Terahertz broadband modulator based on 3D printing technology and manufacturing method thereof

Abstract

The present invention discloses a terahertz broadband modulator based on 3D printing technology and a manufacturing method thereof. The modulator includes a field source and a control device. The control device includes a substrate, a structural layer arranged on the upper layer of the base, an active layer arranged on the upper layer of the structural layer, a protective layer arranged on the upper layer of the active layer, and a first electrode layer and a second electrode layer respectively arranged on both sides of the protective layer and in contact with the active layer; the structural layer is made by 3D printing technology of surface projection stereoscopic light curing; the structural layer is composed of a plurality of hollow cubes arranged closely; the upper end face and four side faces of the hollow cube are provided with through holes connected to the internal cavity; a built-in thin film layer is laid in the internal cavity of the hollow cube; and a connecting hole corresponding to the through hole arranged on the upper end face of the hollow cube in the structural layer is provided on the active layer. The above modulator, using sub-wavelength hollow cubes, can realize active control of terahertz based on light field, electric field or magnetic field, greatly improving the modulation effect of terahertz waves.

Description

Technical Field

[0001] The present invention relates to the technical field of terahertz wave modulation, and in particular to a terahertz broadband modulator based on 3D printing technology and a manufacturing method thereof. Background Art

[0002] Terahertz (THz) waves usually refer to electromagnetic waves with a frequency range of 0.1 to 10.0 THz and a wavelength of 0.03 to 3 mm, which is exactly between microwaves and infrared light. Compared with other bands such as microwaves and infrared light, THz waves have many unique properties, such as low photon energy, high penetration, broadband, and strong coherence. These characteristics make THz waves have broad application prospects in the fields of communications, THz imaging sensing, biomedicine, and security detection.

[0003] In the field of terahertz technology, terahertz modulation devices are the core components for applying terahertz technology, which can realize the regulation of the amplitude, phase, polarization, etc. of terahertz waves. However, the terahertz modulators in the prior art methods are all used to realize passive modulation, and cannot effectively realize the active modulation of terahertz waves. As a result, the effect of modulating terahertz waves is poor and the modulation efficiency is low. Therefore, the terahertz modulators in the prior art methods have the problem of poor modulation effect on terahertz waves. Summary of the invention

[0004] The embodiment of the present invention provides a terahertz broadband modulator based on 3D printing technology and a manufacturing method thereof, aiming to solve the problem of poor modulation effect of terahertz waves existing in the terahertz modulator in the prior art method.

[0005] In the first aspect, an embodiment of the present invention provides a terahertz broadband modulator based on 3D printing technology, wherein the terahertz broadband modulator includes a field source and a control device, the control device includes a substrate, a structural layer arranged on the upper layer of the base, an active layer arranged on the upper layer of the structural layer, a protective layer arranged on the upper layer of the active layer, and a first electrode layer and a second electrode layer respectively arranged on both sides of the protective layer and in contact with the active layer; the first electrode layer and the second electrode layer are both in contact with the upper end surface of the active layer; the structural layer is obtained by 3D printing technology of surface projection stereolithography; the structural layer is composed of a plurality of hollow cubes arranged closely; the upper end surface and four side surfaces of the hollow cube are provided with through holes connected to the internal cavity; the internal cavity of each of the hollow cubes is paved with a built-in thin film layer; the active layer is provided with a connecting hole corresponding to the through hole provided on the upper end surface of the hollow cube in the structural layer; the field source generates an external field and acts on the surface of the control device, and the active control of the terahertz wave is realized by adjusting the intensity of the field source.

[0006] The terahertz broadband modulator based on 3D printing technology, wherein the diameter of the through hole is 0.3 to 0.7 times the side length of the hollow cube.

[0007] The terahertz broadband modulator based on 3D printing technology, wherein the wall thickness of the hollow cube is 0.08 to 0.15 times the side length of the hollow cube.

[0008] The terahertz broadband modulator based on 3D printing technology, wherein the overall shape of the structural layer is a square.

