Reconfigurable super-lattice based on polarization conversion unit and electrically controlled diffraction method thereof

Abstract

The application belongs to the technical field of electromagnetic super surface and super grating, and discloses a reconfigurable super grating based on a polarization conversion unit and an electrically-controlled diffraction method thereof, which comprises a plurality of periodically arranged polarization conversion units, and adjacent polarization conversion units are arranged with a rotation of 90 degrees; the polarization conversion unit comprises a radiation layer and a feeding layer, the radiation layer is provided with a metal polarization conversion structure and a PIN diode, the PIN diode is loaded in the metal polarization conversion structure, the feeding layer is electrically connected with the PIN diode, and is used for providing a bias voltage to the PIN diode.The application integrates the functions of electrically-controlled polarization conversion, polarization-selective diffraction, different-polarization-wave separation and diffraction-amplitude adjustment in the same structure, adjusts the energy distribution of different diffraction orders through the on-off state of the PIN diode, and thus realizes the coexistence of polarization conversion, polarization separation, diffraction modes and electrically-controlled regulation of diffraction amplitude.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic metasurfaces and supergratings, and in particular to a reconfigurable supergrating based on a polarization conversion unit and its electrically controlled diffraction method. Background Technology

[0002] Metasurfaces are two-dimensional electromagnetic functional structures formed by the arrangement of artificial microstructural units in a specific manner. They can control the amplitude, phase, polarization, and propagation direction of electromagnetic waves within a subwavelength thickness. Compared with traditional bulk materials or conventional array structures, metasurfaces have the advantages of thin and lightweight structures, high design freedom, and easy integration, and have important application value in fields such as beam manipulation, polarization conversion, radar scattering control, wireless communication, and reconfigurable electromagnetic devices.

[0003] Supergratings are an important form of metasurface used for diffraction beam manipulation. By designing the unit cell structure, phase distribution, and array arrangement, supergratings can distribute the energy of incident electromagnetic waves to different diffraction orders, achieving functions such as zero-order suppression, anomalous reflection, beam splitting, multi-channel diffraction, and diffraction energy distribution. Compared with traditional gratings, supergratings can not only provide a more flexible electromagnetic response using artificial units, but also, by combining polarization conversion and active control devices, achieve richer adjustments to diffraction modes. Therefore, supergratings have good application potential in scenarios such as microwave beam splitting, polarization-multiplexed communication, and reconfigurable beam control.

[0004] Most existing microwave supergratings are designed for single polarization or fixed diffraction modes, and their diffraction characteristics are usually predetermined by the unit structure and array arrangement. Once the structure is fabricated, the distribution of incident wave energy in each diffraction order is usually difficult to change dynamically, resulting in a relatively fixed operating mode, which makes it difficult to meet the application requirements of different polarization wave separation, diffraction mode switching, and diffraction amplitude control.

[0005] Furthermore, while some existing supergratings or reconfigurable metasurfaces can achieve certain electromagnetic response switching by loading active devices such as PIN diodes, most designs mainly focus on phase or amplitude modulation under a single polarization, rarely considering the synergistic relationship between unit polarization conversion characteristics and array diffraction modes. For incident waves with different polarizations, existing structures often struggle to allocate them to different diffraction channels, and it is also difficult to simultaneously achieve electrically controlled adjustment of the amplitudes of zero-order diffraction, ±1st-order diffraction, and different diffraction orders.

[0006] In terms of polarization conversion, existing polarization conversion units can usually only achieve a single function, such as linear polarization to cross polarization conversion or linear polarization to circular polarization conversion. It is difficult to switch different polarization response states in the same unit through electronic control. If only fixed polarization conversion units are used for array arrangement, the polarization response and diffraction mode are relatively simple, making it difficult to achieve the integration of polarization conversion, polarization separation and diffraction amplitude control.

