阅读说明：本技术 一种基于3d打印光子晶体的制备方法、光子晶体 (Preparation method of photonic crystal based on 3D printing and photonic crystal ) 是由 朱朋飞 李勃 张伟喆 秦政 陈劲 于 2021-07-07 设计创作，主要内容包括：本发明公开了一种基于3D打印光子晶体及其制备方法,所述制备方法包括以下步骤：S1、制备浆料,所述浆料的弹性模量大于粘性模量,且具有粘弹逆变性,所述浆料由聚二甲基硅氧烷和陶瓷材料制成,其中,所述浆料分为浆料A和浆料B,浆料A的介电常数不等于浆料B的介电常数；S2、采用无膜直写3D打印设备将浆料A形成第一晶体层,将浆料B形成第二晶体层,其中,所述第一晶体层和第二晶体层堆叠形成木堆结构,得到光子晶体半成品；S3、将光子晶体半成品进行固化,得到光子晶体。本发明的制备方法,工艺简单,制备所得的光子晶体精度高,可实现不同频段太赫兹波的隐身,应用的波段可在10GHz～10THz范围。(The invention discloses a photonic crystal based on 3D printing and a preparation method thereof, wherein the preparation method comprises the following steps: s1, preparing a slurry, wherein the elastic modulus of the slurry is greater than the viscous modulus, the slurry has visco-elastic inverse transformation performance, the slurry is made of polydimethylsiloxane and a ceramic material, the slurry is divided into a slurry A and a slurry B, and the dielectric constant of the slurry A is not equal to that of the slurry B; s2, forming a first crystal layer from the slurry A and a second crystal layer from the slurry B by adopting a film-free direct-writing 3D printing device, wherein the first crystal layer and the second crystal layer are stacked to form a wood stack structure, and a photonic crystal semi-finished product is obtained; and S3, curing the photonic crystal semi-finished product to obtain the photonic crystal. The preparation method provided by the invention is simple in process, the prepared photonic crystal is high in precision, the stealth of terahertz waves of different frequency bands can be realized, and the applied wave band can be in the range of 10 GHz-10 THz.)

1. A preparation method based on 3D printing photonic crystals is characterized by comprising the following steps:

s1, preparing a slurry, wherein the elastic modulus of the slurry is greater than the viscous modulus, the slurry has visco-elastic inverse transformation performance, the slurry is made of polydimethylsiloxane and a ceramic material, the slurry is divided into a slurry A and a slurry B, and the dielectric constant of the slurry A is not equal to that of the slurry B;

s2, forming a first crystal layer from the slurry A and a second crystal layer from the slurry B by adopting a film-free direct-writing 3D printing device, wherein the first crystal layer and the second crystal layer are stacked to form a wood stack structure, and a photonic crystal semi-finished product is obtained;

and S3, curing the photonic crystal semi-finished product to obtain the photonic crystal.

2. The method for preparing the photonic crystal based on 3D printing according to claim 1, wherein the first crystal layer is composed of a plurality of first dielectric rods, the second crystal layer is composed of a plurality of second dielectric rods, the diameter of the first dielectric rods is 100-500 μm, the distance between the adjacent first dielectric rods is 300-700 μm, the diameter of the second dielectric rods is 100-500 μm, and the distance between the adjacent second dielectric rods is 300-700 μm.

3. The method for preparing photonic crystals based on 3D printing according to claim 1, wherein in step S2, the slurry is loaded into a cylinder of a film-free direct-writing 3D printing device, the working input air pressure of the film-free direct-writing 3D printing device is set to be 480-580 Kpa, and the working gas output is set to be 10-100 psi.

4. The method for preparing 3D printing-based photonic crystals according to claim 2, wherein the non-film direct writing 3D printing device has a working input pressure of 500 to 560Kpa and a working gas output of 30 to 80 psi.

