Terahertz beam splitter
By using gradient metasurface units in the terahertz beam splitter, the opposite gradient phase mutation is solved, and the problem of complex structure and immutable beam splitter ratio in the prior art is realized, miniaturization of beam splitter and manipulation of beam splitter ratio is realized.
Patent Information
- Application Number
- CN202311381579.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-10-23
- Publication Date
- 2025-04-25
AI Technical Summary
The existing terahertz beam splitter has a complex structure, which cannot achieve variable beam splitting ratio, and is difficult to meet the integration and miniaturization needs of modern optoelectronic systems.
A terahertz beam splitter is designed, using gradient metasurface units, including substrates and cylindrical arrays, and the linear gradient phase mutation of the incident wave is achieved by setting opposite gradient phase mutations in the X direction, thereby achieving beam splitting.
It realizes a terahertz beam splitter with a simple structure and easy to process, and has the ability to split and split ratio control, which promotes device miniaturization and system integration.
Smart Images
Figure CN119890717A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of terahertz and relates to a terahertz beam splitter. Background Art
[0002] Terahertz waves have attracted much attention from researchers at home and abroad for their applications in high-speed communications, radar, and imaging. Among them, the effective regulation of terahertz wave beam splitting is one of the research hotspots in terahertz science and technology. Traditional beam splitters are mainly composed of a combination of multiple anisotropic materials, and have the disadvantages of bulky volume, narrow operating bandwidth, and low efficiency. They mainly use the phase accumulation method to regulate terahertz waves. In order to meet the phase accumulation effect, the design process of traditional wavefront control devices is complex and inflexible, which has become the main obstacle to the integration and miniaturization of modern optoelectronic systems.
[0003] In recent years, phase control and variable splitting ratio within the electromagnetic band have become a research hotspot. There have been some reports on terahertz beam splitters based on metamaterial structures, but most beam splitters have complex structures, are not conducive to processing, and cannot achieve variable splitting ratios.
[0004] Therefore, how to provide a terahertz beam splitter to simplify the structure and achieve a variable splitting ratio has become a technical problem that needs to be urgently solved by those skilled in the art. Summary of the invention
[0005] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a terahertz beam splitter for solving the problem that the beam splitter in the prior art has a complex structure and cannot achieve a variable splitting ratio.
[0006] To achieve the above objectives and other related objectives, the present invention provides a terahertz beam splitter, comprising:
[0007] A gradient metasurface unit, the gradient metasurface unit comprising a substrate and a cylinder array, wherein in the Z direction, the cylinder array is located above the substrate and connected to the substrate; the cylinder array comprises a first array row and a second array row spaced at a preset distance in the Y direction, the first array row comprising a plurality of first dielectric cylinders, the second array row comprising a plurality of second dielectric cylinders, wherein in the X direction, the radius of the first dielectric cylinders increases sequentially, and the radius of the second dielectric cylinders decreases sequentially, so as to achieve a gradient phase mutation opposite to the incident wave.
[0008] Optionally, the increasing gradient of the radius of the first dielectric cylinder is equal to the decreasing gradient of the radius of the second dielectric cylinder.
[0009] Optionally, the body center distances of adjacent first dielectric cylinders are equal, the body center distances of adjacent second dielectric cylinders are equal, and the body center distances of adjacent first dielectric cylinders are equal to the body center distances of adjacent second dielectric cylinders.
[0010] Optionally, in the X-direction projection, the distance between the center of the first dielectric cylinder with the largest radius and the center of the second dielectric cylinder with the smallest radius is equal to zero.
[0011] Optionally, in the X-direction projection, the distance between the body center of the first dielectric cylinder with the largest radius and the body center of the second dielectric cylinder with the smallest radius is not less than the body center distance of adjacent first dielectric cylinders.
[0012] Optionally, the substrate and the cylindrical array are made of polytetrafluoroethylene.
[0013] Optionally, in the Z direction, the thickness of the substrate is in the range of 10-30 μm, and the height of the cylinder array is in the range of 40-60 μm.
[0014] Optionally, the refractive index of the first dielectric cylinder is equal to that of the second dielectric cylinder.
[0015] Optionally, the refractive index of the first dielectric cylinder is unequal to that of the second dielectric cylinder.
[0016] Optionally, there are multiple gradient hypersurface units, and the multiple gradient hypersurface units are arranged in sequence in the X direction.
