A reconfigurable electromagnetic metasurface device and method

Abstract

A reconfigurable electromagnetic metasurface device and method, including: an ultrathin porous panel, a solution pool, a micro-nano motor cluster, an ultrasonic crystal oscillator and a rotating magnetic field generating device. The ultrathin porous panel is placed above the solution pool, and can be aligned with the solution pool with the help of positioning rods at the four corners of the solution pool, and fixed to the upper surface of the solution pool through the protruding strips on the upper part of the solution pool. The micro-nano motor cluster is distributed in the solution pool. The ultrasonic crystal oscillator is placed around the solution pool, and can generate a graphical ultrasonic signal in the solution pool. The rotating magnetic field generating device is placed at the bottom of the solution pool, and can generate a uniform magnetic field in the space around the solution pool. The reconfigurable electromagnetic metasurface device provided by the present invention can control the micro-nano motor cluster to enter the porous panel channel by adjusting the phase, frequency, intensity, direction and other parameters of the ultrasonic and magnetic fields, so as to construct a reconfigurable electromagnetic metasurface, which has important application value in the fields of millimeter wave communication and topological photonics.

Description

Technical Field

[0001] The present invention belongs to the field of electromagnetic metasurfaces, and in particular relates to a reconfigurable electromagnetic metasurface device and method. Background Art

[0002] Electromagnetic metasurface, also known as electromagnetic metastructure surface, is an artificial electromagnetic material composed of subwavelength structural units arranged periodically or non-periodically on a certain plane. By precisely designing the geometry, size, direction, array combination, and material properties (such as dielectric constant) of the subwavelength structural units, the electromagnetic waves incident on the metasurface can be precisely controlled to achieve functions such as phase reshaping, beam selection, and directional emission. This makes electromagnetic metasurfaces have important application value in many fields such as millimeter wave communications, topological photonics, electromagnetic superlenses, and electromagnetic stealth. Traditional electromagnetic metasurfaces are mostly constructed on substrates through micro-nano processing technology. This static metasurface often has a solidified structure and a single function, which greatly limits the time domain control capability of the metasurface and poses a great challenge to the multifunctionalization of the metasurface. How to achieve dynamic adjustability of the metasurface structure is a major technical challenge.

[0003] In order to achieve dynamic regulation of electromagnetic metasurfaces, researchers have designed a variety of different strategies and technical solutions. The most direct method is to grow microstructure units on a flexible material (such as PDMS) as a substrate, and adjust the size of the flexible substrate through stress to change the shape and spacing of the surface microstructure units, thereby achieving dynamic regulation of the metasurface. In addition, some researchers use phase change materials (such as VO2) to construct metasurface structural units, and induce phase change through external stimuli (such as heat, light, current, etc.) to convert the electromagnetic properties of the unit, thereby achieving dynamic regulation of the electromagnetic properties of the metasurface. In addition, Chinese scholars have also introduced field programmable logic gates (FPGAs) into metasurface design to achieve field programmable electromagnetic metasurfaces. These design solutions have their own advantages, but they also have certain limitations. For example, the stress-regulated metasurface does not have enough precision in regulating electromagnetic waves; phase change induced regulation is often an overall regulation of all structural units of the metasurface, and it is difficult to achieve regulation of a single unit; the frequency band of field programmable metasurface regulation is generally in the millimeter wave band, and the application band is difficult to further expand.

[0004] In summary, the invention of an electromagnetic metasurface device with dynamic control capability has important application value in many fields. In particular, the reconfigurable metasurface structural unit will have important innovative significance. No similar technology has been found so far. Summary of the invention

[0005] In view of the problem that the existing electromagnetic metasurface has weak reconfigurability, the purpose of the present invention is to provide a reconfigurable electromagnetic metasurface device and method. The metasurface array of the present invention is composed of magnetic micro-nano motors graphically arranged on the surface of a porous plate. The cluster of micro-nano motors is controlled by the combined action of an ultrasonic field and a rotating magnetic field to achieve multifunctional reconstruction of the electromagnetic metasurface.

