A piezoelectric-thermo-optical composite modulator and its fabrication method

Abstract

This invention relates to the field of semiconductor technology and discloses a piezoelectric-thermo-optic composite modulator and its fabrication method. The piezoelectric-thermo-optic composite modulator includes: a silicon photonic integrated circuit structure, including a substrate layer and a waveguide core located on one side of the substrate layer; a thermo-optic modulation structure located on the side of the waveguide core facing away from the substrate layer; the thermo-optic modulation structure includes a heating fixed resistor and a thermo-optic electrode; the position of the heating fixed resistor corresponds to the position of the waveguide core; the thermo-optic electrode is connected to the heating fixed resistor; a piezoelectric modulation structure is located on the side of the waveguide core facing away from the substrate layer; the piezoelectric modulation structure includes a stacked first piezoelectric electrode, a piezoelectric thin film material layer, and a second piezoelectric electrode; the position of the piezoelectric thin film material layer corresponds to the position of the waveguide core; the first piezoelectric electrode further extends to the side of the piezoelectric thin film material layer. Compared with related technologies, this invention can simultaneously achieve piezoelectric modulation and thermo-optic modulation, reduce the driving voltage for π phase shift adjustment, and improve the modulation speed.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and specifically to a piezoelectric-thermo-optical composite modulator and its fabrication method. Background Technology

[0002] Silicon nitride (SiN) is characterized by low loss and compatibility with CMOS (Complementary Metal-Oxide-Semiconductor) processes, enabling the realization of high-performance passive devices. However, it lacks monolithically integrated high-speed devices, such as optical modulators. In integrated silicon-based optoelectronic chips, optical modulators can control the phase of light waves by changing the refractive index of the waveguide, thereby achieving chip function modulation. Among them, thermo-optic modulators are compatible with CMOS processes and can adjust the optical properties of waveguides by changing the temperature of the waveguide material. They play an important role in silicon photonic devices. Thermo-optic modulators can be used to achieve phase modulation, amplitude modulation, and polarization modulation of light beams, and are characterized by low power consumption and easy integration. However, their response time is generally on the order of microseconds (μs), and their modulation speed is relatively slow (~kHz). Piezoelectric modulators based on the inverse piezoelectric effect are also an important modulation device. When an external electric field is applied to a crystal material, the crystal material deforms. If the crystal material is combined with an optical waveguide, the stress of the crystal material deformation is transferred to the optical waveguide, thereby changing the refractive index of the optical waveguide. Compared to thermo-optic modulators, piezoelectric modulators can reduce power consumption by 3-5 orders of magnitude and also feature high modulation speeds (~GHz). However, they also suffer from issues such as high driving voltage and incompatibility with CMOS processes.

[0003] Current research on silicon nitride chip modulators is relatively limited. On silicon nitride photonic integration platforms, it is difficult to integrate modulators with different materials and properties in terms of process technology, especially for modulation of the same modulation region of the same waveguide. There is a lack of composite modulators that integrate modulators with different modulation characteristics in terms of process technology. Summary of the Invention

[0004] In view of this, the present invention provides a piezoelectric-thermo-optic composite modulator and its fabrication method to solve the problems of relatively slow response and modulation speed of thermo-optic modulators, high driving voltage for piezoelectric modulators to achieve π phase shift, and lack of composite modulators that integrate modulators with different modulation characteristics in the process of related technologies.

[0005] In a first aspect, the present invention provides a piezoelectric-thermo-optic composite modulator, the piezoelectric-thermo-optic composite modulator comprising:

[0006] A silicon photonic integrated circuit structure, including a substrate layer and a waveguide core located on one side of the substrate layer;

[0007] A thermo-optic modulation structure is located on the side of the waveguide core facing away from the substrate. The thermo-optic modulation structure includes a heating fixed resistor and a thermo-optic electrode. The position of the heating fixed resistor corresponds to the position of the waveguide core. The thermo-optic electrode is connected to the heating fixed resistor.

[0008] A piezoelectric modulation structure is located on the side of the waveguide core facing away from the substrate. The piezoelectric modulation structure includes a stacked first piezoelectric electrode, a piezoelectric thin film material layer, and a second piezoelectric electrode. The position of the piezoelectric thin film material layer corresponds to the position of the waveguide core. The first piezoelectric electrode also extends to the side of the piezoelectric thin film material layer.

[0009] The cladding covers the silicon photonic integrated circuit structure, the thermo-optical modulation structure, and the piezoelectric modulation structure, and exposes the thermo-optical electrode, part of the first piezoelectric electrode, and part of the second piezoelectric electrode.

[0010] The piezoelectric-thermo-optic composite modulator provided by this invention achieves thermo-optic modulation by aligning the position of the heating fixed resistor in the thermo-optic modulation structure with the position of the waveguide core. This offers advantages such as lower driving voltage for π phase shift, lower power consumption, and compatibility with CMOS technology. Furthermore, by aligning the position of the piezoelectric thin film material layer in the piezoelectric modulation structure with the position of the waveguide core, piezoelectric modulation can be achieved, resulting in high modulation speed and low power consumption. This piezoelectric-thermo-optic composite modulator integrates a piezoelectric modulator and a thermo-optic modulator in the same structure, enabling simultaneous hybrid modulation of piezoelectric and thermo-optic modulation. This reduces the driving voltage for π phase shift adjustment, achieving π phase shift adjustment at a lower voltage, increasing the modulation amplitude, and improving the modulation speed. Ultimately, this enhances the modulation efficiency and reliability of the composite modulator, reduces power consumption, and expands its application scenarios.

[0011] In one alternative implementation, the cladding includes a first cladding, a second cladding, and a third cladding;

[0012] The first cladding layer is located between the substrate layer and the thermo-optic modulation structure. The first cladding layer covers the side surface of the waveguide core facing away from the substrate layer and the side surface of the waveguide core.

[0013] The second cladding layer is located on the side surface of the first cladding layer facing away from the substrate layer; the second cladding layer covers the heating fixed resistor and the thermo-optic electrode; a third groove is provided on the side surface of the second cladding layer facing away from the substrate layer; the third groove exposes the side surface of the thermo-optic electrode facing away from the substrate layer.

