Double-forbidden band opening and closing controllable plasma photonic crystal structure

Abstract

The invention relates to a double-forbidden band opening and closing controllable plasma photonic crystal structure, and belongs to the technical field of photonic crystals. The double-forbidden band opening and closing controllable plasma photonic crystal structure comprises a plurality of scattering media, and each scattering medium comprises a plasma and a medium tube wrapping the surface of the plasma; the plurality of scattering media are arranged in the background medium, and the period length of the scattering media in the horizontal direction is 49-51mm; and the relative dielectric constant of the dielectric tube is 9-13. Special lattice and dielectric tube relative dielectric constant distribution is adopted, two forbidden bands meeting requirements are excavated, evolution curves of center frequencies f11 and f12 of the forbidden bands along with plasma density can intersect with evolution curves of two full-transparent frequencies f01 and f02 respectively, the intersection point corresponds to the same plasma density, the two forbidden bands are controlled to be opened or closed at the same time, and the two forbidden bands are controlled to be opened or closed at the same time. Therefore, the function which a traditional photonic crystal or a plasma photonic crystal does not have is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of photonic crystals, and in particular relates to a plasma photonic crystal structure with controllable opening and closing of double-bandgap. Background Art

[0002] Photonic crystals are a type of artificial material with periodic structure, and there is a transmission bandgap in their transmission spectrum. When the frequency of the electromagnetic wave is in the bandgap, the photonic crystal can cut off the propagation of the electromagnetic wave, while the electromagnetic wave with a frequency outside the bandgap can propagate through the photonic crystal. Therefore, photonic crystals have a filtering function. Based on this function, defects such as linear defects or point defects can be introduced into the photonic crystal, and the electromagnetic wave can be localized in the defect through the bandgap, thereby further regulating the electromagnetic wave. It can be seen that the bandgap is the cornerstone of photonic crystals to regulate electromagnetic waves, and the adjustable bandgap technology has become an important technology in the field of photonic crystals.

[0003] Generally, the bandgap is adjusted by modifying the parameters of the photonic crystal. The main methods include: changing the lattice, changing the medium refractive index, changing the geometric size, destroying the lattice, etc. Among them, filling the photonic crystal with plasma is an important method. This structure combining photonic crystal and plasma is called plasma photonic crystal.

[0004] The bandgap of plasma photonic crystals is dynamically adjustable because changing the plasma density can affect the plasma dielectric constant: increasing the plasma density can reduce the dielectric constant, while reducing the plasma density has the opposite effect. For most existing plasma photonic crystal structures, increasing the plasma density will cause the overall bandgap to move toward higher frequencies, while the bandgap width will increase slightly. Based on these plasma photonic crystal structures, various adjustable microwave devices can be designed, such as waveguides, antennas, filters, etc.

[0005] However, in practical applications, it may be necessary to open or close the bandgap without affecting the electromagnetic waves outside the bandgap, that is, to control the propagation or non-propagation of electromagnetic waves in a wider frequency band. Existing technology can open or close a bandgap by adjusting the plasma density. However, if you want to open or close two bandgap at the same time, the existing plasma photonic crystal structure cannot meet the demand. Summary of the invention

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the problem that the plasma photonic crystal structure in the prior art cannot open or close two forbidden bands at the same time.

[0007] To solve the above technical problems, the present invention provides a dual-bandgap open-and-close controllable plasma photonic crystal structure, which can open or close two bandgap states at the same time, thereby realizing the switching between the propagation and non-propagation states of electromagnetic waves within an ultra-wide frequency band.

[0008] The present invention aims to provide a dual-bandgap opening and closing controllable plasma photonic crystal structure, comprising a plurality of scattering media, each of which comprises plasma and a medium tube wrapped on the surface of the plasma; the plurality of scattering media are arranged in a background medium, and the period length of the scattering medium along the horizontal direction is 49mm-51mm, for example, 49mm, 49.1mm, 49.2mm, 49.3mm, 49.4mm, 49.5mm, 49.6mm, 49.7mm, 49.8mm, 49.9mm, 50mm, 50.1mm, 50.2mm, 50.3mm, 50.4mm, 50.5mm, 50.6mm , 50.7mm, 50.8mm, 50.9mm, 51mm and so on; the relative dielectric constant of the dielectric tube is 9-13, for example, it can be 9, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 10, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9, 11, 11.1, 11.2, 11.3, 11.4, 11.5, 11.6, 11.7, 11.8, 11.9, 12, 12.1, 12.2, 12.3, 12.4, 12.5, 12.6, 12.7, 12.8, 12.9, 13 and so on.

