Optical waveguide device, optical chip, and communication device

Abstract

An optical waveguide device, an optical chip, and a communication device are disclosed, which are related to the field of communication technology. The optical waveguide device includes a substrate, a target structure, and an electro-optic crystal structure. The target structure includes an insulating layer and a first optical waveguide. A bonding region of the insulating layer has a first groove, and the first optical waveguide is embedded in the first groove, and a surface of the first optical waveguide remote from the substrate is flush with a surface of the bonding region remote from the substrate. The electro-optic crystal structure is bonded to a surface of the target structure remote from the substrate. This application can solve the problem that optical waveguide devices have low optical modulation efficiency. This application can be applied to devices that need to convey information based on the phase and / or amplitude of light, such as devices that perform communication based on light or devices that perform switch control based on light.

Description

[Technical Field]

[0001] child The application relates to the field of communications technology, and in particular to optical waveguide devices, optical chips, and communications devices. [Background technology]

[0002] Optical waveguide devices are common devices in the field of communication technology, such as optical modulators, optical switches, or optical phased arrays. Optical waveguide devices usually include an optical waveguide and an electro-optic crystal, and the entire structure formed by the optical waveguide and the electro-optic crystal can perform efficient optical modulation.

[0003] Currently, optical waveguide devices include a substrate, an optical waveguide, an insulating layer, and an electro-optic crystal. The optical waveguide is located on the substrate, and the insulating layer covers the optical waveguide. Furthermore, the surface of the insulating layer farther from the substrate is bonded to the electro-optic crystal.

[0004] However, after the electro-optic crystal and the surface of the insulating layer farther from the substrate are bonded together, a gap exists between the optical waveguide and the electro-optic crystal due to the insulating layer, which affects the optical modulation efficiency of the optical waveguide device. Summary of the Invention

[0005] This application provides an optical waveguide device, an optical chip, and a communication device to solve the problem that the optical waveguide device has low optical modulation efficiency. The technical solutions are as follows:

[0006] According to a first aspect, an optical waveguide device is provided. The optical waveguide device includes a substrate, a target structure, and an electro-optic crystal structure. The target structure includes an insulating layer and a first optical waveguide. A bonding region of the insulating layer has a first groove, and the first optical waveguide is embedded in the first groove, with a surface of the first optical waveguide remote from the substrate being flush with a surface of the bonding region remote from the substrate. The electro-optic crystal structure is bonded to the surface of the target structure remote from the substrate.

[0007] The bonding region may be the entire region of the insulating layer or a portion of the region of the insulating layer. This is not a limitation of the present application. When the bonding region is a portion of the region of the insulating layer, the shape of the other portion of the region of the insulating layer is not a limitation of the present application. The bonding region of the insulating layer is located in a region of the target structure that will be bonded to the electro-optic crystal structure. Therefore, bonding the electro-optic crystal structure to the surface of the target structure that is farther from the substrate can be understood as bonding the electro-optic crystal structure to the region of the surface of the target structure that is farther from the substrate, where the bonding region is located.

[0008] Because the surface of the first optical waveguide far from the substrate is flush with the surface of the junction region of the insulating layer far from the substrate, the surface of the first optical waveguide far from the substrate is not covered by the insulating layer. Therefore, there is no insulating layer between the first optical waveguide and the electro-optic crystal structure, and the distance between the first optical waveguide and the electro-optic crystal structure is small. Furthermore, since the distance between the first optical waveguide and the electro-optic crystal structure is negatively correlated with the optical modulation efficiency of the optical waveguide device, when the distance between the first optical waveguide and the electro-optic crystal structure is small, the overall optical mode field formed by the optical waveguide and the electro-optic crystal is small, and the optical modulation efficiency of the optical waveguide device is high. It should be understood that slight differences caused by small errors in the height between the surface of the first optical waveguide far from the substrate and the surface of the junction region of the insulating layer far from the substrate also fall within the scope of protection of this application.

[0009] Optionally, a first optical waveguide perpendicular to the extension direction of The cross section of the first optical waveguide includes a first side and a second side facing each other, the first side being closer to the substrate and the second side being farther from the substrate, and the length of the first side being equal to or less than the length of the second side. A length of the second side longer than the length of the first side indicates a higher optical modulation efficiency of the optical waveguide device, so when the length of the first side is equal to or less than the length of the second side, the optical modulation efficiency of the optical waveguide device is high.

[0010] The cross section further includes a third side connected to the first side and the second side, and the included angle between the third side and the second side is in the range of [60°, 80°] or [70°, 80°]. For example, the included angle α can be 70°. When the included angle is in the range of [60°, 80°] or [70°, 80°] and the length of the second side is longer than the length of the first side, the optical modulation efficiency of the optical waveguide device is high. When the length of the first side is shorter than the length of the second side, the included angle α between the third side and the second side is equal to 90°.

[0011] The electro-optic crystal structure in this application may have various forms. For example, the electro-optic crystal structure may include a bulk electro-optic crystal or an electro-optic crystal thin film. For example, the electro-optic crystal structure may include lithium niobate thin film, bulk lithium niobate, barium titanate thin film, bulk barium titanate, bulk potassium niobate, and the like. For some electro-optic crystals (e.g., barium titanate), the electro-optic coefficient of the bulk electro-optic crystal is higher than that of the electro-optic crystal thin film. In this case, when a bulk electro-optic crystal is used as the electro-optic crystal structure, the electro-optic coefficient of the electro-optic crystal structure can be high, and the optical modulation efficiency of the optical waveguide device can be high.

[0012] Optionally, when the electro-optic crystal structure includes an electro-optic crystal thin film, the electro-optic crystal structure includes a superimposed support layer and the electro-optic crystal thin film, and the surface of the target structure remote from the substrate is bonded to the side of the electro-optic crystal structure where the electro-optic crystal thin film is located. The support layer is located on the surface of the electro-optic crystal thin film remote from the substrate. Before the electro-optic crystal structure is bonded to the target structure, the electro-optic crystal thin film is placed on the support layer, and the support layer is configured to support the electro-optic crystal thin film. When the electro-optic crystal structure includes an electro-optic crystal thin film, the electro-optic crystal structure may alternatively not include a support layer. This is not a limitation of this application. When the electro-optic crystal structure does not include a support layer or includes a thinner support layer, the overall thickness of the optical waveguide device is small, which facilitates subsequent packaging of the optical waveguide device.

[0013] In addition, the optical waveguide and the electro-optic crystal structure in the optical waveguide device can modulate light under the action of an electric field. Therefore, the optical waveguide device provided in this application may further include an electrode configured to form an electric field. Note that there are various implementations of the electrodes in the optical waveguide device, and two of these implementations are used as examples for explanation below.

[0014] In one optional implementation, the bonding region further has a plurality of second grooves, and the target structure further includes a plurality of electrodes embedded in the plurality of second grooves in one-to-one correspondence, a surface of at least one electrode facing away from the substrate being flush with the surface of the bonding region facing away from the substrate, and a first optical waveguide located between the plurality of electrodes, and the electrodes and first optical waveguides in the optical waveguide device are arranged in a spaced apart one-to-one relationship. For example, the target structure includes two first optical waveguides, the bonding region has three second grooves arranged in sequence, and the target structure includes three electrodes embedded in three grooves in one-to-one correspondence, with one first optical waveguide disposed between every two adjacent electrodes.

[0015] When the surface of the electrode farther from the substrate is flush with the surface of the junction region of the insulating layer farther from the substrate, the surface of the electrode farther from the substrate is not covered by the insulating layer. Therefore, there is no insulating layer between the electrode and the electro-optic crystal structure, and the distance between the electrode and the electro-optic crystal structure is small. Furthermore, since the distance between the electrode and the electro-optic crystal structure is negatively correlated with the optical modulation efficiency of the optical waveguide device, when the distance between the electrode and the electro-optic crystal structure is small, the optical modulation efficiency of the optical waveguide device is high.

[0016] In another optional implementation, the optical waveguide device further includes an electrode located between the substrate and the insulating layer, and the electro-optic crystal structure includes a support layer and an electro-optic crystal thin film superimposed on each other, the support layer including a conductive material, and the surface of the target structure farther from the substrate is bonded to the side of the electro-optic crystal structure where the electro-optic crystal thin film is located. In this case, an electric field can be formed between the electrode and the support layer. Both the first optical waveguide and the electro-optic crystal structure are placed in the electric field, and optical modulation occurs under the action of the electric field.

[0017] In this application, regardless of the implementation of the electrode, the material of the electrode can include at least one of aluminum, tungsten, titanium, titanium nitride, and indium tin oxide. Also, when the material of the electrode is tungsten, if the electrode is also fabricated on a flow plate platform of a complementary metal-oxide-semiconductor (CMOS) process, tungsten residue in the process of fabricating the electrode has little effect on the performance of other devices fabricated on the flow plate platform of the CMOS process, so even if tungsten residue remains on the platform, the tungsten material can be more compatible with the CMOS process.

[0018] The direct contact of the junction region of the insulating layer with the electro-optic crystal structure is used as an example in the above description. Optionally, another film layer may be present between the junction region of the insulating layer and the electro-optic crystal structure. For example, a dielectric layer may be present between the junction region of the insulating layer and the electro-optic crystal structure. The dielectric layer is configured to prevent metal ions on the insulating layer side from diffusing into the electro-optic crystal structure to avoid performance degradation of the electro-optic crystal structure caused by diffusion of metal ions on the insulating layer side into the electro-optic crystal structure.

[0019] Optionally, the thickness of the dielectric layer is 10 nanometers or less. For example, the thickness of the dielectric layer is in the range of 2 nanometers to 10 nanometers. It can be seen that, with a small thickness of the dielectric layer, a small distance between the first optical waveguide and the electro-optical crystal structure, and a small distance between the electrode and the electro-optical crystal structure, the optical modulation efficiency of the entire optical waveguide device is high.

