Phononic crystal controllable spin-orbit coupler for sound wave regulation and control

Abstract

The invention belongs to the field of acoustic metamaterial and acoustic information transmission, and particularly discloses a phononic crystal controllable spin-orbit coupler for acoustic wave regulation and control, which comprises a plurality of unit cells formed by periodic phononic crystal structures, each unit cell comprises four resonators, and the four resonators are identical hollow cylinders and are arranged according to tetragonal crystal lattices; and positive and negative coupled coupling tubes are fixedly connected among the four resonators and among the resonators of the adjacent unit cells. The device has a tunable topology protection effect acoustic edge state to realize sound wave control of a specific frequency, and also has the advantages of sound transmission robustness, easy preparation of materials, adjustability, directionality, structural stability and the like.

Description

Technical Field

[0001] The present invention belongs to the field of acoustic metamaterials and acoustic information transmission, and in particular relates to a phononic crystal controllable spin-orbit coupler for acoustic wave regulation. Background Art

[0002] Sound waves are everywhere in our daily life, and the most representative manifestations are car noise, sound information transmission, ultrasonic imaging, etc. However, traditional devices have certain limitations in regulating sound waves, mainly in terms of sound loss limitation, reciprocity limitation, and direction limitation. At present, the development of phononic crystal devices or acoustic metasurfaces is the best choice to solve these problems. However, acoustic metasurfaces have high manufacturing costs. For example, due to the thin size of acoustic metasurfaces, the precision and process requirements of manufacturing devices are high. In contrast, phononic crystals are an artificial composite material with a periodic structure that can regulate sound waves through Bragg scattering and local resonance effects, producing novel acoustic phenomena such as band gaps, negative refraction, super prism effects, super lens effects, and abnormal sound insulation effects. It can be achieved through 3D printing technology and has low manufacturing costs. However, traditional phononic crystals have certain limitations in regulating sound waves. For example, they are usually contactless in structure, which increases the instability of practical environments. Functionally, most phononic crystals can only produce a single edge localized state, which limits the application of acoustic information transmission. Therefore, we urgently need a controllable acoustic wave device with stable structure and rich functions.

[0003] Topological phononics is a frontier field in phononic crystal research. Researchers have achieved topologically protected phononic states by designing stable structures with coupled connections, realizing unidirectional transmission of sound waves and stable propagation that is immune to defects. This topologically protected phononic state exhibits unique physical phenomena in phononic crystals, providing new ideas and methods for acoustic wave control. Phononic crystals with topological protection are usually related to intrinsic controllable degrees of freedom, such as pseudo-spin degrees of freedom, orbital degrees of freedom, and spin-orbit coupling. By changing the coupling connection method to control the intrinsic degrees of freedom, it is possible to achieve rich acoustic topological protection states and stable structures. Not only that, compared with traditional phononic crystal devices, the presence of the coupling tube will also increase the mechanical stability of the structure, so that it can be applied to various complex and harsh environment scenarios. Therefore, there is a need for a phononic crystal controllable spin-orbit coupler for acoustic wave control to achieve efficient multi-state manipulation of acoustic waves, which is of great significance to fields such as acoustic wave control and quantum acoustic communication. Summary of the invention

[0004] In order to address the deficiencies in the prior art, the present invention aims to provide a phononic crystal controllable spin-orbit coupler for acoustic wave regulation. The device has a tunable topological protection effect acoustic edge state to achieve control of acoustic waves of a specific frequency. It also has the advantages of robustness of sound transmission, easy material preparation, adjustability, directionality and structural stability. It can be widely used in sound communication, acoustic information encryption, hydroacoustics, marine exploration, industrial non-destructive testing and other fields.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: A phononic crystal controllable spin-orbit coupler for sound wave regulation includes a plurality of unit cells formed by a periodic phononic crystal structure, wherein a single unit cell includes four resonators, and the four resonators are identical hollow cylinders and arranged in a tetragonal lattice; coupling tubes for positive and negative coupling are fixedly connected between the four resonators and between the resonators of adjacent unit cells.

