CN211265719U - A Multifunctional Metasurface Based on Solid-State Plasmon Control - Google Patents

Abstract

The utility model discloses a multifunctional metasurface based on solid-state plasma regulation. The metasurface structure comprises, from bottom to top, a bottom metal reflector, a first dielectric layer, a first solid plasma resonance unit, a second Layer dielectric layer, second layer solid-state plasma resonance unit. The solid-state plasma resonance unit is realized by an array composed of PIN units, and the PIN unit array is controlled and excited by the programmable logic array loaded at both ends of the unit, so as to obtain solid-state plasma. By programming and controlling the excitation states of the solid-state plasma resonance units in different regions, the functions of the present invention can be freely switched between the polarization converter and the wave absorber. The utility model has the characteristics of wide frequency band, programmable regulation, flexible design, strong practicability, strong functionality and the like.

Description

A Multifunctional Metasurface Based on Solid-State Plasmon Control

technical field

The utility model relates to a multifunctional metasurface, in particular to a controllable multisurface metasurface based on solid-state plasma, which belongs to the field of solid-state plasma practical technology and microwave device technology.

Background technique

Artificial electromagnetic metasurfaces are a development and extension of new artificial electromagnetic materials. In the process of studying new artificial electromagnetic materials, researchers found that if subwavelength electromagnetic units are arranged on a two-dimensional plane, by designing the structure and arrangement of the units, this plane can affect the propagation of electromagnetic waves. direction and polarization direction. Compared with the new three-dimensional artificial electromagnetic materials, this artificial electromagnetic metasurface has the advantages of low profile, low cost, convenient fabrication, and easy conformation with curved surfaces, so it has a wider application in engineering.

An electromagnetic absorber is a functional structure or device that can absorb the energy of incident electromagnetic waves. Electromagnetic wave absorbers were first widely used in the military field, and mainly focused on radar stealth applications. Scholars from various countries have carried out a lot of work and research on how to design, prepare, test electromagnetic absorbers and improve the performance of electromagnetic absorbers, which has significantly promoted the development of electromagnetic absorbers. In the past, radar wave absorbing materials often have shortcomings such as poor stability, heavy weight and thickness. Therefore, one of the key points of the current research on absorbing materials is to find absorbing materials that can absorb efficiently, have good stability, light weight and thin thickness.

Polarization converter is a device with the function of controlling the polarization direction of electromagnetic waves, and it is a very important device in the application of electromagnetic wave propagation, especially in the fields of nanophotonic devices and advanced sensors. In addition, in the microwave band, polarization converters also play a crucial role in the design of circularly polarized antennas and radomes. The traditional methods for realizing electromagnetic wave polarization regulation are often based on the birefringence effect, and are realized by using dichroic solid-state crystals and twisted nematic liquid crystals. However, these traditional polarization conversion devices all have certain shortcomings. The design process of these traditional polarization control devices is relatively complicated, the thickness of the entire structure is large, and the requirements for materials and processing techniques are high.

Polarization converters and absorbers based on electromagnetic metasurfaces can effectively solve the above problems. The special subwavelength structure and exotic physical properties of metamaterials can not only make a great difference in ultra-thin and miniaturized devices, but also realize broadband after specific design. and reconfigurable requirements. Nowadays, the control performance effect that can be achieved by a single control method is often limited by the external environment and the response of the controllable device to a single physical field, and it is difficult to adapt to the requirements of today's technological development.

Solid-state plasma can solve this problem very well. Solid-state plasma is formed in the semiconductor intrinsic layer by external excitation such as electricity or light. When the external excitation is applied and the carrier concentration in the solid-state plasma reaches a certain value, It exhibits metallic properties. When not excited into a solid-state plasma, it exhibits dielectric properties similar to semiconductors, so it can be useful in tunable/reconfigurable, multi-functional, and multi-physics electromagnetic devices. Respond more fully to diverse electromagnetic environments.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present utility model is to overcome the deficiencies of the prior art, and provide a multifunctional metasurface based on solid-state plasma regulation, which can control the excitation state of the resonance unit composed of solid-state plasma by programming an external logic array. The two functions of energy absorption and cross-polarization conversion in different frequency domains, and further regulate the working frequency band of polarization conversion, and through reasonable parameter optimization, the working range of the absorber can cover most of the C-band and polarized The total operating frequency band of the converter function basically covers the entire C-band and X-band.

