A frequency-selective dual-band terahertz absorber

Abstract

This invention discloses a highly frequency-selective dual-band terahertz absorber, comprising several square periodic units. Each square periodic unit includes a metal layer, an intermediate dielectric layer, and a metasurface structure connected sequentially from top to bottom. The metasurface structure includes edge square rings, a central square ring located in the middle of the four edge square rings and intersecting with all four edge square rings, and a central square ring located inside the central square ring and intersecting with all four edge square rings. Through a unique metasurface structure design, this invention achieves highly frequency-selective dual-band absorption in the 0-1.2THz range at 0.51THz and 1.01THz when terahertz is incident. The absorbance at 0.51THz is 83%, with a Q value of 225; the absorbance at 1.01THz is 92%, with a Q value of 165, exhibiting high quality factor dual-band absorption. This solves the problem of current narrowband terahertz metasurface absorbers struggling to balance quality factor and multi-band performance, achieving high quality factor frequency absorption in both terahertz bands.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic wave absorption technology, and in particular to a dual-band terahertz absorber with strong frequency selectivity. Background Technology

[0002] Terahertz (THz) waves typically refer to electromagnetic waves with frequencies between 0.1 and 10 THz. They possess many unique properties, such as low energy, strong penetrability, and fingerprint-like characteristics, making them highly promising for applications in security inspection, biomedicine, and communications. However, the weak interaction between terahertz waves and natural materials hinders the development of terahertz technology. Metasurfaces, with their advantages of miniaturization and ease of integration, are considered a superior solution for terahertz technology. Terahertz absorbers, as one of the key components in terahertz systems, are widely used in imaging, biosensing, and electromagnetic stealth. In biosensing, communication sensing, and photoelectric detection, narrowband terahertz absorbers have significant application value due to their high absorption rate and narrow bandwidth. Therefore, researchers have designed various narrowband absorbers using metasurfaces. In 2023, Wuhan University designed a narrowband perfect metasurface absorber based on a micro-ring structure GaAs array. The proposed perfect absorber achieved 99.9% absorbance and a Q factor of approximately 460.08 at 2.213 THz. In 2024, Xi'an University of Technology designed a terahertz metasurface narrowband absorber based on single-walled carbon nanotube thin films, consisting of square and I-shaped slits. This absorber exhibited four distinct resonant absorption peaks at 0.65, 0.85, 1.16, and 1.31 THz, achieving a perfect absorption rate of up to 90%. This research demonstrates that achieving strong frequency-selective absorption across multiple frequency bands presents significant challenges. Summary of the Invention

[0003] This invention provides a dual-band terahertz absorber with strong frequency selectivity, which solves the problem that current terahertz metasurface narrowband absorbers cannot simultaneously achieve both high quality factor and multiple frequency bands, and achieves high quality factor frequency absorption in both terahertz bands.

[0004] To achieve the above objectives, the present invention provides the following solution:

[0005] A highly frequency-selective dual-band terahertz absorber includes several square periodic units arranged in a periodic manner. Each square periodic unit includes a metal layer, an intermediate dielectric layer, and a metasurface structure connected sequentially from top to bottom. The metasurface structure includes four edge square rings arranged in an array, a middle square ring disposed in the middle of the four edge square rings and intersecting with all four edge square rings, and a central square ring disposed inside the middle square ring and intersecting with all four edge square rings.

[0006] Preferably, the width of the edge square ring and the width of the middle square ring are the same, both being 6μm.

[0007] Preferably, the outer side length of the edge square ring is 48 μm, and the distance between the outer sides of adjacent edge square rings is 4 μm.

[0008] Preferably, the distance between the middle square ring and the edge square ring is 6 μm.

[0009] Preferably, the distance between the central square ring and the middle square ring is 12 μm.

[0010] Preferably, the outer side length of the central square ring is 40 μm and the inner side length is 16 μm.

[0011] Preferably, the metal layer is made of gold, has a thickness of 0.3 μm, and an electrical conductivity of 4.56 × 10⁻⁶. 7 S / m.

[0012] Preferably, the intermediate dielectric layer is made of polytetrafluoroethylene, has a thickness of 200 μm, and a dielectric constant of 2.55.

[0013] Preferably, the metasurface unit material is gold, with a thickness of 0.2 μm and an electrical conductivity of 4.56 × 10⁻⁶. 7 S / m.

[0014] The present invention achieves the following technical effects compared to the prior art:

[0015] This invention, through a unique metasurface structure design, enables the absorber to achieve strong frequency selectivity in both 0.51THz and 1.01THz bands when terahertz is incident. The absorbance at 0.51THz is 83% with a Q value of 225, and at 1.01THz it is 92% with a Q value of 165, exhibiting high quality factor dual-band absorption. This solves the problem of current terahertz metasurface narrowband absorbers struggling to balance quality factor and multi-band performance, achieving high quality factor frequency absorption in both terahertz bands. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the square periodic unit structure of the present invention;

[0018] Figure 2This is a schematic diagram of the parameters of the square periodic unit of the present invention;

[0019] Figure 3 The graph shows the absorption rate of the highly frequency-selective dual-band terahertz absorber proposed in this invention as a function of frequency.

