Frequency filter and method for manufacturing frequency filter

Abstract

The present disclosure provides a frequency filter that operates in a high frequency band. A frequency filter is provided with a dielectric layer, an input-side comb electrode, and an output-side comb electrode. The dielectric layer has flexoelectric characteristics. The input side comb tooth electrode is arranged on the dielectric layer. And the output side comb tooth electrode is arranged on the dielectric layer. The dielectric layer makes it possible to generate an elastic wave in the dielectric layer corresponding to an input electric field in the input-side comb electrode; and generating an output electric field corresponding to the elastic wave in the output-side comb electrode.

Description

Technical Field

[0001] The present disclosure relates to a frequency filter and a method for manufacturing the frequency filter. Background Art

[0002] A frequency filter is mounted in a wireless communication system. Patent Document 1 discloses a surface acoustic wave (SAW) filter as a frequency filter.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2022-51000 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] In SAW filters, the thinner the piezoelectric element that transmits elastic waves, the faster the propagation speed and the less energy loss. However, as the frequency band used increases, the improvement of SAW filter characteristics has reached its limit.

[0008] In order to solve the above-mentioned problems, an object of the present disclosure is to provide a frequency filter capable of operating in a high frequency band.

[0009] Means used to solve problems

[0010] The frequency filter disclosed herein comprises a dielectric layer, an input-side comb-tooth electrode, and an output-side comb-tooth electrode. The dielectric layer has flexoelectric properties. The input-side comb-tooth electrode is disposed on the dielectric layer. The output-side comb-tooth electrode is disposed on the dielectric layer. The dielectric layer is capable of generating elastic waves in the dielectric layer corresponding to an input electric field in the input-side comb-tooth electrode, and generating an output electric field corresponding to the elastic waves in the output-side comb-tooth electrode.

[0011] Effects of the Invention

[0012] According to the present disclosure, a frequency filter capable of operating in a high frequency band is provided.

[0013] The objects, features, aspects and advantages of the present disclosure will be further illustrated by the following detailed description and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a perspective view showing the structure of the frequency filter in the first embodiment.

[0015] Figure 2 It is a perspective view showing the structure of a frequency filter in the second embodiment.

[0016] Figure 3 This is a plan view showing the structure of an input-side comb-teeth electrode in the second embodiment.

[0017] Figure 4 This is a plan view showing the structure of an input-side comb-teeth electrode in Modification 1 of Embodiment 2. DETAILED DESCRIPTION

[0018] <Implementation Method 1>

[0019] Figure 1 This is a perspective view showing the structure of the frequency filter 10 in Embodiment 1. The frequency filter 10 is a surface acoustic wave (SAW) filter for high frequencies.

[0020] The frequency filter 10 includes a dielectric layer 11 , an input-side comb-shaped electrode 12 , an output-side comb-shaped electrode 13 , an input-side wiring 14 , and an output-side wiring 15 .

[0021] The dielectric layer 11 has flexoelectric properties. In this specification, the flexoelectric effect and the inverse flexoelectric effect are collectively referred to as flexoelectric properties, but this property may also be simply referred to as the flexoelectric effect.

[0022] In dielectric layer 11 with flexoelectric properties, an electric field is generated based on the distortion gradient within the dielectric layer 11. This is called the flexoelectric effect. Furthermore, a distortion gradient is generated within dielectric layer 11 based on the electric field. This is called the inverse flexoelectric effect.

[0023] Dielectric layer 11 generates elastic waves that respond to the input electric field in input-side comb-teeth electrodes 12 and are excited by the inverse flexoelectric properties of dielectric layer 11. These elastic waves propagate through dielectric layer 11. Furthermore, dielectric layer 11 generates an output electric field that responds to the elastic waves in output-side comb-teeth electrodes 13 and is converted from these elastic waves by the flexoelectric properties of dielectric layer 11. The elastic waves propagating through dielectric layer 11 are also called surface elastic waves.

