Quick-response liquid crystal metasurface unit with wide reflection phase regulation and control range

Abstract

The invention discloses a quick-response liquid crystal metasurface unit with a wide reflection phase regulation and control range. The quick-response liquid crystal metasurface unit comprises a top dielectric plate layer, an upper metal layer, a liquid crystal layer, a lower metal layer, a lower dielectric plate layer and a bottom floor metal layer which are sequentially stacked from top to bottom, the upper metal layer and the lower metal layer respectively comprise a plurality of metal patches and direct-current bias lines, the metal patches comprise liquid crystal regulation and control metal patches, and the liquid crystal regulation and control metal patches of the upper metal layer and the liquid crystal regulation and control metal patches of the lower metal layer are overlapped up and down and form a capacitance effect with the liquid crystal layer in the middle. The direct current bias lines are electrically connected with the metal patches respectively and used for applying voltage to regulate and control the dielectric constant of the liquid crystal layer through the liquid crystal regulation and control metal patches, and finally the reflection phase of the metasurface unit is changed; the metal patches form a plurality of resonant phase-shifting structures, and the phase regulation and control effects of the resonant phase-shifting structures are mutually superposed, so that the wide reflection phase regulation and control range of the liquid crystal metasurface unit is realized.

Description

Technical Field

[0001] The present invention relates to the field of wireless communications, and in particular to a fast-response liquid crystal metasurface unit with a wide reflection phase control range. Background Art

[0002] Reflectarray antennas have attracted great interest due to their low cost, ease of construction, and ability to electronically reconfigure the beam. Reflectarray antennas are also capable of beam scanning and are therefore widely used in satellite communications, radar, and imaging applications. The phase shift function of each element is a key issue for reflectarray antennas, especially since control elements or tunable materials can be used to steer the beam. Common control elements are varactor diodes, pin diodes, and microelectromechanical system switches, where the physical structure or resonant frequency of the element can be regulated by voltage. However, the parasitic effects of the diodes are not negligible in frequency bands above 10 GHz. In addition, the reflection phase can be changed by using tunable materials such as ferrites and liquid crystals.

[0003] Reflective arrays based on liquid crystal metasurfaces are an attractive option for microwave and millimeter wave applications. They have advantages such as cost-effectiveness, easy integration or continuous phase tunability. In addition, compared with arrays relying on other tunable material systems, liquid crystal materials can operate over a wider frequency range and consume less power, while being compatible with modern industrial-grade display manufacturing processes and enabling large-scale production.

[0004] Most of the liquid crystal-based reflective surface array units to date are made of thicker liquid crystal layers, such as 50um, 30um, etc. This usually leads to greater reflection loss and response time; in addition, the reflection phase adjustment range of most liquid crystal metasurface units is about 180 degrees, which greatly reduces the practicality of liquid crystal metasurface arrays.

[0005] It should be noted that the information disclosed in the above background technology section is only used for understanding the background of the present application, and therefore may include information that does not constitute prior art known to ordinary technicians in the field. Summary of the invention

[0006] The main purpose of the present invention is to solve the problems existing in the above-mentioned background technology and to provide a fast-responding liquid crystal metasurface unit with a wide reflection phase control range.

[0007] To achieve the above object, the present invention adopts the following technical solutions: A fast-response liquid crystal metasurface unit with a wide reflection phase regulation range comprises a top dielectric plate layer, an upper metal layer, a liquid crystal layer, a lower metal layer, a lower dielectric plate layer and a bottom floor metal layer which are sequentially stacked from top to bottom; the upper metal layer and the lower metal layer respectively comprise a plurality of metal patches and a DC bias line, wherein the metal patches comprise liquid crystal regulation metal patches, the liquid crystal regulation metal patches of the upper metal layer overlap with the liquid crystal regulation metal patches of the lower metal layer, and form a capacitance effect with the liquid crystal layer in the middle, the DC bias lines are respectively electrically connected to the metal patches, and are used to apply voltage to regulate the dielectric constant of the liquid crystal layer through the liquid crystal regulation metal patches, thereby changing the capacitance value in the capacitance effect; the metal patches form a plurality of resonant phase-shifting structures, and the phase regulation effects of the plurality of resonant phase-shifting structures are superimposed on each other, so as to realize a wide reflection phase regulation range of the liquid crystal metasurface unit.

