Single-layered T-shaped band terahertz filter metamaterial

Abstract

The application provides a single-layer three-passband terahertz filter metamaterial, which comprises a metamaterial sheet layer and a plurality of artificial microstructures arranged in an array in the metamaterial sheet layer, each artificial microstructure and a corresponding part of the metamaterial sheet layer are defined as a metamaterial unit together, each metamaterial sheet layer can be regarded as being arranged by the array of the metamaterial units, when electromagnetic waves enter the metamaterial, the artificial microstructures are coupled to enable the metamaterial to reflect electromagnetic waves of other frequencies by reflecting terahertz wave bands of three specific frequency ranges, namely, the metamaterial is equivalent to a three-passband terahertz filter, and the application demand of different terahertz frequency bands can be met; in addition, compared with traditional metal-dielectric and metal-dielectric-metal filter metamaterials, the metamaterial composed of only a single metamaterial sheet layer has the advantages of light weight, low price and easy processing, the metamaterial can greatly reduce the processing difficulty of designing and processing terahertz devices, and is beneficial to the development of terahertz technology.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic communication, and in particular to a single-layer three-band terahertz filtering metamaterial. Background Technology

[0002] Metamaterials refer to artificial composite structures or composite materials that possess extraordinary physical properties not found in natural materials. By altering the artificial microstructure within the material, desired physical properties can be obtained, breaking through the limitations of certain apparent natural laws, thereby acquiring extraordinary materials with properties exceeding those inherent in nature.

[0003] In recent years, with the increasing scarcity of spectrum resources, the research and application of terahertz (THz) devices in fields such as chemical and biological sensing, imaging, security, and communications have received widespread attention. Bandpass filters are an important device in communications, and in the terahertz band, most researchers focus on the design and fabrication of single-passband bandpass filters. However, astronomical applications require filtering materials with multiple passbands. Current multi-band filtering materials are mainly fabricated on dielectric substrates, which become very fragile when the thickness of these substrates drops below 150 μm, and are also prone to significant insertion losses. Furthermore, the fabrication process of these metal-dielectric materials is relatively complex compared to metallic dielectrics or single-layer metal structures.

[0004] In 2015, Qi et al. (L.Qi,C.Li,G.Fang,S.Li,Single-layer dual-bandterahertz filter with weak coupling between two neighboring cross slots,Chinese Physics B.24(2015)107802.) designed and fabricated a THz single-layer dual-band filter material. They designed a periodic microstructure pattern within a metal layer and used the weak connection coupling between adjacent cross-coupled slots to achieve dual-band filtering. This method is not only simple in design principle and manufacturing, but also low in cost.

[0005] The aforementioned single-metal layer filter material has only two frequency bands. In practical applications of THz devices, due to the complexity of the spectrum, there is an urgent need for materials that can filter signals in multiple THz frequency bands. Summary of the Invention

[0006] To address the aforementioned problems in related technologies, this invention proposes a single-layer three-band terahertz filtering metamaterial that can select frequencies for three bands of electromagnetic waves in the THz band. Furthermore, it is fabricated using a single metal layer, making the process simple and low-cost.

[0007] A single-layer three-way terahertz filtering metamaterial, which includes a metal layer and a plurality of artificial microstructure units formed by punching holes in the metal layer, and the artificial microstructure unit has at least one artificial microstructure.

[0008] Further, the metal layer includes molybdenum or copper.

[0009] Further, the punching method includes laser punching or etching.

[0010] Further, there are rectangular grooves in the upper and lower parts of each side of the artificial microstructure unit, so that a "cross" shaped groove can be formed between every 2×2 adjacent artificial microstructure units.

[0011] Further, the artificial microstructure unit further includes a multi-cross groove.

[0012] Further, the multi-cross groove is formed by the partial intersection of 2n (n is a positive integer greater than 1) groove parts.

[0013] Further, the 2n grooves are rectangles or deformed rectangles after bending, arcs or deformed arcs after bending.

[0014] Further, among the 2n - 1 longitudinal grooves, 2n - 1 longitudinal grooves do not intersect with each other, and 1 transverse groove intersects with 2n - 1 longitudinal grooves respectively.

[0015] Further, in the 2n - 1 longitudinal grooves, the i-th (i is a positive integer and i < n) groove is mirror symmetric with the (2n - i)-th groove with respect to the n-th groove.

[0016] Further, among the 2n - 1 longitudinal grooves, the widths of the non-mirror symmetric grooves can be the same or different.

[0017] Further, among the 2n - 1 longitudinal grooves, the lengths of the non-mirror symmetric grooves can be partially the same or all different, and at least two or more groove lengths are maintained to form resonators with different resonant frequencies.

