A multi-port waveguide structure based broadband subwavelength acoustic trigger

Abstract

The application discloses a kind of wideband subwavelength acoustic trigger based on multi-port waveguide structure, belong to the field of acoustic metamaterials.It includes two phased units, each phased unit is composed of an open tunnel, two rows of small baffles are arranged in the tunnel upper and lower sides with oppositely arranged angle symmetry, the number of each row of small baffles is greater than or equal to ten;Two phased units have a spacer;The outlet of two phased units is provided with a section of circular arc type waveguide, and is communicated with the outlet of acoustic trigger, and forms a resonance area at the connection;The outlet of acoustic trigger is oppositely arranged with the spacer, and the width of outlet is the same with the width of inlet.The acoustic trigger of the application has a uniform threshold and wideband, compared with traditional acoustic logic device, the structure is simpler, the size is smaller, the phase of outgoing sound wave is passively regulated by using two phased units to realize interference enhancement and interference cancellation, and different logic functions are realized.

Description

Technical Field

[0001] This invention belongs to the field of acoustic metamaterials, and particularly relates to a broadband subwavelength acoustic trigger based on a multi-port waveguide structure. Background Technology

[0002] Sound waves are common information and energy carriers in daily life. Compared with light waves and electromagnetic waves, sound waves are unaffected by electromagnetic fields, offering better stability and security. Utilizing sound waves for information processing and logical calculations can provide fundamental components for future acoustic communications that are resistant to electromagnetic interference and highly secure. Research on acoustic triggers has significant academic value and application prospects. If acoustic triggers are successfully implemented, they can be applied to various important applications requiring specific control of sound energy, such as acoustic computing, acoustic encryption, and acoustic recognition.

[0003] Currently, researchers both domestically and internationally mainly implement the functions of acoustic logic devices based on two mechanisms: nonlinearity and linear coherence.

[0004] (1) Regarding nonlinear mechanisms, acoustic logic functions such as acoustic switches, AND gates, and OR gates can be realized by using spherical particles driven by nonlinear contact forces and combining them with a selection mechanism of acoustic wave frequency bandgap. When an acoustic wave of a specific frequency is incident on a continuously driven spherical chain, the incident acoustic wave interacts with the nonlinear acoustic wave generated by the driving spherical chain, thereby changing the frequency of the acoustic wave. By adjusting the frequency of the nonlinear acoustic wave, the incident evanescent wave, which was originally in the bandgap of the spherical chain, can be converted into a propagating wave. Through the spherical chain, an acoustic switch can be designed and implemented. On this basis, acoustic logic AND gates and OR gates can also be realized using incident signals of two frequencies.

[0005] (2) Regarding the linear coherence mechanism, a logic gate device with basic functions was proposed based on the self-collimated acoustic beam in a two-dimensional phononic crystal and utilizing the linear interference between two input signals. When only one acoustic wave is incident on the phononic crystal, half of the energy is reflected, and the other half is emitted along the original direction. When two acoustic waves are incident simultaneously with an incident phase difference of π / 2, the reflected wave and the refracted wave undergo coherent enhancement and coherent cancellation, thereby realizing the function of an acoustic trigger. In addition, based on the properties of near-zero refractive index acoustic metamaterials, researchers have implemented acoustic logic AND gates, OR gates, NOT gates, and complex logic functions by designing a coiled spatial structure.

[0006] (3) Acoustic logic functions can also be realized using a multi-port circular waveguide structure. Based on the linear acoustic coherence mechanism, the acoustic pressure amplitude and phase difference of the two input signals are actively controlled to realize basic acoustic logic functions such as AND gate, OR gate, and NOT gate.

[0007] The disadvantages of traditional technology are :

[0008] (1) The operating frequency of acoustic waves in acoustic logic devices designed based on nonlinear mechanisms will change.

[0009] (2) Logic devices based on near-zero refractive index acoustic metamaterials have complex structures and narrow operating bandwidths, or even a single frequency.

[0010] (3) Logic devices based on phononic crystal design are large in size and have inconsistent threshold values;

[0011] (4) In the existing acoustic logic devices, only the logic function of general logic gates is implemented, and the logic function of flip-flops is not implemented.

[0012] The reasons for the defects of traditional technologies include :

[0013] (1) Sound waves drive the chain through spherical particles. Based on nonlinear mechanism and bandgap selection mechanism, the incident sound waves will interact with nonlinear sound waves, causing the sound wave frequency to change. Moreover, the sound waves only have two states: transparent and opaque, resulting in a single sound logic function.

