Optical chip structure, method for manufacturing optical chip, and communication module

Abstract

An optical chip (10) structure, a method for manufacturing the optical chip (10), and a communication module. The optical chip (10) structure comprises a substrate (106), a cladding layer (105), a photoelectric modulation layer (103), and a photodetector (104). A first waveguide (102a) and a second waveguide (102b) connected to each other are provided in the cladding layer (105); the substrate (106) and the cladding layer (105) are stacked in a first direction; the photoelectric modulation layer (103) is arranged on the side of the cladding layer (105) away from the substrate (106); the projection of the first waveguide (102a) in the first direction partially overlaps the photoelectric modulation layer (103); and the photodetector (104) is located on one side of the second waveguide (102b) in the first direction, and the height of the photodetector (104) is greater than the height of an optical conduction region (105a). The optical chip (10) decouples the requirement that the height of the optical conduction region (105a) must be consistent with the height of the photodetector (104), and the heights of the optical conduction region (105a) and the photodetector (104) can be comprehensively considered, so that the evanescent wave coupling transmission efficiency between the first waveguide (102a) and the photoelectric modulation layer (103) and the working efficiency of the photodetector (104) both can be optimized, thereby improving the optical communication transmission efficiency and quality of the optical chip (10).

Description

Optical chip structure, optical chip preparation method and communication module

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of China on March 29, 2024, with application number 202410389109.2, and priority to the Chinese patent application entitled “Optical chip structure, optical chip preparation method and communication module”, all contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of optical communication technology, and in particular to an optical chip structure, an optical chip preparation method, and a communication module. Background Art

[0003] In optical communication equipment, passive and active devices usually need to be set in the same chip to achieve photonic integration, which can be used in scenarios such as high-baud-rate communication with integrated transceiver.

[0004] In recent years, lithium niobate photoelectric modulators, which use optical waveguides formed by etching lithium niobate thin films, have improved the modulation efficiency of integrated optical chips and significantly increased their size and integration compared to standalone lithium niobate crystal modulators. However, the coupling efficiency (coupling distance) between the optical waveguide and the modulator, and the height of the photodetector, interact with each other, making it difficult to fabricate an optical chip that simultaneously achieves both coupling and photodetection efficiency. Summary of the Invention

[0005] The present application provides an optical chip structure, an optical chip preparation method and a communication module. By separating the structural correlation between the detector and the modulator, the evanescent wave coupling transmission efficiency between the first waveguide and the photoelectric modulation layer and the working efficiency of the photoelectric detector can be optimized, thereby improving the optical communication transmission efficiency and quality of the optical chip.

[0006] In a first aspect, the present application provides an optical chip structure, comprising a substrate, a cladding, an optoelectronic modulation layer, and a photodetector, wherein a first waveguide and a second waveguide connected to each other are disposed in the cladding;

[0007] The substrate and the cladding are stacked along a first direction, the electro-optical modulation layer is provided on a side of the first waveguide facing away from the substrate, a projection of the first waveguide along the first direction partially overlaps with the electro-optical modulation layer, a light conducting region is interposed between the first waveguide and the electro-optical modulation layer, and the light conducting region is part of the cladding;

[0008] The cladding has a receiving cavity on one side of the second waveguide along the first direction. The photodetector is at least partially located in the receiving cavity. Along the first direction, the height of the photodetector is greater than the height of the light conducting region.

[0009] The optical chip provided in this embodiment decouples the association that the height of the light conduction area and the height of the photodetector must be consistent. The heights of the light conduction area and the photodetector can be comprehensively considered, so that the evanescent wave coupling transmission efficiency between the first waveguide and the photoelectric modulation layer and the working efficiency of the photodetector can be optimized, thereby improving the optical communication transmission efficiency and quality of the optical chip.

[0010] In a possible implementation, there is a spacing distance between the photodetector and the photoelectric modulation layer, which can prevent the protruding photodetector from causing installation interference with the photoelectric modulation layer during preparation, and is beneficial to the production and preparation of the photoelectric modulation layer.