[0008] Furthermore, the upper metal layer includes an upper DC bias line, a first upper liquid crystal control metal patch and a second upper liquid crystal control metal patch; the lower metal layer includes a lower DC bias line, a first lower liquid crystal control metal patch and a second lower liquid crystal control metal patch; the first upper liquid crystal control metal patch overlaps with the first lower liquid crystal control metal patch up and down, forming a first capacitance effect with the middle liquid crystal layer; the second upper liquid crystal control metal patch overlaps with the second lower liquid crystal control metal patch up and down, forming a second capacitance effect with the middle liquid crystal layer.

[0009] Furthermore, the upper metal layer also includes a first upper L-shaped metal patch and a second upper L-shaped metal patch; the lower metal layer also includes a first lower L-shaped metal patch and a second lower L-shaped metal patch; the first upper L-shaped metal patch, the first lower L-shaped metal patch, the first upper liquid crystal regulation metal patch and the first lower liquid crystal regulation metal patch constitute a first resonant phase-shifting structure; the second upper L-shaped metal patch, the second lower L-shaped metal patch, the second upper liquid crystal regulation metal patch and the second lower liquid crystal regulation metal patch constitute a second resonant phase-shifting structure, and the phase shifting effects of the first resonant phase-shifting structure and the second resonant phase-shifting structure are superimposed on each other to achieve a wide reflection phase regulation range of the liquid crystal metasurface unit.

[0010] Furthermore, the thickness of the liquid crystal layer is in the range of 5-20 micrometers.

[0011] Furthermore, the side length d of the liquid crystal metasurface unit satisfies 0.25λt≤d≤0.5λt, wherein λt=c / ft, ft is the center frequency of the working frequency band, c is the speed of light in vacuum, and λt is the wavelength corresponding to the center frequency of the working frequency band.

[0012] Furthermore, the top dielectric layer and the bottom dielectric layer are both glass substrates.

[0013] Furthermore, the upper DC bias line is connected to the area where the electric field amplitude distribution is lowest in the first upper L-shaped metal patch and the second upper L-shaped metal patch when a linear polarized wave is incident; the lower DC bias line is connected to the area where the electric field amplitude distribution is lowest in the first lower L-shaped metal patch and the second lower L-shaped metal patch when a linear polarized wave is incident.

[0014] Furthermore, there are two resonance peaks respectively generated by the first resonance phase-shifting structure and the second resonance phase-shifting structure, the frequencies of the two resonance peaks are close but not equal, and when the relative dielectric constant of the liquid crystal layer changes, the two resonance peak frequencies simultaneously move toward low frequencies, resulting in a change in the reflection phase.

[0015] Furthermore, the reflection phase control range of the liquid crystal metasurface unit exceeds 270 degrees, and the reflection loss is less than 2dB.

[0016] The present invention has the following beneficial effects: The present invention provides a fast-response liquid crystal metasurface unit with a wide reflection phase control range. By designing multiple resonant phase-shifting structures in a single liquid crystal metasurface unit, the superposition effect of these structures is used to achieve a significantly broadened reflection phase control range, breaking through the phase control limit of only about 180 degrees of the traditional liquid crystal metasurface unit, thereby significantly improving the practicality of the liquid crystal metasurface array. At the same time, further, this resonant phase-shifting structure can use a liquid crystal layer with a thickness of 5-20 microns to control the reflection phase. Compared with the thicker liquid crystal layer commonly used in the prior art, it greatly improves the response speed and reduces the reflection loss, effectively solving the problems of long response time and large loss caused by the traditional thick liquid crystal layer design. In addition, the liquid crystal control metal patch of the upper metal layer overlaps the liquid crystal control metal patch of the lower metal layer, forming a capacitive effect with the liquid crystal layer in the middle, and the DC bias line applies a voltage to control the dielectric constant of the liquid crystal layer through the liquid crystal control metal patch, thereby changing the capacitance value in the capacitive effect. This design realizes precise control of the reflection phase and further optimizes the flexibility and accuracy of phase control. Furthermore, by connecting the upper and lower DC bias lines in an area where the electric field amplitude distribution is small when a linearly polarized wave is incident, the potential influence of the external voltage controller on the metasurface reflection phase is eliminated, thereby further optimizing the stability and accuracy of the phase control. These innovative designs not only enable the liquid crystal metasurface unit of the present invention to have fast response and wide reflection phase control capabilities, but also maintain compatibility with modern industrial-grade display manufacturing processes, achieving the advantages of cost-effectiveness, easy integration, and continuously adjustable phase, providing a high-performance, low-power, and mass-producible solution for reflective array antenna applications in microwave and millimeter-wave frequency bands, particularly suitable for satellite communications, radar, and imaging.

