CN111490355B - Terahertz chiral metamaterial wave absorber with flexible substrate and manufacturing method - Google Patents
Terahertz chiral metamaterial wave absorber with flexible substrate and manufacturing method Download PDFInfo
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- CN111490355B CN111490355B CN202010206638.6A CN202010206638A CN111490355B CN 111490355 B CN111490355 B CN 111490355B CN 202010206638 A CN202010206638 A CN 202010206638A CN 111490355 B CN111490355 B CN 111490355B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
- H01Q17/008—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems with a particular shape
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
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Abstract
The invention discloses a terahertz chiral metamaterial wave absorber with a flexible substrate and a manufacturing method thereof, wherein in the wave absorber, the wave absorber is formed by a plurality of terahertz chiral metamaterial units which are mutually combined in an array mode, so that the wave absorber has at least two absorption peaks in a terahertz wave band, N-lobe metal chiral structures are symmetrically arranged around the center of the flexible substrate, a first circular ring part is smaller than a complete circular ring divided by N, a cuboid connecting column vertically extends downwards to the lower surface through a first end of the first circular ring part in the clockwise direction, a second circular ring part is smaller than the complete circular ring divided by N, the second circular ring part horizontally extends from the cuboid connecting column to the anticlockwise direction on the lower surface, and the first circular ring part, a rectangular connecting column and the second circular ring part form an integrated Z-shaped structure.
Description
Technical Field
The invention belongs to the technical field of terahertz metamaterials, and particularly relates to a terahertz chiral metamaterial wave absorber with a flexible substrate and a manufacturing method thereof.
Background
Terahertz (THZ) waves generally refer to electromagnetic wave radiation between infrared radiation and microwaves on an electromagnetic spectrum, have a wavelength range of 0.03mm to 3mm and a frequency range of 100GHz to 10THZ, and are also called T rays or submillimeter-wave rays, and the positions of the THZ waves on the electromagnetic spectrum are shown in fig. 1, long wave bands of the THZ waves coincide with millimeter waves, and short wave bands of the THZ waves overlap with infrared rays, so that the THZ waves have some characteristics of microwaves and light waves, but cannot be completely applied to low-frequency microwave theory and high-frequency optical theory. Although terahertz radiation sources are widely visible in nature, terahertz waves have once been an unknown gap in the electromagnetic spectrum, called the terahertz gap, due to the lack of an effective source for emitting terahertz waves and the lack of effective means and devices for detecting terahertz waves. The terahertz wave has the excellent characteristics of low energy, good permeability, large bandwidth and the like.
The metamaterial is an artificial periodic structure with unit structure size smaller than working wavelength, can change the spatial distribution of electromagnetic parameters such as amplitude, phase, polarization and the like in the transmission process of electromagnetic waves, thereby effectively controlling the transmission and local area of the electromagnetic waves, and has the unconventional physical characteristics which are not possessed by natural materials, such as negative refractive index, inverse Doppler effect and the like. The electromagnetic property of the metamaterial is mainly determined by the periodic unit structure of the metamaterial, but not by the intrinsic property of the materials forming the metamaterial, and the dielectric constant and the magnetic permeability of the metamaterial can be manually controlled by adjusting the geometric parameters of the sub-wavelength periodic unit structure, such as the size of a characteristic shape and the period size, so that the research, development and manufacture of electromagnetic wave functional devices are realized. As a brand-new structural material, the metamaterial has unique electromagnetic characteristics, opens up a brand-new research space for the traditional electromagnetic theory, and has profound research significance and wide application prospect in relation to the research of the metamaterial.
Chirality means that the geometric shape of a structure cannot coincide with its mirror image by translation or rotation transformation, and chirality is ubiquitous in nature, such as proteins, DNA, quartz crystals, and the like, and has important roles in the fields of optics, biology, chemistry, medicine, life sciences, and the like. The chiral metamaterial is a branch of the metamaterial, wherein chirality describes the geometric shape characteristic of the metamaterial, and means that the geometric shape of the metamaterial cannot be coincided with the mirror image of the metamaterial through translation or rotation. The chiral metamaterial has a peculiar electromagnetic property due to the particularity of a geometric structure of the chiral metamaterial, and through electromagnetic waves of the chiral material, both electric field and magnetic field components of the chiral metamaterial can induce magnetic polarization and electric polarization, namely, a cross coupling effect is generated, so that left-hand circularly polarized waves and right-hand circularly polarized waves have different refractive indexes after passing through the chiral material, phase delay is generated between the left-hand circularly polarized waves and the right-hand circularly polarized waves, strong optical rotation is shown, and in addition, the electromagnetic waves can generate large circular dichroism after passing through the chiral material. The absorption of electromagnetic waves can be realized by utilizing the chiral metamaterial, and the chiral absorption shows different responses to left-handed circularly polarized waves (LCP) and right-handed circularly polarized waves (RCP) and can be divided into selective absorption and non-selective absorption. The selective absorption means that when LCP/RCP electromagnetic waves are incident to the surface of the chiral metamaterial, only a certain chiral wave is efficiently absorbed, and the non-selective absorption means that the chiral metamaterial shows the same degree of absorption on LCP and RCP.