[0017] As described above, the terahertz beam splitter of the present invention provides a linear gradient phase mutation to the incident wave by setting an opposite gradient phase mutation metasurface, introduces a position-related phase shift, and realizes beam splitting. It has the advantages of simple structure and easy processing, and opens up a new path for the miniaturization of beam splitter devices and system integration. In addition, by changing the equivalent refractive index of the device, the loss degree is changed, and the control of the splitting ratio is realized. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 Shown is a schematic diagram of the three-dimensional structure of the gradient supersurface unit according to the first embodiment of the present invention.
[0019] Figure 2 It is a schematic diagram of a three-dimensional structure in which a single dielectric cylinder is disposed on a substrate unit in the first embodiment of the present invention.
[0020] Figure 3 Shown is a top view of multiple gradient supersurface units arranged along the X direction in Example 1 of the present invention.
[0021] Figure 4It is a schematic diagram showing the phase transmission of the incident wave in the first array row in the first embodiment of the present invention.
[0022] Figure 5 It is a schematic diagram showing the phase transmission of the incident wave in the second array row in the first embodiment of the present invention.
[0023] Figure 6 It is a schematic diagram showing the change of the beam splitting ratio after changing the refractive index of the first dielectric cylinder in the first embodiment of the present invention.
[0024] Figure 7 Shown is a top view of multiple gradient supersurface units arranged along the X direction in the second embodiment of the present invention.
[0025] Component number description
[0026] 10 Gradient metasurface unit
[0027] 100 Substrate
[0028] 1000 Substrate Units
[0029] 110 Cylinder Array
[0030] 1100 Dielectric Cylinder
[0031] 1110 First array row
[0032] 1120 Second array row DETAILED DESCRIPTION
[0033] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.
[0034] See also Figures 1 to 7 It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.
[0035] Embodiment 1
[0036] This embodiment provides a terahertz beam splitter, which includes a gradient metasurface unit. Figure 1, shown as a schematic diagram of the three-dimensional structure of a gradient metasurface unit 10, the gradient metasurface unit 10 includes a substrate 100 and a cylinder array 110, in the Z direction, the cylinder array 110 is located above the substrate 100 and connected to the substrate 100; the cylinder array 110 includes a first array row 1110 and a second array row 1120 spaced a preset distance apart in the Y direction, the first array row 1110 includes a plurality of first dielectric cylinders, the second array row 1120 includes a plurality of second dielectric cylinders, wherein in the X direction, the radius of the first dielectric cylinder increases successively, and the radius of the second dielectric cylinder decreases successively, so as to realize a gradient phase mutation opposite to the incident wave.
[0037] As an example, the increasing gradient of the radius of the first dielectric cylinder in the first array row 1110 is equal to the decreasing gradient of the radius of the second dielectric cylinder in the second array row 1120; for example, the radii of the plurality of first dielectric cylinders are R1, R2, . . . , Rn from left to right in the X direction, where n is an integer greater than 1, and the radii of the plurality of second dielectric cylinders are Rn, . . . , R2, R1 from left to right in the X direction.
[0038] As an example, see Figure 2 , showing a three-dimensional structural schematic diagram of a single dielectric cylinder 1100 arranged on a substrate unit 1000, wherein the width p of the substrate unit 1000 is in the range of 20-40 μm, the thickness t is in the range of 10-30 μm, the height h of the dielectric cylinder 1100 is in the range of 40-60 μm, and the radius thereof increases or decreases in sequence according to demand; specifically, in this embodiment, the width p of the substrate unit 1000 is 30 μm, the thickness t is 20 μm, and the height h of the dielectric cylinder 1100 is 50 μm.
[0039] As an example, in the Y direction projection, the body center positions of multiple first dielectric cylinders correspond to each other, and the body center positions of multiple second dielectric cylinders correspond to each other, wherein the body center distance between adjacent first dielectric cylinders is equal to the width p of the substrate unit 1000, and the body center distance between adjacent second dielectric cylinders is equal to the width p of the substrate unit 1000.
[0040] As an example, in the X-direction projection, the distance between the center point of the first dielectric cylinder with the largest radius and the center point of the second dielectric cylinder with the smallest radius is equal to zero, that is, the first dielectric cylinder with a radius of R1 corresponds to the second dielectric cylinder with a radius of Rn,..., the first dielectric cylinder with a radius of Rn corresponds to the second dielectric cylinder with a radius of R1.
[0041] As an example, the material of the substrate 100 and the cylindrical array 110 is a metamaterial. Specifically, in this embodiment, the material of the substrate 100 and the cylindrical array 110 is polytetrafluoroethylene, which has a high transmittance in the terahertz frequency band.
