Liquid crystal reconfigurable intelligent surface device

Abstract

Devices and methods for liquid crystal (LC) reconfigurable intelligent surface (RIS) substrate designs and materials are described. In some examples, an LC RIS device includes a first metal layer and a second metal layer, where each of the first metal layer and the second metal layer is deposited within a glass substrate. The first metal layer has a first dimension and the second metal layer has a second dimension, where the first dimension is different from the second dimension. Further, the device includes an LC layer disposed between the first metal layer and the second metal layer. In some examples, the first metal layer includes a plurality of columns, where each of the plurality of columns includes a first plurality of LC active layers. In some examples, the second metal layer includes a plurality of rows, where each of the plurality of rows includes a second plurality of LC active layers.

Description

Technical Field

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority to U.S. Provisional Application No. 63 / 405,008, filed on September 9, 2022, which is incorporated herein by reference in its entirety.

[0003] The present disclosure relates generally to reconfigurable intelligent surface (RIS) devices, and more particularly to liquid crystal RIS diode devices. Background Art

[0004] Millimeter-wave (mm-Wave) frequency bands are increasingly used for various applications, such as for communications, including 5G and 6G wireless communications. Millimeter-wave communications can provide benefits over previous communication technologies, including higher communication speeds, lower communication latency, and greater capacity. For example, millimeter-wave communications can operate in the 30 to 300 GHz frequency range. However, there are some challenges in sending and receiving wireless signals in the millimeter-wave frequency band due to reasons such as propagation loss, penetration loss, and reflection loss, which may reduce the corresponding budget of the link.

[0005] To compensate for these challenges, some systems employ high-gain phased array antennas. However, the additional gain provided by high-gain phased array antennas can have drawbacks. For example, as the number of array elements increases, the antenna can become saturated. In addition, high-gain phased array antennas increase system losses and provide limited gain when used in devices (e.g., mobile devices) that have limited space to accommodate the antenna.

[0006] Recently, the use of reconfigurable smart surface (RIS) devices has been proposed to improve the propagation channel conditions between base stations and mobile devices in, for example, 5G and New Radio (NR) communication systems. RIS can include the use of sub-wavelength resonators that adaptively reflect, transmit, absorb, and convert the polarization of incident waves with low power consumption. For example, active RIS is a millimeter wave device that can control the reflection of signals in a desired direction. In addition, RIS can be manufactured at a low cost because the component costs are generally low. Summary of the invention

[0007] Embodiments disclosed herein generally relate to liquid crystal (LC) reconfigurable smart surface (RIS) substrate devices. In some embodiments, the device may include a layered orthogonal voltage bias structure capable of providing two-dimensional electromagnetic waves. In some embodiments, the device allows for better control of the active region where the LC molecules switch (e.g., tilt) due to the bias. For example, the device may include an LC cell comprising an LC layer, a first electrode, and a second electrode (e.g., a ground electrode), wherein the LC layer rotates the LC only in the desired active region based on the design of the LC cell. Among other advantages, the RIS device may operate more efficiently than conventional devices. In addition, the RIS device may be used in a variety of applications. For example, the RIS device may be used in wireless communication systems, such as 5G, NR, and 6G wireless communication systems (e.g., millimeter wave band networks) to provide two-dimensional beamforming, such as beam forward and backward. In addition, the manufacturing cost of the RIS device may be lower than that of conventional RIS devices. A person of ordinary skill in the art to which the present invention belongs who benefits from these disclosures may also recognize other benefits.

[0008] In some examples, the unit cell device includes parallel metal layers deposited within a glass material, and an LC layer disposed between the metal layers. The metal layers may be in the form of a repeating pattern (e.g., a repeating array). The unit cell device may resonate near an operating frequency band. The metal layers may serve as bias lines, where the alignment of the LC within the LC layers is caused by the bias between the metal layers. Thus, the LC alignment may vary based on the bias, and thus the dielectric constant (e.g., ε) that may be in the range of 1 to 100 for the LC material may vary. This variable ε may allow for various frequency responses of the unit cell device.

[0009] For example, the unit cell device may include a first metal layer (e.g., a top metal layer), the first metal layer and the second metal layer (e.g., a bottom metal layer) are laterally offset, and the first metal layer and the second metal layer are deposited in a glass material. The first metal layer may include a plurality of columns, wherein each column includes a first plurality of LC active layers. In addition, the columns may be electrically disconnected from each other. For example, each of the columns may be electrically connected to a voltage source (e.g., a bias source). The second metal layer may include a plurality of rows, wherein each row includes a second plurality of LC active layers. Each row may be electrically disconnected from each other. In some instances, each of the first plurality of LC active layers is laterally offset from a corresponding one of the second plurality of LC active layers. The unit cell device also includes an LC layer between the first metal layer and the second metal layer.

[0010] In some cases, the rows of the second metal layer are electrically connected to a ground (eg, a common ground). In other cases, the rows of the second metal layer are electrically connected to a voltage source.

[0011] In some examples, the columns of the first metal layer are electrically connected to ground, and the rows of the second metal layer are electrically connected to a voltage source. In other examples, the columns of the first metal layer are electrically connected to a voltage source, and the rows of the second metal layer are electrically connected to ground. In still other examples, the columns of the first metal layer and the rows of the second metal layer are each electrically connected to a voltage source.

[0012] In some examples, the unit cell device includes parallel metal layers deposited in a glass material, and a liquid crystal (LC) layer disposed between the metal layers. The parallel metal layers can each be used as an electrode. For example, the parallel metal layers can include a first metal layer and a second metal layer, wherein the first metal layer is electrically connected to a voltage source and the second metal layer is electrically connected to ground. In some cases, the first metal layer and the second metal layer have the same size. For example, the first metal layer and the second metal layer can have the same width and length (for example, taking a rectangular shape as an example). In some examples, the size of the first metal layer is larger than the second metal layer. For example, the area of ​​the first metal layer can be a certain percentage (for example, 10%) larger than the second metal layer. In other examples, the size of the first metal layer is smaller than the second metal layer. For example, the area of ​​the first metal layer can be a certain percentage (for example, 10%) smaller than the second metal layer. In some cases, the size of the first metal layer can be the same as the glass material, while the size of the second metal layer is smaller than the glass material.