In the prior art, a flexible wave absorber composed of metal-medium-metal is characterized in that a top layer of the wave absorber is a frequency selective surface formed by periodically arranging metal wafers, a middle layer of the wave absorber is a flexible medium, and a lower layer of the wave absorber is a frequency selective surface formed by periodically arranging annular grooves on a metal film bottom plate. The structure has the characteristic of flexibility, and can be deformed such as bent to adapt to different application occasions. However, the structures of the upper layer and the lower layer of the wave absorber are different, so that the wave absorber only has the wave absorbing function in single-side transmission, and the wave absorber only has a single absorption peak in the working frequency band, which limits the practical application range of the wave absorber. A double-layer chiral metamaterial wave absorber is composed of metal and a medium substrate. The metal part forms a chiral structure, the top layer and the bottom layer of the structure are communicated, when left-hand circularly polarized waves are incident, strong current is induced on the surface of the metal wire, and when right-hand circularly polarized waves are incident, the current density of the metal surface is obviously weaker than that of the left-hand circularly polarized waves, mutual coupling can be ignored, namely, the right-hand circularly polarized waves can pass through the structure with low loss, and the left-hand circularly polarized waves are perfectly absorbed due to strong mutual resonance. The wave absorber is a selective chiral wave absorber and can realize selective left-handed absorption and right-handed transmission. But the structure has narrow absorption band in the absorption frequency band and only has a single absorption peak, and the inflexible characteristic also limits the practical application of the structure.
At present, an important application of the electromagnetic metamaterial is to develop a wave absorber with frequency selectivity. One common method is to design a typical metal-dielectric-metal three-layer wave absorber structure. Landy et al originally proposed the electromagnetic wave absorber with three-layer structure, the top layer of the wave absorber structure is a double-opening resonance ring, the middle layer is a dielectric layer, and the bottom layer is a metal strip. When electromagnetic waves are incident perpendicular to the plane of the top layer, the metal thin films of the top layer and the bottom layer generate electric response, meanwhile, reverse parallel current between the open resonant ring and the metal strip of the bottom layer generates magnetic response (Lorentz magnetic response), the two responses generate strong coupling effect with the electromagnetic waves at resonant frequency, so that the electromagnetic waves are strongly absorbed, the absorption peak value can reach 88%, the perfect absorption is approximate, but the structure cannot be practically applied due to narrow absorption bandwidth. Therefore, the subsequent metamaterial wave absorber design basically adopts the scheme of the three-layer structure. In order to achieve the electrical response and the magnetic response when electromagnetic waves enter, the top layer and the bottom layer of the three-layer wave absorber are often designed into different geometric structures, so that the wave absorbing effect can be generated only on the electromagnetic waves entering from one direction, and double-sided wave absorption cannot be realized. In broadening the absorption bandwidth, the common approach is to superimpose, tile or nest on the common structure. For example, the wave absorber of the pyramid metamaterial wave absorber proposed by Lei et al has a structure comprising a plurality of thin films in which aluminum and germanium alternately appear, the wave absorber can remarkably expand the absorption bandwidth, but the geometrical thickness of the wave absorber is remarkably increased due to the multi-layer structure, and the light and thin requirements of the wave absorber cannot be met. The metamaterial wave absorber can be widely applied to the fields of sensing, radar, imaging and the like, has the characteristic of flexibility and deformability, can be better attached to a molded surface or more suitable for application occasions, and obtains better wave absorbing effect, but the existing metamaterial wave absorber is generally inflexible.
