Metasurface-based spatial phased array and control method

Abstract

This invention discloses a space phased array based on metasurfaces and its control method. The space phased array includes a time-domain reflectometric metasurface array and an optical fiber control unit. The time-domain reflectometric metasurface array is composed of metasurface elements arranged continuously in an array configuration. The optical fiber control unit contains optical paths with the same number of metasurface elements as the time-domain reflectometric metasurface array. All optical paths are connected one-to-one to the photodiode input terminals on the back of different metasurface elements. Each optical path can independently control the light intensity of the input photodiode. By controlling the light intensity of each optical path, the output voltage of the photodiodes on different metasurface elements in the time-domain reflectometric metasurface array and the bias voltage across the varactor diodes are changed, causing different metasurface elements to generate corresponding microwave reflection harmonic distributions, thereby directly mapping the optical signal onto the microwave signal. This invention can achieve control over the reflection of spatial electromagnetic waves in any direction.

Description

Technical Field

[0001] This invention relates to a spatial phased array based on metasurfaces, belonging to the technical field of optical domain and radio frequency conversion to realize optical-controlled radio frequency communication. Background Technology

[0002] Metasurfaces, composed of periodic or quasi-periodic subwavelength metamaterial units, possess tunable characteristics such as microwave phase. Dynamic metasurfaces can be used to construct electromagnetic devices with reconfigurable or programmable functions, such as optical cloaking, and to realize advanced multifunctional systems. To design active metasurfaces for dynamically controlled electromagnetic waves, various control mechanisms have been explored, including electrical, temperature, and optical control methods. Among these, electrical modules are most commonly used for electronic control. Adjustable modules, such as diodes, transformers, and bias lines, must be physically connected to the power supplier via wires, causing electromagnetic interference and making integration extremely difficult. This problem becomes even more challenging when more advanced and multi-tasking devices and unit systems require more elements. Compared to wired electrical methods, optical control avoids electromagnetic interference problems; however, traditional optical illumination control is costly, complex to manufacture, and difficult to control. Therefore, there is an urgent need for a low-cost metasurface resistant to electromagnetic interference. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of the existing technology and propose a space phased array based on metasurfaces and its control method. This invention achieves phase modulation in the microwave band using only a varactor diode and a photodiode, demonstrating exceptional potential in realizing communication systems that are resistant to electromagnetic interference, low-cost, low-complexity, and highly integrated.

[0004] To achieve the above-mentioned objectives, the technical solution proposed by this invention is as follows:

[0005] In a first aspect, the present invention provides a space phased array based on metasurfaces, which includes a time-domain reflectometric metasurface array and an optical fiber control unit; the time-domain reflectometric metasurface array is formed by continuously arranging metasurface units in an array configuration;

[0006] The metasurface unit includes a photodiode, two inductors, a varactor diode, and a multilayer composite structure. The multilayer composite structure, from top to bottom, consists of a surface metal pattern layer, a first dielectric layer, a metal ground layer, a second dielectric layer, and a back metal pattern layer. The surface metal pattern layer comprises two sets of patterned metal sheets arranged in a mirror-symmetrical manner. Each set of patterned metal sheets includes a hexagonal metal sheet and a first connecting metal sheet, which are connected by an inductor. The hexagonal metal sheet is composed of isosceles trapezoidal metal sheets and rectangular metal sheets. The bottom edge of the sheet coincides with the long edge of the rectangular metal sheet and is continuously spliced ​​together; the two hexagonal metal sheets in the two sets of patterned metal sheets are spaced apart, and their trapezoidal top edges are arranged in parallel and connected by a varactor diode; the back metal pattern layer includes two second connecting metal sheets, which are respectively connected to the two voltage output terminals of the photodiode; the two first connecting metal sheets in the surface metal pattern layer and the two second connecting metal sheets in the back metal pattern layer are respectively connected by a conductor that penetrates the multilayer composite structure, and the conductor remains insulated from the metal ground layer when it passes through the metal ground layer;

[0007] The fiber optic control unit contains the same number of optical paths as the metasurface units in the time-domain reflectometry metasurface array. All optical paths are connected one-to-one to the photodiode input terminals on the back of different metasurface units. Each optical path can independently control the light intensity of the input photodiode. By controlling the light intensity of each optical path, the output voltage of the photodiode on different metasurface units in the time-domain reflectometry metasurface array and the bias voltage across the varactor diode are changed, so that different metasurface units generate corresponding microwave reflection harmonic distributions, thereby directly mapping the optical signal onto the microwave signal.