[0014] The third cladding layer is located on the surface of the second cladding layer facing away from the first cladding layer; the third cladding layer covers the side surface and part of the surface of the first piezoelectric electrode, the piezoelectric thin film material layer, and the second piezoelectric electrode; the surface of the third cladding layer has a first groove and a second groove; the first groove exposes part of the surface of the first piezoelectric electrode; the second groove exposes part of the surface of the second piezoelectric electrode; the third groove also penetrates the third cladding layer;

[0015] The piezoelectric-thermo-optical composite modulator also includes a thermo-oxygen layer located between the substrate layer and the waveguide core.

[0016] In one alternative implementation, the piezoelectric modulation structure is located on the side of the thermo-optic modulation structure facing away from the waveguide core.

[0017] The projection position of the piezoelectric thin film material layer on the substrate and the projection position of the heating fixed resistor on the substrate cover the same area of ​​the same waveguide core on the substrate.

[0018] The piezoelectric-thermo-optic composite modulator provided by this invention allows the projection positions of the piezoelectric thin film material layer on the substrate and the projection positions of the heating fixed resistor on the substrate to cover the same region of the same waveguide core on the substrate. This enables π-phase shift adjustment based on the thermo-optic modulator for the same modulation region of the same optical waveguide, while simultaneously achieving high-speed modulation based on the piezoelectric modulator. π-phase shift adjustment can be achieved at a lower voltage, increasing the modulation amplitude and speed, thereby improving the modulation efficiency and reliability of the composite modulator, reducing its power consumption, and expanding its application scenarios.

[0019] In one alternative implementation, the waveguide core includes a first waveguide core and a second waveguide core;

[0020] The thermo-optic modulation structure is located on the side surface of the first cladding layer facing away from the first waveguide core; the projection position of the heating fixed resistor on the substrate layer covers part of the projection position of the first waveguide core on the substrate layer.

[0021] The piezoelectric modulation structure is located on the surface of the second cladding layer facing away from the second waveguide core; the projection position of the piezoelectric thin film material layer on the substrate layer covers part of the projection position of the second waveguide core on the substrate layer.

[0022] In one alternative implementation, the first waveguide core and the second waveguide core are different regions of the same waveguide core;

[0023] The projection position of the heating fixed resistor on the substrate does not coincide with the projection position of the piezoelectric thin film material layer on the substrate.

[0024] The piezoelectric-thermo-optic composite modulator provided by this invention has a first waveguide core and a second waveguide core that are different regions of the same waveguide core. The projection position of the heating fixed resistor on the substrate layer does not coincide with the projection position of the piezoelectric thin film material layer on the substrate layer. By acting on different regions of the same waveguide core with the thermo-optic modulator and the piezoelectric modulator respectively, thermo-optic modulation and piezoelectric modulation effects can be achieved on different modulation regions of the same optical waveguide according to requirements. This can increase the modulation amplitude, improve the modulation efficiency and reliability of the composite modulator, reduce the power consumption of the modulator, and expand the application scenarios of the modulator.

[0025] In one alternative implementation, a portion of the surface of the first piezoelectric electrode exposed by the first groove serves as a first pad.

[0026] The exposed portion of the surface of the first piezoelectric electrode in the first groove serves as the second pad.

[0027] The surface of the thermo-optical electrode exposed in the third groove is the third pad;

[0028] The first pad, the second pad, and the third pad are suitable for connecting an external power supply.

[0029] In one alternative implementation, the substrate layer is made of silicon;

[0030] The waveguide core is made of Si3N4; the thermal oxide layer is made of silicon dioxide.

[0031] The materials of the first cladding layer, the second cladding layer, and the third cladding layer are silicon dioxide;

[0032] The heating constant resistor is made of TiN; the thermo-optic electrode is made of AlCu.

[0033] The material of the piezoelectric thin film layer is aluminum nitride, lead zirconate titanate, hafnium oxide, zinc oxide or lithium niobate; the material of the first piezoelectric electrode is Mo, AlCu, Au, Ag or Pt; the material of the second piezoelectric electrode is Mo, AlCu, Au, Ag or Pt.

[0034] In one optional embodiment, the thickness of the substrate layer is 500 μm to 800 μm; the thickness of the thermo-oxidative layer is 2 μm to 8 μm; the thickness of the waveguide core is 0.075 μm to 0.45 μm; and the thickness of the first cladding layer is 0.5 μm to 2 μm.

[0035] The thickness of the heating fixed resistor is 0.05μm to 0.15μm; the thickness of the thermo-optical electrode is 0.5μm to 1.5μm.

[0036] The thickness of the second cladding layer is 0.5 μm to 1.5 μm;

[0037] The thickness of the piezoelectric thin film material layer is 0.8 μm to 1.5 μm; the thickness of the first piezoelectric electrode is 0.1 μm to 0.2 μm; and the thickness of the second piezoelectric electrode is 0.1 μm to 0.2 μm.

[0038] In one alternative implementation, the driving voltage for the π phase shift of the piezoelectric-thermo-optic composite modulator is less than 10V; the modulation speed is greater than 1GHz.

[0039] The piezoelectric-thermo-optic composite modulator provided by this invention integrates a piezoelectric modulator and a thermo-optic modulator in the same structure, enabling a hybrid modulation method of piezoelectric modulation and thermo-optic modulation. The driving voltage of the π phase shift of the piezoelectric-thermo-optic composite modulator is less than 10V, and the modulation speed is greater than 1GHz. It can achieve π phase shift adjustment at a lower voltage, increase the modulation amplitude, improve the modulation speed, thereby improving the modulation efficiency and reliability of the composite modulator, reducing the power consumption of the modulator, and expanding the application scenarios of the modulator.

[0040] In a second aspect, the present invention provides a method for fabricating a piezoelectric-thermo-optic composite modulator, used to fabricate the piezoelectric-thermo-optic composite modulator described in the first aspect above, the method comprising:

[0041] A silicon photonic integrated circuit structure is provided, which includes a substrate layer and a waveguide core located on one side of the substrate layer;

[0042] A thermo-optic modulation structure is formed on the side of the waveguide core facing away from the substrate. The thermo-optic modulation structure includes a heating fixed resistor and a thermo-optic electrode. The position of the heating fixed resistor corresponds to the position of the waveguide core. The thermo-optic electrode is connected to the heating fixed resistor.

[0043] A piezoelectric modulation structure is formed on the side of the waveguide core facing away from the substrate. The piezoelectric modulation structure includes a stacked first piezoelectric electrode, a piezoelectric thin film material layer, and a second piezoelectric electrode. The position of the piezoelectric thin film material layer corresponds to the position of the waveguide core. The first piezoelectric electrode also extends to the side of the piezoelectric thin film material layer.