The above information disclosed in this background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides the terahertz chiral metamaterial wave absorber with the flexible substrate and the manufacturing method thereof, wherein the terahertz chiral metamaterial wave absorber with the flexible substrate displays two different high-efficiency absorption peaks in corresponding terahertz wave bands. Due to the structural particularity, the wave absorber has the same wave absorbing property when electromagnetic waves are incident in the forward direction and in the reverse direction, so that the wave absorber can be applied to the field needing double-sided wave absorption. The wave absorber adopts a flexible substrate and has the characteristics of lightness and thinness, and can be bent and deformed according to specific application requirements in practical application so as to be well attached to various curved surface targets in a conformal manner, thereby obtaining good use effect and further expanding the application range of the structure.
The purpose of the invention is realized by the following technical scheme.
A terahertz chiral metamaterial wave absorber with a flexible substrate is formed by a plurality of terahertz chiral metamaterial units which are mutually combined in an array mode, so that the wave absorber has at least two absorption peaks in a terahertz wave band, and the terahertz chiral metamaterial unit comprises: a flexible substrate having an upper surface and a lower surface, the upper surface having a height H from the lower surface.
N-lobe metal chiral structures which are symmetrically arranged around the center of the flexible substrate, wherein N is a natural number more than or equal to 2, and the metal chiral structures formed by chiral metamaterials comprise.
A first annular portion less than one-nth of a complete annulus, the first annular portion disposed horizontally on the upper surface with an inner radius of R1 and an outer radius of R2 and a thickness of h.
The cuboid spliced pole, it is via clockwise on the first end of first ring part vertically downwardly extending to the lower surface, the length of cuboid spliced pole is the difference between R2 and R1, and the width is B, and the height is H.
The second ring part is smaller than one N of complete rings, the lower surface of the second ring part horizontally extends towards the anticlockwise direction from the cuboid connecting column, the inner circle radius of the second ring part is equal to that of the first ring part, the outer circle radius of the second ring part is equal to that of the first ring part, the thickness of the second ring part is equal to that of the first ring part, and the first ring part, the rectangular connecting column and the second ring part form an integrated Z-shaped structure.
In the terahertz chiral metamaterial wave absorber with the flexible substrate, N first ring parts and N second ring parts of the N-lobe metal chiral structure are in angle dislocation relative to the flexible substrate.
In the terahertz chiral metamaterial wave absorber with the flexible substrate, a cuboid connecting column extends downwards vertically to the lower surface through the first end of the first circular ring part in the anticlockwise direction, and a second circular ring part extends horizontally towards the clockwise direction from the lower surface of the cuboid connecting column.
In the terahertz chiral metamaterial wave absorber with the flexible substrate, the N-lobe metal chiral structures are arranged around the center of the unit flexible substrate symmetrically.
In the terahertz chiral metamaterial wave absorber with the flexible substrate, the period size of a terahertz chiral metamaterial unit is L, the flexible substrate of the unit is square, and the side length of the flexible substrate is L.
In the terahertz chiral metamaterial wave absorber with the flexible substrate, the distance between the adjacent first circular ring parts is S, and the distance between the adjacent second circular ring parts is S.
In the terahertz chiral metamaterial wave absorber with the flexible substrate, the relative rotation angle between the N-lobe metal chiral structure and the flexible substrate is 0-360 DEG/N.
In the terahertz chiral metamaterial wave absorber with the flexible substrate, the metal chiral structure is made of gold, silver, copper, aluminum, zinc, nickel, tungsten, iron, chromium, titanium, platinum and alloys or polymers and compounds thereof.
In the terahertz chiral metamaterial wave absorber with the flexible substrate, the flexible substrate comprises a flexible film, the upper surface and the lower surface of the flexible film are horizontal, and the flexible film comprises a polytetrafluoroethylene film, a polyimide film, a polystyrene film, a benzocyclobutene film, a parylene film, a polypropylene film, a silicon dioxide film or a composite of the polytetrafluoroethylene film, the polyimide film, the polystyrene film and the benzocyclobutene film.
According to another aspect of the invention, the method for manufacturing the terahertz chiral metamaterial wave absorber with the flexible substrate comprises the following steps.
The first step is as follows: a flexible film of H thickness was obtained.
The second step is as follows: and cutting a rectangular through hole on the flexible film according to the position and the shape of the cuboid connecting column by adopting ion beam etching or laser cutting.
The third step: respectively coating positive photoresist on two sides of the film, exposing a rectangular through hole pattern on one side, removing the photoresist on the exposed part after developing to expose the rectangular through hole, filling the rectangular through hole with electron beam evaporation or magnetron sputtering coating deposition metal to form a cuboid connecting column, and removing the photoresist on the two sides of the film.