[0020] Optionally, the melting point of the dielectric layer is lower than the melting points of the target structure and the electro-optic crystal structure. Note that the target structure includes multiple portions, and the melting point of the target structure may be the melting point of a portion of the multiple portions that is bonded to the electro-optic crystal structure. The melting point of the electro-optic crystal structure may be the melting point of a portion of the electro-optic crystal structure that is bonded to the target structure. Because the melting point of the dielectric layer is lower than the melting points of the target structure and the electro-optic crystal structure, the target structure, the dielectric layer, and the electro-optic crystal structure can be heated as a whole such that, when the target structure is bonded to the electro-optic crystal structure, the dielectric layer melts but the target structure and the electro-optic crystal structure do not melt. The melted dielectric layer can effectively bond the target structure and the electro-optic crystal structure together, thereby improving the bonding strength between the target structure and the electro-optic crystal structure.

[0021] Additionally, any optical waveguide device provided in this application may further include a second optical waveguide, and the second optical waveguide is coupled to the first optical waveguide. Certainly, the optical waveguide device may not include a second optical waveguide. This is not a limitation of this application. Optionally, the second optical waveguide is located between the substrate and the insulating layer.

[0022] The first and second optical waveguides can be coupled in various ways. In one coupling way, the orthogonal projection of the first optical waveguide onto the substrate and the orthogonal projection of the second optical waveguide onto the substrate at least partially overlap. The orthogonal projection of the end of the first optical waveguide closer to the second optical waveguide onto the substrate is wedge-shaped. The orthogonal projection of the end of the second optical waveguide closer to the first optical waveguide onto the substrate is wedge-shaped.

[0023] Optionally, the modulation efficiency of the optical waveguide device may be expressed by the product (Vπ·Lπ) of the half-wave voltage (Vπ) and the length (Lπ) of the electro-optic crystal structure in the extension direction of the first optical waveguide 022. A smaller product indicates higher modulation efficiency. The optical waveguide device provided in this application has a small Vπ·Lπ, and the modulation efficiency of the optical waveguide device is high.

[0024] For example, the material of the first optical waveguide includes hydrogenated amorphous silicon, the electro-optic crystal structure includes a lithium niobate thin film, and Vπ·Lπ is less than 2.3 volts-cm; or the material of the first optical waveguide includes silicon nitride, the electro-optic crystal structure includes a lithium niobate thin film, and Vπ·Lπ is less than 6.7 volts-cm; or the material of the first optical waveguide includes hydrogenated amorphous silicon, and the electro-optic crystal structure includes barium titanate, and Vπ·Lπ is less than 0.2 volts-cm.

[0025] According to a second aspect, there is provided an optical chip, the optical chip including an optical waveguide device according to any of the designs in the first aspect.

[0026] According to a third aspect, there is provided a communications device, the communications device including the optical chip provided in the second aspect.

[0027] According to a fourth aspect, there is provided a method for manufacturing an optical waveguide device. The method includes forming an insulating layer on a substrate, forming a first groove in a bonding region of the insulating layer, and embedding a first optical waveguide in the first groove. A surface of the first optical waveguide remote from the substrate is flush with a surface of the bonding region remote from the substrate. After obtaining a target structure located on the substrate, the surface of the target structure remote from the substrate is bonded to an electro-optic crystal structure. The target structure includes the insulating layer and the first optical waveguide.

[0028] When an insulating layer and a first optical waveguide are formed on a substrate, an insulating layer may be formed on the substrate first. For example, an insulating material layer may be first formed on the substrate, and then a chemical mechanical polishing (CMP) process may be performed on the insulating material layer to obtain an insulating layer. Then, a first optical waveguide may be formed on the surface of the insulating layer farther from the substrate by using an embedding process, so that the first optical waveguide is embedded in the bonding region of the insulating layer and the surface of the first optical waveguide farther from the substrate is flush with the surface of the bonding region of the insulating layer farther from the substrate. When a first optical waveguide is formed on the surface of the insulating layer farther from the substrate by using an embedding process, a first groove may be first formed in the bonding region of the insulating layer, and then an optical waveguide material layer may be formed on the substrate with the first groove formed thereon. Finally, a CMP process may be performed on the optical waveguide material layer to form the first optical waveguide embedded in the first groove. The material of the optical waveguide material layer can be hydrogenated amorphous silicon (a-Si:H), silicon nitride (SiN), titanium dioxide (TiO2), or the like.

[0029] Since the material of the optical waveguide material layer is different from the material of the insulating layer, when the optical waveguide material layer is subjected to a CMP process, loss in the insulating layer is not significant and the portion of the optical waveguide material layer located outside the first groove can be effectively removed, resulting in a first optical waveguide whose surface remote from the substrate is flush with the surface of the bonding region of the insulating layer remote from the substrate. After the surface of the target structure remote from the substrate and the electro-optic crystal structure are bonded, there is no spacing between the first optical waveguide and the electro-optic crystal structure by the insulating layer.

[0030] Furthermore, in the method for manufacturing an optical waveguide device provided in this application, if the bonding between the target structure and the electro-optic crystal structure is the final manufacturing process of the optical waveguide device, the method can be compatible with CMOS processes.

[0031] Optionally, when the first optical waveguide is embedded in the first groove, a waveguide material layer can be first formed on the insulating layer in which the first groove is formed, and then a CMP process is performed on the surface of the waveguide material layer remote from the substrate to obtain the first optical waveguide embedded in the first groove.

[0032] Optionally, a first optical waveguide perpendicular to the extension direction of The cross section of the first optical waveguide includes a first side and a second side that face each other, the first side being closer to the substrate and the second side being farther from the substrate, and the length of the first side being equal to or less than the length of the second side.

[0033] Optionally, the cross section further includes a third side connected to the first side and the second side, and the included angle between the third side and the second side is in the range of [60°, 80°].

[0034] Optionally, the electro-optic crystal structure comprises a bulk electro-optic crystal or an electro-optic crystal thin film.

[0035] Optionally, the electro-optic crystal structure includes a support layer and an electro-optic crystal thin film superimposed on each other, and when the surface of the target structure remote from the substrate is bonded to the electro-optic crystal structure, the surface of the target structure remote from the substrate can be bonded to the side of the electro-optic crystal structure where the electro-optic crystal thin film is located. After the surface of the target structure remote from the substrate is bonded to the electro-optic crystal structure, the support layer can be further thinned or removed. Because the support layer is thinned or removed, the overall thickness of the optical waveguide device finally obtained is small, which facilitates subsequent packaging of the optical waveguide device.

[0036] Optionally, the method further comprises forming a plurality of second grooves in the bonding region and embedding a plurality of electrodes in the plurality of second grooves in a one-to-one correspondence, wherein a surface of at least one electrode facing away from the substrate is flush with a surface of the bonding region facing away from the substrate, the target structure further comprising the plurality of electrodes, a first optical waveguide being located between the plurality of electrodes, and the electrodes and the first optical waveguide in the optical waveguide device being arranged in a spaced apart relationship in a one-to-one relationship.

[0037] For example, when multiple electrodes are embedded in the multiple second grooves in a one-to-one correspondence, a conductive material layer can be first formed on the insulating layer in which the multiple second grooves are formed, and then a CMP process is performed on the surface of the conductive material layer remote from the substrate to obtain the multiple electrodes embedded in the multiple second grooves in a one-to-one correspondence. Because the material of the conductive material layer is different from the material of the insulating layer, when the CMP process is performed on the conductive material layer, loss of the insulating layer is not significant and the portions of the conductive material layer located outside the second grooves can be effectively removed, resulting in an electrode whose surface remote from the substrate is flush with the surface of the junction region of the insulating layer remote from the substrate.

[0038] Optionally, forming a plurality of second grooves in the junction region includes forming a plurality of second grooves in the insulating layer in which the first optical waveguide is embedded. In this application, a case in which the first optical waveguide is formed first and then the electrode is formed is used as an example. It is certainly possible to form the electrode first and then the first optical waveguide.

[0039] Optionally, an electrode may be further formed on the substrate before the insulating layer is formed on the substrate, and when the insulating layer is formed on the substrate, the insulating layer can be formed on the substrate on which the electrode is formed.

[0040] The electro-optic crystal structure includes a support layer and an electro-optic crystal thin film superimposed on each other, the support layer including a conductive material, and when the surface of the target structure farther from the substrate is bonded to the electro-optic crystal structure, the surface of the target structure farther from the substrate can be bonded to the side of the electro-optic crystal structure where the electro-optic crystal thin film is located.

[0041] Optionally, the material of the electrode includes at least one of aluminum, tungsten, titanium, titanium nitride, and indium tin oxide.

[0042] Optionally, before the surface of the target structure remote from the substrate is bonded to the electro-optic crystal structure, a dielectric layer may be formed on the insulating layer in which the first optical waveguide is embedded, the target structure further comprising the dielectric layer configured to prevent metal ions in the electrode from diffusing into the electro-optic crystal structure.

[0043] Optionally, when a dielectric layer is formed on the insulating layer in which the first optical waveguide is embedded, the dielectric layer can be deposited on the insulating layer in which the first optical waveguide is embedded.

[0044] Optionally, the dielectric layer has a thickness of 10 nanometers or less.

[0045] Optionally, the melting point of the dielectric layer is lower than the melting point of the target structure and the melting point of the electro-optic crystal structure. The target structure, the dielectric layer, and the electro-optic crystal structure can be heated such that when the target structure is bonded to the electro-optic crystal structure, the dielectric layer melts but the target structure and the electro-optic crystal structure do not melt.

[0046] Optionally, a second optical waveguide may be further formed on the substrate before the insulating layer is formed on the substrate, and the first optical waveguide is coupled to the second optical waveguide. When the insulating layer is formed on the substrate, the insulating layer can be formed on the substrate on which the second optical waveguide is formed.

[0047] Optionally, an orthogonal projection of the first light guide onto the substrate and an orthogonal projection of the second light guide onto the substrate at least partially overlap. An orthogonal projection of an end of the first light guide closer to the second light guide onto the substrate is wedge-shaped. An orthogonal projection of an end of the second light guide closer to the first light guide onto the substrate is wedge-shaped.

[0048] Optionally, when an insulating layer is formed on a substrate, an insulating material layer can be formed on the substrate first, and then a CMP process is performed on the surface of the insulating material layer remote from the substrate to obtain the insulating layer.