[0008] As a preferred embodiment of the first aspect, in the metasurface unit, the first connecting metal sheet is a rectangular metal sheet, the second connecting metal sheet is an L-shaped metal sheet, and the two are connected by a metal pillar; the metal pillar is installed in a through hole penetrating the multi-layer composite structure.

[0009] As a preferred embodiment of the first aspect, the metal column is insulated from the metal ground layer at the location where it passes through the metal ground layer by wrapping a circular dielectric layer around the metal column.

[0010] As a preferred embodiment of the first aspect, in the time-domain reflective metasurface array, the metasurface units are periodically and continuously arranged in an n*n rectangular array form, where n is an integer not less than 2.

[0011] As a preferred embodiment of the first aspect above, the fiber optic control unit includes a laser, an optical fiber, a beam splitter, and an attenuator. The light source generated by the laser is input into the optical fiber, which is then split into multiple optical signals by a multi-stage beam splitter. Each optical signal is connected to a photodiode on the back of a metasurface unit after passing through an independent attenuator. The fiber optic control unit controls the light intensity of each optical signal input to the photodiode by controlling the distribution ratio of each beam splitter and the attenuation of each attenuator.

[0012] As a preferred embodiment of the first aspect, in the optical fiber control unit, the optical fiber is split into two optical paths each time it passes through a beam splitter, and the total number of optical path signals ultimately formed by the multi-stage beam splitters is the same as the number of metasurface units in the domain reflective metasurface array.

[0013] As a preferred embodiment of the first aspect, the surface metal pattern layer, the metal ground layer, and the back metal pattern layer are all made of copper.

[0014] As a preferred embodiment of the first aspect, the first dielectric layer, the second dielectric layer, and the annular dielectric layer are all made of polytetrafluoroethylene glass cloth copper-clad foil F4B, with a dielectric constant of 2.65 and a loss tangent of 0.001.

[0015] As a preferred embodiment of the first aspect, the metasurface unit is a square plane with a side length of 16 mm; the first dielectric layer, the second dielectric layer, and the metal ground layer are also squares with a side length of 16 mm; among the hexagonal metal sheets, the isosceles trapezoidal metal sheet has a top side length of 4 mm, a bottom side length of 12 mm, a trapezoidal height of 3.6 mm, and a rectangular metal sheet has a length of 12 mm and a width of 2 mm.

[0016] Secondly, the present invention provides a method for controlling the reflection direction of a spatial phased array as described in any of the embodiments of the first aspect above. Based on the target reflection direction of the metasurface reflection beam, by controlling the distribution ratio of each beam splitter and the attenuation value of each attenuator in the fiber optic control unit, the input light intensity of the photodiode, the output voltage of the photodiode, the bias voltage across the varactor diode, and the reflection phase of the metasurface unit on the incident microwave are correlatedly changed, so that the reflection phase of all metasurface units on the time-domain reflective metasurface array presents a distribution state that decreases equally toward the target reflection direction, thereby reflecting the incident microwave along the target reflection direction.

