An electrically controlled terahertz broadband large phase-shifting phase shifter based on graphene-metal metasurface

Abstract

This invention relates to an electrically controlled terahertz broadband large phase shifter based on a graphene-metal metasurface, comprising a high-resistivity silicon substrate and a two-dimensional array thereon. Each array unit includes three vertically aligned rectangular metal frames, three embedded graphene rectangular frames, three sets of rectangular metal blocks, and two rectangular metal blocks. Each set of four rectangular metal blocks is arranged in pairs on the top and bottom sides of the graphene rectangular frames. The two rectangular metal blocks are connected to the middle of the left and right sides of the array unit, respectively. Two lead-out electrodes are located on both sides of the two-dimensional array and are connected to the positive and negative terminals of a DC power supply, respectively. As the bias voltage increases, the absorption peak of the terahertz wave generated by the phase shifter gradually shifts to lower frequencies, resulting in a broadband, large phase shift to the right of the absorption peak. This electrically controlled terahertz broadband large phase shifter has low manufacturing cost and fast response speed, and has potential application value in terahertz phased array radar, broadband wireless communication, and other fields.

Description

Technical Field

[0001] This invention relates to the field of terahertz technology, and in particular to an electrically controlled terahertz broadband large-phase-shifting phase shifter based on a graphene-metal metasurface. Background Technology

[0002] In recent years, terahertz waves have attracted considerable attention due to their superior characteristics, such as strong penetration, high security, and ultra-wide bandwidth, and hold significant application value in future new-type radar and 6G broadband wireless communication. These applications all rely on the control of the terahertz wave phase, and the commonly used phase control device is the terahertz phase shifter. Currently, phase control of terahertz waves is mainly achieved by designing metasurface structures. However, existing terahertz phase shifters struggle to achieve wide-band, large-phase-shift control, which greatly limits their application areas. Summary of the Invention

[0003] The purpose of this invention is to disclose an electrically controlled terahertz broadband large phase shifter based on a graphene-metal metasurface. The device includes a high-resistivity silicon substrate and a two-dimensional array on the substrate. Each array unit comprises three vertically aligned rectangular metal frames, three graphene rectangular frames embedded within the rectangular metal frames, three sets of rectangular metal blocks located within the graphene rectangular frames, and two rectangular metal blocks located on the left and right sides of the array unit. Each set of rectangular metal blocks includes four metal blocks of equal size, two of which are connected to the top edge of the graphene rectangular frame, and the other two are connected to the bottom edge of the graphene frame. The two rectangular metal blocks are located on the left and right sides of the unit and connected to the middle of the left and right sides of the central rectangular metal frame. Two lead-out electrodes are located on both sides of the two-dimensional array and are connected to the positive and negative terminals of a DC power supply, respectively. When a vertically polarized terahertz wave is incident, an absorption peak is generated through the phase shifter. As the bias voltage increases, the absorption peak gradually shifts to lower frequencies, and a broadband, large phase shift occurs to the right of the absorption peak.

[0004] This invention discloses an electrically controlled terahertz broadband large-phase shifter based on a graphene-metal metasurface, comprising a high-resistivity silicon substrate and a two-dimensional array composed of metal-graphene on the high-resistivity silicon substrate. The side length of the two-dimensional array is 1.0 to 1.5 times the diameter of the incident terahertz beam. The length and width of the high-resistivity silicon substrate are both larger than the length and width of the two-dimensional array. The terahertz wave is incident from above the two-dimensional array, passes through the two-dimensional array, and exits after passing through the high-resistivity silicon substrate.

[0005] Each array unit of the two-dimensional array includes three rectangular metal frames arranged side by side along the vertical direction, three graphene rectangular frames embedded in the rectangular metal frames, three sets of rectangular metal blocks located in the graphene rectangular frames, and two rectangular metal blocks located on the left and right sides of the array unit respectively.

[0006] Each of the metal structures is a strip of metal made of any one of gold, aluminum, or copper.

[0007] The three rectangular metal frames are arranged vertically, and the top and bottom sides of adjacent rectangular metal frames are connected.

[0008] The three graphene rectangular frames are respectively embedded in three rectangular metal frames.

[0009] Each of the three groups of rectangular metal blocks includes four metal blocks of equal size, two of which are connected to the top edge of the graphene rectangular frame, and the other two are connected to the bottom edge of the graphene frame.

