Planar orbital angular momentum order conversion structure based on metal plate array

Abstract

The present application relates to the technical field of orbital angular momentum order conversion of planar vortex light, and the existing regulation and control technology generates high-order orbital angular momentum vortex light in the out-of-plane free space, which is difficult to realize the high-order orbital angular momentum order conversion of planar vortex light; the present application provides a planar vortex light orbital angular momentum order conversion structure based on a metal plate array, a vortex light source with low-order orbital angular momentum is arranged at the center, after phase modulation of the metal plate array region, the vortex light beam with high-order orbital angular momentum is directly output in the plane without the help of external optical devices or auxiliary phase elements in the free space. The present application has the advantages of simple structure, flexible regulation and control mode, significantly reduced preparation difficulty and cost of the device, and provides a feasible path for the engineering application of OAM multiplexing communication technology, and can be widely applied to in-plane optical communication systems, effectively improves the system channel capacity and integration, and has important practical application value and popularization prospect.

Description

Technical Field

[0001] This invention relates to the field of in-plane orbital angular momentum order conversion technology for vortex light, and more specifically, to a planar vortex light orbital angular momentum order conversion structure based on a metal plate array. Background Technology

[0002] In recent years, optical vortex and orbital angular momentum technologies have shown great application potential in fields such as optical communication, quantum information, and precision measurement due to their unique phase topology characteristics and multi-dimensional controllability. In optical orbital angular momentum systems, vortex light with high-order orbital angular momentum is often used to improve communication channel capacity. Especially in the field of optical communication, mode division multiplexing using orthogonal vortex light modes corresponding to different orbital angular momentum orders has become a key direction for breaking through the bottleneck of traditional frequency and polarization dimension spectrum resources and improving channel capacity. Among them, in-plane vortex light has advantages in scenarios such as resisting atmospheric turbulence interference and adapting to planar integrated devices due to its coplanar structure of helical phase and propagation direction. Precise control of its orbital angular momentum order has become the core link in expanding the practical application of this technology. However, most existing control schemes generate vortex light with high-order orbital angular momentum in free space outside the plane, making it difficult to achieve efficient and integrated vortex light order conversion in the plane. At present, there is still a lack of integrated structures that can directly complete large-span, quasi-continuous conversion of low-order to high-order orbital angular momentum in the plane. Therefore, designing a simple and easily integrated in-plane vortex light order conversion scheme to achieve efficient conversion of low-order to high-order orbital angular momentum has become a key technical bottleneck for promoting the application of in-plane vortex light in fields such as optical communication. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide an in-plane order conversion structure for vortex optical light based on a metal plate array. The present invention directly outputs a vortex beam with a high-order orbital angular momentum after phase modulation of a vortex light source with a low-order orbital angular momentum via a metal plate array, thereby achieving efficient, wide-span, and integer-order continuous conversion from low-order optical orbital angular momentum to high-order optical orbital angular momentum.

[0004] To achieve the above objectives, the present invention adopts the following solution: A planar vortex beam orbital angular momentum order conversion structure based on a metal plate array includes a high permeability region, a metal plate array region, and a vortex beam order transition region. The high permeability region is located at the center of the metal plate array region, and a low-order orbital angular momentum vortex light source is disposed at the center of the high permeability region. The vortex beam order transition region is located outside the metal plate array region. The low-order orbital angular momentum vortex light source in the high permeability region outputs a high-order orbital angular momentum vortex beam through the planar vortex beam orbital angular momentum order conversion structure. The metal plate array region includes several uniformly distributed spiral plates, with a channel region between adjacent spiral plates. Both the channel region and the vortex optical order jump region are filled with a filling material.

[0005] Furthermore, the permeability of the high permeability region is greater than 1, and the high permeability region has a cylindrical structure.

[0006] Furthermore, the axial extension height of the metal plate array region is consistent with the axial height of the high permeability region.