[0009] In one embodiment of the present invention, the periodic length of the scattering medium along the vertical direction is 20mm-40mm, for example, it can be 20mm, 21mm, 22mm, 23mm, 24mm, 25mm, 26mm, 27mm, 28mm, 29mm, 30mm, 31mm, 32mm, 33mm, 34mm, 35mm, 36mm, 37mm, 38mm, 39mm, 40mm and the like.

[0010] In one embodiment of the present invention, the scattering medium

[0011] In one embodiment of the present invention, the arrangement is a periodic arrangement of lattice.

[0012] In one embodiment of the present invention, the pattern of the periodic arrangement of the lattices is a tetragonal lattice.

[0013] In one embodiment of the present invention, the radius of the plasma is 6 mm-7 mm, for example, it can be 6.1 mm, 6.2 mm, 6.3 mm, 6.4 mm, 6.5 mm, 6.6 mm, 6.7 mm, 6.8 mm, 6.9 mm, 7 mm, etc.

[0014] In one embodiment of the present invention, the thickness of the medium tube is 1 mm-2 mm, for example, it can be 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2 mm, etc.

[0015] In one embodiment of the present invention, the material of the dielectric tube is an insulating material.

[0016] In one embodiment of the present invention, the background medium is selected from air or an insulating medium.

[0017] In one embodiment of the present invention, the relative dielectric constant of the insulating medium is 1-2, for example, it can be 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, etc.

[0018] In one embodiment of the present invention, the plasma has a density of 0-10×10 11 cm -3 Adjustable range.

[0019] In one embodiment of the present invention, the effective impedance of the scattering medium is equal to the impedance of the background medium at a certain frequency f0. In this case, the electromagnetic wave will pass through the photonic crystal with a transmittance of 100%. At the same time, if the center frequency f1 of the bandgap is equal to f0, then according to the principle that the electromagnetic wave must pass through the photonic crystal, the bandgap will be closed. Both f0 and f1 are related to the lattice and relative dielectric constant distribution of the photonic crystal. In practice, by adjusting the relative dielectric constant, f0 and f1 can be changed at the same time, and the change curves of the two may intersect. By selecting the relative dielectric constant corresponding to the intersection, the bandgap with a center frequency of f0 can be closed.

[0020] In one embodiment of the present invention, plasma is a dispersive medium, which causes the original frequency f0 to split into two full-transmission frequencies f01 and f02, corresponding to two 100% transmission frequencies. On this basis, if there are two center frequencies of the forbidden band, f11 and f12, whose curves of evolution with plasma density respectively intersect with the evolution curve of, and the intersection point corresponds to the same plasma density, then in principle, the two forbidden bands can be simultaneously regulated to open or close by plasma.

[0021] The technical solution of the present invention has the following advantages over the prior art:

[0022] The dual-bandgap opening and closing controllable plasma photonic crystal structure of the present invention adopts a special lattice and dielectric tube relative dielectric constant distribution, and excavates two bandgap that meet the requirements, and the evolution curves of the center frequencies f11 and f12 with the plasma density can intersect with the evolution curves of the two full-transmission frequencies f01 and f02 respectively, and the intersection corresponds to the same plasma density. Finally, a new plasma photonic crystal structure is proposed, which can control the two bandgap to be opened or closed at the same time, thereby realizing functions that traditional photonic crystals or plasma photonic crystals do not have. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0024] Figure 1 It is a schematic diagram of the plasma photonic crystal structure with controllable double-bandgap opening and closing according to the present invention;

[0025] Figure 2 : is the transmission spectrum of the plasma photonic crystal structure in the test example of the present invention; wherein (a) is Example 1, (b) is Comparative Example 1, and (c) is Comparative Example 2;

[0026] Explanation of the reference numerals: 1 - insulating medium tube, 2 - plasma, 3 - background medium. DETAILED DESCRIPTION

[0027] The present invention is further described below in conjunction with specific embodiments so that those skilled in the art can better understand the present invention and implement it. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. It should be understood that the specific embodiments are only used to explain the present invention, but the embodiments are not intended to limit the present invention.

