Micro-thermal on-chip sound wave phase modulator

Abstract

The invention provides a micro-thermal on-chip acoustic wave phase modulator, which belongs to the technical field of signal processing and comprises a substrate, a piezoelectric film and a micro heater. Wherein the piezoelectric film is arranged on the substrate, and the piezoelectric film is a lithium niobate film, a lithium tantalate film, an aluminum nitride film, an aluminum scandium nitride film or a gallium nitride film; the micro heater is arranged on the piezoelectric film; a cavity is formed between the substrate and the piezoelectric film, and the projection of the micro heater on the substrate in the height direction is located in the cavity. According to the micro-thermal on-chip sound wave phase modulator, effective phase modulation of incident sound waves is achieved through the thermo-acoustic effect of the lithium niobate thin film, and it is ensured that the heating temperature can be well limited in a modulation area based on the good thermal isolation performance and the low thermal capacity of the suspended thin film device; the excitation power consumption of the acoustic wave phase modulator is effectively reduced, and the response speed of the acoustic wave phase modulator is increased.

Description

Technical Field

[0001] The invention relates to the technical field of signal processing, and in particular to a micro-thermal on-chip acoustic wave phase modulator. Background Art

[0002] With the development of communication and signal processing technology, microwave acoustic modulation devices, especially phase modulators, have received widespread attention and are widely used in beamforming, signal modulation, radar target tracking and other fields.

[0003] Currently, although the phase modulator based on electroacoustic modulation technology can achieve effective modulation of the phase of the incident sound field, it is usually necessary to apply a higher voltage to the phase modulator to produce significant phase modulation of the incident sound wave. For example, the phase modulator using AlScN material can use a vertical electric field to reduce the voltage requirement, but it is still necessary to apply a modulation voltage of more than 60V to the phase modulator to achieve a modulation change of π phase.

[0004] Although thermoacoustic phase modulators provide an alternative to low-voltage excitation phase modulators, the existing thermal acoustic phase modulators based on the surface acoustic wave (SAW) platform face problems such as high power consumption and slow response speed, so they are effectively used in the market.

[0005] Therefore, it is necessary to provide a micro-thermal on-chip acoustic wave phase modulator to solve the above technical problems. Summary of the invention

[0006] In view of the above problems existing in the prior art, the present invention provides a micro-thermal on-chip acoustic wave phase modulator to improve the technical defects of the existing acoustic wave phase modulator that it is difficult to achieve low excitation voltage, low excitation power consumption and high response speed.

[0007] To achieve the above-mentioned object and other related objects, the present invention provides a microthermal on-chip acoustic wave phase modulator, which includes a substrate, a piezoelectric film and a microheater.

[0008] Among them, the piezoelectric film is arranged on the substrate, and the piezoelectric film is a lithium niobate film, a lithium tantalate film, an aluminum nitride film, a scandium aluminum nitride film or a gallium nitride film; the microheater is arranged on the piezoelectric film; there is a cavity between the substrate and the piezoelectric film, and the projection of the microheater on the substrate along the height direction is located in the cavity.

[0009] In one example of the present invention, under the heating of the microheater, the piezoelectric film produces phase modulation on the incident sound wave, wherein the angle of the phase modulation is positively correlated with the modulation length and the modulation temperature, the modulation temperature is the heating temperature of the piezoelectric film by the microheater, and the modulation length is the heating length of the piezoelectric film by the microheater in the direction of sound wave transmission.

[0010] In an example of the present invention, the substrate is a silicon substrate.

[0011] In an example of the present invention, the microheater includes a heating element, the heating element is attached to the piezoelectric film, and the material of the heating element is titanium, gold, platinum or aluminum.

[0012] In an example of the present invention, the material of the micro heater is aluminum.

[0013] In an example of the present invention, when the piezoelectric film is a lithium niobate film, the phase delay response of the microthermal on-chip acoustic wave phase modulator per unit micron modulation length is 0.973° / mW·μm.

[0014] In an example of the present invention, the thickness of the piezoelectric film is 0.05λ-0.5λ, where λ is the wavelength of the acoustic wave incident into the microthermal on-chip acoustic wave phase modulator.