[0017] Compared with the prior art, the beneficial effects of this invention are as follows:

[0018] In wireless communication, signals need to be loaded onto orthogonally polarized electromagnetic waves for transmission in different directions. Traditional isotropic metasurfaces struggle to control different beams. Similarly, in electromagnetic imaging, obtaining a holographic image containing orthogonally polarized states is difficult because traditional isotropic metasurfaces cannot independently control the two polarization states, hindering the achievement of holographic imaging with different polarization states. Currently, devices capable of independently controlling the orthogonal polarization components of electromagnetic waves are indispensable in both communication and imaging. Tunable microwave metasurfaces primarily utilize electronic control technology, inevitably leading to electromagnetic interference (EMI) issues, resulting in poor system EMI compatibility and integration difficulties. While current optically controlled metasurfaces mostly employ non-contact projection, this method avoids EMI, but the incident light intensity cannot be precisely controlled, manufacturing is complex, and it is susceptible to environmental influences.

[0019] This invention provides a metasurface-based spatial phased array that connects a laser source to a photodiode on the metasurface via an optical fiber array to achieve control over the metasurface. When the input light is distributed with a higher incident light intensity, the photodiode generates a higher bias voltage, which is added to the varactor diode through an inductor via a via, causing a corresponding change in the varactor diode's equivalent capacitance. By altering the equivalent RCL parameter of the metasurface, the phase of the reflected wave is changed. The phase angle of the reflected wave is varied in a certain direction by the metasurface array elements, causing the reflected wave to be emitted in a specific direction. The inductor on the front side of the metasurface can isolate high-frequency waves, thus avoiding the impact of changes in the equivalent RCL parameter of the photodiode on the overall metasurface performance. Compared to previously mentioned control methods, the laser source input to the photodiode via an optical fiber array effectively avoids electromagnetic interference between wires, allows for flexible and rapid adjustment of the metasurface by varying the light intensity of each element in the optical fiber array, and features a simple manufacturing process, lower cost, and facilitates the integration of adjustable superreflective surfaces into the system.

[0020] The spatial phased array based on metasurface provided by this invention enables optically controlled microwave metasurfaces to exhibit excellent electromagnetic compatibility characteristics, showing extraordinary potential in realizing hybrid communication systems with high integration, low complexity, and simple fabrication. This is crucial for the integrated development of radio frequency devices and systems. Attached Figure Description

[0021] Figure 1 This is a block diagram of the spatial phased array structure based on metasurface of the present invention;

[0022] Figure 2 This is a schematic diagram of the cross-sectional structure of a single metasurface unit;

[0023] Figure 3 This is a schematic diagram of the surface metal pattern layer structure of the metasurface array of the present invention;

[0024] Figure 4 It is an enlarged view of the surface metal pattern;

[0025] Figure 5 This is a schematic diagram of the back metal pattern layer structure of the metasurface array of the present invention;

[0026] Figure 6 These are test curves showing the reflection phase of a metasurface-based spatial phased array structure under different frequencies of x-polarized wave incident, as a function of the varactor diode capacitance.

[0027] Figure 7 This invention relates to the effect of capacitance variation on the phase of reflected light at the same frequency when irradiating a metasurface-based spatial phased array, as described in an embodiment of the invention.

[0028] The figures are labeled as follows: 1. Laser; 2. Optical fiber; 3. Beam splitter; 4. Attenuator; 5. Photodiode array; 6. Time-domain reflectometry metasurface array; 7. Back metal pattern layer; 8. Surface metal pattern layer; 9. Photodiode; 10. Varactor diode; 11. Inductor; 12. Hexagonal metal sheet; 13. First connecting metal sheet; 14. Through-hole; 15. First dielectric layer; 16. Metal ground layer; 17. Second dielectric layer. Detailed Implementation

[0029] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. Technical features in the various embodiments of the present invention can be combined accordingly without mutual conflict.

[0030] In the description of this invention, it should be understood that when an element is considered to be "connected" to another element, it can be a direct connection to the other element or an indirect connection, i.e., there is an intermediate element. Conversely, when an element is said to be "directly" connected to another element, there is no intermediate element.

[0031] In the description of this invention, it should be understood that the terms "first" and "second" are used only for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" and "second" may explicitly or implicitly include at least one of those features.

[0032] The invention will now be further explained with reference to the accompanying drawings.