[0009] The terahertz broadband modulator based on 3D printing technology, wherein the ratio between the side length of the hollow cube and the wavelength of the terahertz wave modulatable by the terahertz broadband modulator is 0.35 to 0.8.

[0010] The terahertz broadband modulator based on 3D printing technology, wherein the substrate is a silicon substrate or a silicon oxide substrate.

[0011] In the terahertz broadband modulator based on 3D printing technology, the protective layer is a silicon oxide layer or a hexagonal boron nitride layer.

[0012] The terahertz broadband modulator based on 3D printing technology is characterized in that the material of the hollow cube is high temperature resistant resin, magnetic resin or ceramic.

[0013] The terahertz broadband modulator based on 3D printing technology, wherein the built-in thin film layer and the active layer are both WTe2 thin film layers.

[0014] On the other hand, an embodiment of the present invention further provides a method for manufacturing a terahertz broadband modulator based on 3D printing technology, wherein the control device in the terahertz broadband modulator based on 3D printing technology described in the first aspect above can be manufactured by using the method for manufacturing a terahertz broadband modulator based on 3D printing technology, and the method comprises:

[0015] A structural layer is manufactured on a substrate by using a 3D printing technology of surface projection stereolithography, wherein the structural layer comprises a plurality of closely arranged hollow cubes; the upper end face and four side faces of the hollow cubes are provided with through holes connected to the internal cavity;

[0016] Depositing an active layer on the upper layer of the structural layer by magnetron sputtering, chemical vapor deposition, physical vapor deposition, vacuum evaporation or molecular beam epitaxy, and depositing a built-in thin film layer in the inner cavity of each of the hollow cubes;

[0017] Laying a protective layer on the upper layer of the active layer, wherein the width of the protective layer is smaller than the width of the active layer;

[0018] The first electrode layer and the second electrode layer are sputtered in the upper region of the active layer where the protective layer is not laid by magnetron sputtering to obtain a control device; the first electrode layer and the second electrode layer are respectively arranged on both sides of the protective layer.

[0019] An embodiment of the present invention provides a terahertz broadband modulator based on 3D printing technology and a manufacturing method thereof. The terahertz broadband modulator includes a field source and a control device. The control device includes a substrate, a structural layer arranged on the upper layer of the base, an active layer arranged on the upper layer of the structural layer, a protective layer arranged on the upper layer of the active layer, and a first electrode layer and a second electrode layer respectively arranged on both sides of the protective layer and in contact with the active layer; the structural layer is obtained by 3D printing technology of surface projection stereoscopic light curing; the structural layer is composed of a plurality of closely arranged hollow cubes; the upper end face and four side faces of the hollow cube are provided with through holes connected to the internal cavity; a built-in thin film layer is laid in the internal cavity of each hollow cube; the active layer is provided with a connecting hole corresponding to the through hole arranged on the upper end face of the hollow cube in the structural layer. The terahertz broadband modulator manufactured by the above-mentioned 3D printing technology based on surface projection stereolithography has a simple 3D printing manufacturing process and can efficiently produce hollow cubes of the subwavelength order. It has the advantages of high manufacturing precision, low cost and high speed. The subwavelength hollow cubes in the structural layer can be used to realize active control of terahertz based on active fields such as light field, electric field or magnetic field, thereby greatly improving the modulation effect of terahertz waves. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0021] Figure 1 An overall structural diagram of a control device in a terahertz broadband modulator based on 3D printing technology provided in an embodiment of the present invention;

[0022] Figure 2 A partial structural diagram of a control device in a terahertz broadband modulator based on 3D printing technology provided in an embodiment of the present invention;

[0023] Figure 3 A partial cross-sectional structural diagram of a control device in a terahertz broadband modulator based on 3D printing technology provided in an embodiment of the present invention;

[0024] Figure 4 A schematic diagram of an application scenario of a terahertz broadband modulator based on 3D printing technology provided by an embodiment of the present invention;