The fourth step: coating positive photoresist on the upper surface of the film, then exposing the first circular ring part structure, developing to remove the photoresist on the exposed part, depositing the first circular ring part structure with the thickness of h by using electron beam evaporation or magnetron sputtering coating, and removing the photoresist to obtain the structure of the first circular ring part structure connected with the cuboid connecting column.
The fifth step: and repeating the fourth step on the lower surface of the film to obtain a second circular ring part structure, wherein the first circular ring part, the rectangular connecting column and the second circular ring part form an integrated Z-shaped structure.
The invention has the following beneficial effects:
aiming at the problems that the existing metamaterial wave absorber can only absorb wave unidirectionally, only has a single absorption peak, has narrow absorption peak, is inflexible and cannot be flexibly applied to practice and the like, the terahertz chiral double-sided metamaterial wave absorber with the flexible substrate displays two different high-efficiency absorption peaks in corresponding terahertz wave bands. Due to the structural particularity, the wave absorber has the same wave absorbing property when electromagnetic waves are incident in the forward direction and in the reverse direction, so that the wave absorber can be applied to the field needing double-sided wave absorption. The wave absorber adopts a flexible substrate and has the characteristics of lightness and thinness, and can be bent and deformed according to specific application requirements in practical application so as to be well attached to various curved surface targets in a conformal manner, thereby obtaining good use effect and further expanding the application range of the structure.
The above description is only an overview of the technical solutions of the present invention, and in order to make the technical means of the present invention more clearly apparent, and to make the implementation of the content of the description possible for those skilled in the art, and to make the above and other objects, features and advantages of the present invention more obvious, the following description is given by way of example of the specific embodiments of the present invention.
Drawings
Various other advantages and benefits of the present invention will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. It is obvious that the drawings described below are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort. Also, like parts are designated by like reference numerals throughout the drawings.
In the drawings:
FIG. 1 is a schematic illustration of the location of a terahertz wave in the electromagnetic spectrum;
FIG. 2 is a schematic structural diagram of a terahertz chiral metamaterial wave absorber of a flexible substrate according to one embodiment of the invention;
FIG. 3 is a structural schematic diagram of a wave absorbing unit of a terahertz chiral metamaterial wave absorber with a flexible substrate according to one embodiment of the invention;
FIG. 4 is a schematic structural geometry diagram of a terahertz chiral metamaterial wave absorber of a flexible substrate according to one embodiment of the invention;
FIG. 5 is a graph of an absorption rate of a terahertz chiral metamaterial wave absorber of a flexible substrate according to one embodiment of the invention;
FIG. 6 is a schematic step diagram of a manufacturing method of a terahertz chiral metamaterial wave absorber of a flexible substrate according to one embodiment of the invention;
fig. 7a to 7h are schematic process flow diagrams of a manufacturing method of a terahertz chiral metamaterial wave absorber with a flexible substrate according to an embodiment of the invention.
The invention is further explained below with reference to the figures and examples.
Detailed Description
Specific embodiments of the present invention will be described in more detail below with reference to fig. 1 to 7. While specific embodiments of the invention are shown in the drawings, it should be understood that the invention may be embodied in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
It should be noted that certain terms are used throughout the description and claims to refer to particular components. As one skilled in the art will appreciate, various names may be used to refer to a component. This specification and claims do not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to. The description which follows is a preferred embodiment of the invention, but is made for the purpose of illustrating the general principles of the invention and not for the purpose of limiting the scope of the invention. The scope of the present invention is defined by the appended claims.
For the purpose of facilitating understanding of the embodiments of the present invention, the following description will be made by taking specific embodiments as examples with reference to the accompanying drawings, and the drawings are not to be construed as limiting the embodiments of the present invention.
For better understanding, as shown in fig. 2 to 3, a terahertz chiral metamaterial wave absorber of a flexible substrate is formed by a plurality of terahertz chiral metamaterial units 1 combined with each other in an array, so that the wave absorber has at least two absorption peaks in a terahertz wave band, the terahertz chiral metamaterial unit 1 includes:
a unit flexible substrate 2 having an upper surface and a lower surface, the upper surface having a height H to the lower surface.
N-lobe metal chiral structures 3 which are symmetrically arranged around the center of the flexible substrate 2, wherein N is a natural number greater than or equal to 2, and the metal chiral structures 3 formed by chiral metamaterials comprise.
