Acoustic delay line device

Abstract

The invention relates to an acoustic delay line device, comprising: a substrate; the first transducer and the second transducer are arranged on the surface of the substrate and are respectively distributed on two sides of the substrate; the excitation source is used for applying complex frequency sound waves to the first transducer or the second transducer so as to realize uniform amplitude wave transmission on the acoustic delay line device; the excitation source comprises a plurality of simple harmonic sources used for generating a plurality of real frequency sound waves; and the synthesizer is used for carrying out weighted stacking on the plurality of real-frequency sound waves according to a preset weight to form the complex-frequency sound waves. According to the invention, uniform amplitude transmission of sound waves in the loss medium is realized.

Description

Technical Field

[0001] The invention relates to the technical field of surface acoustic waves, and in particular to an acoustic delay line device. Background Art

[0002] For traditional sound waves, when they propagate in an acoustic delay line device, due to the loss of the transmission medium, the actual sound wave is not an ideal simple harmonic wave with uniform amplitude, but a wave whose amplitude will continuously decay as the transmission distance increases. When the existing acoustic delay line device is applied to Raman-Nesse diffraction, the intensity of each level of diffraction light will change as the transmission distance increases; when the existing acoustic delay line device is applied to stimulated Brillouin scattering, the generated Stokes or anti-Stokes light will have an uneven distribution. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide an acoustic delay line device, which realizes the uniform amplitude transmission of sound waves in a lossy medium.

[0004] The technical solution adopted by the present invention to solve the technical problem is: to provide an acoustic delay line device, comprising:

[0005] substrate;

[0006] A first transducer and a second transducer are arranged on the surface of the substrate and are respectively distributed on two sides of the substrate;

[0007] an excitation source for applying a complex frequency acoustic wave to the first transducer or the second transducer to achieve uniform amplitude wave transmission in the acoustic delay line device;

[0008] The excitation source includes:

[0009] A plurality of simple harmonic wave sources for generating a plurality of real frequency sound waves;

[0010] The synthesizer is used to perform weighted superposition of the plurality of real-frequency sound waves according to preset weights to form the complex-frequency sound wave.

[0011] The amplitude function V of the complex frequency sound wave is expressed as: V=Cexp(-βt), wherein C is a constant, β=αv, α is the Rayleigh damping loss parameter of the substrate, and v represents the sound velocity.

[0012] The real frequency ω corresponding to the displacement field of the i-th real frequency sound wave among the plurality of real frequency sound waves i is the angular frequency of the i-th point after the series expansion of the displacement field integral of the complex frequency sound wave.

[0013] The preset weight of the i-th real frequency sound wave among the plurality of real frequency sound waves is Among them, C(ωi ) is the preset weight of the ith real frequency sound wave, is the angular frequency of the complex frequency sound wave, ω i is the angular frequency of the i-th point after the series expansion of the displacement field integral of the complex frequency sound wave, Δω i is the angular frequency ω of the i-th point after the series expansion of the displacement field integral of the complex frequency sound wave i The angular frequency ω of the i+1th point after series expansion of the displacement field integral of the complex frequency sound wave i+1 The frequency difference between them.

[0014] The substrate is a piezoelectric material; the piezoelectric material includes at least one of lithium niobate and lithium tantalate.

[0015] The substrate is a piezoelectric heterogeneous material.

[0016] The first transducer and the second transducer are both made of metal materials; the metal material includes at least one of aluminum, gold, copper, tungsten, and platinum.

[0017] Beneficial Effects

[0018] Due to the adoption of the above-mentioned technical scheme, the present invention has the following advantages and positive effects compared with the prior art: the present invention adopts real-frequency sound waves generated by multiple simple harmonic wave sources to synthesize equivalent complex-frequency sound waves, thereby realizing virtual gain of the acoustic displacement field, thereby avoiding the influence of transmission loss on the amplitude of the acoustic field, and realizing uniform amplitude transmission of sound waves in lossy media. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic structural diagram of an acoustic delay line device according to an embodiment of the present invention;

[0020] Figure 2 yes Figure 1 A top view of a longitudinal slice;

[0021] Figure 3 yes Figure 1 Side view of longitudinal slice;

[0022] Figure 4 This is a schematic diagram of sound wave transmission under ideal conditions;

[0023] Figure 5 It is a schematic diagram of sound wave transmission in the presence of loss;

[0024] Figure 6 is a schematic diagram of a complex frequency sound wave generated by an excitation source according to an embodiment of the present invention;

[0025] Figure 7 is a schematic diagram of converting the integral form of Fourier expansion into a series form in an embodiment of the present invention;

[0026] Figure 8 It is a schematic diagram of the complex frequency sound wave synthesis principle of an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0028] A first embodiment of the present invention relates to an acoustic delay line device, such as Figure 1 As shown, including:

[0029] Substrate 1: The substrate 1 may be made of piezoelectric material or piezoelectric heterogeneous material. When piezoelectric material is used, it includes at least one of lithium niobate and lithium tantalate. The substrate 1 in this embodiment is a lithium niobate substrate.

