Metasurface unit and metasurface

Abstract

The disclosure provides a metasurface unit and a metasurface. The metasurface unit comprises a metal ground layer, a liquid crystal layer arranged on the metal ground layer, and at least one metal patch arranged on a side of the liquid crystal layer away from the metal ground layer. The at least one metal patch is connected to a power supply through a bias line. The at least one metal patch is rectangular, and the extension directions of the long sides of the at least one metal patch are the same. The metasurface unit provided by the disclosure has a single polarization direction, prevents cross polarization, ensures the reflection quality of the metasurface, and avoids occupying cross polarization resources. The metasurface unit provided by the disclosure has multi-frequency working capability. Meanwhile, the reflection and / or scattering amplitude and the reflection and / or scattering phase of the metasurface unit provided by the disclosure are continuously adjustable, the flexibility of adjusting the reflection and / or scattering amplitude and the reflection and / or scattering phase of the metasurface unit is improved, and the range of the working frequency band of the metasurface unit provided by the disclosure is relatively large.

Description

Technical Field

[0001] This disclosure relates to the field of metasurface technology, and more particularly to a metasurface unit and a metasurface. Background Technology

[0002] Metasurfaces are a novel technology that has emerged in recent years, consisting of periodic or aperiodic arrangements of metasurface units. As a two-dimensional form of metamaterials, metasurfaces play an increasingly important role in many scientific fields such as electromagnetics, optics, acoustics, and thermodynamics. Liquid crystals, being a common tunable material in the millimeter-wave band with relatively low dielectric loss and optical transparency, are often incorporated into metasurfaces to achieve phase and / or amplitude modulation.

[0003] In related technologies, the metasurface unit of the liquid crystal-modulated metasurface adopts an anisotropic structure with two polarization directions, each operating in a frequency band. By adjusting the dielectric constant of the liquid crystal material in the metasurface unit, the phase response of the metasurface unit in different polarization directions is changed, thereby constructing a metasurface with dual-frequency operation capability.

[0004] However, in related technologies, since the metasurface unit has two different polarization directions and these two polarization directions operate in the same frequency band, cross-polarization may occur, which may affect the reflection quality of the metasurface and also occupy cross-polarization resources. Summary of the Invention

[0005] The metasurface unit and metasurface proposed in this disclosure are millimeter-wave single-polarization dual-frequency reflective metasurfaces based on liquid crystal modulation, which can avoid cross-polarization, ensure the reflection quality of the metasurface, and not occupy cross-polarization resources.

[0006] In a first aspect, embodiments of this disclosure provide a metasurface unit, comprising:

[0007] Metallic strata;

[0008] A liquid crystal layer, wherein the liquid crystal layer is disposed on the metal ground layer;

[0009] At least one metal patch is disposed on the side of the liquid crystal layer away from the metal ground layer, and the at least one metal patch is connected to a power supply via a bias line; the at least one metal patch is rectangular, and the long sides of the at least one metal patch extend in the same direction.

[0010] The metasurface unit provided in this disclosure achieves a single polarization direction by ensuring that the long sides of at least one rectangular metal patch extend in the same direction, preventing cross-polarization, ensuring the reflection quality of the metasurface, and avoiding the occupation of cross-polarization resources. Furthermore, by using at least one rectangular metal patch with different sizes, the metasurface unit achieves multi-frequency operation capability. Simultaneously, by utilizing a liquid crystal layer as a tunable material to construct the metasurface unit, the reflection and / or scattering amplitude and phase of the metasurface unit are continuously adjustable, improving the flexibility of adjusting these parameters. Moreover, due to the low insertion loss of liquid crystal and its high practical applicability, when using liquid crystal as a tunable material, the operating frequency band of the metasurface unit can reach millimeter-wave or even terahertz bands, thus expanding the operating frequency range of the metasurface unit.

[0011] Secondly, embodiments of this disclosure provide a metasurface, comprising:

[0012] At least one metasurface unit as described in the first aspect above. Attached Figure Description

[0013] The above and / or additional aspects and advantages of this disclosure will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, in which:

[0014] Figure 1 This is a top view schematic diagram of a metasurface unit provided in an embodiment of the present disclosure;

[0015] Figure 2 This is a side view schematic diagram of a metasurface unit provided in an embodiment of the present disclosure;

[0016] Figure 3 This is a schematic diagram illustrating the changes in the reflection and / or scattering amplitude and phase of the metasurface unit when the dielectric constant of the liquid crystal layer 5 of the metasurface unit is different under incident beams of different frequencies, according to an embodiment of this disclosure.