The present utility model adopts the following technical solutions to solve the above problems: The utility model provides a multifunctional metasurface based on solid-state plasma regulation, which sequentially includes a bottom metal reflective plate, a first dielectric layer, and a first solid state layer from bottom to top. A plasma resonance unit, a second layer of dielectric layer, a second layer of solid-state plasma resonance unit; the first layer of solid-state plasma resonance unit consists of an Archimedes spiral structure located in the center and two diagonally located first An L-shaped structure is composed of three parts, and the second-layer solid-state plasmonic resonance unit is composed of a reverse Archimedes spiral structure located in the center and two second L-shaped structures located at diagonally opposite corners.

The utility model adopts solid-state plasma as the resonance unit, and the excitation states of different solid-state plasma resonance units are selectively controlled by artificially, and the excitation states of the solid-state plasma resonance units in different regions are controlled by programming, and the metasurface realizes polarization. In addition to the two functions of the converter and the absorber, the working frequency band of the polarization converter can also be adjusted. The metasurface can realize three working states. The first state is a wave absorber, and the working range of the TE mode is 5.87-7.30GHz; the second state is a cross-polarization converter, and the working range is 7.4-12.2GHz; the third state is also a cross-pole converter, but the operating frequency band is shifted to 5.71-8.47GHz. Compared with traditional tunable devices, this structure has the advantages of wide bandwidth, multiple functions, and flexible design, which provides a new idea for the design and development of multi-functional devices.

As a further technical solution of the present utility model, the inner radius of the Archimedes spiral structure of the first-layer solid-state plasma resonance unit is r=0.58mm, and the radius ratio is the ratio of the final radius before and after the spiral to the initial radius, m=5.8, The number of turns N=5, the width w=0.54mm; the two arms of the first L-shaped structure are rectangles with a length e=5.8mm and a width d=2.4mm, and the two arms are respectively f=1mm from the medium boundary.

Further, the reversed Archimedes helix structure is opposite to the first layer Archimedes helix, and other parameters are the same; the two arms of the second L-shaped structure are both length b=7.4mm, width a = 1.7mm rectangle, the two arms are respectively g = 1.4mm from the boundary of the medium.

Further, the solid-state plasma resonance unit is realized by an array composed of PIN units, and there is an isolation layer between the PIN units for isolation; by applying a bias voltage to both ends of the solid-state plasma resonance unit to excite, when the solid-state plasma is not excited, the solid-state plasma is excited. The bulk resonance unit exhibits dielectric properties, that is, an unexcited state; when excited, it exhibits metallic properties, that is, an excited state.

Further, the plasma frequencies of the Archimedes spiral structure and the reverse Archimedes spiral structure are ω _p1 =2.9×10 ¹⁴ rad/s, and the plasma frequencies of the first and second L-shaped structures are ω _p2 =2.2×10 ¹⁵ rad/s, and the collision frequency of all solid-state plasmonic resonance units is ω _c =1.65×10 ¹³ 1/s.

Further, the materials of the two dielectric layers are both FR4, the dielectric constant is 4.3, the loss tangent value is 0.025, the side length of the dielectric layer is p=17mm, and the thickness h=1.8mm.

Further, the material of the underlying metal reflective plate is copper, and the thickness is t=0.1 mm. The thickness of all solid-state plasma resonance units is t=0.1 mm.

Compared with the prior art, the present invention adopts the above technical scheme, and has the following technical effects:

(1) The present utility model is a multifunctional metasurface based on solid-state plasma regulation, and the excitation state of the resonance unit composed of solid-state plasma is programmed and controlled by an external logic array, thereby realizing functional switching (wave absorber-line pole polarization converter) and polarization conversion working frequency band adjustable two purposes. When the electromagnetic wave is vertically incident, three different excitation states can be realized. Through reasonable parameter optimization, we can realize the functions of the absorber (state 1) and the polarization converter (state 2) in the C-band, and further, We can tune to extend the working range of the polarization converter to the X-band (state three).

(2) The utility model has the characteristics of wide frequency band coverage, flexible design, diverse functions, strong practicability and the like.

Description of drawings

Fig. 1 is the top view of the utility model,

Wherein, (a) is a top view of the solid-state plasma resonance unit of the first layer, and (b) is a top view of the solid-state plasma resonance unit of the second layer.

Figure 2 is a side view of the utility model.

FIG. 3 is a perspective view of the utility model.

FIG. 4 is a three-dimensional schematic diagram of three states formed by the utility model.

FIG. 5 is a 3×3 array diagram of the present invention.

FIG. 6 is an absorptivity curve of the state-TE mode when the electromagnetic wave of the present invention is vertically incident.