[0033] This invention designs a spatial phased array based on metasurfaces, comprising a time-domain reflectometry (TD-RESP) metasurface array and an optical fiber control unit. First, a broadband TRP metasurface array is designed. Each unit has a special metallic pattern, with its scanning size optimized to achieve the best effect, enabling it to generate a reflection phase difference of approximately 360° within a wide microwave frequency band. The front metallic pattern of the unit integrates two inductors and a varactor diode, while the back pattern integrates a photodiode (PD). The reflection phase is changed by controlling the bias voltage across the varactor diode by altering the incident light intensity of the PD. n×n metasurface units are arrayed to form the TRP metasurface array. Each metasurface unit in this array has the same size and is controlled using the same control waveform. The optical fiber control unit contains an optical control array connected to the PD on the back of the TRP metasurface array. Each unit of the two arrays is connected. The PD, excited by incident light, provides a control voltage to the varactor diode.

[0034] Using the aforementioned metasurface-based spatial phased array, beam phase control can be achieved. When the intensity of the incident light varies arithmetically with equal phase angles in each column or row, the metasurface platform generates a phase-modulated reflected harmonic distribution under microwave incidence, allowing for precise control of the reflected wave propagation direction and beam propagation direction. Furthermore, the control method of inputting the laser source to the PD via an optical fiber array effectively avoids electromagnetic interference between wires, and the metasurface can be flexibly and rapidly adjusted by varying the intensity of each unit in the optical fiber array. Moreover, the fabrication process is simple, the cost is low, and it facilitates the integration of tunable superreflective surfaces into the system.

[0035] The following is a detailed description of specific embodiments of the metasurface-based spatial phased array design described above.

[0036] like Figure 1 As shown, in a preferred embodiment of the present invention, a space phased array based on metasurfaces is provided, comprising a time-domain reflectometry metasurface array 6 and an optical fiber control unit, wherein the time-domain reflectometry metasurface array 6 is formed by continuously arranging metasurface units in an array configuration. In this embodiment, the metasurface units are periodically and continuously arranged in an n*n rectangular array configuration, where n is an integer not less than 2.

[0037] The fiber optic control unit comprises a laser 1, an optical fiber 2, a beam splitter 3, and an attenuator 4. The light source generated by the laser 1 is input into the optical fiber 2, which is then split into multiple optical signals by a multi-stage beam splitter 3. Each optical signal passes through an independent attenuator 4 and is connected to a photodiode 9 on the back of a metasurface unit. All the photodiodes 9 in the time-domain reflectometry metasurface array 6 form a photodiode array 5. The fiber optic control unit controls the beam splitter 3's distribution ratio and the attenuation of each attenuator 4, thereby controlling the light intensity of each optical signal input to the photodiode 9.

[0038] It should be noted that in the aforementioned fiber optic control unit, fiber 2 is split into two optical paths each time it passes through a beam splitter 3. To ensure that each metasurface unit in the time-domain reflectometry metasurface array 6 can independently input a controllable optical signal, the total number of optical signals formed by the multi-stage beam splitter 3 must be the same as the number of metasurface units in the time-domain reflectometry metasurface array 6. That is, if the number of metasurface units in the time-domain reflectometry metasurface array 6 is n*n, then the signal from the light source, after being split by the x-stage multi-stage beam splitter 3, also needs to be divided into n*n optical signals. Then, each optical signal is connected to the photodiode 5 on the back of the metasurface 6 via an attenuator 4. The intensity of the light received by the photodiode is controlled by adjusting the beam splitter distribution ratio and the attenuator attenuation.

[0039] The metasurface unit of this invention comprises a photodiode 9, two inductors 11, a varactor diode 10, and a multilayer composite structure. Among them, as... Figure 2 As shown, the multilayer composite structure, from top to bottom, consists of a surface metal pattern layer 8, a first dielectric layer 15, a metal ground layer 16, a second dielectric layer 17, and a back metal pattern layer 7. The back metal pattern layer 7 on the back of the metasurface unit has a different pattern than the surface metal pattern layer 8 on the front. A photodiode 9 is located on the back of the metasurface to receive the optical array signal. When the incident light power increases, the photodiode generates a larger bias voltage, thus reducing the equivalent capacitance of the varactor diode and altering the phase of the reflected signal from the metasurface. By independently controlling the attenuator 4, the reflection phase of the metasurface unit can be changed. By controlling the phase of the array unit in a certain direction with equal arithmetic changes, the direction of the reflected wave can be arbitrarily controlled.