[0024] The dielectric layer 11 in the first embodiment is formed by a single-layer or multi-layer two-dimensional thin film 11A. The two-dimensional thin film 11A has a two-dimensional bonding structure of atoms. The multi-layer two-dimensional thin film has a structure formed by stacking single-layer two-dimensional thin films. Van der Waals forces act between the layers, and the multi-layer two-dimensional thin films are bonded to each other by the van der Waals forces. The two-dimensional thin film 11A is formed, for example, of an insulating material or a semiconductor material. The two-dimensional thin film 11A is formed, for example, of hexagonal boron nitride, molybdenum disulfide, and molybdenum telluride. The thickness of the two-dimensional thin film 11A is a single atom or less than 10 nm. The thickness of the two-dimensional thin film 11A is a thickness at which the flexoelectric properties in the two-dimensional thin film 11A are greater than the piezoelectric properties. The dielectric layer 11 is not limited to the two-dimensional thin film 11A. The dielectric layer 11 can be formed of a non-piezoelectric insulating material.

[0025] The input-side comb-tooth electrode 12 is disposed on the two-dimensional thin film 11A. The input-side comb-tooth electrode 12 has two comb teeth. The two comb teeth are arranged opposite each other to form a nested structure. The comb teeth in the input-side comb-tooth electrode 12 have one or more parallel portions. The input-side comb-tooth electrode 12 is formed of a conductive material. The input-side comb-tooth electrode 12 is formed of, for example, copper, gold, aluminum, and graphene. An input signal is input to the input-side comb-tooth electrode 12. An electric field corresponding to the spacing between the comb teeth of the input-side comb-tooth electrode 12 is formed in the comb teeth.

[0026] The output side comb-tooth electrode 13 is arranged on the same two-dimensional thin film 11A. The output side comb-tooth electrode 13 has two comb teeth. The two comb teeth are arranged opposite to each other to form a nested structure. The comb teeth in the output side comb-tooth electrode 13 are arranged parallel to the comb teeth in the input side comb-tooth electrode 12. The comb tooth spacing in the input side comb-tooth electrode 12 is equal to the comb tooth spacing in the output side comb-tooth electrode 13. The comb teeth in the output side comb-tooth electrode 13 have one or more parallel portions. The output side comb-tooth electrode 13 is formed of a conductive material. The output side comb-tooth electrode 13 is formed of, for example, copper, gold, aluminum, and graphene. The elastic wave generated in the input side comb-tooth electrode 12 reaches the output side comb-tooth electrode 13. An electric field corresponding to the elastic wave is formed at the comb teeth of the output side comb-tooth electrode 13.

[0027] The input-side wiring 14 is electrically connected to the input-side comb-teeth electrode 12 . An input signal is applied to the input-side comb-teeth electrode 12 via the input-side wiring 14 .

[0028] The output-side wiring 15 is electrically connected to the output-side comb-teeth electrode 13. An output signal corresponding to the electric field in the output-side comb-teeth electrode 13 is taken out to the outside through the output-side wiring 15.

[0029] Next, the method for manufacturing the frequency filter 10 is described. First, a dielectric layer 11 is formed. Dielectric layer 11 has flexoelectric properties. Here, a single-layer or multi-layer two-dimensional thin film 11A is formed. Two-dimensional thin film 11A is fabricated using the Scotch tape method or molecular beam epitaxy. Then, the input-side comb-tooth electrodes 12 and the output-side comb-tooth electrodes 13 are vapor-deposited onto the two-dimensional thin film 11A.

[0030] Next, the operation of frequency filter 10 will be described. An input signal containing multiple frequency components is input from an external circuit via input-side wiring 14 to input-side comb-tooth electrode 12. This input signal is a high-frequency signal, for example, containing random frequency components. An electric field corresponding to the inter-tooth spacing is generated between the teeth of input-side comb-tooth electrode 12. This electric field generates a distortion gradient within two-dimensional thin film 11A through the inverse flexoelectric effect, exciting elastic waves.

[0031] The elastic wave propagates through the two-dimensional thin film 11A and reaches the output-side comb-tooth electrode 13. In the output-side comb-tooth electrode 13, a distortion gradient corresponding to the frequency of the elastic wave is generated within the two-dimensional thin film 11A. The flexoelectric effect generates an electric field corresponding to this distortion gradient between the comb teeth. An output signal corresponding to this electric field is output externally via the output-side wiring 15.

[0032] In the above, only the output signal of a specific frequency is extracted from the input signal containing multiple frequency components. In other words, only the specific frequency passes through the frequency filter 10.

[0033] The frequency of the signal output to the outside is calculated by the following formula (1).