[0013] In some embodiments, the unit cell device includes a first metal layer and a second metal layer, wherein each of the first metal layer and the second metal layer is deposited within a glass substrate. The first metal layer has a first size, and the second metal layer has a second size, wherein the first size is different from the second size. In addition, the unit cell device includes an LC layer disposed between the first metal layer and the second metal layer.

[0014] In some embodiments, a unit cell device includes a first metal layer and a second metal layer deposited within a glass substrate, wherein the first metal layer and the second metal layer are laterally offset. The first metal layer includes a plurality of columns, wherein each of the plurality of columns includes a first plurality of LC active layers. The second metal layer includes a plurality of rows, wherein each of the plurality of rows includes a second plurality of LC active layers. The unit cell further includes an LC layer deposited between the first metal layer and the second metal layer.

[0015] In some examples, a method (e.g., by an apparatus including one or more processors executing instructions) includes depositing a metal material on a first glass substrate to form a first metal layer having a first size. The method may also include depositing an LC material on the first metal layer to form an LC layer. In addition, the method may also include depositing a metal material on the LC layer to form a second metal layer having a second size, the second size being different from the first size. The method may also include depositing a second glass substrate on the second metal layer.

[0016] In some examples, a method (e.g., by an apparatus including one or more processors executing instructions) includes depositing a metal material on a first glass substrate to form a first metal layer having a first plurality of LC active layers. The method may also include depositing an LC material on the first metal layer to form an LC layer. In addition, the method may also include depositing a metal material on the LC layer to form a second metal layer having a second plurality of LC active layers. The method may also include depositing a second glass substrate on the second metal layer.

[0017] In some embodiments, a non-transitory computer-readable medium stores instructions that, when executed by one or more processors, cause an apparatus to perform a method comprising the steps of depositing a metal material on a first glass substrate to form a first metal layer having a first size. The method may also include depositing an LC material on the first metal layer to form an LC layer. In addition, the method may also include depositing a metal material on the LC layer to form a second metal layer having a second size, the second size being different from the first size. The method may also include depositing a second glass substrate on the second metal layer.

[0018] In some embodiments, a non-transitory computer-readable medium stores instructions that, when executed by one or more processors, cause an apparatus to perform a method comprising the steps of depositing a metal material on a first glass substrate to form a first metal layer having a first plurality of LC active layers. The method may also include depositing an LC material on the first metal layer to form an LC layer. In addition, the method may also include depositing a metal material on the LC layer to form a second metal layer having a second plurality of LC active layers. The method may also include depositing a second glass substrate on the second metal layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above summary of the invention and the following detailed description of illustrative embodiments can be understood in conjunction with the accompanying drawings. The accompanying drawings show some illustrative embodiments discussed herein. As further explained below, the claims are not limited to the illustrative embodiments. For clarity and ease of reading, the accompanying drawings may omit views of certain features.

[0020] Figure 1A and Figure 1B An apparatus according to some examples is illustrated.

[0021] Figure 2A , Figure 2B and Figure 2C Illustrated is the alignment of liquid crystal in a device according to some examples.

[0022] Figure 3 Phase and dielectric constant graphs according to some examples are illustrated.

[0023] Figure 4A, Figure 4B , Figure 5A , Figure 5B , Fig. 6A , Figure 6B , Fig. 7A , Figure 7B Devices and corresponding frequency response graphs according to some examples are illustrated.

[0024] Fig. 8A Graphs illustrate electric field distribution of a device according to some examples.

[0025] Figure 8B Illustration of the switching of liquid crystal in a device according to some examples.

[0026] Fig.9A and Fig. 9B An apparatus according to some examples is illustrated.

[0027] Fig. 9C , Fig.9D , Fig.9E and Fig.9F Various configurations of apparatus according to some examples are illustrated.

[0028] Fig. 10A An apparatus according to some examples is illustrated.

[0029] Fig. 10B and Fig. 10C Tilt angles according to some examples are illustrated.

[0030] Fig.11A , Fig. 11B , Fig. 11C and Fig.11D The apparatus is illustrated in various configurations according to some examples.

[0031] Fig.11E The diagram shows some examples Fig.11A , Fig. 11B , Fig. 11C and Fig.11D The inclination angle of various devices.

[0032] Fig. 12A , Fig. 12B and Fig. 12C The apparatus is illustrated in various configurations according to some examples.

[0033] Fig.13A and Fig. 13B An apparatus according to some examples is illustrated. DETAILED DESCRIPTION

[0034] This application discloses illustrative (i.e., example) embodiments. The disclosure is not limited to the illustrative embodiments. Therefore, many embodiments of the claims will differ from the illustrative embodiments. Various modifications may be made to the claims without departing from the spirit and scope of the disclosure. The claims are intended to cover embodiments with such modifications.

[0035] At times, this application may use directional terms (e.g., front, back, top, bottom, left, right, etc.) to give the reader context when viewing the accompanying drawings. However, the claims are not limited to the orientations shown in the drawings. Any absolute terms (e.g., high, low, etc.) may be understood to disclose corresponding relative terms (e.g., higher, lower, etc.). In addition, although the exemplary examples discussed herein may refer to a reconfigurable smart surface (RIS) device including a liquid crystal (LC) layer, exemplary embodiments may also include other types of suitable semiconductor devices.

[0036] Figure 1A and Figure 1B RIS device 100 is illustrated, such as a LC RIS unit cell. RIS device 100 includes a first glass substrate 102, a second glass substrate 104, a first metal layer 110, a second metal layer 120, and an LC layer 130. The first metal layer 110 includes a plurality of metal columns 112, each metal column 112 including a first plurality of LC active layers 114. Similarly, the second metal layer 120 includes a plurality of metal rows 122, each metal row 122 including a second plurality of LC active layers 124. The first metal layer 110 is laterally offset (i.e., a cell gap) from the second metal layer 120. In some examples, the cell gap is in a range of 3 to 500 microns. In some examples, the cell gap is in a range of 10 to 200 microns. In some examples, the cell gap is in a range of 5 to 200 microns. For example, the first metal layer 110 may be laterally offset and parallel to the second metal layer 120. In addition, the LC layer 130 may be composed of an LC material deposited between the first metal layer 110 and the second metal layer 120. The LC material may include, for example, dual-band LC, cholesteric LC, smectic LC, blue phase LC, ferroelectric LC, nematic LC, discotic LC, thermotropic LC, and lyotropic LC.