[0049] For the technical effects provided by any of the designs in the second to fourth aspects, please refer to the technical effects provided by the corresponding design in the first aspect, and the details will not be described again here. [Brief explanation of the drawings]

[0050] [Figure 1] 1 is a schematic diagram of the configuration of a communication device according to an embodiment of the present application; [Figure 2] 1 is a schematic diagram of an optical chip configuration according to one embodiment of the present application; [Figure 3] FIG. 1 is a schematic diagram of another configuration of an optical chip according to an embodiment of the present application. [Figure 4] FIG. 1 is a schematic diagram of another configuration of an optical chip according to an embodiment of the present application. [Figure 5] 1 is a schematic diagram of a configuration of an optical waveguide device according to an embodiment of the present application; [Figure 6] FIG. 2 is a schematic diagram of another structure of an optical waveguide device according to an embodiment of the present application. [Figure 7] FIG. 2 is a schematic diagram of another structure of an optical waveguide device according to an embodiment of the present application. [Figure 8] 2 is a schematic diagram of a cross section of a first optical waveguide according to an embodiment of the present application; [Figure 9]FIG. 2 is a schematic diagram of another structure of an optical waveguide device according to an embodiment of the present application. [Figure 10] 1 is a schematic diagram of an electrode implementation according to an embodiment of the present application. [Figure 11] FIG. 10 is a schematic diagram of another implementation of an electrode according to an embodiment of the present application. [Figure 12] FIG. 1 is a top view of an optical waveguide device according to an embodiment of the present application. [Figure 13] FIG. 2 is a schematic diagram of another structure of an optical waveguide device according to an embodiment of the present application. [Figure 14] FIG. 2 is another top view of an optical waveguide device according to an embodiment of the present application. [Figure 15] 1 is a schematic diagram of a cross section of an optical waveguide device according to an embodiment of the present application; [Figure 16] FIG. 2 is another schematic diagram of a cross section of an optical waveguide device according to an embodiment of the present application. [Figure 17] 1 is a schematic diagram of a projection scheme according to an embodiment of the present application; [Figure 18] FIG. 2 is a schematic diagram of an orthogonal projection of a first optical waveguide and a second optical waveguide on a substrate according to an embodiment of the present application. [Figure 19] FIG. 2 is another top view of an optical waveguide device according to an embodiment of the present application. [Figure 20] FIG. 2 is another schematic diagram of a cross section of an optical waveguide device according to an embodiment of the present application. [Figure 21] FIG. 2 is another schematic diagram of a cross section of an optical waveguide device according to an embodiment of the present application. [Figure 22] 1 is a flowchart of a method for manufacturing an optical waveguide device according to an embodiment of the present application. [Figure 23] 1 is a schematic diagram of a manufacturing process for an optical waveguide device according to an embodiment of the present application. [Figure 24] 3A-3C are schematic diagrams of another manufacturing process for an optical waveguide device according to an embodiment of the present application. [Figure 25] 3A-3C are schematic diagrams of another manufacturing process for an optical waveguide device according to an embodiment of the present application. [Figure 26] 3A-3C are schematic diagrams of another manufacturing process for an optical waveguide device according to an embodiment of the present application. [Figure 27] 3A-3C are schematic diagrams of another manufacturing process for an optical waveguide device according to an embodiment of the present application. [Figure 28] 3A-3C are schematic diagrams of another manufacturing process for an optical waveguide device according to an embodiment of the present application. [Figure 29] 3A-3C are schematic diagrams of another manufacturing process for an optical waveguide device according to an embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0051] In order to make the principles and technical solutions of this application clearer, the following further describes the implementation of this application in detail with reference to the accompanying drawings.

[0052] A communication device typically communicates using light, but the communication device may be any device that uses light for communication, such as a router, gateway, base station, or server.

[0053] The communication device includes an optical chip, such as a photonic integrated circuit (PIC) or an electronic-photonic integrated circuit (EPIC), that can load an electrical signal onto the light by modulating the phase or intensity of the light.

[0054] In addition to the optical chip, the communication device may further include other components, such as a processor and a memory. The processor is coupled to the memory and configured to read instructions in the memory and then execute the method described in the embodiments of this application, which is executed by the communication device, according to the instructions. In the communication device, there may be multiple processors, and the memory coupled to the processor may be independent of the processor or the communication device, or may be integrated into the processor or the communication device. communicationThe memory may be located inside the device. The memory may be a physically independent unit, or may be a storage space on a cloud server, a web disk, etc. Optionally, there may be one or more memories. When there are multiple memories, the multiple memories may be located in the same location or in different locations, and may be used independently or in cooperation. For example, when the memory is located inside the communication device, please refer to FIG. 1. FIG. 1 is a schematic diagram of the configuration of a communication device according to one embodiment of this application. The communication device includes an optical chip 200, a processor 202, and a memory 201. The memory 201 is configured to store a program, and the processor 202 is configured to call the program stored in the memory 201, so that the communication device performs a corresponding method or function. Optionally, FIG. 1 As shown in FIG. 1, the communication device may further include at least one communication interface 203 and at least one communication bus 204. The memory 201, the processor 202, and the communication interface 203 are connected via the communication bus 204. The communication interface 203 is configured to communicate with another device under the control of the processor 202, and the processor 202 can call a program stored in the memory 201 via the communication bus 204. The communication interface 203 may include an optical chip 200.

[0055] The optical chip in the communication device may include an optical waveguide device configured to modulate the phase and / or intensity of light, and optionally, the optical waveguide device may further include other components in addition to the optical waveguide device.

[0056] For example, as shown in Figure 2, the optical chip includes a laser unit and a modulator. The modulator is an optical waveguide device, such as a Mach-Zehnder Interferometer (MZI) modulator. The laser unit is configured to emit a laser, and the modulator is configured to modulate the phase or intensity of the laser emitted by the laser unit.

[0057] In another example, as shown in Figure 3, based on Figure 2, the optical chip further includes a CMOS circuit and a detector. The modulator modulates the laser emitted by the laser unit into an optical signal, and then outputs the optical signal to the optical chip. The detector is configured to convert the optical signal received by the optical chip into an electrical signal. CMOS The circuitry is connected to the laser unit, the modulator, and the detector. CMOS The circuit is configured to control the laser unit to emit light, send an electrical signal to the modulator so that the modulator modulates the laser emitted by the laser unit based on the electrical signal, and process the resulting electrical signal through conversion by the detector. Optionally, the optical chip may further include another detector (not shown in FIG. 3). The detector is also connected to the CMOS circuit. The detector is configured to convert the optical signal modulated by the modulator into an electrical signal. CMOS The circuitry may be configured to detect the effect of modulating the laser by the modulator based on the electrical signal.

[0058] In yet another example, as shown in Figure 4, the optical chip includes an optical waveguide device and a passive device. The passive device may be a coupler, an optical splitter, an optical combiner, or the like. In Figure 4, the passive device is an optical splitter as an example. In Figure 4, the optical splitter is configured to split the modulated laser light output by the optical waveguide device into three modulated laser light beams.

[0059] From the above, it can be seen that an optical waveguide device is one of the important devices in an optical chip, and the optical waveguide device can be any device that includes an optical waveguide, such as an optical modulator, an optical switch, or an optical phased array. The optical waveguide device modulates light using the optical waveguide in the optical waveguide device. Currently, the optical waveguide in the optical waveguide device can be a silicon optical waveguide. The silicon optical waveguide modulates light using the carrier dispersion effect of silicon. The carrier dispersion effect is a phenomenon in which a change in the injected carriers causes a change in the refractive index of a material (e.g., a silicon optical waveguide).

[0060] Optical chips typically feature high modulation bandwidth, low modulation voltage, small insertion loss, good linearity, low power consumption, and easy integration. However, silicon optical waveguides modulate light by utilizing the carrier dispersion effect of silicon. The carrier dispersion effect not only changes the refractive index of silicon optical waveguides, but also changes the optical absorption coefficient of silicon optical waveguides. As a result, optical waveguide devices have problems such as high insertion loss, low extinction, and difficulty in further improving modulation bandwidth. As a result, the performance of optical waveguide devices and optical chips incorporating optical waveguide devices is insufficient.

[0061] To improve the performance of optical waveguide devices and optical chips, electro-optical materials with larger electro-optical coefficients (also called Pockels coefficients) (larger than that of optical waveguides), such as lithium niobate (LiNbO3, LN) crystals, barium titanate (BaTiO3, BTO) crystals, potassium niobate (KNbO3, KBO) crystals, organic electro-optical materials, and the like, can be mixed into optical waveguide devices.

[0062] For example, Fig. 5 is a schematic diagram of the structure of an optical waveguide device according to one embodiment of the present application. As shown in Fig. 5, the optical waveguide device includes a substrate 21, an optical waveguide 22, an insulating layer 23, and an electro-optic crystal 24. The optical waveguide 22 is located on the substrate 21, the insulating layer 23 covers the optical waveguide 22, and the surface of the insulating layer 23 farther from the substrate is bonded to the electro-optic crystal 24.

[0063] When manufacturing the optical waveguide device shown in Figure 5, typically, first an optical waveguide 22 is formed on a substrate 21, then an insulating material layer covering the optical waveguide 22 is formed on the substrate 21 on which the optical waveguide 22 is formed, and an insulating layer 23 is obtained by performing a CMP process on the insulating material layer, and finally an electro-optic crystal 24 is bonded to the surface of the insulating layer 23 that is farther from the substrate 21.

[0064] The purpose of the CMP process is to remove the portion of the insulating material layer that extends beyond the optical waveguide. However, when the CMP process is performed on the insulating material layer, significant loss occurs in the portion of the insulating material layer that does not extend beyond the optical waveguide, which can easily cause the optical waveguide 22 to protrude from the insulating layer 23. Therefore, to prevent the optical waveguide 22 from protruding from the insulating layer 23, it is necessary to secure the portion of the insulating material layer that extends beyond the optical waveguide 22 when the CMP process is performed on the insulating material layer. Thus, the insulating layer 23 obtained through the CMP process covers the optical waveguide 22. After the surface of the insulating layer 23 farthest from the substrate is bonded to the electro-optic crystal 24, the insulating layer 23 provides a gap between the optical waveguide 22 and the electro-optic crystal 24.