5. The method for preparing photonic crystals based on 3D printing according to claim 1, wherein the ceramic material is barium titanate and/or zirconium oxide;

if the type of the ceramic material in the slurry A is the same as that of the ceramic material in the slurry B, the content of the ceramic material in the slurry A is greater than or less than that of the ceramic material in the slurry B, so that the slurry A and the slurry B with different dielectric constants are obtained; alternatively, the first and second electrodes may be,

if the type of the ceramic material in the slurry A is different from that of the ceramic material in the slurry B, the content of the ceramic material in the slurry A is equal to that of the ceramic material in the slurry B, so that the slurry A and the slurry B with different dielectric constants are obtained.

6. The preparation method of photonic crystals based on 3D printing according to claim 5, wherein the ceramic material in paste A and the ceramic material in paste B are both barium titanate, wherein the content of barium titanate in paste A is greater than or less than that of barium titanate in paste B, so as to obtain paste A and paste B with different dielectric constants.

7. The preparation method of photonic crystals based on 3D printing according to claim 6, wherein the mass fraction of barium titanate in slurry A is 20-50% and the mass fraction of barium titanate in slurry B is 30-60%.

8. The method for preparing photonic crystals based on 3D printing according to claim 6 or 7, wherein the barium titanate has an average particle size < 100nm and a density of 6.08g/cm³。

9. The method for preparing the photonic crystal based on 3D printing according to claim 1, wherein the total number of the first crystal layer and the second crystal layer is 4-12, and the first crystal layer and the second crystal layer are stacked in ABAB or AABB.

10. A photonic crystal comprising a first crystal layer and a second crystal layer stacked to form a wood stack structure; wherein the first crystal layer is composed of a plurality of first dielectric rods, the second crystal layer is composed of a plurality of second dielectric rods, the first dielectric rods are made of slurry A, the second dielectric layers are made of slurry B, the elastic modulus of the slurry A and the elastic modulus of the slurry B are greater than the viscous modulus, the slurry A and the slurry B have viscoelastic inversion, the slurry A and the slurry B are both made of polydimethylsiloxane and ceramic materials, and the dielectric constant of the slurry A is not equal to that of the slurry B.

Technical Field

The invention relates to the technical field of photonic crystals, in particular to a 3D printing-based photonic crystal preparation method and a photonic crystal.

Background

Terahertz (THz) waves refer to waves with frequencies of: 0.1 THz-10 THz, and the wavelength range is as follows: the terahertz wave has the double characteristics of both microwave and light wave, namely the penetrating power similar to microwave and the directivity similar to light wave, and has very strong complementary characteristics compared with the electromagnetic wave of other wave bands. Compared with microwave and millimeter wave, the THz detection technology can obtain higher resolution, and has outstanding anti-interference capability and unique anti-stealth capability; compared with laser, the THz technology has the advantages of wide field range, good searching capability, suitability for severe meteorological conditions and the like.

The photonic crystal is a periodic dielectric metamaterial structure with a photonic band gap, and the propagation of electromagnetic waves can be conveniently controlled by the photonic band gap characteristic of the photonic crystal. In order to realize the regulation and control of the THz wave band, the size of the photonic crystal is equivalent to that of the THz wave band, and the traditional processing mode is difficult to meet when the size of the photonic crystal with the size is prepared.

Chinese patent CN201110406205.6 discloses a method for preparing a multi-medium coupling three-dimensional photonic crystal, which adopts a gel injection molding method to prepare the multi-medium coupling photonic crystal, two different medium materials are respectively injected into each adjacent long column, and the long column corresponding to the upper layer is communicated with the long column corresponding to the lower layer. The method comprises the steps of firstly forming a long cylinder shell of a wood stack structure, and then injecting different medium materials, so that the process is complex, and the precision of the prepared photonic crystal is low; in addition, the width of the long column body formed by the method is difficult to reach the micron level, and the width of the dielectric rod formed by the correspondingly injected dielectric material after molding is also difficult to reach the micron level, so that the wave band of the photonic crystal prepared by the method can only be below 1 GHz.