[0007] Therefore, it is necessary to propose a new supergrating structure to solve the problems of existing microwave supergrating structures, such as single function, fixed diffraction mode, difficulty in separating different polarization waves, and difficulty in dynamically controlling diffraction amplitude. Summary of the Invention

[0008] The purpose of this invention is to provide a reconfigurable supergrating based on a polarization conversion unit and its electrically controlled diffraction method, which solves the problems of existing microwave supergratings having single function, fixed diffraction modes, difficulty in separating different polarization waves, and difficulty in dynamically controlling the diffraction amplitude.

[0009] To achieve the above objectives, the present invention employs the following technical solution: A reconfigurable supergrating based on polarization conversion units includes several periodically arranged polarization conversion units, with adjacent polarization conversion units rotated 90° apart. The polarization conversion unit includes a radiating layer and a feeding layer. The radiating layer is provided with a metal polarization conversion structure and a PIN diode. The PIN diode is loaded in the metal polarization conversion structure. The feeding layer is electrically connected to the PIN diode and is used to provide a bias voltage to the PIN diode.

[0010] Furthermore, the polarization conversion unit also includes a dielectric substrate and a metal ground layer. The dielectric substrate has several dielectric layers disposed therein, and the metal ground layer is disposed in the middle of the dielectric substrate or between adjacent dielectric layers.

[0011] Furthermore, the radiating layer is disposed on one side of the dielectric substrate, and the feeding layer is disposed on the other side of the dielectric substrate.

[0012] Furthermore, a clearance zone is set in the metallic stratum, and the clearance zone corresponds to the metallized via.

[0013] Furthermore, metallized vias are disposed in the metal feed structure, which is electrically connected to the PIN diode through the metallized vias. The metal feed structure is disposed in the feed layer.

[0014] Furthermore, the feed layer is also provided with a radio frequency isolation structure, which includes a fan-shaped structure, a stub structure, and a high impedance line structure.

[0015] An electrically controlled diffraction method based on a reconfigurable supergrating using a polarization conversion unit, comprising: Several polarization conversion units were first arranged in a unidirectional flat arrangement to form an array structure, and the polarization conversion performance of the polarization conversion units under different PIN diode states was verified. Adjacent polarization conversion units are rotated 90° and arranged periodically to distribute different polarization waves into different diffraction channels for polarization-selective diffraction. The feed layer applies a bias voltage to the polarization conversion unit, controlling the PIN diode to be in the on or off state, performing different polarization wave conversions, and realizing the electronic control adjustment of diffraction mode and diffraction amplitude.

[0016] Furthermore, the method for polarization-selective diffraction is as follows: For the X-polarization component, the adjacent polarization conversion unit generates a 180° phase difference before and after rotation, causing the X-polarized incident wave to cancel each other in the 0th order direction, thereby suppressing the X-polarized 0th order diffraction and forming ±1st order diffraction. For the Y-polarization component, adjacent polarization conversion units before and after rotation maintain a relatively consistent phase response, so that the Y-polarized incident wave remains coherently superimposed in the 0th order direction, thus forming 0th order diffraction.

[0017] Furthermore, the method for converting different polarization waves is as follows: When the PIN diode is in the off state, the polarization conversion unit converts the incident linear polarization wave into a cross-polarization wave; When the PIN diode is in the conducting state, the polarization conversion unit causes the incident ray polarization wave to generate a main polarization component and a cross polarization component. The main polarization component and the cross polarization component have similar amplitudes and their phase difference satisfies the circular polarization condition, thereby outputting a circularly polarized wave or an approximately circularly polarized wave.

[0018] Furthermore, the electronic control method for adjusting the diffraction mode and diffraction amplitude is as follows: When a PIN diode is in the on or off state, the main polarization component, cross polarization component, and their phase relationship of the polarization conversion unit will change, and the energy distribution of the ±1st order X-polarization diffraction and the 0th order Y-polarization diffraction will change accordingly, thus adjusting the amplitude distribution of different diffraction orders.