[0025] Figure 5 A flow chart of a method for manufacturing a terahertz broadband modulator based on 3D printing technology provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0028] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0029] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0030] In this example, see Figures 1 to 3As shown in the figure, an embodiment of the present invention provides a terahertz broadband modulator based on 3D printing technology, wherein the terahertz broadband modulator includes a field source 6 and a control device 1, wherein the control device 1 includes a substrate 11, a structural layer 12 disposed on the upper layer of the base 11, an active layer 13 disposed on the upper layer of the structural layer 12, a protective layer 14 disposed on the upper layer of the active layer 13, and a first electrode layer 15 and a second electrode layer 16 disposed on both sides of the protective layer 14 and in contact with the active layer 13; the first electrode layer 15 and the second electrode layer 16 are both in contact with the upper end surface of the active layer 13; the structural layer 12 is formed by surface projection stereolithography (Projection The structure layer 12 is made by 3D printing technology of MicroStereolithography (PμSL); the structure layer 12 is composed of a plurality of hollow cubes 120 arranged closely; the upper end face and four sides of the hollow cube 120 are provided with through holes 122 connected to the internal cavity 121; the internal cavity 121 of each hollow cube 120 is paved with a built-in thin film layer 123; the active layer 13 is provided with a connecting hole 131 corresponding to the through hole 122 provided on the upper end face of the hollow cube 120 in the structure layer 12, wherein the field source 6 generates an external field and acts on the surface of the control device 1, and the active control of the terahertz wave is realized by adjusting the intensity of the field source 6. The substrate 11 can be used to support other components arranged on the upper layer thereof to prevent the structure layer 12 from being deformed. The thickness of the substrate 11 can be slightly greater than the thickness of the structure layer 12. For example, in this embodiment, the thickness of the substrate 11 is set to 425μm. The substrate 11 is a silicon substrate or a silicon oxide substrate, and the substrate 11 can be made of Si material or SiO2.

[0031] The preparation of the structural layer 12 is to make a cubic circular hole metamaterial structure on the substrate 11 by 3D printing technology of surface projection stereolithography. The structural layer 12 is composed of a plurality of hollow cubes 120 arranged closely. For example, in this embodiment, a plurality of closely arranged hollow cubes 120 are combined in a horizontal and vertical array to obtain the structural layer 12, and the overall shape of the structural layer is a rectangle. The hollow cube 120 (cubic circular hole structure) included in the structural layer 12 is a sub-wavelength structural unit of the metamaterial, and the ratio between the side length L of the hollow cube 120 and the wavelength λ of the terahertz wave modulatable by the terahertz broadband modulator is 0.35 to 0.8. The wavelength λ of the terahertz wave is between 0.03 mm and 3 mm. If the wavelength λ of the modulated terahertz wave is 600 μm, the side length L of the hollow cube 120 can be set to 400 μm, and 25 hollow cubes 120 can be set in each row and 25 hollow cubes 120 in each column to form a 1 cm×1 cm structural layer 12. At this time, the overall shape of the structural layer 12 is a square.

[0032] The hollow cube 120 is provided with an internal cavity 121. Except for the bottom surface, a cylinder is dug out on each of the remaining surfaces of the hollow cube 120 to form a plurality of through holes 122 connected to the internal cavity 121. The material of the hollow cube 120 is a high temperature resistant resin, a magnetic resin or a ceramic. Specifically, the diameter D of the through hole 122 is 0.3 to 0.7 times the side length L of the hollow cube 120. The wall thickness W of the hollow cube 120 is 0.08 to 0.15 times the side length L thereof. The function of the through hole 122 is to limit the terahertz field and enhance the interaction between the field (terahertz field) and the structural layer 12. To improve the effect of the through hole 122, the diameter D of the through hole 122 can be set to 0.3 to 0.7 times the side length L of the hollow cube 120. Reasonable adjustment of the diameter D of the through hole 122 can enhance the modulation effect of the terahertz wave. For example, in this embodiment, the diameter D of the through hole 122 is set to 0.5 times the side length L of the hollow cube 120. For a hollow cube 120 with a side length L of 400 μm, the diameter D of the through hole can be set to 200 μm. The wall thickness W can also be set to 0.08 to 0.15 times the side length L. For example, in this embodiment, the wall thickness W is set to 0.125 times the side length L. For a hollow cube 120 with a side length L of 400 μm, the wall thickness W can be set to 50 μm.

