Patent ID: 12222381

DETAIL DESCRIPTION OF EMBODIMENTS

In order to enable those of ordinary skill in the art to better understand the technical solutions of the present disclosure, the present disclosure is further described in detail below with reference to the accompanying drawings and specific embodiments.

Unless otherwise defined, technical terms or scientific terms used herein should have general meanings that are understood by those of ordinary skill in the technical field to which the present disclosure belongs. The words “first”, “second” and the like used herein do not denote any order, quantity or importance, but are just used to distinguish between different elements. Similarly, the words “an”, “a”, “the” and the like do not denote a limitation to quantity, and indicate the existence of “at least one” instead. The words “include”, “comprise” and the like indicate that an element or object before the words covers the elements or objects or the equivalents thereof listed after the words, rather than excluding other elements or objects. The words “connect”, “couple” and the like are not limited to physical or mechanical connection, but may also indicate electrical connection, whether direct or indirect. The words “on”, “under”, “left”, “right” and the like are only used to indicate relative positional relationships. When an absolute position of an object described is changed, the relative positional relationships may also be changed accordingly.

FIG.1is a schematic structural diagram of an exemplary thin film sensor; andFIG.2is a schematic cross-sectional diagram of a structure of the thin film sensor shown inFIG.1taken along A-A′ direction. As shown inFIG.1andFIG.2, the thin film sensor includes: a base substrate100having a first surface and a second surface, i.e., an upper surface and a lower surface, which are arranged opposite to each other; and a first conductive layer101and a second conductive layer102, which are located on the first surface and the second surface of the base substrate100respectively. Taking a case where the thin film sensor is a transparent antenna as an example, the first conductive layer101may be a radiation layer, and the second conductive layer102may be a ground layer. The radiation layer may be used as a receiving unit of an antenna structure and may also be used as a transmitting unit of the antenna structure.

In order to ensure that the first conductive layer101and the second conductive layer102have good light transmittance, the first conductive layer101and the second conductive layer102need to be patterned, for example, the first conductive layer101may be formed by grid lines made of a metal material, and the second conductive layer102may also be formed by grid lines made of a metal material. It should be understood that the first conductive layer101and the second conductive layer102may also be formed into structures having other patterns such as a rhombic block electrode and a triangular block electrode, which are not listed one by one here. As can be seen fromFIG.1, the first conductive layer101and the second conductive layer102, i.e., the grid lines, are not arranged all over the two surfaces of the base substrate100. Any one of the grid lines is formed by electrically connected metal grids. Due to a material and a manufacturing process of the metal grids, the metal grid has a relatively large line width, which significantly affects the light transmittance of the thin film sensor, and further affects user experience.

It should be noted that the thin film sensor is not limited to be applied to an antenna structure, and can also be used in a touch panel as a touch electrode. The thin film sensor can also be used in various metal wires, which are not listed one by one here.

In order to solve the above technical problem, the embodiments of the present disclosure provide the following technical solutions. Before the thin film sensor provided by the embodiments of the present disclosure is described, it should be noted that a material of the thin film sensor provided by the embodiments of the present disclosure is a conductive material with relatively low transmittance, and the material includes, but is not limited to, a metal, a metal oxide, Graphene and the like, that is, a material of a conductive wire includes, but is not limited to, a metal, a metal oxide, Graphene and the like. The following description is given by taking a case where the conductive wire is a metal wire as an example, but it should be understood that the embodiments of the present disclosure are not limited thereto.

