A liquid crystal metasurface unit with fast response and a wide reflection phase regulation range

Abstract

A liquid crystal metasurface unit with fast response and a wide reflection phase regulation range, comprising 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 stacked in sequence from top to bottom; the upper and lower metal layers respectively include a plurality of metal patches and DC bias lines, wherein the metal patches include liquid crystal regulation metal patches, the liquid crystal regulation metal patches of the upper metal layer and the liquid crystal regulation metal patches of the lower metal layer are overlapped up and down, forming a capacitive effect with the middle liquid crystal layer, the DC bias lines are respectively electrically connected to the metal patches, and are used to apply a voltage to regulate the dielectric constant of the liquid crystal layer through the liquid crystal regulation metal patches, and finally change the reflection phase of the metasurface unit; 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 to achieve a wide reflection phase regulation range of the liquid crystal metasurface unit.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication, and particularly to a liquid crystal metasurface unit with fast response and a wide reflection phase regulation range. Background Art

[0002] Reflective array antennas have attracted great interest due to their low cost, ease of construction, and ability to electronically reconfigure beams. Reflective array antennas can also perform beam scanning, and thus are widely used in satellite communication, radar, and imaging applications. The phase shift function of each unit is a key issue for reflective array antennas, especially when beam control can be achieved using control elements or tunable materials. Common control elements are varactor diodes, p-i-n diodes, and microelectromechanical system switches, and the physical structure or resonant frequency of the elements can be regulated by voltage. However, the parasitic effects of diodes cannot be ignored in frequency bands above 10 GHz. In addition, the reflection phase can also 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, ease of integration, or continuous phase tunability. In addition, compared with arrays relying on other tunable material systems, liquid crystal materials can operate in a wider frequency range with lower power consumption, and are also compatible with modern industrial-grade display manufacturing processes, enabling large-scale production.

[0004] Most of the liquid crystal-based reflective surface array units developed so far are made with relatively thick liquid crystal layers, such as 50 μm, 30 μm, etc. This usually results in greater reflection loss and response time; in addition, the reflection phase regulation 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 art section is only for understanding the background of the present application, and thus may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0006] The main objective of the present invention is to solve the problems existing in the above background art, and to provide a liquid crystal metasurface unit with fast response and a wide reflection phase regulation range.

[0007] To achieve the above objective, the present invention adopts the following technical solutions:

[0008] A liquid crystal metasurface unit with fast response and a wide reflection phase regulation range, comprising a top dielectric layer, an upper metal layer, a liquid crystal layer, a lower metal layer, a lower dielectric layer, and a bottom floor metal layer stacked in sequence from top to bottom; the upper metal layer and the lower metal layer respectively include a plurality of metal patches and DC bias lines, wherein the metal patches include liquid crystal regulation metal patches, the liquid crystal regulation metal patches of the upper metal layer and the liquid crystal regulation metal patches of the lower metal layer are overlapped up and down, forming a capacitance effect with the middle liquid crystal layer, and the DC bias lines are respectively electrically connected to the metal patches for applying a 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 shift structures, and the phase regulation effects of the plurality of resonant phase shift structures are superimposed on each other to achieve the wide reflection phase regulation range of the liquid crystal metasurface unit.

[0009] Further, the upper metal layer includes an upper DC bias line, a first upper liquid crystal regulation metal patch, and a second upper liquid crystal regulation metal patch; the lower metal layer includes a lower DC bias line, a first lower liquid crystal regulation metal patch, and a second lower liquid crystal regulation metal patch; the first upper liquid crystal regulation metal patch and the first lower liquid crystal regulation metal patch are overlapped up and down, forming a first capacitance effect with the middle liquid crystal layer; the second upper liquid crystal regulation metal patch and the second lower liquid crystal regulation metal patch are overlapped up and down, forming a second capacitance effect with the middle liquid crystal layer.

[0010] Further, the upper metal layer further includes a first upper L-shaped metal patch and a second upper L-shaped metal patch; the lower metal layer further 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 form a first resonant phase shift 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 form a second resonant phase shift structure, and the phase shift effects of the first resonant phase shift structure and the second resonant phase shift structure are superimposed on each other to achieve the wide reflection phase regulation range of the liquid crystal metasurface unit.

[0011] Further, the thickness range of the liquid crystal layer is 5 - 20 microns.

[0012] Further, 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.

[0013] Furthermore, both the top dielectric layer and the bottom dielectric layer are glass substrates.

