Solid acoustic topological taper connector and wave shaper

Abstract

The application discloses a solid acoustic topology taper connector, comprising a solid acoustic topology insulator, the solid acoustic topology insulator forms at least two different skin depth topology boundary states, and the band gap width of the solid acoustic topology insulator gradually changes along the signal transmission direction.The solid acoustic topology taper connector of the application takes a plate wave phononic crystal as a construction unit, and by designing and skillfully assembling topology boundaries with different mode volumes, the transmission aperture of a solid acoustic wave in the solid acoustic topology taper connector can be switched as required with almost no loss, and a perfect solution is provided for the series / parallel connection of acoustic elements with different sizes; meanwhile, the solid acoustic topology taper connector can be applied to beam shaping, and can convert any irregular or even damaged incidence into desired, regular and rich plane wave output.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of taper connectors, and relates to a solid acoustic topology taper connector and a wave shaper. BACKGROUND

[0002] With the development of future acoustic integrated devices and systems, the number of elements contained therein is increasing, and they realize complex signal transduction, processing, operation and storage functions through series and parallel connection. Efficiently connecting different sizes and functions of elements is crucial. The ideal connection between two elements should not have any reflection, including transmission reflection and port reflection, so that the signal can pass through the elements at 100%. First, reflection will obviously cause the reduction of signal-to-noise ratio and the decline of device performance. At the same time, in a solid acoustic integrated device containing a large number of elements, reflection will significantly increase the crosstalk between irrelevant elements, rapidly deteriorating the performance of the device. Therefore, the ideal connection between different sizes and functions of elements is particularly necessary for the development of large-scale solid acoustic integrated devices. For acoustic devices and systems containing multiple elements, even for future large-scale integrated acoustic circuits, solid acoustic couplers / taper connectors are of great significance. However, the existing schemes are mainly based on the traditional principles of waveguide physical size gradient or refractive index lens, and cannot realize the reflection-free connection between two elements.

[0003] In recent years, topological materials in the field of solid acoustic have opened up new frontiers for the development of analog devices by providing efficient solid acoustic waveguides and rich degrees of freedom. The most representative advantage of topological waveguides is anti-reflection, which can realize low-loss, high-degree-of-freedom transmission of classical waves and immunity to defects. With the development of topological materials, such waveguides have gradually developed from one dimension to two dimensions and even three dimensions in recent years. However, in addition to the waveguide function, topological materials have not yet shown their advantages in realizing lossless connection between analog elements, i.e. constructing ideal couplers / taper connectors. SUMMARY

[0004] The purpose of the application is to provide a solid acoustic topology taper connector. Another purpose of the application is to provide a solid acoustic topology wave shaper.

[0005] Technical solution: The solid acoustic topology taper connector of the application comprises a solid acoustic topology insulator, and the solid acoustic topology insulator forms topological boundary states of at least two different skin depths.

[0006] Further, the band gap width of the solid acoustic topology insulator gradually changes along the signal transmission direction.

[0007] Further, the solid acoustic topological insulator is composed of a plate wave phononic crystal provided with microstructures, the microstructures are holes or columns, and a band gap width of the solid acoustic topological insulator is determined by a lattice symmetry breaking degree of the solid acoustic topological insulator.

[0008] Further, a cross-sectional shape of the microstructure is a Y-shaped structure with three lobes, an included angle between two adjacent lobes is 120°, a relative angle of a pointing direction of the cross-sectional shape of the microstructure and a Γ-K direction of the plate wave phononic crystal is θ, and the θ = ± (0-30) °.

[0009] Further, a lattice symmetry of the plate wave phononic crystal is a triangular lattice, a hexagonal lattice or a tetragonal lattice.

[0010] Further, a lattice constant of the plate wave phononic crystal is 1 μm to 10 mm.

[0011] Further, a skin depth difference of two adjacent solid acoustic topological insulators with different band gap widths is the same.

[0012] Further, a material of the plate wave phononic crystal is one of a CMOS integrated silicon-based material, a piezoelectric crystal material or a metal material.