[0006] In order to solve the above problems, the technical solution of the present invention is:

[0007] A reconfigurable electromagnetic metasurface device comprises a solution pool filled with a solution, a motor cluster is arranged in the solution, a protruding bar is arranged on the upper part of the solution pool, a panel is placed on the protruding bar, a plurality of microholes are arranged on the panel, a rotating magnetic field generating device is arranged below the solution pool, and a plurality of ultrasonic crystal oscillators are arranged around the solution pool.

[0008] The microholes are circular or elliptical, and are arranged in an array on the panel.

[0009] The micropores are trumpet-shaped, thin at the top and thick at the bottom.

[0010] Positioning rods are provided at the four corners of the solution pool.

[0011] The solution is a sodium hexadecyl sulfate solution, and the liquid level is consistent with the height of the protruding strips.

[0012] The motor cluster includes multiple micro-nano motors, each of which includes a head, a middle part and a tail. The diameters of the head and the tail are both smaller than the diameter of the microhole. The head and the tail are both asymmetric truncated cones. The head is covered with ferromagnetic material, and the micro-nano motor is embedded with a ferromagnetic spiral.

[0013] The ferromagnetic material is nickel-iron material.

[0014] The head, middle and tail are made of silica.

[0015] The magnetic field rotating magnetic field generating device is an electromagnet or a rotating permanent magnet.

[0016] A method for a reconfigurable electromagnetic metasurface device comprises the following steps:

[0017] The first step is to apply equal-amplitude and in-phase signals to the ultrasonic crystal oscillator to drive the micro-nano motors to be centrally symmetrically distributed in the solution pool. At the same time, the frequency of the ultrasonic crystal oscillator is adjusted to 1-4 MHz so that the motor cluster density period is smaller than the wavelength of the sound wave.

[0018] The second step is to start the rotating magnetic field while maintaining the ultrasonic field drive. The micro-nano motor will stand upright along the magnetic field line, flip the magnetic field polarity, and change the direction of the motor when standing upright.

[0019] The third step is to rotate the magnetic field to make the motor move up and down, thereby entering or exiting the micropores of the ultra-thin porous panel, thereby forming a graphical distribution of the electric polarization rate on the surface of the ultra-thin porous panel, thereby constructing an electromagnetic supersurface;

[0020] The fourth step is to select the wavelength or direction of the reflected wave of the incident electromagnetic wave toward the electromagnetic metasurface, and to adjust the phase and intensity of the ultrasonic signal of the ultrasonic crystal oscillator to adjust the density distribution pattern of the micro-nano motor cluster, thereby realizing a reconfigurable electromagnetic metasurface.

[0021] The beneficial effects of the present invention are:

[0022] (1) This device can induce the micro-nano motor cluster to present a graphical distribution in the solution pool through the ultrasonic field, and can use the rotating magnetic field to control the graphically distributed micro-nano motor cluster to enter the pores of the porous thin plate, thereby adjusting the electromagnetic properties of each unit of the porous thin plate and realizing the electromagnetic metasurface function.

[0023] (2) By controlling the motor head or tail to enter the channel through a rotating magnetic field, the overall control of the metasurface dielectric constant and magnetic permeability can be achieved.

[0024] (3) By adjusting the phase and intensity of the ultrasonic field, the graphical pattern of the micro-nanomotor array can be changed, thereby achieving electromagnetic metasurface reconstruction. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described below in conjunction with the accompanying drawings:

[0026] Figure 1 It is a structural schematic diagram of the present invention,

[0027] Figure 2 is a schematic diagram of the structure of the panel of the present invention,

[0028] Figure 3 is a schematic diagram of the cross-sectional structure of the micropores of the present invention,

[0029] Figure 4 is a schematic diagram of the structure of the micro-nano motor of the present invention,

[0030] Figure 5 This is a schematic diagram of the structure of the micro-nano motor entering the micro-hole according to the present invention.

[0031] Figure 6 It is a schematic diagram of the structure of two electromagnetic supersurfaces according to the present invention.