[0014] Furthermore, the upper DC bias line is connected to the region with the lowest electric field amplitude distribution in the first upper L-shaped metal patch and the second upper L-shaped metal patch when a linearly polarized wave is incident; the lower DC bias line is connected to the region with the lowest electric field amplitude distribution in the first lower L-shaped metal patch and the second lower L-shaped metal patch when a linearly polarized wave is incident.

[0015] Furthermore, there are two resonance peaks respectively generated by the first resonance phase shift structure and the second resonance phase shift structure. The frequencies of the two resonance peaks are close but not equal. When the relative dielectric constant of the liquid crystal layer changes, the frequencies of the two resonance peaks shift to lower frequencies simultaneously, resulting in a change in the reflection phase.

[0016] Furthermore, the reflection phase regulation range of the liquid crystal metasurface unit exceeds 270 degrees, and the reflection loss is less than 2 dB.

[0017] The present invention has the following beneficial effects:

[0018] The present invention provides a liquid crystal metasurface unit with fast response and a wide reflection phase regulation range. By designing multiple resonant phase-shifting structures within a single liquid crystal metasurface unit, the superposition effect of these structures is utilized to achieve a significantly broadened reflection phase regulation range, breaking through the phase regulation limit of only about 180 degrees for traditional liquid crystal metasurface units, thereby significantly enhancing the practicality of the liquid crystal metasurface array. At the same time, further, such resonant phase-shifting structures can regulate the reflection phase using a liquid crystal layer with a thickness of 5 - 20 micrometers. Compared with the thicker liquid crystal layers commonly used in the prior art, the response speed is greatly improved and the reflection loss is reduced, effectively solving the problems of long response time and large loss brought by the traditional thick liquid crystal layer design. In addition, the liquid crystal-regulated metal patches of the upper metal layer and the liquid crystal-regulated metal patches of the lower metal layer overlap vertically, forming a capacitance effect with the liquid crystal layer in the middle. A voltage is applied by the DC bias line to regulate the dielectric constant of the liquid crystal layer through the liquid crystal-regulated metal patches, thereby changing the capacitance value in the capacitance effect. This design realizes the precise regulation of the reflection phase, further optimizing the flexibility and precision of phase regulation. Further, by connecting the upper and lower DC bias lines to the regions where the electric field amplitude distribution is small when the linearly polarized wave is incident, the potential influence of the external voltage controller on the reflection phase of the metasurface is eliminated, thereby further optimizing the stability and precision of phase regulation. These innovative designs not only endow the liquid crystal metasurface unit of the present invention with fast response and wide reflection phase regulation capabilities, but also maintain compatibility with modern industrial-grade display manufacturing processes, achieving advantages such as cost-effectiveness, easy integration, and continuously adjustable phase, providing a high-performance, low-power consumption, and mass-producible solution for the application of reflection array antennas in the microwave and millimeter-wave frequency bands, and being particularly suitable for fields such as satellite communication, radar, and imaging.

[0019] Other beneficial effects in the embodiments of the present invention will be further described below. Brief Description of the Drawings

[0020] Figure 1 Shows the overall structural schematic diagram of a liquid crystal metasurface unit according to an embodiment of the present invention.

[0021] Figure 2 Shows the top view of the metal pattern of a liquid crystal metasurface unit according to an embodiment of the present invention.

[0022] Figure 3 Shows the reflection amplitude of a liquid crystal metasurface unit with fast response and a wide reflection phase regulation range according to an embodiment of the present invention.

[0023] Figure 4 Shows the reflection phase of a liquid crystal metasurface unit with fast response and a wide reflection phase regulation range according to an embodiment of the present invention.

[0024] Figure 5Shows the electric field distribution corresponding to the resonant frequency of the first resonant phase-shifting structure of a fast-response liquid crystal metasurface unit with a wide reflection phase regulation range according to an embodiment of the present invention.

[0025] Figure 6 Shows the electric field distribution corresponding to the resonant frequency of the second resonant phase-shifting structure of a fast-response liquid crystal metasurface unit with a wide reflection phase regulation range according to an embodiment of the present invention. Detailed implementation manners

[0026] The following makes a detailed description of the implementation manners of the present invention. It should be emphasized that the following description is merely exemplary and not intended to limit the scope of the present invention and its applications.

