Multi-band terahertz energy collector with nested octagonal structure

Abstract

The invention discloses a multi-band terahertz energy collector of a nested octagonal structure, and belongs to the technical field of terahertz regulation and control. Each resonant cavity comprises a reflection bottom plate, a middle dielectric layer, a metasurface and a top dielectric layer which are sequentially arranged from bottom to top; the metasurface is laid on the middle dielectric layer; a nested octagonal structure is arranged on the super-structure surface, and the nested octagonal structure comprises an outer octagonal ring, an inner octagonal ring and a pattern based on a regular polygon structure, wherein the outer octagonal ring and the inner octagonal ring have the same centroid; the inner octagonal ring is sleeved outside the geometric pattern; the inner octagonal ring is sleeved with the outer octagonal ring, and the eight edges of the outer octagonal ring are parallel to the eight edges of the inner octagonal ring respectively. According to the invention, selective absorption of terahertz energy of any multiple frequency bands in the frequency range of 0-8THz can be realized, and the bandwidth of each absorption frequency band is increased, so that the energy absorption efficiency is improved and the loss is reduced.

Description

Technical Field

[0001] The present invention belongs to the field of terahertz regulation technology, and in particular relates to a multi-band terahertz energy collector with a nested octagonal structure. Background Art

[0002] Terahertz waves are electromagnetic waves with frequencies between approximately 0.1 and 10 THz. With the continuous development of emerging terahertz science and technology, their applications have expanded to nondestructive testing, security inspections, radar detection, medical imaging, broadband communications, and more. The richness of frequency information contained in the terahertz band and its unique spectral characteristics make it a significant advantage in accurately detecting small targets. Therefore, developing energy harvesting devices specifically designed for the terahertz band to fully utilize its high-frequency characteristics has become a crucial research task.

[0003] Currently, terahertz energy harvesting devices based on metasurfaces have been developed. These harvesters convert the energy of incident terahertz waves into other energies and dissipate them by stimulating localized surface plasmon resonance on the surface of the material, thereby achieving selective absorption of specific terahertz frequency bands.

[0004] Metasurfaces are a new type of artificially designed material. As a two-dimensional form of metamaterial, metasurfaces are composed of a large number of periodically arranged subwavelength-scale metastructured unit structures. The above-mentioned metastructured unit structures can precisely control the propagation characteristics of electromagnetic waves such as reflection, refraction, polarization and phase. The emergence of metasurfaces provides unprecedented flexibility and precision for the manipulation of electromagnetic waves (i.e., the absorption of electromagnetic wave energy), giving it broad application prospects in sensing, non-destructive testing and antennas. With the advancement of materials science and micro-nano manufacturing technology, the design and manufacture of metasurfaces have become more feasible, providing possibilities for the practical application of metasurfaces.

[0005] Despite significant advances in existing metasurface technology, terahertz energy harvesters still face challenges in practical applications. Multi-band terahertz energy harvesters can increase selectivity, facilitating precise selection of terahertz waves within the desired frequency band. However, existing technologies currently only absorb a limited range of terahertz waves, and the bandwidth of each absorbable frequency band is relatively narrow, directly impacting energy absorption efficiency, loss, and utilization.

[0006] In summary, there is an urgent need to carry out research on energy harvesting devices that can achieve multi-band terahertz absorption to meet the needs of energy harvesting, non-destructive testing, and super-resolution imaging. Summary of the Invention

[0007] In view of this, the present invention provides a multi-band terahertz energy harvester with a nested octagonal structure, which can achieve selective absorption of terahertz energy in any multiple frequency bands in the frequency range of 0-8THz, while increasing the bandwidth of each absorption band, thereby improving energy absorption efficiency and reducing loss.

[0008] The present invention is achieved through the following technical solutions:

[0009] A multi-band terahertz energy harvester with a nested octagonal structure, comprising: a plurality of periodically arranged resonant cavities;

[0010] Each of the resonant cavities comprises a reflective bottom plate, an intermediate dielectric layer, a metasurface, and a top dielectric layer, which are arranged in sequence from bottom to top;

[0011] The metasurface is laid on the intermediate dielectric layer; a nested octagonal structure is provided on the metasurface, the nested octagonal structure comprising: an outer octagonal ring with the same centroid, an inner octagonal ring, and a pattern based on a regular polygon structure;

[0012] The inner octagonal ring is set outside the geometric pattern;

[0013] The outer octagonal ring is sleeved outside the inner octagonal ring, and the eight sides of the outer octagonal ring are respectively parallel to the eight sides of the inner octagonal ring.