In a first aspect,FIG.3is a perspective view of a thin film sensor according to an embodiment of the present disclosure;FIG.4is a top view of a metal wire200in a thin film sensor according to an embodiment of the present disclosure; andFIG.5is a schematic cross-sectional diagram of a structure of the thin film sensor shown inFIG.3taken along B-B′ direction. The embodiment of the present disclosure provide a thin film sensor, which may include a base substrate100, a plurality of metal wires200disposed on the base substrate100and intersecting one another, and a functional structure. Part of the plurality of metal wires200extend along a first direction X and are arranged side by side along a second direction Y, and the remaining metal wires200extend along the second direction Y and are arranged side by side along the first direction X. The first direction X intersects the second direction Y, and hollow-out areas defined by the first direction X and the second direction Y correspond to hollow-out parts defined by intersection of the metal wires200, and a shape of the hollow-out area includes, but is not limited to, a rhombus. In the embodiment of the present disclosure, the functional structure is configured to allow at least part of light, which is transmitted along a preset direction and enters the functional structure from regions where the conductive wires are located, to exit from the hollow-out parts; and the preset direction is a direction from the base substrate100towards the metal wires200.

Since the thin film sensor provided by the embodiment of the present disclosure is provided therein with the functional structure, and the functional structure can allow at least part of the light, which is transmitted along the preset direction and enters the functional structure from the regions where the conductive wires are located, to exit from the hollow-out parts, that is, at least part of light, which is irradiated to the regions where the conductive wires are located, can exit by bypassing the metal wires200under the action of the functional structure, the light transmittance can be greatly increased.

In order to clarify a structure of the thin film sensor in the embodiments of the present disclosure, the thin film sensor in the embodiments of the present disclosure is described below in conjunction with specific exemplary implementations.

In an exemplary implementation, as shown inFIG.5, the functional structure in the thin film sensor includes a first medium layer300disposed between a layer where the metal wires200are located and a layer where the base substrate100is located. The thin film sensor further includes a planarization layer500covering a side of a layer where the metal wires200are located away from the base substrate100. The first medium layer300includes a plurality of first main portions301arranged in an intersecting way, and orthographic projections of the first main portions301on the base substrate100overlap those of the metal wires200on the base substrate100one to one. For example, the first main portions301are disposed in one-to-one correspondence with the metal wires200, and the orthographic projections of the first main portions301on the base substrate100totally overlap those of the metal wires200on the base substrate100, respectively. That is, a pattern of the first medium layer300is the same as that defined by the plurality of metal wires200. In this case, the planarization layer500not only covers the metal wires200, but also covers sidewalls of the first main portions301with a material of the planarization layer500which falls in the hollow-out parts. In such thin film sensor structure, a refractive index of the planarization layer500is greater than that of the first medium layer300, that is, the refractive index of the planarization layer500is greater than that of the first main portions301.

With reference toFIG.5, in the thin film sensor according to the embodiment of the present disclosure, the metal wires200are disposed in one-to-one correspondence with the main portions of the first medium layer300, the first main portions301are located below the metal wires200(on a side of the metal wires close to the base substrate100), and the first main portions and the metal wires are all located in the regions where the conductive wires are located; the metal wires200are covered with the planarization layer400above, and the planarization layer400is located in the regions where the conductive wires are located and the hollow-out parts to fill up the hollow-out parts of the thin film sensor, so as to flatten a surface of the thin film sensor. In this case, the sidewalls of the first main portions301are in contact with the planarization layer400. Meanwhile, the refractive index of the first main portions301is less than that of the planarization layer400in the embodiment of the present disclosure. Thus, in a case where part of light emitted along the preset direction is irradiated to the regions where the conductive wires of the thin film sensor are located, since the refractive index of the first main portions301is less than that of the planarization layer400and an effect similar to diffraction occurs when light passes through mediums with non-uniform refractive indices, when the light enters the first main portions301, part of the light is transmitted into the planarization layer400with the relatively large refractive index, that is, part of the light bypasses the metal wires200, enters the hollow-out parts and exits from the hollow-out parts, so that the light is prevented from being irradiated to the metal wires200to be directly absorbed or reflected, thereby greatly increasing the light transmittance.

In some exemplary implementations, both of a material of the first medium layer300and that of the planarization layer400may be an optically transparent organic material or an optically transparent inorganic material. The optically transparent organic material includes, but is not limited to, COP, polyethylene terephthalate (PET), OCA adhesive, optical plastic CR-39, cured PMMA, SUB, AZ5214 and the like; and the optically transparent inorganic material includes, but is not limited to, SiO, Al2O3, ZnO, SiN and the like. It should be understood that any case where a refractive index of the optically transparent material of the first medium layer300is less than that of the optically transparent material of the planarization layer400should fall within the scope of the embodiments of the present disclosure.