[0040] like Figure 3 and Figure 4As shown, in each metasurface unit, the surface metal pattern layer 8 comprises two sets of patterned metal sheets arranged in a mirror-symmetric manner. Each set of patterned metal sheets includes a hexagonal metal sheet 12 and a first connecting metal sheet 13, with the two sets of patterned metal sheets symmetrically arranged on both sides of the mirror-symmetry plane. On each side, the hexagonal metal sheet 12 is connected to the first connecting metal sheet 13 on the same side via an inductor 11. The hexagonal metal sheet 12 is composed of an isosceles trapezoidal metal sheet and a rectangular metal sheet, with the base of the isosceles trapezoidal metal sheet exactly overlapping and continuously joined with the long side of the rectangular metal sheet. The trapezoidal apex edges of the two hexagonal metal sheets 12 in the two sets of patterned metal sheets are arranged opposite each other, with a certain interval between the two hexagonal metal sheets 12, and the trapezoidal apex edges of the two hexagonal metal sheets 12 are parallel to each other and connected via a varactor diode 10.

[0041] It should be noted that the hexagonal metal sheet 12 is divided into isosceles trapezoidal metal sheet and rectangular metal sheet here only for the convenience of describing its shape, but does not mean that two separate metal sheets need to be processed first and then spliced ​​together. In actual application, it can be processed directly as a whole.

[0042] In addition, such as Figure 5 As shown, in each metasurface unit, the back metal pattern layer 7 includes two second connecting metal sheets, which are respectively connected to the two voltage output terminals of the photodiode 9; the two first connecting metal sheets 13 in the surface metal pattern layer 8 and the two second connecting metal sheets in the back metal pattern layer 7 are respectively connected by a conductor penetrating the multilayer composite structure, and the conductor remains insulated from the metal ground layer 16 when it passes through the metal ground layer 16. The function of the metal ground layer 16 is to isolate the front and back sides of the metasurface unit and prevent interference between the two sides.

[0043] The shapes of the first connecting metal sheet 13 and the second connecting metal sheet are not limited, but their main function is to connect the hexagonal metal sheet 12 to the back metal pattern layer 7. The specific form of the conductor is not limited, as long as it enables conduction between the metal patterns on both sides. In this embodiment, the first connecting metal sheet 13 is a rectangular metal sheet, the second connecting metal sheet is an L-shaped metal sheet, and the conductor is a metal pillar. The rectangular and L-shaped metal sheets on the same side are connected by a metal pillar. A through-hole 14 needs to be opened in the multilayer composite structure, and the metal pillar is installed in the through-hole 14 that penetrates the multilayer composite structure. To ensure insulation between the metal pillar and the metal ground layer 16, the metal ground layer 16 has a larger opening at the location of the through-hole 14. An annular ring made of dielectric material is embedded in this opening. The inner diameter of the annular ring is the same as the diameter of the through-hole 14, and the outer diameter is the same as the diameter of the opening. Thus, at the location where the metal pillar passes through the metal ground layer 16, insulation is achieved between the metal pillar and the metal ground layer 16 through the annular dielectric layer surrounding the metal pillar.

[0044] The size parameters and selection of each component in the above metasurface unit can be optimized according to the actual situation, and the best parameters should be selected based on the final performance.

[0045] Regarding the materials, the surface metal pattern layer 8, the metal ground layer 16, and the back metal pattern layer 7 are all made of copper. The first dielectric layer 15, the second dielectric layer 17, and the annular dielectric layer are all made of polytetrafluoroethylene glass cloth copper-clad foil F4B, with a dielectric constant of 2.65 and a loss tangent of 0.001.