[0019] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a reconfigurable supergrating based on polarization conversion units. The supergrating is composed of several periodically arranged polarization conversion units, each layered with a radiation layer and a feed layer. The radiation layer incorporates a metal polarization conversion structure and embeds a PIN diode. The feed layer stably supplies bias voltage to the diode to control its on / off state, allowing the same unit to switch between different polarization response states via electronic control. This adjusts the main polarization component, cross-polarization component, and their phase relationship within the polarization conversion unit, increasing the degree of freedom in unit polarization control. Furthermore, by rotating adjacent polarization conversion units by 90°, a polarization-related phase difference can be formed at the array level, thereby distributing different polarization waves to different diffraction orders. The energy distribution of each diffraction order can then be further adjusted electronically. This invention uses a polarization conversion unit with loaded PIN diodes as the basic unit and employs an array arrangement where adjacent units are rotated 90°. This allows incident waves with different polarizations to be distributed into different diffraction orders. Simultaneously, the energy distribution of different diffraction orders is adjusted by controlling the on / off state of the PIN diodes, thereby achieving polarization conversion, polarization separation, coexistence of diffraction modes, and electrically controlled diffraction amplitude modulation. Compared to traditional single-polarization or fixed-diffraction-mode supergratings, this invention integrates electrically controlled polarization conversion, polarization-selective diffraction, separation of different polarizations, and diffraction amplitude adjustment functions within the same structure. It boasts advantages such as high functional complexity, compact structure, and ease of array-based control. It solves the problems of existing microwave supergratings having single function, fixed diffraction modes, difficulty in separating different polarizations, and difficulty in dynamically controlling diffraction amplitude. It can be used in fields such as polarization-multiplexed communication, reconfigurable beamforming, and microwave functional devices.

[0020] Furthermore, this invention employs a bottom-layer feed layer and metallized vias to bias the PIN diodes, and reduces the impact of the feed line on the RF response through an RF isolation structure, which is beneficial for achieving unified bias control and reconfigurable adjustment in the array structure.

[0021] This invention also provides an electrically controlled diffraction method based on a reconfigurable supergrating using a polarization conversion unit. By combining the polarization conversion unit with a rotating supergrating structure, X-polarized waves and Y-polarized waves correspond to different diffraction modes, thereby achieving polarization-selective diffraction and the coexistence of multiple diffraction modes within the same supergrating structure. Furthermore, by switching the on / off state of a PIN diode, the energy distribution of different diffraction orders can be adjusted, realizing electrically controlled modulation of diffraction modes and diffraction amplitude. This invention combines unit-level electrically controlled polarization conversion, array-level polarization separation, and diffraction mode modulation, offering advantages such as compact structure, functional integration, and ease of array-based control. It overcomes the problem that existing microwave supergratings mostly operate for single polarization or fixed diffraction modes, making it difficult to simultaneously achieve polarization conversion, separation of different polarization waves, and electrically controlled adjustment of diffraction amplitude. Polarization conversion, polarization separation, zero-order suppression, ±1st order diffraction, and diffraction amplitude modulation are achieved within the same supergrating structure. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the array structure formed by arranging the polarization conversion units in the same direction according to the present invention.

[0024] Figure 2 This is a schematic diagram of the electrotunable diffraction mode supergrating structure formed by arranging adjacent polarization conversion units rotated by 90° according to the present invention.

[0025] Figure 3 This is a schematic diagram of the overall structure of the polarization conversion unit of the present invention.

[0026] Figure 4 This is a schematic diagram of the radiation layer structure of the polarization conversion unit of the present invention.

[0027] Figure 5 This is a schematic diagram of the feed layer structure of the polarization conversion unit of the present invention.

[0028] Figure 6 shows the polarization amplitude and phase diagrams of the polarization conversion unit of the present invention under different states of the PIN diode, where (a) is the polarization amplitude and phase diagram of the X and Y polarization when the diode is off, and (b) is the polarization amplitude and phase diagram of the X and Y polarization when the diode is on.