The non-mould direct writing technology is suitable for direct writing printing of various ceramics, metals, macromolecules and biological materials. During the printing process of the materials, the materials are firstly prepared into slurry (Ink) with certain viscosity, the slurry is filled in a cylinder (Ink box) of a direct-writing printer, the slurry is extruded out from a needle at the bottom of the cylinder by certain external pressure, and the slurry is gradually stacked into a three-dimensional object with a certain shape structure according to the movement of a three-dimensional moving platform.

How to ensure that the paste with certain viscosity can flow and be extruded from the needle head under the pressure regulation effect in the direct-writing printing process, and the paste can be kept in a static state without flowing and collapsing after being extruded, is the research focus of the die-free direct-writing 3D printing technology.

Disclosure of Invention

The invention aims to solve the technical problem of providing a preparation method of a photonic crystal based on 3D printing, which has simple process, high precision of the prepared photonic crystal, and capability of realizing the stealth and modulation of terahertz waves in different frequency bands, wherein the applied wave bands can be in the range of 10 GHz-10 THz.

The invention also aims to solve the technical problem of providing a preparation method of photonic crystals based on 3D printing, which comprises the following steps:

s1, preparing a slurry, wherein the elastic modulus of the slurry is greater than the viscous modulus, the slurry has visco-elastic inverse transformation performance, the slurry is made of polydimethylsiloxane and a ceramic material, the slurry is divided into a slurry A and a slurry B, and the dielectric constant of the slurry A is not equal to that of the slurry B;

s2, forming a first crystal layer from the slurry A and a second crystal layer from the slurry B by adopting a film-free direct-writing 3D printing device, wherein the first crystal layer and the second crystal layer are stacked to form a wood stack structure, and a photonic crystal semi-finished product is obtained;

and S3, curing the photonic crystal semi-finished product to obtain the photonic crystal.

In an improvement of the above aspect, the first crystal layer is composed of a plurality of first dielectric rods, the second crystal layer is composed of a plurality of second dielectric rods, the diameter of each first dielectric rod is 100 to 500 μm, the distance between adjacent first dielectric rods is 300 to 700 μm, the diameter of each second dielectric rod is 100 to 500 μm, and the distance between adjacent second dielectric rods is 300 to 700 μm.

In an improvement of the above, in step S2, the slurry is loaded into a cartridge of the film-less direct-writing 3D printing apparatus, the working input air pressure of the film-less direct-writing 3D printing apparatus is set to 480 to 580Kpa, and the working gas output is set to 10 to 100 psi.

As an improvement of the scheme, the working input air pressure of the film-free direct-writing 3D printing device is 500-560 Kpa, and the working gas output is set to be 30-80 psi.

As an improvement of the above scheme, the ceramic material is barium titanate and/or zirconium oxide;

if the type of the ceramic material in the slurry A is the same as that of the ceramic material in the slurry B, the content of the ceramic material in the slurry A is greater than or less than that of the ceramic material in the slurry B, so that the slurry A and the slurry B with different dielectric constants are obtained; alternatively, the first and second electrodes may be,

if the type of the ceramic material in the slurry A is different from that of the ceramic material in the slurry B, the content of the ceramic material in the slurry A is equal to that of the ceramic material in the slurry B, so that the slurry A and the slurry B with different dielectric constants are obtained.

In an improvement of the above scheme, the ceramic material in slurry a and the ceramic material in slurry B are both barium titanate, wherein the content of barium titanate in slurry a is greater than or less than the content of barium titanate in slurry B, so as to obtain slurry a and slurry B with different dielectric constants.

As an improvement of the scheme, the mass fraction of barium titanate in the slurry A is 20-50%, and the mass fraction of barium titanate in the slurry B is 30-60%.