[0042] As an example, under the action of an external electromagnetic field, the resonance of the gradient metasurface unit 10 can be regarded as a process of forced vibration of a spring oscillator, and the resonance of the gradient metasurface unit 10 can be used to achieve phase control of the metasurface. When in a resonant state, the incident wave exhibits full transmission characteristics within a certain frequency range. Since polytetrafluoroethylene has a high transmittance in the terahertz frequency band, an effective Fabry-Perot resonance can be achieved in the cylindrical array 110, thereby introducing a phase delay to the transmitted wave. By changing the radius of the dielectric cylinder, the phase delay can be adjusted within a range of 2π. Since the radius gradients of the dielectric cylinders of the first array row 1110 and the second array row 1120 are opposite, an opposite phase delay is introduced to achieve phase regulation, and the incident wave can be provided with an opposite linear gradient phase mutation, thereby achieving beam splitting.
[0043] As an example, in practice, a terahertz beam splitter usually includes a plurality of the gradient metasurface units 10, see Figure 3 , showing a top view of a plurality of the gradient metasurface units 10 arranged along the X direction, the terahertz beam splitter has a sub-wavelength period and anomalous refraction, see Figure 4 and Figure 5 , which are respectively shown as a schematic diagram of the phase transmission of the incident wave in the first array row and a schematic diagram of the phase transmission of the incident wave in the second array row. Since the directions of the linear gradient phase mutations of the first array row 1110 and the second array row 1120 are opposite, after the incident wave irradiates the gradient metasurface unit 10, the transmitted wave is divided into two beams.
[0044] As an example, the beam splitting principle of the terahertz beam splitter of the present invention is designed based on the generalized Snell's law, which is realized by phase regulation, and phase regulation is controlled by the resonance of the structure. Therefore, the resonant state can be changed by changing the loss and resonant frequency of the gradient metasurface unit. The loss and resonant frequency of the unit structure are related to the material and its geometric size. The phase can be regulated by designing gradient metasurface units of different materials and sizes to achieve beam splitting and beam splitting ratio regulation. It has great application prospects in terahertz stealth and terahertz imaging. For example, changing the refractive index of the first array row 1110 to change its loss level while keeping the refractive index of the second array row 1120 unchanged can adjust the beam splitting ratio, please refer to Figure 6, it is shown that the imaginary part of the refractive index n of the first array row 1110 increases from 0 to 1.0, and the beam splitting ratio under the x-polarized wave is obtained, T+ represents the transmission intensity of the incident wave in the first array row 1110, and T- represents the transmission intensity of the incident wave in the second array row 1120. When n=0, it means that the refractive index of the first array row 1110 and the second array row 1120 are equal, and the loss degree of the two is equal, and the beam splitting ratio T+:T- is 1:1; the setting rate of the first array row 1110 remains unchanged, and the imaginary part of the refractive index n of the second array row 1120 increases from 0 to 1.0, and the loss degree of the two is inconsistent, resulting in a change in the beam splitting ratio. In the frequency range of 2.5-3.5THz, the beam splitting ratio range under the x-polarized wave is 1:1-1:2, that is, by changing the equivalent refractive index of the device, the control of the beam splitting ratio can be achieved.
[0045] In this embodiment, by setting an opposite gradient phase mutation metasurface, a linear gradient phase mutation is provided to the incident wave, and a position-related phase shift is introduced to achieve beam splitting, which has the advantages of simple structure and easy processing, and opens up a new path for the miniaturization of beam splitters and system integration. In addition, by changing the equivalent refractive index of the device, its loss degree is changed, and the control of the beam splitting ratio can be achieved.
[0046] Embodiment 2
[0047] This embodiment provides a terahertz beam splitter, which is mainly different from the first embodiment in that: in the X-direction projection, the distance between the body center of the first dielectric cylinder with the largest radius and the body center of the second dielectric cylinder with the smallest radius is not less than the body center distance of adjacent first dielectric cylinders.
[0048] As an example, in an ideal state, the first array row 1110 and the second array row 1120 have opposite linear gradient phase mutations, and no phase mutation occurs between the first array row 1110 and the second array row 1120. However, since the radii of the dielectric circumferential bodies of the first array row 1110 and the second array row 1120 are set oppositely, it is inevitable that a phase mutation occurs between the first array row 1110 and the second array row 1120 in the Y direction; Figure 3As shown, in the Y direction, the second dielectric cylinder with the largest radius in the second array row 1120 corresponds to the first dielectric cylinder with the smallest radius in the first array row 1110, and the second dielectric cylinder with the smallest radius in the second array row 1120 corresponds to the first dielectric cylinder with the largest radius in the first array row 1110, so that the first array row 1110 and the second array row 1120 have a large phase gradient in the Y direction, thereby generating a large diffraction in the Y direction, which is not conducive to the beam splitting of the device and the control of the beam splitting ratio. In this embodiment, by setting the distance between the body center of the first dielectric cylinder with the largest radius and the body center of the second dielectric cylinder with the smallest radius to be not less than the body center distance of the adjacent first dielectric cylinders, the purpose is to reduce the phase gradient in the Y direction, thereby reducing the diffraction generated in the Y direction.
