阅读说明：本技术 一种基于TiNi形状记忆合金薄膜的可动态调控的多功能太赫兹超材料器件 (Dynamically-adjustable multifunctional terahertz metamaterial device based on TiNi shape memory alloy film ) 是由 张琨 谭昌龙 刘娟 田晓华 黄跃武 赵文彬 于 2020-12-17 设计创作，主要内容包括：一种基于TiNi形状记忆合金薄膜的可动态调控的多功能太赫兹超材料器件。本发明涉及太赫兹超材料功能器件领域,具体涉及一种基于TiNi形状记忆合金薄膜的可动态调控的多功能太赫兹超材料器件。本发明是为解决现有太赫兹超材料存在的结构复杂、调控范围受限以及器件功能单一的问题。它包括衬底和开口谐振环结构薄膜层；所述开口谐振环结构薄膜层包括N×N个开口谐振环结构周期单元,所述开口谐振环结构周期单元包括一个单开口谐振环结构和对称设置在单开口谐振环结构开口处的两个可弯曲臂结构。本发明用于可动态调控的多功能太赫兹超材料器件。(A multifunctional terahertz metamaterial device based on a TiNi shape memory alloy film and capable of being dynamically regulated and controlled. The invention relates to the field of terahertz metamaterial functional devices, in particular to a dynamically-adjustable multifunctional terahertz metamaterial device based on a TiNi shape memory alloy film. The invention aims to solve the problems of complex structure, limited regulation and control range and single function of a device in the existing terahertz metamaterial. The structure comprises a substrate and an open resonator ring structure film layer; the split-ring resonator thin film layer comprises N multiplied by N split-ring resonator periodic units, and each split-ring resonator periodic unit comprises a single split-ring resonator structure and two bendable arm structures symmetrically arranged at the position of the single split-ring resonator structure. The invention is used for a multifunctional terahertz metamaterial device capable of being dynamically regulated and controlled.)

1. The dynamically-adjustable multifunctional terahertz metamaterial device based on the TiNi shape memory alloy film is characterized by comprising a substrate (1) and an opening resonant ring structure film layer, wherein the opening resonant ring structure film layer is arranged on the upper surface of the substrate (1); the split ring structure thin film layer comprises NxN split ring structure periodic units, and each split ring structure periodic unit comprises a single split ring structure (2) and two bendable arm structures (3) symmetrically arranged at the split of the single split ring structure (2); the single-opening resonant ring structure (2) is square.

2. The TiNi shape memory alloy film-based dynamically-controllable multifunctional terahertz metamaterial device according to claim 1, wherein the substrate (1) is a low-doped high-resistance silicon substrate with a thickness of 5 μm.

3. The dynamically adjustable multifunctional terahertz metamaterial device based on the TiNi shape memory alloy thin film as claimed in claim 1, wherein the material of the split ring structure thin film layer is TiNi shape memory alloy.

4. The dynamically-adjustable multifunctional terahertz metamaterial device based on the TiNi shape memory alloy thin film as claimed in claim 3, wherein the material of the split-ring structure thin film layer is Ti₄₈Ni₅₂A shape memory alloy.

5. The TiNi shape memory alloy film-based dynamically-controllable multifunctional terahertz metamaterial device as claimed in claim 1, wherein the period of the split-ring structure thin film layer is 50 μm.

6. The TiNi shape memory alloy film-based dynamically-controllable multifunctional terahertz metamaterial device as claimed in claim 1, wherein the side length of the single-opening resonator ring structure (2) is 40 μm.

7. The TiNi shape memory alloy film-based dynamically-controllable multifunctional terahertz metamaterial device as claimed in claim 1, wherein the line width of the single-opening resonator ring structure (2) is 3 μm.

8. The TiNi shape memory alloy film-based dynamically-controllable multifunctional terahertz metamaterial device as claimed in claim 1, wherein the thickness of the single-opening resonator ring structure (2) is 40 nm.

9. The TiNi shape memory alloy film-based dynamically-controllable multifunctional terahertz metamaterial device as claimed in claim 1, wherein the gap between the two bendable arm structures (3) symmetrically arranged at the opening of the single-opening resonator ring structure (2) is 0.2 μm.