[0006] Preferably, the number of the unit cells is at least 5, and the material is resin material.

[0007] Preferably, the spacing between the resonators is 4 mm; the cylindrical height of the resonator is 20 mm and the radius is 6 mm.

[0008] Preferably, the coupling tube includes four connecting tubes, and two adjacent resonators in the x-axis direction are connected via a first connecting tube and a second connecting tube respectively; and two diagonal resonators in the y-axis direction are connected via a third connecting tube and a fourth connecting tube respectively.

[0009] Preferably, the first connecting pipe is a straight pipe arranged obliquely, and the second connecting pipe is a V-shaped bent pipe with a certain angle.

[0010] Preferably, the inclination angle between the first connecting tube and the resonator is 30°, the distance from the end surface adjacent to the resonator is 2 mm, and the radius of the first connecting tube is 1 mm.

[0011] Preferably, the second connecting tube is symmetrically distributed along the midline of the interval between the two resonators, the bending angle of the second connecting tube is 62°, the distance from the end surface adjacent to the resonator is 2 mm, and the radius is 1 mm.

[0012] Preferably, the third connecting tube and the fourth connecting tube have the same size and are symmetrically arranged along the hypotenuse of the tetragonal lattice in the z-axis direction.

[0013] Preferably, the third connecting tube and the fourth connecting tube are V-shaped bent tubes, the bending directions of the third connecting tube and the fourth connecting tube are opposite, the bending angle is 92°, the distance from the end surface adjacent to the resonator is 2 mm, and the radius is 0.5 mm.

[0014] Preferably, the third connecting tube and the fourth connecting tube are straight tubes, the distance from the end surface close to the resonator is 2 mm, and the radius is 0.5 mm.

[0015] The present invention has the following beneficial effects: 1. The phononic crystal controllable spin-orbit coupler for acoustic wave regulation of the present invention has a mechanical manufacturing technology that is easy to prepare, and the weather resistance and corrosion resistance of the resin material make the phononic crystal controllable spin-orbit coupler of the present invention easy to maintain and have a long service life.

[0016] 2. The present invention introduces a spin-orbit coupling mechanism through the connection mode of the coupling tube, which not only improves the controllable freedom of the phononic crystal, but also increases the connection between the structures, greatly improving the stability of the structure.

[0017] 3. The spin-orbit coupler of the present invention determines four different localized states of acoustic waves near 8580 Hz, which are manifested as localized states with different positions and different numbers of localizations, which meets the needs of different application scenarios.

[0018] 4. The present invention utilizes the periodically arranged structural units of phononic crystals to realize acoustic edge states with topological protection effects, provides efficient control of sound waves of specific frequencies, and ensures the stability and robustness of sound transmission.

[0019] 5. The phononic crystal controllable spin-orbit coupler of the present invention has low backscattering loss for sound waves and can maintain stable sound wave transmission even in complex environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the structure of a single unit cell in Example 1 of the present invention; Figure 2 A top view of a single unit cell of Example 1 of the present invention; Figure 3 It is a front view of a single unit cell of Example 1 of the present invention; Figure 4 A schematic diagram of a one-dimensional spin-orbit coupler and sound detection composed of 14 unit cells according to Example 1 of the present invention; Figure 5 The position intensity amplitude and acoustic field distribution diagram of the phononic crystal controllable spin-orbit coupler of the present invention with respect to the topological mode (1, 0); Figure 6 The diagram is a distribution diagram of the acoustic field mode state of a specific frequency of the phononic crystal controllable spin-orbit coupler of the present invention under different topological modes.

[0021] Reference numerals: Figure 1-3Middle: A1. resonator, C2. first connecting pipe, C1. second connecting pipe, B1. third connecting pipe, B2. fourth connecting pipe.

[0022] Figure 5 In the figure, (a) indicates that the sound field is localized on the left, and (b) indicates that the sound field is localized on the right. DETAILED DESCRIPTION

[0023] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not intended to limit the scope of use of the present invention.