[0014] (2) Near-zero refractive index acoustic metamaterials are mainly composed of complex coiled spatial structures, and the near-zero refractive index characteristics originate from the FP resonance of the unit, which leads to the complex structure and narrow operating bandwidth of the designed logic devices.

[0015] (3) Simple acoustic logic functions can be realized based on the linear interference of self-collimated beams in a two-dimensional phononic crystal. However, phononic crystals require a certain period to generate directional bandgap characteristics, which inevitably leads to a large size of the linear system. In addition, the realization of various acoustic logic functions requires setting different thresholds;

[0016] (4) Traditional acoustic logic devices often change the transmission state of sound waves by changing the phase, but the state can be controlled by the linear coherence mechanism of sound waves and the transmittance of the unit at the same time. Summary of the Invention

[0017] The purpose of this invention is to address the technical challenges of traditional acoustic logic devices, such as inconsistent threshold values, narrow operating bandwidth, single logic function, large device size, complex structure, and difficulty in integration. It proposes an acoustic trigger with unified threshold values, wide operating bandwidth, multiple logic functions, and a subwavelength miniaturized structure.

[0018] The present invention achieves the above-mentioned technical objectives through the following technical means.

[0019] A broadband subwavelength acoustic trigger based on a multi-port waveguide structure includes two phased-array units: a first phased-array unit and a second phased-array unit. Each phased-array unit consists of an open tunnel with two rows of small baffles symmetrically arranged at opposite angles on the upper and lower sides of the tunnel. The number of small baffles in each row is greater than or equal to ten. A partition is provided between the two phased-array units. An arc-shaped waveguide is provided at the outlet of each phased-array unit and is connected to the outlet of the acoustic trigger, forming a resonant region at the connection. The outlet of the acoustic trigger is opposite to the partition, and the width of the outlet is the same as the width of the inlet.

[0020] Furthermore, the structural parameters of the small baffle in the first phased array unit are as follows: the width of the small baffle is 0.005λ≤w≤0.006λ, the length is a=0.045λ, the number of baffles in each row is 10≤n≤12, and the rotation angle is 15°≤θ≤19°; the structural parameters of the small baffle in the second phased array unit are as follows: the width of the small baffle is 0.005λ≤w≤0.006λ, the length is 0.045λ, the number of baffles in each row is 10≤n≤12, and the rotation angle is 55°≤θ≤62°; the length of the tunnel is l=0.5λ; the length of the resonant region is 0.07λ≤d1≤0.1λ; where λ is the wavelength of the incident sound wave.

[0021] An acoustic trigger, improved based on the above-mentioned trigger structure.

[0022] Furthermore, the partition is replaced by a third phase control unit, which is a cavity with an independent entrance. Inside, there are two rows of small baffles arranged opposite each other, and the number of small baffles in each row is greater than or equal to ten. The outlet of the third phase control unit is connected to the resonant region.

[0023] Furthermore, the structural parameters of the small baffle in the third phase control unit are as follows: the width of the small baffle is 0.014λ≤w≤0.017λ, the length is a=0.045λ, the number of baffles in each row is 10≤n≤12, and the rotation angle is 50°≤θ≤56°; the length of the tunnel is l=0.5λ; the width of the third phase control unit is h=d=0.1λ; and the length of the resonant region is 0.07λ≤d1≤0.1λ.

[0024] Furthermore, the material of the acoustic trigger is one of the following: plexiglass, plastic, or metal.

[0025] Furthermore, the acoustic trigger is fabricated using 3D printing technology.

[0026] Furthermore, the number of symmetrical small baffles in each phase control unit can be 10, 11, or 12.

[0027] The beneficial effects of this invention are:

[0028] (1) The acoustic trigger has a uniform threshold and wide bandwidth characteristics.

[0029] The acoustic triggers proposed in this invention all achieve acoustic logic functions at a threshold of 10dB. Furthermore, these triggers have a wide operating bandwidth: the T trigger has a bandwidth of 776Hz with a bandwidth ratio of approximately 0.23; the D trigger has a bandwidth of 738Hz with a bandwidth ratio of approximately 0.22.

[0030] (2) The acoustic trigger has a simpler structure and a smaller size.

[0031] Traditional acoustic logic devices are large in size, complex in structure, and difficult to fabricate. The acoustic trigger proposed in this invention has a subwavelength size (length 0.82λ, width 0.32λ), a simple structure, is easy to fabricate and integrate, and is conducive to widespread application.