With reference toFIG.5, the first main portion301has a first section perpendicular to an extending direction thereof. The first section is rectangular. In order to guarantee a sufficient diffraction propagation distance, the first main portion301having the rectangular first section is generally required to have a relatively large thickness. In some exemplary implementations, a height of the first section is at least 1.5 times of a width of the first section, and 2 times or more than 2 times is optional. That is, the thickness of the first main portion301is at least 1.5 times of a line width thereof. Within a reasonable range, the greater the thickness of the first main portion301, the higher the transmittance of the thin film sensor. For example, the metal wire200is made of a silver material with a line width of 3 μm and a thickness of 60 nm; the line width of the first main portion301is the same as that of the metal wire200, i.e., 3 μm, and the thickness of the first main portion301is set to 6 μm or 11.5 μm; the refractive index of the first main portion301is set to 1.53 in a visible light band (in this case, the first main portion301is made of COP), and the refractive index of the planarization layer400is set to 1.6 in the visible light band (in this case, the planarization layer400is made of the OCA adhesive). It can be seen inFIG.6that the maximum light transmittance within the width of 3 μm is only 17% (S101inFIG.6) because light is blocked by the metal wires200with the width of 3 μm. The maximum light transmittance can be increased to approximately 28% (S102inFIG.6) through compensation by the first medium layer300. The magnitude of the transmittance is also closely related to a thickness of the first medium layer300(the first main portions301). As shown inFIG.6, compared with the first medium layer300with the thickness of 6 μm, the first medium layer300with the thickness of 11.5 μm is more likely to cause the greater transmittance (S103).

It should be noted that the above description is given by taking a case where the first section of the first main portion301is rectangular as an example. In practical products, a shape of the first section of the first main portion301is not limited to the rectangle, and may be any shape such as an inverted triangle, an inverted trapezoid, or a semi-ellipse, and those shapes are not listed one by one here.

In view of the above thin film sensor structure, the embodiments of the present disclosure further provides a manufacturing method of a thin film sensor, which includes the following steps S11to S14.

At step S11, a base substrate100is provided.

The base substrate100may be a flexible thin film, and a material of the flexible thin film may be at least one of COP, polyimide (PI) or polyethylene terephthalate (PET).

At step S12, a pattern including a first medium layer300is formed on the base substrate100.

Taking a case where the first medium layer300is made of an organic curing adhesive which is capable of being cured at a low temperature, in the step S12, a layer of the organic curing adhesive and a layer of a photoresist may be coated on the base substrate100first, then processes of exposure, development and etching are performed to remove the organic curing adhesive corresponding to hollow-out parts, and finally the remaining organic curing adhesive is cured at a low temperature, thereby forming the first medium layer300having first main portions301arranged in an intersecting way.

At step S13, a pattern of metal wires200is formed by a patterning process on the base substrate100on which the first medium layer300is formed.

Specifically, the step S13may include forming a metal thin film on a side of the first medium layer300away from the base substrate100by, but not limited to, a sputtering process, coating a photoresist, and then removing metal materials corresponding to the hollow-out parts by processes of exposure, development and etching, thereby forming a plurality of metal wires200arranged in an intersecting way.

At step S14, a planarization layer400is formed on the base substrate100on which the metal wires200are formed.

In the step S14, the planarization layer400may be deposited through Plasma Enhanced Chemical Vapor Deposition, Low Pressure Chemical Vapor Deposition, Atmospheric Pressure Chemical Vapor Deposition or Electron Cyclotron Resonance Chemical Vapor Deposition.

Thus, manufacturing of the thin film sensor shown inFIG.5is completed.