[0044] A cladding layer is formed, which covers the silicon photonic integrated circuit structure, the thermo-optic modulation structure, and the piezoelectric modulation structure, and exposes the thermo-optic electrode, part of the first piezoelectric electrode, and part of the second piezoelectric electrode.

[0045] The piezoelectric-thermo-optic composite modulator fabrication method provided by this invention has the following advantages: First, the position of the heating fixed resistor in the formed thermo-optic modulation structure corresponds to the position of the waveguide core, enabling thermo-optic modulation with advantages such as low driving voltage for π phase shift, low power consumption, and compatibility with CMOS technology. Second, the position of the piezoelectric thin film material layer in the formed piezoelectric modulation structure corresponds to the position of the waveguide core, enabling piezoelectric modulation with high modulation speed and low power consumption. Third, the simultaneous formation of a first groove, a second groove, and a third groove allows for the simultaneous extraction of electrodes from both the thermo-optic and piezoelectric modulation structures, simplifying the process flow and improving process efficiency. This method, by forming piezoelectric and thermo-optic modulation structures in different structural layers of the modulator, enables a hybrid modulation mode combining piezoelectric and thermo-optic modulation. It allows for π phase shift adjustment at a lower voltage, increasing the modulation amplitude and speed, thereby improving the modulation efficiency and reliability of the composite modulator, reducing power consumption, expanding its application scenarios, and simultaneously extracting electrodes from both structures, simplifying the process flow and improving process efficiency.

[0046] In one alternative implementation, the step of forming the cladding includes:

[0047] After the step of providing the silicon photonic integrated circuit structure and before the step of forming the thermo-optical modulation structure, a first cladding layer is formed on one side of the substrate layer; the first cladding layer covers the side surface of the waveguide core facing away from the substrate layer and the side surface of the waveguide core;

[0048] After the step of forming the first cladding layer and before the step of forming the piezoelectric modulation structure, a second cladding layer is formed on the side surface of the first cladding layer facing away from the substrate layer. The second cladding layer covers the heating fixed resistor and the thermo-optical electrode.

[0049] After the step of forming the piezoelectric modulation structure, a third cladding layer is formed on the surface of the second cladding layer opposite to the first cladding layer. The third cladding layer covers the surface and side of the first piezoelectric electrode, the piezoelectric thin film material layer, and the second piezoelectric electrode.

[0050] A first groove, a second groove, and a third groove are formed on the side surface of the third cladding layer facing away from the first cladding layer; the first groove exposes a portion of the surface of the first piezoelectric electrode; the second groove exposes a portion of the surface of the second piezoelectric electrode; the third groove penetrates the third cladding layer and extends into the second cladding layer, exposing the side surface of the thermo-optical electrode facing away from the substrate layer.

[0051] In one alternative embodiment, in the step of forming the first groove, the second groove, and the third groove on the side surface of the third cladding layer facing away from the first cladding layer,

[0052] A first pad is formed on the surface of the first piezoelectric electrode exposed by the first groove, a second pad is formed on the surface of the second piezoelectric electrode exposed by the second groove, and a third pad is formed on the surface of the thermo-optical electrode exposed by the third groove. Attached Figure Description

[0053] To more clearly illustrate the technical solutions in the specific embodiments or related technologies of the present invention, the drawings used in the description of the specific embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0054] Figure 1 This is a schematic diagram of a piezoelectric-thermo-optic composite modulator according to an embodiment of the present invention.

[0055] Figure 2 This is a schematic diagram of another piezoelectric-thermo-optic composite modulator according to an embodiment of the present invention.

[0056] Figure 3 This is a schematic flowchart of a method for fabricating a piezoelectric-thermo-optic composite modulator according to an embodiment of the present invention.

[0057] Figure 4 This is a schematic diagram illustrating the specific process of a method for fabricating a piezoelectric-thermo-optic composite modulator according to an embodiment of the present invention.

[0058] Figure 5 This is a schematic diagram of the structure forming the thermo-optic modulation structure in a method for preparing a piezoelectric-thermo-optic composite modulator according to an embodiment of the present invention.

[0059] Figure 6 This is a schematic diagram of the structure of a silicon photonic integrated circuit formed in a method for fabricating a piezoelectric-thermo-optical composite modulator according to an embodiment of the present invention.

[0060] Figure 7 This is a schematic diagram of the piezoelectric modulation structure formed in a method for fabricating a piezoelectric-thermo-optic composite modulator according to an embodiment of the present invention.

[0061] Figure label:

[0062] 10. Waveguide core; 11. First cladding; 12. Thermo-oxidative layer; 13. Substrate layer; 21. Heating fixed resistor; 22. Second cladding; 23. Thermo-optic electrode; 31. First piezoelectric electrode; 32. Piezoelectric thin film material layer; 33. Second piezoelectric electrode; 34. Third cladding. Detailed Implementation

[0063] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the invention, not the entire structure.

[0064] In the following description, descriptions of well-known structures and techniques are omitted to avoid unnecessarily obscuring the concepts of the present invention. Various structural schematic diagrams according to embodiments of the present invention are shown in the accompanying drawings. These drawings are not to scale, and some details are enlarged for clarity, and some details may be omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed. In the context of the present invention, when a layer / element is referred to as being "on" another layer / element, the layer / element may be directly on the other layer / element, or there may be an intermediate layer / element between them. Additionally, if a layer / element is "on" another layer / element in one orientation, then when the orientation is reversed, the layer / element may be "below" the other layer / element.

[0065] Silicon nitride (SiN) is characterized by low loss and compatibility with CMOS processes, enabling the realization of high-performance passive devices. However, it lacks monolithically integrated high-speed devices, such as optical modulators. In integrated silicon-based optoelectronic chips, optical modulators can control the phase of light waves by changing the refractive index of the waveguide, thereby achieving chip function modulation. Among them, thermo-optic modulators are compatible with CMOS processes and can adjust the optical properties of waveguides by changing the temperature of the waveguide material. They play an important role in silicon photonic devices. Thermo-optic modulators can be used to achieve phase modulation, amplitude modulation, and polarization modulation of light beams, and are characterized by low power consumption and easy integration. However, their response time is generally on the order of microseconds (μs), and their modulation speed is relatively slow (~kHz). Piezoelectric modulators based on the inverse piezoelectric effect are also an important modulation device. When an external electric field is applied to a crystal material, the crystal material deforms. If the crystal material is combined with an optical waveguide, the stress of the crystal material deformation is transferred to the optical waveguide, thereby changing the refractive index of the optical waveguide. Compared to thermo-optic modulators, piezoelectric modulators can reduce power consumption by 3-5 orders of magnitude and also feature high modulation speeds (~GHz). However, they also suffer from issues such as high driving voltage and incompatibility with CMOS processes.