[0030] The first transducer 2 and the second transducer 3 are arranged on the surface of the substrate 1 and are respectively distributed on both sides of the substrate 1. The first transducer 2 and the second transducer 3 in this embodiment are both interdigital transducers, which are made of metal materials, wherein the metal material includes at least one of aluminum, gold, copper, tungsten, and platinum. The first transducer 2 and the second transducer 3 in this embodiment are both made of metal aluminum.

[0031] An excitation source (not shown in the figure) is used to apply a complex frequency sound wave to the first transducer or the second transducer to achieve uniform amplitude wave transmission in the acoustic delay line device; the excitation source includes: a plurality of simple harmonic wave sources, used to generate a plurality of real frequency sound waves; a synthesizer, used to weightedly superimpose the plurality of real frequency sound waves according to preset weights to form the complex frequency sound wave.

[0032] It can be seen that this embodiment uses real-frequency sound waves generated by multiple simple harmonic wave sources to synthesize equivalent complex-frequency sound waves, thereby achieving virtual gain of the acoustic displacement field, thereby avoiding the influence of transmission loss on the amplitude of the sound field, and achieving uniform amplitude transmission of sound waves in lossy media.

[0033] The principle of this implementation is described below through a specific example.

[0034] For Figure 1 The acoustic delay line device shown in FIG. 1 includes, from left to right, an interdigital transducer (hereinafter referred to as IDT) at the transmitting end and an IDT at the receiving end. Figure 1 The structure shown in Figure 2 is extracted as Figure 2 and Figure 3The longitudinal slice model shown is used to study the acoustic wave on the IDT transmission path (x-axis direction). In this embodiment, the IDT period W_IDT is 3.2μm, the thickness H_IDT is 70nm, the thickness H_LN of the lithium niobate substrate 1 is 500nm, and the thickness H_SIC of the silicon carbide substrate 4 is 6.4μm.

[0035] A simple harmonic electric field is applied to the IDT at the transmitting end. When the substrate is in an ideal condition (i.e., lossless condition), the generated acoustic field is expressed as a traveling wave along the transmission path (x-axis direction) (the expression of its displacement u can be expressed as u=u0exp(iωt-ikx), where ω is the angular frequency of the excitation and k is the wave vector). In this embodiment, an angular frequency excitation of 1.676 GHz is applied, and the acoustic field changes with displacement as shown below Figure 4 The periodic changes shown in the figure. Since piezoelectric materials such as lithium niobate often have damping loss in actual situations, the Rayleigh damping loss parameter α is set to 4×10 8 , then the original traveling wave will appear as Figure 5 The damped vibration form shown in FIG. 1 shows a natural exponential decay in its amplitude envelope. The corresponding displacement expression can be expressed in the general form as follows: u = u0exp(iωt-ikx)exp(-γx), where γ represents the transmission loss of the sound wave along the x-axis direction, and exp(iωt-ikx) represents the time and space phase of the displacement. In this embodiment, Figure 5 In the acoustic displacement expression shown in the figure, ω = 10.53 × 10 9 rad / s, k = 1.669 × 10 6 rad / m,γ=3.27×10 4 m -1 .

[0036] For the amplitude at the x1 position at a certain time t1, it is composed of the product of two parts. One is the loss exp(-γx1) suffered by the sound wave after transmitting the x1 distance, and the other is the amplitude function of the transmitting source corresponding to the x1 position at time t1. Where v is the speed of sound. If a wave with uniform amplitude is generated at time t1, then the amplitude of the sound wave at any position x1 and x2 is the same, that is, The wave source is processed in this way, and the amplitude function of the wave source is set to V = Cexp(-βt), where C is an arbitrary constant and β = αv can meet the requirement of the same amplitude. In this embodiment, β = 2.063 × 10 8 s -1 , using a wave source excitation that satisfies this amplitude function, we can obtain Figure 6 The uniform amplitude wave shown by the black line ( Figure 6 The red line in the middle is the sound wave when the wave source is not processed).