[0020] Among them, 1. Metal layer; 2. Intermediate dielectric layer; 3. Metasurface structure; 4. Edge square ring; 5. Middle square ring; 6. Center square ring; L1, outer side length of the edge square ring; L2, outer side distance between adjacent edge square rings; L3, width of the edge square ring or middle square ring; L4, distance between the middle square ring and the edge square ring; L5, distance between the center square ring and the middle square ring; L6, outer side length of the center square ring; L7, inner side length of the center square ring. Detailed Implementation

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] This invention provides a dual-band terahertz absorber with strong frequency selectivity, which solves the problem that current terahertz metasurface narrowband absorbers cannot simultaneously achieve both high quality factor and multiple frequency bands, and achieves high quality factor frequency absorption in both terahertz bands.

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] refer to Figures 1 to 3A highly frequency-selective dual-band terahertz absorber is disclosed, comprising a plurality of periodically arranged square periodic units. Each square periodic unit includes a metal layer, an intermediate dielectric layer, and a metasurface structure connected sequentially from top to bottom. The metasurface structure includes four edge square rings arranged in an array, a central square ring disposed in the middle of the four edge square rings and intersecting with all four edge square rings, and a central square ring disposed inside the central square ring and intersecting with all four edge square rings. Through a unique metasurface structure design, this invention achieves highly frequency-selective dual-band absorption in the 0-1.2THz range at 0.51THz and 1.01THz when terahertz is incident. The absorbance at 0.51THz is 83%, with a Q value of 225; the absorbance at 1.01THz is 92%, with a Q value of 165, exhibiting high quality factor dual-band absorption. This solves the problem of current narrowband terahertz metasurface absorbers struggling to balance quality factor and multi-band performance, achieving high quality factor frequency absorption in both terahertz bands.

[0025] Furthermore, the edge square ring and the middle square ring have the same width, both being 6μm.

[0026] Furthermore, the outer side length of the edge square ring is 48 μm, and the distance between the outer sides of adjacent edge square rings is 4 μm.

[0027] Furthermore, the spacing between the middle square ring and the edge square ring is 6 μm.

[0028] Furthermore, the distance between the central square ring and the middle square ring is 12 μm.

[0029] Furthermore, the outer side length of the central square ring is 40 μm, and the inner side length is 16 μm.

[0030] Furthermore, the metal layer material is gold, with a thickness of 0.3 μm and an electrical conductivity of 4.56 × 10⁻⁶. 7 S / m.

[0031] Furthermore, the intermediate dielectric layer material is polytetrafluoroethylene, with a thickness of 200 μm and a dielectric constant of 2.55.

[0032] Furthermore, the metasurface structure material is gold, with a thickness of 0.2 μm and an electrical conductivity of 4.56 × 10⁻⁶. 7 S / m.

[0033] refer to Figure 3When terahertz is incident, the absorber can achieve strong frequency selectivity in the dual-band absorption of 0.51THz and 1.01THz in the range of 0-1.2THz. The absorbance of the absorber is 83% and the Q value is 225 at 0.51THz; the absorbance of the absorber is 92% and the Q value is 165 at 1.01THz, which shows a high quality factor dual-band absorption.

[0034] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A highly frequency-selective dual-band terahertz absorber, characterized in that, It includes several square periodic units arranged in a periodic manner. Each square periodic unit includes a metal layer, an intermediate dielectric layer, and a metasurface structure connected sequentially from top to bottom. The metasurface structure includes four edge square rings arranged in an array, a middle square ring disposed in the middle of the four edge square rings and intersecting with the four edge square rings, and a central square ring disposed inside the middle square ring and intersecting with the four edge square rings.

2. The highly frequency-selective dual-band terahertz absorber according to claim 1, characterized in that, The edge square ring and the middle square ring have the same width, both being 6μm.

3. The highly frequency-selective dual-band terahertz absorber according to claim 2, characterized in that, The outer side length of the edge square ring is 48 μm, and the distance between the outer sides of adjacent edge square rings is 4 μm.

4. The highly frequency-selective dual-band terahertz absorber according to claim 3, characterized in that, The distance between the middle square ring and the edge square ring is 6 μm.

5. The highly frequency-selective dual-band terahertz absorber according to claim 4, characterized in that, The distance between the central square ring and the middle square ring is 12 μm.

6. The highly frequency-selective dual-band terahertz absorber according to claim 5, characterized in that, The outer side length of the central square ring is 40 μm, and the inner side length is 16 μm.

7. The highly frequency-selective dual-band terahertz absorber according to claim 1, characterized in that, The metal layer is made of gold, has a thickness of 0.3 μm, and an electrical conductivity of 4.56 × 10⁻⁶. 7 S / m.

8. The highly frequency-selective dual-band terahertz absorber according to claim 1, characterized in that, The intermediate dielectric layer is made of polytetrafluoroethylene, has a thickness of 200 μm, and a dielectric constant of 2.

55.

9. The highly frequency-selective dual-band terahertz absorber according to claim 1, characterized in that, The metasurface structure material is gold, with a thickness of 0.2 μm and an electrical conductivity of 4.56 × 10⁻⁶. 7 S / m.

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