[0029] Figure 7 shows the polarization conversion performance of the polarization conversion unit in Embodiment 1 of the present invention before and after applying the bias circuit under different states of the PIN diode. (a) shows the polarization conversion performance before and after applying the bias circuit when the diode is off, and (b) shows the polarization conversion performance before and after applying the bias circuit when the diode is on.

[0030] Figure 8 shows the diffraction amplitude modulation results of adjacent supergratings rotated 90° in Embodiment 3 of the present invention under the PIN diode on and off states, where (a) is the diffraction amplitude modulation result when the diode is on and (b) is the diffraction amplitude modulation result when the diode is off.

[0031] Among them, 1-dielectric substrate, 2-radiating layer, 3-feed layer, 4-metal ground layer, 5-metal polarization conversion structure, 6-PIN diode, 7-metal feed line structure, 8-RF isolation structure, 9-metallized via, 10-avoidance area. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0033] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0034] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0035] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0036] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0037] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0038] The present invention will now be described in further detail with reference to the accompanying drawings: See Figure 3 The present invention provides a reconfigurable supergrating based on polarization conversion units, comprising a number of periodically arranged polarization conversion units, and forming a supergrating array by rotating adjacent polarization conversion units by 90°, for realizing polarization-selective diffraction, separation of different polarization waves, and electronically controlled adjustment of diffraction amplitude, so that adjacent polarization conversion units before and after rotation produce different phase responses to different polarization components.

[0039] The polarization conversion unit includes a dielectric substrate 1, in which a plurality of dielectric layers are disposed, and a metal ground layer 4 is disposed in the middle of the dielectric substrate 1 or between adjacent dielectric layers. A radiating layer 2 is disposed on one side of the dielectric substrate 1, and a feeding layer 3 is disposed on the other side of the dielectric substrate 1.

[0040] like Figure 4 As shown, the radiating layer 2 includes a metal polarization conversion structure 5 and a PIN diode 6 loaded in the metal polarization conversion structure 5. The metal polarization conversion structure 5 is used to generate a polarization conversion response to the incident ray polarized wave. The PIN diode 6 is used to change the equivalent current path and resonant state of the radiating layer 2.

[0041] like Figure 5As shown, the feed layer 3 is disposed at the bottom of the polarization conversion unit and is used to provide bias voltage to the PIN diode 6. It includes a metal feed line structure 7 for transmitting bias signals and an RF isolation structure 8. The metal feed line structure 7 is electrically connected to the PIN diode 6 through a metallized via 9, and is used to apply bias voltage to the PIN diode 6 to control its on / off state. By changing the on / off state of the PIN diode 6, the amplitude distribution of different diffraction orders can be further adjusted, realizing the electronic control adjustment of the diffraction mode and diffraction amplitude, so that the same polarization conversion unit has different electromagnetic response states. The RF isolation structure 8 is used to reduce the influence of the metal feed line structure 7 on the RF response of the radiating layer 2. The RF isolation structure 8 can be a fan-shaped structure, a stub structure, a high-impedance line structure, or other isolation structures that can suppress RF leakage.

[0042] The metal ground layer 4 is used to form a reflective electromagnetic structure and to isolate the radio frequency coupling between the radiating layer 2 and the feed layer 3. A clearance region 10 corresponding to the metallized via 9 is provided in the metal ground layer 4 to prevent the bias path from being directly short-circuited with the metal ground layer 4.

[0043] The present invention also provides an electrically controlled diffraction method based on a reconfigurable supergrating of polarization conversion unit, which can distribute different polarization waves to different diffraction channels to achieve polarization-selective diffraction and separation of different polarization waves.

[0044] Several polarization conversion units are first arranged in a unidirectional, tiled array to characterize or verify the polarization conversion performance of the polarization conversion units under different PIN diode 6 states. Specifically, this includes the linear to cross-polarization conversion when PIN diode 6 is off, and the linear to circular or near-circular polarization conversion when PIN diode 6 is on. The unidirectional, tiled array is used to illustrate the electrically controlled polarization conversion capability of the polarization conversion units themselves and is not the final array form for achieving diffraction mode control in this invention.