[0010] The two rectangular metal blocks are located on both sides of the unit and are connected to the middle of the left and right sides of the middle rectangular metal frame.

[0011] Two lead-out electrodes are located on both sides of the two-dimensional array, connected to the positive and negative electrodes of the DC power supply, respectively, and connected by a switch. The electrodes on both sides are connected to the leftmost rectangular metal block in the first column on the left and the rightmost rectangular metal block in the last column on the right of the two-dimensional array, respectively.

[0012] When the switch connecting the electrodes to the DC power supply is turned on, all three graphene patches have low conductivity, meaning the rectangular metal frame of the array unit is blocked from connecting the rectangular metal blocks at the top and bottom edges of the graphene rectangular frame. When the switch connecting the electrodes to the DC power supply is closed, the Fermi level of the graphene changes, and the conductivity of the graphene frame increases, meaning the rectangular metal frame is connected to the rectangular metal blocks at the top and bottom edges of the graphene rectangular frame. At this time, the phase shifter operates in phase modulation mode.

[0013] The voltage of the DC power supply is 12V to 24V.

[0014] In the two-dimensional array, the longitudinal and transverse widths of an array cell are the same, ranging from 100 micrometers to 104 micrometers.

[0015] The rectangular metal frame and rectangular metal block are metal strips made of any one of gold, aluminum or copper, with a thickness of 0.2 micrometers to 0.8 micrometers.

[0016] The rectangular metal frame has a longitudinal length of 29 to 31 micrometers, a transverse length of 90 to 94 micrometers, and a width of 3 to 5 micrometers for each of its four sides.

[0017] The graphene rectangular frame is a single layer of graphene material with a thickness of 1 nanometer. Its longitudinal length is 23-25 ​​micrometers, its transverse length is 80-88 micrometers, and the width of the four sides forming the rectangular frame is 3-5 micrometers.

[0018] The rectangular metal block located within the graphene rectangular frame has a longitudinal length of 5.5 micrometers to 7.5 micrometers and a lateral length of 4 micrometers to 18 micrometers.

[0019] The rectangular metal blocks located on the left and right sides of the array unit have a longitudinal length of 6 to 10 micrometers and a lateral length of 3 to 5 micrometers.

[0020] Compared with the prior art, the advantages of the electrically controlled terahertz broadband large phase shift phase shifter based on graphene-metal metasurface of the present invention are: 1. By controlling the closing of the DC power supply switch, a broadband and large phase shift modulation effect can be achieved, which is suitable for different occasions; 2. Its structure is not much different from the existing general terahertz modulation devices, only adding electrodes and DC power supply, which is easy to implement and convenient to operate. Attached Figure Description

[0021] Figure 1 A schematic diagram of the three-dimensional structure of an electrically controlled terahertz broadband large phase-shifting phase shifter based on a graphene-metal metasurface;

[0022] Figure 2 for Figure 1 Schematic diagram of the AA section;

[0023] Figure 3 This is a schematic diagram of an array cell structure;

[0024] Figure 4 for Figure 1 Top view of a two-dimensional array;

[0025] Figure 5 This invention presents the transmittance and phase change spectra of terahertz waves transmitted through a phase shifter before and after the DC power switch is closed, when vertically polarized terahertz waves are incident.

[0026] The diagram is labeled as follows: 1. High-resistivity silicon substrate; 2. Two-dimensional array; 21. Rectangular metal frame; 22. Graphene rectangular frame; 23. Rectangular metal block located within the graphene rectangular frame; 24. Rectangular metal blocks located on the left and right sides of the array unit; 25. Lead-out metal electrode structure. Detailed Implementation

[0027] The following describes in detail, with reference to the accompanying drawings and specific embodiments, a scheme for an electrically controlled terahertz broadband large phase-shifting phase shifter based on a graphene-metal metasurface according to the present invention.

[0028] A schematic diagram of an embodiment of an electrically controlled terahertz broadband large-phase shifter based on a graphene-metal metasurface is shown below. Figure 1 and Figure 2 As shown, it includes a high-resistivity silicon substrate 1 and a two-dimensional array 2 located on the high-resistivity silicon substrate 1. In this example, the diameter of the incident terahertz beam is 500 micrometers.