A first annular portion 4, which is less than a full circle of one-nth, said first annular portion 4 being arranged horizontally on the upper surface with an inner circular radius R1 and an outer circular radius R2, and having a thickness h.
A cuboid connecting column 5 vertically extending downwards to the lower surface via the first end of the first circular ring part 4 in the clockwise direction, the cuboid connecting column 5 having a length of R2 and R1 difference, a width of B and a height of H.
The second ring part 6 is smaller than one N times of complete rings, the second ring part 6 extends horizontally towards the anticlockwise direction from the cuboid connecting column 5 on the lower surface, the inner circle radius of the second ring part is equal to that of the first ring part, the outer circle radius of the second ring part is equal to that of the first ring part, the thickness of the second ring part is equal to that of the first ring part, and the first ring part 4, the rectangular connecting column and the second ring part 6 form an integrated Z-shaped structure.
The wave absorber can realize the high-efficiency absorption of electromagnetic waves at two different frequency points in the corresponding terahertz wave band. Due to the structural particularity of the wave absorber, the wave absorber has the same wave absorbing characteristic when in forward incidence and reverse incidence, so that the wave absorber can be applied to the field needing double-sided wave absorption. The wave absorber is easy to bend and deform due to the characteristics of flexibility, thinness and thinness, can be well conformal to various curved surface targets, and further expands the application range of the structure.
In the preferred embodiment of the terahertz chiral metamaterial wave absorber with the flexible substrate, N first ring portions 4 and four second ring portions 6 of the N-lobe metal chiral structure 3 are angularly misaligned relative to the unit flexible substrate 2.
In the preferred embodiment of the terahertz chiral metamaterial wave absorber with the flexible substrate, the cuboid connecting column 5 extends vertically downwards to the lower surface through the first end of the first annular part 4 in the counterclockwise direction, and the second annular part 6 extends horizontally from the cuboid connecting column 5 in the clockwise direction on the lower surface.
In the preferred embodiment of the terahertz chiral metamaterial wave absorber with the flexible substrate, the N-lobe metal chiral structures 3 are four-lobe metal chiral structures 3, and are arranged around the center of the unit flexible substrate 2 in a symmetrical manner.
In the preferred embodiment of the terahertz chiral metamaterial wave absorber with the flexible substrate, the periodic size of the terahertz chiral metamaterial unit 1 is L, the unit flexible substrate 2 is square, and the side length of the unit flexible substrate is L.
In a preferred embodiment of the terahertz chiral metamaterial wave absorber with the flexible substrate, the distance between the adjacent first circular ring portions 4 is S, and the distance between the adjacent second circular ring portions 6 is S.
In the preferred embodiment of the terahertz chiral metamaterial wave absorber with the flexible substrate, the relative rotation angle between the N-lobe metal chiral structure 3 and the flexible substrate 2 is 0-90 degrees.
In a preferred embodiment of the terahertz chiral metamaterial wave absorber with the flexible substrate, the metal chiral structure 3 is made of gold, silver, copper, aluminum, zinc, nickel, tungsten, iron, chromium, titanium, platinum, and alloys or polymers and compounds thereof.
In the preferred embodiment of the terahertz chiral metamaterial wave absorber with the flexible substrate, the flexible substrate 2 comprises a flexible film, the upper surface and the lower surface of the flexible film are horizontal, and the flexible film comprises a polytetrafluoroethylene film, a polyimide film, a polystyrene film, a benzocyclobutene film, a parylene film, a polypropylene film, a silicon dioxide film or a composite thereof.
In order to further understand the invention, the structural schematic diagram of the metamaterial wave absorber is shown in fig. 2, aiming at the conditions that the existing common metamaterial wave absorber only has a single absorption peak and the absorption bandwidth of the wave absorber is narrow, or the thickness of the wave absorber is obviously increased for increasing the absorption bandwidth, the wave absorber cannot be applied to the field needing double-sided wave absorption, the practical use of the wave absorber is limited by the inflexible characteristic, and the like. In one embodiment, the metamaterial unit 1 is composed of a four-petal chiral structure 3 made of metal and a flexible substrate 2, each petal of the metal chiral structure 3 is composed of two partial thin circular rings slightly smaller than a quarter of the circular ring and a rectangular connecting column 5 connecting the partial thin circular rings, and the two partial thin circular rings are respectively located on the upper surface and the lower surface of the flexible substrate 2 and form a Z-like shape with the rectangular connecting column 5. The angular separation between the four-lobed metal chiral structures 3 is 90 °. The chiral structure 3 is positioned at the center of the square flexible substrate 2, and the thickness of the flexible substrate 2 is the same as the height of the cuboid connecting column 5. The specific geometric dimension of the structure to be determined is shown in fig. 4, and the geometric dimension of the structure includes: the length, the width and the height of the cuboid connecting column 5 are (R2-R1) and B, H respectively, the thickness of the flexible substrate 2 is H, and the periodic dimension of the unit structure is L.