FIG. 7 is the reflection amplitude curve of the second state when the electromagnetic wave of the present invention is vertically incident (the electric field is along the u-axis and the v-axis respectively).

8 is the reflection phase difference curve of the second state when the electromagnetic wave of the present invention is vertically incident (the electric field is along the u-axis and the v-axis respectively).

FIG. 9 is the reflection amplitude curve of the second state when the electromagnetic wave of the present invention is vertically incident (the electric field is along the y-axis).

FIG. 10 is the reflection amplitude curve of the third state when the electromagnetic wave of the present invention is vertically incident (the electric field is along the u-axis and the v-axis, respectively).

11 is the reflection phase difference curve of the third state when the electromagnetic wave of the present invention is vertically incident (the electric field is along the u-axis and the v-axis respectively).

12 is the reflection amplitude curve of the third state when the electromagnetic wave of the present invention is vertically incident (the electric field is along the y-axis).

Figure 13 is the state two and three polarization conversion rate curves when the electromagnetic wave of the utility model is vertically incident (the electric field is along the y-axis)

Explanation of reference numerals: 1, 2—the second L-shaped solid-state plasma resonance unit, 6, 7—the first L-shaped solid-state plasma resonance unit, 3—the reverse Archimedes spiral solid-state plasma resonance unit, 8— Archimedes spiral solid-state plasma resonance unit, 4—the second FR4 dielectric layer, 5—the first FR4 dielectric layer, 9—metal reflector, 10, 11, 12, 13, 14, 15—plasma excitation source.

Detailed ways

Below in conjunction with the accompanying drawings and specific embodiments, the technical solutions of the present invention are further elaborated:

The utility model is a multifunctional metasurface based on solid-state plasma regulation. The metasurface is formed by periodic arrangement of unit structures. By exciting solid-state plasma resonance units in different regions, the following three states can be generated, as shown in FIG. 4 . Display: state 1, its structural unit includes a bottom metal reflector 9, two FR4 dielectric layers 4, 5, an excited reverse Archimedes spiral solid-state plasma resonance unit 3 and an Archimedes spiral solid-state plasma resonance Unit 8, solid-state plasma excitation sources 10, 11. In state 2, its structural units include a bottom metal reflector 9 , two FR4 dielectric layers 4 and 5 , excited second L-shaped solid-state plasma resonance units 6 and 7 , and solid-state plasma excitation sources 14 and 15 . In the third state, its structural unit includes a bottom metal reflector 9, two FR4 dielectric layers 4, 5, an excited second L-shaped solid-state plasma resonance unit 6, 7, and an excited first L-shaped solid-state plasma resonance unit 1, 2, solid-state plasma excitation sources 12, 13, 14, 15. By selectively programming and exciting different solid-state plasmonic resonance units, the metasurface can realize various functions and switch back and forth freely, and can also achieve the purpose of adjusting the working frequency band under a certain function.

The top view of the first and second-layer solid-state plasmonic resonance units of the metasurface is shown in FIG. 1 , the side view of the metasurface is shown in FIG. 2 , and the (3×3) array diagram of the metasurface is shown in FIG. 5 .

The solid-state plasmon resonance unit is realized by an array of PIN units, each of which is 0.1mm×0.1mm in size. The Drude model is selected to describe the dielectric constant of the solid-state plasma, in which two Archimedes spiral solid-state plasmon resonance units are used. The plasma frequency is ω _p1 =2.9×10 ¹⁴ rad/s, the plasma frequency of the four “L”-shaped solid-state plasma resonance units is ω _p1 =2.2×10 ¹⁵ rad/s, and the plasma frequency of all solid-state plasma resonance units The collision frequency is ω _c =1.65×10 ¹³ 1/s.

The solid-state plasma resonance units 1, 2, 3, 6, 7, and 8 are excited by the plasma excitation sources 10, 11, 15, 14, 12, and 13, respectively. The plasma excitation sources 10, 11, 15, 14, 12, The on-off state of 13 is controlled by programming, as shown in Figure 4.

In the method for generating an electromagnetic metasurface polarization converter based on solid plasma, when the electromagnetic wave (the electric field along the y-axis) is vertically incident, the state is one: the metasurface acts as a wave absorber, and is driven by the excited solid plasma. Caused by the co-working of the resonant units 1 and 2; state 2: The metasurface exhibits the function of a cross-polarization converter, which is caused by the co-working of the excited solid-state plasma resonant units 3 and 4. State 3: The metasurface also functions as a cross-polarization converter, but the operating frequency band is inconsistent with State 2, which is caused by the co-working of the excited solid-state plasmonic resonance units 3, 4, 5, and 6.