[0066] Current research on silicon nitride chip modulators is relatively limited. On silicon nitride photonic integration platforms, it is difficult to integrate modulators with different materials and properties in terms of process technology, especially for modulation of the same modulation region of the same waveguide. There is a lack of composite modulators that integrate modulators with different modulation characteristics in terms of process technology.

[0067] Therefore, a composite modulator is needed that combines the advantages of thermo-optic modulators, such as low driving voltage, low power consumption, and compatibility with CMOS technology, to achieve π-phase shift, with the advantages of piezoelectric modulators, such as high modulation speed and low power consumption.

[0068] like Figure 1 As shown, this embodiment provides a piezoelectric-thermo-optic composite modulator, which includes:

[0069] A silicon photonic integrated circuit structure, including a substrate layer 13 and a waveguide core 10 located on one side of the substrate layer 13;

[0070] The thermo-optic modulation structure is located on the side of the waveguide core 10 facing away from the substrate layer 13; the thermo-optic modulation structure includes a heating fixed resistor 21 and a thermo-optic electrode 23; the position of the heating fixed resistor 21 corresponds to the position of the waveguide core 10; the thermo-optic electrode 23 is connected to the heating fixed resistor 21.

[0071] The piezoelectric modulation structure is located on the side of the waveguide core 10 facing away from the substrate layer 13. The piezoelectric modulation structure includes a first piezoelectric electrode 31, a piezoelectric thin film material layer 32, and a second piezoelectric electrode 33 stacked together. The position of the piezoelectric thin film material layer 32 corresponds to the position of the waveguide core 10. The first piezoelectric electrode 31 also extends to the side of the piezoelectric thin film material layer 32.

[0072] The cladding layer covers the silicon photonic integrated circuit structure, the thermo-optic modulation structure, and the piezoelectric modulation structure, and exposes the thermo-optic electrodes, part of the first piezoelectric electrode, and part of the second piezoelectric electrode. Specifically, the position of the heating fixed resistor 21 corresponds to the position of the thermo-optic modulation region of the waveguide core 10; the position of the piezoelectric thin film material layer 32 corresponds to the position of the electro-optic modulation region of the waveguide core 10. The thermo-optic modulation region and the electro-optic modulation region can be the same region or different regions.

[0073] The piezoelectric-thermo-optic composite modulator provided in this embodiment achieves thermo-optic modulation by aligning the position of the heating fixed resistor in the thermo-optic modulation structure with the position of the waveguide core. This offers advantages such as lower driving voltage for π phase shift, lower power consumption, and compatibility with CMOS technology. Furthermore, by aligning the position of the piezoelectric thin film material layer in the piezoelectric modulation structure with the position of the waveguide core, piezoelectric modulation can be achieved, resulting in high modulation speed and low power consumption. This piezoelectric-thermo-optic composite modulator integrates a piezoelectric modulator and a thermo-optic modulator in the same structure, enabling a hybrid modulation method that reduces the driving voltage for π phase shift adjustment. This allows for π phase shift adjustment at a lower voltage, increasing the modulation amplitude and speed, thereby improving the modulation efficiency and reliability of the composite modulator, reducing power consumption, and expanding its application scenarios.

[0074] In some alternative implementations, the cladding includes a first cladding 11, a second cladding 22, and a third cladding 34;

[0075] The first cladding layer 11 is located between the substrate layer 13 and the thermo-optic modulation structure. The first cladding layer 11 covers the side surface of the waveguide core 10 facing away from the substrate layer 13 and the side surface of the waveguide core 10.

[0076] The second cladding layer 22 is located on the side surface of the first cladding layer 11 facing away from the substrate layer 13; the second cladding layer 22 covers the heating fixed resistor 21 and the thermo-optical electrode 23; a third groove is provided on the side of the second cladding layer 22 facing away from the substrate layer 13; the third groove exposes the side surface of the thermo-optical electrode 23 facing away from the substrate layer 13.

[0077] The third cladding layer 34 is located on the surface of the second cladding layer 22 facing away from the first cladding layer 11; the third cladding layer 34 covers the side surface and part of the surface of the first piezoelectric electrode 31, the piezoelectric thin film material layer 32, and the second piezoelectric electrode 33; the surface of the third cladding layer 34 has a first groove and a second groove; the first groove exposes part of the surface of the first piezoelectric electrode 31; the second groove exposes part of the surface of the second piezoelectric electrode 33; the third groove also penetrates the third cladding layer 34;

[0078] The piezoelectric-thermo-optical composite modulator also includes a thermo-oxygen layer 12, located between the substrate layer 13 and the waveguide core 10.

[0079] In some alternative implementations, the piezoelectric modulation structure is located on the side of the thermo-optic modulation structure opposite to the waveguide core 10;

[0080] The projection position of the piezoelectric thin film material layer 32 on the substrate layer 13 and the projection position of the heating fixed resistor 21 on the substrate layer 13 cover the same area of ​​the waveguide core 10 on the substrate layer 13.

[0081] The piezoelectric-thermo-optic composite modulator provided in this embodiment has a projection position of the piezoelectric thin film material layer on the substrate layer and a projection position of the heating fixed resistor on the substrate layer covering the same region of the same waveguide core on the substrate layer. This allows for π-phase shift adjustment based on the thermo-optic modulator in the same modulation region of the same optical waveguide, while simultaneously achieving high-speed modulation based on the piezoelectric modulator. π-phase shift adjustment can be achieved at a lower voltage, increasing the modulation amplitude and speed, thereby improving the modulation efficiency and reliability of the composite modulator, reducing the modulator's power consumption, and expanding the modulator's application scenarios.

[0082] In some alternative implementations, such as Figure 2 As shown, the waveguide core 10 includes a first waveguide core 101 and a second waveguide core 102;

[0083] The thermo-optic modulation structure is located on the side surface of the first cladding 11 facing away from the first waveguide core 101; the projection position of the heating fixed resistor 21 on the substrate 13 covers part of the projection position of the first waveguide core 101 on the substrate 13.