In another exemplary implementation,FIG.7toFIG.10are schematic cross-sectional diagrams of other structures of the thin film sensor according to an embodiment of the present disclosure. As shown inFIG.7toFIG.10, the functional structure of the thin film sensor includes not only the first medium layer300but also a second medium layer500, and a refractive index of the second medium layer500is greater than that of the first medium layer300. The second medium layer500is provided with a plurality of first grooves arranged in an intersecting way; and the first main portions of the first medium layer300are disposed in the first grooves, and the first main portions301are disposed in one-to-one correspondence with the first grooves, for example, the first main portions301are in one-to-one correspondence with the first grooves. The metal wires200are located on a side of the first main portions301away from the base substrate100.

With reference toFIG.7, since the first main portions301are disposed in the first grooves, the sidewalls of the first main portions301are wrapped by the second medium layer500. In a case where part of the light emitted along the preset direction is irradiated to the regions where the conductive wires of the thin film sensor are located, since the refractive index of the first medium layer300is less than that of the second medium layer500and an effect similar to diffraction occurs when light passes through the mediums with non-uniform refractive indices, when the light enters the first main portions301, part of the light is transmitted to the second medium layer500with the relatively large refractive index, that is, part of the light bypasses the metal wires200, enters the hollow-out parts and exits from the hollow-out parts, so that the light is prevented from being irradiated to the metal wires200to be directly absorbed or reflected, thereby greatly increasing the light transmittance.

In some exemplary implementations, a material of the first medium layer300may be same as that of the first medium layer300in the thin film transistor shown inFIG.5. A material of the second medium layer500may be the same in type as that of the first medium layer300, that is, the material of the second medium layer500may be the optically transparent organic material or the optically transparent inorganic material. The optically transparent organic material includes, but is not limited to, COP, PET, OCA adhesive, optical plastic CR-39, cured PMMA, SUB, AZ5214 and the like; and the optically transparent inorganic material includes, but is not limited to, SiO, Al2O3, ZnO, SiN and the like. It should be understood that any case where a refractive index of the optically transparent material of the first medium layer300is less than that of the optically transparent material of the second medium layer500should fall within the scope of the embodiments of the present disclosure.

In some exemplary implementations, the planarization layer400is further disposed on the side of the metal wires200away from the base substrate100. A material of the planarization layer400may be the same as that of the second medium layer500, or may be an optically transparent material having a refractive index, a difference between which and the refractive index of the second medium layer500is not greater than 0.2.

In some exemplary implementations, the first grooves formed in the second medium layer500are usually not in a shape of a rectangle for processing reasons. Correspondingly, the first sections of the first main portions301formed in the first medium layer300are not rectangular. That is, the first section includes a top edge disposed away from the base substrate100and at least one side edge connected to the top edge, with an included angle between a tangent of any point on the side edge and the top edge away from the base substrate100being not greater than 90°. Specifically, when the first grooves are inverted triangular grooves, the first sections of the first main portions301are inverted triangular accordingly, as shown inFIG.7. When the first grooves are inverted trapezoidal grooves, the first sections of the first main portions301are inverted trapezoidal accordingly, as shown inFIG.8. When the first grooves are semi-elliptical grooves, the first sections of the first main portions301are semi-elliptical accordingly, as shown inFIG.9. It can be seen that the first main portions301and the first grooves are matched with each other. As shown inFIG.10, when the first main portions301are formed, surfaces of the first main portions301away from the base substrate100are not necessarily flat for processing reasons. Therefore, a flat part302is formed by a leveling process on the surfaces of the first main portions301away from the base substrate100, that is, the first medium layer300includes not only the first main portions301but also the flat part302connected with the first main portions301.

An effect of increasing the transmittance of the thin film sensor by providing the first medium layer300and the second medium layer500is described by taking the thin film sensor which is provided with the first main portions301having the inverted triangular first sections or the inverted trapezoidal first sections as an example.