[0011] In one possible implementation, the spacing distance is greater than 200 nanometers; taking into account the mounting accuracy of micro-transfer printing, the spacing distance between the photodetector and the photoelectric modulation layer can be greater than 200 nanometers, which can prevent installation interference between the micro-transfer print head and the photodetector.

[0012] In one possible implementation, along the first direction, the height of the photodetector protruding from the bottom surface of the photoelectric modulation layer toward the substrate side is in the range of 0-10 (excluding 0 and including 10) microns, while ensuring the photoelectric detection performance, the manufacturing cost of the photodetector is reduced as much as possible.

[0013] In a possible implementation, the photoelectric modulation layer includes at least one of a lithium niobate film, a lithium tantalate film, a Group III-V semiconductor film, and an organic film material.

[0014] In a possible implementation, the material of the photodetector includes at least one of silicon germanium, Group III-V semiconductors, and organic materials.

[0015] In one possible implementation, the first waveguide and the second waveguide have the same thickness along the first direction, so that the first waveguide and the second waveguide can be prepared on the same layer. The optical signal can be transmitted at the same height when transmitted in the two waveguides, thereby improving transmission efficiency.

[0016] In a possible implementation, along the first direction, the first waveguide and the second waveguide are at the same distance from the substrate, and optical signals can be transmitted at the same height when transmitted in the two waveguides, thereby improving transmission efficiency.

[0017] In one possible implementation, a third waveguide is further included, wherein the first waveguide includes an adjacent first waveguide region and a second waveguide region, the second waveguide includes an adjacent third waveguide region and a fourth waveguide region, the first waveguide region and the third waveguide region are parallel, the second waveguide region and the fourth waveguide region intersect and converge to be connected to the third waveguide, and the optical signal is transmitted to the external optical fiber through the third waveguide, and the optical signal is transmitted with the first waveguide and the second waveguide respectively within the same optical chip.

[0018] In a possible implementation, the first waveguide and the electro-optical modulation layer are connected by a gradient coupling connection and / or a grating coupling connection to improve the signal transmission efficiency between the first waveguide and the electro-optical modulation layer.

[0019] In a possible implementation, the optical chip structure further includes a connection layer, where the connection layer is located between the electro-optical modulation layer and the cladding layer, and is used to connect the electro-optical modulation layer and the cladding layer.

[0020] In a possible implementation, a thickness of the light conduction region between the electro-optical modulation layer and the first waveguide along the first direction is in a range of 0 to 3 micrometers.

[0021] In a second aspect, the present application provides a method for preparing an optical chip, which is used to prepare an optical chip structure as described in any one of the above items, comprising the following steps:

[0022] forming a substrate;

[0023] forming a first cladding layer on the surface of the substrate;

[0024] forming a second cladding, a first waveguide, and a second waveguide on the first cladding, wherein the second cladding, the first waveguide, and the second waveguide are located in the same layer, and the first waveguide and the second waveguide are connected;

[0025] forming a third cladding layer on the second cladding layer and the first waveguide, and forming a photodetector on the second waveguide, wherein the height of the photodetector is higher than that of the third cladding layer;

[0026] forming a photoelectric modulation film, defining a target area on the photoelectric modulation film, and partially interrupting the edge of the target area so that the target area and the main body of the photoelectric modulation film are connected via the breakpoints, wherein the main body of the photoelectric modulation film is the area outside the target area;

[0027] A micro-transfer print head fixes the target area of ​​the photoelectric modulation film, separates the target area of ​​the photoelectric modulation film and the main body of the photoelectric modulation film, avoids the photodetector and transfers the target area to the surface of the third cladding layer and above the first waveguide, and connects the third cladding layer and the target area to form a photoelectric modulation layer.

[0028] The optical chip preparation method described in this embodiment can prepare the photoelectric modulation layer above the first waveguide by micro-transfer, without the need for simultaneous preparation with the photodetector, thereby decoupling the relationship between the height of the light conduction area and the height of the photodetector, and the prepared optical chip can comprehensively consider the height of the light conduction area and the photodetector, so that the evanescent wave coupling transmission efficiency between the first waveguide and the photoelectric modulation layer and the working efficiency of the photodetector can be optimized, thereby improving the optical communication transmission efficiency and quality of the optical chip.