[0027] Refer to Figures 1 to 2 , an embodiment of the present invention provides a fast-response liquid crystal metasurface unit with a wide reflection phase regulation range, which includes a top dielectric layer 101, an upper metal layer, a liquid crystal layer 107, a lower metal layer, a lower dielectric layer 113, and a bottom ground 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 DC bias lines, wherein the metal patches include liquid crystal modulation metal patches, the liquid crystal modulation metal patches of the upper metal layer and the liquid crystal modulation metal patches of the lower metal layer are overlapped up and down, and form a capacitance effect with the middle liquid crystal layer 107, and the DC bias lines are respectively electrically connected to the metal patches and are used to apply a voltage to regulate the dielectric constant of the liquid crystal layer 107 through the liquid crystal modulation 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 to achieve the wide reflection phase regulation range of the liquid crystal metasurface unit.

[0028] In the liquid crystal metasurface unit of the present invention, a voltage is applied through the DC bias line to regulate the dielectric constant of the liquid crystal layer, change the capacitance value, and achieve precise regulation of the reflection phase. By designing a plurality of resonant phase-shifting structures in a single liquid crystal metasurface unit, the present invention can achieve a wide reflection phase regulation range of more than 270 degrees by using their superimposed effects, breaking through the phase regulation limit of about 180 degrees of traditional liquid crystal metasurface units. 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 bands such as satellite communication, radar, and imaging.

[0029] Such as 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 and the first lower liquid crystal regulation metal patch 112 overlap vertically, forming a first capacitance effect with the intermediate liquid crystal layer 107; the second upper liquid crystal regulation metal patch 104 and the second lower liquid crystal regulation metal patch 109 overlap vertically, forming a second capacitance effect with the intermediate liquid crystal layer 107.

[0030] As Figure 1 shown, in some embodiments, the upper metal layer further includes a first upper L-shaped metal patch 102 and a second upper L-shaped metal patch 105; the lower metal layer further 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 form a first resonant phase shift 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 form a second resonant phase shift structure, and the phase shift effects of the first resonant phase shift structure and the second resonant phase shift structure are superimposed on each other to achieve a wide reflection phase regulation range of the liquid crystal metasurface unit.

[0031] In a preferred embodiment, the thickness range of the liquid crystal layer 107 is 5 - 20 microns.

[0032] Two resonant phase shift structures are formed within a single liquid crystal metasurface unit. Through the superimposed effect of the two resonant phase shift structures, a wider reflection phase adjustment range is achieved. Further, such a resonant phase shift structure can regulate the reflection phase using a liquid crystal layer with a thickness of 5 - 20 microns, which improves the regulation response speed compared with a thicker liquid crystal layer and has lower reflection loss.

[0033] 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.

[0034] In some embodiments, both the top dielectric layer 101 and the lower dielectric layer 113 are glass substrates.

[0035] In a preferred embodiment, the upper DC bias line 106 is connected to the regions 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 regions 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.

[0036] The upper DC bias line is connected to the locations with relatively smaller electric field amplitude distributions in the first upper L-shaped metal patch and the second upper metal patch when a linearly polarized wave is incident; the lower DC bias line is connected to the locations with relatively smaller electric field amplitude distributions in the first lower L-shaped metal patch and the second lower metal patch when a linearly polarized wave is incident, eliminating the influence of the external voltage controller on the reflection phase of the metasurface.

[0037] In some embodiments, the liquid crystal metasurface unit has 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 permittivity of the liquid crystal layer 107 changes, the frequencies of the two resonance peaks shift towards the low frequency simultaneously.

[0038] The present invention can provide a liquid crystal metasurface unit with a thin liquid crystal layer and a reflection phase regulation range greater than 180 degrees. Preferably, the reflection phase regulation range of the liquid crystal metasurface unit exceeds 270 degrees, and the reflection loss is less than 2 dB.

[0039] The following further describes specific embodiments of the present invention.

[0040] A liquid crystal metasurface unit with fast response and wide phase regulation range includes a top dielectric layer 101, an upper metal layer, a liquid crystal layer 107, a lower metal layer, a lower dielectric layer 113, and a bottom ground 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 regulating metal patch, and the first lower liquid crystal regulating metal patch are equivalent to constituting a first resonant element; the second upper L-shaped metal patch, the second lower L-shaped metal patch, the second upper liquid crystal regulating metal patch, and the second lower liquid crystal regulating metal patch are equivalent to constituting a second resonant element. The phase regulation effects of the first resonant element and the second resonant element are superimposed to achieve a wide reflection phase regulation range of the liquid crystal metasurface unit. The reflection phase of the liquid crystal metasurface is controlled by applying voltages through the upper DC bias line and the lower DC bias line.