[0037] As shown, each of the first plurality of LC active layers 114 may be laterally offset from a corresponding one of the second plurality of LC active layers 124. LC material from the LC layer 130 is deposited between each of the first plurality of LC active layers 114 and a corresponding one of the second plurality of LC active layers 124. Furthermore, each of the plurality of LC active layers 114 and a corresponding one of the second plurality of LC active layers 124 may function as electrodes and provide a bias to the LC material deposited therebetween.

[0038] For example, each of the plurality of metal columns 112 of the first metal layer 110 can be electrically connected to a voltage source (e.g., a DC bias line) to provide a voltage to each of the first plurality of LC active layers 114. In some examples, each of the plurality of metal columns 112 is electrically connected to the same voltage source. In some examples, at least two of the plurality of metal columns 112 are electrically connected to different voltage sources. In this way, each of the plurality of metal columns 112 can provide the same or different voltage at each of the corresponding first plurality of LC active layers 114.

[0039] Similarly, each of the plurality of metal rows 122 of the second metal layer 120 may also be electrically connected to a voltage source, or may be connected to ground. In some examples, each of the plurality of metal rows 122 is electrically connected to the same voltage source or ground. In some examples, at least two of the plurality of metal rows 122 are electrically connected to different voltage sources. In this way, each of the plurality of metal rows 122 may provide the same or different voltage at each of the corresponding second plurality of LC active layers 124.

[0040] The plurality of metal columns 112 of the first metal layer 110 and the plurality of metal rows 122 of the second metal layer 120 provide orthogonal bias lines to corresponding portions of the LC layer 130. In this way, each of the first plurality of LC active layers 114 and a corresponding one of the second plurality of LC active layers 124 can form an LC active region therebetween. For example, each of the first plurality of LC active layers 114 and a corresponding one of the second plurality of LC active layers 124 can provide a bias voltage to the LC material therebetween, thereby causing a corresponding LC shift. By providing varying voltages at the plurality of metal columns 112 of the first metal layer 110 and the plurality of metal rows 122 of the second metal layer 120, a single RIS 100 can provide various voltage differences between the first plurality of LC active layers 114 and a corresponding one of the second plurality of LC active layers 114.

[0041] In some applications, by providing various voltage differences between the first plurality of LC active layers 114 and corresponding ones of the second plurality of LC active layers 124, the RIS device 100 can provide two-dimensional beamforming within a wireless communication system, such as, for example, a 5G, NR, or 6G wireless communication system. In addition, although the RIS device 100 is generally shown as a rectangular unit cell, the RIS device 100 can have any suitable shape, such as a circular, elliptical, pentagonal, hexagonal, etc. In addition, as Figure 1B As illustrated, RIS device 100 may optionally include a third metal layer 140 electrically connected to ground.

[0042] Figure 2A , Figure 2B and Figure 2CThree modes of operation are illustrated, where the alignment of the LC shift is shifted based on a bias voltage provided across one of the first plurality of LC active layers 114 and a corresponding one of the second plurality of LC active layers 124. Due to the alignment shift, the dielectric constant of the liquid crystal changes. In this example, a voltage source 204 is electrically connected to each of the LC active layers 114, 124 to provide a bias voltage across the LC layer 130. Figure 2A In , no voltage is applied (eg, voltage source 204 is off), so LC 201 is parallel to LC active layers 114, 124 (eg, 0 tilt). Figure 2B In , the voltage source 204 is turned on and a first voltage is provided between the LC active layers 114, 124. In response, at least some of the LCs 201 tilt (eg, to a corresponding first angle). Figure 2C In some cases, the voltage provided by the voltage source 204 is increased to provide a second voltage between the LC active layers 114, 124. In response, at least some of the LCs 201 are further tilted (e.g., to a corresponding second angle greater than the first angle). In some cases, the distance from one of the first plurality of LC active layers 114 to a corresponding one of the second plurality of LC active layers 124 (e.g., Figure 2C In some embodiments, the distance may be in the range of 10 to 200 microns. In some embodiments, the distance may be in the range of 5 to 200 microns.

[0043] Figure 3 A graph 300 is included that illustrates various bias voltages 310 (eg, Figure 2A , Figure 2B and Figure 2C 308 of the LC active layer 114, 124 of the embodiment of the present invention. The calculated ε value represents the effective ε of the LC calculated by numerical methods based on its molecular structure when the bias is changed. The approximate value illustrates how the calculated ε value changes as a function of the bias. In general, as the bias 310 increases, the approximate and calculated ε 302, 304 increase, while the approximate and calculated phases 306, 308 decrease. As can be seen from the graph 300, at a higher bias 310 (e.g., above 25V), the approximate and calculated ε 302, 304 increase at a lower rate than the lower bias 310 (e.g., equal to or lower than 25V). Similarly, at a higher bias 310, the approximate and calculated phases 306, 308 decrease at a lower rate than the lower bias 310.

[0044] Figure 4ARIS device 400 is illustrated, and includes a first glass substrate 402, a second glass substrate 404, a first metal layer 410, a second metal layer 420, and an LC layer 430. The first metal layer 410 includes a plurality of metal columns 412, each of which includes a first plurality of LC active layers 414. Similarly, the second metal layer 420 includes a plurality of metal rows 422, each of which includes a second plurality of LC active layers 424. Although five metal columns 412 and five metal rows 422 are illustrated, RIS device 400 may have any suitable number of metal columns 412 (e.g., 1, 3, 7, 10, etc.) and any suitable number of metal rows 422 (e.g., 1, 3, 7, 10, etc.). In some examples, the number of metal columns 412 is the same as the number of metal rows 422. In some examples, the number of metal columns 412 is different from the number of metal rows 422.

[0045] Return to reference Figure 4A , the first metal layer 110 is laterally offset from the second metal layer 420. For example, the first metal layer 410 can be laterally offset and parallel to the second metal layer 420. In addition, the LC layer 430 can be composed of an LC material deposited between the first metal layer 410 and the second metal layer 420.