[0029] In this example, the length and width of the high-resistivity silicon substrate 1 are both greater than those of the two-dimensional array 2. The thickness of the high-resistivity silicon substrate 1 in this example is 500 micrometers. Terahertz waves incident from above the two-dimensional array 2 pass through the two-dimensional array 2 and the high-resistivity silicon substrate 1 before exiting.

[0030] like Figure 3 and 4 As shown, each array unit of the two-dimensional array 2 in this example includes three rectangular metal frames 21 arranged side by side along the vertical direction, three graphene rectangular frames 22 embedded in the rectangular metal frames, three sets of rectangular metal blocks 23 located inside the graphene rectangular frames, and two rectangular metal blocks 24 located on the left and right sides of the array unit. The length and width of one array unit are L = 100 micrometers.

[0031] In this example, the rectangular metal frames 21 are arranged vertically, with adjacent rectangular metal frames 21 connected and sharing a side. The longitudinal length of each rectangular metal frame 21 is a = 33 micrometers, the transverse length is b = 92 micrometers, and the width of the four sides of the rectangular metal frame 21 is w1 = 4 micrometers.

[0032] In this example, the graphene rectangular frame 22 is embedded with three rectangular metal frames 21. Each graphene rectangular frame 22 has a longitudinal length of 25 micrometers, a transverse length of 84 micrometers, a width w2 of 4 micrometers on each of its four sides, and a thickness of 1 nm.

[0033] In this example, a group of identical rectangular metal blocks 23 are located at the center of the inner side of the graphene rectangular frame 22. Two of them are connected to the top edge of the graphene rectangular frame 22, and the other two are connected to the bottom edge of the graphene rectangular frame 22. The longitudinal length w3 = 6.5 micrometers and the lateral length w4 = 8 micrometers of each metal block located within the graphene rectangular frame 22 are respectively. The lateral gap i = 8 micrometers between two rectangular metal blocks located on the same side, and the longitudinal gap g = 4 micrometers between the rectangular metal blocks located on the top and bottom edges respectively.

[0034] In this example, two rectangular metal blocks 24 are located on the left and right sides of the array unit and are connected to the middle of the left and right sides of the central rectangular metal frame 21. Each metal block 24 has a vertical length of 8 micrometers and a horizontal length of 4 micrometers.

[0035] In this example, the two-dimensional array 2 has an electrode 25 on each of its left and right sides, which are respectively connected to the positive and negative terminals of a DC power supply, and there is a switch on the connection line. The electrodes 25 on both sides are connected to the leftmost rectangular metal block 24 in the first column on the left side and the rightmost rectangular metal block 24 in the last column on the right side of the two-dimensional array 2, respectively.

[0036] When the switch connecting electrode 25 to the DC power supply is turned on, all three graphene patches 22 have low conductivity, meaning the rectangular metal frame 21 of the array unit is blocked from connecting the upper and lower edges of the graphene rectangular frame 22 to the rectangular metal block 23. When the switch connecting electrode 25 to the DC power supply is closed, the Fermi level of the graphene changes, and the conductivity of the graphene frame 22 increases, meaning the rectangular metal frame 21 is connected to the upper and lower edges of the graphene rectangular frame 22 to the rectangular metal block 23. At this time, the phase shifter operates in phase modulation mode. The transmittance diagram of the terahertz wave incident on and passing through this phase shifter, as well as the phase versus frequency curve, are shown as the solid line curve in the figure.

[0037] The above embodiments are merely specific examples to further illustrate the purpose, technical solution, and beneficial effects of the present invention, and the present invention is not limited thereto. Any modifications, equivalent substitutions, improvements, etc., made within the scope of the disclosure of the present invention are included within the protection scope of the present invention.