When the line width of the metal wire200is 3 μm, the line width of the first main portion301having the inverted triangular first section is also 3 μm, and a height of the inverted triangular first section is 8 μm, that is, the thickness of the first main portion301is 8 μm. When the line width of the metal wire200is 3 μm, a line width of a surface of the first main portion301having the inverted trapezoidal first section, which is in contact with the metal wire200, is also 3 μm, a line width of a surface of the first main portion301having the inverted trapezoidal first section, which is away from the metal wire200is 1 μm, and a height of the inverted trapezoidal first section is 5 μm, that is, the thickness of the first main portion301is 5 μm. The refractive index of the first main portion301(the first medium layer300) having the inverted triangular first section or the inverted trapezoidal first section is set to 1.48, and the refractive index of the second medium layer500is set to 1.6, that is, a difference between the refractive indices of the first medium layer300and the second medium layer500is 0.12. As shown inFIG.11, the light transmittance reaches 90% or more over the entire visible light band through the compensation by the first main portion301having the inverted triangular first section (S202inFIG.11). The light transmittance is also increased from 17% (S201inFIG.11) to 55% or more (S203inFIG.11) through the compensation by the first main portion301having the inverted trapezoidal first section.

For the thin film sensor provided with the functional structure including the first medium layer300and the second medium layer500, manufacturing methods of a thin film sensor are also provided below. One of the methods can achieve formation of the rectangular first grooves, and the other method can achieve formation of the non-rectangular first grooves. The two methods are respectively described below.

The manufacturing method of the thin film sensor provided with the rectangular first grooves may include the following steps S21to S24.

At step S21, the base substrate100is provided.

The base substrate100may be a flexible thin film, and a material of the flexible thin film may be at least one of COP, polyimide (PI) or polyethylene terephthalate (PET).

At step S22, a pattern including the second medium layer500is formed by a patterning process on the base substrate100.

Specifically, the step S22may include forming a second material layer on the base substrate100, coating a photoresist on the second material layer, and then exposing, developing, and etching to form the second medium layer500having the rectangular first grooves.

At step S23, a pattern including the first medium layer300and the metal wires200are formed on a side of the second medium layer500away from the base substrate100.

Specifically, the step S23may include sequentially coating a first material layer and a metal material layer on the side of the second medium layer500away from the base substrate100, with thicknesses of the first material layer and the metal material layer both much less than that of the second material layer, and the first material layer and the metal material layer falling in the first grooves separated from the first material layer and the metal material layer covering the first grooves; and removing the metal material layer outside the first grooves with a strong adhesive tape, thereby forming the metal wires200and the first main portions301located below the metal wires200.

At step S24, the planarization layer400is formed on the base substrate100on which the metal wires200are formed.

In the step S24, the planarization layer400may be deposited through Plasma Enhanced Chemical Vapor Deposition, Low Pressure Chemical Vapor Deposition, Atmospheric Pressure Chemical Vapor Deposition or Electron Cyclotron Resonance Chemical Vapor Deposition.

Thus, manufacturing of the thin film sensor provided with the rectangular first grooves is completed.

The manufacturing method of the thin film sensor provided with the non-rectangular first grooves may include the following steps S31to S34.FIG.10illustrates an example in which the first grooves are inverted trapezoidal and the first medium layer300includes the first main portions301and the flat part302.

At step S31, the base substrate100is provided.

The base substrate100may be a flexible thin film, and a material of the flexible thin film may be at least one of COP, polyimide (PI) or polyethylene terephthalate (PET).

At step S32, a pattern including the second medium layer500is formed by a patterning process on the base substrate100.

Specifically, the step S32may include forming a second material layer on the base substrate100, coating a photoresist on the second material layer, and then exposing, developing, and etching to form the second medium layer500having the inverted trapezoidal first grooves.

At step S33, the first medium layer300is formed on the side of the second medium layer500away from the base substrate100.

Specifically, the step S33may include coating a first material layer on the side of the second medium layer500away from the base substrate100, with the first material layer filling the first grooves for forming the first main portions301of the first medium layer300, and the first material layer covering the second medium layer500for forming the flat part302of the first medium layer300, thereby forming the first medium layer300.