[0065] The distance between the optical waveguide 22 and the electro-optic crystal 24 has a negative relationship with the optical modulation efficiency of the optical waveguide device. When there is a gap between the optical waveguide 22 and the electro-optic crystal 24, the distance between the optical waveguide 22 and the electro-optic crystal 24 cannot be too small (for example, the distance is 1.148 micrometers or 30 nanometers). As a result, the entire optical mode field formed by the optical waveguide and the electro-optic crystal is large, and the optical modulation efficiency of the optical waveguide device is low.

[0066] 5, the optical waveguide device further includes an electrode 25, which is placed on the surface of the electro-optic crystal 24 remote from the substrate 21. The entire structure formed by the optical waveguide 22 and the electro-optic crystal 24 is configured to modulate light under the action of an electric field generated by the electrode 25. In this case, in the process of manufacturing the optical waveguide device, the electrode 25 can be formed on the surface of the electro-optic crystal 24 remote from the substrate 21 after the surface of the insulating layer 23 remote from the substrate 21 is bonded to the electro-optic crystal 24.

[0067] However, because the bonding process does not belong to the CMOS process, the entire process of fabricating an optical waveguide device cannot be completed completely on a flow plate platform of a CMOS process. When an optical waveguide device is fabricated by combining a CMOS process and a bonding process, an optical waveguide 22 and an insulating layer 23 are first formed on a substrate on a flow plate platform of a CMOS process. Then, the substrate 21 on which the insulating layer 23 is formed is removed from the flow plate platform of the CMOS process, and the insulating layer 23 and the electro-optic crystal 24 are bonded using a bonding process. However, after the insulating layer 23 and the electro-optic crystal 24 are bonded, the insulating layer 23 is now removed from the flow plate platform of the CMOS process, so the electrode 25 cannot be formed on the flow plate platform. It is clear that the optical waveguide device shown in FIG. 5 cannot be fabricated by combining a CMOS process and a bonding process, and the manufacturing method of this optical waveguide device is not compatible with the CMOS process.

[0068] The position of the electrode 25 in the optical waveguide device may also be different from that shown in FIG. 5. As shown in FIG. 6, the electrode 25 may be placed between the optical waveguide 22 and the substrate 21. In this case, the optical waveguide device further includes another insulating layer 26 located between the electrode 25 and the optical waveguide 22. Similar to the above-described positional relationship between the insulating layer 23 and the optical waveguide 22, the another insulating layer 26 also covers the electrode 25. In this case, in the process of manufacturing the optical waveguide device, before the optical waveguide 22 is formed on the substrate 21, the electrode 25 and the insulating layer 26 need to be formed in sequence on the substrate 21, and then the optical waveguide 22 needs to be formed on the insulating layer 26.

[0069] The distance between the electrode 25 and the electro-optic crystal 24 has a negative relationship with the optical modulation efficiency of the optical waveguide device. 23 , an optical waveguide 22, and an insulating layer 26 , a distance is provided between the electrode 25 and the electro-optic crystal 24. It can be seen that the distance between the electrode 25 and the electro-optic crystal 24 cannot be made too small. As a result, the electric field of the electrode 25 applied to the electro-optic crystal 24 is low, and the optical modulation efficiency of the optical waveguide device is low.

[0070] In some cases, the material of electrode 25 is gold. If electrode 25 is also fabricated on a flow plate platform in a CMOS process, the process of fabricating electrode 25 is likely to leave gold residue on the flow plate platform. The gold residue has a significant impact on the performance of other devices fabricated on the flow plate platform in a CMOS process, making the material gold difficult to be compatible with the CMOS process.

[0071] In some of the optical waveguide devices described above (the optical waveguide devices shown in FIG. 5 or FIG. 6), the optical waveguide 22 is formed by dry etching. As a result, the optical waveguide 22 has a cross section perpendicular to the extending direction of the optical waveguide 22, which is Positive The cross section is trapezoidal, and the length of the first side closer to the substrate (farther from the electro-optic crystal) in the cross section is close ) is longer than the length of the second side of one of the optical waveguide devices. The cross section shown in FIG. 5 or FIG. 6 is a regular trapezoid. However, it has been found through experiments that a longer second side than a longer first side indicates higher optical modulation efficiency of the optical waveguide device. In some of the optical waveguide devices mentioned above, the length of the second side is shorter than the length of the first side, so the optical modulation efficiency of these optical waveguide devices is low.

[0072] Furthermore, when the electro-optic crystal in the above-mentioned optical waveguide device is a barium titanate thin film formed on a support layer, the electro-optic coefficient of the barium titanate thin film, 1000 picometers per volt (pm / V), is small (smaller than the electro-optic coefficient of bulk barium titanate, 1920 pm / V), so the overall optical modulation efficiency formed by the optical waveguide and the electro-optic crystal is low, and the optical modulation efficiency of the optical waveguide device is low.

[0073] In light of the above-mentioned problems, embodiments of this application provide an optical waveguide device and a manufacturing method thereof. In the optical waveguide device, the surface of the optical waveguide farther from the substrate is flush with the surface of the insulating layer farther from the substrate (i.e., the insulating layer does not cover the optical waveguide), the surface of the electrode farther from the substrate is also flush with the surface of the insulating layer farther from the substrate (i.e., the insulating layer does not cover the electrode), and the length of the second side of the cross section of the optical waveguide can be equal to or greater than the length of the first side. Furthermore, if the electro-optic coefficient of the bulk electro-optic crystal of the material is greater than that of the electro-optic crystal thin film of the material, the electro-optic crystal structure in the optical waveguide device can include a bulk electro-optic crystal having a higher electro-optic coefficient. Thus, the optical modulation efficiency of the optical waveguide device is high. Furthermore, in the manufacturing method of the optical waveguide device, the electro-optic crystal structure is bonded last, and the material of the electrode in the optical waveguide device can be tungsten, which has little impact on the performance of other devices. Therefore, the manufacturing method of the optical waveguide device is also compatible with CMOS processes.

[0074] For example, Figure 7 is a schematic diagram of another structure of an optical waveguide device according to an embodiment of the present application. As shown in Figure 7, the optical waveguide device includes a substrate 01, a target structure 02, and an electro-optic crystal structure 03. The target structure 02 includes an insulating layer 021 and a first optical waveguide 022.

[0075] The junction region of the insulating layer 021 has a first groove 101 (also referred to as a first via hole). Note that FIG. 7 shows only the junction region of the insulating layer 021. The junction region may be the entire region of the insulating layer 021, or may be a part of the region of the insulating layer 021. This is not limited in this embodiment of the present application. When the junction region is a part of the region of the insulating layer 021, the shape of the other part of the region of the insulating layer 021 is not limited in this embodiment of the present application.

[0076] The first optical waveguide 022 in the target structure 02 is embedded in the first groove 101 in the bonding region of the insulating layer 021, with the surface of the first optical waveguide 022 remote from the substrate 01 being flush with the surface of the bonding region of the insulating layer 021 remote from the substrate 01. As can be seen, the insulating layer 021 does not cover the face of the first optical waveguide 022 remote from the substrate.

[0077] The electro-optic crystal structure 03 is bonded to the surface of the target structure 02 that is farther from the substrate 01. The bonding area of ​​the insulating layer 021 is in contact with the electro-optic crystal structure 03 in the target structure 02. 03 The electro-optical crystal structure 03 is located in a region where the bonding region is located on the surface of the target structure 02 remote from the substrate 01. Therefore, bonding the electro-optical crystal structure 03 to the surface of the target structure 02 remote from the substrate 01 can be understood as bonding the electro-optical crystal structure 03 to the region where the bonding region is located on the surface of the target structure 02 remote from the substrate 01. The material of the electro-optical crystal structure 03 can be any electro-optical crystal, for example lithium niobate, barium titanate, or potassium niobate.

[0078] The number of first optical waveguides 022 is not limited in this embodiment of the present application. In Fig. 7, the target structure 02 includes two first optical waveguides 022 as an example. Optionally, the target structure 02 may instead include one first optical waveguide 022, or three first optical waveguides 022, etc. The number of first grooves 101 may be equal to the number of first optical waveguides 022, with one first optical waveguide 022 embedded in each first groove 101.

[0079] Because the surface of the first optical waveguide 022 farther from the substrate 01 is flush with the surface of the junction region of the insulating layer 021 farther from the substrate 01, the surface of the first optical waveguide 022 farther from the substrate 01 is not covered by the insulating layer 021. Therefore, there is no insulating layer 021 between the first optical waveguide 022 and the electro-optic crystal structure 03, and the distance between the first optical waveguide 022 and the electro-optic crystal structure 03 is short. Furthermore, since the distance between the first optical waveguide 022 and the electro-optic crystal structure 03 is negatively correlated with the optical modulation efficiency of the optical waveguide device, when the distance between the first optical waveguide 022 and the electro-optic crystal structure 03 is short, the entire optical mode field formed by the optical waveguide and the electro-optic crystal is small, and the optical modulation efficiency of the optical waveguide device is high.

[0080] When the insulating layer 021 and the first optical waveguide 022 are formed on the substrate 01, the insulating layer 021 can be formed first on the substrate 01. For example, an insulating material layer can be formed on the substrate 01 first, and then the insulating material layer can be subjected to a CMP process to form the insulating layer 021. 021Then, the first optical waveguide 022 can be formed on the side of the insulating layer 021 farther from the substrate 01 by using an embedding process, so that the first optical waveguide 022 is embedded in the junction region of the insulating layer 021 and the surface of the first optical waveguide 022 farther from the substrate 01 is flush with the surface of the insulating layer 021 farther from the substrate 01. When the first optical waveguide 022 is formed on the side of the insulating layer 021 farther from the substrate 01 by using the embedding process, a first groove 101 can be first formed in the junction region of the insulating layer 021, then an optical waveguide material layer is formed on the substrate 01 with the first groove 101 formed therein, and finally a CMP process is performed on the optical waveguide material layer to form the first optical waveguide 022 embedded in the first groove 101. The material of the optical waveguide material layer can be a-Si:H, SiN, TiO2, or the like.