[0028] In the present invention, unless otherwise explained, technical and scientific terms used in the present invention have the same meanings as commonly understood by those skilled in the art to which the present invention belongs.

[0029] In the present invention, unless otherwise stated, the term "and / or" used in the present invention includes any and all combinations of one or more of the associated listed items.

[0030] In the present invention, unless otherwise stated, the experimental methods used in the embodiments of the present invention are conventional methods unless otherwise stated, and the materials, reagents, etc. used are all commercially available unless otherwise stated.

[0031] Example 1

[0032] Reference Figure 1As shown, the dual-bandgap opening and closing controllable plasma photonic crystal structure of this embodiment includes a plurality of scattering media, each of which includes a plasma 2 and a medium tube 1 wrapped around the surface of the plasma 2; the plurality of scattering media are arranged in a background medium 3 according to a tetragonal lattice periodicity, the period length of the scattering medium along the horizontal direction (x direction) is L, and the number of periods is 6; the period length along the vertical direction (y direction) is H, and the number of periods is 3; L and H are 50 mm and 20 mm, respectively;

[0033] Among them, the radius of the plasma is 6.5mm;

[0034] The thickness of the dielectric tube is 1 mm, the material is insulating material, and the relative dielectric constant is 13;

[0035] The background medium is selected from air, which has a relative dielectric constant of about 1.

[0036] Comparative Example 1 is basically the same as Example 1, except that the period length along the horizontal direction (x direction) is different, as follows:

[0037] The plasma photonic crystal structure of this comparative example includes a plurality of scattering media, each of which includes a plasma 2 and a medium tube 1 wrapped around the surface of the plasma 2; the plurality of scattering media are arranged in a background medium 3 according to a tetragonal lattice periodicity, the period length of the scattering media along the horizontal direction (x direction) is L, and the number of periods is 6; the period length along the vertical direction (y direction) is H, and the number of periods is 3; L and H are 45 mm and 20 mm respectively;

[0038] Among them, the radius of the plasma is 6.5mm;

[0039] The thickness of the dielectric tube is 1 mm, the material is insulating material, and the relative dielectric constant is 13;

[0040] The background medium is selected from air, which has a relative dielectric constant of about 1.

[0041] Comparative Example 2 is basically the same as Example 1, except that the relative dielectric constant of the dielectric tube is different, as follows:

[0042] The plasma photonic crystal structure of this comparative example includes a plurality of scattering media, each of which includes a plasma 2 and a medium tube 1 wrapped around the surface of the plasma 2; the plurality of scattering media are arranged in a background medium 3 according to a tetragonal lattice periodicity, the period length of the scattering media along the horizontal direction (x direction) is L, and the number of periods is 6; the period length along the vertical direction (y direction) is H, and the number of periods is 3; L and H are 50 mm and 20 mm, respectively;

[0043] Among them, the radius of the plasma is 6.5mm;

[0044] The thickness of the dielectric tube is 1 mm, the material is insulating material, and the relative dielectric constant is 8;

[0045] The background medium is selected from air, which has a relative dielectric constant of about 1.

[0046] Test Case

[0047] Control the incident electromagnetic wave along Figure 1 The electric field component oscillates along the z direction ( Figure 1 In the example 1 and the comparative example 1-2, the transmission spectra of the plasma photonic crystal structures are as follows: Figure 2 As shown. Figure 2 (a) It can be seen that when the plasma density is 0, there is a bandgap at 2.5 GHz and 4.9 GHz, as shown by the dotted lines. When the plasma density is adjusted to 4×10 11 cm -3 When , the two forbidden bands disappear at the same time, and the transmission spectrum presents a horizontal straight line close to 0 decibels, as shown by the solid line. This shows that under the parameter design of Example 1, the evolution curves of the two forbidden band center frequencies with plasma density and the evolution curves of the two full transmission frequencies intersect with each other, and the two intersection points correspond to the same plasma density value. Figure 2 (b) It can be seen that when the plasma density is 0, there is a bandgap at 2.7 GHz and 5.3 GHz, as shown by the dotted lines. When the plasma density is adjusted to 4.7×10 11 cm -3 When , the first forbidden band can be closed, while the second forbidden band is enhanced, as shown by the solid line. This is in contrast to the results of Example 1. This shows that under the parameter design of Comparative Example 1, it is impossible to simultaneously control the opening and closing of the two forbidden bands. Figure 2 (c) It can be seen that when the plasma density is 0, there is a bandgap at 2.6 GHz and 5.3 GHz, as shown by the dotted lines. When the plasma density is adjusted to 2.5×10 11 cm -3 , the first band gap can be closed, but the second band gap cannot be closed, as shown by the dot-dash line. When the plasma density is further increased to 4×10 11 cm -3 When , the second forbidden band can be closed, but the first forbidden band is reopened, as shown by the solid line. This shows that under the parameter design of comparative example 2, it is impossible to simultaneously control the opening and closing of the two forbidden bands.