As an improvement of the scheme, the barium titanate has the average particle size of less than 100nm and the density of 6.08g/cm³。

As an improvement of the scheme, the total number of the first crystal layer and the second crystal layer is 4-12, wherein the first crystal layer and the second crystal layer are stacked in an ABAB or AABB mode.

Correspondingly, the invention also provides a photonic crystal, which comprises a first crystal layer and a second crystal layer, wherein the first crystal layer and the second crystal layer are stacked to form a wood stack structure; wherein the first crystal layer is composed of a plurality of first dielectric rods, the second crystal layer is composed of a plurality of second dielectric rods, the first dielectric rods are made of slurry A, the second dielectric layers are made of slurry B, the elastic modulus of the slurry A and the elastic modulus of the slurry B are greater than the viscous modulus, the slurry A and the slurry B have viscoelastic inversion, the slurry A and the slurry B are both made of polydimethylsiloxane and ceramic materials, and the dielectric constant of the slurry A is not equal to that of the slurry B.

The implementation of the invention has the following beneficial effects:

the elastic modulus of the invention is larger than the viscous modulus, and the slurry with visco-elastic inverse transformation can be directly formed by a non-mode direct-writing 3D printing technology, and the filament shape is kept unchanged after extrusion, and meanwhile, the three-dimensional structure has good flexibility and ductility after solidification.

The invention adopts the non-mode direct-writing forming technology to prepare the photonic crystal, not only can prepare the photonic crystal with high precision, but also can enable the dielectric rod forming the photonic crystal to reach the micron level, thereby improving the application waveband range of the photonic crystal.

The photonic crystal is prepared by adopting slurries with different dielectric constants so as to realize the stealth and modulation of terahertz waves in specific frequency bands; in addition, the photonic crystal is prepared by adopting the slurries with different dielectric constants, and can realize the scattering of the terahertz wave in a specific frequency band so as to realize the stealth and modulation of the terahertz waves in different frequency bands.

Drawings

FIG. 1 is a flow chart of the preparation of photonic crystals based on 3D printing according to the present invention;

FIG. 2 is a perspective view of the present invention based on 3D printed photonic crystals;

FIG. 3 is a first method of stacking a first crystalline layer and a second crystalline layer of the present invention;

fig. 4 is a second method of stacking the first crystal layer and the second crystal layer according to the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings. It is only noted that the invention is intended to be limited to the specific forms set forth herein, including any reference to the drawings, as well as any other specific forms of embodiments of the invention.

Referring to fig. 1, the preparation method of the photonic crystal based on 3D printing provided by the invention comprises the following steps:

s1, preparing a slurry, wherein the elastic modulus of the slurry is greater than the viscous modulus, the slurry has visco-elastic inverse transformation performance, the slurry is made of polydimethylsiloxane and a ceramic material, the slurry is divided into a slurry A and a slurry B, and the dielectric constant of the slurry A is not equal to that of the slurry B;

the photonic crystal is prepared by adopting slurries with different dielectric constants so as to realize the stealth and modulation of terahertz waves in specific frequency bands; in addition, the photonic crystal is prepared by adopting the slurries with different dielectric constants, and can realize the scattering of the terahertz wave in a specific frequency band so as to realize the stealth and modulation of the terahertz waves in different frequency bands.

It should be noted that the elastic modulus of the paste is greater than the viscous modulus in order to ensure that the paste can be direct-written without a film and that the paste can maintain the shape of the strands without collapse after extrusion. If the elastic modulus of the pulp is less than the viscous modulus, the pulp is always in a flowing state and cannot maintain the wood heap structure. In addition, as the pressure in the barrel is increased, when a certain pressure value is exceeded, the slurry can be extruded from the needle head, when the slurry is extruded from the needle head, the shear pressure disappears, the slurry has visco-elastic inversion, the elastic modulus can return to a platform section (the elastic modulus is larger than the viscous modulus), and the slurry can keep the filament shape after extrusion unchanged.