Technical Field

The invention relates to the field of terahertz metamaterial functional devices, in particular to a dynamically-adjustable multifunctional terahertz metamaterial device based on a TiNi shape memory alloy film.

Background

Terahertz (THz) waves are a unique electromagnetic spectrum that is between the microwave and infrared, combining the advantages of both spectral regions. The material has the characteristics of high-frequency field oscillation, low photon energy, high directivity, high transparency and the like in most material systems, and has wide application prospects in the fields of physical chemistry, material science, biomedicine, environmental science, safety inspection, satellite communication and the like. At present, the interaction between the terahertz wave and a natural material is extremely small, which directly results in the lack of the natural material for regulating and controlling the terahertz wave. The metamaterial (MMs) is an artificial material consisting of a metal or dielectric material sub-wavelength microarray, and provides a good solution for the regulation and control of terahertz waves due to the singular electromagnetic response characteristic of the metamaterial. In recent years, researchers have made a lot of research on terahertz switches, converters, wave absorbers, and the like using metamaterials. In the past, terahertz components based on metamaterial are all made of metal materials, and after the processing size is fixed, the functions of the components are difficult to actively change in practical application. Therefore, the development of the actively-controlled terahertz component has important research significance.

Currently, the realization of active regulation of terahertz waves is mainly based on two different modes: based on the change in the properties of the material itself and on the effect of the structural deformation. However, each of these two active control methods has advantages and disadvantages: the disadvantage of varying based on material properties is that the modulation range is limited; the methods based on the structural deformation effect rely heavily on complex structures, and thus are complex to process and manufacture. In addition, the methods are limited to actively controlling a single parameter, so that the currently researched terahertz active control device has a single function, namely, the terahertz active control device can only realize a single function under a single external field. But the single function is difficult to adapt to the requirements of the current technology development. Therefore, on a single device, the regulation and control of multiple physical fields and the multifunctional regulation and control of terahertz waves are realized, which is one of the development fronts of the current terahertz technology and is a practical requirement of practical application.

Disclosure of Invention

The invention provides a dynamically-controllable multifunctional terahertz metamaterial device based on a TiNi shape memory alloy film, which aims to solve the problems of complex structure, limited regulation range and single device function of the existing terahertz metamaterial.

The dynamically-adjustable multifunctional terahertz metamaterial device based on the TiNi shape memory alloy film comprises a substrate and an open resonator ring structure film layer, wherein the open resonator ring structure film layer is arranged on the upper surface of the substrate; the split-ring structure thin film layer comprises NxN split-ring structure periodic units, and each split-ring structure periodic unit comprises a single split-ring structure and two bendable arm structures symmetrically arranged at the split of the single split-ring structure; the single-split resonant ring structure is square.

The invention has the beneficial effects that:

1. the invention can realize the dynamic control of the resonant frequency and amplitude in the transmission curve by utilizing the conductivity adjustability of the shape memory alloy. The phase change and recoverable superelastic deformation of the metamaterial in the structural unit are driven by a thermal field or a magnetic field, and the combination of the change of the material property and the change of the macroscopic structure in the structural unit is realized, so that the electromagnetic response of the metamaterial is tuned.

2. The invention can realize the effect of double-band filtering, and simultaneously realize the filtering effect of 99.8 percent at most on the basis of LC resonance and dipole resonance.

3. On the basis of filtering, the invention can also realize the switching function and has a switching effect on the initial and final states of modulation. The transmittance in the on state is an order of magnitude higher than the transmittance in the off state.