[0017] Other beneficial effects of the embodiments of the present invention will be further described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of the overall structure of a liquid crystal supersurface unit according to an embodiment of the present invention is shown.

[0019] Figure 2 A top view of a metal pattern of a liquid crystal supersurface unit according to an embodiment of the present invention is shown.

[0020] Figure 3 The reflection amplitude of a liquid crystal metasurface unit with fast response and wide reflection phase control range according to an embodiment of the present invention is shown.

[0021] Figure 4 The reflection phase of a liquid crystal metasurface unit with a fast response and a wide reflection phase control range according to an embodiment of the present invention is shown.

[0022] Figure 5The electric field distribution corresponding to the resonant frequency of the first resonant phase-shifting structure of a liquid crystal metasurface unit with a fast response and a wide reflection phase control range in an embodiment of the present invention is shown.

[0023] Figure 6 The electric field distribution corresponding to the resonant frequency of the second resonant phase-shifting structure of a liquid crystal metasurface unit with a fast response and a wide reflection phase control range in an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0024] The following is a detailed description of the embodiments of the present invention. It should be emphasized that the following description is only exemplary and is not intended to limit the scope and application of the present invention.

[0025] See also Figure 1 to Figure 2 The embodiment of the present invention provides a fast-response liquid crystal metasurface unit with a wide reflection phase control range, comprising a top dielectric plate layer 101, an upper metal layer, a liquid crystal layer 107, a lower metal layer, a lower dielectric plate layer 113 and a bottom floor metal layer 114 stacked in sequence from top to bottom; the upper metal layer and the lower metal layer respectively include a plurality of metal patches and a DC bias line, wherein the metal patches include liquid crystal control metal patches, the liquid crystal control metal patches of the upper metal layer overlap with the liquid crystal control metal patches of the lower metal layer, and form a capacitance effect with the liquid crystal layer 107 in the middle, the DC bias lines are respectively electrically connected to the metal patches, and are used to apply voltage to control the dielectric constant of the liquid crystal layer 107 through the liquid crystal control metal patches, thereby changing the capacitance value in the capacitance effect; the metal patches form a plurality of resonant phase-shifting structures, and the phase control effects of the plurality of resonant phase-shifting structures are superimposed on each other, so as to realize a wide reflection phase control range of the liquid crystal metasurface unit.

[0026] In the liquid crystal metasurface unit of the present invention, the dielectric constant of the liquid crystal layer is regulated by applying a voltage through a DC bias line, the capacitance value is changed, and the precise regulation of the reflection phase is achieved. The present invention designs multiple resonant phase-shifting structures in a single liquid crystal metasurface unit, and utilizes their superposition effect to achieve a wide reflection phase regulation range of more than 270 degrees, breaking through the phase regulation limit of about 180 degrees of the traditional liquid crystal metasurface unit. A thin liquid crystal layer can be used to significantly improve the response speed and reduce the reflection loss. The present invention has the characteristics of fast response, wide phase regulation range, low loss and easy integration, and is suitable for applications in microwave and millimeter wave frequency bands such as satellite communications, radar and imaging.

[0027] like Figure 1As shown, in some embodiments, the upper metal layer includes an upper DC bias line 106, a first upper liquid crystal regulation metal patch 103 and a second upper liquid crystal regulation metal patch 104; the lower metal layer includes a lower DC bias line 111, a first lower liquid crystal regulation metal patch 112 and a second lower liquid crystal regulation metal patch 109; the first upper liquid crystal regulation metal patch 103 overlaps with the first lower liquid crystal regulation metal patch 112 up and down, forming a first capacitance effect with the middle liquid crystal layer 107; the second upper liquid crystal regulation metal patch 104 overlaps with the second lower liquid crystal regulation metal patch 109 up and down, forming a second capacitance effect with the middle liquid crystal layer 107.