[0013] Further, the CMOS integrated silicon-based material includes one of Si, SiO2, SiC and SiN, and the piezoelectric crystal material includes one of LiNbO3, LiTaO3, AlN and GaN.

[0014] Another object of the present application is to provide a solid acoustic topological wave shaper composed of the solid acoustic topological taper connector.

[0015] Advantages: Compared with the prior art, the present application has the following remarkable advantages: 1. The solid acoustic topological taper connector of the present application uses a plate wave phononic crystal as a construction unit, and combines topological boundary states with different mode volumes in an adiabatic gradient manner, so as to realize reflection-free aggregation and separation of wideband solid acoustic waves in different transmission apertures, and provides a solution for ideal connection between elements of different sizes.

[0016] 2. The continuous manipulation of the topological boundary mode volume can not only be used to realize 100% topological energy convergence, but also can realize wave front control and beam shaping, realize modulation of transmission wave aperture size and energy distribution, and convert any incident wave into a perfect plane wave. This scheme has wide applicability and can be extended to mechanical materials and devices of different media, sizes and frequencies, provides key basic elements for the development of large-scale integrated acoustic topological circuits, and is expected to be applied to new generation signal processing, sensing and energy collection and many other scenes. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 A schematic diagram of the principle of the present application.

[0018] Figure 2 A schematic diagram of the structure of an embodiment of the present application, including the overall structure (left) and the unit cell structure (right).

[0019] Figure 3 The energy band, energy distribution and energy field (from top to bottom) of the valley protected topological boundary state formed by three valley insulators with θ being ±5°, ±10° and ±30°, respectively.

[0020] Figure 4 A schematic diagram of the structure of a solid-acoustic topological taper connector of the present application.

[0021] Figure 5 A comparison of the energy field distribution of a solid-acoustic topological taper connector (left) and a conventional taper connector (right) with the same working width.

[0022] Figure 6 The energy field distribution (left) and the energy distribution on the median line (right) obtained from experiments of a solid-acoustic topological taper connector of the present application.

[0023] Figure 7 A graph of the energy concentration rate versus frequency.

[0024] Figure 8 The energy field distribution (from top to bottom) after adding 6 vacancy defects, substitutional defects and interstitial defects, respectively, in the core region of a solid-acoustic topological taper connector.

[0025] Figure 9 A schematic diagram of the structure of a solid-acoustic topological wave shaper of the present application.

[0026] Figure 10 The energy field distribution in the device and the energy distribution of the corresponding port output when all transducers outside port 1 (top) or port 2 (bottom) are working; Figure 10 The energy field distribution in the device and the energy distribution of the corresponding port output when half of the transducers outside port 1 (top) or port 2 (bottom) are working.

[0027] Figure 11 The energy field distribution in the device and the phase distribution of the corresponding input and output ports when random transducers outside port 1 (top) or port 2 (bottom) are working. DETAILED DESCRIPTION

[0028] The technical solutions of the present application will be further described below in conjunction with the drawings and specific embodiments.

[0029] As Figure 1As shown, a solid-state acoustic topology tapered connector of the present invention includes a solid-state acoustic topology insulator, wherein the solid-state acoustic topology insulator forms at least two topological boundary states with different skin depths. The topological boundary states with different skin depths are formed by the gradual variation of the bandgap width of the solid-state acoustic topology insulator along the signal transmission direction. The principle is to control the open bandgap width by adjusting the degree of symmetry breaking of the solid-state acoustic topology insulator, combining different solid-state acoustic topology insulators to construct topological boundary states with different skin depths, and then combining the topological boundary states with different skin depths to form a solid-state acoustic topology tapered connector.