[0046] Regarding dimensional parameters, the metasurface unit is a square plane with a side length of 16 mm. The first dielectric layer 15 and the second dielectric layer 17 are also squares with a side length of 16 mm, and the metal ground layer 16 also uses a square copper sheet with a side length of 16 mm. In the surface metal pattern layer 8, the isosceles trapezoidal metal sheet in the hexagonal metal sheet 12 has a top side length of 4 mm, a bottom side length of 12 mm, and a trapezoidal height of 3.6 mm, while the rectangular metal sheet has a length of 12 mm and a width of 2 mm; the first connecting metal sheet 13 has a length of 1.5 mm and a width of 0.5 mm; the top side spacing between the two hexagonal metal sheets 12 is 0.8 mm. In the back metal pattern layer 7, the L-shaped metal sheet has a width of 5 mm, and its length is sufficient to connect the metal pillar and the photodiode 9. The thickness of the surface metal pattern layer 8, the metal ground layer 16, and the back metal pattern layer 7 is 0.018 mm. The first dielectric layer 15 has a thickness of 3 mm, the second dielectric layer 17 has a thickness of 0.2 mm, and the radius of the via 14 is 0.25 mm. The outer diameter of the annular dielectric layer surrounding the metal pillar is 0.5 mm, and the inner diameter is 0.25 mm. Inductor 11 uses two 8 nH inductors, and varactor diode 10 uses "MAVR-000120-14110P", whose capacitance can vary from 1.15 pF to 0.14 pF. The metasurface unit can achieve high reflectivity and large phase difference in the frequency range of 5.5 to 7.5 GHz. An n×n array is formed using this metasurface unit.

[0047] Since the aforementioned fiber optic control unit contains the same number of optical paths as the metasurface units in the time-domain reflectotropic metasurface array 6, all optical paths are connected one-to-one to the input terminals of the photodiodes 9 on the back of different metasurface units. Because each optical path can independently control the light intensity of the input photodiode 9, the output voltage of the photodiodes 9 on different metasurface units in the time-domain reflectotropic metasurface array 6 is changed by controlling the light intensity of each optical path. Furthermore, as the output voltage of the photodiodes 9 changes, the bias voltage across the varactor diode 10 can be further changed, causing different metasurface units to generate corresponding microwave reflection harmonic distributions, thereby directly mapping the changes in the optical signal onto the microwave signal.

[0048] Therefore, in the aforementioned time-domain reflective metasurface array, each metasurface unit is independent of its surrounding metasurface units, thus achieving individual tunability. The reflection phase of each unit in the array changes with the intensity of the light entering through the back PD pigtail, thereby achieving reflection phase control. The photodiode generates a corresponding voltage-controlled varactor diode by receiving incident light of different intensities through the optical fiber, producing a certain microwave reflection harmonic distribution, thereby realizing dynamic adjustment of the phase signal of the incident wave.

[0049] The reflection direction control method based on the above-mentioned spatial phased array is as follows: According to the target reflection direction of the metasurface reflection beam, by controlling the distribution ratio of each beam splitter 3 and the attenuation value of each attenuator 4 in the fiber optic control unit, the input light intensity of photodiode 9, the output voltage of photodiode 9, the bias voltage across varactor diode 10, and the reflection phase of the incident microwave by the metasurface unit are correlatedly changed. This makes the reflection phase of all metasurface units on the time-domain reflective metasurface array 6 present a distribution state that decreases arithmetically towards the target reflection direction, thereby reflecting the incident microwave along the target reflection direction. For example, if it is necessary to control the target reflection direction of the metasurface reflection beam to the left, the input light intensity of each photodiode 9 in the photodiode array 5 can be controlled to make the reflection phase of all metasurface units on the time-domain reflective metasurface array 6 present a distribution state that decreases arithmetically from right to left. At this time, the incident microwave will be reflected to the left.