[0014] Furthermore, the outer peripheral surfaces of the four oblique sides B of the outer octagonal ring are in a step-like structure.

[0015] Furthermore, the inner circumference of the four oblique sides A of the inner octagonal ring has a step-like structure.

[0016] Furthermore, the pattern in each resonant cavity is any one of a regular octagon, a hexagram, and an octagonal star.

[0017] Furthermore, when the pattern is a hexagram, each vertex angle is 60°.

[0018] Furthermore, when the pattern is an octagonal star, each vertex angle is 90°.

[0019] Furthermore, it includes: resonant cavities of two or more structural forms;

[0020] The patterns of the resonant cavities of different structural forms are different.

[0021] Furthermore, the collection frequency band and the bandwidth of the corresponding frequency band can be adjusted by changing the array form, changing the pattern, or changing the surface resistance of the metasurface.

[0022] Beneficial effects:

[0023] (1) A multi-band terahertz energy collector with a nested octagonal structure, wherein a nested octagonal structure is provided on a metasurface, wherein the nested octagonal structure comprises a geometric pattern with the same centroid, an inner octagonal ring and an outer octagonal ring. The metasurface structure is simple and easy to prepare, so that the collector can absorb multi-band terahertz energy in the frequency range of 0-8THz and increase the bandwidth of each corresponding frequency band, thereby improving the energy absorption efficiency, loss and utilization, so that the collector can be applied to energy collection, non-destructive testing and super-resolution imaging and other fields; the top dielectric layer can further improve the absorption efficiency of terahertz energy; by nesting the octagonal structure, while achieving the selective absorption of terahertz energy in any multiple frequency bands in the frequency range of 0-8THz, the bandwidth of each absorption frequency band is also increased, thereby improving the energy absorption efficiency and reducing the loss.

[0024] (2) A multi-band terahertz energy collector with a nested octagonal structure, the pattern of which is any one of a regular octagon, a hexagram, and an octagonal star, so that the collector can ensure the absorption of terahertz energy in any three or more frequency bands within the frequency range of 0-8THz.

[0025] (3) A multi-band terahertz energy collector with a nested octagonal structure, which is any one of a combination of resonant cavities with regular octagonal and hexagram patterns, a combination of resonant cavities with regular octagonal and octagonal patterns, and a combination of resonant cavities with hexagram and octagonal patterns. By mixing and using two resonant cavities with different patterns, the number of collected frequency bands can be further increased, and the resonant absorption of terahertz waves can be further enhanced.

[0026] (4) A multi-band terahertz energy harvester with a nested octagonal structure can adjust the collection frequency band and the bandwidth of the corresponding frequency band by changing the array form, changing the pattern, or changing the surface resistance of the metasurface, thereby realizing the research of multi-band terahertz absorption energy harvesting devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the three-dimensional structure of the resonant cavity of the present invention (taking a regular octagonal structure as an example);

[0028] Figure 2 2 is a front view of the resonant cavity of the present invention (the pattern is a regular octagonal structure);

[0029] Figure 3 A periodic array diagram of the metasurface of the present invention (the pattern is a regular octagonal structure);

[0030] Figure 4 This is a graph showing the electromagnetic wave resonant absorption characteristics of the present invention in the terahertz band (the surface resistance of the metasurface is 100Ω / sq, and the pattern is a regular octagonal structure);

[0031] Figure 5 This is a graph showing the electromagnetic wave resonant absorption characteristics of the present invention in the terahertz band (the surface resistance of the metasurface is 80Ω / sq, and the pattern is a regular octagonal structure);

[0032] Figure 6 This is a front view of the resonant cavity of the present invention (the pattern is a hexagram structure);

[0033] Figure 7 The periodic array diagram of the metasurface of the present invention (the pattern is a hexagram structure);

[0034] Figure 8 This is a curve diagram of the electromagnetic wave resonance absorption characteristics of the present invention in the terahertz band (the pattern is a hexagram structure);

