CN116299817A - An Optical Frequency Selective Surface for Visible Light Transmission and Near Infrared Shielding - Google Patents

Abstract

The invention belongs to the technical field of optical frequency selective surfaces, and provides an optical frequency selective surface capable of shielding visible light through near infrared rays, which comprises a substrate, a metal-dielectric film structure and an antireflection layer; the metal-dielectric film structure sequentially comprises a metal layer-dielectric layer-metal layer, a dielectric layer-metal layer-dielectric layer or a dielectric layer-metal layer-dielectric layer from top to bottom. The optical frequency selective surface of the invention is composed of a silicon oxide layer on a silicon oxide layer ₂ Periodic metal-dielectric thin film units on the substrate are composed, and the strong reflection and absorption characteristics of a specific metal-dielectric thin film on near infrared light are utilized, and the high visible light transmittance of a metal film with nano-scale thickness is utilized. The invention improves the electromagnetic performance of the optical frequency selective surface by reasonably controlling each dimension parameter, the kind of material and the structure of the metal-dielectric film in the structure.

Description

An Optical Frequency Selective Surface for Visible Light Transmission and Near Infrared Shielding

technical field

The invention relates to the technical field of optical frequency selective surfaces, in particular to an optical frequency selective surface shielding visible light through near-infrared rays.

Background technique

By designing subwavelength artificial structures, materials with specific electromagnetic responses can be synthesized, and such artificially designed materials are called metamaterials. Metamaterials are usually designed by arranging a set of regular subwavelength-sized small scatterers or apertures in a spatial region, with some special bulk electromagnetic properties, such as negative refractive index, reverse wave, inverse Doppler effect, etc.

Metasurface is a two-dimensional form of metamaterial. A metasurface is formed by arranging planar periodic subwavelength metal/dielectric unit structures on a dielectric substrate. Compared with metamaterials, the planarization of metasurfaces gives them the unique advantages of small size, thin thickness, and low loss. The use of metasurface structures can easily adjust electromagnetic waves in the sub-wavelength range, including parameters such as amplitude, phase, frequency, and polarization direction. Therefore, metasurfaces have great potential in the fields of wavefront shaping, frequency selection, and polarization direction conversion. Great application prospects.

Frequency Selective Surface (FSS) is a metasurface that can selectively reflect, absorb or transmit electromagnetic waves of specific frequency bands. Optical frequency selective surfaces refer to frequency selective surfaces that operate in the optical frequency band (electromagnetic wave frequency band from ultraviolet to infrared light, including visible light). In recent years, optical frequency selective surfaces have become a research hotspot, especially the research on frequency selective surfaces for energy-saving windows. Since ordinary glass does not have the ability to selectively transmit sunlight, while transmitting visible light, near-infrared light that carries a lot of heat also enters the room, resulting in a large amount of energy consumption for temperature regulation.

In the research field of optical frequency selective surfaces, the optical frequency selective surfaces that efficiently transmit visible light while shielding infrared waves still need further research.

Contents of the invention

The object of the present invention is to provide an optical frequency selective surface that shields visible light through near-infrared rays in order to overcome the deficiencies of the prior art. The optical frequency selective surface based on the metal-dielectric thin film of the present invention realizes higher visible light transmittance and better near-infrared shielding properties, so as to reduce unnecessary energy consumption.

In order to achieve the above-mentioned purpose of the invention, the present invention provides the following technical solutions:

The invention provides an optical frequency selective surface shielding visible light through near-infrared rays, comprising a substrate, a metal-dielectric film structure and an anti-reflection layer;

The metal-dielectric film structure from top to bottom is metal layer-dielectric layer-metal layer, dielectric layer-metal layer-dielectric layer or dielectric layer-metal layer-dielectric layer-metal layer-dielectric layer.

Preferably, the metal-dielectric film structure and the anti-reflection layer are on the upper surface of the substrate, and the metal-dielectric film structure is located in the middle of the anti-reflection layer.

Preferably, the material of the metal layer is copper, silver or gold; the material of the dielectric layer is titanium dioxide or indium tin oxide.

Preferably, the substrate is a silicon dioxide substrate.

Preferably, the material of the anti-reflection layer is polymethyl methacrylate.

Preferably, in the metal layer-dielectric layer-metal layer, the thickness of each metal layer is independently 27-33 nm, and the thickness of the dielectric layer is 8-12 nm.