[0029] In one possible implementation, a connection layer is formed on the target area of ​​the photoelectric modulation film, and the connection layer and the third cladding layer are connected to form the photoelectric modulation layer, and the connection strength between the photoelectric modulation layer and the cladding layer is improved by the connection layer.

[0030] In one possible implementation, after the step of connecting the connecting layer and the third cladding layer to form the photoelectric modulation layer, the photoelectric modulation layer is patterned and etched to form a gradient coupling structure between the photoelectric modulation layer and the first waveguide, thereby improving the coupling efficiency of the optical signal transmitted between the first waveguide and the photoelectric modulation layer.

[0031] In a third aspect, the present application provides a communication module comprising an optical fiber and an optical chip, wherein the optical chip comprises any of the optical chip structures described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG1 is a schematic diagram of signal transmission in an optical communication system according to an embodiment of the present application;

[0033] FIG2 is a schematic diagram of the structure of an optical communication system provided in an embodiment of the present application;

[0034] FIG3 is a first schematic cross-sectional view of a partial area of ​​an optical chip provided in an embodiment of the present application;

[0035] FIG4 is a second schematic cross-sectional view of a partial area of ​​an optical chip provided in an embodiment of the present application;

[0036] FIG5 is a third schematic cross-sectional view of a partial area of ​​an optical chip provided in an embodiment of the present application;

[0037] FIG6 is a fourth schematic cross-sectional view of a partial area of ​​an optical chip provided in an embodiment of the present application;

[0038] FIG7 is a fifth schematic cross-sectional view of a partial area of ​​an optical chip provided in an embodiment of the present application;

[0039] FIG8 is a schematic top view of a waveguide provided in an embodiment of the present application;

[0040] FIG9 a is a schematic top view of the electro-optical modulation layer and a portion of the first waveguide along the opposite direction of the first direction in FIG4 ;

[0041] FIG9 b is a second schematic top view of the electro-optical modulation layer and a portion of the first waveguide along the opposite direction to the first direction in FIG4 ;

[0042] FIG9 c is a third schematic top view of the electro-optical modulation layer and a portion of the first waveguide along the opposite direction to the first direction in FIG4 ;

[0043] FIG9 d is a fourth schematic top view of the electro-optical modulation layer and a portion of the first waveguide along the opposite direction to the first direction in FIG4 ;

[0044] FIG10 is a schematic diagram of a grating coupling structure of an electro-optical modulation layer and a portion of a first waveguide provided in an embodiment of the present application;

[0045] FIG11 is a schematic diagram of the connection layer structure provided in an embodiment of the present application;

[0046] FIG12 is a schematic diagram of the process steps of the optical chip manufacturing method provided in an embodiment of the present application;

[0047] FIG13 is a schematic diagram of an optical chip preparation process according to an embodiment of the present application;

[0048] FIG14 is a schematic diagram of the main body of the photoelectric modulation film provided in an embodiment of the present application;

[0049] FIG15 is a schematic diagram of the patterning and etching process in the optical chip preparation method provided in an embodiment of the present application;

[0050] FIG16 is a schematic diagram of the conductive structure of the optical chip provided in an embodiment of the present application. DETAILED DESCRIPTION

[0051] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0052] For ease of understanding, the English abbreviations and related technical terms involved in the embodiments of this application are explained and described below.

[0053] It should be clear that the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0054] The terms used in the embodiments of the present application are for the purpose of describing specific embodiments only and are not intended to limit the present application. The singular forms "a", "an", "the" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

[0055] It should be understood that the term "and / or" as used herein is simply a term used to describe the existence of three possible relationships between related objects. For example, "A and / or B" can represent the existence of A alone, the existence of both A and B, and the existence of B alone. Furthermore, the character " / " in this document generally indicates that the related objects are in an "or" relationship.

[0056] The word "if," as used herein, may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to the determination" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)," depending on the context.

[0057] It should be understood that the terms “first”, “second”, etc. used in this application are only used for the purpose of distinguishing descriptions, and cannot be understood as indicating or implying relative importance, nor can they be understood as indicating or implying an order.

[0058] In the description of this application, the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limiting this application.