At step S34, a pattern including the metal wires200is formed by a patterning process on the base substrate100on which the first medium layer300is formed.

Specifically, the step S34may include forming a metal thin film on the side of the first medium layer300away from the base substrate100by, but not limited to, a sputtering process, coating a photoresist, and then removing metal materials corresponding to the hollow-out parts by processes of exposure, development and etching, thereby forming a plurality of metal wires200arranged in an intersecting way.

Thus, manufacturing of the thin film sensor is completed.

It should be noted that the manufacturing method may further include a step of forming the planarization layer400after the step S34, and the formation step is the same as the above step of forming the planarization layer400, and thus is not repeated here.

In another exemplary implementation,FIG.12is a schematic cross-sectional diagram of a structure of the thin film sensor according to an embodiment of the present disclosure. The structure of the thin film sensor shown inFIG.12is substantially the same as that of the thin film sensor shown inFIG.5, except that micro-nano scattering particles304or micro-nano scattering pores are doped in the first main portions of the first medium layer300, so as to increase the light transmittance better. The micro-nano scattering particles include, but are not limited to, metal particles or dielectric particles.

With reference toFIG.12, the line width of the metal wire200in the thin film sensor is 3 μm, the line width of the first main portion301is also 3 μm, and the thickness of the first main portion301is 11 μm. The first main portion301is uniformly doped with micro-nano metal scattering particles with diameters of 10 nm to 100 nm, or dielectric nanoparticles with a refractive index greater than that of the first main portion301, or air pores with a refractive index less than that of the first main portion301. As shown inFIG.13, it can be seen that the light transmittance can be increased from 0.17 (S301inFIG.13) to 0.27 (S302inFIG.13).

In some exemplary implementations, the dielectric nanoparticles having the refractive index greater than that of the first main portion301may include titanium dioxide particles, silicon spherical particles and the like. It is also possible to design shapes of the dielectric particles in such a way that resonance of an electric dipole and resonance of a magnetic dipole can be simultaneously excited to generate zero backscattering, so as to further improve optical forward-scattering, thereby increasing the light transmittance. It should be noted that a density of the micro-nano metal particles is required not to be too large when the first main portion301is doped with the micro-nano metal particles. This is because metal has a relatively large ohmic loss and can produce a reflection effect, and too many micro-nano metal particles will lead to reflection and absorption of energy instead of forward transmission. Preferably, the diameters of the micro-nano metal particles are from 10 nm to 100 nm, and a concentration of the micro-nano metal particles is about 1 to 2 particles per cubic micrometer.

In addition, the above description is given by taking a case where the first sections of the first main portions301are rectangular as an example. Actually, the micro-nano scattering particles or the micro-nano scattering pores can be also doped in the first main portions301shown inFIG.7toFIG.10. In all of those cases, the light transmittance can be effectively increased, and those cases are not listed one by one here.

In another exemplary implementation,FIG.14is a schematic cross-sectional diagram of a structure of the thin film sensor according to an embodiment of the present disclosure. As shown inFIG.14, the functional structure in the thin film sensor includes a third medium layer600disposed between the layer where the metal wires200are located and the layer where the base substrate100is located. The thin film sensor further includes a fourth medium layer700disposed between the third medium layer600and the metal wires200. The third medium layer600includes a plurality of second main portions arranged in an intersecting way; and an orthographic projection of the second main portions on the base substrate100overlap those of the metal wires200on the base substrate100respectively. For example, the second main portions are disposed in one-to-one correspondence with the metal wires200, and the orthographic projections of the second main portions on the base substrate100overlap those of the corresponding metal wires on the base substrate100, respectively. The third medium layer600is capable of reflecting light, and also has certain light transmittance. Since the third medium layer600and the metal wires200are disposed opposite to each other and separated from each other by a certain distance, the third medium layer600(the second main portions) and the metal wires200form optical microcavities. In this case, light entering the optical microcavity is changed in transmission direction under the reflection action of the second main portions and the metal wires200, and finally bypasses the metal wires200and exists from the hollow-out parts.