[0048] This is because the effective impedance of the scattering medium is equal to the impedance of the background medium at certain frequencies f0. In this case, the electromagnetic wave will pass through the photonic crystal with a transmittance of 100%. At the same time, if the center frequency f1 of the bandgap is equal to f0, then according to the principle that the electromagnetic wave must pass through the photonic crystal, the bandgap will be closed. Both f0 and f1 are related to the lattice and relative dielectric constant distribution of the photonic crystal. In practice, by adjusting the relative dielectric constant, f0 and f1 can be changed at the same time, and the change curves of the two may intersect. Selecting the relative dielectric constant corresponding to the intersection point can close the bandgap with a center frequency of f0.

[0049] Plasma is a dispersive medium, which causes the original frequency f0 to split into two full-transmission frequencies f01 and f02, corresponding to two 100% transmission frequencies. On this basis, if there are two center frequencies of the forbidden bands, f11 and f12, whose curves of evolution with plasma density respectively intersect with the evolution curves of the two full-transmission frequencies f01 and f02, and the intersection point corresponds to the same plasma density, then in principle, the two forbidden bands can be simultaneously controlled by plasma to open or close.

[0050] The plasma photonic crystal structure of the embodiment realizes the function of opening or closing two forbidden bands at the same time through the special lattice and relative dielectric constant distribution of the dielectric tube. The evolution curves of the center frequencies f11 and f12 with the plasma density can intersect with the evolution curves of the two full-transmission frequencies f01 and f02 respectively, and the intersection corresponds to the same plasma density.

[0051] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from them are still within the protection scope of the invention.

Claims

1. A dual-bandgap opening and closing controllable plasma photonic crystal structure, characterized in that: It comprises a plurality of scattering media, each of which comprises plasma and a dielectric tube wrapped around the surface of the plasma; the plurality of scattering media are arranged in a background medium, and the period length of the scattering media along the horizontal direction is 49 mm-51 mm; the relative dielectric constant of the dielectric tube is 9-13.

2. The dual-bandgap opening and closing controllable plasma photonic crystal structure according to claim 1, characterized in that: The period length of the scattering medium along the vertical direction is 20 mm-40 mm.

3. The dual-bandgap opening and closing controllable plasma photonic crystal structure according to claim 1, characterized in that: The arrangement is a periodic arrangement of lattice.

4. The dual-bandgap opening and closing controllable plasma photonic crystal structure according to claim 1, characterized in that: The pattern of the periodic arrangement of the dot matrix is ​​a tetragonal lattice.

5. The dual-bandgap opening and closing controllable plasma photonic crystal structure according to claim 1, characterized in that: The radius of the plasma is 6 mm-7 mm.

6. The dual-bandgap opening and closing controllable plasma photonic crystal structure according to claim 1, characterized in that: The thickness of the medium tube is 1 mm-2 mm.

7. The dual-bandgap opening and closing controllable plasma photonic crystal structure according to claim 1, characterized in that: The material of the medium pipe is insulating material.

8. The dual-bandgap opening and closing controllable plasma photonic crystal structure according to claim 1, characterized in that: The background medium is selected from air or an insulating medium.

9. The dual-bandgap opening and closing controllable plasma photonic crystal structure according to claim 8, characterized in that: The relative dielectric constant of the insulating medium is 1-2.

10. The dual-bandgap opening and closing controllable plasma photonic crystal structure according to claim 1, characterized in that: The plasma has a density of 0-10×10 11 cm -3 Adjustable range.

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