[0059] When used in this application, "within the range of...", unless it is specifically stated that the end value is not included, it is assumed that both end values ​​of the range are included. For example, in the range of 1 to 5, the two values ​​1 and 5 are included.

[0060] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "install", "connect" and "connect" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, a conflicting connection or an integrated connection. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0061] The present application provides an optical communication system. Referring to Figures 1 and 2, Figure 1 is a schematic diagram of signal transmission in an optical communication system according to an embodiment of the present application, and Figure 2 is a schematic diagram of the structure of an optical communication system according to an embodiment of the present application. The optical communication system may include an optical chip 10 and a conversion chip (not numbered in the figure). The optical chip 10 is provided with a light-emitting component 101, an optical waveguide 102, an electro-optical modulation layer 103, and a photodetector 104. It should be noted that the optical chip in Figure 1 only illustrates a partial structure. A cladding layer and wiring structures may also be provided above the electro-optical modulation layer 103 and the photodetector 104. The port of the optical waveguide 102 of the optical chip 10 is connected to an optical fiber 20, which may be at least one of an input fiber and an output fiber. The optical signal emitted by the light-emitting component 101 can pass through the optical waveguide 102 into the output fiber of the optical fiber 20, and then enter another optical chip 10 through the output fiber, pass through the optical waveguide of the other optical chip, and enter the photodetector 104 of the other optical chip, thereby achieving optical communication transmission between two electronic devices.

[0062] 2 , one end of the optical chip 10 shown in FIG2 is connected to an optical fiber for transmitting optical signals, and the other end is connected to a conversion chip for processing and generating electrical signals.

[0063] The optical chip 10 may include an optoelectronic modulation layer 103. The optical communication device may be connected to an output optical fiber. After modulating the optical signal to be modulated, the modulated optical signal may be emitted through the output optical fiber. The optical signal to be modulated may be provided by a light source provided outside the optical chip 10, or by a light-emitting component 101 in the optical chip 10. The light-emitting component 101 may be, for example, a laser diode. The optical chip 10 may include a photodetector 104. The optical communication device may be connected to an input optical fiber. An optical signal transmitted by another optical chip may be transmitted to the optical chip 10 via the input optical fiber. The photodetector 104 may generate a corresponding electrical signal based on the optical signal to process the electrical signal. The conversion chip may include a driver module. The driver module may be connected to the optoelectronic modulation layer 103 to provide a modulation signal so that the optoelectronic modulation layer 103 modulates the optical signal to be modulated using the modulation signal, and loads the modulation signal, which is an electrical signal, onto the optical signal to be modulated. The conversion chip may further include a trans-impedance amplifier (TIA), which may be connected to the photodetector 104 to amplify the electrical signal generated by the photodetector 104 .

[0064] The conversion chip may include an optical digital signal processing (oDSP) module. The oDSP module may be connected to the driving module to control the driving module to generate a modulation signal. The oDSP module may be connected to the transimpedance amplifier to control the transimpedance amplifier to amplify the electrical signal and process the amplified electrical signal.

[0065] In the optical chip 10 structure, the electro-optical modulation layer 103 may be a lithium niobate electro-optical modulator. The electro-optical modulation layer 103 may be formed by etching a lithium niobate thin film to form an optical waveguide or other structure. This improves the modulation efficiency of the integrated optical chip and, compared to a standalone lithium niobate crystal modulator, increases its integration density and reduces its volume. However, referring to FIG3 , the optical waveguide 102 may include a first waveguide 102a and a second waveguide 102b. The first waveguide 102a is located below the electro-optical modulation layer 103. An evanescent wave coupling transmission structure is formed between the first waveguide 102a and the electro-optical modulation layer 103. Signals may pass through an optical conductive region 105a between the first waveguide 102a and the electro-optical modulation layer 103. The optical conductive region 105a may be a portion of the cladding 105, such as the dashed-line portion shown in FIG3 , to form a signal transmission channel between the first waveguide 102a and the electro-optical modulation layer 103. The photodetector 104 may be located above the second waveguide 102 b , and the photodetector 104 may be in contact with the second waveguide 102 b , and the optical signal transmitted by the second waveguide 102 b may be transmitted to the photodetector 104 .