[0024] Embodiment 1: like Figure 1-3 As shown, the present invention proposes a phononic crystal controllable spin-orbit coupler for sound wave control, which aims to achieve precise control of sound waves to meet the application requirements of sound information processing and sound information encoding. The phononic crystal controllable spin-orbit coupler of the present invention has the advantages of simple structure and flexible control. It mainly distinguishes different coding states through coupling tubes, which is suitable for acoustic information processing equipment such as acoustic logic gates, acoustic antenna transmission and acoustic information encoding, and can provide new technical means for fields such as sound wave control, hydroacoustic ocean exploration and quantum acoustic communication.

[0025] The spin-orbit coupler includes multiple unit cells composed of a periodic phononic crystal structure, and a single unit cell includes four resonators A1, which are identical hollow cylinders and arranged in a tetragonal lattice. A positive-negative coupling coupling tube is fixedly connected between the four resonators A1 and between the resonators A1 of adjacent single unit cells. The spacing d between the resonators A1 is 4 mm; the cylinder height h of the resonator A1 is 20 mm, and the radius r is 6 mm.

[0026] The present invention utilizes the reasonable connection mode and size of the coupling tube to realize the positive and negative coupling mechanism of the acoustic wave dipole and introduces the acoustic wave pseudo spin-orbit coupling effect to control the acoustic wave. The introduction of the coupling tube increases the mechanical stability of the overall structure. At the same time, the controllable freedom of the acoustic wave and the stability of the structure are improved. The coupler of the present invention generates a local phonon state density peak at a specific frequency, the regulated acoustic wave has topological characteristics, and the backscattering loss of the acoustic wave is low.

[0027] The number of unit cells of the coupler of the present invention is at least 5, the cylindrical resonator A1 and the coupling tube are made of resin, manufactured by 3D printing technology, filled with air, and have a period of L=28 mm. It can generate local phonon state density peaks at specific frequencies through coupling tubes of different sizes, thereby identifying different sound coding information. The coupler has the advantages of easy preparation and low cost, and the local state of sound is identified only by the size of the coupling tube, so it is flexible to control and easy to operate.

[0028] The entire coupler of the present invention is filled with air, and the boundary is regarded as a hard wall. The overall structure is regarded as a hard wall boundary condition for sound transmission, and the transmission frequency is about 8580 Hz.

[0029] The coupling tube includes four connecting tubes. Two adjacent resonators A1 in the x-axis direction are connected via the first connecting tube C2 and the second connecting tube C1 respectively. Two diagonal resonators A1 in the y-axis direction are connected via the third connecting tube B1 and the fourth connecting tube B2 respectively.

[0030] The first connecting tube C2 is a straight tube set at an angle, and the second connecting tube C1 is a V-shaped bent tube with a certain angle. The inclination angle γ between the first connecting tube C2 and the resonator A1 is 30°, the distance h3 from the end surface close to the resonator A1 is 2mm, and the radius r2 of the first connecting tube C2 is 1mm. The second connecting tube C1 is symmetrically distributed along the midline of the spacing between the two resonators A1, the bending angle α of the second connecting tube C1 is 62°, the distance h2 from the end surface close to the resonator A1 is 2mm, and the radius r1 is 1mm.

[0031] The third connecting tube B1 and the fourth connecting tube B2 have the same size and are symmetrically arranged along the hypotenuse of the tetragonal lattice in the z-axis direction.

[0032] In this embodiment, the third connecting tube B1 and the fourth connecting tube B2 are both V-shaped bends, and the bending directions of the third connecting tube B1 and the fourth connecting tube B2 are opposite, the bending angle β is 92°, the distance h1 from the end surface close to the resonator A1 is 2 mm, and the radius r3 is 0.5 mm.