[0030] In a specific embodiment, the solid-state acoustic topological insulator is composed of a plate-wave phononic crystal with microstructures. The plate-wave phononic crystal is made of one of the following materials: CMOS integrated silicon-based materials, piezoelectric crystal materials, or metallic materials. The CMOS integrated silicon-based materials include one of Si, SiO2, SiC, and SiN, and the piezoelectric crystal materials include one of LiNbO3, LiTaO3, AlN, and GaN. The microstructures are holes or pillars. The bandgap width of the solid-state acoustic topological insulator is changed by the change in the relative angle between the cross-sectional shape of the microstructure and the Γ-K direction of the plate-wave phononic crystal. Preferably, the skin depth difference between two adjacent solid-state acoustic topological insulators with different bandgap widths is the same. The lattice symmetry of the plate-wave phononic crystal is a triangular, hexagonal, or tetragonal lattice. The lattice constant of the plate-wave phononic crystal is from 1 μm to 10 mm.

[0031] Example 1

[0032] like Figure 2 As shown, a solid acoustic topology tapered connector of this embodiment is formed by a plate wave phononic crystal with a through hole. The lattice symmetry of the through hole is a triangular lattice. The cross-sectional shape of the through hole is a Y-shape with three lobes. The included angle between two adjacent lobes is 120°. The relative angle between the through hole and the Γ-K direction of the phononic crystal is θ, where θ = ±(0~30)°.

[0033] The band structure of this phonon crystal is determined by the relative angle θ between the Y-shaped through-hole and the crystal's Γ-K direction. When θ = mπ / 3 (m is an integer), the phonon crystal exhibits C 3v Symmetry is maintained, and the band structure exhibits Dirac degeneracy at points K (and K'), giving the crystal characteristics of a Dirac half-metal. When θ is at other angles, the symmetry of the phononic crystal decreases to C3. Due to the disruption of mirror symmetry, degeneracy points are opened, forming a band gap, and the crystal forms a valley insulator. Furthermore, the width of the band gap increases with increasing θ (within the range of 0-30°).

[0034] Valley-protected topological boundaries can be constructed by combining two valley insulators with opposite θ values ​​along the Γ-K direction, whose energy bands are as follows: Figure 3Represented. From top to bottom in the figure are valley protection topological boundary states composed of three kinds of valley insulators with θ = ± 30°, ± 10° and ± 5°. Since the size of θ determines the band gap width of the valley insulator, it also determines the bandwidth and mode volume of the boundary state.

[0035] As an application display, a solid acoustic topological tapered connector realized by a topological phononic crystal is designed as shown in the figure, which comprises three main parts, from bottom to top, respectively: a Dirac semimetal region 2, a gradually changing valley insulator region 3 and a non-gradually changing valley insulator region 4; the gradually changing valley insulator region 3 and the non-gradually changing valley insulator region 4 are mutually symmetrical at the center line of the solid acoustic topological tapered connector to form a topological boundary center; wherein: Figure 4

[0036] The Dirac semimetal region 2 is provided with 6 layers of θ = 0° through holes for realizing impedance matching between the phononic crystal-free and phononic crystal regions;

[0037] The gradually changing valley insulator region 3 is provided with 12 layers of through holes with θ values gradually changing from 5° to 30° for realizing complete coupling of a plane wave with a large aperture into a compact acoustic topological waveguide; since the skin depth of the topological boundary state monotonically decreases with the increase of θ, we design the skin depth difference corresponding to the adjacent two layers of gradually changing structures to be consistent. θ from bottom to top is 5.3°, 5.7°, 6.15°, 6.66°, 7.24°, 7.91°, 8.7°, 9.67°, 10.92°, 12.69°, 15.78° and 30°;

[0038] The non-gradually changing valley insulator region 4 is provided with θ = 30° through holes for providing a compact and uniform width acoustic waveguide.

[0039] In a specific embodiment, the thickness of the plate wave phononic crystal h = 3.95mm, the lattice constant a = 10mm. The length of each petal of the through hole r = 4.5mm, the width d = 2.1mm, and the end is rounded.