Preferably, in the dielectric layer-metal layer-dielectric layer-metal layer-dielectric layer, the thickness of each dielectric layer is independently 28-32 nm, and the thickness of each metal layer is independently 18-22 nm.

Preferably, the thickness of the anti-reflection layer is 120-210 nm; the length and width of the metal-dielectric film structure are independently 150-240 nm.

Preferably, the length of the anti-reflection layer and the silicon dioxide substrate are the same; the width of the anti-reflection layer and the silicon dioxide substrate is the same; the length and width of the silicon dioxide substrate are independently 370-430 nm.

The beneficial effects of the present invention include:

1) The optical frequency selective surface of the present invention is made up of periodic metal-dielectric thin film units on the _SiO2 substrate, utilizes the strong reflection and absorption characteristics of specific metal-dielectric thin films to near-infrared light, and the properties of nanometer-scale thickness metal films High visible light transmission. The invention improves the electromagnetic performance of the optical frequency selective surface by rationally controlling each size parameter, the type of material and the structure of the metal-dielectric thin film in the structure. The near-infrared shielding performance of gold and copper of the present invention is stronger, and the visible light transmittance of silver is higher; Indium tin is higher. Gold, silver, copper, titanium dioxide and indium tin oxide of the present invention can improve the performance of the optical frequency selective surface of the present invention; the increase of the width of the metal-dielectric film will cause the reduction of visible light transmittance and the enhancement of near-infrared shielding ability, so it is necessary to Reasonable control of the width of the metal-dielectric film can enhance the near-infrared shielding ability while increasing the visible light transmittance.

2) According to the simulation results of the three-dimensional electromagnetic field simulation software CST, the optical frequency selective surface of the present invention has a relatively high transmittance to visible light (wavelength 400-760nm), which is more than 75%, up to 90%. The shielding rate to near-infrared light (wavelength 760-1300nm) is more than 50%, up to 80%. The metal-dielectric thin film in the optical frequency selective surface of the present invention adopts the structure of "dielectric layer-metal layer-dielectric layer-metal layer-dielectric layer", and when the metal material is selected from gold, silver or copper, and the dielectric material is selected from titanium dioxide, it can Optimizing the electromagnetic properties of optical frequency selective surfaces. The optical frequency selective surface of the present invention can also be used in optically transparent infrared cloaking windows of military equipment.

Description of drawings

Fig. 1 is the cell structure period of the optical frequency selective surface of embodiment 1;

Fig. 2 is the three-dimensional structural diagram of the optical frequency selective surface of embodiment 1, wherein, 1 is silicon dioxide substrate, 2 is polymethyl methacrylate layer, 3 is copper metal layer, 4 is indium tin oxide medium layer, 5 is a copper metal layer;

Fig. 3 is the electromagnetic wave transmittance curve in the range of 400-1300nm to the wavelength of the optical frequency selective surface of Example 1 simulated by the three-dimensional electromagnetic field simulation software CST;

Fig. 4 is the electromagnetic wave transmittance curve in the range of 400-1300nm to the wavelength of the optical frequency selective surface of Example 2 simulated by the three-dimensional electromagnetic field simulation software CST;

Fig. 5 is a curve of the electromagnetic wave transmittance of the optical frequency selective surface in the wavelength range of 400-1300 nm simulated by the three-dimensional electromagnetic field simulation software CST of Example 3.

Detailed ways

The invention provides an optical frequency selective surface shielding visible light through near-infrared rays, comprising a substrate, a metal-dielectric film structure and an anti-reflection layer;

The metal-dielectric film structure from top to bottom is metal layer-dielectric layer-metal layer, dielectric layer-metal layer-dielectric layer or dielectric layer-metal layer-dielectric layer-metal layer-dielectric layer.

In the present invention, the metal-dielectric film structure and the anti-reflection layer are preferably on the upper surface of the substrate, and the metal-dielectric film structure is preferably located in the middle of the anti-reflection layer.

In the present invention, the material of the metal layer is preferably copper, silver or gold; the material of the dielectric layer is preferably titanium dioxide or indium tin oxide.

In the present invention, the substrate is preferably a silicon dioxide substrate.

In the present invention, the material of the anti-reflection layer is preferably polymethyl methacrylate; as the anti-reflection layer, polymethyl methacrylate can reduce the impedance mismatch between the metal-dielectric film structure and the air.

In the present invention, the material of the optical frequency selective surface unit structure is optimized by the electromagnetic simulation software CST, and the material of the substrate, the metal-dielectric thin film structure and the anti-reflection layer of the present invention has better visible light transmittance and near-infrared ray shielding performance.

