A subwavelength topological acoustic rainbow trapping device

Abstract

The application discloses a kind of subwavelength topology acoustic rainbow trapping devices.The acoustic rainbow trapping device is composed of topological phononic crystal and sound-absorbing sponge, and the sound-absorbing sponge is distributed around the peripheral boundary of the topological phononic crystal.The topological phononic crystal is composed of periodically arranged acoustic coupling cavity waveguide array, and is divided into topological phononic crystal I without introducing translation deformation to upper and lower cavities, topological phononic crystal II with introducing one-way translation deformation, and topological phononic crystal III with introducing two-way translation deformation.The acoustic wave is incident from the side of the interface formed by topological phononic crystal I and topological phononic crystal II, and can be localized at different angular cavities in the topological phononic crystal III array with frequency change, to realize subwavelength topology acoustic rainbow trapping.The application utilizes the property that the angular state degeneracy is broken and frequency shift occurs after introducing translation deformation, to realize the topology acoustic rainbow trapping that acoustic energy spatial selectivity is localized in subwavelength scale region with frequency change, which can be widely applied in acoustic energy collection, enhanced sensing, filtering and the like.

Description

Technical Field

[0001] This invention belongs to the field of acoustic energy capture technology and relates to a subwavelength topological acoustic rainbow capture device. Technical Background

[0002] Rainbow capture, which can capture waves of different frequencies at different locations in space, has attracted extensive research due to its flexible and adjustable local energy location. Applications such as wavelength division multiplexing (WDM), frequency routing, wave switching, and energy harvesting have emerged based on rainbow capture, potentially promoting the development of acoustic communication systems. Most research on rainbow capture in the acoustic field is based on traditional phononic crystal designs, which are typically complex in structure. Rainbow capture occurs along the structural interface, resulting in a dispersed local acoustic energy range and susceptibility to random interference. Meanwhile, with the development of acoustic topological insulators, topological phononic crystals are also being considered for designing rainbow capture devices to improve their robustness against defects. However, most related research is limited to rainbow capture at one-dimensional interfaces; rainbow capture based on lower-dimensional topological interface states remains to be explored. Summary of the Invention

[0003] The technical problem to be solved by this invention is to address the shortcomings of existing traditional phonon crystal methods and one-dimensional boundary topological rainbow capture, and to propose a subwavelength topological acoustic rainbow capture device, which is used to more accurately localize sound waves of different frequencies to different subwavelength scale regions. Since the designed acoustic rainbow capture device has the characteristics of strong robustness, small local range, high quality factor and small modulus, it can be widely used in sound energy harvesting, enhanced sensing, filtering and other applications.

[0004] To achieve the above-mentioned objectives, the technical solution of this invention is as follows:

[0005] A subwavelength topological acoustic rainbow capturing device is disclosed, comprising a topological phononic crystal and sound-absorbing sponge. The sound-absorbing sponge is distributed around the outer boundary of the topological phononic crystal. The topological phononic crystal is divided into a topological phononic crystal I without introducing translational deformation to the upper and lower cavities, a topological phononic crystal II with unidirectional translational deformation, and a topological phononic crystal III with bidirectional translational deformation. The topological phononic crystal I surrounds four topological phononic crystals III with gradually changing translational deformation. The front and rear boundaries of the topological phononic crystal I are connected to the topological phononic crystal II.

[0006] Furthermore, the topological phononic crystal is composed of an acoustic coupling cavity waveguide array formed by connecting identical cavities vertically in a thin cuboid waveguide layer, and the upper and lower cavities are translated to introduce translational deformation degrees of freedom.

[0007] Furthermore, the interface formed by the topological phononic crystal I and the topological phononic crystal II serves as a dual-channel acoustic energy transmission mechanism for exciting topological acoustic rainbow capture based on the angular states in the topological phononic crystal III.

[0008] Furthermore, the upper and lower boundaries of the topological phonon crystal are both made of 3D-printed epoxy resin material.

[0009] Furthermore, the topological phonon crystal has a lattice constant of a = 5 cm and is composed of an acoustic coupling cavity waveguide array formed by connecting cavities with a height of (aa / 4) / 2 and a length and width of a / 2 in a relatively thin cuboid waveguide layer. The upper and lower cavities are translated to introduce translational deformation degrees of freedom.

[0010] Furthermore, the non-zero Chern number of the topological phononic crystal in space ensures the appearance of topologically protected interface states.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] Compared with the rainbow capture in traditional phononic crystals, the topological acoustic rainbow capture device proposed in this invention has the advantage of simpler structural design. By introducing translational deformation as an additional degree of freedom to control the topological interface state, the acoustic energy can be selectively localized to the subwavelength scale region. It has the characteristics of stronger robustness, smaller local range, and stronger local effect, and can be widely used in acoustic energy harvesting, enhanced sensing, filtering, etc. Attached Figure Description

[0013] Figure 1(a) is a two-dimensional top view of the topological acoustic rainbow capture device of the present invention, showing the gradual change in translational deformation of the four topological phononic crystal III regions. Details of the dashed box region are shown in Figure 1(b). Figure 1(b) is an enlarged view of the dashed box region of Figure 1(a), and a three-dimensional view of the primary unit cells constituting the phononic crystals and their geometric parameters. 1 is phononic crystal I, 2 is phononic crystal II, 3 is phononic crystal III, 4 is the acoustic transmission channel used to excite acoustic rainbow capture based on topological angular states, and 5 is the sound-absorbing sponge.