Because the polydimethylsiloxane has the viscoelastic inversion characteristic caused by shear stress, the polydimethylsiloxane is used as the base material of the slurry, so that the slurry can be directly formed by a mode-free direct-writing 3D printing technology, and the three-dimensional structure after curing has good flexibility and ductility.

However, the dielectric constant of the polydimethylsiloxane in the THz wave band is low and is only about 2, so that the ceramic material with high dielectric constant is selected to be uniformly dispersed in the polydimethylsiloxane to prepare the slurry. The photonic crystal of the invention provides flexible deformability by polydimethylsiloxane and dielectric capability by ceramic materials, so that the photonic crystal of the invention generates better response to THz waves.

It should be noted that the kind of polydimethylsiloxane plays an important role in the performance of the paste, and particularly, the kind of polydimethylsiloxane affects the elastic modulus and viscous modulus of the paste, thereby affecting whether the paste can maintain the shape of lines without collapse after printing.

Preferably, the polydimethylsiloxane has a viscosity of 10000 to 50000, a relative density of 0.971 to 0.978, and a dielectric constant of 2.80 to 2.85.

In addition, the kind of polydimethylsiloxane also affects the dispersion effect of the ceramic material, and if the viscosity of polydimethylsiloxane is more than 50000, the ceramic material is difficult to be uniformly dispersed therein; if the viscosity of the polydimethylsiloxane is less than 10000, it is difficult for the paste to maintain the shape of the line without collapse after printing.

Preferably, the ceramic material is barium titanate and/or zirconium oxide. In order to further improve the quality of the dielectric rod, enhance the strong Bragg scattering of the photonic crystal and the absorption of a specific wave band, it is preferable that the barium titanate has an average particle size of less than 100nm and a densityIs 6.08g/cm³。

The invention can prepare the slurry A and the slurry B with different dielectric constants by adjusting the content and the type of the ceramic material.

For example, if the kind of the ceramic material in the slurry a of the present invention is the same as that of the ceramic material in the slurry B, the slurry a and the slurry B having different dielectric constants can be prepared by adjusting the content of the ceramic material in the slurry a and the content of the ceramic material in the slurry B. Alternatively, if the content of the ceramic material in the slurry a is equal to the content of the ceramic material in the slurry B, the ceramic material in the slurry a and the ceramic material in the slurry B may be selected from different kinds to prepare the slurry a and the slurry B having different dielectric constants.

If the ceramic material in the slurry A is barium titanate and the ceramic material in the slurry B is barium titanate, the type of the ceramic material in the slurry A is the same as that of the ceramic material in the slurry B; or if the ceramic material in the slurry a is zirconia and the ceramic material in the slurry B is zirconia, the kind of the ceramic material in the slurry a is the same as that of the ceramic material in the slurry B; or, if the ceramic materials in the slurry a are barium titanate and zirconium oxide and the ceramic materials in the slurry B are barium titanate and zirconium oxide, the kind of the ceramic materials in the slurry a is the same as that of the ceramic materials in the slurry B.

If the ceramic material in the slurry A is barium titanate and the ceramic material in the slurry B is zirconium oxide, the type of the ceramic material in the slurry A is different from that of the ceramic material in the slurry B; or if the ceramic material in the slurry a is zirconia and the ceramic material in the slurry B is barium titanate and zirconia, the kind of the ceramic material in the slurry a is different from that of the ceramic material in the slurry B; or, if the ceramic material in the slurry a is barium titanate and zirconium oxide, and the ceramic material in the slurry B is barium titanate, the kind of the ceramic material in the slurry a is different from that in the slurry B.

Specifically, the ceramic material in the slurry a and the ceramic material in the slurry B are both barium titanate, and the content of barium titanate in the slurry a is greater than or less than the content of barium titanate in the slurry B, so that the slurry a and the slurry B with different dielectric constants can be prepared.

Or, the ceramic material in the slurry a is barium titanate, and the ceramic material in the slurry B is zirconium oxide, so that the content of barium titanate in the slurry a is equal to the content of zirconium oxide in the slurry B, and the slurry a and the slurry B with different dielectric constants can also be prepared.