[0041] Specifically, as Figure 1As shown, the liquid crystal metasurface unit is preferably a square with a side length of 5.5 mm, and includes a top dielectric layer 101, an upper metal layer, a liquid crystal layer 107, a lower metal layer, a lower dielectric layer 113, and a bottom floor metal layer 114, which are 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 modulation metal patch 103, and a second upper liquid crystal modulation 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 modulation metal patch 112, and a second lower liquid crystal modulation metal patch 109.

[0042] The above-mentioned upper DC bias line 106 forms electrical connections with the first upper L-shaped metal patch 102, the second upper L-shaped metal patch 105, the first upper liquid crystal modulation metal patch 103, and the second upper liquid crystal modulation metal patch 104; the lower DC bias line 111 forms electrical connections with the first lower L-shaped metal patch 108, the second lower L-shaped metal patch 110, the first lower liquid crystal modulation metal patch 112, and the second lower liquid crystal modulation metal patch 109.

[0043] The thicknesses of the above-mentioned top dielectric layer 101 and the lower dielectric layer 113 are preferably 0.5 mm, and the relative dielectric constants are preferably 3.75; the thickness of the above-mentioned 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.

[0044] The above-mentioned first upper liquid crystal modulation metal patch 103 and the first lower liquid crystal modulation metal patch 112 overlap vertically, forming a capacitance effect with the middle liquid crystal layer 107; the second upper liquid crystal modulation metal patch 104 and the second lower liquid crystal modulation metal patch 109 overlap vertically, forming a capacitance effect with the middle liquid crystal layer 107. The DC voltage controls the dielectric constant of the liquid crystal layer 107 through the first upper liquid crystal modulation metal patch 103 and the second upper liquid crystal modulation metal patch 104 connected by the upper DC bias line 106, and the first lower liquid crystal modulation metal patch 112 and the second lower liquid crystal modulation metal patch 109 connected by the lower DC bias line 111, thereby changing the capacitance value in the capacitance effect, and finally realizing the reflection phase modulation of the metasurface unit.

[0045] As Figure 3 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 frequencies of the two resonance peaks are close but not equal. When the relative dielectric constant of the liquid crystal layer changes, the two resonance peaks shift to lower frequencies simultaneously, resulting in a change in the reflection phase.

[0046] As Figure 3 andFigure 4 As shown, 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 exceeds 270 degrees at most. The reflection loss of the liquid crystal metasurface unit has been below 2 dB. It can meet the design of the 2-bit phase-encoded metasurface.

[0047] As Figure 5 shown, at the resonant 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; As Figure 6 shown, at the resonant frequency corresponding to the second resonant phase-shifting structure of the liquid crystal metasurface unit, the electric field is mainly distributed on the second 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 second resonant phase-shifting structure is relatively low.

[0048] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those skilled in the technical field to which the present invention belongs, without departing from the concept of the present invention, several equivalent substitutions or obvious modifications can be made, and as long as the performance or use is the same, they should all 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 to achieve a wide reflection phase regulation range of the liquid crystal metasurface unit; wherein the upper metal layer comprises an upper DC bias line, a first upper liquid crystal regulation metal patch, and a second upper liquid crystal regulation metal patch; the lower metal layer comprises a lower DC bias line, a first lower liquid crystal regulation metal patch, and a second lower liquid crystal regulation metal patch; the first upper liquid crystal regulation metal patch overlaps with the first lower liquid crystal regulation metal patch up and down, forming a first capacitance effect with the middle liquid crystal layer; the second upper liquid crystal regulation metal patch overlaps with the second lower liquid crystal regulation metal patch up and down, forming a second capacitance effect with the middle liquid crystal layer; 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.

2. The liquid crystal metasurface unit according to claim 1, characterized in that: The thickness of the liquid crystal layer is in the range of 5-20 microns.

3. The liquid crystal metasurface unit according to claim 1, 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.

4. The liquid crystal metasurface unit according to claim 1, characterized in that: The top dielectric plate layer and the bottom dielectric plate layer are both glass substrates.

5. The liquid crystal metasurface unit according to claim 1, 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.

6. The liquid crystal metasurface unit according to claim 1, 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.

7. The liquid crystal metasurface unit according to claim 1, 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.

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