[0034] [Mathematical formula 1]

[0035]

[0036] Here, f represents frequency, v represents propagation velocity of elastic waves, and λ represents the wavelength of elastic waves excited in input-side comb-teeth electrode 12 , that is, the comb-teeth interval.

[0037] In addition, the propagation velocity v is calculated by the following formula (2).

[0038] [Mathematical formula 2]

[0039]

[0040] Here, ρ represents density and E represents elastic modulus. The greater the propagation velocity v and the smaller the comb tooth spacing λ, the greater the frequency f.

[0041] In summary, the frequency filter 10 in Embodiment 1 includes a dielectric layer 11, an input-side comb-teeth electrode 12, and an output-side comb-teeth electrode 13. The dielectric layer 11 has flexoelectric properties. The input-side comb-teeth electrode 12 is disposed on the dielectric layer 11. The output-side comb-teeth electrode 13 is disposed on the dielectric layer 11. The dielectric layer 11 enables the generation of elastic waves in the dielectric layer 11 corresponding to the input electric field in the input-side comb-teeth electrode 12, and the generation of an output electric field corresponding to the elastic wave in the output-side comb-teeth electrode 13.

[0042] When the dielectric layer 11 is a two-dimensional thin film 11A, the device can be thinned to atomic size. Elastic waves do not propagate in the thickness direction of the two-dimensional thin film 11A. In addition, by reducing the size of the dielectric layer 11 through which the elastic waves propagate, the probability of defects in the dielectric layer 11 is reduced. Therefore, elastic waves are not easily attenuated. Even when the dielectric layer 11 is a multi-layer two-dimensional thin film 11A, the friction between the layers is small, so the energy dissipation is also small. From the above, it can be seen that elastic waves are not easily attenuated in the frequency filter 10. The frequency filter 10 can be applied to high-frequency devices. In addition, the two-dimensional thin film 11A responds electrically sensitively to deformation compared to bulk materials. This is also an advantage.

[0043] In frequency filters using piezoelectric elements, the piezoelectric effect disappears when the size is reduced to a few nanometers or less. Therefore, there is a limit to how much performance can be improved in high-frequency devices using piezoelectric elements. On the other hand, the frequency filter 10 of Embodiment 1 can also be applied to devices utilizing high frequencies exceeding several GHz, thus enabling device miniaturization.

[0044] <Implementation Method 2>

[0045] In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals.

[0046] Figure 2 It is a perspective view showing the structure of the frequency filter 20 in Embodiment 2. The frequency filter 20 includes an input-side comb-teeth electrode 22 and an output-side comb-teeth electrode 23 . Figure 3 It is a plan view showing the structure of the input-side comb-teeth electrode 22 in the second embodiment.

[0047] The input-side comb-tooth electrode 22 includes a first input-side comb-tooth portion 22A, a second input-side comb-tooth portion 22B, and a curved portion 22C. The second input-side comb-tooth portion 22B is angled relative to the first input-side comb-tooth portion 22A and is electrically connected to the first input-side comb-tooth portion 22A. In Embodiment 2, the first input-side comb-tooth portion 22A is connected to the second input-side comb-tooth portion 22B via the curved portion 22C. The comb teeth in the first input-side comb-tooth portion 22A are parallel to each other, and the comb teeth in the second input-side comb-tooth portion 22B are also parallel to each other. The comb-tooth spacing of the second input-side comb-tooth portion 22B is equal to the comb-tooth spacing of the first input-side comb-tooth portion 22A.

[0048] The output-side comb-tooth electrode 23 includes a first output-side comb-tooth electrode 23A and a second output-side comb-tooth electrode 23B. The second output-side comb-tooth electrode 23B is provided separately from the first output-side comb-tooth electrode 23A. The first output-side comb-tooth electrode 23A has comb teeth parallel to the first input-side comb-tooth portion 22A. The second output-side comb-tooth electrode 23B has comb teeth parallel to the second input-side comb-tooth portion 22B.