Drawings

FIG. 1 is a schematic structural diagram of a dynamically-adjustable multifunctional terahertz metamaterial device based on a TiNi shape memory alloy film; wherein 1 is a substrate, and 2 is a single-opening resonant ring structure;

FIG. 2 is a schematic structural diagram of a single-split resonant ring structure according to an embodiment; wherein 1 is a substrate, 2 is a single-opening resonant ring structure, and 3 is a bendable arm structure;

FIG. 3 is a top view of a single open resonator ring structure according to an embodiment;

FIG. 4 is a side view of a single open resonator ring structure according to one embodiment;

FIG. 5 is a schematic diagram illustrating the dynamic variation of the flexible arm structure with temperature when a temperature field is applied to the single-split resonant ring structure according to an embodiment;

FIG. 6 shows an embodiment of a dynamically adjustable multifunctional terahertz metamaterial device based on a TiNi shape memory alloy thin film, wherein the conductivity of the device is 1.25 × 10⁵A transmission curve variation diagram at S/m;

FIG. 7 shows an embodiment of a dynamically adjustable multifunctional terahertz metamaterial device based on a TiNi shape memory alloy thin film, wherein the conductivity of the device is 5.25 × 10⁵A transmission curve variation diagram at S/m;

FIG. 8 shows an embodiment of a dynamically adjustable multifunctional terahertz metamaterial device based on a TiNi shape memory alloy thin film, wherein the conductivity of the device is 8.25 × 10⁵A transmission curve variation diagram at S/m;

FIG. 9 shows an embodiment of a dynamically adjustable multifunctional terahertz metamaterial device based on a TiNi shape memory alloy thin film, wherein the conductivity of the device is 1.25 × 10⁶A transmission curve variation diagram at S/m;

fig. 10 is a graph illustrating a change of a transmission curve of a bending angle of a bendable arm structure of a dynamically-controllable multifunctional terahertz metamaterial device based on a TiNi shape memory alloy thin film, which is increased from 0 ° to 10 °, wherein 1 denotes 0 °, 2 denotes 2 °, 3 denotes 4 °, 4 denotes 6 °, 5 denotes 8 °, 6 denotes 10 °;

FIG. 11 is a transmission curve variation diagram illustrating that the conductivity and the deformation of the dynamically adjustable multifunctional terahertz metamaterial device based on the TiNi shape memory alloy thin film are changed simultaneously; wherein the dotted line indicates a conductivity of 1.25X 10⁵S/m and the deformation angle are 0 degree; the solid line shows a conductivity of 1.25X 10⁶S/m and the deformation angle are 10 deg.

Detailed Description

The first embodiment is as follows: as shown in fig. 1 to 3, the dynamically-controllable multifunctional terahertz metamaterial device based on the TiNi shape memory alloy thin film according to the present embodiment includes a substrate 1 and an open-ring resonator structure thin film layer, where the open-ring resonator structure thin film layer is disposed on an upper surface of the substrate 1; the split ring structure thin film layer comprises NxN split ring structure periodic units, and each split ring structure periodic unit comprises a single split ring structure 2 and two bendable arm structures 3 symmetrically arranged at the split of the single split ring structure 2; the single-split resonator ring structure 2 is square.

The Shape Memory Alloy (SMA) of the present embodiment is one of the most typical metal smart materials, and realizes deformation recovery through martensite transformation under the action of an applied field. Shape memory alloys have found increasingly widespread use in many applications due to their "strain sensing and actuation integration" characteristics. The martensitic phase transformation behavior of SMA leads to two different macroscopic effects: geometric distortion and changes in properties such as resistance, dielectric constant, etc., which correspond exactly to two active control modes for THz waves. SMA has the advantages of large deformation, high sensitivity, simple structure and the like. Therefore, the strategy of introducing the memory alloy into the terahertz MMs not only can realize multifunctional control on terahertz waves, but also is beneficial to realizing new functional characteristics.

According to the embodiment, by designing a brand-new metamaterial device based on the Ti48Ni52 shape memory alloy film and utilizing the adjustability of phase change and deformation before and after martensite phase change of the shape memory alloy, the metamaterial device is simple in design structure and convenient to process, can realize dual functions of a double-band filter and a terahertz switch with excellent performance in the same device, has dynamically adjustable performance, and greatly meets the application requirement on terahertz regulation.