[0028] like Figure 1 As shown, in some embodiments, the upper metal layer also includes a first upper L-shaped metal patch 102 and a second upper L-shaped metal patch 105; the lower metal layer also includes a first lower L-shaped metal patch 108 and a second lower L-shaped metal patch 110; the first upper L-shaped metal patch 102, the first lower L-shaped metal patch 108, the first upper liquid crystal regulation metal patch 103 and the first lower liquid crystal regulation metal patch 112 constitute a first resonant phase-shifting structure; the second upper L-shaped metal patch 105, the second lower L-shaped metal patch 110, the second upper liquid crystal regulation metal patch 104 and the second lower liquid crystal regulation metal patch 109 constitute a second resonant phase-shifting structure, and the phase shifting effects of the first resonant phase-shifting structure and the second resonant phase-shifting structure are superimposed on each other to achieve a wide reflection phase regulation range of the liquid crystal metasurface unit.

[0029] In a preferred embodiment, the thickness of the liquid crystal layer 107 is in the range of 5-20 microns.

[0030] Two resonant phase-shifting structures are formed in a single liquid crystal metasurface unit. Through the superposition of the two resonant phase-shifting structures, a wider reflection phase adjustment range is achieved. Furthermore, this resonant phase-shifting structure can utilize a liquid crystal layer with a thickness of 5-20 microns to regulate the reflection phase, which improves the response speed of regulation compared with a thicker liquid crystal layer and has lower reflection loss.

[0031] In a preferred embodiment, the side length d of the liquid crystal metasurface unit satisfies 0.25λt≤d≤0.5λt, where λt=c / ft, ft is the center frequency of the working frequency band, c is the speed of light in vacuum, and λt is the wavelength corresponding to the center frequency of the working frequency band.

[0032] In some embodiments, the top dielectric layer 101 and the bottom dielectric layer 113 are both glass substrates.

[0033] In a preferred embodiment, the upper DC bias line 106 is connected to the area with the lowest electric field amplitude distribution in the first upper L-shaped metal patch 102 and the second upper L-shaped metal patch 105; the lower DC bias line 111 is connected to the area with the lowest electric field amplitude distribution in the first lower L-shaped metal patch 108 and the second lower L-shaped metal patch 110.

[0034] The upper DC bias line is connected to the location where the electric field amplitude distribution is smaller in the first upper L-shaped metal patch and the second upper metal patch when a linear polarization wave is incident; the lower DC bias line is connected to the location where the electric field amplitude distribution is smaller in the first lower L-shaped metal patch and the second lower metal patch when a linear polarization wave is incident, thereby eliminating the influence of an external voltage controller on the reflection phase of the metasurface.

[0035] In some embodiments, the liquid crystal metasurface unit has two resonance peaks generated by the first resonant phase-shifting structure and the second resonant phase-shifting structure, respectively. The frequencies of the two resonance peaks are close but not equal, and when the relative dielectric constant of the liquid crystal layer 107 changes, the two resonance peak frequencies move toward low frequencies at the same time.

[0036] The present invention can provide a liquid crystal metasurface unit with a thin liquid crystal layer and a reflection phase control range greater than 180 degrees. Preferably, the reflection phase control range of the liquid crystal metasurface unit exceeds 270 degrees, and the reflection loss is less than 2dB.

[0037] Specific embodiments of the present invention are further described below.

[0038] A liquid crystal metasurface unit with fast response and wide phase control range includes a top dielectric plate layer 101, an upper metal layer, a liquid crystal layer 107, a lower metal layer, a lower dielectric plate layer 113 and a bottom floor metal layer 114 arranged in sequence from top to bottom. Among them, the first upper L-shaped metal patch, the first lower L-shaped metal patch, the first upper liquid crystal control metal patch and the first lower liquid crystal control metal patch are equivalent to forming a first resonant element; the second upper L-shaped metal patch, the second lower L-shaped metal patch, the second upper liquid crystal control metal patch and the second lower liquid crystal control metal patch are equivalent to forming a second resonant element. The phase control effects of the first resonant element and the second resonant element are superimposed to achieve a wide reflection phase control range of the liquid crystal metasurface unit. The reflection phase of the liquid crystal metasurface is controlled by applying voltage to the upper DC bias line and the lower DC bias line.