[0046] In this example, each of the plurality of metal columns 412 of the first metal layer 410 is electrically connected to a corresponding voltage source 415. For example, the first metal column 412A is electrically connected to the first voltage source 415A. In addition, the second metal column 412B is electrically connected to the second voltage source 415B, the third metal column 412C is electrically connected to the third voltage source 415C, the fourth metal column 412D is electrically connected to the fourth voltage source 415D, and the fifth metal column 412E is electrically connected to the fifth voltage source 415E. Each of the voltage sources 415A, 415B, 415C, 415D, and 415E can provide the same or different voltage as the other voltage sources. In addition, in this example, each of the plurality of metal rows 422 of the second metal layer 420 is electrically connected to the ground 417. In this way, each of the first plurality of LC active layers 414 and a corresponding one of the second plurality of LC active layers 424 provides a bias on a corresponding portion (eg, LC active region) of the LC layer 430, wherein the bias may be different across the plurality of metal columns 412 of the first metal layer 410.

[0047] Figure 4BA graph 450 is illustrated identifying a frequency response for each of a plurality of metal columns 412 corresponding to a first metal layer 410. For example, assume that each of voltage sources 415A, 415B, 415C, 415D, and 415E provides a corresponding voltage that is different from one another. Thus, first metal column 412A may enable a first frequency response 452A, while second metal column 412B may enable a second frequency response 452B. Furthermore, third metal column 412C may enable a third frequency response 452C, fourth metal column 412D may enable a fourth frequency response 452D, and fifth metal column 412E may enable a fifth frequency response 452E. Thus, RIS device 400 may provide different frequency responses across a plurality of metal columns 412 (e.g., different frequency responses along the "Y" direction of RIS device 400).

[0048] Figure 5A RIS device 400 is illustrated with different bias voltages across multiple metal rows 422 of second metal layer 420. In this example, each of multiple metal columns 412 of first metal layer 410 is electrically connected to ground 417. However, multiple metal rows 422 of second metal layer 420 are electrically connected to corresponding voltage sources 415. For example, first metal row 422A is electrically connected to first voltage source 415A. In addition, second metal row 422B is electrically connected to second voltage source 415A, third metal row 422C is electrically connected to third voltage source 415C, fourth metal row 422D is electrically connected to fourth voltage source 415D, and fifth metal row 422E is electrically connected to fifth voltage source 415E. Each of first voltage sources 415A, 415B, 415C, 415D, and 415E can provide the same or different voltages as the other voltage sources. In this way, each of the first plurality of LC active layers 414 and a corresponding one of the second plurality of LC active layers 424 provide a bias on a corresponding portion (eg, LC active region) of the LC layer 430, wherein the bias across the plurality of metal rows 422 of the second metal layer 420 may be different.

[0049] Figure 5BA graph 460 is illustrated that identifies a frequency response corresponding to each of a plurality of metal rows 422 of a second metal layer 420. For example, assume that each of voltage sources 415A, 415B, 415C, 415D, and 415E provides a corresponding voltage that is different from one another. Thus, first metal row 422A may enable a first frequency response 462A, while second metal row 422B may enable a second frequency response 462B. Furthermore, third metal row 422C may enable a third frequency response 462C, fourth metal row 422D may enable a fourth frequency response 462D, and fifth metal row 422E may enable a fifth frequency response 462E. Thus, RIS device 400 may provide different frequency responses across a plurality of metal rows 422 (e.g., different frequency responses along the "X" direction of RIS device 400).

[0050] Fig. 6A The RIS device 400 is illustrated with different bias voltages between a plurality of metal columns 412 of a first metal layer 410 and a plurality of metal rows 422 of a second metal layer 420. Specifically, in this example, the plurality of metal rows 422 of the second metal layer 420 are electrically connected to corresponding voltage sources 415, as described with respect to FIG. Figure 5A As described. In addition, each of the plurality of metal columns 412 of the first metal layer 410 is electrically connected to a corresponding voltage source 475. For example, the first metal column 412A is electrically connected to the sixth voltage source 475A. In addition, the second metal column 412B is electrically connected to the seventh voltage source 475B, the third metal column 412C is electrically connected to the eighth voltage source 475C, the fourth metal column 412D is electrically connected to the ninth voltage source 475D, and the fifth metal column 412E is electrically connected to the tenth voltage source 475E. Each of the voltage sources 415A, 415B, 415C, 415D, 415E, 475A, 415B, 415C, 415D, and 415E can provide the same or different voltages as the other voltage sources.

[0051] In this way, each of the first plurality of LC active layers 414 and a corresponding one of the second plurality of LC active layers 424 provide a bias voltage on a corresponding portion (e.g., LC active region) of the LC layer 430, wherein the bias voltage across the plurality of metal columns 412 of the first metal layer 410 and across the plurality of metal rows 422 of the second metal layer 420 may be different. For example, each of the first plurality of LC active layers 414 and a corresponding one of the second plurality of LC active layers 424 may provide a bias voltage across a corresponding portion of the LC layer 430, thereby allowing a frequency response that may be different from that enabled at other of the first plurality of LC active layers 414 and a corresponding one of the second plurality of LC active layers 424. In some examples, the same bias voltage may be provided by two or more of the first plurality of LC active layers 414 and a corresponding one of the second plurality of LC active layers 424. In some examples, each of the first plurality of LC active layers 414 and a corresponding one of the second plurality of LC active layers 424 provide a bias voltage for the LC active layer that is different from each other.

[0052] Figure 6B A graph 470 is illustrated identifying frequency responses corresponding to each of the first plurality of LC active layers 414 and a corresponding one of the second plurality of LC active layers 424. For example, in this example, the RIS device 400 can provide up to twenty-five varying frequency responses. Thus, in this example, the RIS device 400 can provide different frequency responses across the plurality of metal columns 412 (e.g., different frequency responses along the "Y" direction of the RIS device 400) and across the plurality of metal rows 422 (e.g., different frequency responses along the "X" direction of the RIS device 400).

[0053] Fig. 7A and Figure 7B RIS device 700 is illustrated, and includes a first glass substrate 702, a second glass substrate 704, a first metal layer 709, a second metal layer 719, and an LC layer 730. The first metal layer 709 includes a first metal column 710 and a second metal column 712. Similarly, the second metal layer 719 includes a first metal row 720 and a second metal row 722. The first metal layer 709 is laterally offset from the second metal layer 719. For example, the first metal layer 709 can be laterally offset and parallel to the second metal layer 719. In addition, the LC layer 730 can be composed of an LC material deposited between the first metal layer 709 and the second metal layer 719.