The specific parameters of the ultra-metasurface are shown in Table 1.

When only two layers of Archimedes spiral solid-state plasmonic resonance units 3 and 8 are excited, the metasurface can realize the function of a wave absorber, and we define this state as state one. During operation, the electromagnetic wave is perpendicularly incident along the -z direction, and the TE mode is defined as the incident electromagnetic wave with the electric field along the y-axis and the magnetic field along the x-axis. Figure 6 is the absorption curve of the metasurface in the first state TE mode. From Fig. 5 we can see that the absorption rate is greater than 90% in the range of 5.87-7.30GHz, and the relative bandwidth is 21.72%.

When only two second L-shaped solid-state plasmonic resonance units 6, 7 are excited, the function of this metasurface is switched to a linear polarization converter, and we define this state as state two. Figure 7 is the reflection amplitude curve when the electromagnetic wave is incident vertically (the electric field is along the u-axis and the v-axis, respectively) in state 2, wherein the solid line is the reflection coefficient curve r _uu when the u-polarized wave is incident, and the dotted line is the v-polarized wave incident The reflection coefficient curve r _vv when . FIG. 8 is the reflection phase difference curve when the electromagnetic wave is vertically incident (the electric field is along the u-axis and the v-axis, respectively) in the second state. 9 is the reflection amplitude curve when the electromagnetic wave is vertically incident (the electric field is along the y-axis) in state 2, wherein the solid line is the co-polarized reflection amplitude curve r _yy , and the dashed line is the cross-polarized reflection amplitude curve r _xy . In Fig. 7 and Fig. 8, r _uu and r _vv are basically equal and close to 1 at 7.5-12.2GHz, and the reflection phase difference in this frequency band is roughly kept around -180°. It can be seen that the metasurface is in state 2 It has the basic conditions for realizing cross-polarization conversion. Figure 9 further verifies this, we can see that r _xy is much larger than r _yy in the working range, which proves that the y-polarized electromagnetic wave is basically reflected and converted to its cross-polarized wave at 7.5-12.2 GHz, namely x-polarized waves.

When we further excite the two first L-shaped solid-state plasmonic resonance units 1 and 2 on the basis of state 2, the working frequency band of the metasurface to realize cross-polarization conversion can be adjusted to the low-frequency region. We define this state as State three. Fig. 10 is the reflection amplitude curve when the electromagnetic wave is incident vertically (the electric field is along the u-axis and the v-axis, respectively) in the third state. FIG. 11 is the reflection phase difference curve when the electromagnetic wave is vertically incident (the electric field is along the u-axis and the v-axis, respectively) in the third state. FIG. 12 is the reflection amplitude curve when the electromagnetic wave is perpendicularly incident (the electric field is along the y-axis) in state three. Similar to state 2, in Figures 10 and 11, r _uu and r _vv are basically equal and close to 1 at 5.6-8.4 GHz, and the reflection phase difference is roughly kept around ±180°, so the metasurface is in state 3. The basic conditions for realizing cross-polarization conversion are also satisfied. It can be seen from Figure 12 that within 5.6-8.4 GHz, the y-polarized incident wave is basically reflected and converted into an x-polarized wave.

PCR表示反射极化转换率，r_xy表示交叉极化反射系数，r_yy表示同极化反射系数，t_xy表示交叉极化透射系数，t_yy表示同极化透射系数，由于底层为完全金属反射板，所以t_xy＝t_yy＝0。工程上定义，当PCR大于0.9时则可以认为实现高效交叉极化转换。图13是所述超表面在状态二、三下的极化转换率曲线。如图13所示，当所述极化转换器处于状态二(第二L形固态等离子体谐振单元6、7被激励)时，在7.39-12.15GHz内极化转换率基本处在0.9以上。当所述极化转换器处于状态三(第一、二L形固态等离子体谐振单元6、7、1、2被激励)时，在5.58-8.28GHz内极化转换率基本处在0.9以上。综上所述，该极化转换器在切换状态二与状态三时，可以人工调控交叉极化转换的工作频带。For polarization converters, polarization conversion rate is a key indicator to measure the performance of polarization converters. Polarization Conversion Rate Formula

