Ultra-wideband non-reciprocal wave absorber based on geometric inclined metal structure

Abstract

The invention discloses an ultra wide band non-reciprocal wave absorber based on a geometric gradient inclined metal structure, the structure is composed of periodic height increasing inclined layer units, conductive patches are pasted on the side surfaces, two layers of substrates are respectively arranged above and below the structure, a supporting surface is arranged behind the structure, and the supporting surface is made of polyimide. The inclined layer structure comprises a metal layer, a dielectric layer and an air cavity. The overall structure of the wave absorber is composed of ten units, each unit is composed of six basic inclined layers, a certain air cavity thickness is kept between the units, and the units are arranged in a height increasing mode. An inclined structure is used for breaking the symmetry of the dielectric constant tensor of a dispersion material, when each unit is arranged in a height increasing manner, different resonance units are formed, and the units are used for matching electromagnetic waves with different frequencies, so that a single absorption peak is stretched into an absorption band covering a plurality of frequencies, and the quintuple-frequency working bandwidth is realized; the non-reciprocal frequency band is broadened, the integration level is improved, and the use scene is expanded.

Description

Technical Field

[0001] The present invention relates to the field of non-reciprocity, and in particular to an ultra-wideband non-reciprocal absorber based on a geometrically inclined metal structure. Background Art

[0002] By studying the dispersion of specialized materials, deriving transmission matrices, and calculating their transmittance and absorptivity, we have designed a metamaterial plate composed of an array of tilted metal layers. Given specific conditions and two opposing orientations, this structure achieves full absorption in one direction and full transmission in the other, demonstrating its ability to function as a perfect nonreciprocal absorber. This structure, capable of absorbing detection signals while remaining transparent to its own signals, holds great potential for applications in energy and environmental protection, military communications, and civil security.

[0003] Nonreciprocal absorbers have extensive and important practical applications in various fields, particularly in stealth and anti-interference capabilities. They can reject interfering signals while maintaining the transmission of their own useful signals. This is particularly true in warfare, where they can absorb enemy detection signals while allowing friendly signals to transmit. If transmitted or reflected light is used as the output signal, a nonreciprocal absorber becomes an all-optical diode capable of optical logic functions, playing a crucial role in the development of future photonic computers.

[0004] After searching, it was found that the Chinese patent with publication number CN119511565A disclosed on February 25, 2025, a tunable non-reciprocal absorber based on a graphene-Weyl semimetal plasmon structure. The non-reciprocal absorber can adjust the graphene plasmon mode by appropriately adjusting the graphene Fermi level and the angle of incident light, thereby realizing the regulation of the non-reciprocal absorption efficiency, achieving dynamic tuning and enhancing the practicality of non-reciprocal devices.

[0005] It can be seen that dynamic adjustment and absorption efficiency are major considerations for non-reciprocal absorbers. Traditional non-reciprocal absorbers cannot achieve ideal complete absorption and transmission, but the non-reciprocal absorber under this design structure can achieve complete absorption and transmission at specific angles within a certain band. Moreover, this absorption and transmission does not require the assistance of traditional external magnetic fields, thereby enabling the miniaturization and integration of devices, providing a more powerful functional foundation for the application of stealth materials. Compared with the above-mentioned patents, this structure is simpler to adjust according to actual conditions, that is, it has greater adaptability and flexibility. In addition, in terms of materials, this structure is easier to obtain and has lower costs, which is more conducive to widespread use in civilian and military applications. Summary of the Invention

[0006] To overcome the shortcomings of the above-mentioned technologies, the present invention provides an ultra-wideband non-reciprocal absorber based on a geometrically tilted metal structure. The non-reciprocal absorber is designed based on a periodic arrangement of tilted layers. The tilt is used to change the symmetry of the material's dielectric constant tensor. The arrangement of the tilted layers and the air cavity is used to couple different resonant units. The unit height is arranged in increasing increments to widen a single absorption peak into a wide bandwidth. Ultimately, a non-reciprocal absorber with an operating bandwidth reaching quintuple frequency is formed, and both forward absorption and backward transmission reach over 90%.