According to the implementation mode, when a certain external temperature field is applied, the conductivity of the TiNi alloy film and the tilting height of the bendable arm structure can be regulated, and the conductivity and the tilting angle of the TiNi alloy film cantilever beam can be flexibly tuned by changing the temperature of the external field to form different reconstruction states; by changing the reconstruction state of the TiNi-based shape memory alloy film terahertz metamaterial, the absorption bandwidth, the strength and the frequency of terahertz can be flexibly regulated and controlled.

Most of the structural units of the metamaterial are made of metals such as gold, silver, aluminum and the like, once the structure is fixed, the tuning performance is limited, the process complexity is increased by combining with other tunable materials, the structural units can be directly made of shape memory alloy ultrathin films deposited on silicon, and the process is simple.

The second embodiment is as follows: the first difference between the present embodiment and the specific embodiment is: the substrate 1 is a low-doped high-resistance silicon substrate, the thickness of the substrate is 5 mu m, and the dielectric constant of the substrate is 11.86. Other steps and parameters are the same as those in the first embodiment.

The third concrete implementation mode: the present embodiment differs from the first or second embodiment in that: the opening resonant ring structure thin film layer is made of TiNi shape memory alloy. Other steps and parameters are the same as those in the first or second embodiment.

The fourth concrete implementation mode: the difference between this embodiment mode and one of the first to third embodiment modes is: the opening resonant ring structure thin film layer is made of Ti₄₈Ni₅₂A shape memory alloy. Other steps and parameters are the same as those in one of the first to third embodiments.

The material of the thin film layer for limiting the open-ended resonant ring structure of the present embodiment is Ti₄₈Ni₅₂The shape memory alloy is based on the reason that the conventional applicable environment temperature of the terahertz device is room temperature, and the martensite phase transformation temperature of the shape memory alloy is in a room temperature environment.

The fifth concrete implementation mode: the difference between this embodiment and one of the first to fourth embodiments is: the period of the thin film layer of the split ring structure is 50 μm. Other steps and parameters are the same as those in one of the first to fourth embodiments.

The sixth specific implementation mode: the difference between this embodiment and one of the first to fifth embodiments is: the side length of the single-opening resonant ring structure 2 is 40 mu m. Other steps and parameters are the same as those in one of the first to fifth embodiments.

The seventh embodiment: the difference between this embodiment and one of the first to sixth embodiments is: the line width of the single-opening resonant ring structure 2 is 3 μm. Other steps and parameters are the same as those in one of the first to sixth embodiments.

The specific implementation mode is eight: the present embodiment differs from one of the first to seventh embodiments in that: the thickness of the single-opening resonant ring structure 2 is 40 nm. Other steps and parameters are the same as those in one of the first to seventh embodiments.

The specific implementation method nine: the present embodiment differs from the first to eighth embodiments in that: the gap between the two bendable arm structures 3 symmetrically arranged at the opening of the single-opening resonant ring structure 2 is 0.2 μm. Other steps and parameters are the same as those in one to eight of the embodiments.

The beneficial effects of the present invention are demonstrated by the following examples:

the first embodiment is as follows: the dynamically-adjustable multifunctional terahertz metamaterial device based on the TiNi shape memory alloy film comprises a substrate 1 and an open resonator ring structure film layer, wherein the open resonator ring structure film layer is arranged on the upper surface of the substrate 1; the split ring structure thin film layer comprises NxN split ring structure periodic units, and each split ring structure periodic unit comprises a single split ring structure 2 and two bendable arm structures 3 symmetrically arranged at the split of the single split ring structure 2; the single-split resonator ring structure 2 is square. The substrate 1 is a low-doped high-resistance silicon substrate, and the thickness of the substrate is 5 micrometers; the opening resonant ring structure thin film layer is made of Ti₄₈Ni₅₂A shape memory alloy.

The period of the structural units of the periodic array is a, which is 50 μm in the present embodiment; the gap between the two bendable arm structures 3 symmetrically arranged at the opening of the single-opening resonant ring structure 2 is d, which is 0.2 μm in the embodiment; the side length of the single-opening resonant ring is l, and the side length is 40 mu m in the embodiment; the line width of the single-opening resonant ring structure 2 is t, and in the embodiment, the line width is 3 μm; the thickness of the single-aperture resonator ring structure 2 is 40 nm.