In some exemplary implementations, an overlapping area of the second main portion with the metal wire200is not greater than 10% of an area of the metal wire200, and better light transmission may be achieved by reasonably setting the overlapping area of the second main portion with the metal wire200.

In some exemplary implementations, the third medium layer600includes, but is not limited to, any one of a metal film, a semi-reflective and semi-transmissive film, and a distributed Bragg reflector (DBR). For example, the third medium layer600may be a silver film with a thickness from 10 nm to 40 nm.

In some exemplary implementations, a material of the metal wires200includes, but is not limited to, at least one of aluminum, copper, silver and gold. When reflectivity of the metal wires200is low, reflective sheets800may be formed on a side of the metal wires200close to the second main portions, for example, a layer of silver film or a layer of aluminum film is formed as the reflective sheets800to enhance the reflectivity of the metal wires200, so that light can be reflected between the metal wires200and the second main portions to be changed in transmission direction, thereby further increasing the light transmittance of the thin film sensor.

In some exemplary implementations, the thin film sensor further includes the planarization layer400disposed on the side of the plurality of metal wires200away from the base substrate100; and a difference between refractive indices of the planarization layer400and the fourth medium layer700is not greater than 0.05. Preferably, the planarization layer400is made of a same material as the fourth medium layer700, so as to ensure that there is no difference between the refractive indices of the fourth medium layer700and the planarization layer400, so that the problem of reduction of optical diffraction efficiency caused by the interface reflection occurring when light leaks from the optical microcavities to the planarization layer400is minimized.

For the thin film sensor shown inFIG.14, the optical microcavfunctions as an anti-reflection layer for light waves in a particular wavelength band. Assuming that energy of incident light is 1, energy obtained after the incident light is transmitted through the metal wires200by diffraction is equal to 1-reflectivity-absorpitivity. When the reflectivity is greatly reduced by the optical microcavity, a proportion of the energy obtained after the incident light is transmitted through the metal wires200by diffraction can be increased correspondingly. After the optical microcavity is formed, more energy of the incident light is concentrated in the optical microcavity at a resonant wavelength point of visible light, and the incident light passes through the metal wires200above through diffraction from left and right openings of the optical microcavity. More electromagnetic energy is directly reflected at a non-resonance point, which reduces probability of diffractive transmission.

It should be noted that the larger the thickness of the optical microcavity, the more the wavelength bands where anti-reflection occur; meanwhile, a spectrum of each resonant wavelength band of the optical microcavity is generally narrow, so that a resonant wavelength is very sensitive to the thickness of the optical microcavity, and a change of the thickness by dozens of nanometers can cause a significant shift of a resonant peak. As shown inFIG.16, when the thickness of the optical microcavity is changed from 1.6 μm to 1.55 μm, and a wavelength of each resonant peak is significantly shifted (S402is shifted to S403inFIG.16). InFIG.16, the transmittance of the metal wires200can be increased from 0.17 (S401inFIG.16) to 0.32 (S402and S403inFIG.16) at the resonance wavelength due to an enhanced diffraction effect, that is, the light transmittance is almost doubled. The thickness of the optical microcavity is determined by a thickness of the fourth medium layer700, so that it is especially important to reasonably set the thickness of the fourth medium layer700.

In addition, the method of compensating for the transmittance of the metal wires200with the optical resonance cavity is very sensitive to an incident angle. As can be seen inFIG.13, when the incident angle is just changed from 0° to 5°, the wavelength of the resonant peak is significantly shifted (S501is shifted to S502inFIG.17). As the incident angle continues to increase, the shift of the wavelength of the resonant peak becomes more significant.

It should be understood that the above embodiments are merely exemplary embodiments adopted to illustrate the principle of the present disclosure, and the present disclosure is not limited thereto. Various modifications and improvements can be made by those of ordinary sill in the art without departing from the spirit and essence of the present disclosure, and those modifications and improvements should also fall within the scope of the present disclosure.