[0054] In this example, first voltage source 715A is electrically connected to first metal column 710 of first metal layer 709, while second voltage source 715B is electrically connected to second metal column 712 of first metal layer 709. Similarly, third voltage source 725A is electrically connected to first metal row 720 of second metal layer 719, while fourth voltage source 725B is electrically connected to second metal row 722 of second metal layer 719.

[0055] In this example, the RIS device 700 can provide up to four bias voltages on corresponding portions of the LC layer 730. For example, a first bias voltage (e.g., based on a voltage provided by the voltage sources 715A and 725A) can be provided between the first metal column 710 of the first metal layer 709 and the first metal row 720 of the second metal layer 719. In addition, a second bias voltage (e.g., based on a voltage provided by the voltage sources 715A and 725B) can be provided between the first metal column 710 of the first metal layer 709 and the second metal row 722 of the second metal layer 719. Similarly, a third bias voltage (e.g., based on a voltage provided by the voltage sources 715B and 725A) can be provided between the second metal column 712 of the first metal layer 709 and the first metal row 720 of the second metal layer 719. In addition, a fourth bias voltage (e.g., based on a voltage provided by the voltage sources 715B and 725B) can be provided between the second metal column 712 of the first metal layer 709 and the second metal row 722 of the second metal layer 719. Thus, in this example, RIS device 700 can provide up to four different frequency responses based on four bias voltages.

[0056] Although as shown, each of the first metal column 710, the second metal column 712, the first metal row 720, and the second metal row 722 is electrically connected to a corresponding voltage source, in some examples, one or more of the first metal column 710, the second metal column 712, the first metal row 720, and the second metal row 722 is electrically connected to ground. Figure 7B As shown, the RIS device 700 may optionally include a third metal layer 740 electrically connected to ground.

[0057] Fig. 8A and Figure 8B The diagram illustrates that the LC can be aligned (e.g., "tilted") when under bias and in an "active region" (e.g., LC switching region), but may not be aligned when not in the "active region". An active RIS device can include a frequency selective surface (FSS) layer and an LC layer for phase tuning. The FSS layer reflects the desired frequency band, and the LC layer can be used to control beam steering. In some embodiments, the LC of the LC layer is rotated in a unit cell in the FSS region of the RIS device based on the design of the ground electrode of the LC unit cell.

[0058] For example, Fig. 8A FIG. 8 is an image 800 illustrating electric field distribution on a passive frequency selective surface (FSS) device 802 under incident radio frequency (RF) waves. The electric field distribution mainly occurs across unit cells 854 of the passive FSS device 802. Figure 8B The RIS device 850 is illustrated, and includes a glass substrate 852, a unit cell 854 (e.g., a voltage can be applied to the unit cell through electrodes), and LCs 860, 862. Although the LC 862 is within the LC active region of the unit cell 854, the LC 860 is not within the LC active region of the unit cell 854. The first figure (e.g., the left figure) shows the RIS device 850 in a bias "OFF" state (e.g., no voltage is applied), while the second figure (e.g., the right figure) shows the RIS device 850 in a bias "ON" state (e.g., a voltage is applied). As shown, when the bias is "OFF", the LC 862 is in a misaligned state, and when the bias is "ON", the LC 862 is in an aligned state. However, whether the bias is "ON" or "OFF", the LC 860 remains in a misaligned state.

[0059] Fig.9A and Fig. 9B A device 900 (eg, an LC unit cell) is illustrated, wherein Fig.9A A three-dimensional view of the device 900 is shown, and Fig. 9B 900. The device 900 includes a first bias electrode 902, a second bias electrode 904, and an LC layer 910 disposed between the first electrode 902 and the second electrode 904. The device 900 may further include a first glass substrate 920 (e.g., a top glass substrate) and a second glass substrate 922 (e.g., a bottom glass substrate), such as Fig. 9B As shown. The first glass substrate 920 and the second glass substrate 922 may include (e.g., surround) the first electrode 902 and the second electrode 904. In some examples, the size (e.g., area) of the first electrode 902 and the second electrode 904 may be the same, or substantially the same (e.g., within 1%). In some examples, the size of the first electrode 902 and the second electrode 904 may be different.

[0060] For example, Fig. 9C , Fig.9D , Fig.9E and Fig.9F Various configurations of the apparatus 900 are illustrated. Fig. 9CIn the embodiment, the size of the second electrode 904 is the same as (or substantially the same as) the size of the second glass substrate 922. In this example, the size of the first electrode 904 can be smaller than that of the second electrode 904, or substantially the same as that of the second electrode 904.

[0061] exist Fig.9D In the embodiment of the present invention, the size of the second electrode 904 is larger than the size of the first electrode 902. For example, the size of the second electrode 904 may be 10% larger than the size of the first electrode 902. In some examples, the size of the second electrode 904 may be in the range of 5% to 25% larger than the size of the first electrode 902. In some examples, the size of the second electrode 904 may be in the range of 25% to 50% larger than the size of the first electrode 902. In addition, the size of the second electrode 904 may be the same as the size of the second glass substrate 922 or smaller than the size of the second glass substrate 922.

[0062] exist Fig.9E In the embodiment, the size of the second electrode 904 is the same as or substantially the same as the size of the first electrode 902. In addition, the size of each of the second electrode 904 and the first electrode 902 is the same as or smaller than the size of the second glass substrate 922. In some examples, the size of each of the second electrode 904 and the first electrode 902 is in the range of 30% to 70% of the size of the second glass substrate 922.

[0063] exist Fig.9F In the embodiment of the present invention, the size of the second electrode 904 is smaller than the size of the first electrode 902. For example, the size of the second electrode 904 may be 10% smaller than the size of the first electrode 902. In some examples, the size of the second electrode 904 may be in the range of 5% to 25% smaller than the size of the first electrode 902. In some examples, the size of the second electrode 904 may be in the range of 25% to 50% smaller than the size of the first electrode 902. In addition, the size of the first electrode 902 may be the same as or smaller than the size of the second glass substrate 922.