[0045] A number of polarization conversion units are periodically arranged with adjacent units rotated by 90° to form an electrically tunable diffraction mode supergrating. For the X-polarization component, the adjacent polarization conversion units before and after the rotation generate a 180° phase difference, causing the X-polarized incident wave to destructively phase in the 0th order direction, thereby suppressing the 0th order X-polarization diffraction and forming ±1st order diffraction. For the Y-polarization component, the adjacent polarization conversion units before and after the rotation maintain a relatively consistent phase response, causing the Y-polarized incident wave to coherently superimpose in the 0th order direction, thus mainly forming the 0th order diffraction.

[0046] The polarization conversion unit controls the on / off state of the PIN diode 6 in the supergrating array by applying an external bias voltage, switching between cross-polarization conversion and circular or near-circular polarization conversion. When the PIN diode 6 is off, the polarization conversion unit converts the incident ray-polarized wave into a cross-polarized wave; when the PIN diode 6 is on, the polarization conversion unit generates a main polarization component and a cross-polarization component in the incident ray-polarized wave. The main polarization component and the cross-polarization component have similar amplitudes and a phase difference that satisfies the circular polarization condition, thus outputting a circular or near-circular polarized wave. Because the main polarization component, the cross-polarization component, and their phase relationship change under different PIN states, the energy distribution of the ±1st order X-polarized diffraction and the 0th order Y-polarized diffraction in adjacent supergratings rotated 90° changes accordingly, thereby achieving electronically controlled adjustment of the diffraction mode and diffraction amplitude.

[0047] The technical solution of the present invention will be further described in detail below through specific embodiments: Example 1: This embodiment provides a polarization conversion unit with a PIN diode 6 loaded. The polarization conversion unit comprises a three-layer structure: an upper radiating layer 2, a middle metal ground layer 4, and a lower feed layer 3. The upper radiating layer 2 has a metal polarization conversion structure 5, and a PIN diode 6 is loaded within the metal polarization conversion structure 5. The middle metal ground layer 4 forms a reflective unit structure and isolates the upper RF radiating structure from the lower feed structure. The lower feed layer 3 provides a bias voltage to the PIN diode 6.

[0048] In this embodiment, the period of the polarization conversion unit is 20 mm. The geometric dimensions of the metal polarization conversion structure 5 of the radiating layer 2 can be set as follows: l1 = 7 mm, l2 = 9.2 mm, l3 = 3 mm, w1 = 1.2 mm. These dimensional parameters, together with the PIN diode 6, constitute a switchable polarization conversion unit, enabling the unit to generate different equivalent current paths and polarization responses under different bias states. The PIN diode 6 is of model MADP-000907-14020x.

[0049] The feed layer 3 is electrically connected to the PIN diode 6 in the upper radiating layer 2 via a metallized via 9. The metallized via 9 passes through the dielectric substrate 1 and is electrically isolated from the metal ground layer 4 through a clearance region 10 in the metal ground layer 4, thereby preventing a short circuit between the bias path and the metal ground layer 4. The feed layer 3 adopts a fan-shaped structure as the RF isolation structure 8 to reduce the impact of the bias feed network on the RF response of the polarization conversion unit.

[0050] When PIN diode 6 is in the off state, the equivalent current path of the polarization conversion unit corresponds to the cross-polarization conversion state. The incident linearly polarized wave is converted into a cross-polarized wave after being processed by the unit. As shown in Figure 6(a), when PIN diode 6 is off, the cross-polarization reflection amplitude rxy remains at a high level within the operating frequency band, while the same polarization reflection amplitude ryy is significantly lower than the cross-polarization reflection amplitude, and the phase difference Δφ between the two is close to 180°, indicating that the unit can achieve the conversion from linear polarization to cross-polarization in this state. The polarization conversion unit has a polarization conversion rate greater than 80% in the frequency band of 4.65~10.39 GHz in this state, as shown in Figure 7(a).