[0033] Embodiment 2: The difference from the above-mentioned embodiment 1 is that, in this embodiment, the third connecting tube and the fourth connecting tube are straight tubes of the same size and are symmetrically arranged along the hypotenuse of the tetragonal lattice in the z-axis direction; the distance between the third connecting tube and the fourth connecting tube and the end face adjacent to the resonator is 2 mm, and the radius is 0.5 mm.

[0034] Compared with other phononic crystals in the prior art, the present invention introduces a spin-orbit coupling mechanism through the connection method of the coupling tube, thereby improving the controllable freedom of the phononic crystal. Only by changing the size of the coupling tube, a rich acoustic edge state can be obtained. The phononic crystal controllable spin-orbit coupler provided by the present invention is easy to prepare in actual production, with simple materials and low cost. The coupling strength can be modified by changing the size of the coupling tube, the number and position of the phonon state density peaks can be adjusted, and then the specific edge intensity of the sound wave can be controlled by the coupler, achieving flexibility and accuracy in sound wave control. The device regulates the topological characteristics of the sound wave, so the backscattering loss of the sound wave is low, and it has strong robustness.

[0035] There is no upper limit on the length of the spin-orbit coupler of the present invention, and the required length can be set according to the specific use environment. Figure 4 As shown, based on the phononic crystal controllable spin-orbit coupler provided in Example 1, the present invention lists a one-dimensional spin-orbit coupler composed of 14 unit cells, and the sound excitation source 101 needs to be inserted into the structure. It should be emphasized that since the regulation of sound waves by the spin-orbit coupler is based on the principle of sound resonance, in principle the excitation source can be in any position. Marks 102 and 103 in the figure are sound detection sources, and a microphone can be used for the most basic detection, and the detection method is the same as the excitation source detection method. The phononic crystal spin-orbit coupler can be used in acoustic information processing equipment such as acoustic logic gates, acoustic antenna transmission, and acoustic information encoding. It can also be widely used in fields such as sound communication, acoustic information encryption, hydroacoustics, marine exploration, and industrial non-destructive testing, and has high practical value.

[0036] Simulation experiment: Based on the phononic crystal controllable spin-orbit coupler provided in Example 1, the present invention uses the three-dimensional finite element multi-physics field simulation software COMSOL Multiphysics for simulation. During the simulation, a one-dimensional finite-length period phononic crystal array needs to be calculated, and an infinite one-dimensional array is simulated by setting an open boundary in the x direction. Other conditions are hard wall boundary conditions. The sound wave is incident along the x-axis, the grid division is set to be refined, and then the characteristic frequency scan is performed and the sound field distribution result is calculated to obtain the corresponding sound field resonance mode state distribution.

[0037] In order to further illustrate the influence of the spin-orbit coupling effect of the phononic crystal spin-orbit coupler on the distribution and quantity of the localized states of the acoustic field, the present invention simulated the experiment while keeping the other parameters the same, and only changed the size or connection method of the third connecting tube B1 and the fourth connecting tube B2. The simulation results are as follows: Figure 5 The sound field distribution of the characteristic frequency obtained after the structural phononic crystal spin-orbit coupler is excited by the sound wave and the normalized sound intensity amplitude curve related to the spatial position. The results shown are the distribution when the topological mode is (1,0). It can be clearly seen that in the (1,0) topological mode, the sound field can be localized on the left at 8586.5Hz and on the right at 8585.2Hz. The relationship between the normalized intensity amplitude curve and the position shows the localized nature of the sound field from the side. Not only that, on the side away from the edge, a sound field intensity of basically 0 can be observed, indicating that the spin-orbit coupler of the present invention has obvious low backscattering and topological properties.