[0018] Further, the entire artificial microstructure unit is an axisymmetric figure, symmetric about 1 transverse groove, and symmetric about the n-th longitudinal groove.

[0019] Further, the artificial microstructure units are arranged in an array or periodically.

[0020] The metamaterial provided by the present invention forms resonators with different resonant frequencies by designing multiple grooves on a single metal layer, and artificial microstructures are formed by coupling between the resonators. Thus, when multi-frequency electromagnetic waves pass through the metamaterial, THz signals within three specific frequency ranges can be passed, achieving the purpose of three-band filtering. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the single-layer three-band terahertz filtering metamaterial of Embodiment 1 of the present invention;

[0022] Figure 2 This is a schematic diagram of the artificial microstructure unit that constitutes the single-layer three-band terahertz filter metamaterial in Embodiment 1 of the present invention;

[0023] Figure 3 This is a simulation diagram of the normal incident reflection and transmission spectra of the single-layer three-band terahertz filtering metamaterial in Embodiment 1 of the present invention.

[0024] Figure 4 This is a simulation diagram of the normal incident reflection and transmission spectra of the single-layer three-band terahertz filtering metamaterial in Embodiment 2 of the present invention.

[0025] Figure 5 This is a schematic diagram of the artificial microstructure unit that constitutes the single-layer three-band terahertz filter metamaterial in Embodiment 3 of the present invention;

[0026] Figure 6 This is a schematic diagram of the artificial microstructure unit that constitutes the single-layer three-band terahertz filter metamaterial in Embodiment 4 of the present invention. Detailed Implementation

[0027] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0028] Example 1

[0029] This embodiment provides a single-layer three-band terahertz filtering metamaterial, such as Figure 1 , Figure 2 This is a schematic diagram of the structure of Embodiment 1 of the present invention. The metamaterial includes a metal layer and multiple artificial microstructure units S10 formed by drilling within the metal layer. Each artificial microstructure unit S10 has at least one artificial microstructure. The metal layer is molybdenum, and its electrical conductivity is 1.76 × 10⁻⁶. 7S / m; The artificial microstructure unit S10 is formed by laser drilling to create specific grooves. The artificial microstructure unit S10 is arranged periodically in a rectangular array to form the entire metamaterial, that is, arranged with rows in the x-direction and columns perpendicular to the x-direction. The protruding parts on the four sides of each adjacent artificial microstructure unit S10 are connected to form a whole. The upper and lower parts of each side of the artificial microstructure unit S10 have L-shaped rectangular grooves S11 that are bent at right angles, so that a cross-shaped groove can be formed between every 2×2 adjacent artificial microstructure units. The artificial microstructure unit S10 also includes a multi-cross groove in the middle.

[0030] like Figure 2 As shown, the multiple "+" shaped grooves are formed by the intersection of six rectangular grooves (or bent rectangular grooves). Five of these six rectangular grooves, S12-S16, are arranged longitudinally and do not intersect. One transverse rectangular groove, S17, intersects with each of the five longitudinal rectangular grooves to form multiple interconnected cross-shaped grooves. The pattern formed by the six rectangular grooves is symmetrical about the transverse rectangular groove and about the central rectangular groove S14 among the five longitudinal rectangular grooves. Rectangular grooves S12 and S16 have the same width and length and are symmetrical about the central rectangular groove S14. 14. Symmetry: The width and length of rectangular grooves S13 and S15 are the same and symmetrical about rectangular groove S14. In this embodiment, the widths of rectangular grooves S11, S12, S13, and S14 are the same. Since the resonant frequency generated by the rectangular groove is related to the length of the rectangular groove, multiple experimental measurements are needed in practice to determine the length of the rectangular groove in order to generate multiple different resonant frequencies. In this embodiment, the length ratio of rectangular grooves S11, S12, S13, and S14 is 3:2:6:5. Generally, in order to obtain multiple resonant frequencies, the relationship between the width of the cross structure and the resonant frequency of the "+" shaped unit in the frequency selection surface is as follows:

[0031]

[0032] Where L is the maximum cross width selectable in the simulation, λ and f are the resonant wavelength and resonant frequency, respectively, and c is the speed of light. Since no dielectric material is introduced into the structure, i.e., ε... r =1.

[0033] Therefore, all artificial microstructures formed by coupling of "+" resonance and multiple "+" resonances are within the scope of protection of this invention.