[0032] (3) Acoustic trigger structure passively controls acoustic signals.

[0033] The acoustic trigger proposed in this invention differs from previous active modulation of incident sound source signals. Based on a linear coherence mechanism, it uses two phase control units to passively modulate the phase of the emitted sound wave to achieve interference enhancement and interference cancellation, thereby realizing different logical functions. It is simple to operate and facilitates program control. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the T-flip-flop structure described in this invention.

[0035] Figure 2 This is a schematic diagram of the D flip-flop structure described in this invention.

[0036] Figure 3 For different input states, the spatial distribution of sound pressure amplitude corresponding to (a) the T trigger and (b) the Q trigger. n+1 The output energy level at the end.

[0037] Figure 4 For different input states, the spatial distribution of sound pressure amplitude corresponding to (a) a D trigger and (b) Q n+1 The output energy level at the end.

[0038] Figure 5 The operating frequency bands of the sound triggers are: (a) T trigger, (b) D trigger. Detailed Implementation

[0039] 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.

[0040] The trigger described in this invention is a three-port waveguide structure composed of a rectangular rigid solid and two phased-array units. The two phased-array units are a first phased-array unit and a second phased-array unit. Each phased-array unit is a cavity with an independent entrance, and each cavity has two rows of small baffles symmetrically arranged at opposite angles on the upper and lower sides of the tunnel. Each row has at least ten small baffles. A partition layer separates the two phased-array units. An arc-shaped waveguide is provided at the exit of each phased-array unit and is connected to the exit of the acoustic trigger, forming a resonant region at the connection point. The exit of the acoustic trigger is opposite to the partition layer, and the width of the exit is the same as the width of the entrance. The acoustic trigger is made of one of the following materials: plexiglass, plastic, or metal, such as epoxy resin, iron, aluminum, or copper.

[0041] Example 1:

[0042] like Figure 1 In the illustrated embodiment, the two phase control units in the acoustic trigger have different structural parameters, enabling the implementation of the logic function of a T trigger. Specifically, the structural parameters of each small baffle in the first phase control unit are: the width of the small baffle is w = 0.005λ, the length is a = 0.045λ, and the rotation angle is θ = 19°; the structural parameters of each small baffle in the second phase control unit are: the width of the small baffle is w = 0.005λ, the length is a = 0.045λ, and the rotation angle is θ = 57°; the length of the tunnel is l = 0.5λ; the length of the resonant region is d1 = 0.075λ; where λ is the wavelength of the incident sound wave.

[0043] To determine the output state, we simulated the sound energy level at the output end using ambient sound as a reference. Here, we chose a uniform threshold of 10dB. When the sound energy level is greater than 10dB, the output state is "1"; when the sound energy level is less than 10dB, the output state is "0".

[0044] The phase difference between the output sound waves in the first phase control unit and the second phase control unit is π; Figure 3 For different input states, the spatial distribution of sound pressure amplitude and output Q generated by the sound trigger described in this embodiment are as follows: n+1 The sound pressure amplitude at the terminal is used to implement the logic function of a T-flip-flop. For example... Figure 3 As shown in (a), when two sound waves with the same initial phase and amplitude are simultaneously incident on ports T and Q... n That is, when the input logic value is (1,1), based on the linear acoustic coherence mechanism, the sound energy level at the output end is lower than the threshold, and the corresponding output logic value is (0); when only one beam of sound wave is incident on port T or Q n That is, when the input logic value is (1,0) or (0,1), the sound energy level at the output terminal is higher than the threshold, and the corresponding output logic value is (1); when no sound wave is incident on ports T and Qn That is, when the input logic value is (0,0), the output sound energy level is lower than the threshold, and the corresponding output logic value is (0). Therefore, the correspondence between the input signal and the output signal is as follows: Figure 3 (b) shows the truth table of the T flip-flop logic, thus realizing the logic function of the T flip-flop.

[0045] Example 2:

[0046] like Figure 2 As shown, the D flip-flop in this embodiment is an improvement on the T flip-flop in Embodiment 1. By replacing the partition in the acoustic flip-flop in Embodiment 1 with a third phase control unit, the logic function of the D flip-flop can be realized. The third phase control unit is a cavity with an independent entrance, and each cavity has two rows of small baffles arranged opposite each other. The number of small baffles in each row is greater than or equal to ten. The outlet of the third phase control unit is connected to the resonant region.

