pixel points to a second numerical value different from the first numerical value, where, for different topological charge numbers the pixel points whose numerical values are set to the first numerical value are different from each other. ​ 8. The manufacturing method of the lens according to claim 1, characterized in that, The step of manufacturing a lens using the obtained phase distribution of the lens specifically includes: Calculating the heights of the respective dielectric columns of the lens according to the phase distribution of the lens and the linear relationship between the phase angle and the height of the dielectric column; and Manufacturing the lens by a 3D printing process according to the calculated heights of the respective dielectric columns of the lens.

9. The manufacturing method of the lens according to claim 1, characterized in that, The frequency range of the vortex electromagnetic wave is 100 GHz to 300 GHz.

10. A lens, characterized in that, It is manufactured by the lens manufacturing method according to any one of claims 1-9.

11. The lens according to claim 10, wherein, The period of the dielectric columns of the lens is 0.5 mm to 2 mm, and the number of dielectric columns is 900 to 14884.

12. Use of the lens according to claim 10 or 11 for detecting the topological charge number of the orbital angular momentum of the vortex electromagnetic wave, characterized in that, During the detection, let the vortex electromagnetic wave pass through the lens and propagate in free space and then be projected onto the receiving plane, and then judge the topological charge number m of the orbital angular momentum of the vortex electromagnetic wave according to the electric field intensity distribution of the receiving plane and the numerical values of the target electric field intensities of the vortex electromagnetic waves with different topological charge numbers m at each pixel point of the receiving plane.

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