PCR is the reflection polarization conversion ratio, r _xy is the cross-polarization reflection coefficient, r _yy is the co-polarization reflection coefficient, t _xy is the cross-polarization transmission coefficient, and t _yy is the co-polarization transmission coefficient. Since the bottom layer is completely metal reflection plate, so t _xy =t _yy =0. Engineering definition, when PCR is greater than 0.9, it can be considered to achieve efficient cross-polarization conversion. FIG. 13 is the polarization conversion rate curves of the metasurface in states two and three. As shown in FIG. 13 , when the polarization converter is in the second state (the second L-shaped solid-state plasmonic resonance units 6 and 7 are excited), the polarization conversion rate is basically above 0.9 within 7.39-12.15 GHz. When the polarization converter is in state three (the first and second L-shaped solid-state plasmonic resonance units 6, 7, 1, and 2 are excited), the polarization conversion rate is basically above 0.9 within 5.58-8.28 GHz. To sum up, the polarization converter can manually adjust the operating frequency band of the cross-polarization conversion when switching between the second state and the third state.

After a specific design, the utility model can realize the two functions of energy absorption and polarization conversion, and at the same time, the working range of the polarization converter can be adjusted freely according to the needs, so that the metasurface can realize both function switching and function switching. Perform frequency band shifting. The utility model has the characteristics of wide frequency band coverage, various control means, flexible design, strong functionality, strong practicability and the like. The basic principles, main features and advantages of the present invention have been shown and described above. It should be understood by those skilled in the art that the present invention is not limited by the above-mentioned specific embodiments, and the descriptions in the above-mentioned specific embodiments and the specification are only to further illustrate the principle of the present invention, without departing from the spirit and scope of the present invention. , the utility model will also have various changes and improvements, and these changes and improvements all fall within the scope of the claimed utility model. The claimed scope of the present invention is defined by the claims and their equivalents.

Claims (7)

1. a multifunctional metasurface based on solid-state plasma regulation, is characterized in that: from bottom to top, it comprises bottom metal reflector, the first layer of dielectric layer, the first layer of solid-state plasma resonance unit, the second layer of dielectric layer , the second layer of solid-state plasma resonance unit; the first layer of solid-state plasma resonance unit is composed of an Archimedes spiral structure at the center and two first L-shaped structures at diagonally opposite corners. The second-layer solid-state plasmonic resonance unit consists of a reversed Archimedes spiral structure at the center and two second L-shaped structures at diagonally opposite corners. 2. The multifunctional metasurface based on solid-state plasma regulation according to claim 1, characterized in that: the inner radius of the Archimedes spiral structure of the first-layer solid-state plasma resonance unit is r=0.58mm, and the radius ratio is The ratio of the final radius before and after the helical rotation to the initial radius is m=5.8, the number of turns N=5, and the width w=0.54mm; the two arms of the first L-shaped structure are both length e=5.8mm, width d=2.4mm rectangle, the two arms are respectively f=1mm from the boundary of the medium. 3. The multifunctional metasurface based on solid-state plasma regulation according to claim 1, wherein the reversed Archimedes helical structure is opposite to the first-layer Archimedes helix, and the remaining parameters are The same; both arms of the second L-shaped structure are rectangles with a length b=7.4mm and a width a=1.7mm, and the two arms are respectively g=1.4mm from the boundary of the medium. 4. The multifunctional metasurface based on solid-state plasma regulation according to claim 1, wherein the solid-state plasma resonance unit is realized by an array of PIN units, and there is an isolation layer between the PIN units for isolation; By applying a bias voltage to both ends of the solid-state plasma resonance unit to excite, the solid-state plasma resonance unit exhibits dielectric properties when it is not excited, that is, an unexcited state; when it is excited, it exhibits metallic properties, which is an excited state. 5. The multifunctional metasurface based on solid-state plasma regulation according to claim 1, wherein the plasma frequency of the Archimedes helix structure and the reverse Archimedes helix structure is ω _p1 =2.9 ×10 ¹⁴ rad/s, the plasma frequency of the first and second L-shaped structures is ω _p2 =2.2×10 ¹⁵ rad/s, and the collision frequency of all solid-state plasma resonance units is ω _c =1.65×10 ¹³ 1 /s. 6 . The multifunctional metasurface based on solid-state plasma regulation according to claim 1 , wherein the materials of the two dielectric layers are FR4, the dielectric constant is 4.3, the loss tangent is 0.025, and the edge of the dielectric layer is FR4. 7 . Length p=17mm, thickness h=1.8mm. 7. The multifunctional metasurface based on solid-state plasma regulation according to claim 1, characterized in that: the material of the underlying metal reflector is copper, and the thickness is t=0.1 mm; The thickness is t=0.1 mm.

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