[0033] The built-in thin film layer 123 and the active layer 13 provided in the hollow cube 120 are both WTe2 thin film layers. In the present embodiment, the active layer 13 can be deposited on the upper layer of the structural layer 12 by magnetron sputtering, chemical vapor deposition, physical vapor deposition, vacuum evaporation or molecular beam epitaxy. In the process of depositing the active layer 13, part of the active material enters the internal cavity 121 of the hollow cube 120 through the through hole 122 provided on the upper end surface of the hollow cube 120, thereby forming a built-in thin film layer 123 in the internal cavity 121. The built-in thin film layer 123 and the active layer 13 can be formed based on WTe2 deposition. For example, in the present embodiment, the thickness of the built-in thin film layer 123 and the active layer 13 is 1.5 μm. The WTe2 material belongs to the Weyl semimetal, and its band gap is close to 0. It has the advantages of high carrier mobility and high conductivity, and has the characteristics of anomalous Hall effect. The above-mentioned terahertz broadband modulator made based on the WTe2 material has the characteristics of low power consumption and high speed broadband. The built-in thin film layer 123 and the active layer 13 formed of WTe2 material can realize efficient active modulation of terahertz waves by being used in combination with the hollow cube 120 with a subwavelength structure.

[0034] A protective layer 14 is also provided on the upper layer of the active layer 13. Specifically, the protective layer 14 is a silicon oxide layer or a hexagonal boron nitride layer. A first electrode layer 15 and a second electrode layer 16 are provided on both sides of the protective layer 14. Specifically, the first electrode layer 15 and the second electrode layer 16 can be made of metal materials such as gold, copper or aluminum. The thickness of the first electrode layer 15 and the second electrode layer 16 are both 200-300nm and the width is 0.8-1.25mm, that is, the width of the first electrode layer 15 and the second electrode layer 16 are both about 1mm. The thickness of the protective layer 14 is 200-300nm.

[0035] In specific applications, the active control of terahertz waves based on the control device 1 can be achieved by adding an external light source, an external power source or an external magnetic field. For example, the external light source can be a semiconductor light source with a power density adjustment range of 0 to 1 W / cm 2 ; The external power supply adjustment range is 0~30V; The external magnetic field can be achieved using a Helmholtz coil.

[0036] The terahertz broadband modulator manufactured in this embodiment has the following advantages: (1) The cubic circular hole structure is manufactured using the 3D printing technology of surface projection stereolithography. The 3D printing manufacturing process is simple and has the advantages of high precision, low cost, and fast manufacturing speed. It can efficiently manufacture sub-wavelength-level microstructures; (2) WTe2 material belongs to Weyl semimetal, and its band gap is close to 0, which can be modulated broadband. It has the advantages of high carrier mobility and high conductivity, and is very suitable as a material for low-power, high-speed modulators; (3) WTe2 thin film can be prepared by various methods such as magnetron sputtering, which is relatively simple to prepare and has the characteristics of high versatility and popularity; (4) Combining the cubic circular hole metamaterial structure with the WTe2 thin film is conducive to enhancing the interaction between the terahertz wave and the modulator, and effectively improving the modulation depth of the terahertz modulator. ; (5) The device can control a variety of active fields, such as light field, electric field, and magnetic field. By changing the intensity of the external field, the active control of the terahertz wave can be achieved.

[0037] Figure 4 A schematic diagram of an application scenario of a terahertz broadband modulator based on 3D printing technology provided for an embodiment of the invention, that is, a schematic diagram of a modulation process for actively modulating terahertz waves using the above-mentioned terahertz broadband modulator. Figure 4 The experimental device included in the application scenario is a reflective terahertz time-domain spectrum system, such as Figure 4As shown, it mainly includes a femtosecond laser 2, a terahertz generating end 3, a control device 1, a terahertz detection end 4, a terahertz signal processing device 5 and a field source 6. The terahertz signal processing device 5 is used to detect the reflection spectrum of the terahertz wave after being regulated by the metamaterial tuning device (control device 1) and the external field; the femtosecond laser 2 is a femtosecond laser with a wavelength of 780nm; the terahertz generating end 3 is used to generate terahertz waves, and the terahertz detection end 4 is used to detect the generated terahertz waves.