[0015] In an example of the present invention, the micro-thermal on-chip acoustic wave phase modulator also includes an acoustic wave transmitter and an acoustic wave receiver, wherein the acoustic wave transmitter and the acoustic wave receiver are arranged on the piezoelectric film, and the acoustic wave transmitter and the acoustic wave receiver are respectively located on both sides of the micro-heater, and the projections of the acoustic wave transmitter and the acoustic wave receiver on the substrate along the height direction are located in the cavity.

[0016] In one example of the present invention, the sound wave transmitter and the sound wave receiver are single-phase unidirectional transducers, and the single-phase unidirectional transducer includes multiple groups of electrode units, and the multiple groups of electrode units are arranged on the surface of the piezoelectric film, and the electrode unit includes an excitation electrode and a ground electrode.

[0017] In an example of the present invention, the width of the excitation electrode is 1 / 8 of the width of the electrode unit, and the width of the grounding electrode is 3 / 8 of the width of the electrode unit.

[0018] The micro-thermal on-chip acoustic wave phase modulator of the present invention is provided with a suspended lithium niobate film on a substrate as a phase modulation device. The micro-thermal on-chip acoustic wave phase modulator realizes effective phase modulation of the incident acoustic wave through the thermoacoustic effect of the lithium niobate film, and based on the good thermal isolation and low heat capacity of the suspended film device, ensures that the heating temperature can be well limited within the modulation area, thereby effectively reducing the excitation power consumption of the acoustic wave phase modulation device and accelerating the response speed of the acoustic wave phase modulation device. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other embodiments can be obtained based on these drawings without paying creative work.

[0020] Figure 1 It is a schematic diagram of the structure of a micro-thermal on-chip acoustic wave phase modulator according to an embodiment of the present invention;

[0021] Figure 2 A schematic diagram of the working principle of a micro-thermal on-chip acoustic wave phase modulator according to an embodiment of the present invention;

[0022] Figure 3 (a) is a cross-sectional view and a top view of the thermal distribution of the piezoelectric film heated by the microheater at a modulation voltage of 1 V; Figure 3 (b) is the relationship between the microheater output power and the heating temperature; Figure 3 (c) is the transient thermal response curve of piezoelectric films with different thicknesses to microheater heating under constant modulation voltage;

[0023] Figure 4 The transmission coefficient S of the micro-thermal on-chip acoustic wave phase modulator for the incident acoustic wave in the frequency range of 3.5 GHz to 3.6 GHz under the modulation of micro-heaters of different materials 21 The simulation results of

[0024] Figure 5 A schematic diagram of the working principle of a single-phase unidirectional transducer on a lithium niobate film in one embodiment of the present invention;

[0025] Figure 6 The figure is a dispersion curve of a Z-cut lithium niobate film and a relationship diagram between the electromechanical coupling coefficient (K2) and the output acoustic wave wavelength of a single-phase unidirectional transducer in an A1 working mode in one embodiment of the present invention;

[0026] Figure 7 (a) is a schematic diagram of the structure of a micro-thermal on-chip acoustic wave phase modulator according to an embodiment of the present invention; Figure 7(b) is the transmission coefficient S of the microthermal on-chip acoustic wave phase modulator for incident acoustic waves at 3.5 GHz to 3.6 GHz at different modulation voltages 21 Test results; Figure 7 (c) is the phase change angle of the incident sound wave of 3.5 GHz to 3.6 GHz transmitted from the sound wave transmitter to the sound wave receiver under the modulation of different modulation voltage excitations; Figure 7 (d) is the transfer coefficient S 21 Graph of maximum value versus modulation voltage; Figure 7 (e) is the phase modulation angle of the microthermal on-chip acoustic wave phase modulator for incident acoustic waves ranging from 3.5 GHz to 3.6 GHz at different modulation voltages.

[0027] Figure 8 Graph showing the relationship between the phase modulation angle of the acoustic wave of the micro-thermal on-chip acoustic wave phase modulator and the modulation voltage applied to the micro-heater in one embodiment of the present invention ( Figure 8 (a)), and the relationship between the microheater output power ( Figure 8 (b)).

[0028] Component number description

[0029] 10. Substrate; 11. Cavity; 20. Piezoelectric film; 30. Micro heater; 40. Sound wave transmitter; 50. Sound wave receiver. DETAILED DESCRIPTION

[0030] The following is an explanation of the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the features in the following embodiments and the embodiments can be combined with each other without conflict. It should also be understood that the terms used in the embodiments of the present invention are intended to describe specific embodiments, rather than to limit the scope of protection of the present invention. The test methods for which specific conditions are not specified in the following examples are usually carried out under conventional conditions or according to the conditions recommended by the manufacturers.