[0066] Heterogeneous integration of optoelectronic and microelectronic devices made of different materials is a technology that integrates optoelectronic and microelectronic devices. This technology can combine the advantages of different materials, achieve complementary benefits, and improve chip performance and functionality. In heterogeneous integration of optoelectronic and microelectronic devices made of different materials, these devices can be integrated according to a specific structure and system design. Heterogeneous integration of optoelectronic and microelectronic devices offers advantages such as high integration density, low cost, and low power consumption.

[0067] During the fabrication of the optical chip 10, after depositing a portion of the cladding 105, the first waveguide 102a, the second waveguide 102b, and the photodetector 104, the top surfaces of the cladding 105 and the photodetector 104 are generally polished, and the electro-optical modulation layer 103 is then formed on the polished surface. During this process, the height of the light-conducting region 105a between the first waveguide 102a and the electro-optical modulation layer 103 is the same as the height of the photodetector 104. However, the height of the light-conducting region 105a should not be too large, otherwise the evanescent wave coupling structure between the first waveguide 102a and the electro-optical modulation layer 103 will be too high, affecting the optical signal transmission efficiency between the first waveguide 102a and the electro-optical modulation layer 103. Similarly, the height of the photodetector 104 should not be too small, otherwise the performance of the photodetector 104 will be degraded. Therefore, under the existing preparation process, the height of the evanescent wave coupling structure between the first waveguide 102a and the optoelectronic modulation layer 103 and the height of the photodetector 104 interfere with each other, making it difficult to prepare an optical chip 10 with a smaller light conduction area 105a and a larger photodetector 104, resulting in the inability to optimize the performance of the optical chip 10.

[0068] To address the aforementioned issues, the present application provides an optical chip 10 structure. Referring to FIG4 , the optical chip 10 may include a substrate 106, a cladding 105, an electro-optical modulation layer 103, and a photodetector 104. A first waveguide 102a and a second waveguide 102b are disposed within the cladding 105. Referring to FIG1 , one end of the first waveguide 102a may be connected to the light-emitting component 101, and the other end extends to connect to one end of the second waveguide 102b and converge into the same waveguide structure.

[0069] In one embodiment, the first waveguide 102a and the second waveguide 102b can be at the same height within the cladding 105. The first waveguide 102a and the second waveguide 102b are at the same height in the thickness direction of the cladding 105 (the height direction shown in FIG4 ). During fabrication, the first waveguide 102a and the second waveguide 102b can be fabricated in the same layer, which simplifies the fabrication process, reduces manufacturing complexity, and lowers manufacturing costs. It can also improve the optical transmission efficiency between the first waveguide 102a and the second waveguide 102b (located on different optical chips 10). During fabrication, the first waveguide 102a and the second waveguide 102b can be fabricated in the same layer. In one embodiment, the cladding 105 can be made of a combination of one or more materials selected from silicon dioxide, silicon nitride, and silicon oxynitride.

[0070] In one embodiment, the first waveguide 102a and the second waveguide 102b may be silicon waveguides, silicon nitride waveguides, indium phosphide waveguides, silicon carbide waveguides, or organic material waveguides. The third waveguide in the following embodiments may also be silicon waveguides, silicon nitride waveguides, indium phosphide waveguides, silicon carbide waveguides, or organic material waveguides.

[0071] The substrate 106 and the cladding layer 105 are stacked along a first direction 10a, which is consistent with the height direction shown in Figure 4. The electro-optical modulation layer 103 is disposed on a side of the cladding layer 105 facing away from the substrate 106. The substrate 106, the cladding layer 105, and the electro-optical modulation layer 103 can be stacked along the first direction 10a.

[0072] The projection of the first waveguide 102a along the first direction 10a may partially overlap with the electro-optical modulation layer 103. In one embodiment, the projection of the first waveguide 102a along the first direction 10a may completely cover the electro-optical modulation layer 103. A light-conducting region 105a is located between the first waveguide 102a and the electro-optical modulation layer 103. The light-conducting region 105a is a portion of the cladding 105 located between the first waveguide 102a and the electro-optical modulation layer 103. An evanescent wave coupling structure is formed between the first waveguide 102a and the electro-optical modulation layer 103. Evanescent wave coupling refers to the laser energy transfer phenomenon caused by the interaction when laser light propagates through an interface or medium. The optical signal transmitted in the first waveguide 102a can be transmitted to the electro-optical modulation layer 103 via the evanescent wave coupling structure.