[0047] The width of the small baffle in the third phase control unit is 0.015λ, the length is a = 0.045λ, the number of baffles in each row is 10, and the rotation angle is θ = 52°; the length of the tunnel is l = 0.5λ; the width of the third phase control unit is h = d = 0.1λ; the length of the resonant region is d1 = 0.075λ; the structural parameters of the first phase control unit are the same as those of the second phase control unit and the one in Embodiment 1.

[0048] The phase difference between the sound waves output from the third phase control unit and the first phase control unit is 4π / 5, and the phase difference between the sound waves output from the second phase control unit and the first phase control unit is π / 5. Figure 4 For different input states, the spatial distribution of sound pressure and Q generated by the sound trigger described in this embodiment are as follows: n+1 The sound pressure amplitude at the terminal is used to implement the logic function of the D flip-flop, where port A is set as the control port for a constant acoustic signal with incident sound waves. For example... Figure 4 As shown in (a), when two sound waves are simultaneously incident on port D and port Q... n When the input logic value is (1,1), the sound energy level at the output terminal is higher than the threshold, and the corresponding output logic value is (1); when only one sound wave is incident on port D, that is, when the input logic value is (1,0), the sound energy level at the output terminal is lower than the threshold, and the corresponding output logic value is (0); when only one sound wave is incident on port Q... n That is, when the input logic value is (0,1), the sound energy level at the output is higher than the threshold, and the corresponding output logic value is (1); when no sound wave is incident on ports D and Q n That is, when the input logic value is (0,0), the corresponding output logic value is (0). Therefore, the correspondence between the input signal and the output signal is as follows: Figure 4 (b) shows the truth table of the D flip-flop logic, thus realizing the logic function of the D flip-flop.

[0049] Figure 5 These are the acoustic energy level spectra at the output terminals of the T-flip-flop and D-flip-flop under different input states. Figure 5 (a) It can be seen that in the frequency range of 3293Hz-4069Hz, the T flip-flop can realize the corresponding logic function, with a working bandwidth of up to 776Hz and a bandwidth ratio of about 0.23; further, in the frequency range of 3400Hz-4138Hz, the D flip-flop can realize the corresponding logic function, with a working bandwidth of up to 738Hz and a bandwidth ratio of about 0.22.

[0050] The embodiments described above are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A multi-port waveguide structure based broadband subwavelength acoustic trigger, characterized in that, The sound trigger comprises two phase control units, i.e., a first phase control unit and a second phase control unit, each of which is composed of an open tunnel, and each of which has two rows of small baffles symmetrically arranged on the upper and lower sides of the tunnel at a relative setting angle, and the number of small baffles in each row is greater than or equal to ten; the two phase control units have a partition layer; the outlets of the two phase control units are each provided with a circular arc type waveguide, and are connected with the outlet of the sound trigger, and form a resonance area at the connection; the outlet of the sound trigger is arranged opposite to the partition layer, and the width of the outlet is the same as the width of the inlet. The structural parameters of the small baffles in the first phase control unit are as follows: the width of the small baffles is 0.005λ≤w≤0.006λ, the length is a=0.045λ, the number of each row is 10≤n≤12, and the rotation angle is 15°≤θ≤19°; the structural parameters of the small baffles in the second phase control unit are as follows: the width of the small baffles is 0.005λ≤w≤0.006λ, the length is 0.045λ, the number of each row is 10≤n≤12, and the rotation angle is 55°≤θ≤62°; the length of the tunnel is l=0.5λ; the length of the resonance area is 0.07λ≤d1≤0.1λ; and λ is the wavelength of the incident sound wave.

2. The acoustic trigger of claim 1, wherein, The partition layer is replaced by a third phase control unit, which is a cavity with an independent inlet, and the cavity has two rows of small baffles arranged opposite to each other, and the number of small baffles in each row is 10 or 11 or 12; the outlet of the third phase control unit is communicated with the resonance area.

3. The acoustic trigger of claim 2, wherein, The structural parameters of the small baffles in the third phase control unit are as follows: the width of the small baffles is 0.014λ≤w≤0.017λ, the length is a=0.045λ, the number of each row is 10≤n≤12, and the rotation angle is 50°≤θ≤56°; the length of the tunnel is l=0.5λ; the width of the third phase control unit is h=0.1λ; the length of the resonance area is 0.07λ≤d1≤0.1λ; and λ is the wavelength of the incident sound wave.

4. The acoustic trigger of any one of claims 1-3, wherein, The material of the sound trigger is one of machine glass, plastic and metal material.

5. The acoustic trigger of any one of claims 1-3, wherein, The sound trigger is prepared by 3D printing technology.

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