[0017] Figure 4 Two-dimensional far-field radiation patterns of the metasurface under different phase periods when the incident beam frequency is 23.1 GHz;

[0018] Figure 5 The image shows the two-dimensional far-field radiation pattern of the metasurface under different phase periods when the incident beam frequency is 29.8 GHz. Detailed Implementation

[0019] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with those of this disclosure. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the embodiments of this disclosure as detailed in the appended claims.

[0020] The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. The singular forms “a” and “the” as used in this disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

[0021] It should be understood that although the terms first, second, third, etc., may be used to describe various information in embodiments of this disclosure, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, first information may also be referred to as second information without departing from the scope of embodiments of this disclosure, and similarly, second information may also be referred to as first information. Depending on the context, the words “if” and “suppose” as used herein may be interpreted as “when”, “when”, or “in response to a determination”.

[0022] Embodiments of this disclosure are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this disclosure, and should not be construed as limiting this disclosure.

[0023] To facilitate understanding, the terminology used in this application will be introduced first.

[0024] 1. Metasurface

[0025] A metasurface is an artificially layered material with a thickness less than the wavelength of light. Metasurfaces allow for flexible and effective adjustment of the polarization, amplitude, phase, polarization, and propagation mode of electromagnetic waves. A metasurface can be considered a two-dimensional counterpart to a metamaterial.

[0026] The metasurface unit and metasurface provided in the embodiments of this disclosure will be described in detail below with reference to the accompanying drawings.

[0027] Figure 1 This is a top view schematic diagram of a metasurface unit provided in an embodiment of this disclosure. Figure 2 This is a side view schematic diagram of a metasurface unit provided in an embodiment of this disclosure, as shown below. Figure 1 and 2 As shown, the metasurface unit may include:

[0028] Metallic strata 6 (i.e.) Figure 1 and Figure 2 The metal ground shown is 6);

[0029] Liquid crystal layer 5 (i.e.) Figure 1 and Figure 2 The liquid crystal material 5 shown in the figure is disposed on the metal ground layer 6;

[0030] At least one metal patch ( Figure 1 and Figure 2 (Taking the example of setting metal patches 2 and 3 as an example), at least one metal patch is disposed on the side of the liquid crystal layer 5 away from the metal ground layer 6, and the at least one metal patch is connected to the power supply through a bias line 4; the at least one metal patch is rectangular, and the long sides of the at least one metal patch extend in the same direction, as shown in the reference. Figure 1 and Figure 2 The long sides of metal patch 2 and metal patch 3 extend in the Y direction shown in the figure.

[0031] In one embodiment of this disclosure, the aforementioned metal substrate 6 and the at least one metal patch can be used as reflectors and / or scatterers of the metasurface unit to reflect and / or scatter the incident beam.

[0032] It should be noted that when the metal patch is rectangular, its polarization direction when reflecting and / or scattering beams is related to the extension direction of the long side of the metal patch. Based on this, in one embodiment of this disclosure, by making the extension direction of the long side of at least one metal patch the same, the polarization direction of the metasurface unit is made to be a single polarization direction, thus avoiding cross-polarization, ensuring the reflection quality of the metasurface, and avoiding the occupation of cross-polarization resources.

[0033] Furthermore, in one embodiment of this disclosure, the operating frequency band for reflecting and / or scattering incident beams varies depending on the size of the metal patch. The operating frequency band of the metal patch can be understood as the frequency band of the beam that the metal patch can reflect and / or scatter. For example, if the operating frequency band of the metal patch is 10 GHz to 20 GHz, then the beam that the metal patch can reflect and / or scatter is a beam with a frequency between 10 GHz and 20 GHz. In other words, the metal patch is mainly used to reflect and / or scatter incident beams with frequencies belonging to the corresponding operating frequency band of the metal patch.