In the present invention, in the metal layer-dielectric layer-metal layer, the thickness of each metal layer is independently preferably 27-33 nm, more preferably 29-31 nm, more preferably 30 nm; the thickness of the dielectric layer is preferably 8-12 nm , more preferably 9 to 11 nm, more preferably 10 nm.

In the present invention, in the dielectric layer-metal layer-dielectric layer-metal layer-dielectric layer, the thickness of each dielectric layer is independently preferably 28-32 nm, more preferably 29-31 nm, more preferably 30 nm; each metal layer The thickness is independently preferably 18-22 nm, more preferably 19-21 nm, more preferably 20 nm.

In the present invention, in the dielectric layer-metal layer-dielectric layer, the thickness of each dielectric layer is independently preferably 28-32nm, more preferably 29-31nm, more preferably 30nm; the thickness of the metal layer is preferably 47-53nm, further Preferably it is 49-51 nm, More preferably, it is 50 nm.

In the present invention, the thickness of the anti-reflection layer is preferably 120-210 nm, more preferably 150-180 nm, more preferably 160-170 nm; the length and width of the metal-dielectric thin film structure are independently preferably 150-240 nm, More preferably, it is 180-210 nm, More preferably, it is 190-200 nm.

In the present invention, the anti-reflection layer and the silicon dioxide substrate have the same length; the anti-reflection layer and the silicon dioxide substrate have the same width; the independent length and width of the silicon dioxide substrate are preferably 370 to 430 nm, further Preferably it is 380-420 nm, More preferably, it is 390-400 nm.

In the present invention, the unit structures of the optical frequency selective surface are closely connected laterally and vertically, and are periodically arranged to form a two-dimensional plane; wherein, a large distance is kept between the metal-dielectric film structures to ensure high transmittance of visible light.

In the present invention, the thickness of the anti-reflection layer of the optical frequency selective surface unit structure, the thickness and width of each metal layer and dielectric layer, and the length of the silicon dioxide substrate are optimized by the electromagnetic simulation software CST. Metal-medium The increase of the width of the film will lead to the reduction of visible light transmittance and the enhancement of near-infrared shielding ability, so it is necessary to reasonably control the width of the metal-dielectric film to enhance the near-infrared shielding ability while improving the visible light transmittance; the size parameters of the present invention can be improved simultaneously. Visible light transmission and near-infrared shielding properties of optical frequency selective surfaces.

In the electromagnetic simulation software CST, the three structures of metal layer-dielectric layer-metal layer, dielectric layer-metal layer-dielectric layer or dielectric layer-metal layer-dielectric layer-metal layer-dielectric layer were respectively simulated and constructed. Parameter optimization to balance the electromagnetic performance of optical frequency selective surfaces in the visible and near-infrared bands.

The technical solutions provided by the present invention will be described in detail below in conjunction with the examples, but they should not be interpreted as limiting the protection scope of the present invention.

Example 1

An optical frequency selective surface that shields visible light through near-infrared rays, including a silicon dioxide substrate, a metal-dielectric film structure, and a polymethyl methacrylate anti-reflection layer; the metal-dielectric film structure and the anti-reflection layer are all on a silicon dioxide substrate On the upper surface of the bottom, the metal-dielectric thin film structure is in the middle of the anti-reflection layer; the metal-dielectric thin film structure is respectively a copper metal layer, an indium tin oxide dielectric layer, and a copper metal layer from top to bottom.

The thickness of the silicon dioxide substrate is 300nm, the length and width are 400nm, the thickness of the anti-reflection layer is 150nm, the length and width are 400nm; in the metal-dielectric thin film structure, the thickness of each metal layer is 30nm, and the dielectric The thickness of the layer is 10nm, and the length and width of the metal-dielectric film structure are both 180nm. The unit structure of each optical frequency selective surface is closely connected in the lateral direction and the longitudinal direction, and is arranged periodically.

The unit structure period of the optical frequency selective surface of the present embodiment is as shown in Figure 1, the length and width of the silicon dioxide substrate and the anti-reflection layer are both 400nm; the length and width of the metal-dielectric thin film structure are both w, and w is 180nm, the thickness t1 and t3 of the two copper metal layers are both 30nm, and the thickness t2 of the indium tin oxide dielectric layer is 10nm.