To better illustrate the characteristics of the present invention, a specific example is given, in which the inner circle radius R1 is 22 μm, the outer circle radius R2 is 30 μm, the ring height H is 0.5 μm, the spacing S between adjacent rings is 3 μm, the length, width and height of the rectangular parallelepiped connecting pillar 5 are (R2-R1) 8 μm, B is 2 μm, and H is 12 μm, the thickness of the flexible substrate 2 is H12 μm, and the unit structure period size L is 64 μm. Wherein the chiral metal structure is excellent conductor gold, and the flexible substrate 2 is flexible medium Polytetrafluoroethylene (PTFE) with loss. The structure was subjected to wave-absorbing simulation using the electromagnetic simulation software CST study, and the resulting absorption rate curve is shown in fig. 5. As can be seen from the figure, the absorption rate curves of the forward incidence and the reverse incidence are completely overlapped, and the metamaterial wave absorber achieves the effect of double-sided wave absorption. The wave absorber has two absorption peaks, 96.88% of absorption is achieved at 1.932THz, 96.07% of absorption is achieved at 4.361THz, and efficient absorption of two different frequency points is achieved.
It should be noted that the specific dimensions and materials given in this example are only one embodiment of the invention. The specific geometrical dimensions of the metamaterial unit 1 structure can be determined by the frequency points to be absorbed according to the specific implementation situation. This embodiment shows a case where the relative rotation angle of the chiral structure 3 and the unit flexible substrate 2 is zero, and the relative angle may be any angle from 0 ° to 90 °. For chiral metal structures, the material should be a good conductor, including gold (Au), silver (Ag), copper (Cu), aluminum (A1), and zincMetals such as (Zn), nickel (Ni), tungsten (W), iron (Fe), chromium (Cr), titanium (Ti), platinum (Pt), or alloys, polymers, and compounds containing the above metals. For the unit flexible substrate 2, a material thereof may be selected as a certain flexible film, such as a Polytetrafluoroethylene (PTFE) film, a Polyimide (PI) film, a Polystyrene (PS) film, a benzocyclobutene (BCB) film, a Parylene film (Parylene), a polypropylene (PP) film, a silicon dioxide (SiO) film2) Film, etc. or a composite thereof.
In one embodiment, the height H from the upper surface to the lower surface of the unit flexible substrate is a lossy medium, and higher absorptivity can be obtained when H is greater than 10 micrometers (μm); if the flexible metamaterial wave absorber is light and thin, H can be smaller than 15 micrometers (mum). Therefore, if the absorption rate is high and the light weight is kept, the value of H can be in the range of 10-15 micrometers (mum);
in addition, typically, the inner circle radius R1 of the circular ring, the outer circle radius R2 and the metamaterial period size L can be obtained according to the principle that R1 < R2 < L, and the value ranges of the parameters are selected according to the terahertz frequency band targeted by the wave absorber, for example:
the value range of R2 is 20-40 micrometers (mum), and the value of R1 is as follows: (R2-R1)/R2 is selected from 0.2-0.3, and the value of L is determined according to the following formula: L/2-R2 is between 1-4 microns (μm);
furthermore, as a rule of thumb, the ring thickness h is typically taken to be 0.5 micrometers (μm); the width B of the rectangular connecting column ranges from 1 micron to 3 microns (mum). The spacing S between adjacent rings ranges from 2 to 5 micrometers (μm).
As shown in fig. 6, a method for manufacturing a terahertz chiral metamaterial wave absorber with a flexible substrate includes the following steps.
First step S1: a flexible film of H thickness was obtained.
Second step S2: and cutting a rectangular through hole on the flexible film according to the position and the shape of the cuboid connecting column 5 by adopting ion beam etching or laser cutting.
Third step S3: respectively coating positive photoresist on two sides of the film, exposing a rectangular through hole pattern on one side, removing the photoresist on the exposed part after developing to expose the rectangular through hole, filling the rectangular through hole with electron beam evaporation or magnetron sputtering coating deposition metal to form a cuboid connecting column 5, and removing the photoresist on the two sides of the film.