[0034] Based on this, in one embodiment of this disclosure, the metasurface unit is equipped with multi-band operating capability (i.e., multi-band reflection and / or scattering capability) by making the different metal patches of the metasurface unit have different sizes. The different sizes of the different metal patches can indicate different lengths and / or different widths of the different metal patches, which correspondingly also means different areas of the different metal patches.

[0035] Furthermore, this disclosure primarily uses the example of a metasurface unit comprising two metal patches for illustration. These two metal patches can be: a first metal patch (i.e., Figure 1 and 2 Metal patch 2), second metal patch (i.e. Figure 1 and 2 Metal patch 3), wherein the first metal patch and the second metal patch are arranged side by side, that is, the extension direction of the long side of the first metal patch is the same as the extension direction of the long side of the second metal patch, and the size of the first metal patch is different from the size of the second metal patch, thereby constructing a single-polarization dual-frequency reflective metasurface unit.

[0036] Furthermore, in one embodiment of this disclosure, the metasurface unit may further include:

[0037] A first substrate is disposed on the side of the metal ground layer 6 away from the liquid crystal layer 5;

[0038] The second substrate is disposed on the side of the at least one metal patch away from the liquid crystal layer 5.

[0039] The first and second substrates can provide adhesion support for other layers, thereby restricting the flow of liquid crystal, and can also be used for encapsulating liquid crystal materials; and both the first and second substrates can be made of glass. (Reference) Figure 2 The first substrate can be Figure 2 The lower glass 7 and the second substrate can be Figure 2 The upper glass layer 1. The first and second substrates can be of type BF33. Of course, substrates of other materials are also possible.

[0040] Furthermore, in one embodiment of this disclosure, the aforementioned at least one metal patch may be made of the same metal material, such as copper or silver.

[0041] The above content is an introduction to the structure of the metasurface unit in this disclosure. As can be seen from the above content, the metasurface unit of this disclosure is mainly a single-polarization multi-frequency metasurface unit. However, the metasurface unit of this disclosure also has continuous tunability, which will be introduced below.

[0042] In one embodiment of this disclosure, the liquid crystal layer in the metasurface unit can be used as an adjustable material to adjust the reflection and / or scattering amplitude and the reflection and / or scattering phase of the metasurface unit. Furthermore, the adjustment of the reflection and / or scattering amplitude and the reflection and / or scattering phase of the metasurface unit based on the liquid crystal layer in this disclosure is continuously adjustable.

[0043] Specifically, in one embodiment of this disclosure, the metal ground layer 6 can also serve as the negative electrode of the DC bias, and at least one metal patch can serve as the positive electrode of the DC bias. Based on this, by adjusting the voltage of the power supply connected to the bias line 4, the voltage output to the metal patch can be changed, thereby changing the voltage drop across the liquid crystal layer 5, and consequently changing the dielectric constant of the liquid crystal layer 5. Furthermore, in one embodiment of this disclosure, when the dielectric constant of the liquid crystal layer 5 is different, the reflection and / or scattering amplitudes and phases of the incident beam reflected and / or scattered by the metal patch and the metal ground layer will also be different, thereby achieving tunability of the reflection and / or scattering amplitudes and phases of the metasurface unit.

[0044] Furthermore, it should be noted that in this disclosure, when the dielectric constant of the liquid crystal layer 5 is adjusted by regulating the voltage of the power supply, the dielectric constant of the liquid crystal layer 5 is continuously adjustable. Continuously adjustable can be understood as the dielectric constant of the liquid crystal layer 5 being continuously and non-discretely adjusted from one value to another. Based on this, since the dielectric constant of the liquid crystal layer 5 is continuously adjustable, the reflection and / or scattering amplitude and the reflection and / or scattering phase of the metasurface units can also be continuously adjusted.

[0045] As can be seen from the above, in this disclosure, the reflection and / or scattering amplitude and phase of the metasurface unit for the incident beam are related to the dielectric constant of the liquid crystal layer; the dielectric constant of the liquid crystal layer is related to the voltage of the power supply. Therefore, by adjusting the voltage of the power supply to change the dielectric constant of the liquid crystal layer of the metasurface unit, the reflection and / or scattering amplitude and phase of the metasurface unit can be continuously adjusted. Figure 3 This is a schematic diagram illustrating the changes in the reflection and / or scattering amplitude and phase of the metasurface unit when the dielectric constant of the liquid crystal layer 5 of the metasurface unit is different under incident beams of different frequencies, as provided in the embodiments of this disclosure. Figure 3 The following explanation is based on the dielectric constants ε of the liquid crystal layer 5 of the metasurface unit, which are ε = 2.4, ε = 2.9, ε = 3.4, and ε = 3.9.