Claims

1. An electrically controlled terahertz broadband large-phase shifter based on a graphene-metal metasurface, comprising a high-resistivity silicon substrate (1) and a two-dimensional array (2) located on the upper surface of the high-resistivity silicon substrate (1); the side length of the two-dimensional array (2) is 1.0 to 1.5 times the diameter of the incident terahertz beam; the length and width of the high-resistivity silicon substrate (1) are both greater than the length and width of the two-dimensional array (2); the terahertz wave is incident from above the two-dimensional array (2), modulated by passing through the two-dimensional array (2), and emitted after passing through the high-resistivity silicon substrate (1); characterized in that: Each array unit of the two-dimensional array (2) includes three rectangular metal frames (21) arranged side by side along the vertical direction, three graphene rectangular frames (22) embedded in the rectangular metal frames, three sets of rectangular metal blocks (23) located in the graphene rectangular frames (22), and two rectangular metal blocks (24) located on the left and right sides of the array unit respectively. The three rectangular metal frames (21) are arranged vertically, and the upper and lower sides of adjacent rectangular metal frames (21) are connected. The three graphene rectangular frames (22) are respectively embedded in three rectangular metal frames; Each of the three groups of rectangular metal blocks (23) includes four metal blocks of equal size, two of which are connected to the top of the graphene rectangular frame (22), and the other two are connected to the bottom of the graphene rectangular frame (22). The two rectangular metal blocks (24) are located on both sides of the array unit and are connected to the middle of the left and right sides of the middle rectangular metal frame (21); Two lead-out electrodes (25) are located on both sides of the two-dimensional array and are connected to the positive and negative electrodes of the DC power supply respectively. There is a switch on the connection line. The electrodes (25) on both sides are connected to the leftmost rectangular metal block (24) of the first column on the left side of the two-dimensional array (2) and the rightmost rectangular metal block (24) of the last column on the right side respectively. When the switch connecting the electrode (25) to the DC power supply is turned on, all three graphene rectangular frames (22) have low conductivity, meaning that the rectangular metal frame (21) of the array unit and the rectangular metal block (23) connected to the top and bottom edges of the graphene rectangular frame (22) are blocked; when the switch connecting the electrode to the DC power supply is closed, the Fermi level of the graphene changes, and the conductivity of the graphene rectangular frame (22) increases, meaning that the rectangular metal frame (21) and the rectangular metal block (23) connected to the top and bottom edges of the graphene rectangular frame (22) are connected, and at this time the phase shifter works in the phase modulation state.

2. The electrically controlled terahertz broadband large-phase shifter based on graphene-metal metasurface according to claim 1, characterized in that: The voltage of the DC power supply is 12V to 24V.

3. The electrically controlled terahertz broadband large-phase shifter based on graphene-metal metasurface according to claim 1, characterized in that: The longitudinal and transverse lengths of one array unit in the two-dimensional array (2) are both 100 micrometers to 104 micrometers.

4. The electrically controlled terahertz broadband large-phase shifter based on graphene-metal metasurface according to claim 1, characterized in that: The rectangular metal frame (21) and the rectangular metal block are metal strips made of any one of gold, aluminum or copper, with a thickness of 0.2 micrometers to 0.8 micrometers.

5. The electrically controlled terahertz broadband large-phase shifter based on graphene-metal metasurface according to claim 1, characterized in that: The graphene rectangular frame (22) is a single layer of graphene with a thickness of 1 nanometer.

6. The electrically controlled terahertz broadband large-phase shifter based on graphene-metal metasurface according to claim 4, characterized in that: The rectangular metal frame (21) has a longitudinal length of 29 micrometers to 31 micrometers, a transverse length of 90 micrometers to 94 micrometers, and the width of the four sides of the rectangular metal frame (21) is 3 micrometers to 5 micrometers.

7. The electrically controlled terahertz broadband large-phase shifter based on graphene-metal metasurface according to claim 5, characterized in that: The graphene rectangular frame (22) is a single layer of graphene material with a thickness of 1 nanometer, a longitudinal length of 23 micrometers to 25 micrometers, a transverse length of 80 micrometers to 88 micrometers, and the width of the four sides of the rectangular frame is 3 micrometers to 5 micrometers.

8. The electrically controlled terahertz broadband large-phase shifter based on graphene-metal metasurface according to claim 4, characterized in that: The rectangular metal block (23) located within the graphene rectangular frame (22) has a longitudinal length of 5.5 micrometers to 7.5 micrometers and a transverse length of 4 micrometers to 18 micrometers. The transverse gap between two rectangular metal blocks (23) located on the same side is 4 micrometers to 16 micrometers, and the longitudinal gap between rectangular metal blocks (23) located on the upper and lower sides is 4 micrometers to 5 micrometers.

9. The electrically controlled terahertz broadband large-phase shifter based on graphene-metal metasurface according to claim 4, characterized in that: The rectangular metal blocks (24) located on the left and right sides of the array unit have a longitudinal length of 6 micrometers to 10 micrometers and a transverse length of 3 micrometers to 5 micrometers.

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