[0035] Figure 9 This is a front view of the resonant cavity of the present invention (the pattern is an octagonal star structure);

[0036] Figure 10 The periodic array diagram of the metasurface of the present invention (the pattern is an octagonal star structure);

[0037] Figure 11 This is a curve diagram of the electromagnetic wave resonance absorption characteristics of the present invention in the terahertz band (the pattern is an octagonal star structure);

[0038] Figure 12 The periodic array diagram of the metasurface of the present invention (a mixture of a resonant cavity with a hexagram structure and a resonant cavity with a regular octagon structure);

[0039] Figure 13 This is a curve diagram of the electromagnetic wave resonance absorption characteristics of the present invention in the terahertz band (a mixture of a resonant cavity with a hexagram-shaped structure and a resonant cavity with a regular octagonal structure);

[0040] Among them, 1-reflective base, 2-middle dielectric layer, 3-metasurface, 4-top dielectric layer, 5-outer octagonal ring, 6-inner octagonal ring, 7-pattern. DETAILED DESCRIPTION

[0041] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0042] Example 1:

[0043] This embodiment provides a multi-band terahertz energy harvester with a nested octagonal structure. The cavities are periodically arranged in an m×n array, where m represents the number of rows and n represents the number of columns. Both m and n are arbitrary natural numbers. Each pair of adjacent cavities is aligned with each other.

[0044] like Figure 1 As shown, each resonant cavity includes: a reflective bottom plate 1, an intermediate dielectric layer 2, a metasurface 3 and a top dielectric layer 4.

[0045] In actual use, the reflective base plate 1 is not limited to be located at the bottom.

[0046] The reflective bottom plate 1 is a conductive film with a surface resistance of 13Ω / sq.

[0047] The intermediate dielectric layer 2 is arranged above the reflective base plate 1 and is a FEP film (ie, a fluorinated ethylene propylene copolymer film) having a dielectric constant of 2.1.

[0048] The metasurface 3 is laid on the intermediate dielectric layer 2. A nested octagonal structure is provided on the metasurface 3, located in the middle of the intermediate dielectric layer 2. The nested octagonal structure comprises an outer octagonal ring 5, an inner octagonal ring 6, and a pattern 7 based on a regular polygon structure, all with the same centroid.

[0049] In this embodiment, the pattern 7 is preferably one of a regular octagon, a hexagram, and an octagonal star.

[0050] The inner octagonal ring 6 is sleeved over the pattern 7, with the two having the same centroid. The inner octagonal ring 6 has four sides that are parallel to the four sides of the intermediate dielectric layer 2. These four sides are called regular sides A, and the remaining sides are called hypotenuses A. The inner circumference of the four hypotenuses A of the inner octagonal ring 6 is stepped.

[0051] The outer octagonal ring 5 is sleeved over the inner octagonal ring 6, with the two having the same centroid. The eight sides of the outer octagonal ring 5 are parallel to the eight sides of the inner octagonal ring 6. The four hypotenuses of the outer octagonal ring 5 (corresponding to the four hypotenuses A of the inner octagonal ring 6) are called hypotenuses B, and the sides other than the four hypotenuses B are called straight sides B. The outer circumference of the four hypotenuses B of the outer octagonal ring 5 is stepped.

[0052] The top dielectric layer 4 is disposed above the metasurface 3 and is an FEP film with a dielectric constant of 2.1.

[0053] In this embodiment, the pattern of the metasurface 3 is formed by laser etching. Specifically, the metasurface 3 comprises a base material and a resistive dielectric layer (e.g., indium tin oxide (ITO)) disposed on the base material. The resistive dielectric layer is burned using laser etching to remove excess structural areas (i.e., the areas not hatched in the accompanying drawings), leaving behind a nested octagonal structure.

[0054] By changing the array form, changing the pattern 7, changing the surface resistance of the metasurface 3, or changing the structural parameters of the metasurface 3 (such as the dimensions of the outer and inner circumferences of the right side B and the oblique side B of the outer octagonal ring 5, and the dimensions of the outer and inner circumferences of the right side A and the right side B of the inner octagonal ring 6, etc.), the collection frequency band and the response frequency band bandwidth can be adjusted.