[0039] Specific as Figure 1As shown, the liquid crystal metasurface unit is preferably a square with a side length of 5.5 mm, including a top dielectric plate layer 101, an upper metal layer, a liquid crystal layer 107, a lower metal layer, a lower dielectric plate layer 113 and a bottom floor metal layer 114 arranged in sequence from top to bottom. The upper metal layer includes a first upper L-shaped metal patch 102, a second upper L-shaped metal patch 105, an upper DC bias line 106, a first upper liquid crystal control metal patch 103, and a second upper liquid crystal control metal patch 104; the lower metal layer includes a first lower L-shaped metal patch 108, a second lower L-shaped metal patch 110, a lower DC bias line 111, a first lower liquid crystal control metal patch 112, and a second lower liquid crystal control metal patch 109.

[0040] The above-mentioned upper DC bias line 106 is electrically connected to the first upper L-shaped metal patch 102, the second upper L-shaped metal patch 105, the first upper liquid crystal regulation metal patch 103, and the second upper liquid crystal regulation metal patch 104; the lower DC bias line 111 is electrically connected to the first lower L-shaped metal patch 108, the second lower L-shaped metal patch 110, the first lower liquid crystal regulation metal patch 112, and the second lower liquid crystal regulation metal patch 109.

[0041] The thickness of the top dielectric layer 101 and the bottom dielectric layer 113 is preferably 0.5 mm, and the relative dielectric constant is preferably 3.75; the thickness of the liquid crystal layer 107 is 10 mm, and the relative dielectric constant of the liquid crystal material varies in the range of 2.55-3.75.

[0042] The first upper liquid crystal control metal patch 103 and the first lower liquid crystal control metal patch 112 overlap up and down, forming a capacitance effect with the middle liquid crystal layer 107; the second upper liquid crystal control metal patch 104 and the second lower liquid crystal control metal patch 109 overlap up and down, forming a capacitance effect with the middle liquid crystal layer 107. The first upper liquid crystal control metal patch 103 and the second upper liquid crystal control metal patch 104 connected by the upper DC bias line 106 and the first lower liquid crystal control metal patch 112 and the second lower liquid crystal control metal patch 109 connected by the lower DC bias line 111 are used to control the dielectric constant of the liquid crystal layer 107, thereby changing the capacitance value in the capacitance effect, and finally realizing the reflection phase control of the metasurface unit.

[0043] like Figure 3 As shown, the metasurface unit has two resonance peaks, which are generated by the first resonance phase shift structure and the second resonance phase shift structure respectively. The two resonance peaks have close but unequal frequencies. When the relative dielectric constant of the liquid crystal layer changes, the two resonance peaks move to low frequencies at the same time, resulting in a change in the reflection phase.

[0044] like Figure 3 and Figure 4 As shown in the figure, when the relative dielectric constant of the liquid crystal material changes from 2.55 to 3.75, the reflection phase of the liquid crystal metasurface changes continuously and the maximum exceeds 270 degrees. The reflection loss of the liquid crystal metasurface unit is always below 2dB. This can meet the design of a 2-bit phase-encoded metasurface.

[0045] like Figure 5 As shown, at the resonance frequency corresponding to the first resonant phase-shifting structure of the liquid crystal metasurface unit, the electric field is mainly distributed on the first resonant phase-shifting structure, and the electric field amplitude at the connection between the upper DC bias line 106 and the lower DC bias line 111 and the first resonant phase-shifting structure is relatively low; Figure 6 As shown, at the resonance frequency corresponding to the second resonant phase-shift structure of the liquid crystal metasurface unit, the electric field is mainly distributed on the second resonant phase-shift structure, and the electric field amplitude at the connection between the upper DC bias line 106 and the lower DC bias line 111 and the second resonant phase-shift structure is relatively low.