It should be noted that the content of the ceramic material affects the viscosity and modulus of the slurry, and when the slurry is extruded from the needle, in order to ensure the same extrusion rate, a larger extrusion pressure is required, which affects the uniformity of the dielectric rod. Preferably, the content of the ceramic material in the slurry a and the slurry B is less than 90%.

In the invention, the Bragg scattering of the photonic crystal can be further improved by adjusting the content of the ceramic materials in the slurry A and the slurry B. Preferably, the mass fraction of the ceramic material in the slurry A is 20-50%, and the mass fraction of the ceramic material in the slurry B is 30-60%.

Preferably, the ceramic materials in the slurry A and the slurry B are barium titanate, the mass fraction of the barium titanate in the slurry A is 20-50%, and the mass fraction of the barium titanate in the slurry B is 30-60%.

S2, forming a first crystal layer from the slurry A and a second crystal layer from the slurry B by adopting a film-free direct-writing 3D printing device, wherein the first crystal layer and the second crystal layer are stacked to form a wood stack structure, and a photonic crystal semi-finished product is obtained;

specifically, referring to fig. 2, a film-free direct-writing 3D printing device is adopted to form the slurry a into a first crystal layer 11, form the slurry B into a second crystal layer 12, and stack the first crystal layer 11 and the second crystal layer 12 to form a wood stack structure, so as to obtain a photonic crystal semi-finished product. Wherein the first crystal layer 11 is composed of a plurality of first dielectric rods and the second crystal layer 12 is composed of a plurality of second dielectric rods.

The dielectric rod formed by the existing gel injection molding method has low precision and cannot reach micron, so that the wave band of the photonic crystal prepared by the existing method can only be below 1GHz, and cannot reach 1 THz. The invention adopts the non-mode direct-writing forming technology to prepare the photonic crystal, not only can prepare the photonic crystal with high precision, but also can enable the dielectric rod forming the photonic crystal to reach the micron level, thereby improving the application waveband range of the photonic crystal.

The invention improves the performance of the photonic crystal by improving the structure of the photonic crystal besides improving the performance of the photonic crystal by adopting the sizing agents (the sizing agent A and the sizing agent B) with different dielectric constants.

The structural parameters of the photonic crystal comprise the spacing D of the dielectric rods, the diameter D of the dielectric rods and the period height h of the dielectric rods in the layer-by-layer stacking direction, and the parameters can have certain influence on the band gap position of the photonic crystal. The wavelength of the electromagnetic wave is λ, the pitch of the dielectric rods is d, the frequency fn corresponding to the photonic bandgap is d/λ, the real frequency f is c/λ, and c is the speed of light, that is, the real frequency f is 300fn/d, the unit of d is μm, and the unit of f is THz. From the above formula, the distance d of the dielectric rods has an influence on the band gap of the photonic crystal.

In addition, the photonic band gap can only appear within a certain range of the period height h, and when the diameter of the dielectric rod is fixed, the interval of the dielectric rod is enlarged, so that the range of the period height of the photonic band gap is enlarged.

Preferably, the diameter of the first dielectric rod is 100-500 μm, and the distance is 300-700 μm; the diameter of the second dielectric rod is 100-500 mu m, and the distance is 300-700 mu m.

The total number of layers of the first crystal layer and the second crystal layer has certain influence on Bragg scattering of the photonic crystal, absorption of a specific waveband and invisibility of terahertz electromagnetic waves of different frequency bands.

Preferably, the total number of the first crystal layer and the second crystal layer is 4-12, wherein the first crystal layer and the second crystal layer are stacked in an ABAB or AABB manner. If the total number of the first crystal layer and the second crystal layer is less than 4, the effect cannot be achieved; if the total number of layers of the first crystal layer and the second crystal layer is greater than 12, the effect improvement is limited, but the cost is increased. Therefore, the total number of layers of the first crystal layer and the second crystal layer is 4-12 in combination with the filtering effect and the economy.