[0046] in, Figure 3The four lines at the top of the diagram represent the changes in the reflection amplitude of the metasurface unit when the dielectric constant ε of the liquid crystal layer 5 of the metasurface unit is ε = 2.4, ε = 2.9, ε = 3.4, and ε = 3.9, respectively, for different incident beam frequencies. (Refer to...) Figure 3 It can be seen that when the dielectric constant ε of the liquid crystal layer 5 of the metasurface unit is ε=2.4, ε=2.9, ε=3.4, ε=3.9, and the frequency of the incident beam is 23.1GHz and 29.8GHz, the reflection amplitude of the metasurface unit is less than -2dB, so its reflection loss is low and the reflection accuracy is high.

[0047] as well as, Figure 3 The four lines at the bottom of the diagram represent the changes in the reflection phase of the metasurface unit when the dielectric constant ε of the liquid crystal layer 5 of the metasurface unit is ε = 2.4, ε = 2.9, ε = 3.4, and ε = 3.9, respectively, at different incident beam frequencies. (Refer to...) Figure 3 It can be seen that when the frequency of the incident beam is 23.1 GHz and 29.8 GHz, the reflection phase change of the metasurface unit covers 270° as the dielectric constant of the liquid crystal layer 5 changes.

[0048] As can be seen from the above, when liquid crystal layers are used as tunable materials to construct metasurface units, the reflection and / or scattering amplitudes and phases of the metasurface units become continuously tunable, improving the flexibility of adjusting these parameters. Furthermore, due to the low insertion loss of liquid crystals and their high practical applicability, the operating frequency band of metasurface units can reach millimeter-wave and even terahertz bands when using liquid crystals as tunable materials, thus expanding the operating frequency range of metasurface units.

[0049] Based on the above, the metasurface unit disclosed herein possesses the following characteristics:

[0050] Continuously adjustable, which improves the flexibility of adjustment;

[0051] It has a single polarization direction, which can prevent cross-polarization, ensure the reflection quality of the metasurface, and avoid occupying cross-polarization resources;

[0052] Capable of operating at multiple frequencies;

[0053] The operating frequency band can reach the millimeter wave and even the terahertz band, which expands the operating frequency band of the metasurface unit.

[0054] Therefore, this disclosure provides a millimeter-wave single-polarization multi-frequency (e.g., dual-frequency) reflective metasurface unit based on liquid crystal modulation.

[0055] In summary, the metasurface unit provided in this disclosure includes a metal ground layer; a liquid crystal layer disposed on the metal ground layer; and at least one metal patch disposed on the side of the liquid crystal layer away from the metal ground layer, the at least one metal patch being connected to a power supply via a bias line; the at least one metal patch is rectangular, and the long sides of the at least one metal patch extend in the same direction. By ensuring that the long sides of the at least one rectangular metal patch extend in the same direction, the metasurface unit in this disclosure possesses a single polarization direction, preventing cross-polarization, ensuring the reflection quality of the metasurface, and avoiding the occupation of cross-polarization resources. Furthermore, by using at least one rectangular metal patch with different sizes, the metasurface unit in this disclosure possesses multi-frequency operating capability. Simultaneously, by utilizing the liquid crystal layer as a tunable material to construct the metasurface unit, the reflection and / or scattering amplitude and phase of the metasurface unit are continuously adjustable, improving the flexibility of adjusting the reflection and / or scattering amplitude and phase of the metasurface unit. Furthermore, since liquid crystals have low insertion loss and high practical applicability, when using liquid crystals as tunable materials, the operating frequency band of metasurface units can reach the millimeter wave or even terahertz frequency band, thus expanding the operating frequency band of metasurface units.

[0056] Furthermore, it should be noted that the thicknesses of the liquid crystal layer, metal ground layer, metal patch, first substrate, and second substrate in the aforementioned metasurface unit can be adaptively changed. When the thicknesses of the liquid crystal layer, metal ground layer, metal patch, first substrate, and second substrate change, the reflection and / or scattering amplitude and the reflection and / or scattering phase of the metasurface unit will also change accordingly.