[0073] The cladding 105 has a receiving cavity 105b on one side of the second waveguide 102b along the first direction 10a. (It should be noted that the receiving cavity 105b described in this embodiment of the present application refers to the groove structure provided on the cladding 105 itself. However, in the overall optical chip 10 structure, the receiving cavity 105b may be filled with a photodetector 104, so the groove structure cannot be directly seen.) The photodetector 104 may be partially located within the receiving cavity 105b. The photodetector 104 is in contact with the second waveguide 102b, and the optical signal transmitted by the second waveguide 102b can be directly received by the photodetector 104. In one embodiment, along the first direction 10a, the height h2 of the photodetector 104 is greater than the height h1 of the light-conducting region 105a.

[0074] In one embodiment, the photodetector 104 and the second waveguide 102b may be in contact at the bottom at one end in the opposite direction of the first direction 10a, or may be separated by a cladding 105 of a certain thickness. On the premise that the optical signal in the second waveguide 102b can be transmitted to the photodetector 104, there are multiple options for the connection relationship between the photodetector 104 and the second waveguide 102b.

[0075] Among them, when preparing the optical chip 10 described in the present application, the photoelectric modulation layer 103 can be attached to the top of the light conduction area 105a by micro-transfer printing or other methods. When attaching, the raised photodetector 104 can be avoided. Therefore, when preparing the photoelectric modulation layer 103, it is not necessary to grind the upper surface of the light conduction area 105a and the upper surface of the photodetector 104 flat. The height h2 of the photodetector 104 does not need to be consistent with the height h1 of the light conduction area 105a. The height h2 of the photodetector 104 and the height h1 of the light conduction area 105a can be designed separately according to the performance requirements of the optical chip 10. , so that the height h2 of the photodetector 104 can be greater than the height h1 of the light conduction region 105a, and the height h1 of the light conduction region 105a in the prepared optical chip 10 structure can be maintained within a suitable range, so that a more efficient evanescent wave coupling structure is formed between the first waveguide 102a and the photoelectric modulation layer 103; and the height h2 of the photodetector 104 in the prepared optical chip 10 structure can be within a suitable range. In one embodiment, the height h2 of the photodetector 104 can be in the range of 3 microns to 10 microns, so that the photodetector 104 has better performance.

[0076] The optical chip 10 provided in the embodiment of the present application decouples the association that the height of the light conduction area 105a and the height of the photodetector 104 must be consistent. The heights of the light conduction area 105a and the photodetector 104 can be comprehensively considered, so that the evanescent wave coupling transmission efficiency between the first waveguide 102a and the photoelectric modulation layer 103 and the working efficiency of the photodetector 104 can be optimized, thereby improving the optical communication transmission efficiency and quality of the optical chip 10.

[0077] In some possible embodiments, as shown in Figures 4 and 5 , a spacing space 103a is defined between the photodetector 104 and the photoelectric modulation layer 103. The left side of the spacing space 103a in Figure 4 may be the photoelectric modulation layer 103, the right side may be the photodetector 104, and the bottom side may be the upper surface of the cladding layer 105. The spacing space 103a separates the photodetector 104 from the photoelectric modulation layer 103. The spacing distance between the photodetector 104 and the photoelectric modulation layer 103 prevents the protruding photodetector 104 from interfering with the installation of the photoelectric modulation layer 103 during fabrication, facilitating the production of the photoelectric modulation layer 103.