The three-dimensional structure diagram of the optical frequency selective surface of this embodiment is shown in Figure 2, in Figure 2, 1 is a silicon dioxide substrate, 2 is a polymethyl methacrylate layer, 3 is a copper metal layer, and 4 is an indium oxide The tin dielectric layer, 5 is a copper metal layer, and 3, 4, 5 are inside 2.

The three-dimensional electromagnetic field simulation software CST was used to simulate the transmittance curve of the optical frequency selective surface of this embodiment to the electromagnetic wave within the wavelength range of 400-1300 nm. The simulation results are shown in FIG. 3 .

Example 2

An optical frequency selective surface that shields visible light through near-infrared rays, including a silicon dioxide substrate, a metal-dielectric film structure, and a polymethyl methacrylate anti-reflection layer; the metal-dielectric film structure and the anti-reflection layer are all on a silicon dioxide substrate On the upper surface of the bottom, the metal-dielectric film structure is in the middle of the anti-reflection layer; the metal-dielectric film structure from top to bottom is titanium dioxide dielectric layer, gold metal layer, titanium dioxide dielectric layer, gold metal layer, titanium dioxide dielectric layer .

The thickness of the silicon dioxide substrate is 300nm, the length and width are 400nm, the thickness of the anti-reflection layer is 180nm, the length and width are 400nm; in the metal-dielectric film structure, the thickness of each metal layer is 20nm, each The thickness of the dielectric layer is 30nm, and the length and width of the metal-dielectric film structure are both 210nm. The unit structure of each optical frequency selective surface is closely connected in the lateral direction and the longitudinal direction, and is arranged periodically.

The three-dimensional electromagnetic field simulation software CST is used to simulate the transmittance curve of the optical frequency selective surface of this embodiment to the electromagnetic wave within the wavelength range of 400-1300 nm, and the simulation results are shown in FIG. 4 .

Example 3

An optical frequency selective surface that shields visible light through near-infrared rays, including a silicon dioxide substrate, a metal-dielectric film structure, and a polymethyl methacrylate anti-reflection layer; the metal-dielectric film structure and the anti-reflection layer are all on a silicon dioxide substrate On the upper surface of the bottom, the metal-dielectric film structure is in the middle of the anti-reflection layer; the metal-dielectric film structure from top to bottom is an indium tin oxide dielectric layer, a gold metal layer, an indium tin oxide dielectric layer, and a gold metal layer , Indium tin oxide dielectric layer.

The thickness of the silicon dioxide substrate is 300nm, the length and width are 400nm, the thickness of the anti-reflection layer is 180nm, the length and width are 400nm; in the metal-dielectric film structure, the thickness of each metal layer is 20nm, each The thickness of the dielectric layer is 30nm, and the length and width of the metal-dielectric film structure are both 210nm. The unit structures of each optical frequency selective surface are closely connected in the lateral and vertical directions, and are arranged periodically.

The three-dimensional electromagnetic field simulation software CST is used to simulate the transmittance curve of the optical frequency selective surface of this embodiment to the electromagnetic wave within the wavelength range of 400-1300 nm, and the simulation results are shown in FIG. 5 .

Example 4

An optical frequency selective surface that shields visible light through near-infrared rays, including a silicon dioxide substrate, a metal-dielectric film structure, and a polymethyl methacrylate anti-reflection layer; the metal-dielectric film structure and the anti-reflection layer are all on a silicon dioxide substrate On the upper surface of the bottom, the metal-dielectric film structure is in the middle of the anti-reflection layer; the metal-dielectric film structure from top to bottom is titanium dioxide dielectric layer, silver metal layer, titanium dioxide dielectric layer, silver metal layer, titanium dioxide dielectric layer .

The thickness of the silicon dioxide substrate is 290nm, the length and width are 380nm, the thickness of the anti-reflection layer is 170nm, the length and width are 380nm; in the metal-dielectric film structure, the thickness of each metal layer is 18nm, each The thicknesses of the dielectric layers are both 28nm, and the length and width of the metal-dielectric film structure are both 160nm. The unit structure of each optical frequency selective surface is closely connected in the lateral direction and the longitudinal direction, and is arranged periodically.

Example 5

An optical frequency selective surface that shields visible light through near-infrared rays, including a silicon dioxide substrate, a metal-dielectric film structure, and a polymethyl methacrylate anti-reflection layer; the metal-dielectric film structure and the anti-reflection layer are all on a silicon dioxide substrate On the upper surface of the bottom, the metal-dielectric film structure is in the middle of the anti-reflection layer; the metal-dielectric film structure from top to bottom is titanium dioxide dielectric layer, copper metal layer, titanium dioxide dielectric layer, copper metal layer, titanium dioxide dielectric layer .