[0007] The present invention is achieved through the following technical solutions:

[0008] An ultra-wideband non-reciprocal absorber based on a geometrically tilted metal structure includes a tilted layer unit array, which is composed of tilted layer units with periodic arrangement of basic tilted layers. The height of the tilted layer units increases, and the tilted structure breaks the symmetry of the dielectric constant tensor of the dispersive material. When arranged in increasing height, different resonance units are formed and match electromagnetic waves of different frequencies, so that a single absorption peak is stretched into an absorption band covering multiple frequencies. Specifically, there are 10 tilted layer units, and each tilted layer unit is composed of 5 basic tilted layers. The basic tilted layers are composed of a metal layer, a dielectric layer and an air cavity arranged in sequence. The metal layer and dielectric layer materials are indium tin oxide and calcium fluoride, respectively. Light is incident at an oblique angle.

[0009] Furthermore, when electromagnetic waves are incident from the air, the dielectric constant inside the material becomes asymmetric due to the tilted structure. This asymmetric dielectric constant tensor causes the wave vector components of the electromagnetic wave in two opposite propagation directions to change, thereby changing the propagation constant of the electromagnetic wave inside the metamaterial, and thus making the propagation and attenuation characteristics of the electromagnetic wave different.

[0010] Furthermore, when electromagnetic waves with a frequency of 31.95thz-167.4thz were incident at an angle of 50 degrees from the normal, the structure showed obvious non-reciprocity, and the forward absorptivity and backward transmittance simultaneously reached above 0.9.

[0011] Furthermore, the basic tilted layer arrangement order of the absorber is indium tin oxide-calcium fluoride-air, and each unit ends with indium tin oxide.

[0012] Furthermore, the absorber is effective for TM mode electromagnetic waves.

[0013] Furthermore, indium tin oxide is prepared by magnetron sputtering, calcium fluoride is prepared by molecular beam epitaxy, indium tin oxide is described by a Drude model, and calcium fluoride is described by a Sellmeier dispersion model.

[0014] Furthermore, the thickness of a single layer of indium tin oxide is 10 nm, the thickness of a single layer of calcium fluoride is 10 nm, the thickness of a single layer of air cavity is 40 nm, the tilt angle is 45 degrees, the height is arranged in increments of 200 nm, and the air cavity thickness is maintained between 330 nm and 3000 nm between the tilted layer units.

[0015] Compared with the prior art, the present invention has the following technical effects:

[0016] (1) The present invention uses a geometrically gradient tilted layer structure to replace the traditional principle of forming non-reciprocity using the magneto-optical effect. It does not require an external magnetic field and can achieve a good non-reciprocity phenomenon in the high frequency band.

[0017] (2) Combined with air cavities, they are arranged at different heights to achieve coupling of different resonance units. An ultra-wideband non-reciprocal absorber is realized by a geometrically asymmetric method, with an operating bandwidth of 5 times the frequency.

[0018] (3) The present invention is effective for TM mode electromagnetic waves.

[0019] (4) The maximum size of the present invention reaches the micron level, achieving miniaturization and being suitable for industrial integration. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 2 is a structural diagram of an ultra-wideband non-reciprocal absorber based on a geometrically inclined metal structure according to an embodiment of the present invention.

[0021] Figure 2 1 is a structural diagram of a tilted layer unit in an ultra-wideband non-reciprocal absorber based on a geometrically tilted metal structure according to an embodiment of the present invention.

[0022] Figure 3 2 is a main body diagram of an ultra-wideband non-reciprocal absorber based on a geometrically inclined metal structure according to an embodiment of the present invention.

[0023] Figure 4 Graph showing the non-reciprocal phenomenon of an ultra-wideband non-reciprocal absorber based on a geometrically inclined metal structure according to an embodiment of the present invention.

[0024] List of reference numerals:

[0025] 1- inclined layer unit, 2- substrate, 3- support plate, 4- conductive patch 1, 5- conductive patch 2 DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions of various embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0027] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0028] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art in the art to which this invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art and, unless defined as such, will not be interpreted in an idealized or overly formal sense.

[0029] The present invention is an ultra-wideband non-reciprocal absorber based on a geometrically inclined metal structure. Figure 1 As shown, it includes a main body and a support layer portion. The main body includes an array of inclined layer units, which is composed of periodically arranged inclined layer units 1. The support structure includes a base plate 2 arranged above and below, an I-shaped plate arranged on the left and right, and a support plate 3 placed on the rear side, all of which are made of polyimide. The I-shaped plate on the side is affixed with conductive patches (4, 5). Electromagnetic waves are incident at an oblique angle. When passing through the structure in the forward direction, the electromagnetic waves are absorbed by the structure. When passing through the structure in the backward direction, the electromagnetic waves can pass through the structure.