[0037] Combining the above amplitude function and phase function, the sound wave E generated by the excitation source can be expressed as: in, And ω=10.53×10 9 rad / s, β=2.063×10 8 s -1 Since the sound wave has no physical meaning when t approaches negative infinity, truncation is used in, Therefore, the wave source can be regarded as a complex frequency sound wave with a frequency of ω~=ω+iβ. For complex frequency sound waves, there are relatively stringent requirements for time in actual measurement, and the actual inspection of its uniform amplitude transmission characteristics also needs to meet the requirements of time synchronization at different positions. Therefore, the complex frequency sound wave can be equivalent to the synthesis of real frequency sound waves.

[0038] For complex frequency sound waves The corresponding displacement field is Among them, A=u0exp(-ikx)θ(t), and Fourier expansion is performed here to obtain: Discretize it and transform the integral into a series (the principle is as follows Figure 7 As shown) that is: Where u(ω i )=Aexp(iω i t) corresponds to the real frequency ω i The displacement field of the sound wave, the real frequency ω i is the angular frequency of the i-th point after the series expansion of the displacement field integral of the complex frequency sound wave, Δω i is the angular frequency ω of the i-th point after the series expansion of the displacement field integral of the complex frequency sound wave i The angular frequency ω of the i+1th point after series expansion of the displacement field integral of the complex frequency sound wave i+1 The frequency difference between them. Therefore, multiple real frequencies ω are used i The displacement field of the sound wave and the corresponding weight By performing weighted superposition, the displacement field under complex frequency sound waves can be obtained, such as Figure 8 As shown. Therefore, we can use several i The displacement field is measured with a simple harmonic source of sound waves, and then the results are weighted superimposed accordingly to obtain the equivalent complex frequency sound waves.

[0039] The acoustic delay line device of this embodiment can be applied to Raman-Nyss diffraction in actual lossy media. Since the complex frequency sound waves generated by synthesizing real frequency sound waves in this embodiment are simple harmonic waves with uniform amplitude at all times, the change of diffraction light intensity at each level caused by the increase of transmission distance can be avoided. The acoustic delay line device of this embodiment can also be applied to stimulated Brillouin scattering in actual lossy media. Since this embodiment can generate uniform amplitude waves, it will not attenuate with increasing distance, thereby avoiding the uneven distribution of Stokes or anti-Stokes light generated. In addition, the acoustic delay line device of this embodiment breaks the time reversal symmetry, so it can be used to construct acoustic non-reciprocal transmission.

Claims

1. An acoustic delay line device, characterized in that: include: substrate; A first transducer and a second transducer are arranged on the surface of the substrate and are respectively distributed on two sides of the substrate; an excitation source for applying a complex frequency acoustic wave to the first transducer or the second transducer to achieve uniform amplitude wave transmission in the acoustic delay line device; The excitation source includes: A plurality of simple harmonic wave sources for generating a plurality of real frequency sound waves; The synthesizer is used to perform weighted superposition of the plurality of real-frequency sound waves according to preset weights to form the complex-frequency sound wave.

2. The acoustic delay line device according to claim 1, characterized in that: The amplitude function V of the complex frequency sound wave is expressed as: V=Cexp(-βt), wherein C is a constant, β=αv, α is the Rayleigh damping loss parameter of the substrate, and v represents the sound velocity.

3. The acoustic delay line device according to claim 1, characterized in that: The real frequency ω corresponding to the displacement field of the i-th real frequency sound wave among the plurality of real frequency sound waves i is the angular frequency of the i-th point after the series expansion of the displacement field integral of the complex frequency sound wave.

4. The acoustic delay line device according to claim 1, characterized in that: The preset weight of the i-th real frequency sound wave among the plurality of real frequency sound waves is Among them, C(ω i ) is the preset weight of the ith real frequency sound wave, is the angular frequency of the complex frequency sound wave, ω i is the angular frequency of the i-th point after the series expansion of the displacement field integral of the complex frequency sound wave, Δω i is the angular frequency ω of the i-th point after the series expansion of the displacement field integral of the complex frequency sound wave i The angular frequency ω of the i+1th point after series expansion of the displacement field integral of the complex frequency sound wave i+1 The frequency difference between them.

5. The acoustic delay line device according to claim 1, characterized in that: The substrate is a piezoelectric material; the piezoelectric material includes at least one of lithium niobate and lithium tantalate.

6. The acoustic delay line device according to claim 1, characterized in that: The substrate is a piezoelectric heterogeneous material.

7. The acoustic delay line device according to claim 1, characterized in that: The first transducer and the second transducer are both made of metal materials; the metal material includes at least one of aluminum, gold, copper, tungsten, and platinum.

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