[0081] Because the material of the optical waveguide material layer is different from the material of the insulating layer 021, when the optical waveguide material layer is subjected to a CMP process, the loss in the insulating layer 021 is not significant, and the portion of the optical waveguide material layer located outside the first groove 101 can be effectively removed, resulting in a first optical waveguide 022 whose surface remote from the substrate 01 is flush with the surface of the bonding region of the insulating layer 021 remote from the substrate 01. After the surface of the target structure remote from the substrate 01 and the electro-optic crystal structure 03 are bonded, no spacing is provided between the first optical waveguide 022 and the electro-optic crystal structure 03 by the insulating layer 021.

[0082] It should be noted that the optical waveguide device provided in this embodiment of the present application may further include a structure other than the structure shown in FIG. 7 . This is not limited to this embodiment of the present application. For example, a circuit layer or the like may further exist between the substrate 01 and the insulating layer 021 in FIG. 7 . Before portions of the optical waveguide device other than the substrate 01 are fabricated, other structures may be formed on the substrate 01 using a precursor process of the CMOS process. Furthermore, the substrate 01 here may be any substrate, such as a silicon substrate or a silicon nitride substrate.

[0083] In addition, the first optical waveguide 022 perpendicular to the extension direction of The cross section of the first optical waveguide 022 can be seen in Figure 8. The cross section includes a first side A and a second side B that are opposite to each other. The first side A is closer to the substrate 01, and the second side B is closer to the substrate 02. 01 The side farthest from the first side is the second side B, and the length L1 of the first side A is equal to or less than the length L2 of the second side B. In FIG. 8, the length L1 of the first side A is shorter than the length L2 of the second side B as an example (the cross section in FIG. 8 is an inverted trapezoid). Optionally, the length L1 of the first side A may be equal to the length L2 of the second side B (in this case, the cross section is rectangular). Since a length of the second side B longer than the length of the first side A indicates a higher optical modulation efficiency of the optical waveguide device, when the length L1 of the first side A is equal to or less than the length L2 of the second side B, the optical modulation efficiency of the optical waveguide device is high.

[0084] In order to make the length of the first side A equal to or less than the length of the second side B, the first groove 101 that needs to be formed on the insulating layer 021 can be designed as follows: the first groove 101 is located on a cross section in the extension direction of the first groove 101 (parallel to the extension direction of the first optical waveguide 022), and the length of the side on which the bottom surface of the first groove 101 is located is equal to or less than the length of the side on which the opening surface of the first groove 101 is located. In this way, after the first optical waveguide 022 is formed on the substrate on which the first groove 101 is formed, a first optical waveguide 022 whose length of the first side A is equal to or less than the length of the second side B can be obtained.

[0085] Continuing to refer to FIG. 8. First optical waveguide 022 perpendicular to the extension direction of The cross section of the first optical waveguide 022 further includes a third side C connected to the first side A and the second side B. When the length L1 of the first side A is shorter than the length L2 of the second side B, the included angle α between the third side C and the second side B may be in the range of [60°, 80°] or [70°, 80°]. For example, the included angle α may be 70 degrees. When the length L1 of the first side A is shorter than the length L2 of the second side B, If it is equal toThe included angle α between the third side C and the second side B is equal to 90°. When the included angle α is in the range of [60°, 80°] or [70°, 80°] and the length of the second side B is longer than the length of the first side A, the optical modulation efficiency of the optical waveguide device is high.

[0086] The electro-optic crystal structure 03 in this embodiment of the present application may have various forms. For example, the electro-optic crystal structure 03 may include a bulk electro-optic crystal or an electro-optic crystal thin film. For example, the electro-optic crystal structure 03 may include a lithium niobate thin film, bulk lithium niobate, barium titanate thin film, bulk barium titanate, bulk potassium niobate, and the like. For some electro-optic crystals (e.g., barium titanate), the electro-optic coefficient of the bulk electro-optic crystal is higher than that of the electro-optic crystal thin film. In this case, when a bulk electro-optic crystal is used as the electro-optic crystal structure 03, the electro-optic coefficient of the electro-optic crystal structure may be high, and the optical modulation efficiency of the optical waveguide device may be high.

[0087] Optionally, when the electro-optic crystal structure 03 includes an electro-optic crystal thin film, as shown in Figure 9, based on the optical waveguide device shown in Figure 7, the electro-optic crystal structure 03 includes a superimposed support layer 031 and an electro-optic crystal thin film 032, and the surface of the target structure 02 remote from the substrate 01 is bonded to the side of the electro-optic crystal structure 03 where the electro-optic crystal thin film 032 is located. The support layer 031 is located on the surface of the electro-optic crystal thin film 032 remote from the substrate 01. Before the electro-optic crystal structure 03 is bonded to the target structure 02, the electro-optic crystal thin film 032 is disposed on the support layer 031, and the support layer 031 is configured to support the electro-optic crystal thin film 032.

[0088] The support layer 031 may have a single layer structure or a multi-layer structure. This is not limited to this embodiment of the present application. For example, 031 When the structure is multi-layered, the support layer 031may include a superimposed silicon substrate and silicon dioxide layer, with the electro-optic crystal thin film 032 superimposed on the side of the silicon dioxide layer remote from the silicon substrate.

[0089] It should be further noted that when the electro-optic crystal structure 03 includes an electro-optic crystal thin film, the electro-optic crystal structure 03 may also include only the electro-optic crystal thin film 032 without including the support layer 031. In this case, after the electro-optic crystal thin film 032 side of the electro-optic crystal structure 03 is bonded to the target structure 02, the support layer 031 in the electro-optic crystal structure 03 may further be removed. Alternatively, the electro-optic crystal structure 03 may also include the electro-optic crystal thin film 032 and the support layer 031, and the thickness of the support layer 031 is smaller than the thickness of the support layer used to support the electro-optic crystal thin film 032 before bonding. In this case, after the electro-optic crystal thin film 032 side of the electro-optic crystal structure 03 is bonded to the target structure 02, the support layer originally used to support the electro-optic crystal thin film 032 can be thinned to obtain the support layer 031.

[0090] If the electro-optical crystal structure 03 does not include the support layer 031 or includes a thinner support layer 031, the thickness of the entire optical waveguide device is small, which facilitates the subsequent packaging of the optical waveguide device.

[0091] Furthermore, the optical waveguide 022 and the electro-optical crystal structure 03 in the optical waveguide device can modulate light under the action of an electric field. Therefore, the optical waveguide device provided in this embodiment of the present application can further include electrodes configured to form an electric field. Note that there are various implementations of the electrodes in the optical waveguide device, and two of these implementations are used as examples for explanation below.

[0092] (1) One implementation of the electrode can be shown in Fig. 10. Please refer to Fig. 10. Based on Fig. 7, the bonding region further has a plurality of second grooves 102 (also referred to as second vias), the target structure 02 further includes a plurality of electrodes 023 embedded in the plurality of second grooves 102 in a one-to-one correspondence, the first optical waveguide 022 is located between the plurality of electrodes 023, and the electrodes 023 and the first optical waveguide 022 in the optical waveguide device are arranged in a one-to-one relationship with a gap therebetween.

[0093] For example, the target structure 02 includes two first optical waveguides 022, and the junction region has three second grooves 102 arranged in sequence. The target structure 02 includes three electrodes 023 embedded in the three grooves 102 in a one-to-one correspondence. A first optical waveguide 022 is disposed between every two adjacent electrodes 023. The central electrode 023 of the three electrodes 023 can receive an electrical signal, and the two electrodes 023 on both sides can be grounded. Thus, an electric field is formed between every two adjacent electrodes. The electro-optic crystal structure 03 and the first optical waveguides 022 disposed between every two electrodes can modulate light under the action of the electric field. The central grounded electrode 023 may be represented as S, and the two electrodes 023 on both sides may be represented as G. Therefore, the three electrodes 023 shown in FIG. 10 form a GSG electrode structure.

[0094] It should be noted that this embodiment of the present application uses as an example a target structure 02 that includes three electrodes 023. Alternatively, the number of electrodes 023 in the target structure 02 does not have to be three. For example, the target structure 02 includes two electrodes 023. In this case, the target structure 02 may include one first optical waveguide 022 located between the two electrodes 023.

[0095] Optionally, in the plurality of electrodes 023, the surface of at least one electrode 023 that is remote from the substrate 01 is flush with the surface of the bonding region of the insulating layer 021 that is remote from the substrate 01. In Figure 10, an example is used in which the surface of the plurality of electrodes 023 that is remote from the substrate 01 is flush with the surface of the bonding region of the insulating layer 021 that is remote from the substrate 01.

[0096] When the surface of the electrode 023 farther from the substrate 01 is flush with the surface of the junction region of the insulating layer 021 farther from the substrate 01, the surface of the electrode 023 farther from the substrate 01 is not covered by the insulating layer 021. Therefore, there is no insulating layer 021 between the electrode 023 and the electro-optic crystal structure 03, and the distance between the electrode 023 and the electro-optic crystal structure 03 is short. Furthermore, since the distance between the electrode 023 and the electro-optic crystal structure 03 is negatively correlated with the optical modulation efficiency of the optical waveguide device, when the distance between the electrode 023 and the electro-optic crystal structure 03 is short, the optical modulation efficiency of the optical waveguide device is high.

[0097] (2) Another possible implementation of the electrode can be shown in FIG. 11. FIG. 11 is a schematic diagram of the ZZ cross section of FIG. 12. FIG. 12 does not show the substrate 01, the connection portion 103, and the insulating layer 021 in FIG. 11. Please refer to FIG. 11. Based on FIG. 7, the optical waveguide device further includes an electrode 023 located between the substrate 01 and the insulating layer 021. In this case, the electro-optical crystal structure 03 includes a support layer 031 and an electro-optical crystal thin film 032 superimposed on each other, and the support layer 031 includes a conductive material. The surface of the target structure 02 remote from the substrate 01 is bonded to the side of the electro-optical crystal structure 03 where the electro-optical crystal thin film 032 is located.

[0098] 11, an electric field can be formed between the electrode 023 and the support layer 031. Both the first optical waveguide 022 and the electro-optic crystal structure 03 are placed in the electric field, and optical modulation occurs under the action of the electric field.