[0014] Figure 2 In the diagram, (a) represents the bidirectional translational deformation (Δ) introduced into the phononic crystal. x ,Δ y (a) shows the detailed process; (b) shows the corresponding dispersion curve.

[0015] Figure 3 (a) is a schematic diagram of a loop-shaped phononic crystal structure realizing topological angular states. The outer layer consists of topological phononic crystal I, and the inner layer is topological phononic crystal III. Here, Δ x =Δ y=Δ; (b) shows the change in the intrinsic spectrum of the loop structure as the deformation Δ changes; (c) shows the acoustic intensity distribution of the four angular states when degeneracy is broken in the topological phononic crystal III when Δ = 0.46a.

[0016] Figure 4 The image shows the peak sound intensity obtained from the cavity experiments at corners C1 to C7 as marked in Figure 1(a). Detailed Implementation Plan

[0017] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0018] The present invention provides a subwavelength topological acoustic rainbow capturing device, which consists of a topological phonon crystal and a sound-absorbing sponge.

[0019] The sound-absorbing sponge is distributed around the outer boundary of the topological phononic crystal. The sound-absorbing sponge is arranged around the structure to avoid interference from reflected sound waves.

[0020] The topological phononic crystal is composed of an acoustically coupled cavity waveguide array formed by connecting identical cavities vertically within a thin cuboid waveguide layer, with translational deformation degrees of freedom introduced by translating the upper and lower cavities. The topological phononic crystal is divided into three types: Topological Phononic Crystal I (without translational deformation of the upper and lower cavities), Topological Phononic Crystal II (with unidirectional translational deformation), and Topological Phononic Crystal III (with bidirectional translational deformation). The non-zero Chern number of the synthesis space ensures the appearance of topologically protected interface states. The structure consists of Topological Phononic Crystal I enclosing four Topological Phononic Crystal III regions with gradually varying translational deformations, and the front and rear boundaries of Topological Phononic Crystal I are connected to Topological Phononic Crystal II. The front and rear interfaces formed by Topological Phononic Crystal I and Topological Phononic Crystal II serve as a dual-channel acoustic energy transmission mechanism for excitation based on topological acoustic rainbow capture of angular states in Topological Phononic Crystal III.

[0021] Sound waves are incident from one side of the interface between topological phononic crystal I and topological phononic crystal II, and can be localized at different angular cavities in the topological phononic crystal III array as the frequency changes, achieving subwavelength topological acoustic rainbow capture. This invention utilizes the property that the angular degeneracy is broken and frequency shift occurs after introducing translational deformation, achieving topological acoustic rainbow capture where sound energy is spatially selectively localized in the subwavelength scale region as the frequency changes. It can be widely applied to sound energy harvesting, enhanced sensing, filtering, etc.

[0022] Specifically, the topological phononic crystal has a lattice constant of a = 5 cm and is composed of an acoustic coupling cavity waveguide array formed by connecting cavities with a height of (aa / 4) / 2 and a length and width of a / 2 in a relatively thin cuboid waveguide layer. The upper and lower cavities are translated to introduce translational deformation degrees of freedom.

[0023] Specifically, the aforementioned topological phononic crystal is divided into topological phononic crystal I, which does not introduce translational deformation into the upper and lower cavities, and topological phononic crystal II, which introduces unidirectional translational deformation Δ. y The topological phonon crystal II, and the introduction of bidirectional translational deformation (Δ x ,Δ y The topological phonon crystal Ⅲ has a non-zero Chern number in the synthesis space that guarantees the appearance of topologically protected interface states.

[0024] In the following embodiment, the upper and lower interfaces of the coupled cavity waveguide array of the topological phononic crystal are both made of 3D-printed epoxy resin material.

[0025] Referring to Figures 1(a) and 1(b), the upper and lower interface plates of the coupled cavity waveguide topological phononic crystal are first fabricated using 3D printing technology. The dimensions of the upper and lower plates (thickness 0.3cm) are: 120cm long and 60cm wide. The intermediate layer is supported by multiple cuboid scattering pillars, each 1.25cm high and 0.5cm long and wide. The structure consists of four topological phononic crystal regions III surrounding a topological phononic crystal I. The four regions have Δ... x =Δ y = Δ from left to right are Δ = 0.46a, Δ = 0.47a, Δ = 0.48a, and Δ = 0.49a, respectively. The translational deformation of all elements in each region of the topological phononic crystal III is the same. Furthermore, the front and rear boundaries of the topological phononic crystal I are connected to the topological phononic crystal II, with the front phononic crystal II exhibiting a unidirectional translational deformation Δ. y =0.4a, unidirectional translational deformation Δ of the rear phonon crystal II y =0.6a, thus enabling the topological boundary state frequency at the boundary to cover the entire angular state frequency domain, facilitating the capture of topological acoustic rainbows based on the angular states in the topological phonon crystal III through dual-channel excitation. Next, sound-absorbing sponges will be arranged around the perimeter to avoid interference from reflected sound waves.