[0049] An input signal containing a random frequency component is input from an external circuit to the input side comb electrode 22 through the input side wiring 14. The input signal is a high-frequency signal. An electric field corresponding to the comb tooth spacing is generated between the comb teeth of the first input side comb tooth portion 22A and between the comb teeth of the second input side comb tooth portion 22B. Through the inverse flexoelectric effect, a distortion gradient based on the electric field is generated in the two-dimensional film 11A, exciting elastic waves. In embodiment 2, the comb tooth spacing of the first input side comb tooth portion 22A and the comb tooth spacing of the second input side comb tooth portion 22B are equal to each other. Therefore, the wavelength of the elastic wave excited in the first input side comb tooth portion 22A is equal to the wavelength of the elastic wave excited in the second input side comb tooth portion 22B. In formula (1), the wavelength λ of the first input side comb tooth portion 22A and the wavelength λ of the second input side comb tooth portion 22B are equal to each other.

[0050] The elastic waves generated by the first input-side comb-tooth portion 22A propagate through the two-dimensional thin film 11A, reaching, for example, the first output-side comb-tooth electrode 23A. The elastic waves generated by the second input-side comb-tooth portion 22B propagate through the two-dimensional thin film 11A, reaching, for example, the second output-side comb-tooth electrode 23B. Distortion gradients corresponding to the frequencies of the elastic waves are generated within the two-dimensional thin film 11A in the first and second output-side comb-tooth electrodes 23A and 23B, respectively. Through the flexoelectric effect, electric fields corresponding to these distortion gradients are generated between the teeth of the first and second output-side comb-tooth electrodes 23A and 23B, respectively. An output signal corresponding to these electric fields is output externally via the output-side wiring 15.

[0051] Thus, only the output signal of a specific frequency is extracted from the input signal containing random frequency components. In other words, only the specific frequency passes through the frequency filter 20. In the second embodiment, the inter-tooth spacing of the first input-side comb-tooth portion 22A and the inter-tooth spacing of the second input-side comb-tooth portion 22B are equal, so for a single input signal, two output signals with the same frequency can be obtained from two locations.

[0052] (Variation 1 of Implementation 2)

[0053] Figure 4 It is a plan view showing the structure of the input-side comb-shaped electrode 32 in the first modification of the second embodiment.

[0054] The input-side comb-tooth electrode 32 includes a first input-side comb-tooth portion 32A and a second input-side comb-tooth portion 32B. The second input-side comb-tooth portion 32B is angled relative to the first input-side comb-tooth portion 32A and is electrically connected to the first input-side comb-tooth portion 32A. The teeth of the second input-side comb-tooth portion 32B are spaced apart from the teeth of the first input-side comb-tooth portion 32A.

[0055] In this case, the distribution of the electric field generated between the teeth of the first input-side comb-tooth portion 32A differs from the distribution of the electric field generated between the teeth of the second input-side comb-tooth portion 32B. Regarding the inverse flexoelectric effect, the distortion gradient generated by the first input-side comb-tooth portion 32A also differs from the distortion gradient generated by the second input-side comb-tooth portion 32B. Therefore, the wavelength of the elastic wave excited in the first input-side comb-tooth portion 32A differs from the wavelength of the elastic wave excited in the second input-side comb-tooth portion 32B. In equation (1), the wavelength λ of the first input-side comb-tooth portion 32A differs from the wavelength λ of the second input-side comb-tooth portion 32B.

[0056] The elastic waves generated by the first input-side comb-tooth portion 32A propagate through the two-dimensional thin film 11A, for example, reaching the first output-side comb-tooth electrode 23A. The elastic waves generated by the second input-side comb-tooth portion 32B propagate through the two-dimensional thin film 11A, for example, reaching the second output-side comb-tooth electrode 23B. A distortion gradient corresponding to the frequency of the elastic waves is generated within the two-dimensional thin film 11A in each of the first and second output-side comb-tooth electrodes 23A and 23B. Through the flexoelectric effect, an electric field corresponding to this distortion gradient is generated between the comb teeth of the first and second output-side comb-tooth electrodes 23A and 23B. An output signal corresponding to this electric field is output externally via the output-side wiring 15. The frequency of the output signal output from the first output-side comb-tooth electrode 23A differs from the frequency of the output signal output from the second output-side comb-tooth electrode 23B.

[0057] In this way, for one input signal, two output signals having different frequencies can be obtained.

[0058] (Variation 2 of Implementation 2)

[0059] The two-dimensional film 11A may also have anisotropic elastic modulus within the plane of the two-dimensional film 11A. In this case, the propagation velocity v of the elastic wave in equation (2) varies depending on its propagation direction. Therefore, the frequency of the elastic wave in equation (1) also varies depending on the propagation direction.