[0040] The solid acoustic topological tapered connector of the present application is tested. The sample is specially prepared on a polished stainless steel plate (mass density 7900.5kg / m 3 ), and the plate thickness is fixed at 3.95mm. Their elastic parameters are determined by ultrasonic scattering echo method, and the Young's modulus is 203.25GPa and the Poisson's ratio is 0.3328. The holes are opened on a precision numerical control milling machine to prepare a solid acoustic topological tapered connector composed of Y-shaped through holes (the length of each petal of the through hole is 4.5mm, the width is 2.1mm, and the end is rounded). The sample is coated with sound-absorbing glue (epoxy resin, tungsten powder and graphite powder) on the four sides to prevent unnecessary reflection. ​

[0041] Numerical calculation: The acoustic module of the commercial software COMSOL MULTIPHYSICS was used to calculate the band structure of the solid acoustic topological insulator and the acoustic field distribution of the device by the three-dimensional finite element method.

[0042] Experimental setup: The broadband piezoelectric transducers (center frequency of 66 kHz) attached to the side of the sample were used as the acoustic source to excite the plane wave. The signal generator outputted a sinusoidal signal, which was amplified by the power amplifier and used to drive the piezoelectric transducers. We used a laser Doppler vibrometer to measure the amplitude and phase information of the sample surface.

[0043] In the experiment, we placed 11 identical broadband piezoelectric transducers 1 at the lower end of the sample to achieve wide-aperture plane wave excitation and incidence on the solid acoustic topological cone connector. With the help of the laser Doppler vibrometer, we recorded the acoustic field distribution in the entire solid acoustic topological cone connector at different frequencies. To eliminate the adverse effects of solid acoustic wave reflection on the sample edge on the measurement, the entire outer edge of the sample was wrapped with high-performance sound-absorbing materials.

[0044] Figure 5 The transmission effect of the solid acoustic topological cone connector (left) and the traditional cone connector (right) at a working frequency of 66 kHz is shown. The energy at the input end of the two is the same. It can be seen that the solid acoustic topological cone connector can achieve higher transmission efficiency in a shorter transmission distance compared with the traditional cone connector.

[0045] Figure 6 The energy field distribution measured experimentally at a working frequency of 66 kHz is shown. The right inset is the energy distribution on the center line (topological boundary center) of the sample. It can be seen that the sound is significantly spatially concentrated and energy-enhanced when transmitted in the solid acoustic topological cone connector.

[0046] To more intuitively and quantitatively show this topological reflection-free spatial concentration, we measured the energy ratio of the five periods in the back waveguide region and the five periods in the front waveguide region of the solid acoustic topological cone connector at different frequencies, as shown in Figure 7 In the range of 65 kHz-68 kHz, the energy concentration efficiency is more than 95%, which verifies the broadband characteristics of the device (the bandwidth is determined by the valley insulator with the smallest θ).

[0047] This solid acoustic topological cone connector retains the anti-reflection characteristics and broadband characteristics of the solid acoustic topological insulator boundary. The solid acoustic wave input by the wide-aperture port can be completely guided into the compact topological waveguide, providing a key basic element scheme for large-scale integrated topological information processing devices and sensor devices.

[0048] As shown in Figure 8As shown, the solid-state acoustic topological taper connector is protected by the valley topology, so it can still work normally in the presence of defects. We introduce Figure 8 Three kinds of defects of different wavelength scales are shown to verify this topological protection. Figure 8 The energy field distribution measured by experiment after adding 6 vacancy defects, substitution defects and interstitial defects in the core area of the solid-state acoustic topological taper connector from top to bottom, respectively. Among them, the substitution defects use a column with the same shape as the hole to replace the hole position, and the gap "atoms" in the interstitial defects are stainless steel cylinders (diameter 3mm, height 3mm). The experimental working frequency shown in the figure is 66kHz; they all show good defect immunity, which further verifies the robustness and practicality of the device.

[0049] The present application also provides a solid-state acoustic topological wave shaper, which can also be used to control the wave front and beam shaping by continuous manipulation of the topological boundary mode volume, and realize the modulation of the transmission aperture size and energy distribution. In order to show, we designed a solid-state acoustic topological wave shaper as shown. Figure 9 The device is composed of two solid-state acoustic topological taper connectors, including port 1 and port 2, and the band gap width of the solid-state acoustic topological insulator in the two solid-state acoustic topological taper connectors connected together first increases and then decreases from port 1 to port 2.