[0038] After the control device 1 is manufactured, a modulation experiment is performed on the control device 1. The prepared control device 1 and the field source 6 are compared with Figure 4 Placement. First, the laser emitted by the 780nm femtosecond laser 2 passes through the beam splitter, and one of the beams passes through the delay device, and then generates a terahertz wave through the terahertz generating end 3, and the terahertz wave is collimated and focused by two off-axis parabolic mirrors, and then obliquely incident on the control device 1, and the modulated terahertz wave is reflected and then incident on the terahertz detection end 4 through two off-axis parabolic mirrors; the other beam emitted by the beam splitter is coherent with the terahertz wave at the terahertz detection end 4, and then the time domain spectrum of the terahertz wave is obtained through detection, and the field source 6 obliquely incidents the external light source on the surface of the control device 1, and the intensity of the field source 6 is adjusted to realize the active control of the terahertz wave; finally, the result is processed on the terahertz signal processing device 5. In the implementation process here, a pump light source is used as the field source 6. In the actual process of modulating the terahertz wave, an active field source such as an electric field or a magnetic field can also be used.

[0039] See also Figure 5 , Figure 5 The present invention also provides a method for manufacturing a terahertz broadband modulator based on 3D printing technology, which can be used to manufacture the control device in the above-mentioned terahertz broadband modulator based on 3D printing technology, such as Figure 5 As shown, the method includes steps S110 to S140.

[0040] S110. A structural layer is manufactured on a substrate by using a 3D printing technology of surface projection stereolithography, wherein the structural layer comprises a plurality of closely arranged hollow cubes; the upper end face and four side faces of the hollow cubes are provided with through holes connected to the internal cavity.

[0041] S120, depositing an active layer on the upper layer of the structural layer by magnetron sputtering, chemical vapor deposition, physical vapor deposition, vacuum evaporation or molecular beam epitaxy, and depositing a built-in thin film layer in the inner cavity of each hollow cube.

[0042] S130: Laying a protective layer on the upper layer of the active layer, wherein the width of the protective layer is smaller than the width of the active layer.

[0043] S140, forming a first electrode layer and a second electrode layer by sputtering in an area of ​​the upper layer of the active layer where the protective layer is not laid by a magnetron sputtering method to obtain a control device; the first electrode layer and the second electrode layer are respectively arranged on both sides of the protective layer.

[0044] The present invention combines the WTe2 film with the metamaterial structure to manufacture a terahertz high-speed multi-field active control broadband modulator based on 3D printing. In this embodiment, the structure layer 12 of the cubic circular hole resin is made on the Si wafer by the surface projection stereoscopic light curing technology, and the WTe2 film can be evaporated on the resin by magnetron sputtering. At the same time, the metal electrodes can be evaporated on both ends of the film by magnetron sputtering to complete the manufacture of the terahertz modulator.

[0045] In an embodiment of the present invention, a terahertz broadband modulator based on 3D printing technology and a manufacturing method thereof are provided. The broadband modulator includes a field source and a control device. The control device includes a substrate, a structural layer arranged on the upper layer of the base, an active layer arranged on the upper layer of the structural layer, a protective layer arranged on the upper layer of the active layer, and a first electrode layer and a second electrode layer respectively arranged on both sides of the protective layer and in contact with the active layer; the structural layer is obtained by 3D printing technology of surface projection stereoscopic photocuring; the structural layer is composed of a plurality of closely arranged hollow cubes; the upper end face and four side faces of the hollow cube are provided with through holes connected to the internal cavity; a built-in thin film layer is laid in the internal cavity of each hollow cube; the active layer is provided with a connecting hole corresponding to the through hole provided on the upper end face of the hollow cube in the structural layer. The broadband modulator manufactured by the above-mentioned 3D printing technology based on surface projection stereolithography has a simple 3D printing manufacturing process and can efficiently produce hollow cubes of the subwavelength order. It has the advantages of high manufacturing precision, low cost and high speed. The subwavelength hollow cubes in the structural layer can realize active control of terahertz based on active fields such as light field, electric field or magnetic field, which greatly improves the modulation effect of terahertz waves.