The implementation case can generate LC resonance and electric dipole resonance at the same time, and because the conductivity of the TiNi shape memory alloy can be realized by adjusting the excitation of external temperature, and the temperature and the conductivity have a specific relation, the dynamic modulation of the LC resonance and the electric dipole resonance based on the TiNi shape memory alloy metamaterial can be realized by changing the conductivity in the simulation.

As can be seen from FIGS. 6 to 9, when the conductivity is 1.25X 10⁵At S/m, the transmittance of 0.29THz wave is 0.42, and the transmittance of 1.23THz wave is 0.07; when the conductivity is 5.25X 10⁵At S/m, the transmittance of 0.29THz wave is 0.41, and the transmittance of 1.23THz wave is 0.06; when the conductivity is 8.25X 10⁵At S/m, the transmittance of 0.29THz wave is 0..40, and the transmittance of 1.23THz wave is 0.05; when the conductivity is 1.25X 10⁶The transmittance of 0.29THz wave at S/m was 0.39, and the transmittance of 1.23THz wave was 0.05.

The electromagnetic performance can be changed by changing the shape of the TiNi shape memory alloy thin film cantilever beam, the electromagnetic performance can be obtained from the graph shown in FIG. 4 and FIG. 5, the terahertz metamaterial based on the TiNi shape memory alloy can be deformed by temperature excitation, the angle theta of the bendable cantilever is changed, the equivalent length le 'is shortened, the opening size is changed from d to d', different reconstruction structures are formed, and the frequency, the bandwidth and the amplitude of a transmission curve can be flexibly regulated and controlled by changing the structure of the metamaterial based on the TiNi shape memory alloy.

As can be seen from fig. 10, when the tilt angle of the TiNi shape memory alloy thin film cantilever is 0 °, the transmittance of the 0.29THz wave is 0.42, and the transmittance of the 1.23THz wave is 0.07; when the tilting angle of the TiNi shape memory alloy film cantilever beam is 2 degrees, the transmissivity of 0.29THz wave is 0.43, and the transmissivity of 1.23THz wave is 0.12; when the tilting angle of the TiNi shape memory alloy film cantilever beam is 4 degrees, the transmissivity of 0.29THz wave is 0.5, and the transmissivity of 1.23THz wave is 0.22; when the tilting angle of the TiNi shape memory alloy film cantilever beam is 6 degrees, the transmissivity of 0.29THz wave is 0.56, and the transmissivity of 1.23THz wave is 0.33; when the tilting angle of the TiNi shape memory alloy film cantilever beam is 8 degrees, the transmissivity of 0.29THz wave is 0.58, and the transmissivity of 1.23THz wave is 0.47; when the tilting angle of the TiNi shape memory alloy film cantilever beam is 10 degrees, the transmissivity of 0.29THz wave is 0.62, and the transmissivity of 1.23THz wave is 0.5.

From FIG. 11, it can be seen that when the conductivity of the TiNi-based shape memory alloy metamaterial is changed simultaneously with the cantilever beam tilt angle, the conductivity of the shape memory alloy metamaterial is changed from 1.25 × 10⁵S/m variation 1.25X 10⁶S/m, meanwhile, the bending angle of the bendable part is changed from 0 degree to 10 degrees, two resonance peaks of a transmission curve are changed from 0.29THz and 1.23THz to 0.47THz and 1.79THz, and transmission and real-time regulation and control of terahertz waves with different frequencies are achieved, so that the phase change of the TiNi shape memory alloy metamaterial is utilized, and dynamic tuning is possible.

In addition, a switch with a switch effect is formed at 0.47THz, when TiNi shape memory alloy generates martensite phase transformation under the action of a temperature field, the transmissivity of the terahertz wave at 0.47THz can be tuned from 0.78 to 0.04, and the transmissivity between two states is different by more than one order of magnitude, so that the switch has the basis of excellent switching. Therefore, in the TiNi shape memory alloy metamaterial, the versatility of terahertz modulation is realized.