[0050] In the experiment, we placed 11 consistent broadband piezoelectric transducers on the outside of the upper and lower ports of the device. The sound field distribution in the device when the upper port and lower port transducers work independently was recorded.

[0051] Figure 10 The energy field distribution in the device and the corresponding energy distribution of the port output when all transducers outside port 1 (top) or port 2 (bottom) work; Figure 10 The right graph is the energy field distribution in the device and the corresponding energy distribution of the port output when half of the transducers outside port 1 (top) or port 2 (bottom) work. As can be seen from the figure, when all transducers outside port 1 work, the plane wave enters the device from port 1 first converges and then diffuses, and the plane wave output at port 2 presents a uniform spatial energy distribution. When all transducers outside port 2 work, the plane wave enters the device from port 2 first converges and then diffuses, and the plane wave output at port 1 presents a non-uniform energy distribution with the strongest in the middle and exponential decay on both sides.

[0052] It is worth noting that this solid acoustic topology cone connector and beam shaper does not rely on a specific high-quality plane wave input. For irregular, incomplete plane wave input, the device also has complete similar beam shaping ability. To verify, we experimentally recorded the sound field distribution in the device when only half of the two-port outside transducers and six random transducers were working. The energy distribution at the exit end was almost the same as that when the full plane wave was incident.

[0053] Figure 11 For port 1 (upper) or port 2 (lower) outside random transducer, the energy field distribution in the device and the corresponding input and output port phase distribution. It can be seen that the solid acoustic topology beam shaper can also convert the incident wave with arbitrary energy and phase distribution into a perfect plane wave. When port 1 or port 2 outside the random 6 transducers are working, the energy and phase of the incident wave are relatively chaotic, and after beam shaping, the chaotic incident wave is converted into a perfect plane wave.

[0054] It can be seen that in the beam shaping scheme, the spatial energy distribution of the output plane wave can be customized by designing and assembling different solid acoustic topology cone connectors, and it is suitable for any complex input wave form, showing the practicability and application potential of the solid acoustic topology cone connector in future large-scale topology signal processing lines.

Claims

1. A solid-borne sound topological cone connector, characterized in that, The solid acoustic topological insulator forms topological boundary states of at least two different skin depths, a band gap width of the solid acoustic topological insulator is graded along a signal transmission direction, the solid acoustic topological insulator is composed of a plate wave phononic crystal provided with a microstructure, the microstructure is a hole or a column, and the band gap width of the solid acoustic topological insulator is determined by a degree of lattice symmetry breaking of the solid acoustic topological insulator.

2. The structural solid acoustic topological cone connector of claim 1, wherein, A cross-sectional shape of the microstructure is a Y-shaped structure with three lobes, an included angle between two adjacent lobes is 120°, a relative angle between a pointing direction of the cross-sectional shape of the microstructure and a Γ-K direction of the plate wave phononic crystal is θ, and the θ = ± (0~30)°.

3. The structural solid acoustic topological cone connector of claim 1, wherein, The lattice symmetry of the plate wave phononic crystal is a triangular lattice, a hexagonal lattice or a tetragonal lattice.

4. The structural solid acoustic topological cone connector of claim 1, wherein, A lattice constant of the plate wave phononic crystal is 1 μm to 10 mm.

5. The structural solid acoustic topological cone connector of claim 1, wherein, Skin depths of two adjacent solid acoustic topological insulators with different band gap widths are the same.

6. The structural solid acoustic topological cone connector of claim 1, wherein, The material of the plate wave phononic crystal is one of a CMOS integrated silicon-based material, a piezoelectric crystal material or a metal material.

7. The structural solid acoustic topological cone connector of claim 6, wherein, The CMOS integrated silicon-based material includes one of Si, SiO2, SiC and SiN; and the piezoelectric crystal material includes one of LiNbO3, LiTaO3, AlN and GaN.

8. A solid acoustic topological wave shaper, characterized by, The solid acoustic topological taper connector is combined by the solid acoustic topological insulator in claim 1.

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