[0057] Furthermore, this disclosure also provides a metasurface, comprising: at least one as described above. Figure 1 and Figure 2 The metasurface unit is shown. In one embodiment of this disclosure, the metasurface can be formed by a periodic or aperiodic arrangement of the metasurface units. For example, in one embodiment of this disclosure, the metasurface can be formed by a periodic arrangement of the metasurface units, such as a matrix arrangement. The metasurface can include m×n metasurface units, where m represents rows and n represents columns, and both m and n are positive integers. However, it should be understood that other possible arrangements are also within the scope of this disclosure, and this disclosure does not limit them.

[0058] Furthermore, it should be noted that in one embodiment of this disclosure, the beam reflected and / or projected by the metasurface is formed by the combined action of all or part of the metasurface units. The combined action of all or part of the metasurface units can be understood as the joint reflection and / or scattering of the incident beam by all or part of the metasurface units. Based on this, it can be determined that the beam deflection angle of the reflected and / or scattered beam of the metasurface is mainly related to the reflection and / or scattering amplitude and the reflection and / or scattering phase of all or part of the metasurface units. In other words, the beam deflection angle of the reflected and / or scattered beam of the metasurface is specifically mainly related to the phase period of the metasurface. The phase period of the metasurface can be understood as: by adjusting the dielectric constant of the liquid crystal layer in the metasurface units to different values, the reflection and / or scattering amplitude and the reflection and / or scattering phase of the metasurface units exhibit periodic changes.

[0059] For example, let's illustrate the phase period described above. Assume the metasurface consists of 1×4 metasurface units, namely metasurface unit #a, metasurface unit #b, metasurface unit #c, and metasurface unit #d. When the dielectric constants of metasurface units #a, #b, #c, and #d are adjusted to the first, second, first, and second values, respectively, then all metasurface units periodically take the same dielectric constant at the particle size of two metasurface units. That is, the reflection and / or scattering amplitudes and reflection and / or scattering phases change periodically at the particle size of two metasurface units. Therefore, the phase period of the metasurface is 2. Similarly, when the dielectric constants of metasurface units #a, #b, #c, and #d are all the first value, the phase period of the metasurface is 1. When the dielectric constants of metasurface units #a, #b, #c, and #d are adjusted to the first, second, third, and fourth values, respectively, the phase period of the metasurface is 4.

[0060] As described above, the phase period of the metasurface affects the reflection and / or scattering amplitude and phase of the metasurface units, which in turn affects the reflection and / or scattering beam deflection angle of the metasurface (i.e., the reflection and / or scattering beam deflection angle of the metasurface is related to the phase period of the metasurface). Furthermore, the phase period of the metasurface is related to its dielectric constant. Therefore, by adjusting the dielectric constant of the liquid crystal layer in different metasurface units, the phase period of the metasurface can be adjusted, thereby adjusting the reflection and / or scattering beam deflection angle of the metasurface to achieve different beam adjustment functions. It should be noted that, assuming the dielectric constant of the liquid crystal layer is continuously adjustable, the reflection and / or scattering beam deflection angle of the metasurface should also be continuously adjustable.

[0061] Furthermore, it should be noted that in one embodiment of this disclosure, when adjusting the dielectric constant of the liquid crystal layer in the metasurface unit, the adjustment can be performed at the same column or same row granularity. For example, the phase period of the metasurface can be adjusted by making the dielectric constant of the liquid crystal layer in the same column of metasurface units the same, and by making the dielectric constant of the liquid crystal layer in different columns of metasurface units different or the same; or, the phase period of the metasurface can be adjusted by making the dielectric constant of the liquid crystal layer in the same row of metasurface units the same, and by making the dielectric constant of the liquid crystal layer in different rows of metasurface units different or the same. This can reduce the complexity of the power supply network.

[0062] Based on this, the following section takes incident beam frequencies of 23.1 GHz (low frequency) and 29.8 GHz (high frequency) as examples to introduce the two-dimensional far-field radiation patterns of the metasurface under different phase periods.