[0099] For example, see Figure 11. The optical waveguide device further includes a connection portion 103 located on the surface of the insulating layer 021 remote from the substrate 01. The connection portion 103 is electrically conductive and is connected to an electrode 023 through a via in the insulating layer 021. Electrode 023 When an electrical signal is applied to the electrode 101, the electrical signal is transmitted to the electrode 101 via the connection 103. 023 can be given to.

[0100] The support layer 031 may have a single-layer structure or a multi-layer structure. When the support layer 031 contains a conductive material, if the support layer 031 has a single-layer structure, all materials in the single-layer structure may be conductive materials. If the support layer 031 has a multi-layer structure, all materials in the multi-layer structure may be conductive materials. Alternatively, one or more layers in the multi-layer structure that are distant from the electro-optic crystal thin film 032 may contain conductive materials, and the other layers may contain insulating materials. The conductive material in the support layer 031 may be metal, highly doped silicon, or the like.

[0101] In this embodiment of the application, regardless of the implementation of the electrode 023, the material of the electrode 023 may include at least one of aluminum, tungsten, titanium, titanium nitride, and indium tin oxide. Also, when the material of the electrode 023 is tungsten, if the electrode 023 is also fabricated on a flow plate platform of a CMOS process, even if tungsten residue remains on the platform, the material tungsten can be more compatible with the CMOS process, since in the process of fabricating the electrode, tungsten residue has little effect on the performance of other devices fabricated on the flow plate platform of the CMOS process.

[0102] The direct contact of the junction region of the insulating layer 021 with the electro-optic crystal structure 03 is used as an example in the above embodiment. Optionally, there may be another film layer between the junction region of the insulating layer 021 and the electro-optic crystal structure 03. For example, 03 A dielectric layer may be present between the insulating layer 021 and the electro-optical crystal structure 03. The dielectric layer is configured to prevent metal ions on the insulating layer 021 side from diffusing into the electro-optical crystal structure 03, in order to avoid performance degradation of the electro-optical crystal structure caused by diffusion of metal ions on the insulating layer 021 side into the electro-optical crystal structure 03. When the material of the electrode 023 includes a metal material, the metal ions may be metal ions in the electrode 023. The material of the dielectric layer may be aluminum oxide (Al2O3), aluminum nitride (AlN), BCB (benzocyclobutene), or the like.

[0103] 13, based on the optical waveguide device shown in FIG. 10, the target structure 02 further includes a dielectric layer 024 located between the junction region of the insulating layer 021 and the electro-optic crystal structure 03. The dielectric layer 024 is configured to prevent metal ions in the electrode 023 from diffusing into the electro-optic crystal structure 03, in order to avoid performance degradation of the electro-optic crystal structure 03 caused by the diffusion of metal ions in the electrode 023 into the electro-optic crystal structure 03.

[0104] It should be noted that the thickness of the dielectric layer 024 is not limited in this embodiment of the present application. Optionally, the thickness of the dielectric layer 024 is 10 nanometers or less. For example, the thickness of the dielectric layer 024 is in the range of 2 nanometers to 10 nanometers. It can be seen that when the thickness of the dielectric layer 024 is small, the distance between the first optical waveguide 022 and the electro-optical crystal structure 03 is small, and the distance between the electrode 023 and the electro-optical crystal structure 03 is also small, the optical modulation efficiency of the entire optical waveguide device is high.

[0105] The dielectric layer 024 can be fabricated by depositing a dielectric material (e.g., atomic layer deposition (ALD)). When the thickness of the dielectric layer 024 is 10 nanometers or less, due to the small thickness of the dielectric layer 024, after the dielectric layer 024 is obtained by depositing the dielectric material, the surface of the dielectric layer 024 farther from the substrate 01 is flat, and there is no need to perform a CMP process on the dielectric layer 024. Optionally, when the thickness of the dielectric layer 024 is greater than 10 nanometers, after the dielectric layer 024 is obtained, the dielectric layer 024 can be further subjected to a CMP process to facilitate subsequent bonding to the electro-optical crystal structure 03.

[0106] Optionally, the melting point of the dielectric layer 024 is lower than the melting points of the target structure 02 and the electro-optic crystal structure 03. Note that the target structure 02 includes multiple portions, and the melting point of the target structure 02 may be the melting point of a portion of the multiple portions that is bonded to the electro-optic crystal structure 03. The melting point of the electro-optic crystal structure 03 may be the melting point of a portion of the electro-optic crystal structure 03 that is bonded to the target structure 02.

[0107] Because the melting point of the dielectric layer 024 is lower than the melting points of the target structure 02 and the electro-optic crystal structure 03, the target structure 02, the dielectric layer 024, and the electro-optic crystal structure 03 can be heated as a whole such that when the target structure 02 is bonded to the electro-optic crystal structure 03, the dielectric layer 024 is melted but the target structure 02 and the electro-optic crystal structure 03 are not melted. The melted dielectric layer 024 can effectively bond the target structure 02 and the electro-optic crystal structure 03 together, thereby improving the bonding strength between the target structure 02 and the electro-optic crystal structure 03.

[0108] Additionally, any optical waveguide device provided in this embodiment of the present application may further include a second optical waveguide, and the second optical waveguide is coupled to the first optical waveguide 022. Certainly, the optical waveguide device may not include a second optical waveguide, which is not a limitation in this embodiment of the present application.

[0109] For example, see Figure 12. The optical waveguide device further includes a second optical waveguide 04, which is coupled to the first optical waveguide 022.

[0110] In another example, referring to FIGS. 13, 14, and 15, FIG. 14 is a top view of an optical waveguide device (view of the substrate from the electro-optical crystal structure). FIG. 13 is a schematic diagram of the XX cross section of FIG. 14. FIG. 15 is a schematic diagram of the YY cross section of FIG. 14. FIG. 14 does not show the substrate 01, the insulating layer 021, and the dielectric layer 024. The optical waveguide device shown in FIG. 14 is a Mach-Zehnder optical waveguide device. Alternatively, the optical waveguide device provided in this embodiment of the present application may not be a Mach-Zehnder optical waveguide device, and may be, for example, a push-pull optical waveguide device. This is not limited to this embodiment of the present application. Referring to FIGS. 13, 14, and 15, it can be seen that the optical waveguide device further includes a second optical waveguide 04 located between the substrate 01 and the insulating layer 021.

[0111] The method for fabricating the second optical waveguide 04 may be the same as or different from the method for fabricating the first optical waveguide 022. For example, when the second optical waveguide 04 is fabricated, the second optical waveguide 04 is formed directly on the substrate 01. Then, an insulating layer 021 is formed on the substrate 01 on which the second optical waveguide 04 is formed. Alternatively, as shown in FIG. 16 , an auxiliary layer 104 may be further present between the second optical waveguide 04 and the substrate 01. The material of the auxiliary layer 104 may be the same as or different from the material of the insulating layer 021. Before forming the second optical waveguide 04, the auxiliary layer 104 is first formed on the substrate 01, and then the second optical waveguide 04 is embedded in the surface of the auxiliary layer 104 farther from the substrate 01 using an embedding process. Then, the insulating layer 021 is formed on the substrate 01 on which the second optical waveguide 04 is formed.

[0112] Furthermore, the first light guide 022 is coupled to the second light guide 04. For example, the orthogonal projection of the first light guide 022 onto the substrate 01 and the orthogonal projection of the second light guide 04 onto the substrate 01 at least partially overlap. As shown in FIG. 17 , the orthogonal projection of the first light guide 022 onto the substrate 01 is a projection T1 formed on the substrate 01 (as shown in FIG. 18 ) after light passes through the first light guide 022 by irradiating the substrate 01 with light perpendicular to the substrate 01 from the side of the first light guide 022 remote from the substrate 01. The orthogonal projection of the second light guide 04 onto the substrate 01 is a projection T2 formed on the substrate 01 (as shown in FIG. 18 ) after light passes through the second light guide 04 by irradiating the substrate 01 with light perpendicular to the substrate 01 from the side of the second light guide 04 remote from the substrate 01. The orthogonal projection onto the substrate 01 of the end of the first light guide 022 closer to the second light guide 04 is wedge-shaped (i.e., the end of the orthogonal projection T1 closer to the orthogonal projection T2 in FIG. 18 is wedge-shaped). The orthogonal projection onto the substrate 01 of the end of the second light guide 04 closer to the first light guide 022 is wedge-shaped (i.e., the end of the orthogonal projection T2 closer to the orthogonal projection T1 in FIG. 18 is wedge-shaped).

[0113] Certainly, the first optical waveguide 022 and the second optical waveguide 04 may also be coupled in another manner, which is not limited to this embodiment of the present application. For example, the first optical waveguide 022 and the second optical waveguide 04 may be located in the same layer, and the second optical waveguide 04 may also be embedded in the insulating layer 021. In this case, the first optical waveguide 022 and the second optical waveguide 04 may be coupled in an end-contact manner.

[0114] 12 and 14, the first optical waveguide 022 may be ring-shaped (in this case, the optical waveguide device may be a microring modulator or a microring optical switch, as shown in FIG. 12). The first optical waveguide 022 may also be strip-shaped (as shown in FIG. 14). Therefore, the shape of the first optical waveguide 022 is not limited in this embodiment of the application.

[0115] In some of the above-mentioned methods for manufacturing optical waveguide devices provided in this application, if the bonding between the target structure 02 and the electro-optical crystal structure 03 is the final manufacturing process of the optical waveguide device, the method can be compatible with CMOS processes.

[0116] Furthermore, when the optical waveguide device provided in this embodiment of the present application is fabricated, the corresponding electro-optical crystal structure and the corresponding first optical waveguide can be selected according to the requirements of the optical waveguide device that needs to be fabricated (e.g., requirements such as operating wavelength, bandwidth, modulation efficiency, etc.), and the size of each part in the optical waveguide device can be adjusted accordingly.

[0117] The following describes the size of each part of the optical waveguide device using the following three examples, in which the operating wavelength of the optical waveguide device is 1550 nm and the optical waveguide device is a push-free MZI modulator.

[0118] (1) In Example 1, the structure of the optical waveguide device can be shown in Figures 19, 20, and 21. Figure 20 is a schematic diagram of the MM cross section of Figure 19. Figure 21 is a schematic diagram of the NN cross section of Figure 19. Note that Figure 19 shows only the first optical waveguide 022, the electrode 023, the second optical waveguide 04, and the electro-optical crystal structure 03 of the optical waveguide device, and does not show other structures.