[0055] As an example, the terahertz energy harvester includes resonant cavities of two or more structural forms, each having a different pattern 7. These may include a combination of a resonant cavity with a regular octagonal pattern 7 and a resonant cavity with a hexagram pattern 7, a combination of a resonant cavity with a regular octagonal pattern 7 and a resonant cavity with an octagonal pattern 7, or a combination of a resonant cavity with a hexagram pattern 7 and a resonant cavity with an octagonal pattern 7. By combining two resonant cavities with different patterns 7, the number of collected frequency bands can be further increased, further enhancing the resonant absorption of terahertz waves.

[0056] Example 2:

[0057] Based on Example 1, Figure 3 As shown, this embodiment provides a multi-band terahertz energy harvester with a nested octagonal structure, which is used to absorb multiple terahertz bands in the frequency range of 0-8THz.

[0058] In this embodiment, the thickness of the reflective bottom plate 1 of each resonant cavity is 2 μm; the thickness of the intermediate dielectric layer 2 and the top dielectric layer 4 are both 26 μm; and the thickness of the metasurface 3 is 2 μm.

[0059] In this embodiment, the patterns 7 of each metasurface 3 are regular octagons.

[0060] The nested octagonal structure of each metasurface 3 ( Figure 2 ) are as follows:

[0061] The periodic array period of the metasurface 3 of the resonant cavity (i.e., the side length of one metasurface 3) is x = 200 μm;

[0062] Other structural parameters: L1 = 150 μm, L2 = 96 μm, L3 = 9 μm, L4 = 10.5 μm, L5 = 9 μm, L6 = 53.4 μm, L7 = 46 μm, L8 = 36 μm, L10 = 9 μm, L11 = 10.5 μm, L9 = 60 μm;

[0063] in,

[0064] L1 is the distance between the outer circumferences of two opposite positive sides B of the outer octagonal ring 5;

[0065] L2 is the length of the outer circumference of each positive side B of the outer octagonal ring 5;

[0066] L3 is the width of each step surface of the step-like structure of each oblique side B of the outer octagonal ring 5;

[0067] L4 is the distance between the outer circumference and the inner circumference of each positive side B of the outer octagonal ring 5;

[0068] L5 is the distance between the inner circumference of the outer octagonal ring 5 and the outer circumference of the inner octagonal ring 6;

[0069] L6 is the length of the inner circumference of each positive side B of the outer octagonal ring 5;

[0070] L7 is the length of the outer circumference of each positive side A of the inner octagonal ring 6;

[0071] L8 is the length of the inner circumference of each positive side A of the inner octagonal ring 6;

[0072] L9 is the distance between two opposite sides of the regular octagon when pattern 7 is a regular octagon;

[0073] L10 is the width of each step surface of the step-like structure of each oblique side A of the inner octagonal ring 6;

[0074] L11 is the distance between the outer circumference and the inner circumference of each positive side A of the inner octagonal ring 6 .

[0075] When the surface resistance of the metasurface 3 is 100Ω / sq, Figure 4 As shown, the absorber in this embodiment can absorb three terahertz wave frequency bands of 0.76-2.03THz, 4.66-5.39THz and 6.09-6.91THz, and the absorption bandwidth of the total terahertz frequency band is 2.82THz, that is, it can realize the collection of multi-band terahertz energy, increase the bandwidth of the absorbable frequency band, and enhance the resonant absorption of terahertz waves.

[0076] When the surface resistance of the metasurface 3 is 80Ω / sq, Figure 5 As shown, the absorber in this embodiment can absorb electromagnetic waves in four terahertz frequency bands: 0.80-1.41 THz, 1.66-2.13 THz, 4.69-5.38 THz, and 6.10-6.91 THz, and the total terahertz wave bandwidth is 2.58 THz.

[0077] Example 3:

[0078] Based on Example 1, Figure 7 It is shown that this embodiment provides a multi-band terahertz energy harvester with a nested octagonal structure, which is used to absorb multiple terahertz bands in the frequency range of 0-8THz.

[0079] In this embodiment, the thickness of the reflective bottom plate 1 of each resonant cavity is 2 μm; the thickness of the intermediate dielectric layer 2 and the top dielectric layer 4 are both 26 μm; and the thickness of the metasurface 3 is 2 μm.

[0080] In this embodiment, the pattern 7 of each metasurface is in the shape of a hexagram, and each vertex angle of the hexagram is 60°, that is, the shape of the hexagram is formed by overlapping two equilateral triangles with coincident centers.