[0030] Basic tilted layers, e.g. Figure 2 As shown, the thickness of a single layer of indium tin oxide is 10 nm, the thickness of a single layer of calcium fluoride is 10 nm, the thickness of a single layer of air cavity is 40 nm, and the tilt angle is 45 degrees, forming a basic tilt layer structure. Five basic tilt layers form a tilt layer unit, and each unit ends with an indium tin oxide tilt layer.

[0031] The absorber main structure, such as Figure 3As shown, 10 units are arranged in an increasing height of 200 nm, with a starting height of 2000 nm, and the tilt angle of each unit remains unchanged.

[0032] like Figure 3 As shown, when electromagnetic waves are incident in TM mode at an oblique angle of 50 degrees from the normal, electromagnetic waves with a frequency of 31.95thz to 167.4thz will exhibit obvious non-reciprocal phenomenon, and the forward absorptivity and backward transmittance will reach above 0.9 at the same time.

[0033] After a specific design (using geometric gradient to break the symmetry of the dielectric constant of the material), the present invention can realize the function of non-reciprocal transmission. The present invention has a higher absorptivity, a higher transmittance and a wider working bandwidth.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention.

Claims

1. An ultra-wideband non-reciprocal absorber based on a geometrically inclined metal structure, characterized in that: The invention comprises an array of inclined layer units, which is composed of inclined layer units with periodic arrangement of basic inclined layers. The height of the inclined layer units is in an increasing trend. The symmetry of the dielectric constant tensor of the dispersion material is broken by the inclined structure. When the height is arranged in increasing order, different resonance units are formed, and electromagnetic waves of different frequencies are matched, so that a single absorption peak is stretched into an absorption band covering multiple frequencies. Specifically, there are 10 inclined layer units, and each inclined layer unit is composed of 5 basic inclined layers. The basic inclined layer is composed of a metal layer, a dielectric layer and an air cavity arranged in sequence. The materials of the metal layer and the dielectric layer are indium tin oxide and calcium fluoride, respectively. The light is incident at an oblique angle.

2. The ultra-wideband non-reciprocal absorber based on a geometrically inclined metal structure according to claim 1, characterized in that: When electromagnetic waves are incident from the air, the dielectric constant inside the material becomes asymmetric due to the tilted structure. This asymmetric dielectric constant tensor causes the wave vector components of the electromagnetic wave in two opposite propagation directions to change, thereby changing the propagation constant of the electromagnetic wave inside the metamaterial, and thus making the propagation and attenuation characteristics of the electromagnetic wave different.

3. The ultra-wideband non-reciprocal absorber based on a geometrically inclined metal structure according to claim 1, characterized in that: When electromagnetic waves with a frequency of 31.95thz-167.4thz were incident at an angle of 50 degrees from the normal, the structure showed obvious non-reciprocity, and the forward absorptivity and backward transmittance simultaneously reached above 0.

9.

4. The ultra-wideband non-reciprocal absorber electromagnetic device based on a geometrically inclined metal structure according to claim 1, characterized in that: The basic tilted layer arrangement order of the absorber is indium tin oxide-calcium fluoride-air, and each unit ends with indium tin oxide.

5. The ultra-wideband non-reciprocal absorber based on a geometrically inclined metal structure according to claim 1, characterized in that: The absorber is effective for TM mode electromagnetic waves.

6. The ultra-wideband non-reciprocal absorber based on a geometrically inclined metal structure according to claim 1, characterized in that: Indium tin oxide is prepared by magnetron sputtering, calcium fluoride is prepared by molecular beam epitaxy, indium tin oxide is described by the Drude model, and calcium fluoride is described by the Sellmeier dispersion model.

7. The ultra-wideband non-reciprocal absorber based on a geometrically inclined metal structure according to claim 1, characterized in that: The thickness of a single layer of indium tin oxide is 10nm, the thickness of a single layer of calcium fluoride is 10nm, the thickness of a single layer of air cavity is 40nm, the tilt angle is 45 degrees, the height is arranged in increments of 200nm, and the air cavity thickness between the tilted layer units is maintained at 330nm to 3000nm.

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