[0034] Simulation diagrams of the normal incident reflection and transmission spectra and reflection spectra of the single-layer three-band terahertz filtering metamaterial in Example 1 are shown below. Figure 3As shown in the figure, the horizontal axis represents the resonant frequency, and the vertical axis represents the transmittance and reflectance. It can be seen from the figure that the transmittance and reflectance of rectangular groove S12 and rectangular groove S11 at a frequency of 0.178THz are -1.13dB and -18.23dB, respectively; at a frequency of 0.303THz, the transmittance and reflectance are -0.4dB and -25.3dB, respectively; and at a frequency of 0.383THz, the transmittance and reflectance are -0.93dB and -19.6dB, respectively.

[0035] In this embodiment, multiple grooves are designed on a single metal layer to form resonators with different resonant frequencies. The artificial microstructure formed by coupling these resonators allows multi-frequency electromagnetic waves to pass through the metamaterial, enabling the transmission of THz signals within three specific frequency ranges, thus achieving three-band filtering. This method is simple in design, easy to fabricate, low in cost, and more readily applicable to THz devices.

[0036] Example 2

[0037] This embodiment provides a single-layer three-band terahertz filtering metamaterial, wherein the metal material used for the metal layer has an electrical conductivity of 1.76 × 10⁻⁶. 7 The molybdenum conductivity (S / m) is 5.71 × 10⁻⁶. 7 Apart from the copper in S / m, the rest is the same as in Example 1.

[0038] Simulation diagrams of the normal incident reflection and transmission spectra of the single-layer three-band terahertz filtering metamaterial in Example 2 are shown below. Figure 4 As shown in the figure, the horizontal axis represents the resonant frequency, and the vertical axis represents the transmittance and reflectance. It can be seen from the figure that the transmittance and reflectance of rectangular grooves S12 and S11 at a frequency of 0.178 THz are -0.66 dB and -22.4 dB, respectively; at a frequency of 0.303 THz, they are -0.23 dB and -27.6 dB, respectively; and at a frequency of 0.383 THz, they are -0.66 dB and -22.4 dB, respectively.

[0039] Figure 5 and Figure 6 The diagrams are schematic representations of the artificial microstructure units in Examples 3 and 4, respectively. In Example 3, as shown... Figure 5 As shown, a fan-shaped microstructure can be used instead of a rectangular microstructure; in Example 4, as... Figure 6 As shown, the number of grooves can be expanded to eight. The specific dimensions of the grooves can be adjusted based on the theoretical calculation of formula (1) combined with simulation results. These embodiments illustrate the structural variation characteristics of a material unit of the metamaterial of this invention.

[0040] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Unless otherwise specified, an element defined by the phrase "comprising..." or "including..." does not exclude the presence of additional elements in the process, method, article, or terminal device that includes said element. Additionally, in this document, "greater than," "less than," "exceeding," etc., are understood to exclude the stated number; "above," "below," "within," etc., are understood to include the stated number.

[0041] Although the above embodiments have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the above descriptions are merely embodiments of the present invention and do not limit the scope of patent protection of the present invention. Any equivalent structural or procedural transformations made using the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

[0042] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A single-layer three-band terahertz filtering metamaterial, characterized in that, It includes a metal layer and multiple artificial microstructure units formed by perforation within the metal layer, each artificial microstructure unit having at least one artificial microstructure. The upper and lower parts of each side of the artificial microstructure unit have rectangular grooves, so that a cross-shaped groove can be formed between every 2×2 adjacent artificial microstructure units. The artificial microstructure unit also includes a multi-curve "+"; The multiple "+" shaped grooves are formed by the intersection of 2n rectangular or arc-shaped grooves, where n is a positive integer greater than 1; Of the 2n grooves, 2n-1 longitudinal grooves do not intersect each other, and 1 transverse groove intersects with each of the 2n-1 longitudinal grooves.

2. The single-layer three-band terahertz filtering metamaterial according to claim 1, characterized in that, The metal layer is molybdenum or copper.

3. The single-layer three-band terahertz filtering metamaterial according to claim 1, characterized in that, The i-th groove and the (2n-i)-th groove are mirror symmetrical about the n-th groove in the 2n-1 longitudinal grooves, where i is a positive integer and i = 1. <n。 4. The single-layer three-band terahertz filtering metamaterial according to claim 1, characterized in that, The 2n-1 longitudinal grooves maintain at least two different groove lengths to form resonators with different resonant frequencies.

5. The single-layer three-band terahertz filtering metamaterial according to claim 1, characterized in that, The entire artificial microstructure unit is an axisymmetric figure, symmetrical about one horizontal groove and about the nth vertical groove.

6. The single-layer three-band terahertz filtering metamaterial according to claim 1, characterized in that, The artificial microstructure units are arranged in an array or periodically.

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