[0031] When numerical ranges are given in the embodiments, it should be understood that unless otherwise specified in the present invention, both endpoints of each numerical range and any value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention are familiar to those skilled in the art and the description of the present invention, and any method, device and material of the prior art similar or equivalent to the method, device and material in the embodiments of the present invention can also be used to implement the present invention.

[0032] It should be noted that the terms such as "upper", "lower", "left", "right", "middle" and "one" etc. used in this specification are only for the convenience of description and are not intended to limit the scope of implementation of the present invention. Changes or adjustments to their relative relationships, without substantially changing the technical content, should also be regarded as the scope of implementation of the present invention.

[0033] See also Figures 1 to 8 The present invention provides a micro-thermal on-chip acoustic wave phase modulator, which includes a substrate 10, a piezoelectric film 20 and a micro-heater 30.

[0034] like Figure 1 and Figure 2 As shown, the piezoelectric film 20 is arranged on the substrate 10, and the piezoelectric film 20 is a lithium niobate film, a lithium tantalate film, an aluminum nitride film, an aluminum nitride scandium film or a gallium nitride film cut along any crystal axis. For example, the piezoelectric film 20 can be a lithium niobate film cut in the Z direction (that is, the surface of the lithium niobate film is perpendicular to the Z axis direction). The microheater 30 is arranged on the piezoelectric film 20, and the microheater 30 is used to heat and modulate the preset thermal modulation area on the surface of the piezoelectric film 20, so that the thermal modulation area of ​​the piezoelectric film 20 is quickly heated to the modulation temperature. The part of the piezoelectric film 20 that is heated to the modulation temperature reduces the transmission speed of the sound wave transmitted along the surface of the piezoelectric film 20, shortens the wavelength of the sound wave, and then generates phase delay modulation on the sound wave. The angle of phase modulation is positively correlated with the modulation length and modulation temperature of the thermal modulation area in the piezoelectric film 20. The modulation temperature is the heating modulation temperature of the microheater 30 for the piezoelectric film 20, and the modulation length is the heating length of the microheater 30 for the piezoelectric film 20 in the transmission direction of the incident sound wave.

[0035] In some implementations, the microthermal on-chip acoustic wave phase modulator can achieve phase modulation of an incident acoustic wave at any delay angle by adjusting the modulation temperature and the modulation length. Specifically, the phase modulation angle P M It is expressed as the following relationship:

[0036]

[0037] where λ is the wavelength of the acoustic wave incident on the microthermal on-chip acoustic wave phase modulator, L M is the modulation length of the thermal modulation region in the piezoelectric film 20, T is the modulation temperature of the thermal modulation region in the piezoelectric film 20, (dv p ) / (dT) is the thermoacoustic modulation coefficient.

[0038] like Figure 1 and Figure 2As shown, there is an air cavity (referred to as cavity 11) between the substrate 10 and at least part of the piezoelectric film 20, and the cavity 11 allows at least part of the piezoelectric film 20 to be suspended on the substrate 10. The cavity 11 between the substrate 10 and the piezoelectric film 20 at least covers the thermal modulation area of ​​the microheater 30 on the surface of the piezoelectric film 20, specifically, in the height direction, the projection of the microheater 30 on the substrate 10 is located in the cavity 11. The cavity 11 provides an effective thermal insulation area for the suspended piezoelectric film 20, ensuring that the thermal distribution boundary of the modulated temperature of the piezoelectric film 20 under the microheater 30 is effectively restricted in the modulation area, thereby achieving precise control of phase modulation, and effectively improving the heating efficiency of the microheater 30 for the piezoelectric film 20, reducing the modulation power consumption of the microthermal on-chip acoustic wave phase modulator, and accelerating the response speed of the microthermal on-chip acoustic wave phase modulator.