Fourth step S4: coating positive photoresist on the upper surface of the film, then exposing the first circular ring part structure, developing to remove the photoresist on the exposed part, depositing the first circular ring part structure with the thickness of h by using electron beam evaporation or magnetron sputtering coating, and removing the photoresist to obtain the structure of connecting the first circular ring part structure with the cuboid connecting column 5.
Fifth step S5: and repeating the fourth step on the lower surface of the film to obtain a second circular ring part structure, wherein the first circular ring part, the rectangular connecting column and the second circular ring part form an integrated Z-shaped structure.
In a preferred embodiment, as shown in fig. 7, the method comprises:
as shown in fig. 7a, the first step: and obtaining the flexible medium film with the corresponding thickness according to the designed thickness H of the wave absorber medium. The second step is that: and cutting a rectangular through hole on the flexible film by adopting ion beam etching or high-precision laser cutting according to the position and shape information of the rectangular connecting column of the metamaterial wave absorber.
The third step: as shown in fig. 7b, positive photoresist is coated on both sides of the thin film, a rectangular via hole pattern is exposed on one side, as shown in fig. 7c, the photoresist on the exposed portion is removed after development to expose the rectangular via hole, then the rectangular via hole is filled with metal by deposition methods such as electron beam evaporation or magnetron sputtering coating to form a rectangular via hole, as shown in fig. 7d, and finally the photoresist on both sides of the thin film is removed.
The fourth step: as shown in fig. 7e, a positive photoresist is coated on one side of the film embedded into the metal rectangular connecting post, then a single-side metal thin circular ring structure is exposed, the photoresist of the exposed part is removed by development, as shown in fig. 7f, a metal thin circular ring area is exposed on the film, a metal thin circular ring structure with the thickness of designed thickness h is deposited by using a deposition method such as electron beam evaporation or magnetron sputtering coating, and as shown in fig. 7g, the photoresist is removed, and then a structure that the single-side metal thin circular ring is connected with the rectangular metal connecting post is obtained.
The fifth step: as shown in fig. 7h, repeating the fourth step (using the same mask during exposure) on the other surface of the film to obtain a metal thin circular ring structure on the other surface, and obtaining a double-sided metal thin circular ring and a rectangular connecting column structure connecting the double-sided metal thin circular ring structure, so as to complete the manufacturing of the whole terahertz metamaterial wave absorber.
The metamaterial wave absorber structure consisting of the four-lobe chiral thin circular ring structure and the flexible medium has completely the same geometric configuration in the forward direction and the reverse direction, so that the wave absorber has the characteristic of double-sided wave absorption, the four-lobe metal chiral structure 3 has completely the same geometric configuration on the upper surface and the lower surface, and when electromagnetic waves are transmitted in the forward direction and in the reverse direction, the wave absorber has the same wave absorption characteristic and has two efficient absorption peaks in a terahertz frequency band. The metamaterial wave absorber adopts the flexible substrate 2, so that the metamaterial wave absorber can be bent and stretched to deform to adapt to different conditions in practical application, is convenient to conform to a molded surface or be attached to the molded surface, and can be conveniently and flexibly applied to practical working occasions due to the characteristics. The metamaterial wave absorber is manufactured in a micro-nano manufacturing process in a photoetching, deposition and other process flow steps with high precision.
Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above-described embodiments and application fields, and the above-described embodiments are illustrative, instructive, and not restrictive. Those skilled in the art, having the benefit of this disclosure, may effect numerous modifications thereto without departing from the scope of the invention as defined by the appended claims.