[0119] In Example 1, the material of the first optical waveguide 022 and the second optical waveguide 04 can be a-Si:H, the electro-optic crystal structure 03 includes a support layer 031 and an electro-optic crystal thin film 032, and the material of the electro-optic crystal thin film 032 is lithium niobate. The support layer 031 includes a silicon substrate 0311 and a silicon dioxide layer 0312. The optical waveguide device has low transmission loss at an operating wavelength in the communication band, and the manufacturing method of the optical waveguide device is compatible with a CMOS process.

[0120] Since electro-optic crystal materials have various inhomogeneities and the electro-optic coefficients of the electro-optic crystal materials in various crystal directions are different, the electro-optic coefficient of the electro-optic crystal structure can be adjusted by adjusting the relationship between the crystal directions of the electro-optic crystal materials and other structures in the optical waveguide device.

[0121] For example, the crystal directions of lithium niobate include a crystal direction x, a crystal direction y, and a crystal direction z. The crystal direction x is parallel to the direction x in a three-dimensional coordinate system, the crystal direction y is parallel to the direction y in the three-dimensional coordinate system, and the crystal direction z is parallel to the direction z in the three-dimensional coordinate system. In Example 1, the extension direction of the first optical waveguide 022 can be parallel to the crystal direction y, and the direction of the electric field formed between the electrodes 023 is parallel to the crystal direction z. In this case, the electro-optic coefficient of the electro-optic crystal structure 03 made of lithium niobate is 31 pm / V. Optionally, when the optical waveguide device is as shown in FIGS. 11 and 12 and the electro-optic crystal structure includes a lithium niobate thin film, the crystal direction z of the lithium niobate can be parallel to the direction of the electric field, and both the crystal directions x and y of the lithium niobate are parallel to the lithium niobate thin film.

[0122] Continuing to refer to Figures 19, 20, and 21 in Example 1, the second optical waveguide 04 may be a single-mode optical waveguide. The first optical waveguide 022 has a thickness (its direction perpendicular to the substrate 01) of 220 nanometers and a width (its direction parallel to the direction of the electric field) of 500 nanometers. In the thickness direction, the distance between the first optical waveguide 022 and the second optical waveguide 04 is 100 nanometers, the thickness of the silicon dioxide layer 0312 is 2 micrometers, and the material of the electrode 023 is tungsten.

[0123] The modulation efficiency of the optical waveguide device can be expressed by the product (Vπ·Lπ) of the half-wave voltage (Vπ) and the length (Lπ) of the electro-optic crystal structure in the extension direction of the first optical waveguide 022. A smaller product indicates higher modulation efficiency. In this embodiment of the present application, Vπ·Lπ can be reduced by adjusting the width and thickness of the first optical waveguide located in the junction region, the thickness of the electro-optic crystal thin film, and the spacing between the multiple electrodes for forming the electric field to improve the modulation efficiency of the optical waveguide device. Furthermore, in this embodiment of the present application, parameters such as the thickness and width of the electrode 023 and the spacing between the multiple electrodes can be adjusted to increase the modulation bandwidth of the optical waveguide device. The insertion loss between the first optical waveguide 022 and the second optical waveguide 04 can also be reduced by adjusting the coupling length between these two optical waveguides (e.g., the length of the overlapping portion of the two optical waveguides, such as length C in FIG. 19 ).

[0124] Assume the material properties of lithium niobate, silicon dioxide, single crystal silicon, and tungsten are as follows: the refractive index of lithium niobate is 2.21, the dielectric constant of lithium niobate is 28, the electro-optic coefficient of lithium niobate is 31 pm / V, the refractive index of hydrogenated amorphous silicon is 3.5, the dielectric constant of hydrogenated amorphous silicon is 11.9, the refractive index of silicon dioxide is 1.44, the dielectric constant of silicon dioxide is 3.9, the refractive index of single crystal silicon is 3.45, the dielectric constant of single crystal silicon is 11.9, and the refractive index of tungsten is 2.22 + 4.85i, where i is the imaginary unit. For example, the optical waveguide device parameters for Example 1 are as follows: the width of the first optical waveguide is 1 micrometer, the thickness of the first optical waveguide is 70 nanometers, the included angle between the third and second sides is approximately 70°, the thickness of the electro-optic crystal thin film is 400 nanometers, and the spacing between adjacent electrodes is 4 micrometers. Therefore, the waveguide transmission loss caused by the electrodes is approximately 0.05 decibels per centimeter (dB / cm). In this case, Vπ·Lπ reaches approximately 1.5 volts·centimeter (V·cm), which is smaller than the Vπ·Lπ (2.3 V·cm) of an optical waveguide device obtained by bonding an optical waveguide made of hydrogenated amorphous silicon to a lithium niobate thin film. Furthermore, when the length of the coupling region is greater than approximately 20 micrometers, the coupling efficiency between the first and second optical waveguides can reach more than 99%.

[0125] (2) In Example 2, please refer to Figures 19, 20, and 21 for schematic diagrams of the structure of the optical waveguide device. Unlike Example 1, the material of the first optical waveguide 022 and the second optical waveguide 04 in Example 2 can be silicon nitride (SiN). The first optical waveguide 022 and the second optical waveguide 04 made of silicon nitride can be configured to transmit visible light and near-infrared light.

[0126] For example, when the operating wavelength is 1550 nanometers, the parameters of the optical waveguide device in Example 2 are as follows: the second optical waveguide 04 can be a single-mode optical waveguide having a thickness of 400 nanometers and a width of 1000 nanometers, and the spacing between the first optical waveguide 022 and the second optical waveguide 04 in the thickness direction is 100 nanometers. The refractive index of silicon nitride is 2.0, and the dielectric constant of silicon nitride is 7.9. The width of the first optical waveguide is 1.5 micrometers, the thickness of the first optical waveguide is 300 nanometers, the included angle between the third side and the second side is approximately 70° to 80°, the thickness of the electro-optic crystal thin film is 250 nanometers, and the spacing between adjacent electrodes is 6 micrometers. Thus, the waveguide transmission loss caused by the electrodes is about 0.05 dB / cm, and Vπ·Lπ is about 2.3 V·cm, which is smaller than Vπ·Lπ (6.7 V·cm) of the optical waveguide device obtained by joining an optical waveguide made of silicon nitride and a lithium niobate thin film.

[0127] (3) In Example 3, please refer to Figures 19, 20, and 21 for a schematic diagram of the structure of the optical waveguide device. Unlike Example 1, the electro-optic crystal structure 03 of the optical waveguide device in Example 3 is a bulk electro-optic crystal, such as bulk barium titanate. The electro-optic coefficient of bulk barium titanate is higher than that of a thin film of barium titanate. Therefore, the optical waveguide device in Example 3 has high optical modulation efficiency. The crystal orientation of bulk barium titanate The direction is , can be parallel to the extending direction of the first optical waveguide 022. In this case, the electro-optic coefficient of the electro-optic crystal structure 03 is as high as 1920 pm / V.

[0128] For example, when the operating wavelength is 1550 nm, the optical waveguide device parameters in Example 3 are as follows: the refractive index of bulk barium titanate is 2.4, the dielectric constant of bulk barium titanate is 2400, the electro-optic coefficient of bulk barium titanate is 1920 pm / V, the thickness of the first optical waveguide is 100 nanometers, the width of the first optical waveguide is 1.2 micrometers, and the spacing between adjacent electrodes is 3.2 micrometers. Thus, the waveguide transmission loss caused by the electrodes is about 0.05 dB / cm, and Vπ·Lπ is about 171 V·μm (i.e., 0.017 V·cm), which is smaller than the Vπ·Lπ (0.2 V·cm or 2.3 V·cm) of the optical waveguide device obtained by joining an optical waveguide of the current material with a lithium niobate thin film.

[0129] The above describes the structure of the optical waveguide device provided in the embodiment of this application, and the following describes an example of a method for manufacturing the optical waveguide device.

[0130] For example, Figure 22 is a flowchart of a method for manufacturing an optical waveguide device according to one embodiment of the present application. 14 15 is used as an example to fabricate the optical waveguide device shown in FIG. 22. As shown in FIG. 22, the fabrication method of the optical waveguide device may include the following steps.

[0131] S301: Form a second optical waveguide on a substrate.

[0132] The second optical waveguide can be formed on the substrate in various ways, which is not limited in this embodiment of this application.

[0133] For example, when a second optical waveguide is fabricated, the second optical waveguide is directly formed on a substrate. For example, a waveguide material layer is first formed on a substrate. Then, the waveguide material layer is patterned to obtain the second optical waveguide. The material of the waveguide material layer can be a-Si:H, SiN, TiO2, or the like.

[0134] 16, there may be an additional auxiliary layer 104 between the second optical waveguide 04 and the substrate 01, and the material of the auxiliary layer 104 may be the same as or different from the material of the insulating layer 021. Before the second optical waveguide 04 is formed, the auxiliary layer 104 is first formed on the substrate 01, and then the second optical waveguide 04 is embedded in the surface of the auxiliary layer 104 farther from the substrate 01 by using an embedding process.

[0135] If the second optical waveguide and the first optical waveguide are located in the same layer, S301 does not need to be performed, and the second optical waveguide is formed when the first optical waveguide is formed.

[0136] S302: An insulating layer is formed on the substrate on which the second optical waveguide is formed.

[0137] After the second optical waveguide is formed, an insulating material layer may be formed on the substrate on which the second optical waveguide is formed. Then, a CMP process is performed on the surface of the insulating material layer farther from the substrate to obtain the insulating layer 021 shown in Fig. 23. The material of the insulating material layer may be silicon dioxide.

[0138] S303: Form a first groove in the bonding area of ​​the insulating layer.

[0139] As shown in FIG. 24, a first groove 101 may be formed in the junction area of ​​the insulating layer 021 by etching.

[0140] S304: Embed a first optical waveguide in the first groove, such that a surface of the first optical waveguide remote from the substrate is flush with a surface of the junction region remote from the substrate, and the first optical waveguide is coupled to the second optical waveguide.