[0039] It should be noted that the substrate 10 can be any base material that meets the growth requirements of the piezoelectric film 20. As an example, the substrate 10 can include any one or more combinations of semiconductor materials and insulating materials. When the substrate 10 is made of semiconductor materials, for example, single crystal silicon (Si), single crystal germanium (Ge), silicon germanium (SiGe), silicon carbide (SiC), gallium arsenide (GaAs), indium arsenide (InAs) or other III / V compound semiconductors can be selected. In addition to the semiconductor materials listed above, the substrate 10 can also be Si / SiGe, Si / SiC, silicon on insulator (SOI), germanium on insulator (GOI) or silicon germanium on insulator (SGOI), etc. When the substrate 10 is made of insulating material, the insulating material can be an organic insulator, an inorganic insulator or a combination thereof. In some embodiments, since the silicon substrate 10 has good thermal conductivity and can be used as the room temperature thermal boundary of the device, the present application takes the substrate 10 as a silicon substrate 10 as an example for detailed description.

[0040] like Figures 1 to 3 As shown in FIG. 1 , the microheater 30 includes a heating element, which is attached to the surface of the piezoelectric film 20. The heating element heats the piezoelectric film 20 after the modulation voltage is applied. The cross-sectional view and the top view of the heat distribution of the microheater 30 heating the piezoelectric film 20 under the 1V modulation voltage are shown in FIG. Figure 3 As shown in (a), Figure 3 (a) It can be seen that under the thermal insulation of the cavity 11 and the rapid heat dissipation of the surrounding substrate 10, the temperature boundary of the heat distribution is precisely limited in the thermal modulation area, which makes the micro-thermal on-chip acoustic wave phase modulator have extremely high modulation accuracy.

[0041] In some embodiments, the material of the heating element in the microheater 30 can be titanium, gold, platinum or aluminum. Optionally, the material of the heating element in the microheater 30 is aluminum, such as Figure 4As shown, the micro heater 30 will cause insertion loss to the sound waves transmitted on the surface of the piezoelectric film 20. Compared with metals such as titanium, gold, and platinum, the aluminum heating element has the smallest insertion loss to the sound waves transmitted on the surface of the piezoelectric film 20.

[0042] like Figure 3 As shown in (c), under a constant modulation voltage, the transient thermal response speed of the piezoelectric film 20 is inversely correlated with the heat capacity, so limiting the thickness of the piezoelectric film 20 to an appropriate range can further accelerate the response speed of the microthermal on-chip acoustic wave phase modulator. In some embodiments, the thickness of the piezoelectric film 20 is 0.05λ-0.5λ, where λ is the wavelength of the sound wave incident to the microthermal on-chip acoustic wave phase modulator. For example, when the wavelength of the sound wave incident to the microthermal on-chip acoustic wave phase modulator is 8μm, the thickness of the piezoelectric film 20 is 0.4μm to 4μm. The piezoelectric film 20 within the above thickness range can achieve a rapid response to the modulation temperature within 3ms when heated by the aluminum microheater 30. Optionally, the thickness of the piezoelectric film 20 is 0.06λ, that is, when the wavelength of the acoustic wave incident to the microthermal on-chip acoustic wave phase modulator is 8μm, the thickness of the piezoelectric film 20 is 0.5μm. The piezoelectric film 20 with a thickness of 0.5μm can be heated to the modulation temperature within 1ms when heated by the aluminum microheater 30.

[0043] In addition, if Figure 3 (b) Figure 7 and Figure 8 As shown, in some embodiments, when the piezoelectric film 20 is a lithium niobate film in the Z-cut direction and the heating element material of the microheater 30 is aluminum, the phase delay response of the microthermal on-chip acoustic wave phase modulator in the unit micron modulation length is 0.973° / mW·μm. For example, when the modulation length on the microthermal on-chip acoustic wave phase modulator is 100μm, a 0.62V modulation voltage is applied to the microheater 30, and the output power of the microheater 30 is 1.85mW, so that when the modulation temperature of the thermal modulation area in the piezoelectric film 20 rises to 80°C, the phase modulation angle of the microthermal on-chip acoustic wave phase modulator to the acoustic wave in the frequency band of 3.5GHz to 3.6GHz is 180°.