[0049] As an example, see Figure 7 , which is a top view of the arrangement of multiple gradient metasurface units along the X direction in this embodiment. The difference from the first embodiment is that: the first array row 1110 is translated in the X direction, so that the second dielectric cylinder with the largest radius in the second array row 1120 does not correspond to the first dielectric cylinder with the smallest radius in the first array row 1110, and the dielectric cylinder with the smallest radius in the second array row 1120 does not correspond to the dielectric cylinder with the largest radius in the first array row 1110, which can reduce the phase gradient in the Y direction, thereby reducing the diffraction generated in the Y direction; for example, when the number of the first dielectric cylinder and the number of the second dielectric cylinder are 6 respectively, the first array row 1110 is translated along -X by a distance of 2p, then in the Y direction, the second dielectric cylinder with a radius of R6 corresponds to the first dielectric cylinder with a radius of R3, and the second dielectric cylinder with a radius of R1 corresponds to the first dielectric cylinder with a radius of R2 in another gradient metasurface unit. Of course, in other examples, the first array row 1110 may be kept stationary and the second array row 1120 may be translated, which also falls within the scope of protection of the present invention.
[0050] In summary, the terahertz beam splitter of the present invention provides a linear gradient phase mutation to the incident wave by setting an opposite gradient phase mutation metasurface, introduces a position-dependent phase shift, and realizes beam splitting. It has the advantages of simple structure and easy processing, and opens up a new path for the miniaturization of beam splitter devices and system integration. In addition, by changing the equivalent refractive index of the device, the loss degree is changed, and the control of the beam splitting ratio is realized. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.
[0051] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.
Claims
1. A terahertz beam splitter, characterized in that: include: A gradient metasurface unit, the gradient metasurface unit comprising a substrate and a cylinder array, wherein in the Z direction, the cylinder array is located above the substrate and connected to the substrate; the cylinder array comprises a first array row and a second array row spaced at a preset distance in the Y direction, the first array row comprising a plurality of first dielectric cylinders, the second array row comprising a plurality of second dielectric cylinders, wherein in the X direction, the radius of the first dielectric cylinders increases sequentially, and the radius of the second dielectric cylinders decreases sequentially, so as to achieve a gradient phase mutation opposite to the incident wave.
2. The terahertz beam splitter according to claim 1, characterized in that: The increasing gradient of the radius of the first dielectric cylinder is equal to the decreasing gradient of the radius of the second dielectric cylinder.
3. The terahertz beam splitter according to claim 2, characterized in that: The body center distances of adjacent first dielectric cylinders are equal, the body center distances of adjacent second dielectric cylinders are equal, and the body center distances of adjacent first dielectric cylinders are equal to the body center distances of adjacent second dielectric cylinders.
4. The terahertz beam splitter according to claim 3, characterized in that: In the X-direction projection, the distance between the center of the first dielectric cylinder with the largest radius and the center of the second dielectric cylinder with the smallest radius is equal to zero.
5. The terahertz beam splitter according to claim 3, characterized in that: In the X-direction projection, the distance between the body center of the first dielectric cylinder with the largest radius and the body center of the second dielectric cylinder with the smallest radius is not less than the body center distance of adjacent first dielectric cylinders.
6. The terahertz beam splitter according to claim 1, characterized in that: The substrate and the cylindrical array are made of polytetrafluoroethylene.
7. The terahertz beam splitter according to claim 1, characterized in that: In the Z direction, the thickness of the substrate ranges from 10 to 30 μm, and the height of the cylinder array ranges from 40 to 60 μm.
8. The terahertz beam splitter according to claim 1, characterized in that: The refractive index of the first dielectric cylinder is equal to that of the second dielectric cylinder.
9. The terahertz beam splitter according to claim 1, characterized in that: The refractive indexes of the first dielectric cylinder and the second dielectric cylinder are not equal.
10. The terahertz beam splitter according to any one of claims 1 to 9, characterized in that: The number of the gradient hypersurface units is multiple, and the multiple gradient hypersurface units are arranged in sequence in the X direction.