[0078] In one embodiment, the spacing distance between the photodetector 104 and the photoelectric modulation layer 103 is greater than 200 nanometers. In one embodiment (an embodiment of a corresponding preparation method is provided below), the photoelectric modulation layer 103 can be bonded to the cladding 105 by micro-transfer printing. Taking into account the mounting accuracy of micro-transfer printing, the spacing distance between the photodetector 104 and the photoelectric modulation layer 103 can be greater than 200 nanometers, which can prevent the installation interference between the micro-transfer printing print head and the photodetector 104. In one embodiment, with the development of micro-transfer printing technology and the improvement of mounting accuracy, the spacing distance between the photodetector 104 and the photoelectric modulation layer 103 can be further reduced to reduce the volume of the optical chip 10. The spacing distance can be the shortest distance in the left-right direction of the spacing space 103a in Figure 5, such as the spacing distance h3 in Figure 5. By limiting the spacing distance h3 to a suitable range, the protruding photodetector 104 will not interfere with the preparation of the photoelectric modulation layer 103, and the distance between the photodetector 104 and the photoelectric modulation layer 103 will not be too large, ensuring that the volume of the optical chip 10 is within a small suitable range.

[0079] In some possible embodiments, referring to FIG. 5 , along the first direction 10a, the height h4 of the photodetector 104 protruding from the bottom surface 1025 of the photoelectric modulation layer 103 facing the substrate 106 can be in the range of 0 to 10 microns (excluding 0 and including 10), for example, 5 microns. This reduces the manufacturing cost of the photodetector 104 as much as possible while ensuring the photoelectric detection performance.

[0080] In some possible implementations, as shown in Figure 3, the substrate 106 may be a silicon layer made of silicon material, which may serve as the base layer of the optical chip 10. The cladding layer 105 may be formed on the silicon layer by deposition or other techniques.

[0081] In one embodiment, the cladding layer 105 may be made of a mixture of one or more materials such as silicon dioxide, silicon nitride, and silicon oxynitride, and may serve as an insulating layer.

[0082] In one embodiment, the photoelectric modulation layer 103 may include a lithium niobate film. The photoelectric modulation layer 103 may be a film layer made of a lithium niobate material. In one embodiment, the photoelectric modulation layer 103 may also be at least one of a lithium tantalate film, a Group III-V semiconductor film, and an organic film. The lithium tantalate film, the Group III-V semiconductor film, and the organic film may all be materials having optical signal modulation capabilities. In one embodiment, the Group III-V semiconductor film refers to a film made of a compound semiconductor material composed of elements from the third period (i.e., Group B) and the fifth period (i.e., Group A) of the periodic table, and may include an indium phosphide film and a gallium arsenide film.

[0083] In one embodiment, the photodetector 104 may be a silicon-germanium photodetector, which is made of materials such as germanium and silicon. In another embodiment, the photodetector 104 may also be made of at least one of a Group III-V semiconductor and an organic material. Group III-V semiconductors refer to compound semiconductor materials composed of elements from the third period (i.e., Group B) and the fifth period (i.e., Group A) of the periodic table, and may include indium phosphide films and gallium arsenide films. It should be noted that both Group III-V semiconductors and organic materials may be materials capable of detecting optical signals.

[0084] In one embodiment, as shown in FIG6 , along the first direction 10a, the first waveguide 102a and the second waveguide 102b can have the same thickness. The thickness of each of the first waveguide 102a and the second waveguide 102b can be h5. During fabrication, the first waveguide 102a and the second waveguide 102b can be fabricated on the same layer. In one embodiment, the thickness h5 of the first waveguide 102a and the second waveguide 102b can be in a range from 100 nanometers to 10 microns. In one embodiment, the first waveguide 102a and the second waveguide 102b can be made of the same or different materials. In one embodiment, the thickness of the first waveguide 102a and the second waveguide 102b can be the same or different. For example, the thickness of a silicon waveguide can be in a range from 220 nanometers to 3 microns, the thickness of a silicon nitride waveguide can be in a range from 200 nanometers to 800 nanometers, and the thickness of a silicon dioxide waveguide can be approximately 8 microns.

[0085] In one embodiment, as shown in FIG7 , along the first direction 10a, the first waveguide 102a and the second waveguide 102b are at the same distance from the substrate 106. The distance h6 between the first waveguide 102a and the second waveguide 102b and the substrate 106 can both be deposited on the substrate 106. During fabrication, a cladding structure can be deposited on the substrate 106, and then the first waveguide 102a and the second waveguide 102b are formed on the same cladding structure. In one embodiment, the distance h6 between the first waveguide 102a and the second waveguide 102b and the substrate 106 can be in a range of 2 microns to 5 microns. In one embodiment, the distance h6 between the first waveguide 102a and the second waveguide 102b and the substrate 106 can be different. In one embodiment, the distance h6 between the first waveguide 102a and the second waveguide 102b and the substrate 106 can be the same, so that they can be fabricated on the same layer, facilitating faster fabrication.