[0044] like Figure 5 to Figure 6As shown, the micro-thermal on-chip acoustic wave phase modulator also includes an acoustic wave transmitter 40 and an acoustic wave receiver 50, which are arranged on the surface of the piezoelectric film 20, and are respectively located on both sides of the micro-heater 30 on the surface of the piezoelectric film 20, and the projections of the acoustic wave transmitter 40 and the acoustic wave receiver 50 on the substrate 10 along the height direction are located in the cavity 11. At one end of the piezoelectric film 20, the acoustic wave transmitter 40 generates a single-phase acoustic wave that is transmitted in one direction under the modulation of the input electrical signal; at the other end of the piezoelectric film 20, the acoustic wave receiver 50 receives the single-phase acoustic wave transmitted along the surface of the piezoelectric film 20 and outputs an electrical signal. By comparing the output electrical signal with the input electrical signal, the transmission coefficient and phase modulation changes of the micro-thermal on-chip acoustic wave phase modulator for the acoustic wave before and after the thermal modulation can be obtained. In one example, the distance between the acoustic wave transmitter 40 and the acoustic wave receiver 50 is an even multiple of the wavelength of the acoustic wave, so that when the piezoelectric film 20 is not thermally modulated, the acoustic wave output from the acoustic wave transmitter 40 is in phase with the acoustic wave received by the acoustic wave receiver 50, thereby facilitating comparison of the phase modulation and amplitude attenuation of the acoustic wave caused by thermal modulation.

[0045] like Figure 5 As shown, in some embodiments, the acoustic wave transmitter 40 and the acoustic wave receiver 50 are both single-phase unidirectional transducers (SPUDTs), which include multiple groups of electrode units, which are arranged on the surface of the piezoelectric film 20, and the electrode units include excitation electrodes and ground electrodes. The excitation electrodes and ground electrodes in the multiple groups of electrode units are attached to the surface of the piezoelectric film 20 in the form of interdigitated electrodes. Among them, the single-phase unidirectional transducer as the acoustic wave transmitter 40 uses the piezoelectric effect to generate acoustic field disturbances on the surface of the piezoelectric film 20 under the excitation of the input electrical signal, forming a single-phase acoustic wave that is transmitted in one direction; the single-phase unidirectional transducer as the acoustic wave receiver 50 can respond to the acoustic field disturbances on the surface of the piezoelectric film 20 and convert the acoustic waves into output electrical signals. It should be noted that the electrode material in the single-phase unidirectional transducer can be selected from metal materials such as titanium, gold, platinum or aluminum. For example, in one example, the electrodes in the single-phase unidirectional transducer are selected from aluminum.

[0046] For example Figure 6 As shown, in one example, in a single-phase unidirectional transducer, the excitation electrode width is 1 / 8 of the electrode unit width, and the ground electrode width is 3 / 8 of the electrode unit width. The single-phase unidirectional transducer adopts the A1 acoustic mode and can generate high-frequency sound wave output in the frequency range of 3.5 GHz to 3.6 GHz on the piezoelectric film 20 with a high electromechanical conversion efficiency.

[0047] The technical scheme of the present invention is described in detail below through specific examples. Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by conventional methods in the art.

[0048] Example

[0049] like Figure 7 As shown in (a), this embodiment provides a microthermal on-chip acoustic wave phase modulator, which includes a silicon substrate 10, a Z-cut lithium niobate film disposed on the silicon substrate 10, and an aluminum microheater 30 disposed on the lithium niobate film. The thickness of the lithium niobate film is 750nm, the thickness of the heating element in the microheater 30 is 100nm, and the modulation length of the microheater 30 on the lithium niobate film is 100μm. The microthermal on-chip acoustic wave phase modulator is provided with two single-phase unidirectional transducers (SPUDTs) on the lithium niobate film as an acoustic wave transmitter 40 and an acoustic wave receiver 50. The two single-phase unidirectional transducers are located on both sides of the microheater 30 on the lithium niobate surface, so as to transmit and receive acoustic waves on the lithium niobate film. The single-phase unidirectional transducer as the acoustic wave transmitter 40 generates an acoustic wave with an operating frequency of 3.5 GHz to 3.6 GHz and a wavelength of 8 μm on the lithium niobate film in the A1 working mode at one end of the lithium niobate film. The single-phase unidirectional transducer as the acoustic wave receiver 50 generates an acoustic wave through the thermal modulation area at the other end of the lithium niobate film.

[0050] When the acoustic wave transmitter 40 and the acoustic wave receiver 50 are turned on, modulation voltages of 0V, 0.2V, 0.4V, 0.6V, 0.8V and 1V are respectively applied to the microheater 30 to test the phase modulation effect of the microthermal on-chip acoustic wave phase modulator on an acoustic wave with a wavelength of 8μm at different modulation temperatures.