[0081] The nested octagonal structure of each metasurface 3 ( Figure 6 ) are as follows:

[0082] The periodic array period of the metasurface of the resonant cavity (i.e., the side length of one metasurface 3) is x = 200 μm;

[0083] Other structural parameters: L1 = 150 μm, L2 = 96 μm, L3 = 9 μm, L4 = 10.5 μm, L5 = 9 μm, L6 = 53.4 μm, L7 = 46 μm, L8 = 96 μm, L10 = 9 μm, L11 = 10.5 μm, D1 = 69.3 μm;

[0084] in,

[0085] L1 is the distance between the outer circumferences of two opposite positive sides B of the outer octagonal ring 5;

[0086] L2 is the length of the outer circumference of each positive side B of the outer octagonal ring 5;

[0087] L3 is the width of each step surface of the step-like structure of each oblique side B of the outer octagonal ring 5;

[0088] L4 is the distance between the outer circumference and the inner circumference of each positive side B of the outer octagonal ring 5;

[0089] L5 is the distance between the inner circumference of the outer octagonal ring 5 and the outer circumference of the inner octagonal ring 6;

[0090] L6 is the length of the inner circumference of each positive side B of the outer octagonal ring 5;

[0091] L7 is the length of the outer circumference of each positive side A of the inner octagonal ring 6;

[0092] L8 is the length of the inner circumference of each positive side A of the inner octagonal ring 6;

[0093] L10 is the width of each step surface of the step-like structure of each oblique side A of the inner octagonal ring 6;

[0094] L11 is the distance between the outer circumference and the inner circumference of each positive side A of the inner octagonal ring 6;

[0095] When the pattern 7 is in the shape of a hexagram, D1 is the side length of each equilateral triangle forming the hexagram.

[0096] When the surface resistance of the metasurface is 100Ω / sq, Figure 8 As shown, the absorber in this embodiment can absorb three terahertz wave frequency bands of 0.74-1.96THz, 4.63-5.38THz and 6.15-6.91THz, and the absorption bandwidth of the total terahertz frequency band is 2.73THz, that is, it can realize the collection of multi-band terahertz energy, increase the bandwidth of the absorbable frequency band, and enhance the resonant absorption of terahertz waves.

[0097] Example 4:

[0098] Based on Example 1, Figure 10 As shown, this embodiment provides a multi-band terahertz energy harvester with a nested octagonal structure, which is used to absorb multiple terahertz bands in the frequency range of 0-8THz.

[0099] In this embodiment, the thickness of the reflective bottom plate 1 of each resonant cavity is 2 μm; the thickness of the intermediate dielectric layer 2 and the top dielectric layer 4 are both 26 μm; and the thickness of the metasurface 3 is 2 μm.

[0100] In this embodiment, the pattern 7 of each metasurface 3 is an octagonal star, and each vertex angle of the octagonal star is 60°, that is, the shape of the octagonal star is formed by overlapping two squares with overlapping centers.

[0101] The nested octagonal structure of each metasurface ( Figure 9 ) are as follows:

[0102] The periodic array period of the metasurface of the resonant cavity (i.e., the side length of one metasurface 3) is x = 200 μm;

[0103] Other structural parameters: L1 = 150 μm, L2 = 96 μm, L3 = 9 μm, L4 = 10.5 μm, L5 = 9 μm, L6 = 53.4 μm, L7 = 46 μm, L8 = 96 μm, L10 = 9 μm, L11 = 10.5 μm, D2 = 40 μm;

[0104] in,

[0105] L1 is the distance between the outer circumferences of two opposite positive sides B of the outer octagonal ring 5;

[0106] L2 is the length of the outer circumference of each positive side B of the outer octagonal ring 5;

[0107] L3 is the width of each step surface of the step-like structure of each oblique side B of the outer octagonal ring 5;

[0108] L4 is the distance between the outer circumference and the inner circumference of each positive side B of the outer octagonal ring 5;

[0109] L5 is the distance between the inner circumference of the outer octagonal ring 5 and the outer circumference of the inner octagonal ring 6;

[0110] L6 is the length of the inner circumference of each positive side B of the outer octagonal ring 5;

[0111] L7 is the length of the outer circumference of each positive side A of the inner octagonal ring 6;

[0112] L8 is the length of the inner circumference of each positive side A of the inner octagonal ring 6;

[0113] L10 is the width of each step surface of the step-like structure of each oblique side A of the inner octagonal ring 6;

[0114] L11 is the distance between the outer circumference and the inner circumference of each positive side A of the inner octagonal ring 6;

[0115] D2 is the side length of each square forming the octagonal star when the pattern 7 is an octagonal star.