[0007] Furthermore, all the spiral veneers in the metal plate array region have the same thickness, and the formula for the cross-sectional parameters of the spiral veneers is as follows: Where x and y are the abscissa and ordinate of the rectangular coordinate system, respectively, and s is the polar angle θ used to control the rotation angle of the helix in the polar coordinate system. α It is the constant angle between the tangent to the helix and the polar radius. α The value ranges from 15° to 35°, where R1 is the initial polar radius, i.e., the radius in polar coordinates; the order l of the output vortex beam with higher orbital angular momentum. out = l in + N, where N is the number of spiral plates in the metal plate array region, and N is not less than 30. in The order of the vortex light source is the low-order orbital angular momentum.

[0008] Furthermore, the initial pole diameter R1 of the metal plate array region is the same as the radius of the high permeability region.

[0009] Furthermore, the width of the channel region increases linearly from the inside to the outside with radial distance.

[0010] Furthermore, the wavelength range of the low-order orbital angular momentum vortex light source is 2.7cm to 3.3cm.

[0011] In summary, the present invention has the following beneficial effects: This invention proposes an in-plane order conversion structure for vortex beams based on a metal plate array. It presents an integrated in-plane OAM order conversion scheme without external auxiliary components, enabling efficient, wide-span, and integer-order continuous conversion from low-order vortex beam orbital angular momentum to high-order optical orbital angular momentum. The number of metal plates in the structure can be adjusted according to the actual vortex beam orbital angular momentum order conversion requirements, achieving adjustable OAM order conversion. The structure itself can directly output low-order to high-order vortex beams without complex external control devices or auxiliary phase elements, significantly simplifying the system architecture and improving device integration and practicality.

[0012] Meanwhile, this invention achieves directional phase modulation (OAM) functionality through an equivalent metal plate array. It utilizes the constraint of the metal plates on electromagnetic waves to construct a helical transmission channel, thereby increasing the OAM order through a geometric path. The structure is simple, the control is flexible, and it can be adapted to various filling media with electromagnetic properties similar to air, significantly reducing the fabrication difficulty and cost of the device. This provides a feasible path for the engineering application of OAM multiplexing communication technology. With its simple structure and flexible control method, this invention can be widely applied in in-plane optical communication systems, effectively improving system channel capacity and integration, and possesses significant practical application value and promising prospects for widespread adoption. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of the present invention.

[0014] Figure 2 This is a planar schematic diagram of the present invention.

[0015] Figure 3 Numerical simulation results for converting a vortex light source with an orbital angular momentum of 2 to an orbital angular momentum of 38.

[0016] Figure 4 Numerical simulation results for converting a vortex light source with an orbital angular momentum of 1 to an orbital angular momentum of 37.

[0017] Figure 5 The numerical simulation results show that the vortex light source with an orbital angular momentum of 0 is converted to an orbital angular momentum of 36.

[0018] Figure 6 The numerical simulation results show that the vortex light source with an orbital angular momentum of -1 is converted to an orbital angular momentum of 35.

[0019] Figure 7 Numerical simulation results for converting a vortex light source with an orbital angular momentum of -2 to an orbital angular momentum of 34.

[0020] In the figure, 1 is the high permeability region, 2 is the metal plate array region, 3 is the channel region, and 4 is the vortex light order jump region. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings.

[0022] It should be noted that, for ease of description, the descriptions of direction in the following text are consistent with the directions in the accompanying drawings, but they do not limit the structure of the present invention.