[0084] The piezoelectric modulation structure is located on the side surface of the second cladding 22 facing away from the second waveguide core 102; the projection position of the piezoelectric thin film material layer 32 on the substrate layer 13 covers part of the projection position of the second waveguide core 102 on the substrate layer 13.

[0085] In some alternative implementations, such as Figure 2 As shown, the first waveguide core 101 and the second waveguide core 102 are different regions of the same waveguide core 10;

[0086] The projection position of the heating fixed resistor on the substrate 13 does not coincide with the projection position of the piezoelectric thin film material layer 32 on the substrate 13.

[0087] The piezoelectric-thermo-optic composite modulator provided in this embodiment has a first waveguide core and a second waveguide core that are different regions of the same waveguide core. The projection position of the heating fixed resistor on the substrate layer does not coincide with the projection position of the piezoelectric thin film material layer on the substrate layer. By acting on different regions of the same waveguide core with the thermo-optic modulator and the piezoelectric modulator respectively, thermo-optic modulation and piezoelectric modulation effects can be achieved on different modulation regions of the same optical waveguide according to requirements. This can increase the modulation amplitude, improve the modulation efficiency and reliability of the composite modulator, reduce the power consumption of the modulator, and expand the application scenarios of the modulator.

[0088] In some alternative implementations, the first waveguide core 101 and the second waveguide core 102 are two different waveguide cores;

[0089] The projection position of the heating fixed resistor on the substrate 13 does not coincide with the projection position of the piezoelectric thin film material layer 32 on the substrate 13.

[0090] In some alternative embodiments, a portion of the surface of the first piezoelectric electrode 31 exposed by the first groove is a first pad;

[0091] The exposed portion of the surface of the first piezoelectric electrode 31 in the first groove is the second pad;

[0092] The surface of the exposed thermo-optical electrode 23 in the third groove is the third pad;

[0093] The first, second, and third pads are suitable for connecting an external power supply.

[0094] In some alternative embodiments, the substrate 13 is made of silicon;

[0095] The waveguide core 10 is made of Si3N4 or other waveguide materials; the thermal oxide layer 12 is made of silicon dioxide; the waveguide core 10 can be selected from one of the various waveguide structures or composite waveguide structures in the prior art (such as ridge waveguide); the first cladding 11, the second cladding 22 and the third cladding 34 are made of silicon dioxide.

[0096] The heating fixed resistor 21 is made of TiN; the thermo-optic electrode 23 is made of AlCu.

[0097] The material of the piezoelectric thin film material layer 32 is aluminum nitride, lead zirconate titanate, hafnium oxide, zinc oxide or lithium niobate; the material of the first piezoelectric electrode 31 is Mo, AlCu, Au, Ag or Pt; the material of the second piezoelectric electrode 33 is Mo, AlCu, Au, Ag or Pt.

[0098] In some alternative embodiments, the thickness of the substrate layer 13 is 500 μm to 800 μm, for example, 500 μm, 600 μm, 700 μm and 800 μm; the thickness of the thermal oxide layer 12 is 2 μm to 8 μm, for example, 2 μm, 4 μm, 5 μm, 6 μm and 8 μm; the thickness of the waveguide core 10 is 0.075 μm to 0.45 μm, for example, 0.075 μm, 0.1 μm, 0.2 μm, 0.3 μm and 0.45 μm; and the thickness of the first cladding layer 11 is 0.5 μm to 2 μm, for example, 0.5 μm, 0.85 μm, 1.25 μm, 1.5 μm and 2 μm.

[0099] The thickness of the heating fixed resistor 21 is 0.05μm to 0.15μm; the thickness of the thermo-optical electrode 23 is 0.5μm to 1.5μm, for example 0.5μm, 0.75μm, 1μm, 1.25μm and 1.5μm;

[0100] The thickness of the second cladding 22 is 0.5 μm to 1.5 μm, for example, 0.5 μm, 0.75 μm, 1 μm, 1.25 μm and 1.5 μm;

[0101] The thickness of the piezoelectric thin film material layer 32 is 0.8 μm to 1.5 μm, for example, 0.8 μm, 1.1 μm, 1.15 μm, 1.3 μm and 1.5 μm; the thickness of the first piezoelectric electrode 31 is 0.1 μm to 0.2 μm, for example, 0.1 μm, 0.12 μm, 0.15 μm, 0.18 μm and 0.2 μm; the thickness of the second piezoelectric electrode 33 is 0.1 μm to 0.2 μm, for example, 0.1 μm, 0.12 μm, 0.15 μm, 0.18 μm and 0.2 μm.

[0102] In some alternative implementations, the driving voltage for the π phase shift of the piezoelectric-thermo-optic composite modulator is less than 10V; the modulation speed is greater than 1GHz.

[0103] The piezoelectric-thermo-optic composite modulator provided in this embodiment integrates a piezoelectric modulator and a thermo-optic modulator in the same structure, enabling a hybrid modulation method of piezoelectric modulation and thermo-optic modulation. The driving voltage of the π phase shift of the piezoelectric-thermo-optic composite modulator is less than 10V, and the modulation speed is greater than 1GHz. It can achieve π phase shift adjustment at a lower voltage, increase the modulation amplitude, improve the modulation speed, thereby improving the modulation efficiency and reliability of the composite modulator, reducing the power consumption of the modulator, and expanding the application scenarios of the modulator.

[0104] like Figure 3 As shown, this embodiment provides a method for fabricating a piezoelectric-thermo-optical composite modulator, which includes, but is not limited to, steps S101 to S106.

[0105] Step S101: Provide a silicon photonic integrated circuit structure, a silicon photonic integrated circuit structure substrate 13 and a waveguide core 10 located on one side of the substrate 13.

[0106] In step S102, a thermo-optic modulation structure is formed on the side of the waveguide core 10 facing away from the substrate layer 13. The thermo-optic modulation structure includes a heating fixed resistor 21 and a thermo-optic electrode 23. The position of the heating fixed resistor 21 corresponds to the position of the waveguide core 10. The thermo-optic electrode 23 is connected to the heating fixed resistor 21.

[0107] In step S103, a piezoelectric modulation structure is formed on the side of the waveguide core 10 facing away from the substrate layer 13. The piezoelectric modulation structure includes a first piezoelectric electrode 31, a piezoelectric thin film material layer 32, and a second piezoelectric electrode 33 stacked together. The position of the piezoelectric thin film material layer 32 corresponds to the position of the waveguide core 10. The first piezoelectric electrode 31 also extends to the side of the piezoelectric thin film material layer 32.