Claims (7)
1. A terahertz chiral metamaterial wave absorber with a flexible substrate is characterized in that the wave absorber is formed by a plurality of terahertz chiral metamaterial units which are mutually combined in an array mode, so that the wave absorber has at least two absorption peaks in a terahertz wave band, the terahertz chiral metamaterial units comprise,
the unit flexible substrate is provided with an upper surface and a lower surface, the height from the upper surface to the lower surface is H, the period size of the terahertz chiral metamaterial unit is L, the unit flexible substrate is square, the side length of the unit flexible substrate is L,
n-lobe metal chiral structures which are arranged around the center of the unit flexible substrate symmetrically, N is a natural number which is more than or equal to 2, the metal chiral structures formed by chiral metamaterials comprise,
a first ring portion of less than one-nth complete ring disposed horizontally on the upper surface with an inner radius of R1 and an outer radius of R2 and a thickness of h,
a rectangular parallelepiped connecting pillar extending vertically downward to a lower surface through a first end of the first annular ring portion in a clockwise direction, the rectangular parallelepiped connecting pillar having a length of a difference between R2 and R1, a width of B, and a height of H,
the second ring part is smaller than one-N complete rings, the second ring part horizontally extends from the position of the cuboid connecting column towards the counterclockwise direction on the lower surface, the inner circle radius of the second ring part is equal to that of the first ring part, the outer circle radius of the second ring part is equal to that of the first ring part, and the thickness of the second ring part is equal to that of the first ring part, wherein the first ring part, the rectangular connecting column and the second ring part form an integrated Z-shaped structure, the N first ring parts and the N second ring parts of the N-petal metal chiral structure are angularly staggered relative to the unit flexible substrate, the distance between the adjacent first ring parts is S, the distance between the adjacent second ring parts is S, and R1 is smaller than R2 and smaller than L.
2. The terahertz chiral metamaterial wave absorber with the flexible substrate as claimed in claim 1, wherein a rectangular parallelepiped connecting column extends vertically downward to a lower surface via a first end of the first circular ring portion in a counterclockwise direction, and a second circular ring portion extends horizontally from the rectangular parallelepiped connecting column to a clockwise direction at the lower surface.
3. The terahertz chiral metamaterial wave absorber of the flexible substrate as claimed in claim 1, wherein the N-lobe metal chiral structures are arranged symmetrically around the center of the unit flexible substrate.
4. The terahertz chiral metamaterial wave absorber of the flexible substrate as claimed in claim 1, wherein the relative rotation angle between the N-lobe metal chiral structure and the flexible substrate is 0 ° to 360 °/N.
5. The terahertz chiral metamaterial wave absorber of the flexible substrate as claimed in claim 1, wherein the metal chiral structure is made of gold, silver, copper, aluminum, zinc, nickel, tungsten, iron, chromium, titanium, platinum, and alloys or polymers and compounds thereof.
6. The terahertz chiral metamaterial wave absorber with the flexible substrate as claimed in claim 1, wherein the flexible substrate comprises a flexible film, the upper surface and the lower surface of the flexible film are horizontal, and the flexible film comprises a polytetrafluoroethylene film, a polyimide film, a polystyrene film, a benzocyclobutene film, a parylene film, a polypropylene film, a silicon dioxide film or a composite thereof.
7. A manufacturing method of the terahertz chiral metamaterial wave absorber of the flexible substrate as claimed in any one of claims 1 to 6, comprising the following steps,
the first step is as follows: obtaining a flexible thin film with the thickness of H;
the second step is as follows: cutting a rectangular through hole on the flexible film according to the position and the shape of the cuboid connecting column by adopting ion beam etching or laser cutting;
the third step: respectively coating positive photoresist on two sides of the film, exposing a rectangular through hole pattern on one side, removing the photoresist on the exposed part after developing to expose the rectangular through hole, filling the rectangular through hole with deposited metal by using electron beam evaporation or magnetron sputtering coating to form a cuboid connecting column, and removing the photoresist on the two sides of the film;
the fourth step: coating positive photoresist on the upper surface of the film, exposing the first ring part structure, developing to remove the photoresist on the exposed part, depositing the first ring part structure with the thickness of h by using electron beam evaporation or magnetron sputtering coating, removing the photoresist to obtain a structure of the first ring part structure connected with the cuboid connecting column,
the fifth step: and repeating the fourth step on the lower surface of the film to obtain a second circular ring part structure, wherein the first circular ring part, the rectangular connecting column and the second circular ring part form an integrated Z-shaped structure.
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Non-Patent Citations (4)
| Title |
|---|
| Optical properties of a three-dimensional chiral metamaterial;Guo Juan-Juan等;《Chinese Physics B》;20171215;第26卷(第12期);第124211-1-124211-5页 * |
| Wide angle and polarization independent chiral metamaterial absorber;Bingnan Wang等;《PHYSICAL REVIEW》;20090730;第1-10页 * |
| 基于柔性超材料的毫米波多频吸波器;张勇;《CNKI优秀硕士学位论文全文库》;20170831;第31-43页 * |
| 手性超材料圆极化波吸收特性研究进展;汪丽丽等;《材料导报》;20190210(第3期);第500-509页 * |
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