[0032] In the figure: panel 1, solution pool 2, micro-nano motor 3, protruding strip 5, ultrasonic crystal oscillator 6, rotating magnetic field generating device 7, magnetic flux lines of rotating magnetic field 8, rotation direction of spiral magnetic field 9, magnetic field lines 10, micropores 11, micropores not filled with micro-nano motors 12, micropores filled with micro-nano motors 13, head 31, middle part 32, tail 33, ferromagnetic spiral 34. DETAILED DESCRIPTION

[0033] like Figures 1 to 6 As shown, a reconfigurable electromagnetic metasurface device includes a solution pool 2, the solution pool 2 is filled with a solution, a motor cluster is arranged in the solution, a protrusion bar 5 is arranged on the upper part of the solution pool 2, a panel 1 is placed on the protrusion bar 5, a plurality of microholes 11 are arranged on the panel 1, a rotating magnetic field generating device 7 is arranged below the solution pool 2, the rotating magnetic field generating device 7 is used to generate a uniform magnetic field in the space around the solution pool 2, 6 groups of 12 ultrasonic crystal oscillators 6 are symmetrically buried around the solution pool 2, the ultrasonic crystal oscillators 6 are used to generate graphical ultrasonic signals in the solution pool 2, and the ultrasonic crystal oscillator 6 signals are controlled by an external computer.

[0034] The micropores 11 are circular or elliptical, and are arranged in an array on the panel 1. The panel 1 is made of silicon dioxide.

[0035] The micropore 11 is in the shape of a trumpet with a thin top and a thick bottom. The diameter of the micropore 11 is 600 nanometers at the top and 1 micrometer at the bottom.

[0036] Positioning rods 4 are provided at the four corners of the solution pool 2. The positioning rods 4 correspond to the four corners of the panel 1 and are used to assist in alignment with the solution pool 2. The solution pool 2 is a square with a side length of 2 cm, and the positioning rods 4 are 5 mm high.

[0037] The solution is a sodium hexadecyl sulfate solution, and the liquid level is consistent with the height of the protruding strip 5.

[0038] The motor cluster includes 103 micro-nano motors 3, and the micro-nano motor 3 includes a head 31, a middle part 32 and a tail 33. The diameters of the top of the head 31 and the top of the tail 33 are both 500 nanometers, the diameter of the middle part 32 close to the head 31 is 700 nanometers, and the diameter of the middle part 32 close to the tail 33 is 800 nanometers. The head 31 and the tail 33 are both asymmetric truncated cones, and the head 31 is covered with ferromagnetic material. A ferromagnetic helix 34 is embedded in the micro-nano motor 3. The ferromagnetic helix 34 is made of cobalt-iron alloy, and the helical chirality is left-handed.

[0039] The ferromagnetic material is nickel-iron material.

[0040] The head portion 31, the middle portion 32 and the tail portion 33 are made of silicon dioxide.

[0041] The magnetic field rotating magnetic field generating device 7 is an electromagnet or a rotating permanent magnet. The permanent magnet is a cylindrical permanent magnet with a radius of 10 cm, which is much larger than the solution pool 2 and is the rotating magnetic field generating device 7.

[0042] A method for a reconfigurable electromagnetic metasurface device comprises the following steps:

[0043] The first step is to apply equal-amplitude and in-phase signals to the ultrasonic crystal oscillator 6 to drive the micro-nano motor 3 with an asymmetric structure to be centrally symmetrically distributed in the solution pool 2; by adjusting the frequency of the ultrasonic crystal oscillator 6 to 1-4 MHz, the motor cluster density period is made smaller than the wavelength of the sound wave, and the wavelength reaches the order of 1 micron to 100 microns.

[0044] The second step is to start the rotating magnetic field while maintaining the ultrasonic field drive. Then the micro-nano motor 3 will stand upright along the magnetic field line 10. Figure 5 By reversing the magnetic field polarity, such as from N-pole up to S-pole up, you can change the orientation of the motor when it is upright.

[0045] The third step is to rotate the magnetic field to make the motor move up and down, thereby entering or exiting the micropores 11 of the ultra-thin porous panel 1. This forms a graphical distribution of the electric susceptibility on the surface of the ultra-thin porous panel 1, thereby constructing an electromagnetic super surface.