[0026] The topological phonon crystals I to III have the same lattice constant a = 5 cm.

[0027] Referring to the left inset of Figure 1(b), the topological phononic crystal consists of an air layer sandwiched between upper and lower hard boundary layers. It is constructed from an acoustic coupling cavity waveguide array formed by connecting cavities of height (aa / 4) / 2 and length and width a / 2 vertically within a relatively thin cuboid waveguide layer of height a / 4. Translational deformation degrees of freedom are introduced by translating the upper and lower cavities. A unidirectional translational deformation Δ is introduced. y Formation of topological phonon crystal II, and introduction of bidirectional translational deformation (Δ) x ,Δ y The topological phonon crystal III is formed, and the non-zero Chern number of the synthesis space ensures the appearance of topologically protected interface states.

[0028] See Figure 2Apply different translational deformations (Δ) to the upper and lower cavities x ,Δ y The shape of the topological phonon crystal unit cell changes. Its band structure remains unchanged, and the band gap above the first band in the frequency range of 2504Hz to 3684Hz also remains unchanged.

[0029] See Figure 3 The outer layer of the loop structure used to realize the topological angle state consists of a topological phononic crystal I without introducing translational deformation to the upper and lower cavities, while the inner layer is formed by introducing bidirectional translational deformation (Δ). x ,Δ y The topological phonon crystal III is used to control Δ here for ease of structural tuning. x =Δ y =Δ. As the deformation Δ changes, the intrinsic spectrum of the loop structure changes. Dark gray circles represent bulk states, light gray circles represent boundary states, and black shapes represent angular states. Different shapes correspond to acoustic energy localization at different angles of the topological phononic crystal III. It was observed that with the introduction of translational deformation degrees of freedom, the fourfold degeneracy of the angular states is broken. The acoustic intensity distribution diagram of the four angular states where degeneracy is broken is shown in the topological phononic crystal III when Δ = 0.46a.

[0030] See Figure 4 The acoustic rainbow capture device shown in Figure 1(a) was 3D printed using epoxy resin. A point source emitted acoustic wave was applied to the right (left) end of the front (back) boundary of topological phononic crystal I and topological phononic crystal II to perform frequency sweeping. The volume average acoustic intensity of the upper right (lower left) corner cavity in the inner layer encapsulation region of the topological phononic crystal III was experimentally measured, yielding seven peak values, corresponding to the measurement results at corner cavities C1 to C7 marked in Figure 1(a). This verifies that in the dual-channel configuration, as the frequency increases, acoustic energy is captured in opposite directions along the front and back dual-channel directions into nearby subwavelength-scale corner cavities.

[0031] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the invention. Any simple equivalent changes and modifications made in accordance with the claims and description of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A subwavelength topological acoustic rainbow capturing device, characterized in that, The topological acoustic rainbow capture device consists of a topological phononic crystal and sound-absorbing sponge. The sound-absorbing sponge is distributed around the outer boundary of the topological phononic crystal. The topological phononic crystal is divided into a topological phononic crystal I without introducing translational deformation to the upper and lower cavities, a topological phononic crystal II with unidirectional translational deformation, and a topological phononic crystal III with bidirectional translational deformation. The topological phononic crystal I surrounds four topological phononic crystals III with gradually changing translational deformation. The front and rear boundaries of the topological phononic crystal I are connected to the topological phononic crystal II. The topological phononic crystal is composed of an acoustic coupling cavity waveguide array formed by connecting the same cavities vertically in a thin cuboid waveguide layer, and the upper and lower cavities are translated to introduce translational deformation degrees of freedom. The interface formed by the topological phononic crystal I and the topological phononic crystal II serves as a dual-channel acoustic energy transmission for exciting topological acoustic rainbow capture based on the angular state in the topological phononic crystal III.

2. The subwavelength topological acoustic rainbow capturing device according to claim 1, characterized in that, The upper and lower boundaries of the topological phonon crystal are both made of 3D-printed epoxy resin material.

3. The subwavelength topological acoustic rainbow capturing device according to claim 1, characterized in that, The topological phononic crystal has a lattice constant of a = 5 cm and is composed of an acoustic coupling cavity waveguide array formed by connecting cavities with a height of (aa / 4) / 2 and a length and width of a / 2 in a relatively thin cuboid waveguide layer. The upper and lower cavities are translated to introduce translational deformation degrees of freedom.

4. The subwavelength topological acoustic rainbow capturing device according to claim 1, characterized in that, The non-zero Chern number of the topological phononic crystal ensures the appearance of topologically protected interface states.

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