[0063] For example, suppose the metasurface comprises m × 16 metasurface units, where the dielectric constant of the liquid crystal layer of each metasurface unit is adjusted at the column level. That is, the dielectric constant of the liquid crystal layer of metasurface units in the same column is the same. Based on this, Figure 4 Two-dimensional far-field radiation patterns of the metasurface under different phase periods when the incident beam frequency is 23.1 GHz; Figure 5 The image shows the two-dimensional far-field radiation pattern of the metasurface under different phase periods when the incident beam frequency is 29.8 GHz.

[0064] in, Figure 4 and Figure 5 In this context, #1 indicates that the phase period of the metasurface unit is arranged according to the sequence 1111111111111111. This arrangement of 1111111111111111 can be understood as follows: the dielectric constant ε of the liquid crystal layer of the metasurface units in the first to sixteenth columns of the metasurface is the same, ε = 2.4, thus the phase period is one. In this disclosure, the metasurface unit with dielectric constant ε = 2.4 can be named metasurface unit 1.

[0065] Figure 4#2 indicates that the phase period of the metasurface units is arranged in the pattern 1234123412341234. This "arrangement in the pattern 1234123412341234" can be understood as follows: the dielectric constant of the liquid crystal layer of the metasurface units in the first, fifth, ninth, and thirteenth columns is the same, ε = 2.4; the dielectric constant of the liquid crystal layer of the metasurface units in the second, sixth, tenth, and fourteenth columns is the same, ε = 2.93; the dielectric constant of the liquid crystal layer of the metasurface units in the third, seventh, eleventh, and fifteenth columns is the same, ε = 3.18; and the dielectric constant of the liquid crystal layer of the metasurface units in the fourth, eighth, twelfth, and sixteenth columns is the same, ε = 3.8. Therefore, the phase period is four. In this disclosure, the metasurface unit with dielectric constant ε = 2.4 can be named metasurface unit 1, the metasurface unit with dielectric constant ε = 2.93 can be named metasurface unit 2, the metasurface unit with dielectric constant ε = 3.18 can be named metasurface unit 3, and the metasurface unit with dielectric constant ε = 3.8 can be named metasurface unit 4.

[0066] Figure 5 #2 indicates that the phase period of the metasurface units is arranged in the pattern 1234123412341234. This "arrangement in the pattern 1234123412341234" can be understood as follows: the dielectric constant of the liquid crystal layer of the metasurface units in the first, fifth, ninth, and thirteenth columns is the same, ε = 2.4; the dielectric constant of the liquid crystal layer of the metasurface units in the second, sixth, tenth, and fourteenth columns is the same, ε = 2.72; the dielectric constant of the liquid crystal layer of the metasurface units in the third, seventh, eleventh, and fifteenth columns is the same, ε = 2.88; and the dielectric constant of the liquid crystal layer of the metasurface units in the fourth, eighth, twelfth, and sixteenth columns is the same, ε = 3.5. The phase period is also four. In this disclosure, the metasurface unit with dielectric constant ε = 2.4 can be named metasurface unit 1, the metasurface unit with dielectric constant ε = 2.88 can be named metasurface unit 2, the metasurface unit with dielectric constant ε = 3.18 can be named metasurface unit 3, and the metasurface unit with dielectric constant ε = 3.5 can be named metasurface unit 4.

[0067] as well as, Figure 4 and Figure 5In the diagram, #3 indicates that the phase period of the metasurface unit is arranged in the pattern 1122334411223344, which has a phase period of eight. #4 indicates that the phase period of the metasurface unit is arranged in the pattern 1112223334441112, which has a phase period of twelve. #5 indicates that the phase period of the metasurface unit is arranged in the pattern 4321432143214321, which has a phase period of four. #6 indicates that the phase period of the metasurface unit is arranged in the pattern 4433221144332211, which has a phase period of eight. #7 indicates that the phase period of the metasurface unit is arranged in the pattern 2111444333222111, which has a phase period of twelve. The principles behind the above arrangements of "arranged according to 1122334411223344", "arranged according to 1112223334441112", "arranged according to 4321432143214321", "arranged according to 4433221144332211", and "arranged according to 2111444333222111" are similar to those of the aforementioned arrangements of "arranged according to 1111111111111111" and "arranged according to 1234123412341234", and will not be elaborated upon here.

[0068] as well as, Figure 4 and Figure 5 In this context, "Theta" indicates the deflection angle of the reflected beam from the metasurface. Figure 4 and Figure 5 In this context, "Normalized Amplitude" refers to the normalized amplitude of the reflected beam from the metasurface.