[0051] When PIN diode 6 is in the ON state, the equivalent current path of the polarization conversion unit changes, and the incident ray polarized wave generates a main polarization component and a cross-polarization component after passing through the unit. As shown in Figure 6(b), in the ON state, the amplitudes of the main polarization component and the cross-polarization component are close, and the phase difference is close to 270°, thus generating a circularly polarized wave or an approximately circularly polarized wave. Among them, the frequency band with an axial ratio of less than 3 dB is 6.6~9.23 GHz, as shown in Figure 7(b).

[0052] The above results show that the polarization conversion unit in this embodiment can achieve two polarization responses, namely linear polarization to cross polarization conversion and linear polarization to circular polarization or near-circular polarization conversion, by switching the conduction and disconnection states of PIN diode 6.

[0053] Example 2: This embodiment provides a co-directional tiled array for verifying the polarization response performance of the polarization conversion unit.

[0054] The polarization conversion units of Example 1 are periodically replicated and tiled in the same direction to form a unidirectional tiled array, such as... Figure 1 As shown, the co-directional tiled array consists of 16×16 polarization conversion units.

[0055] When all PIN diodes 6 in the same-direction tiled array are in the off state, each polarization conversion unit is in the cross-polarization conversion state, and the array as a whole exhibits the function of linear polarization to cross-polarization conversion. When all PIN diodes 6 in the same-direction tiled array are in the on state, each polarization conversion unit is in the circular polarization or near-circular polarization conversion state, and the array as a whole exhibits the function of linear polarization to circular polarization conversion.

[0056] The co-directional tiled array in this embodiment demonstrates that the polarization conversion unit itself has electronically controlled polarization conversion capability.

[0057] Example 3: This embodiment provides an electrically tunable diffraction mode supergrating based on the 90° rotation of adjacent polarization conversion units: Based on the polarization conversion units described in Embodiment 1, adjacent polarization conversion units are rotated by 90° and then periodically arranged to form a rotated supergrating, such as... Figure 2 As shown, the rotating supergrating consists of 16×16 polarization conversion units, with adjacent units alternating between 0°, 90°, 0°, and 90°.

[0058] For X-polarized incident light, the adjacent polarization conversion units before and after rotation generate a 180° phase difference in their X-polarized responses, causing destructive interference between adjacent units in the 0th-order direction. This suppresses the 0th-order diffraction of X-polarized light and forms +1 and -1-order diffraction. For Y-polarized incident light, the phase of the adjacent polarization conversion units before and after rotation remains essentially unchanged in their Y-polarized responses, causing coherent superposition of Y-polarized energy in the 0th-order direction, thus primarily forming 0th-order diffraction. Therefore, the rotating arrangement supergrating of this embodiment can distribute X-polarized and Y-polarized waves to different diffraction channels, achieving separation of different polarizations and coexistence of multiple diffraction modes.

[0059] By controlling the on and off states of PIN diode 6, the amplitude distributions of the ±1st order diffraction of X-polarization and the 0th order diffraction of Y-polarization can be further adjusted. When PIN diode 6 is in the on state, the ±1st order diffraction amplitude of X-polarization is relatively low, with a maximum of approximately 0.05; the 0th order diffraction amplitude of Y-polarization is relatively high, with a maximum of approximately 0.55, as shown in Figure 8(a). When PIN diode 6 is in the off state, the ±1st order diffraction amplitude of X-polarization increases, with a maximum of approximately 0.13; the 0th order diffraction amplitude of Y-polarization decreases, with a maximum of approximately 0.2, as shown in Figure 8(b).

[0060] This embodiment illustrates that the rotating arrangement of supergratings can not only separate the diffraction channels of different polarization waves, but also adjust the amplitude distribution of different diffraction orders by switching the on and off states of PIN diode 6, thereby achieving electronic control of the diffraction mode and diffraction amplitude.