[0108] Step S104: A cladding layer is formed, which covers the silicon photonic integrated circuit structure, the thermo-optical modulation structure and the piezoelectric modulation structure, and exposes the thermo-optical electrode 23, a portion of the first piezoelectric electrode 31 and a portion of the second piezoelectric electrode 33.

[0109] In some alternative implementations, the step of forming the cladding includes:

[0110] After the step of providing the silicon photonic integrated circuit structure and before the step of forming the thermo-optical modulation structure, a first cladding layer 11 is formed on one side of the substrate layer 13; the first cladding layer 11 covers the side surface of the waveguide core 10 facing away from the substrate layer 13 and the side surface of the waveguide core 10.

[0111] After the step of forming the first cladding layer 11 and before the step of forming the piezoelectric modulation structure, a second cladding layer 22 is formed on the side surface of the first cladding layer 11 facing away from the substrate layer 13. The second cladding layer 22 covers the heating fixed resistor 21 and the thermo-optical electrode 23.

[0112] After the step of forming the piezoelectric modulation structure, a third cladding layer 34 is formed on the surface of the second cladding layer 22 facing away from the first cladding layer 11. The third cladding layer 34 covers the surface and side of the first piezoelectric electrode 31, the piezoelectric thin film material layer 32, and the second piezoelectric electrode 33.

[0113] A first groove, a second groove, and a third groove are formed on the surface of the third cladding 34 facing away from the first cladding 11; the first groove exposes a portion of the surface of the first piezoelectric electrode 31; the second groove exposes a portion of the surface of the second piezoelectric electrode 33; the third groove penetrates the third cladding 34 and extends into the second cladding 22, exposing the surface of the thermo-optical electrode 23 facing away from the substrate layer 13.

[0114] like Figure 4 As shown in the figure, this embodiment provides a specific flowchart of a method for fabricating a piezoelectric-thermo-optic composite modulator, which includes, but is not limited to, steps S201 to S206.

[0115] Step S201: Provide a silicon photonics integrated circuit structure, which includes a stacked substrate layer 13, a thermal oxide layer 12, a waveguide core 10, and a first cladding layer 11; the first cladding layer 11 covers the side surface of the waveguide core 10 facing away from the substrate layer 13 and the side surface of the waveguide core 10, such as... Figure 5 As shown.

[0116] In specific implementation, the substrate 13 is made of silicon, the waveguide core 10 is made of Si3N4 or TriPleX, the thermal oxide layer 12 is made of silicon dioxide, and the first cladding layer 11 is made of silicon dioxide; the thickness of the substrate 13 is 500μm to 800μm, the thickness of the thermal oxide layer 12 is 2μm to 8μm, and the thickness of the first cladding layer 11 is 0.5μm to 2μm.

[0117] In step S202, a thermo-optical modulation structure is formed on the surface of the first cladding 11 facing away from the waveguide core 10; the thermo-optical modulation structure includes a heating fixed resistor 21 and a thermo-optical electrode 23; the position of the heating fixed resistor 21 corresponds to the position of the waveguide core 10; the thermo-optical electrode 23 is connected to the heating fixed resistor 21, such as... Figure 6 As shown.

[0118] In a specific implementation, a heating fixed resistor 21 and a side-mounted thermo-optical electrode 23 are formed on the surface of the first cladding 11 corresponding to the thermo-optical modulation region of the waveguide core 10, facing away from the waveguide core 10. A specific morphology is obtained through patterning. The heating fixed resistor 21 is located above the thermo-optical modulation region of the waveguide core 10, forming a thermo-optical modulation structure. The thermo-optical electrode 23 is located on the side of the heating fixed resistor 21 and is electrically connected to it.

[0119] The heating fixed resistor 21 is made of TiN, and the thermo-optical electrode 23 is made of AlCu; the thickness of the heating fixed resistor 21 is 0.05μm to 0.15μm, and the thickness of the thermo-optical electrode 23 is 0.5μm to 1.5μm.

[0120] In step S203, a second cladding layer 22 is formed on the side of the first cladding layer 11 facing away from the substrate layer 13. The second cladding layer 22 covers the heating fixed resistor 21 and the thermo-optical electrode 23, as shown below. Figure 6 As shown.

[0121] In a specific implementation, a second cladding layer 22 is deposited on the surface of the first cladding layer 11 facing away from the substrate layer 13. The material of the second cladding layer 22 is silicon dioxide, and the thickness of the second cladding layer 22 is 0.5 μm to 1.5 μm. The second cladding layer can cover and protect the thermo-optical modulation structure, improving the reliability of the modulator.

[0122] Step S204: A piezoelectric modulation structure is formed on the surface of the second cladding 22 facing away from the waveguide core 10. The piezoelectric modulation structure includes a stacked first piezoelectric electrode 31, a piezoelectric thin film material layer 32, and a second piezoelectric electrode 33. The position of the piezoelectric thin film material layer 32 corresponds to the position of the waveguide core 10. The first piezoelectric electrode 31 also extends to the side of the piezoelectric thin film material layer 32, such as... Figure 7 As shown.

[0123] In specific implementation, a first piezoelectric electrode 31, a piezoelectric thin film material layer 32, and a second piezoelectric electrode 33 are stacked on the surface of the second cladding 22 corresponding to the electro-optic modulation region of the waveguide core 10 on the side away from the waveguide core 10. The first piezoelectric electrode 31, the piezoelectric thin film material layer 32, and the second piezoelectric electrode 33 are patterned and etched in sequence to obtain a specific morphology, such that the piezoelectric thin film material layer 32 is above the electro-optic modulation region of the waveguide core 10, and the first piezoelectric electrode 31 also extends to the side of the piezoelectric thin film material layer 32 to form a piezoelectric modulation structure.

[0124] The piezoelectric thin film material layer 32 is made of aluminum nitride or lead zirconate titanate; the first piezoelectric electrode 31 is made of Mo, AlCu, Au, Ag, or Pt; and the second piezoelectric electrode 33 is made of Mo, AlCu, Au, Ag, or Pt. The materials of the first piezoelectric electrode 31 and the second piezoelectric electrode 33 can be the same or different.

[0125] In step S205, a third cladding layer 34 is formed on the surface of the second cladding layer 22 facing away from the first cladding layer 11. The third cladding layer 34 covers the surface and side surfaces of the first piezoelectric electrode 31, the piezoelectric thin film material layer 32, and the second piezoelectric electrode 33, as shown below. Figure 7 As shown.