[0060] With such a configuration, even when the inter-comb tooth spacing of the second input-side comb-tooth portion 22B is equal to the inter-comb tooth spacing of the first input-side comb-tooth portion 22A, two output signals having different frequencies can be obtained.

[0061] <Implementation Method 3>

[0062] In the third embodiment, the same components as those in the first or second embodiment are denoted by the same reference numerals.

[0063] In Embodiment 3, dielectric layer 11 is formed from an insulating substrate (not shown) made of an insulating material. When dielectric layer 11 is an insulating substrate made of an insulating material, the flexoelectric effect and the inverse flexoelectric effect occur in the insulating material. Input-side comb-teeth electrodes 22 and output-side comb-teeth electrodes 23 are provided on this insulating substrate.

[0064] Same as implementation 2, refer to Figure 3 The input side comb-tooth electrode 22 includes a first input side comb-tooth portion 22A, a second input side comb-tooth portion 22B and a bent portion 22C. The second input side comb-tooth portion 22B has an angle relative to the first input side comb-tooth portion 22A and is electrically connected to the first input side comb-tooth portion 22A. The first input side comb-tooth portion 22A in embodiment 3 is connected to the second input side comb-tooth portion 22B via the bent portion 22C. The comb teeth in the first input side comb-tooth portion 22A are parallel to each other, and the comb teeth in the second input side comb-tooth portion 22B are also parallel to each other. The comb tooth spacing of the second input side comb-tooth portion 22B may be equal to or different from the comb tooth spacing of the first input side comb-tooth portion 22A.

[0065] Reference Figure 2 The output-side comb-tooth electrode 23 includes a first output-side comb-tooth electrode 23A and a second output-side comb-tooth electrode 23B. The second output-side comb-tooth electrode 23B is provided separately from the first output-side comb-tooth electrode 23A. The first output-side comb-tooth electrode 23A has comb teeth parallel to the first input-side comb-tooth portion 22A. The second output-side comb-tooth electrode 23B has comb teeth parallel to the second input-side comb-tooth portion 22B.

[0066] An input signal containing a random frequency component is input from an external circuit to the input side comb electrode 22 through the input side wiring 14. The input signal is a high-frequency signal. An electric field corresponding to the comb tooth spacing is generated between the comb teeth of the first input side comb tooth portion 22A and between the comb teeth of the second input side comb tooth portion 22B. Through the inverse flexoelectric effect, a distortion gradient based on the electric field is generated in the insulating material, and elastic waves are excited. When the comb tooth spacing of the first input side comb tooth portion 22A and the comb tooth spacing of the second input side comb tooth portion 22B are equal to each other, elastic waves of the same wavelength are excited. In this case, in formula (1), the wavelength λ is the same value. On the other hand, when the comb tooth spacing of the first input side comb tooth portion 22A and the comb tooth spacing of the second input side comb tooth portion 22B are different from each other, elastic waves of different wavelengths are excited. In this case, in formula (1), the wavelength λ is a different value.

[0067] The elastic wave propagates through the insulating substrate 11B, which is made of an insulating material, and reaches the first and second output-side comb-teeth electrodes 23A and 23B. A distortion gradient corresponding to the frequency of the elastic wave is generated within the insulating material of each of the first and second output-side comb-teeth electrodes 23A and 23B. Through the flexoelectric effect, an electric field corresponding to this distortion gradient is generated between the teeth of the first and second output-side comb-teeth electrodes 23A and 23B. An output signal corresponding to this electric field is output externally via the output-side wiring 15.

[0068] As in Embodiment 2, two output signals having the same frequency or two output signals having different frequencies can be obtained for a single input signal containing random frequency components. This reduces the number of components compared to the case of forming an electrical circuit and obtaining two output signals.

[0069] While the present disclosure has been described in detail, the foregoing description is in all aspects illustrative and not restrictive, and it is understood that numerous variations and modifications not shown are conceivable.

[0070] In the present disclosure, each embodiment can be freely combined or each embodiment can be appropriately modified or omitted.