[0023] like Figures 1-7As shown, this invention discloses a planar vortex optical orbital angular momentum order conversion structure based on a metal plate array. It achieves efficient conversion of the orbital angular momentum order of in-plane vortex optical light using only a specifically arranged metal plate array. The structure includes a high permeability region 1, a metal plate array region 2, and a vortex optical order transition region 4. The high permeability region 1 is located at the center of the metal plate array region 2. A low-order orbital angular momentum vortex light source is located at the center of the high permeability region 1. The wavelength range of the low-order orbital angular momentum vortex light source is 2.7 cm to 3.3 cm; in this embodiment, a wavelength of 3 cm and a frequency of 10 GHz are selected. The permeability of the high permeability region 1 is greater than 1, and the high permeability region 1 has a cylindrical structure. The vortex optical order transition region 4 is located outside the metal plate array region 2. The low-order orbital angular momentum vortex light source in the high permeability region 1 outputs a high-order orbital angular momentum vortex beam through a planar vortex beam orbital angular momentum order conversion structure. The metal plate array region 2 includes several uniformly distributed spiral plates, with a channel region 3 between adjacent spiral plates. Both the channel region 3 and the vortex beam order transition region 4 are filled with material. The width of the channel region 3 increases linearly from the inside to the outside with the radial distance. The width of the same channel is determined by the thickness of the metal plate, the angle between adjacent metal plates, and its radial position, increasing from the inside to the outside with the radial distance. The axial extension height of the metal plate array region 2 is consistent with the axial height of the high permeability region 1. All spiral plates in the metal plate array region 2 have the same thickness, and the parameter formulas for the cross-section of the spiral plates are as follows: Where x and y are the abscissa and ordinate of the rectangular coordinate system, respectively, and s is the polar angle θ used to control the rotation angle of the helix in the polar coordinate system. α It is the constant angle between the tangent to the helix and the polar radius. α The value ranges from 15° to 35°, where R1 is the initial polar radius, i.e., the radius in polar coordinates. The initial polar radius R1 of the metal plate array region 2 is the same as the radius of the high permeability region 1; the order l of the output vortex beam with higher orbital angular momentum. out = l in + N, where N is the number of spiral plates in region 2 of the metal plate array, and N is not less than 30. in The order of the vortex source with low-order orbital angular momentum; by changing the parameters s and α The shape of the spiral single plate can be adjusted. The high permeability region 1, the metal plate array region 2, and the channel region 3 can be adjusted according to actual usage requirements. The outer radius of the metal plate array region 2 is related to the spiral single plate. When the shape of the spiral single plate changes due to parameter changes or changes in the number of spiral single plates, the outer radius of the metal plate array region 2 changes accordingly. The spiral single plate can be made of metal materials such as copper, aluminum, or alloys. The included angle between adjacent spiral single plate structures is equal, forming a channel with uniformly varying thickness.

[0024] Example In this embodiment, the electromagnetic wave is a TM polarized wave with a working wavelength of 3 cm and a corresponding frequency of 10 GHz. The high permeability region 1 is cylindrical, the metal plate array region 2 consists of 36 spiral metal plates, and the channel region 3 and the vortex optical order transition region 4 are filled with materials such as air, polytetrafluoroethylene (PTFE), and glass. Specific structural properties are as follows... Figure 1 and Figure 2 As shown. In this embodiment, the cross-sectional dimensions of each region are as follows: the radius of the high permeability region 1 is 7cm, the radius of the metal plate array region 2 is 20cm, and a circle with a radius of 7cm is cut out at the center to form the region of the high permeability region 1.

[0025] The permeability of high-permeability region 1 is greater than 1. The metal plate array region 2 is made of copper, aluminum, alloys, etc., and exhibits near total internal reflection of electromagnetic waves, with a skin depth of nearly 0. The channel region 3 and the vortex optical order transition region 4 are filled with materials such as air, polytetrafluoroethylene (PTFE), and glass. The technical effects of this invention can be achieved whether the filling materials of channel region 3 and vortex optical order transition region 4 are the same or different. The filling materials can be adjusted according to the actual scenario; air, PTFE, glass, etc., can be used as the filling materials for channel region 3 and vortex optical order transition region 4.

[0026] When a vortex light source with an orbital angular momentum of 2 is placed at the center of the high permeability region 1, the in-plane order conversion structure of the vortex light of the present invention outputs a vortex light with an orbital angular momentum order of 38 in the vortex light order jump region. Figure 3 The numerical simulation results show that the vortex light source with an orbital angular momentum of 2 in this embodiment is converted to an orbital angular momentum of 38.

[0027] When a vortex light source with an orbital angular momentum of 1 is placed at the center of the high permeability region 1, the in-plane order conversion structure of the vortex light of the present invention outputs a vortex light with an orbital angular momentum order of 37 in the vortex light order jump region. Figure 4 The numerical simulation results show that the vortex light source with an orbital angular momentum of 1 in this embodiment is converted to an orbital angular momentum of 37.

