CN214849067U

CN214849067U - Broadband terahertz wave absorber

Info

Publication number: CN214849067U
Application number: CN202121027028.6U
Authority: CN
Inventors: 金风阳; 郎婷婷; 王金凤
Original assignee: China Jiliang University
Current assignee: China Jiliang University
Priority date: 2021-05-10
Filing date: 2021-05-10
Publication date: 2021-11-23
Anticipated expiration: 2031-05-10

Abstract

The utility model discloses a broadband terahertz wave absorber, which comprises a metal substrate layer, a first dielectric layer, a first square metal layer, a second dielectric layer, a second square metal layer and a third dielectric layer from bottom to top in sequence; the two square metal layers are surrounded by the medium layer SU-8 photoresist, the SU-8 is a loss medium, and the dielectric constant is 2.79-0.31 i; the metal substrate layer is thick enough to prevent terahertz waves from penetrating. The Fabry-Perot resonant cavities with different modes of the terahertz wave absorber are coupled with surface plasmas through gaps of the resonant cavities to generate a broadband wave absorbing effect. The wave absorber structure can realize good absorption effect, and the absorption rate of the wave absorber structure is greater than 90% of the absorption bandwidth 1.74 THz. The utility model discloses the low price and absorption effect are better. The method is suitable for electromagnetic anti-interference and modern communication systems.

Description

Broadband terahertz wave absorber

Technical Field

The utility model relates to an electromagnetic wave absorbs the wave field, especially relates to a broadband terahertz wave absorber now.

Background

A metamaterial wave absorber is a device with a periodic sub-wavelength structure and high absorption rate to incident electromagnetic energy. Each type of absorber has its own different frequency response, depending on their geometry and constituent materials. At present, the wave absorber can be used for single-band, multi-band and broadband, the working frequency of the wave absorber is in the microwave, terahertz, infrared, visible light and ultraviolet light wave ranges, and meanwhile, the wave absorber is also applied to the fields of sensors, solar cells, stealth, imaging and the like. The designed wave absorber with wide wave absorbing working bandwidth and easy manufacturing and processing has very important application value in the terahertz field.

In the field of electromagnetic wave absorption, a wave absorber needs to have broadband characteristics, and researchers propose various broadband wave absorbers for the wave absorber, wherein the broadband wave absorbers comprise a diffraction grating silicon-based wave absorber, a metal-insulator-metal resonator wave absorber, a graphene-based wave absorber and the like. The graphene wave absorber can realize adjustable broadband, but provides higher requirements for the graphene manufacturing process and does not meet the requirements of wide application; although silicon-based absorbers are generally broadband, such absorbers suffer from the disadvantage of being of excessive thickness. For broadening of these absorber bands, various methods have been proposed, most commonly metal resonators of different sizes are arranged horizontally or vertically in periodic units to achieve broadband absorption. Currently, vertically stacked wave absorbers generally have a wider bandwidth than other types of wave absorbers.

In recent years, good results are obtained on the technical research of broadband wave absorbers. In 2019, 5, 13.s, electronics and technology university provides a 'terahertz frequency band broadband metamaterial wave absorber' with application number of 201910394187.0, which comprises a metal substrate, a dielectric layer and a metal resonance layer, wherein the metal resonance layer is provided with four pairs of parallel channels, and a capacitive coupling principle is formed by introducing capacitive coupling channels to generate a wave absorbing effect. In 30/6/2020, the academy of the anyang university proposed "a design of a broadband metamaterial absorber" with application number of 202010648805.2, the structure of which comprises a metal layer, a dielectric layer and a structured graphene layer, and the structure is simple and easy to process but has the defect of narrow working bandwidth.

In order to solve the problem, the utility model provides a broadband terahertz wave absorber to satisfy at present the demand to this type of broadband wave absorber in terahertz detection field.

Disclosure of Invention

To the above-mentioned problem that exists among the prior art, the utility model provides a broadband terahertz wave absorber now.

The utility model adopts the following technical scheme:

the technical principle of the utility model is that: the Fabry-Perot resonant cavities in different modes are coupled with surface plasmas through gaps of the resonant cavities to generate a broadband wave absorbing effect.

Preferably, firstly, depositing 110 nm thick chromium on the cleaned silicon wafer by using an electron beam evaporation method to form the metal substrate layer 1; secondly, coating liquid photoresist SU-8 on the chromium surface in a rotating manner, and baking the soft SU-8 to form the first dielectric layer 2; thirdly, manufacturing a square metal layer pattern through a photoetching process; fourthly, depositing a second 110 nanometer thick chromium layer through electron beam evaporation, and then forming the first square metal layer 3 through a stripping process; fifthly, another layer of liquid photoresist SU-8 is coated on the first square metal layer 3 in a rotating mode to form a second dielectric layer 4; sixthly, manufacturing a square metal layer pattern through the photoetching process again; seventhly, depositing a third 110-nanometer-thick chromium layer through electron beam evaporation, and then forming the second square metal layer 5 through a stripping process; and eighthly, rotationally coating the last layer of liquid photoresist SU-8 on the second square metal layer 5 to form the third dielectric layer 6.

Preferably, the broadband terahertz wave absorber sequentially comprises a metal substrate layer, a first dielectric layer, a first square metal layer, a second dielectric layer, a second square metal layer and a third dielectric layer from bottom to top; two square metal layers are embedded in the SU-8 photoresist, and the uppermost dielectric layer can protect the chromium resonator from oxidation and further improve the absorption bandwidth of the wave absorber; the two square metal layers are aligned through geometric centers to form the terahertz wave absorber which is arranged periodically.

Preferably, the metal substrate layer and the two square metal layers are made of metal chromium, and the conductivity is 8 multiplied by 10⁶S/m; the dielectric layers are all SThe dielectric constant of the U-8 photoresist is 2.79-0.31 i.