[0141] When the first optical waveguide is embedded in the first groove, a waveguide material layer may be first formed on the insulating layer in which the first groove is formed, and the waveguide material layer may cover the entire bonding area. Then, a CMP process is performed on the surface of the waveguide material layer farther from the substrate to remove the portion of the waveguide material layer located outside the first groove, thereby obtaining the first optical waveguide 022 embedded in the first groove, as shown in FIG.

[0142] Since the material of the optical waveguide material layer is different from the material of the insulating layer, when the optical waveguide material layer is subjected to CMP processing, the loss in the insulating layer is not large, and the portion of the optical waveguide material layer located outside the first groove can be effectively removed, resulting in a first optical waveguide whose surface remote from the substrate is flush with the surface of the junction region of the insulating layer remote from the substrate.

[0143] S305: Form a plurality of second grooves in the bonding region of the insulating layer.

[0144] figure 26 As shown in FIG. 1, the first optical waveguide embedded insulating layer A plurality of second grooves 102 may be formed in the bonding region. Note that this embodiment of the present application uses an example in which the first optical waveguide is formed first and then the electrode is formed. Alternatively, the electrode may be formed first and then the first optical waveguide may be formed. In this case, S305 and S306 may be performed first, and then S303 and S304 may be performed.

[0145] S306: Embedding a plurality of electrodes in the plurality of second grooves in a one-to-one correspondence, wherein a surface of at least one electrode facing away from the substrate is flush with a surface of the junction region facing away from the substrate, a first optical waveguide is located between the plurality of electrodes, and the electrodes and the first optical waveguide are arranged one-to-one with a gap therebetween.

[0146] In this embodiment of the present application, an example is used in which the surfaces of the plurality of electrodes farther from the substrate are flush with the surface of the junction region farther from the substrate. When the plurality of electrodes are embedded in the plurality of second grooves in a one-to-one correspondence, a conductive material layer is first formed on the insulating layer in which the plurality of second grooves are formed, and then a CMP process is performed on the surface of the conductive material layer farther from the substrate to remove portions of the conductive material layer located outside the second grooves, thereby obtaining the plurality of electrodes 023 embedded in the plurality of second grooves in a one-to-one correspondence as shown in FIG.

[0147] S307: A dielectric layer is formed on the insulating layer in which the first optical waveguide is embedded.

[0148] As shown in FIG. 28, a dielectric layer 024 may be deposited on the insulating layer 021 in which the first optical waveguide 022 and the electrode 023 are embedded.

[0149] S308: Bonding a surface of the target structure remote from the substrate to an electro-optic crystal structure, the target structure including an insulating layer, a first optical waveguide, a second optical waveguide, a plurality of electrodes, and a dielectric layer.

[0150] The structure obtained in Fig. 28 is the target structure. In S308, as shown in Fig. 29, the surface of the target structure farther from the substrate is bonded to the electro-optic crystal structure 03, and the structure shown in Figs. 14 15. The optical waveguide device shown in FIG. 15 can be obtained.

[0151] For example, the electro-optic crystal structure may include a bulk electro-optic crystal or an electro-optic crystal thin film. If the electro-optic crystal structure includes an electro-optic crystal thin film, the surface of the target structure farther from the substrate may be bonded to the side of the electro-optic crystal structure where the electro-optic crystal thin film is located. Optionally, if the electro-optic crystal structure includes a superimposed support layer and electro-optic crystal thin film, the support layer may be further thinned or removed after S308.

[0152] It can be seen from this manufacturing method that bonding the surface of the target structure remote from the substrate with the electro-optic crystal structure is the final process in the entire method, and the method is compatible with CMOS processes when tungsten is used as the material for the electrodes in the optical waveguide device, which has little impact on the performance of other devices.

[0153] 11 and 12, the method shown in Fig. 22 does not need to include S305 and S306. Also, electrodes may be formed on the substrate before forming an insulating layer on the substrate in S302 (or before S301), and an insulating layer may be formed on the substrate with the electrodes formed thereon in S302. The electro-optic crystal structure may include a support layer and an electro-optic crystal thin film superimposed on each other, the support layer including a conductive material, and when the surface of the target structure remote from the substrate is bonded to the electro-optic crystal structure in S308, the surface of the target structure remote from the substrate may be bonded to the side of the electro-optic crystal structure where the electro-optic crystal thin film is located.

[0154] In this application, the terms "first," "second," etc. are merely intended to be descriptive and should not be understood as indicating or implying relative importance. Unless expressly stated otherwise, the term "at least one" refers to one or more, and the term "plurality" refers to two or more. The term "and / or" simply describes an associative relationship between related objects and indicates that three relationships may exist. For example, A and / or B can represent three cases: only A exists, both A and B exist, or only B exists.

[0155] Different types of embodiments, such as method embodiments and component embodiments, provided in the embodiments of this application should be cross-referenced. This is not limited to the embodiments of this application. The processing order of the method embodiments provided in the embodiments of this application can be adjusted appropriately, and processing can be added or deleted accordingly based on the situation. Any method that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application falls within the protection scope of this application. Therefore, details will not be described again.

[0156] In the corresponding embodiments provided in this application, it should be understood that the disclosed device may be implemented in other ways. The above description is merely an optional implementation of this application, and the protection scope of this application is not limited thereto. Any equivalent modifications or replacements that can be easily thought of by those skilled in the art within the technical scope disclosed in this application shall fall within the protection scope of this application. Therefore, the protection scope of this application shall be subject to the protection scope of the claims.

Claims

1. An optical waveguide device, the optical waveguide device having a substrate, a target structure, and an electro-optic crystal structure; the target structure includes an insulating layer and a first optical waveguide; a bonding region of the insulating layer having a first groove, the first optical waveguide being embedded in the first groove, a surface of the first optical waveguide remote from the substrate being flush with a surface of the bonding region remote from the substrate; the electro-optic crystal structure is bonded to a face of the target structure remote from the substrate; a cross section of the first optical waveguide perpendicular to an extending direction of the first optical waveguide has a first side and a second side facing each other, the first side being closer to the substrate and the second side being farther from the substrate, and the first groove is formed to have an inverted trapezoidal cross section such that the length of the second side is longer than the length of the first side; Optical waveguide devices.

2. 2. The optical waveguide device according to claim 1, wherein the cross section further has a third side connected to the first side and the second side, and the included angle between the third side and the second side is in the range of [60°, 80°].

3. 10. The optical waveguide device of claim 1, wherein the electro-optic crystal structure comprises a bulk electro-optic crystal or an electro-optic crystal thin film.

4. 2. The optical waveguide device of claim 1, wherein the electro-optic crystal structure has a superimposed support layer and an electro-optic crystal thin film, and the surface of the target structure remote from the substrate is bonded to the side of the electro-optic crystal structure where the electro-optic crystal thin film is located.

5. 2. The optical waveguide device of claim 1, wherein the bonding region further has a plurality of second grooves, the target structure further has a plurality of electrodes embedded in the plurality of second grooves in a one-to-one correspondence, the surface of at least one electrode facing away from the substrate being flush with the surface of the bonding region facing away from the substrate, the first optical waveguide being located between the plurality of electrodes, and the plurality of electrodes and the plurality of first optical waveguides in the optical waveguide device being arranged in a one-to-one relationship with a gap therebetween.

6. The optical waveguide device further includes an electrode located between the substrate and the insulating layer; 2. The optical waveguide device of claim 1, wherein the electro-optic crystal structure comprises a support layer and an electro-optic crystal thin film superimposed on each other, the support layer comprising a conductive material, and the surface of the target structure remote from the substrate is bonded to the side of the electro-optic crystal structure on which the electro-optic crystal thin film is located.

7. 6. The optical waveguide device according to claim 5, wherein the material of the electrodes includes at least one of aluminum, tungsten, titanium, titanium nitride, and indium tin oxide.

8. The optical waveguide device of claim 5, wherein the material of the electrode includes tungsten.

9. 2. The optical waveguide device of claim 1, wherein the target structure further comprises a dielectric layer located between the junction region of the insulating layer and the electro-optic crystal structure, the dielectric layer being configured to prevent metal ions on the side where the insulating layer is located from diffusing into the electro-optic crystal structure.

10. 10. The optical waveguide device according to claim 9, wherein the thickness of the dielectric layer is 10 nanometers or less.

11. 10. The optical waveguide device according to claim 9, wherein the melting point of the dielectric layer is lower than the melting point of the target structure and the melting point of the electro-optic crystal structure.

12. 2. The optical waveguide device of claim 1, further comprising a second optical waveguide located between the substrate and the insulating layer, the first optical waveguide being coupled to the second optical waveguide.

13. an orthogonal projection of the first optical waveguide onto the substrate and an orthogonal projection of the second optical waveguide onto the substrate at least partially overlap; an orthogonal projection of an end of the first optical waveguide closer to the second optical waveguide onto the substrate is wedge-shaped; and an orthogonal projection of an end of the second optical waveguide closer to the first optical waveguide onto the substrate is wedge-shaped.

13. The optical waveguide device according to claim 12.

14. the material of the first optical waveguide comprises hydrogenated amorphous silicon, the electro-optic crystal structure comprises a lithium niobate thin film, and Vπ·Lπ is less than 2.3 volts-centimeters, where Vπ represents a half-wave voltage of the optical waveguide device and Lπ represents a length of the electro-optic crystal structure in the extension direction of the first optical waveguide; or the material of the first optical waveguide comprises silicon nitride, the electro-optic crystal structure comprises a lithium niobate thin film, and Vπ·Lπ is less than 6.7 volt-centimeters, where Vπ represents a half-wave voltage of the optical waveguide device and Lπ represents a length of the electro-optic crystal structure in the extension direction of the first optical waveguide; or the material of the first optical waveguide comprises hydrogenated amorphous silicon, the electro-optic crystal structure comprises bulk barium titanate, Vπ·Lπ is less than 0.2 volts-centimeters, Vπ represents a half-wave voltage of the optical waveguide device, and Lπ represents a length of the electro-optic crystal structure in the extension direction of the first optical waveguide; 2. The optical waveguide device according to claim 1.

15. An optical chip comprising the optical waveguide device according to any one of claims 1 to 14.

16. A communication device comprising the optical chip of claim 15.

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