[0028] When a vortex light source with zero orbital angular momentum is placed at the center of the high permeability region 1, the in-plane order conversion structure of the vortex light of the present invention outputs a vortex light with an orbital angular momentum order of 36 in the vortex light order jump region. Figure 5 The numerical simulation results show that the vortex light source with an orbital angular momentum of 0 in this embodiment is converted to an orbital angular momentum of 36.

[0029] When a vortex light source with an orbital angular momentum of -1 is placed at the center of the high permeability region 1, the in-plane order conversion structure of the vortex light of the present invention outputs a vortex light with an orbital angular momentum order of 35 in the vortex light order jump region. Figure 6 The numerical simulation results are used to convert the vortex light source with an orbital angular momentum of -1 to an orbital angular momentum of 35 in this embodiment.

[0030] When a vortex light source with an orbital angular momentum of -2 is placed at the center of the high permeability region 1, the in-plane order conversion structure of the vortex light of the present invention outputs a vortex light with an orbital angular momentum order of 34 in the vortex light order jump region. Figure 7 The numerical simulation results show that the vortex light source with an orbital angular momentum of -2 in this embodiment is converted to an orbital angular momentum of 34.

[0031] The structure of this invention features a vortex light source with low-order orbital angular momentum at its center. After phase modulation by a metal plate array, a vortex beam with high-order orbital angular momentum can be directly output without complex external control devices or auxiliary phase elements. This invention offers a simple structure, flexible control methods, and improved communication channel capacity through orbital angular momentum multiplexing technology.

[0032] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A planar vortex optical orbital angular momentum order conversion structure based on a metal plate array, characterized in that, It includes a high permeability region (1), a metal plate array region (2), and a vortex light order jump region (4). The high permeability region (1) is located at the center of the metal plate array region (2), and a low-order orbital angular momentum vortex light source is provided at the center of the high permeability region (1). The vortex light order jump region (4) is located outside the metal plate array region (2). The low-order orbital angular momentum vortex light source of the high permeability region (1) outputs a high-order orbital angular momentum vortex beam through a planar vortex light orbital angular momentum order conversion structure. The metal plate array region (2) includes several uniformly distributed spiral plates, and the area between adjacent spiral plates is a channel region (3). Both the channel region (3) and the vortex light order jump region (4) are filled with filler.

2. The planar vortex optical orbital angular momentum order conversion structure based on a metal plate array according to claim 1, characterized in that, The permeability of the high permeability region (1) is greater than 1, and the high permeability region (1) has a cylindrical structure.

3. The planar vortex optical orbital angular momentum order conversion structure based on a metal plate array according to claim 1, characterized in that, The axial extension height of the metal plate array region (2) is consistent with the axial height of the high permeability region (1).

4. The planar vortex optical orbital angular momentum order conversion structure based on a metal plate array according to claim 3, characterized in that, All the spiral plates in the metal plate array region (2) have the same thickness, and the parameter formulas for the cross-section of the spiral plates are as follows: Where x and y are the abscissa and ordinate of the rectangular coordinate system, respectively, and s is the polar angle θ used to control the rotation angle of the helix in the polar coordinate system. α It is the constant angle between the tangent to the helix and the polar radius. α The value ranges from 15° to 35°, where R1 is the initial polar radius, i.e., the radius in polar coordinates; the order l of the output vortex beam with higher orbital angular momentum. out = l in + N, where N is the number of spiral plates in the metal plate array region (2), and N is not less than 30. in The order of the vortex light source is the low-order orbital angular momentum.

5. The planar vortex optical orbital angular momentum order conversion structure based on a metal plate array according to claim 4, characterized in that, The initial polar radius R1 of the metal plate array region (2) is the same as the radius of the high permeability region (1).

6. The planar vortex optical orbital angular momentum order conversion structure based on a metal plate array according to claim 1, characterized in that, The width of the channel region (3) increases linearly from the inside to the outside with radial distance.

7. The planar vortex optical orbital angular momentum order conversion structure based on a metal plate array according to claim 1, characterized in that, The wavelength range of the vortex light source with low-order orbital angular momentum is 2.7cm to 3.3cm.

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