[0046] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art of the present invention, several equivalent substitutions or obvious variations can be made without departing from the concept of the present invention, and the performance or use is the same, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A fast-response liquid crystal metasurface unit with a wide reflection phase control range, characterized in that: It includes a top dielectric plate layer, an upper metal layer, a liquid crystal layer, a lower metal layer, a lower dielectric plate layer and a bottom floor metal layer which are stacked in sequence from top to bottom; the upper metal layer and the lower metal layer respectively include a plurality of metal patches and a DC bias line, wherein the metal patches include liquid crystal control metal patches, the liquid crystal control metal patches of the upper metal layer overlap with the liquid crystal control metal patches of the lower metal layer, and form a capacitance effect with the liquid crystal layer in the middle, and the DC bias lines are respectively electrically connected to the metal patches, and are used to apply voltage to control the dielectric constant of the liquid crystal layer through the liquid crystal control metal patches, thereby changing the capacitance value in the capacitance effect; The metal patches form a plurality of resonant phase-shifting structures, and the phase regulation effects of the plurality of resonant phase-shifting structures are superimposed on each other, thereby realizing a wide reflection phase regulation range of the liquid crystal metasurface unit.

2. The liquid crystal metasurface unit according to claim 1, characterized in that: The upper metal layer includes an upper DC bias line, a first upper liquid crystal control metal patch and a second upper liquid crystal control metal patch; the lower metal layer includes a lower DC bias line, a first lower liquid crystal control metal patch and a second lower liquid crystal control metal patch; the first upper liquid crystal control metal patch overlaps with the first lower liquid crystal control metal patch up and down, forming a first capacitance effect with the middle liquid crystal layer; the second upper liquid crystal control metal patch overlaps with the second lower liquid crystal control metal patch up and down, forming a second capacitance effect with the middle liquid crystal layer.

3. The liquid crystal metasurface unit according to claim 2, characterized in that: The upper metal layer also includes a first upper L-shaped metal patch and a second upper L-shaped metal patch; the lower metal layer also includes a first lower L-shaped metal patch and a second lower L-shaped metal patch; the first upper L-shaped metal patch, the first lower L-shaped metal patch, the first upper liquid crystal regulation metal patch and the first lower liquid crystal regulation metal patch constitute a first resonant phase-shifting structure; the second upper L-shaped metal patch, the second lower L-shaped metal patch, the second upper liquid crystal regulation metal patch and the second lower liquid crystal regulation metal patch constitute a second resonant phase-shifting structure, and the phase shifting effects of the first resonant phase-shifting structure and the second resonant phase-shifting structure are superimposed on each other to achieve a wide reflection phase regulation range of the liquid crystal metasurface unit.

4. The liquid crystal metasurface unit according to any one of claims 1 to 3, characterized in that: The thickness of the liquid crystal layer is in the range of 5-20 microns.

5. The liquid crystal supersurface unit according to any one of claims 1 to 3, characterized in that: The side length d of the liquid crystal metasurface unit satisfies 0.25λ t ≤d≤0.5λ t , where λ t =c / f t , f t is the center frequency of the working frequency band, c is the speed of light in vacuum, λ t It is the wavelength corresponding to the center frequency of the working frequency band.

6. The liquid crystal metasurface unit according to any one of claims 1 to 3, characterized in that: The top dielectric plate layer and the bottom dielectric plate layer are both glass substrates.

7. The liquid crystal metasurface unit according to claim 3, characterized in that: The upper DC bias line is connected to the area where the electric field amplitude distribution is lowest in the first upper L-shaped metal patch and the second upper L-shaped metal patch when a linear polarization wave is incident; the lower DC bias line is connected to the area where the electric field amplitude distribution is lowest in the first lower L-shaped metal patch and the second lower L-shaped metal patch when a linear polarization wave is incident.

8. The liquid crystal metasurface unit according to claim 3, characterized in that: There are two resonance peaks respectively generated by the first resonance phase-shifting structure and the second resonance phase-shifting structure, the frequencies of the two resonance peaks are close but not equal, and when the relative dielectric constant of the liquid crystal layer changes, the two resonance peak frequencies simultaneously move toward low frequencies, resulting in a change in the reflection phase.

9. The liquid crystal metasurface unit according to claim 3, characterized in that: The reflection phase control range of the liquid crystal metasurface unit exceeds 270 degrees, and the reflection loss is less than 2dB.

Images