[0069] Then by Figure 4 It can be seen that at a low frequency of 23.1 GHz, the reflected beam deflection angle of the metasurface with phase period #2 is 14°, and that of the metasurface with phase period #5 is -14°; the reflected beam deflection angle of the metasurface with phase period #3 is 23°, and that of the metasurface with phase period #6 is -23°; and, reference... Figure 4 and Figure 5 It can be seen that at the low frequency of 23.1 GHz, the beam scans to ±14°, ±23°, and ±50°, respectively, and at the high frequency of 29.8 GHz, the beam scans to ±11.6°, ±17°, and ±36.5°, respectively. At both frequency points, the metasurface achieves beam scanning functionality.

[0070] In summary, this disclosure provides a simple, low-profile, dual-frequency reflective metasurface suitable for the millimeter-wave band. This disclosure constructs a liquid crystal-based reflective metasurface. Previously, diode-loaded metasurfaces could only operate in the lower microwave bands, but by using liquid crystal as the tunable material, the metasurface's operating frequency can reach the millimeter-wave and even terahertz bands. This disclosure expands the operating frequency band of metasurfaces. This disclosure constructs a reflective metasurface based on a dual-pattern structure, where two patches of different sizes operate in one operating frequency band, creating a metasurface with dual-frequency capability. The liquid crystal-based reflective metasurface of this disclosure has continuously adjustable characteristics. By changing the voltage values ​​applied across the liquid crystal layer, continuous adjustment of the cell state is achieved, improving the flexibility of adjustment.

[0071] Those skilled in the art will also understand that the various illustrative logical blocks and steps listed in the embodiments of this application can be implemented by electronic hardware, computer software, or a combination of both. Whether such functionality is implemented through hardware or software depends on the specific application and the overall system design requirements. Those skilled in the art can implement the described functionality using various methods for each specific application, but such implementation should not be construed as exceeding the scope of protection of the embodiments of this application.

[0072] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer programs. When the computer program is loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer program can be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another. For example, the computer program can be transferred from one website, computer, server, or data center to another via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available media may be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., high-density digital video discs (DVDs)), or semiconductor media (e.g., solid-state disks (SSDs)).

[0073] Those skilled in the art will understand that the various numerical designations such as "first," "second," etc., involved in this application are merely for the convenience of description and are not intended to limit the scope of the embodiments of this application, nor do they indicate the order of sequence.

[0074] At least one in this application can also be described as one or more, and multiple can be two, three, four or more, and this application does not impose any limitation. In the embodiments of this application, for a technical feature, the technical features in that technical feature are distinguished by "first", "second", "third", "A", "B", "C" and "D", and there is no order or size among the technical features described by "first", "second", "third", "A", "B", "C" and "D".

[0075] The correspondences shown in the tables of this application can be configured or predefined. The values ​​of the information in each table are merely examples and can be configured to other values; this application is not limited to these values. When configuring the correspondences between information and parameters, it is not necessarily required to configure all the correspondences shown in each table. For example, the correspondences shown in some rows of the tables in this application may not be configured. Furthermore, appropriate modifications and adjustments can be made based on the above tables, such as splitting, merging, etc. The names of the parameters shown in the headings of the above tables can also use other names that the communication device can understand, and the values ​​or representations of the parameters can also be other values ​​or representations that the communication device can understand. In the implementation of the above tables, other data structures can also be used, such as arrays, queues, containers, stacks, linear lists, pointers, linked lists, trees, graphs, structures, classes, heaps, hash tables, or hash tables, etc.

[0076] The term "predefined" in this application can be understood as definition, pre-defined, stored, pre-stored, pre-negotiated, pre-configured, solidified, or pre-burned.