[0050] When the input light is distributed to each unit's PD with different light intensities according to the design, the metasurface unit can produce different phase changes at a certain angle. The arithmetic phase angle changes of the row and column units in the array can map the reflected waveform to the desired direction, thereby realizing the control of the direction of space microwave propagation.

[0051] Figure 6 The figure shows the characteristic curves of the reflection phase and assigned values ​​of the metasurface S-parameters of the spatial phased array based on the metasurface under the incident x-polarized waves of different frequencies. As can be seen from the figure, the reflection phase of the metasurface changes accordingly with the change of the surface equivalent capacitance value in the range of 5.5 GHz to 7.5 GHz, and the amplitude attenuation is small.

[0052] Figure 7This figure shows the test curves of the reflection phase of the metasurface-based spatial phased array under different frequencies of x-polarized wave incident light, as a function of the varactor diode capacitance. Clearly, as the capacitance gradually increases from 0.15 pF to 0.6 pF, the reflection phase changes accordingly from -180° to approximately 180°, providing a phase shift of approximately 360° across all test frequencies. The test curves at the six frequency points marked in the figure are well distinguishable and conform to the RCL characteristics of the metasurface array. The experimental results verify that the realized metasurface-based spatial phased array can achieve a large phase adjustment range over a wide frequency band.

[0053] In this invention, electromagnetic waves are incident on the metasurface and reflected, and the phase of the reflection can be controlled by the metasurface. By explicitly controlling the direction of the reflected beam from the metasurface, setting the distribution ratio of each beam splitter and the attenuation value of each attenuator, the metasurface units decrease arithmetically in the direction of reflection, thereby achieving control over the reflection of spatial electromagnetic waves in any direction, and reducing the gradient related to the tilt direction of the reflection.

[0054] The attenuator 4 and beam splitter 3 mentioned above can be controlled by an FPGA. By controlling the attenuator through the FPGA, the output light intensity of each optical path in the optical array can be affected, effectively controlling the state of the metasurface PD. The reflected phase of the incident microwave can be changed in real time, and the deflection of spatial electromagnetic waves in any direction can be achieved by controlling each unit of the array. Since fiber optic access control is used, the electromagnetic interference caused by the equivalent inductance and capacitance of wires in the high-frequency band can be avoided, allowing the metasurface to achieve a higher degree of integration.

[0055] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all technical solutions obtained through equivalent substitution or transformation fall within the protection scope of the present invention.

Claims

1. A spatial phased array based on a metasurface, characterized in that, It includes a time-domain reflective metasurface array (6) and an optical fiber control unit; the time-domain reflective metasurface array (6) is composed of metasurface units arranged continuously in an array form; The metasurface unit includes a photodiode (9), two inductors (11), a varactor diode (10), and a multilayer composite structure. The multilayer composite structure consists of a surface metal pattern layer (8), a first dielectric layer (15), a metal ground layer (16), a second dielectric layer (17), and a back metal pattern layer (7) from top to bottom. The surface metal pattern layer (8) includes two sets of patterned metal sheets arranged in a mirror symmetry. Each set of patterned metal sheets includes a hexagonal metal sheet (12) and a first connecting metal sheet (13). The hexagonal metal sheet (12) and the first connecting metal sheet (13) are connected by an inductor (11). The hexagonal metal sheet (12) is composed of an isosceles trapezoidal metal sheet and a rectangular... Composed of metal sheets, the bottom edge of the isosceles trapezoidal metal sheet coincides with the long side of the rectangular metal sheet and is continuously spliced; the two hexagonal metal sheets (12) in the two sets of patterned metal sheets are spaced apart, and their trapezoidal top edges are arranged in parallel and connected by varactor diodes (10); the back metal pattern layer (7) includes two second connecting metal sheets, which are respectively connected to the two voltage output terminals of photodiodes (9); the two first connecting metal sheets (13) in the surface metal pattern layer (8) and the two second connecting metal sheets in the back metal pattern layer (7) are respectively connected by conductors that penetrate the multilayer composite structure, and the conductors are insulated from the metal ground layer (16) when passing through the metal ground layer (16); The fiber optic control unit contains the same number of optical paths as the metasurface units in the time-domain reflective metasurface array (6). All optical paths are connected one-to-one to the input terminals of photodiodes (9) on the back of different metasurface units. Each optical path can independently control the light intensity of the input photodiode (9). By controlling the light intensity of each optical path, the output voltage of the photodiodes (9) on different metasurface units in the time-domain reflective metasurface array (6) and the bias voltage across the varactor diodes (10) are changed, so that different metasurface units generate corresponding microwave reflection harmonic distributions, thereby directly mapping the optical signal onto the microwave signal.