The thickness of the silicon dioxide substrate is 310nm, the length and width are 420nm, the thickness of the anti-reflection layer is 200nm, the length and width are 420nm; in the metal-dielectric film structure, the thickness of each metal layer is 22nm, each The thickness of the dielectric layer is 32nm, and the length and width of the metal-dielectric film structure are both 225nm. The unit structure of each optical frequency selective surface is closely connected in the lateral direction and the longitudinal direction, and is arranged periodically.

Example 6

An optical frequency selective surface that shields visible light through near-infrared rays, including a silicon dioxide substrate, a metal-dielectric film structure, and a polymethyl methacrylate anti-reflection layer; the metal-dielectric film structure and the anti-reflection layer are all on a silicon dioxide substrate On the upper surface of the bottom, the metal-dielectric thin film structure is in the middle of the anti-reflection layer; the metal-dielectric thin film structure is respectively a titanium dioxide dielectric layer, a silver metal layer, and a titanium dioxide dielectric layer from top to bottom.

The thickness of the silicon dioxide substrate is 300nm, the length and width are 400nm, the thickness of the anti-reflection layer is 150nm, and the length and width are 400nm; in the metal-dielectric thin film structure, the thickness of the metal layer is 50nm, and the thickness of the dielectric layer The length and width of the metal-dielectric film structure are both 180nm. The unit structure of each optical frequency selective surface is closely connected in the lateral direction and the longitudinal direction, and is arranged periodically.

The near-infrared shielding performance of gold and copper of the present invention is stronger, and the visible light transmittance of silver is higher; Indium tin is higher, and the gold, silver, copper, titanium dioxide and indium tin oxide of the present invention can improve the performance of the optical frequency selective surface of the present invention. According to the simulation results of the three-dimensional electromagnetic field simulation software CST, the optical frequency selective surface of the present invention has a relatively high transmittance to visible light (wavelength 400-760nm), which is more than 75%, up to 90%. The shielding rate for near-infrared light (wavelength 760-1300nm) is over 50%, up to 80%. The metal-dielectric thin film in the optical frequency selective surface of the present invention adopts the structure of "dielectric layer-metal layer-dielectric layer-metal layer-dielectric layer", and when the metal material is selected from gold, silver or copper, and the dielectric material is selected from titanium dioxide, it can Optimizing the electromagnetic properties of optical frequency selective surfaces.

The above is only a preferred embodiment of the present invention, it should be pointed out that, for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications can also be made. It should be regarded as the protection scope of the present invention.

Claims (9)

1. An optical frequency selective surface for shielding visible light from near infrared light, comprising a substrate, a metal-dielectric thin film structure, and an anti-reflective layer;

the metal-dielectric film structure sequentially comprises a metal layer-dielectric layer-metal layer, a dielectric layer-metal layer-dielectric layer or a dielectric layer-metal layer-dielectric layer from top to bottom.

2. The optical frequency selective surface of claim 1, wherein the metal-dielectric thin film structure and the anti-reflective layer are on an upper surface of the substrate, the metal-dielectric thin film structure being in an interior intermediate position of the anti-reflective layer.

3. The optical frequency selective surface according to claim 1 or 2, wherein the metal layer is made of copper, silver or gold; the dielectric layer is made of titanium dioxide or indium tin oxide.

4. An optical frequency selective surface according to claim 3, wherein the substrate is a silica substrate.

5. An optical frequency selective surface according to claim 3, wherein the material of the anti-reflection layer is polymethyl methacrylate.

6. The optical frequency selective surface according to claim 4 or 5, wherein the thickness of each metal layer is independently 27-33 nm and the thickness of the dielectric layer is 8-12 nm.

7. The optical frequency selective surface according to claim 1 or 5, wherein the thickness of each dielectric layer is independently 28-32 nm and the thickness of each metal layer is independently 18-22 nm.

8. The optical frequency selective surface according to claim 7, wherein the thickness of the anti-reflection layer is 120-210 nm; the length and width of the metal-dielectric film structure are independently 150-240 nm.

9. The optical frequency selective surface of claim 8, wherein the antireflective layer and the silica substrate are the same length; the width of the antireflection layer is the same as that of the silicon dioxide substrate; the length and width of the silicon dioxide substrate are independently 370-430 nm.

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