[0061] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A reconfigurable supergrating based on a polarization conversion unit, characterized in that, It includes several periodically arranged polarization conversion units, with adjacent polarization conversion units rotated 90° apart; The polarization conversion unit includes a radiation layer (2) and a feed layer (3). The radiation layer (2) is provided with a metal polarization conversion structure (5) and a PIN diode (6). The PIN diode (6) is loaded in the metal polarization conversion structure (5). The feed layer (3) is electrically connected to the PIN diode (6) and is used to provide a bias voltage to the PIN diode (6).

2. The reconfigurable supergrating based on a polarization conversion unit according to claim 1, characterized in that, The polarization conversion unit also includes a dielectric substrate (1) and a metal ground layer (4). The dielectric substrate (1) has several dielectric layers, and the metal ground layer (4) is disposed in the middle of the dielectric substrate (1) or between adjacent dielectric layers.

3. The reconfigurable supergrating based on a polarization conversion unit according to claim 2, characterized in that, The radiating layer (2) is disposed on one side of the dielectric substrate (1), and the feeding layer (3) is disposed on the other side of the dielectric substrate (1).

4. The reconfigurable supergrating based on a polarization conversion unit according to claim 2, characterized in that, An avoidance zone (10) is provided in the metal formation (4), and the avoidance zone (10) corresponds to the metallized via (9).

5. The reconfigurable supergrating based on a polarization conversion unit according to claim 4, characterized in that, Metallized vias (9) are disposed in the metal feed structure (7), and the metal feed structure (7) is electrically connected to the PIN diode (6) through the metallized vias (9). The metal feed structure (7) is disposed in the feed layer (3).

6. The reconfigurable supergrating based on a polarization conversion unit according to claim 1, characterized in that, The feed layer (3) is also provided with a radio frequency isolation structure (8), which includes a fan-shaped structure, a stub structure and a high impedance line structure.

7. An electrically controlled diffraction method based on a reconfigurable supergrating according to any one of claims 1 to 6, characterized in that, include: Several polarization conversion units are first arranged in a unidirectional flat manner to form an array structure, and the polarization conversion performance of the polarization conversion units under different PIN diode (6) states is verified; Adjacent polarization conversion units are rotated 90° and arranged periodically to distribute different polarization waves into different diffraction channels for polarization-selective diffraction. The feed layer (3) applies a bias voltage to the polarization conversion unit, controls the PIN diode (6) to be in the on or off state, performs different polarization wave conversion, and realizes the electronic control adjustment of diffraction mode and diffraction amplitude.

8. The electrically controlled diffraction method based on a reconfigurable supergrating according to claim 7, characterized in that, The method of polarization-selective diffraction is as follows: For the X-polarization component, the adjacent polarization conversion unit generates a 180° phase difference before and after rotation, causing the X-polarized incident wave to cancel each other in the 0th order direction, thereby suppressing the X-polarized 0th order diffraction and forming ±1st order diffraction. For the Y-polarization component, adjacent polarization conversion units before and after rotation maintain a relatively consistent phase response, so that the Y-polarized incident wave remains coherently superimposed in the 0th order direction, thus forming 0th order diffraction.

9. The electrically controlled diffraction method based on a reconfigurable supergrating according to claim 7, characterized in that, The methods for converting different polarization waves are as follows: When the PIN diode (6) is in the off state, the polarization conversion unit converts the incident linear polarization wave into a cross-polarization wave; When the PIN diode (6) is in the conducting state, the polarization conversion unit causes the incident ray polarization wave to generate a main polarization component and a cross polarization component. The main polarization component and the cross polarization component have similar amplitudes and the phase difference satisfies the circular polarization condition, thereby outputting a circular polarization wave or an approximately circular polarization wave.

10. The electrically controlled diffraction method based on a reconfigurable supergrating according to claim 7, characterized in that, The electronic control adjustment method for diffraction mode and diffraction amplitude is as follows: When the PIN diode (6) is in the on or off state, the main polarization component, cross polarization component and their phase relationship of the polarization conversion unit will change, and the energy distribution of the ±1st order diffraction of X polarization and the 0th order diffraction of Y polarization will change accordingly, thus adjusting the amplitude distribution of different diffraction orders.

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