Preferably, the structural period p of the wave absorber unit is 101 microns; the thicknesses of the metal substrate layer 1, the first square metal layer 3 and the second square metal layer 5 are all 110 nanometers; the width w1 of the first square metal layer 3 is 76 microns, and the width w2 of the second square metal layer 5 is 41 microns; the thickness h1 of the first dielectric layer 2 is 22 microns, the thickness h2 of the second dielectric layer 4 is 22 microns, and the thickness h3 of the third dielectric layer 6 is 20 microns.

Preferably, the working wave band of the wave absorber structure is 1.5-3.5 THz.

The utility model discloses following beneficial effect has:

1. the absorption bandwidth that the broadband terahertz wave absorbing device absorptivity is greater than 90% is 1.74THz, has the absorptive characteristic of high absorptivity and broadband.

2. Broadband terahertz wave absorber simple structure, compactness are convenient for large-scale integrated production now.

3. The proposed structure has symmetry and is therefore insensitive to detuning between the resonant cavities, also making its manufacture easy.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

Fig. 1 is a schematic view of a three-dimensional structure of wave absorbers periodically arranged in the embodiment of the present invention;

FIG. 2 is a diagram of a unit structure of a wave absorber in an embodiment of the present invention;

FIG. 3 is a side view of the unit structure of the wave absorber in the embodiment of the present invention;

fig. 4 is a top view of a unit structure of a wave absorber in an embodiment of the present invention;

FIG. 5 is a graph showing the absorption rate of the wave absorber as a function of frequency according to an embodiment of the present invention;

wherein, 1 is a metal substrate layer, 2 is a first dielectric layer, 3 is a first square metal layer, 4 is a second dielectric layer, 5 is a second square metal layer, and 6 is a third dielectric layer.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

In order to make the above objects, features and advantages of the present invention more comprehensible, the present invention is described in detail with reference to the accompanying drawings and the detailed description.

Fig. 1 is a schematic diagram of a three-dimensional structure of a broadband terahertz wave absorber, where the structure is a wave absorber formed by periodically arranging 100 × 100 square resonators.

As shown in fig. 2, the unit structure diagram of the broadband terahertz wave absorber includes, from bottom to top, a metal substrate layer 1, a first dielectric layer 2, a first square metal layer 3, a second dielectric layer 4, a second square metal layer 5, and a third dielectric layer 6 in sequence; the first square metal layer 3 and the second square metal layer 5 are surrounded by the first dielectric layer 2, the second dielectric layer 4 and the third dielectric layer 6; the metal layers are all made of metal chromium, and the dielectric layers are all made of SU-8 photoresist.

As shown in fig. 3, which is a side view of a unit structure of a terahertz wave absorber, a thickness h1 of the first dielectric layer 2 is 22 micrometers, a thickness h2 of the second dielectric layer 4 is 22 micrometers, and a thickness h3 of the third dielectric layer 6 is 20 micrometers.

As shown in fig. 4, in a top view of a unit structure of a terahertz wave absorber, a period p of the wave absorber unit structure is 101 micrometers, a width w1 of the second square metal layer 3 is 76 micrometers, and a width w2 of the second square metal layer 5 is 41 micrometers.

As shown in fig. 5, which is a graph showing the variation of the absorption rate of the wave absorber with frequency, it can be known from the graph that in the range of 1.5 to 3.5THz, the absorption bandwidth of more than 90% is 1.74THz, and the wave absorption bandwidth is wider, and the wave absorption principle is that the fabry-perot resonant cavities in different modes are coupled with surface plasma through the gaps of the resonant cavities to generate the broadband wave absorption effect.

In the description of the present invention, it is to be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "inner", "middle", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description of the present invention, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be construed as limiting the present invention.

The above-mentioned embodiments are only intended to describe the preferred embodiments of the present invention, but not to limit the scope of the present invention, and those skilled in the art should also be able to make various modifications and improvements to the technical solution of the present invention without departing from the spirit of the present invention, and all such modifications and improvements are intended to fall within the scope of the present invention as defined in the appended claims.

Claims

1. A broadband terahertz wave absorber is characterized in that: the metal substrate comprises a metal substrate layer (1), a first dielectric layer (2), a first square metal layer (3), a second dielectric layer (4), a second square metal layer (5) and a third dielectric layer (6) from bottom to top in sequence; the first square metal layer (3) and the second square metal layer (5) are aligned through geometric centers to form a terahertz wave absorber which is arranged periodically.

2. The broadband terahertz wave absorber according to claim 1, wherein: the metal substrate layer (1), the first square metal layer (3) and the second square metal layer (5) are all chromium metal, and the conductivity is8×10⁶S/m; the first dielectric layer (2), the second dielectric layer (4) and the third dielectric layer (6) are all SU-8 photoresist, and the dielectric constant of the first dielectric layer, the second dielectric layer and the third dielectric layer is 2.79-0.31 i.

3. The broadband terahertz wave absorber according to claim 1, wherein: the structural period of the wave absorber unit is 101 microns; the thicknesses of the metal substrate layer (1), the first square metal layer (3) and the second square metal layer (5) are all 110 nanometers; the width of the first square metal layer (3) is 76 micrometers, and the width of the second square metal layer (5) is 41 micrometers; the thickness of the first dielectric layer (2) is 22 microns, the thickness of the second dielectric layer (4) is 22 microns, and the thickness of the third dielectric layer (6) is 20 microns.

4. The broadband terahertz wave absorber according to claim 1, wherein: the working waveband of the wave absorber structure is 1.5-3.5 THz, and the absorption bandwidth with the absorption rate of more than 90% is 1.74 THz.