[0126] In a specific implementation, a third cladding layer 34 is deposited on the surface of the second cladding layer 22 facing away from the first cladding layer 11. The material of the third cladding layer 34 is silicon dioxide, and the thickness of the third cladding layer 34 is 0.5 μm to 1.5 μm. The third cladding layer 34 can cover and protect the thermo-optical modulation structure, improving the reliability of the modulator.

[0127] In step S206, a first groove, a second groove, and a third groove are formed on the surface of the third cladding layer 34 facing away from the first cladding layer 11; the first groove exposes a portion of the surface of the first piezoelectric electrode 31; the second groove exposes a portion of the surface of the second piezoelectric electrode 33; the third groove penetrates the third cladding layer 34 and extends into the second cladding layer 22, exposing the surface of the thermo-optical electrode 23 facing away from the substrate layer 13, as shown below. Figure 7 As shown.

[0128] In specific implementation, by etching the third cladding layer 34 and the second cladding layer 22, the first groove, the second groove and the third groove are formed simultaneously, exposing part of the surface of the first piezoelectric electrode 31, part of the surface of the second piezoelectric electrode 33 and the side surface of the thermo-optical electrode 23 facing away from the substrate layer 13, respectively; the electrodes of the thermo-optical modulation structure and the piezoelectric modulation structure can be brought out at the same time, simplifying the process flow and improving the process efficiency.

[0129] The fabrication method of the piezoelectric-thermo-optic composite modulator provided in this embodiment has several advantages. Firstly, the position of the heating fixed resistor in the formed thermo-optic modulation structure corresponds to the position of the waveguide core, enabling thermo-optic modulation. This method offers advantages such as lower driving voltage for π phase shift, lower power consumption, and compatibility with CMOS technology. Secondly, the position of the piezoelectric thin film material layer in the formed piezoelectric modulation structure corresponds to the position of the waveguide core, enabling piezoelectric modulation with high modulation speed and low power consumption. Thirdly, the simultaneous formation of the first, second, and third grooves allows for the simultaneous extraction of electrodes from both the thermo-optic and piezoelectric modulation structures, simplifying the process and improving efficiency. This method, by forming piezoelectric and thermo-optic modulation structures in different structural layers of the modulator, enables a hybrid modulation method combining piezoelectric and thermo-optic modulation. It allows for π phase shift adjustment at lower voltages, increasing modulation amplitude and speed, thereby improving the modulation efficiency and reliability of the composite modulator, reducing power consumption, expanding its application scenarios, and simultaneously extracting electrodes from both structures, further simplifying the process and improving efficiency.

[0130] In some alternative embodiments, in the step of forming the first groove, the second groove, and the third groove on the surface of the third cladding 34 opposite to the first cladding 11,

[0131] A first pad is formed on the surface of the first piezoelectric electrode 31 exposed by the first groove, a second pad is formed on the surface of the second piezoelectric electrode 33 exposed by the second groove, and a third pad is formed on the surface of the thermo-optical electrode 23 exposed by the third groove.

[0132] In practical implementation, the first and second pads forming the piezoelectric modulation structure, and the third pad forming the thermo-optic modulation structure, are exposed through the first, second, and third grooves, respectively. This allows for the simultaneous extraction of electrodes from both the thermo-optic and piezoelectric modulation structures, simplifying the process and improving efficiency. External leads connected to the first, second, and third pads connect the external circuitry to the first piezoelectric electrode 31, the second piezoelectric electrode 33, and the thermo-optic electrode 23, enabling the driving and control of the thermo-optic modulator and the piezoelectric modulator. This further simplifies the process and improves efficiency.

[0133] In the description of this specification, the references to terms such as "this embodiment," "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, those skilled in the art can combine and integrate the different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of the present invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0134] The above description does not provide detailed explanations of the technical aspects of each layer's patterning, etching, etc. However, those skilled in the art should understand that various technical means can be used to form layers and regions of the desired shape. Furthermore, to form the same structure, those skilled in the art can also design methods that are not entirely identical to those described above. Additionally, although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination.

[0135] The above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described above, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention. The scope of protection of the present invention is determined by the scope of the appended claims.

Claims

1. A piezoelectric-thermo-optic composite modulator, characterized in that, include: A silicon photonic integrated circuit structure, including a substrate layer and a waveguide core located on one side of the substrate layer; A thermo-optic modulation structure is located on the side of the waveguide core facing away from the substrate layer; The thermo-optic modulation structure includes a heating fixed resistor and a thermo-optic electrode; The position of the heating fixed resistor corresponds to the position of the waveguide core; The thermo-optic electrode is connected to the heating fixed resistor; A piezoelectric modulation structure is located on the side of the waveguide core facing away from the substrate layer; The piezoelectric modulation structure includes a stacked first piezoelectric electrode, a piezoelectric thin film material layer, and a second piezoelectric electrode; the position of the piezoelectric thin film material layer corresponds to the position of the waveguide core; the first piezoelectric electrode also extends to the side of the piezoelectric thin film material layer. The cladding covers the silicon photonic integrated circuit structure, the thermo-optic modulation structure and the piezoelectric modulation structure, and exposes the thermo-optic electrode, a portion of the first piezoelectric electrode and a portion of the second piezoelectric electrode.

2. The piezoelectric-thermo-optic composite modulator according to claim 1, characterized in that, The cladding includes a first cladding, a second cladding, and a third cladding; A first cladding layer is located between the substrate layer and the thermo-optic modulation structure, and the first cladding layer covers the side surface of the waveguide core facing away from the substrate layer and the side surface of the waveguide core; The second cladding layer is located on the side surface of the first cladding layer that faces away from the substrate layer; The second cladding layer covers the heating fixed resistor and the thermo-optical electrode; The second cladding layer has a third groove on the side facing away from the substrate layer; the third groove exposes the surface of the thermo-optic electrode facing away from the substrate layer. The third cladding layer is located on the surface of the second cladding layer that faces away from the first cladding layer; The third cladding layer covers the side surfaces and part of the surface of the first piezoelectric electrode, the piezoelectric thin film material layer, and the second piezoelectric electrode; the surface of the third cladding layer has a first groove and a second groove; the first groove exposes part of the surface of the first piezoelectric electrode; The second groove exposes a portion of the surface of the second piezoelectric electrode; The third groove also penetrates the third cladding layer; The piezoelectric-thermo-optical composite modulator further includes a thermo-oxygen layer located between the substrate layer and the waveguide core.