2. The spatial phased array based on metasurface according to claim 1, characterized in that, In the metasurface unit, the first connecting metal sheet (13) is a rectangular metal sheet, and the second connecting metal sheet is an L-shaped metal sheet. The two are connected by a metal pillar. The metal pillar is installed in the through hole (14) of the multi-layer composite structure.

3. The spatial phased array based on metasurface according to claim 2, characterized in that, The metal column is insulated from the metal ground layer (16) at the location where it passes through the metal ground layer (16) by wrapping a ring-shaped dielectric layer around the metal column.

4. The spatial phased array based on metasurface according to claim 1, characterized in that, In the time-domain reflective metasurface array (6), the metasurface units are arranged periodically and continuously in an n*n rectangular array form, where n is an integer not less than 2.

5. The spatial phased array based on metasurface according to claim 1, characterized in that, The fiber optic control unit includes a laser (1), an optical fiber (2), a beam splitter (3), and an attenuator (4). The light source generated by the laser (1) is input into the optical fiber (2). The optical fiber (2) is split into multiple optical paths by a multi-stage beam splitter (3) to form multiple optical path signals. Each optical path signal is connected to a photodiode (9) on the back of a metasurface unit after passing through an independent attenuator (4). The fiber optic control unit controls the light intensity of each optical path signal input photodiode (9) by controlling the distribution ratio of each beam splitter (3) and the attenuation of each attenuator (4).

6. The spatial phased array based on metasurface according to claim 1, characterized in that, In the optical fiber control unit, the optical fiber (2) is split into two optical paths each time it passes through a beam splitter (3). The total number of optical path signals formed by the multi-stage beam splitter (3) is the same as the number of metasurface units in the domain reflective metasurface array (6).

7. The spatial phased array based on metasurface according to claim 1, characterized in that, The surface metal pattern layer (8), the metal ground layer (16), and the back metal pattern layer (7) are all made of copper.

8. The spatial phased array based on metasurface according to claim 2, characterized in that, The first dielectric layer (15), the second dielectric layer (17) and the annular dielectric layer are all made of polytetrafluoroethylene glass cloth copper-clad foil F4B, with a dielectric constant of 2.65 and a loss tangent of 0.

001.

9. The spatial phased array based on metasurface according to claim 2, characterized in that, The metasurface unit is a square plane with a side length of 16mm; the first dielectric layer (15), the second dielectric layer (17) and the metal ground layer (16) are also squares with a side length of 16mm; in the hexagonal metal sheet (12), the top side of the isosceles trapezoidal metal sheet is 4mm long, the bottom side is 12mm long, the trapezoidal height is 3.6mm, and the rectangular metal sheet is 12mm long and 2mm wide.

10. A method for controlling the reflection direction of a spatial phased array as described in any one of claims 1 to 9, characterized in that, Based on the target reflection direction of the metasurface reflection beam, by controlling the distribution ratio of each beam splitter (3) and the attenuation value of each attenuator (4) in the fiber optic control unit, the input light intensity of the photodiode (9), the output voltage of the photodiode (9), the bias voltage across the varactor diode (10), and the reflection phase of the metasurface unit on the incident microwave are correlated and changed, so that the reflection phase of all metasurface units on the time-domain reflective metasurface array (6) presents a distribution state that decreases equally toward the target reflection direction, thereby reflecting the incident microwave along the target reflection direction.

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