[0064] Despite Fig. 9C , Fig.9D , Fig.9E and Fig.9F Although not shown, the size of the first glass substrate 920 can be the same or substantially the same as the size of the second glass substrate 922. In addition, although the device 900 is illustrated as a cube, other shapes and forms are also contemplated, such as rectangles, prisms, spheres, cones, and cylinders.

[0065] When a bias voltage is applied between the first electrode 902 and the second electrode 904 (for example, Fig. 9C , Fig.9D , Fig.9E and Fig.9F ), at least a portion of the LC within the LC layer 901 is shifted to align. For example, Fig. 10B The tilt angle 1006 of LC 1004 is shown. Initially, without applied bias, the LC may have a tilt angle of, for example, 2 degrees. Once bias is applied, some LCs (e.g., LC 1004) may "tilt" from an initial position (e.g., from two degrees) to a final position (e.g., 90 degrees). The tilt of the LC may depend on the configuration of device 900.

[0066] For example, Fig. 10A A cross-sectional viewpoint 1002 of the device 900 is identified, wherein Fig. 10C A diagram 1010 is shown that identifies the Fig. 9C , Fig.9D , Fig.9E and Fig.9F The tilt angles of the LC within the portion of the LC layer 910 identified by the cross-sectional viewpoint 1002 for various device 900 configurations. The tilt angles correspond to the LC from the first position 950 of the cross-sectional viewpoint 1002 to the final position 952 of the cross-sectional viewpoint 1002. Fig.9F Configurations of the device 900 in which the size of the second electrode 904 is smaller (eg, 10% smaller) than the size of the first electrode 902 do not tilt the LC outside the region of the first electrode 902 as do other device 900 configurations.

[0067] Fig.11A , Fig. 11B , Fig. 11C and Fig.11D The diagram shows the corresponding Fig. 9C , Fig.9D , Fig.9E and Fig.9F Apparatus 1100 configured as described. Fig.11A , Fig. 11B , Fig. 11C and Fig.11D Each of 1100 further illustrates the LC 1101 within the active region 1102 of the device 1100 (eg, the portion of the LC layer between the electrodes), and the LC 1105 outside the active region 1102 . Fig.11A The diagram shows the Fig. 9C The configuration depicted is the LC active region 1102 of the device 1100 (eg, where the size of the second electrode 904 is the same or substantially the same as the size of the second glass substrate 922 and is larger than the size of the first electrode 902). Fig. 11B The diagram shows the Fig.9DThe configuration depicted is the LC active region 1102 of the device 1100 (eg, where the second electrode 904 is larger (eg, 10%) in size than the first electrode 902). Fig. 11C The diagram shows the Fig.9E The configuration depicted is the LC active region 1102 of the device 1100 (where the second electrode 904 is the same or substantially the same size as the first electrode 902). Fig.11D The diagram shows the Fig.9F The configuration depicted is the LC active region 1102 of the device 1100 (eg, where the second electrode 904 is smaller in size (eg, 10%) than the first electrode 902).

[0068] Fig.11A , Fig. 11B and Fig. 11C Also shown are regions 1120 of LC 1105, where the corresponding LC 1105 is aligned outside of the corresponding LC active region 1102 when the corresponding LC active region 1102 is placed under a bias. For example, when a bias is applied to Fig.11A LC active region 1102 (wherein the device 1100 is in Fig. 9C ), the LC 1105 in region 1120 tends to tilt (eg, the tilt angle increases from the initial angle). Similarly, Fig. 11B and Fig. 11C LC 1105 is also identified in region 1120 which tends to tilt when a bias is applied in a corresponding configuration. Fig.11D In the embodiment, when a bias is applied, the LC 1005 outside the LC active region 1102 does not tend to tilt. On the contrary, when a bias is applied, only the LC 1101 inside the LC active region 1102 tends to tilt.

[0069] Fig.11E A graph 1150 is shown indicating the Fig.11A , Fig. 11B , Fig. 11C and Fig.11D The various bias voltages in each of the configurations of , the tilt angles in the central region of the corresponding LC active region 1102 of the device 1100. As shown in the figure, various electrode configurations (e.g., Fig. 9C , Fig.9D , Fig.9E and Fig.9F There are no significant differences in these tilt angles between the various ground electrode configurations.

[0070] Fig. 12AA device 1200 (e.g., an LC unit cell) is illustrated, and the device 1200 includes a first electrode 1202 (e.g., a via electrode), a second electrode 1204 (e.g., a ground electrode), and an LC layer 1210 disposed between the first electrode 1202 and the second electrode 1204. The device 1200 further includes a first glass substrate 1206 (e.g., a top glass substrate) and a second glass substrate 1208 (e.g., a bottom glass substrate). The first glass substrate 1206 and the second glass substrate 1208 can contain (e.g., surround) the first electrode 1202 and the second electrode 1204. In this example, and as described herein, the size of the first electrode 1202 is different from the size of the second electrode 1204. For example, the size of the second electrode 1204, which can be a ground electrode, can be smaller than the size of the first electrode 1202. Fig. 12A Also illustrated is an LC active region 1215 , which includes a portion of the LC layer 1210 positioned between the first electrode 1202 region and the second electrode 1204 region.

[0071] Fig. 12B and Fig. 12C Two types of LC configurations are illustrated for device 1200. For example, Fig. 12B A left figure and a right figure are illustrated. Each of the figures illustrates a device 1200 having an LC 1212 outside of an LC active region 1215 and an LC 1214 within the LC active region 1215. In the left figure, no voltage is applied to the LC layer 1210. Therefore, in this example, the LC 1212 and LC 1214 are initially in uniform alignment (e.g., parallel to the first glass substrate 1206 and the second glass substrate 1208). In the right figure, a voltage source 1220 is electrically connected to the first electrode 1202 and the second electrode 1204. In this example, the electrical connection from the voltage source 1220 to the second electrode 1204 is a ground connection. The voltage source 1220 can provide a bias voltage on the LC active region 1210. In this example, when the voltage source 1220 is turned on, the LC 1214 is tilted 90 degrees (e.g., perpendicular to the first glass substrate 1206 and the second glass substrate 1208). However, LC 1210 is not tilted, at least due to the smaller size of second electrode 1204 than first electrode 1202 .