[0077] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0078] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0079] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A metasurface unit, characterized in that, include: Metallic strata; A liquid crystal layer, wherein the liquid crystal layer is disposed on the metal ground layer; At least two metal patches are disposed on the side of the liquid crystal layer away from the metal ground layer, and the at least two metal patches are connected to a power supply via a bias line; The at least two metal patches include a first metal patch and a second metal patch. Both the first metal patch and the second metal patch are rectangular metal patches with a longer side than a shorter side, and the extension direction of the longer side of the first metal patch is the same as the extension direction of the longer side of the second metal patch. The first metal patch and the second metal patch are arranged side by side along a direction that intersects the direction of the long side extension, and the length of the long side of the first metal patch is different from that of the second metal patch, so that the first metal patch and the second metal patch correspond to different operating frequency bands respectively. The first metal patch is used to reflect and / or scatter incident beams whose frequencies belong to its corresponding operating frequency band, and the second metal patch is used to reflect and / or scatter incident beams whose frequencies belong to its corresponding operating frequency band. The extension direction of the long side of the first metal patch and the second metal patch is related to the polarization direction when reflecting and / or scattering the beam. The first metal patch and the second metal patch are used to form a single-polarization dual-frequency metasurface unit. The reflection and / or scattering amplitude and the reflection and / or scattering phase of the metasurface unit are continuously adjustable through the liquid crystal layer. Specifically, the phase period of the metasurface is adjusted by adjusting the dielectric constant of the liquid crystal layer in the metasurface unit, thereby adjusting the reflection and / or scattering beam deflection angle of the metasurface so that the reflection and / or scattering beam deflection angle of the metasurface is continuously adjustable.

2. The metasurface unit as described in claim 1, characterized in that, The metallic layer and the at least two metallic patches are used as reflectors and / or scatterers of the metasurface unit to reflect and / or scatter the incident beam.

3. The metasurface unit as described in claim 1, characterized in that, Different metal patches have different lengths; and / or Different metal patches have different widths; and / or Different metal patches have different areas.

4. The metasurface unit as described in claim 1, characterized in that, The reflection and / or scattering amplitude and phase of the metasurface unit for the incident beam are related to the dielectric constant of the liquid crystal layer, which is related to the voltage of the power supply. The metasurface unit is used to: adjust the dielectric constant of the liquid crystal layer by adjusting the voltage of the power supply, thereby adjusting the reflection and / or scattering amplitude and reflection and / or scattering phase of the metasurface unit for the incident beam.

5. The metasurface unit as described in claim 4, characterized in that, The metal ground layer is used as the negative electrode of the DC bias voltage, and at least two metal patches are used as the positive electrode of the DC bias voltage. The voltage of the power supply is used to adjust the voltage drop across the liquid crystal layer to adjust the dielectric constant of the liquid crystal layer, thereby continuously adjusting the reflection and / or scattering amplitude and reflection and / or scattering phase of the metasurface unit for the incident beam.

6. The metasurface unit as described in claim 1, characterized in that, The metasurface unit also includes: A first substrate is disposed on the side of the metal ground layer away from the liquid crystal layer; The second substrate is disposed on the side of the at least two metal patches away from the liquid crystal layer.

7. The metasurface unit as described in claim 6, characterized in that, The first substrate and the second substrate are made of glass.

8. The metasurface unit as described in claim 6, characterized in that, The reflection and / or scattering amplitude and phase of the metasurface unit vary with the thickness of any one of the liquid crystal layer, the metal ground layer, the metal patch, the first substrate, and the second substrate.

9. A metasurface, characterized in that, include: At least one metasurface unit as described in any one of claims 1-8, wherein the metasurface is formed by a periodic or aperiodic arrangement of the metasurface units.

10. The metasurface as described in claim 9, characterized in that, At least one metasurface unit is arranged in a matrix.

11. The metasurface as described in claim 9 or 10, characterized in that, The reflection and / or scattering beam deflection angle of the metasurface is continuously adjustable; The reflection and / or scattering beam deflection angle of the metasurface is related to the phase period of the metasurface, and the phase period of the metasurface is related to the dielectric constant of the liquid crystal layer in each metasurface unit of the metasurface. The metasurface is used to: adjust the phase period of the metasurface by adjusting the dielectric constant of the liquid crystal layer in different metasurface units, thereby adjusting the reflection and / or scattering beam deflection angle of the metasurface.

12. The metasurface as claimed in claim 11, characterized in that, The metasurface is also used to: adjust the phase period of the metasurface by adjusting the dielectric constant of the liquid crystal layer in the same column or row of the metasurface unit to be the same, and adjusting the dielectric constant of the liquid crystal layer in different rows or columns of the metasurface unit to be different or the same.

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