[0071] Description of Reference Numerals

[0072] 10 frequency filter; 11 dielectric layer; 11A two-dimensional thin film; 12 input side comb-tooth electrode; 13 output side comb-tooth electrode; 14 input side wiring; 15 output side wiring; 20 frequency filter; 22 input side comb-tooth electrode; 22A first input side comb-tooth portion; 22B second input side comb-tooth portion; 22C bending portion; 23 output side comb-tooth electrode; 23A first output side comb-tooth electrode; 23B second output side comb-tooth electrode; 32 input side comb-tooth electrode; 32A first input side comb-tooth portion; 32B second input side comb-tooth portion.

Claims

1. A frequency filter, wherein: have: a dielectric layer having flexoelectric properties; an input-side comb-tooth electrode, disposed on the dielectric layer; and The output side comb-tooth electrode is arranged on the dielectric layer, The dielectric layer enables: generating elastic waves in the dielectric layer corresponding to an input electric field in the input-side comb-teeth electrode; and generating an output electric field corresponding to the elastic waves in the output-side comb-teeth electrode.

2. The frequency filter according to claim 1, wherein The dielectric layer includes a single-layer or multi-layer two-dimensional thin film.

3. The frequency filter according to claim 2, wherein The flexoelectric property in the two-dimensional thin film is greater than the piezoelectric property in the two-dimensional thin film.

4. The frequency filter according to claim 2 or 3, wherein: The thickness of the two-dimensional film is a single atom or less than 10 nm.

5. The frequency filter according to any one of claims 2 to 4, wherein The two-dimensional thin film is formed of any material selected from the group consisting of hexagonal boron nitride, molybdenum disulfide, and molybdenum telluride.

6. The frequency filter according to any one of claims 2 to 5, wherein In the two-dimensional thin film, an elastic modulus within a plane of the two-dimensional thin film has anisotropy.

7. The frequency filter according to claim 1, wherein The dielectric layer is formed of a non-piezoelectric insulating material.

8. The frequency filter according to any one of claims 1 to 7, wherein The input-side comb-tooth electrodes and the output-side comb-tooth electrodes are formed of any material selected from copper, gold, aluminum, and graphene.

9. The frequency filter according to any one of claims 1 to 8, wherein The comb teeth of the output-side comb-tooth electrode are arranged in parallel with the comb teeth of the input-side comb-tooth electrode.

10. The frequency filter according to any one of claims 1 to 9, wherein The comb teeth interval in the output-side comb-teeth electrode is equal to the comb teeth interval in the input-side comb-teeth electrode.

11. The frequency filter according to any one of claims 1 to 8, wherein The input-side comb-tooth electrode comprises: a first input-side comb-tooth portion; and The second input-side comb-tooth portion has an angle with respect to the first input-side comb-tooth portion and is electrically connected to the first input-side comb-tooth portion. The output-side comb-tooth electrode comprises: a first output-side comb-tooth electrode having comb teeth parallel to the first input-side comb-tooth portion; and The second output-side comb-tooth electrode is provided separately from the first output-side comb-tooth electrode and has comb teeth parallel to the second input-side comb-tooth portion.

12. The frequency filter according to claim 11, wherein The comb teeth interval of the second input-side comb-tooth portion is equal to the comb teeth interval of the first input-side comb-tooth portion.

13. The frequency filter according to claim 11, wherein The comb tooth interval of the second input-side comb tooth portion is different from the comb tooth interval of the first input-side comb tooth portion.

14. The frequency filter according to any one of claims 1 to 13, wherein Also features: an input-side wiring electrically connected to the input-side comb-tooth electrode; and The output-side wiring is electrically connected to the output-side comb-tooth electrode.

15. The frequency filter according to claim 1, wherein The dielectric layer includes an insulating substrate made of insulating material.

16. A method for manufacturing a frequency filter, wherein: have: forming a dielectric layer having flexoelectric properties; and a process of evaporating an input-side comb-tooth electrode and an output-side comb-tooth electrode on the dielectric layer; The dielectric layer enables: generating elastic waves in the dielectric layer corresponding to an input electric field in the input-side comb-teeth electrode; and generating an output electric field corresponding to the elastic waves in the output-side comb-teeth electrode.

17. The method for manufacturing a frequency filter according to claim 16, wherein: The dielectric layer includes a single-layer or multi-layer two-dimensional thin film.

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