[0051] like Figure 7 (b) and Figure 7 As shown in (d), the micro-thermal on-chip acoustic wave phase modulator does not produce a significant attenuation effect on the amplitude of the lithium niobate film acoustic wave under different modulation voltages (even when the lithium niobate film is at different modulation temperatures).

[0052] like Figure 7 (c) and Figure 7 As shown in (e), the phase modulation angle of the micro-thermal on-chip acoustic wave phase modulator is proportional to the modulation efficiency for 8μm acoustic waves. Figure 8 As shown, the microthermal on-chip acoustic wave phase modulator achieves a phase response of 97.3° / mW·μm, and can achieve a 180° phase shift for 8μm acoustic waves at a modulation voltage of 0.62V, showing excellent modulation efficiency.

[0053] In summary, the microthermal on-chip acoustic wave phase modulator realizes effective phase modulation of the incident acoustic wave through the thermoacoustic effect of lithium niobate film, and based on the good thermal isolation and low heat capacity of the suspended thin film device, ensures that the heating temperature can be well limited within the modulation area, thereby effectively reducing the excitation power consumption of the acoustic wave phase modulation device and accelerating the response speed of the acoustic wave phase modulation device.

[0054] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A micro-thermal on-chip acoustic wave phase modulator, characterized in that: include: substrate; A piezoelectric film, which is disposed on the substrate, wherein the piezoelectric film is a lithium niobate film, a lithium tantalate film, an aluminum nitride film, a scandium aluminum nitride film or a gallium nitride film; A micro heater, which is disposed on the piezoelectric film; There is a cavity between the substrate and the piezoelectric film, and the projection of the micro-heater on the substrate along the height direction is located in the cavity.

2. The microthermal on-chip acoustic wave phase modulator according to claim 1, characterized in that: Under the heating of the microheater, the piezoelectric film produces phase modulation on the incident sound wave, wherein the angle of the phase modulation is positively correlated with the modulation length and the modulation temperature, the modulation temperature is the heating temperature of the piezoelectric film by the microheater, and the modulation length is the heating length of the piezoelectric film by the microheater in the direction of sound wave transmission.

3. The microthermal on-chip acoustic wave phase modulator according to claim 1, characterized in that: The substrate is a silicon substrate.

4. The microthermal on-chip acoustic wave phase modulator according to claim 1, characterized in that: The micro heater comprises a heating element, the heating element is attached to the piezoelectric film, and the material of the heating element is titanium, gold, platinum or aluminum.

5. The microthermal on-chip acoustic wave phase modulator according to claim 3, characterized in that: The material of the micro heater is aluminum.

6. The microthermal on-chip acoustic wave phase modulator according to claim 5, characterized in that: When the piezoelectric film is a lithium niobate film, the phase delay response of the microthermal on-chip acoustic wave phase modulator per unit micron modulation length is 0.973° / mW·μm.

7. The microthermal on-chip acoustic wave phase modulator according to claim 1, characterized in that: The thickness of the piezoelectric film is 0.05λ-0.5λ, where λ is the wavelength of the acoustic wave incident into the microthermal on-chip acoustic wave phase modulator.

8. The microthermal on-chip acoustic wave phase modulator according to claim 1, characterized in that: The micro-thermal on-chip acoustic wave phase modulator also includes an acoustic wave transmitter and an acoustic wave receiver, wherein the acoustic wave transmitter and the acoustic wave receiver are arranged on the piezoelectric film, and the acoustic wave transmitter and the acoustic wave receiver are respectively located on both sides of the micro-heater, and the projections of the acoustic wave transmitter and the acoustic wave receiver on the substrate along the height direction are located in the cavity.

9. The microthermal on-chip acoustic wave phase modulator according to claim 8, characterized in that: The sound wave transmitter and the sound wave receiver are single-phase unidirectional transducers, which include multiple groups of electrode units arranged on the surface of the piezoelectric film, and the electrode units include an excitation electrode and a grounding electrode.

10. The microthermal on-chip acoustic wave phase modulator according to claim 9, characterized in that: The width of the excitation electrode is 1 / 8 of the width of the electrode unit, and the width of the grounding electrode is 3 / 8 of the width of the electrode unit.

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