[0116] When the surface resistance of the metasurface is 100Ω / sq, Figure 11 As shown, the absorber in this embodiment can absorb four terahertz wave frequency bands of 0.85-1.38THz, 1.77-1.98THz, 4.63-5.39THz and 6.06-6.89THz, and the absorption bandwidth of the total terahertz frequency band is 2.33THz, that is, it can realize the collection of multi-band terahertz energy, increase the bandwidth of the absorbable frequency band, and enhance the resonant absorption of terahertz waves.

[0117] Example 5:

[0118] like Figure 12 As shown, this embodiment provides a multi-band terahertz energy collector with a nested octagonal structure. Based on Example 2, this embodiment further combines the technical solution in Example 3, that is, the collector in this embodiment simultaneously adopts the resonant cavity with a regular octagon in pattern 7 in Example 2 and the resonant cavity with a hexagram in pattern 7 in Example 3.

[0119] When the two resonant cavities are arranged in a two-dimensional staggered manner and the surface resistance of the metasurface 3 of the two resonant cavities is 100Ω / sq, Figure 13As shown in the figure, the absorber can absorb four terahertz wave frequency bands: 0.76-1.44THz, 1.66-2.03THz, 4.66-5.38THz and 6.13-6.92THz, and the absorption bandwidth of the total terahertz frequency band is 2.56THz, that is, it can realize the collection of multi-band terahertz energy, increase the bandwidth of the absorbable frequency band, and enhance the resonant absorption of terahertz waves.

[0120] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A multi-band terahertz energy harvester with a nested octagonal structure, characterized in that: include: Several periodically arranged resonant cavities; Each resonant cavity comprises a reflective bottom plate (1), an intermediate dielectric layer (2), a metasurface (3), and a top dielectric layer (4) which are arranged in sequence from bottom to top; The metasurface (3) is laid on the intermediate medium layer (2); a nested octagonal structure is provided on the metasurface (3), and the nested octagonal structure includes: an outer octagonal ring (5) having the same centroid, an inner octagonal ring (6), and a pattern (7) based on a regular polygon structure; The inner octagonal ring (6) is sleeved on the outside of the geometric pattern (7); The outer octagonal ring (5) is sleeved outside the inner octagonal ring (6), and the eight sides of the outer octagonal ring (5) are respectively parallel to the eight sides of the inner octagonal ring (6).

2. The multi-band terahertz energy harvester with a nested octagonal structure as claimed in claim 1, characterized in that: The outer peripheral surfaces of the four oblique sides B of the outer octagonal ring (5) are in a step-like structure.

3. The multi-band terahertz energy harvester with a nested octagonal structure as claimed in claim 1, characterized in that: The inner circumference of the four oblique sides A of the inner octagonal ring (6) is in a step-like structure.

4. The multi-band terahertz energy harvester with a nested octagonal structure as claimed in claim 1, characterized in that: The pattern (7) in each resonant cavity is any one of a regular octagon, a hexagram, and an octagonal star.

5. The multi-band terahertz energy harvester with a nested octagonal structure as claimed in claim 4, characterized in that: When the pattern (7) is in the shape of a hexagram, each vertex angle is 60°.

6. The multi-band terahertz energy harvester with a nested octagonal structure as claimed in claim 4, characterized in that: When the pattern (7) is an octagonal star, each vertex angle is 90°.

7. The multi-band terahertz energy harvester with a nested octagonal structure as claimed in claim 1, characterized in that: include: Resonant cavities with two or more structural forms; The patterns (7) of the resonant cavities of different structural forms are different.

8. A multi-band terahertz energy harvester with a nested octagonal structure according to any one of claims 1 to 7, characterized in that: The collection frequency band and the bandwidth of the corresponding frequency band can be adjusted by changing the array form or changing the pattern (7) or changing the surface resistance of the metasurface (3).

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