It should be noted that for an ideal wood stack structure, the height w of each layer and the diameter D of the media rod are identical, but in the actual printing process, because of the weight of the slurry to be supported after extrusion, the height of each layer is generally set to be slightly less than the diameter D of the media rod to ensure the integrity of the printed structure after extrusion.

It should be noted that two parameters of the working input air pressure and the working gas output of the film-less direct-writing 3D printing device play an important role in the formation of the first media rod and the second media rod, and directly determine whether the paste a and the paste B can be extruded from the barrel and whether the extrusion speed is constant. Wherein these two parameters are related to the material properties of slurry a and slurry B.

Specifically, in step S2, the slurry a and the slurry B are respectively loaded into two cartridges of the film-less direct-writing 3D printing apparatus, the working input air pressure of the film-less direct-writing 3D printing apparatus is set to 480 to 580Kpa, and the working gas output is set to 10 to 100 psi.

Preferably, the working input air pressure of the film-free direct-writing 3D printing device is 500-560 Kpa, and the working gas output is set to be 30-80 psi, so that the paste A and the paste B are not extruded too fast, and the shapes of the first medium rod and the second medium rod are ensured while the first medium rod and the second medium rod are extruded smoothly.

Preferably, the inner diameter of a needle head of the film-free direct-writing 3D printing equipment is 100-200 mu m. Wherein, the size of the inner diameter of the needle head determines the thickness of the photon medium rod.

The slurry a and the slurry B were extrusion molded at normal temperature. If the temperature is too high, the lattice phases of the first dielectric rod and the second dielectric rod are influenced, so that Bragg scattering of the photonic crystal is influenced, absorption of a specific waveband is influenced, and stealth of the photonic crystal to terahertz electromagnetic waves of different frequency bands is further influenced.

The application adopts the film-free direct-writing 3D printing equipment, not only can form the medium rods with the diameter of 100-500, but also can control the distance between the adjacent medium rods to be 300-700 mu m. The diameter and the distance of the dielectric rods forming the crystal layer play an important role in the absorption effect of the photonic crystal on a specific waveband and the stealth effect of terahertz electromagnetic waves of different frequency bands. If the diameter and the spacing of the photonic dielectric rods are smaller than the above range, the applied waveband cannot reach 10 GHz-10 THz.

Specifically, the first crystal layer is composed of a plurality of first dielectric rods, and the second crystal layer is composed of a plurality of second dielectric rods. Preferably, the first dielectric rods are parallel to each other, and the second dielectric rods are also parallel to each other. Further preferably, referring to fig. 3, the first dielectric rods 111 of the first crystal layers of two adjacent layers are vertically stacked with each other, and the second dielectric rods 112 of the second crystal layers of two adjacent layers are vertically stacked with each other; referring to fig. 4, the first dielectric rod 111 and the second dielectric rod 112 of the first crystal layer and the second crystal layer of the adjacent two layers are vertically stacked with each other.

And S3, curing the photonic crystal semi-finished product to obtain the photonic crystal.

Preferably, the curing temperature is 75-85 ℃, and the curing time is 1.5-2.5 hours.

Correspondingly, the invention also provides a photonic crystal, which comprises a first crystal layer and a second crystal layer, wherein the first crystal layer and the second crystal layer are stacked to form a wood stack structure; wherein the first crystal layer is composed of a plurality of first dielectric rods, the second crystal layer is composed of a plurality of second dielectric rods, the first dielectric rods are made of slurry A, the second dielectric layers are made of slurry B, the elastic modulus of the slurry A and the elastic modulus of the slurry B are greater than the viscous modulus, the slurry A and the slurry B have viscoelastic inversion, the slurry A and the slurry B are both made of polydimethylsiloxane and ceramic materials, and the dielectric constant of the slurry A is not equal to that of the slurry B.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.