[0038] Figure 6The acoustic field mode state distributions (a), (b), (c) and (d) of the four topological mode characteristic frequencies of the phononic crystal spin-orbit coupler of the present invention are obtained after acoustic wave excitation. The results show that the acoustic field distribution of the phononic crystal controllable spin-orbit coupler is localized at the boundary in the range of 8575 Hz - 8590 Hz, and has four modes, namely (0,0), (1,0), (0,1), (1,1); and the edge states of the two acoustic fields (1,0) and (0,1) correspond to different positions. The acoustic field distribution also shows topological characteristics, so the backscattering and loss of the field distribution are low, and it is robust. Therefore, by changing the appropriate connection mode and size of the third connecting tube B1 and the fourth connecting tube B2, a rich acoustic field topological protection state can be achieved in the range of 8575 Hz - 8590 Hz. By integrating different structures, the present invention can design acoustic field distributions under different structures, thereby combining acoustic field distributions in different states to achieve the purpose of transmitting information, information encryption, etc.

[0039] Obviously, the embodiments described above are only some embodiments of the present application, rather than all embodiments. The preferred embodiments of the present application are given in the accompanying drawings, but they do not limit the patent scope of the present application. The present application can be implemented in many different forms. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive. Although the present application is described in detail with reference to the aforementioned embodiments, for those skilled in the art, it is still possible to modify the technical solutions recorded in the aforementioned specific implementation methods, or to perform equivalent replacement of some of the technical features therein. Any equivalent structure made using the contents of the specification and drawings of this application, directly or indirectly used in other related technical fields, is similarly within the scope of patent protection of this application.

Claims

1. A phononic crystal controllable spin-orbit coupler for acoustic wave control, characterized in that: It comprises a plurality of unit cells formed by a periodic phononic crystal structure, wherein a single unit cell comprises four resonators, which are identical hollow cylinders and arranged in a tetragonal lattice; coupling tubes for positive and negative coupling are fixedly connected between the four resonators and between the resonators of adjacent unit cells.

2. The phononic crystal controllable spin-orbit coupler for acoustic wave control according to claim 1, characterized in that: The number of the unit cells is at least 5, and the material is resin material.

3. The phononic crystal controllable spin-orbit coupler for acoustic wave control according to claim 1, characterized in that: The spacing between the resonators is 4 mm; the cylindrical height of the resonator is 20 mm and the radius is 6 mm.

4. The phononic crystal controllable spin-orbit coupler for acoustic wave control according to claim 1, characterized in that: The coupling tube includes four connecting tubes. Two adjacent resonators in the x-axis direction are connected via a first connecting tube and a second connecting tube respectively. Two diagonal resonators in the y-axis direction are connected via a third connecting tube and a fourth connecting tube respectively.

5. The phononic crystal controllable spin-orbit coupler for acoustic wave control according to claim 4, characterized in that: The first connecting pipe is a straight pipe arranged obliquely, and the second connecting pipe is a V-shaped bent pipe with a certain angle.

6. The phononic crystal controllable spin-orbit coupler for acoustic wave control according to claim 5, characterized in that: The inclination angle between the first connecting tube and the resonator is 30°, the distance from the end surface adjacent to the resonator is 2 mm, and the radius of the first connecting tube is 1 mm.

7. The phononic crystal controllable spin-orbit coupler for acoustic wave control according to claim 5, characterized in that: The second connecting tube is symmetrically distributed along the midline of the interval between the two resonators. The bending angle of the second connecting tube is 62°, the distance from the end surface adjacent to the resonator is 2 mm, and the radius is 1 mm.

8. The phononic crystal controllable spin-orbit coupler for acoustic wave control according to claim 4, characterized in that: The third connecting tube and the fourth connecting tube have the same size and are symmetrically arranged along the hypotenuse of the tetragonal lattice in the z-axis direction.

9. The phononic crystal controllable spin-orbit coupler for acoustic wave control according to claim 8, characterized in that: The third connecting tube and the fourth connecting tube are V-shaped bent tubes, the bending directions of the third connecting tube and the fourth connecting tube are opposite, the bending angle is 92°, the distance from the end surface close to the resonator is 2 mm, and the radius is 0.5 mm.

10. The phononic crystal controllable spin-orbit coupler for acoustic wave control according to claim 8, characterized in that: The third connecting tube and the fourth connecting tube are straight tubes, the distance from the end surface close to the resonator is 2 mm, and the radius is 0.5 mm.

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