[0046] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A terahertz broadband modulator based on 3D printing technology, characterized in that: The terahertz broadband modulator includes a field source and a control device, wherein the control device includes a substrate, a structural layer arranged on the substrate, an active layer arranged on the structural layer, a protective layer arranged on the active layer, and a first electrode layer and a second electrode layer respectively arranged on both sides of the protective layer and in contact with the active layer; the first electrode layer and the second electrode layer are both in contact with the upper end surface of the active layer; The structural layer is made by 3D printing technology of surface projection stereolithography; the structural layer is composed of a plurality of hollow cubes arranged closely; the upper end face and four side faces of the hollow cube are provided with through holes connected to the internal cavity; the internal cavity of each hollow cube is paved with a built-in film layer; the built-in film layer and the active layer are both WTe2 film layers; The active layer is provided with a connecting hole corresponding to the through hole provided on the upper end surface of the hollow cube in the structural layer; The field source is an electric, magnetic or laser field, which generates an external field and acts on the surface of the control device. The active control of the terahertz wave is achieved by adjusting the intensity of the field source.

2. The terahertz broadband modulator based on 3D printing technology according to claim 1, characterized in that: The diameter of the through hole is 0.3 to 0.7 times the side length of the hollow cube.

3. The terahertz broadband modulator based on 3D printing technology according to claim 1, characterized in that: The wall thickness of the hollow cube is 0.08 to 0.15 times of its side length.

4. The terahertz broadband modulator based on 3D printing technology according to any one of claims 1 to 3, characterized in that: The overall shape of the structural layer is a square.

5. The terahertz broadband modulator based on 3D printing technology according to claim 4, characterized in that: The ratio between the side length of the hollow cube and the wavelength of the terahertz wave modulatable by the terahertz broadband modulator is 0.35 to 0.

8.

6. The terahertz broadband modulator based on 3D printing technology according to any one of claims 1 to 3, characterized in that: The substrate is a silicon substrate or a silicon oxide substrate.

7. The terahertz broadband modulator based on 3D printing technology according to any one of claims 1 to 3, characterized in that: The protective layer is a silicon oxide layer or a hexagonal boron nitride layer.

8. The terahertz broadband modulator based on 3D printing technology according to any one of claims 1 to 3, characterized in that: The material of the hollow cube is high temperature resistant resin, magnetic resin or ceramic.

9. A method for manufacturing a terahertz broadband modulator based on 3D printing technology, characterized in that: The control device in the terahertz broadband modulator based on 3D printing technology as claimed in any one of claims 1 to 8 is manufactured by a manufacturing method of a terahertz broadband modulator based on 3D printing technology, the method comprising: A structural layer is manufactured on a substrate by using a 3D printing technology of surface projection stereolithography, wherein the structural layer comprises a plurality of closely arranged hollow cubes; the upper end face and four side faces of the hollow cubes are provided with through holes connected to the internal cavity; Depositing an active layer on the upper layer of the structural layer by magnetron sputtering, chemical vapor deposition, physical vapor deposition, vacuum evaporation or molecular beam epitaxy, and depositing a built-in thin film layer in the inner cavity of each of the hollow cubes; Laying a protective layer on the upper layer of the active layer, wherein the width of the protective layer is smaller than the width of the active layer; The first electrode layer and the second electrode layer are sputtered in the upper region of the active layer where the protective layer is not laid by magnetron sputtering to obtain a control device; the first electrode layer and the second electrode layer are respectively arranged on both sides of the protective layer.

Images