[0072] Fig. 12CA left figure and a right figure are also illustrated. Each of the figures also illustrates a device 1200 having an LC 1212 outside of an LC active region 1215 and an LC 1214 within the LC active region 1215. In the left figure, no voltage is applied to the LC layer 1210. However, in this example, the LC 1212 and the LC 1214 are initially in a vertical alignment (e.g., perpendicular to the first glass substrate 1206 and the second glass substrate 1208). In the right figure, a voltage source 1220 is electrically connected to the first electrode 1202 and the second electrode 1204, wherein the electrical connection from the voltage source 1220 to the second electrode 1204 is a ground connection. The voltage source 1220 can provide a bias voltage on the LC active region 1210. In this example, when the voltage source 1220 is turned on, the LC 1214 is tilted 90 degrees (e.g., parallel to the first glass substrate 1206 and the second glass substrate 1208). However, LC 1210 is not tilted, at least due to the smaller size of second electrode 1204 than first electrode 1202 .

[0073] In some cases, when a transparent active RIS device is exposed to sunlight (e.g., for a long time), reliability issues may occur due to material degradation. For millimeter wave applications, specialized long side chain liquid crystal molecules can be used to achieve large phase differences in the millimeter wave band. These long side chains in the molecules may be affected by long-term exposure to external light (e.g., sunlight). Due to exposure, the switching characteristics of the device may be affected. For example, the switching characteristics may be reduced, resulting in changes in the color of the device (e.g., when used in LCD applications). To prevent these possible light exposures, the embodiments described herein may include one or more of a filter substrate and a light absorbing material.

[0074] For example, Fig.13A The device 1300 is illustrated, and the device 1300 includes a first glass substrate 1302, a second glass substrate 1304, and an LC layer 1306 deposited between the first glass substrate 1302 and the second glass substrate 1304. For example, each of the first glass substrate 1302 and the second glass substrate 1304 can be composed of a low-loss glass with an FSS pattern. In addition, to prevent light exposure, a filter substrate 1310 is deposited on the first glass substrate 1302. The side of the device 1300 with the filter substrate 1310 will be the side facing the potential light source (e.g., outside the liquid crystal panel). The filter substrate 1310 can include, for example, a UV / IR filter or a film composed of a UV / IR absorbing dye, a UV filter material (such as polyester or metal oxide), or any other suitable material.

[0075] In some examples, in addition to or instead of the filter substrate, the device may include a light absorbing material within the LC layer. Fig. 13BThe device 1350 is shown, and the device 1350 also includes a first glass substrate 1302, a second glass substrate 1304, and an LC layer 1306 deposited between the first glass substrate 1302 and the second glass substrate 1304. In addition, the device 1350 also includes a filter substrate 1310 deposited on the first glass substrate 1302 to prevent light exposure. The LC layer 1306 in this example includes a light absorbing and / or scattering material 1320. The light absorbing and / or scattering material 1320 can include, for example, UV / IR absorbing dyes, UV stabilizers, benzophenone, p-aminobenzoic acid (p-Aminobenzoic acid, PABA), 4-tert-butyl-4'-methoxydibenzoylmethane (avobenzone, avobenzone) or methoxycinnamate (emethoxycinnamate, EHMC). The UV scattering material can include, for example, titanium oxide (TiO2) or zinc oxide (ZnO).

[0076] Exemplary Embodiments

[0077] In some embodiments, the unit cell device includes a first metal layer and a second metal layer, wherein each of the first metal layer and the second metal layer is deposited within a glass substrate. The first metal layer has a first size, and the second metal layer has a second size, wherein the first size is different from the second size. In addition, the unit cell device includes an LC layer disposed between the first metal layer and the second metal layer.

[0078] In some embodiments, the second dimension is smaller than the first dimension. In some embodiments, the second dimension is at least 10% smaller than the first dimension.

[0079] In some embodiments, the first metal layer comprises a plurality of columns and the second metal layer comprises a plurality of rows. In some embodiments, each of the plurality of columns is electrically connected to a voltage source. In some embodiments, each of the plurality of rows is connected to ground. In some embodiments, each of the plurality of rows is connected to a voltage source. In some embodiments, each of the plurality of columns comprises a first plurality of LC active layers, and wherein each of the plurality of rows comprises a second plurality of LC active layers. In some embodiments, each of the first plurality of LC active layers is laterally offset from one of the second plurality of LC active layers.

[0080] In some embodiments, the first metal layer is connected to at least one voltage source and the second metal layer is connected to ground.

[0081] In some embodiments, the glass substrate includes a first glass substrate portion and a second glass substrate portion, wherein a first metal layer is deposited between the first glass substrate portion and a liquid crystal layer, and wherein a second metal layer is deposited between the liquid crystal layer and the second glass substrate portion, the device includes a third metal layer, wherein the second glass substrate portion is deposited between the second metal layer and the third metal layer.

[0082] In some embodiments, a device comprises a filter substrate deposited on a glass substrate.

[0083] In some embodiments, the liquid crystal layer includes a light absorbing material.

[0084] In some embodiments, the device includes a plurality of LC active regions between a first metal plate and a second metal plate, wherein when a bias is applied between the first metal plate and the second metal plate, liquid crystals of the liquid crystal layer within the plurality of LC active regions tilt. In some embodiments, when a bias is applied between the first metal plate and the second metal plate, liquid crystals of the liquid crystal layer outside the plurality of LC active regions do not tilt.

[0085] In some embodiments, a unit cell device comprises a first metal layer and a second metal layer deposited within a glass substrate, wherein the first metal layer and the second metal layer are laterally offset. The first metal layer comprises a plurality of columns, wherein each of the plurality of columns comprises a first plurality of LC active layers. The second metal layer comprises a plurality of rows, wherein each of the plurality of rows comprises a second plurality of LC active layers. The unit cell further comprises an LC layer deposited between the first metal layer and the second metal layer.

[0086] In some examples, a method, such as by an apparatus including one or more processors that execute instructions (e.g., a pick-and-place machine), includes depositing a metal material on a first glass substrate to form a first metal layer having a first size. The method may also include depositing an LC material on the first metal layer to form an LC layer. In addition, the method may also include depositing a metal material on the LC layer to form a second metal layer having a second size, the second size being different from the first size. The method may also include depositing a second glass substrate on the second metal layer.