3. The piezoelectric-thermo-optic composite modulator according to claim 1, characterized in that, The piezoelectric modulation structure is located on the side of the thermo-optic modulation structure opposite to the waveguide core; The projection position of the piezoelectric thin film material layer on the substrate and the projection position of the heating fixed resistor on the substrate cover the same area of ​​the waveguide core on the substrate.

4. The piezoelectric-thermo-optic composite modulator according to claim 1, characterized in that, The waveguide core includes a first waveguide core and a second waveguide core; The thermo-optic modulation structure is located on the side surface of the first waveguide core facing away from the substrate; the projection position of the heating fixed resistor on the substrate covers part of the projection position of the first waveguide core on the substrate. The piezoelectric modulation structure is located on the side surface of the second waveguide core facing away from the substrate layer; The projection position of the piezoelectric thin film material layer on the substrate layer covers part of the projection position of the second waveguide core on the substrate layer.

5. The piezoelectric-thermo-optic composite modulator according to claim 4, characterized in that, The first waveguide core and the second waveguide core are different regions of the same waveguide core; The projection position of the heating fixed resistor on the substrate layer does not coincide with the projection position of the piezoelectric thin film material layer on the substrate layer.

6. The piezoelectric-thermo-optic composite modulator according to claim 2, characterized in that, The exposed portion of the surface of the first piezoelectric electrode in the first groove is the first pad; The exposed portion of the surface of the first piezoelectric electrode in the first groove serves as the second pad; The surface of the thermo-optical electrode exposed by the third groove is the third pad; The first pad, the second pad, and the third pad are adapted to connect to an external power source.

7. The piezoelectric-thermo-optic composite modulator according to claim 2, characterized in that, The substrate layer is made of silicon. The waveguide core is made of Si3N4; The material of the thermo-oxidative layer is silicon dioxide; The first, second, and third cladding layers are made of silicon dioxide; The heating constant resistor is made of TiN; the thermo-optic electrode is made of AlCu. The material of the piezoelectric thin film layer is aluminum nitride, lead zirconate titanate, hafnium oxide, zinc oxide or lithium niobate; the material of the first piezoelectric electrode is Mo, AlCu, Au, Ag or Pt; the material of the second piezoelectric electrode is Mo, AlCu, Au, Ag or Pt.

8. The piezoelectric-thermo-optic composite modulator according to claim 2, characterized in that, The thickness of the substrate layer is 500 μm to 800 μm; the thickness of the thermo-oxidative layer is 2 μm to 8 μm; the thickness of the waveguide core is 0.075 μm to 0.45 μm; and the thickness of the first cladding layer is 0.5 μm to 2 μm. The thickness of the heating fixed resistor is 0.05μm to 0.15μm; the thickness of the thermo-optical electrode is 0.5μm to 1.5μm. The thickness of the second cladding layer is 0.5 μm to 1.5 μm; The thickness of the piezoelectric thin film material layer is 0.8 μm to 1.5 μm; the thickness of the first piezoelectric electrode is 0.1 μm to 0.2 μm; and the thickness of the second piezoelectric electrode is 0.1 μm to 0.2 μm.

9. The piezoelectric-thermo-optic composite modulator according to claim 1, characterized in that, The driving voltage for the π phase shift of the piezoelectric-thermo-optic composite modulator is less than 10V; the modulation speed is greater than 1GHz.

10. A method for fabricating a piezoelectric-thermo-optic composite modulator, characterized in that, include: A silicon photonic integrated circuit structure is provided, the silicon photonic integrated circuit structure including a substrate layer and a waveguide core located on one side of the substrate layer; A thermo-optic modulation structure is formed on the side of the waveguide core facing away from the substrate; the thermo-optic modulation structure includes a heating fixed resistor and a thermo-optic electrode. The position of the heating fixed resistor corresponds to the position of the waveguide core; The thermo-optic electrode is connected to the heating fixed resistor; A piezoelectric modulation structure is formed on the side of the waveguide core facing away from the substrate layer; The piezoelectric modulation structure includes a stacked first piezoelectric electrode, a piezoelectric thin film material layer, and a second piezoelectric electrode; the position of the piezoelectric thin film material layer corresponds to the position of the waveguide core; the first piezoelectric electrode also extends to the side of the piezoelectric thin film material layer. A cladding layer is formed, which covers the silicon photonic integrated circuit structure, the thermo-optic modulation structure and the piezoelectric modulation structure, and exposes the thermo-optic electrode, a portion of the first piezoelectric electrode and a portion of the second piezoelectric electrode.

11. The method for preparing the piezoelectric-thermo-optic composite modulator according to claim 10, characterized in that, The step of forming the cladding includes: After the step of providing the silicon photonic integrated circuit structure and before the step of forming the thermo-optical modulation structure, a first cladding layer is formed on one side of the substrate layer; the first cladding layer covers the side surface of the waveguide core facing away from the substrate layer and the side surface of the waveguide core; After the step of forming the first cladding layer and before the step of forming the piezoelectric modulation structure, a second cladding layer is formed on the side surface of the first cladding layer facing away from the substrate layer, the second cladding layer covering the heating fixed resistor and the thermo-optic electrode; After the step of forming the piezoelectric modulation structure, a third cladding layer is formed on the surface of the second cladding layer facing away from the first cladding layer. The third cladding layer covers the surface and side of the first piezoelectric electrode, the piezoelectric thin film material layer and the second piezoelectric electrode. A first groove, a second groove, and a third groove are formed on the side surface of the third cladding layer facing away from the first cladding layer; the first groove exposes a portion of the surface of the first piezoelectric electrode; the second groove exposes a portion of the surface of the second piezoelectric electrode; the third groove penetrates the third cladding layer and extends into the second cladding layer, exposing the side surface of the thermo-optical electrode facing away from the substrate layer.

12. The method for preparing the piezoelectric-thermo-optic composite modulator according to claim 11, characterized in that, In the step of forming the first groove, the second groove, and the third groove on the side surface of the third cladding layer opposite to the first cladding layer... A first pad is formed on the surface of the first piezoelectric electrode exposed by the first groove, a second pad is formed on the surface of the second piezoelectric electrode exposed by the second groove, and a third pad is formed on the surface of the thermo-optical electrode exposed by the third groove.

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