[0046] Step 4: Figure 6 As shown, the electromagnetic metasurface selects the wavelength or direction of the incident electromagnetic wave reflection wave. By adjusting the phase and intensity of the ultrasonic signal of the ultrasonic crystal oscillator, the density distribution pattern of the micro-nano motor 3 cluster is adjusted, thereby realizing a reconfigurable electromagnetic metasurface.

Claims

1. A reconfigurable electromagnetic metasurface device, characterized in that: The invention comprises a solution pool (2), wherein the solution pool (2) is filled with a solution, a motor cluster is arranged in the solution, a protruding strip (5) is arranged on the upper part of the solution pool (2), a panel (1) is placed on the protruding strip (5), a plurality of microholes (11) are arranged on the panel (1), a rotating magnetic field generating device (7) is arranged below the solution pool (2), the rotating magnetic field generating device (7) is used to generate a uniform magnetic field in the space around the solution pool (2), 6 groups of 12 ultrasonic crystal oscillators (6) are symmetrically buried around the solution pool (2), and the ultrasonic crystal oscillators (6) are used to generate a graphical ultrasonic signal in the solution pool (2); the microholes (11) are circular or elliptical, and each microhole (11) is arranged in an array distribution on the panel (1).

2. A reconfigurable electromagnetic metasurface device according to claim 1, characterized in that: The micropores (11) are in the shape of a trumpet with a thin top and a thick bottom.

3. A reconfigurable electromagnetic metasurface device according to claim 1, characterized in that: Positioning rods (4) are provided at the four corners of the solution pool (2).

4. The reconfigurable electromagnetic metasurface device according to claim 1, characterized in that: The solution is a sodium hexadecyl sulfate solution, and the liquid level is consistent with the height of the protruding strip (5).

5. A reconfigurable electromagnetic metasurface device according to any one of claims 1 to 4, characterized in that: The motor cluster comprises a plurality of micro-nano motors (3), wherein the micro-nano motor (3) comprises a head (31), a middle portion (32) and a tail portion (33), wherein the diameters of the head (31) and the tail (33) are both smaller than the diameter of the microhole (11), and the head (31) and the tail (33) are both asymmetric truncated cone-shaped, the head (31) is covered with ferromagnetic material, and a ferromagnetic spiral (34) is embedded in the micro-nano motor (3).

6. A reconfigurable electromagnetic metasurface device according to claim 5, characterized in that: The ferromagnetic material is nickel-iron material.

7. The reconfigurable electromagnetic metasurface device according to claim 5, characterized in that: The head (31), the middle part (32) and the tail (33) are made of silicon dioxide.

8. A reconfigurable electromagnetic metasurface device according to any one of claims 1 to 4, characterized in that: The rotating magnetic field generating device (7) is an electromagnet or a rotating permanent magnet.

9. A method for using the reconfigurable electromagnetic metasurface device according to any one of claims 1 to 4, characterized in that: The steps include: The first step is to apply equal amplitude and in-phase signals to the ultrasonic crystal oscillator (6) to drive the micro-nano motors (3) to be centrally symmetrically distributed in the solution pool (2), and at the same time adjust the frequency of the ultrasonic crystal oscillator (6) to 1-4 MHz so that the motor cluster density period is smaller than the wavelength of the sound wave; Step 2: Under the premise of maintaining the ultrasonic field drive, the rotating magnetic field is turned on, and the micro-nano motor (3) will stand upright along the direction of the magnetic field line, flip the magnetic field polarity, and change the orientation of the micro-nano motor (3) when standing upright; The third step is to rotate the magnetic field to make the motor move up and down, thereby entering or exiting the micropores (11) of the ultra-thin porous panel (1), so that the electric susceptibility of the surface of the ultra-thin porous panel (1) is graphically distributed, thereby constructing an electromagnetic super surface; The fourth step is that the electromagnetic metasurface selects the wavelength or direction of the reflected wave of the incident electromagnetic wave, and controls the phase and intensity of the ultrasonic signal of the ultrasonic crystal oscillator to control the density distribution pattern of the micro-nano motor (3) cluster, thereby realizing a reconfigurable electromagnetic metasurface.

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