[0087] In some examples, a method, such as by a device including one or more processors that execute instructions (e.g., a pick-and-place machine), includes depositing a metal material on a first glass substrate to form a first metal layer having a first plurality of LC active layers. The method may also include depositing an LC material on the first metal layer to form an LC layer. In addition, the method may also include depositing a metal material on the LC layer to form a second metal layer having a second plurality of LC active layers. The method may also include depositing a second glass substrate on the second metal layer.

[0088] In some embodiments, a non-transitory computer-readable medium stores instructions that, when executed by one or more processors, cause an apparatus such as a pick-and-place machine to perform a method comprising the steps of depositing a metal material on a first glass substrate to form a first metal layer having a first size. The method may also include depositing an LC material on the first metal layer to form an LC layer. In addition, the method may also include depositing a metal material on the LC layer to form a second metal layer having a second size, the second size being different from the first size. The method may also include depositing a second glass substrate on the second metal layer.

[0089] In some embodiments, a non-transitory computer-readable medium stores instructions that, when executed by one or more processors, cause an apparatus such as a pick-and-place machine to perform a method comprising the steps of depositing a metal material on a first glass substrate to form a first metal layer having a first plurality of LC active layers. The method may also include depositing an LC material on the first metal layer to form an LC layer. In addition, the method may also include depositing a metal material on the LC layer to form a second metal layer having a second plurality of LC active layers. The method may also include depositing a second glass substrate on the second metal layer.

[0090] Although the above describes a method, it should be understood that many other ways may be used to perform the actions associated with the above method. For example, the order of some operations may be changed, and some operations described may be optional.

[0091] In addition, the methods and systems described herein may be embodied at least in part in the form of computer-implemented processes and devices for practicing these processes. The disclosed methods may also be embodied at least in part in the form of tangible non-temporary machine-readable storage media programmed by computer program code. For example, the steps of the method may be embodied in hardware, in executable instructions executed by a processor (e.g., software), or in a combination of the two. The medium may include, for example, RAM, ROM, CD-ROM, DVD-ROM, BD-ROM, hard disk, flash memory, or any other non-temporary machine-readable storage medium. When the computer program code is loaded into a computer and executed by the computer, the computer becomes a device for practicing the method. The method may also be embodied at least in part in the form of a computer, wherein the computer program code is loaded into or executed in the computer so that the computer becomes a special-purpose computer for practicing the method. When implemented on a general-purpose processor, the computer program code segment configures the processor to create a specific logic circuit. Alternatively, the method may be embodied at least in part in a special application integrated circuit for executing the method.

[0092] The foregoing is provided for the purpose of illustrating, explaining and describing the embodiments of the present disclosure. Modifications and adaptations to these embodiments will be apparent to those skilled in the art to which the present invention belongs and can be made without departing from the scope or spirit of the present disclosure.

Claims

1. A device, comprising: Glass substrate; a first metal layer and a second metal layer, wherein each of the first metal layer and the second metal layer is deposited within the glass substrate, wherein the first metal layer has a first size and the second metal layer has a second size, wherein the first size is different from the second size; and A liquid crystal layer is deposited between the first metal layer and the second metal layer.

2. The device of claim 1, wherein: a first metal layer comprising a plurality of columns; and The second metal layer includes a plurality of rows, wherein the plurality of columns are orthogonal to the plurality of rows.

3. The device of claim 2, wherein each of the plurality of columns is electrically connected to a first voltage source. The device of claim 3 , wherein each of the plurality of rows is connected to ground.

5. The device of claim 3, wherein each of the plurality of rows is connected to a second voltage source.

6. The apparatus of claim 2, wherein each of the plurality of columns comprises a first plurality of LC active layers, and wherein each of the plurality of rows comprises a second plurality of LC active layers.

7. The device of claim 6, wherein each of the first plurality of LC active layers is laterally offset from one of the second plurality of LC active layers.

8. The device of claim 1, wherein the second size is smaller than the first size.

9. The device of claim 5, wherein the second dimension is at least 10% smaller than the first dimension.

10. The apparatus of claim 1, wherein the first metal layer is connected to a voltage source and the second metal layer is connected to ground.

11. The device of claim 1 , wherein the glass substrate comprises a first glass substrate portion and a second glass substrate portion, wherein the first metal layer is deposited between the first glass substrate portion and the liquid crystal layer, and wherein the second metal layer is deposited between the liquid crystal layer and the second glass substrate portion, the device comprising a third metal layer, wherein the second glass substrate portion is deposited between the second metal layer and the third metal layer.

12. The device of claim 1, comprising a filter substrate deposited on the glass substrate.

13. The device of claim 1, wherein the liquid crystal layer comprises a light absorbing material.

14. The device of claim 1, comprising a plurality of LC active regions between the first metal plate and the second metal plate, wherein when a bias voltage is applied between the first metal plate and the second metal plate, liquid crystals of the liquid crystal layer within the plurality of LC active regions tilt. 15 . The device of claim 14 , wherein when the bias voltage is applied between the first metal plate and the second metal plate, liquid crystals of the liquid crystal layer outside the plurality of LC active regions are not tilted.

16. A device, comprising: Glass substrate; a first metal layer and a second metal layer, wherein each of the first metal layer and the second metal layer is deposited within the glass substrate, wherein the first metal layer includes a plurality of columns and the second metal layer includes a plurality of rows, and wherein each of the plurality of columns and each of the plurality of rows are electrically connected to a first voltage source and a second voltage source, respectively; and A liquid crystal layer is deposited between the first metal layer and the second metal layer.

17. The device of claim 16, wherein each of the plurality of columns comprises a first plurality of LC active layers, and wherein each of the plurality of rows comprises a second plurality of LC active layers, and wherein each of the first plurality of LC active layers is laterally offset from one of the second plurality of LC active layers.

18. A method comprising: Depositing a metal material on the first glass substrate to form a first metal layer having a first size; depositing a liquid crystal (LC) material on the first metal layer to form a liquid crystal layer; depositing the metal material on the liquid crystal layer to form a second metal layer having a second size different from the first size; as well as A second glass substrate is deposited on the second metal layer.

19. The method of claim 18, wherein: The first metal layer comprises a plurality of columns; and The second metal layer includes a plurality of rows.

20. The method of claim 19, wherein each of the plurality of columns comprises a first plurality of LC active layers, and wherein each of the plurality of rows comprises a second plurality of LC active layers.

Images