[0086] It should be noted that the two identical parts described in the embodiment of the present application may have some errors taking into account factors such as design and processing errors, and the errors may be within 20%.

[0087] In one embodiment, referring to FIG8 , FIG8 shows a schematic top view of the optical waveguide 102. The top view direction of FIG8 is the opposite direction to the first direction 10a in FIG2 . The optical waveguide 102 further includes a third waveguide 102c. The first waveguide 102a includes a first waveguide region 1021 and a second waveguide region 1022 adjacent to each other. The second waveguide region 102b includes a third waveguide region 1023 and a fourth waveguide region 1024 adjacent to each other. The first waveguide region 1021 and the second waveguide region 1022 are integrally formed. The second waveguide region 1022 is inclined from one end adjacent to the first waveguide region 1021 to the other end toward the third waveguide 102c. The third waveguide region 1023 and the fourth waveguide region 1024 are integrally formed. The fourth waveguide region 1024 is inclined from one end adjacent to the third waveguide region 1023 to the other end toward the third waveguide 102c.

[0088] The third waveguide region 1023 and the fourth waveguide region 1024 are connected at one end close to the third waveguide 102 c , and intersect and converge into the third waveguide 102 c .

[0089] In one embodiment, the first waveguide region 1021 and the third waveguide region 1023 may be parallel to each other.

[0090] In one embodiment, referring to FIG4 and FIG9a, FIG9a is a schematic top view of the electro-optical modulation layer and a portion of the first waveguide along the direction opposite to the first direction in FIG4. In one embodiment, a gradient coupling connection structure and / or a grating coupling connection structure may be formed between the first waveguide 102a and the electro-optical modulation layer 103. Referring to FIG9a and FIG9b, FIG9a and FIG9b illustrate a gradient coupling structure. Specifically, referring to FIG4 and FIG9a, the width of the portion of the first waveguide 102a where the projection along the first direction 10a overlaps with the electro-optical modulation layer 103 gradually decreases along a second direction 10b, wherein the second direction 10b is one of the extension directions of the first waveguide 102a, and the width of the electro-optical modulation layer 103 gradually decreases along a direction opposite to the second direction 10b.

[0091] The second direction 10b is perpendicular to the first direction 10a, and the portion of the first waveguide 102a parallel to the second waveguide 102b is also parallel to the second direction 10b. Along the second direction 10b, the width of the first waveguide 102a gradually decreases, with the width direction of the gradually decreasing portion being perpendicular to the second direction 10b. This portion also overlaps with the electro-optical modulation layer 103 along the first direction 10a. Correspondingly, the width of the electro-optical modulation layer 103 gradually decreases in the direction opposite to the second direction 10b, with the width direction of the electro-optical modulation layer 103 being perpendicular to the second direction 10b. The first waveguide 102a and the electro-optical modulation layer 103 form a relative tapered coupling structure at corresponding locations. This tapered coupling structure can improve the coupling efficiency of optical signals transmitted between the first waveguide 102a and the electro-optical modulation layer 103.

[0092] In one embodiment, referring to Figure 9b, Figure 9b is a second schematic top view of the electro-optical modulation layer and a portion of the first waveguide along a direction opposite to the first direction in Figure 4. In this embodiment, the second direction 10b is opposite to the second direction in Figure 9a. The first waveguide 102a has two extension directions. In this embodiment, the second direction 10b is aligned with the other extension direction of the first waveguide 102a. The gradient coupling structure exhibited by the first waveguide 102a and the electro-optical modulation layer 103 in this embodiment is opposite to the gradient coupling structure shown in Figure 9a. In one embodiment, regardless of the direction in which the widths of the first waveguide 102a and the electro-optical modulation layer 103 decrease, the first waveguide 102a and the electro-optical modulation layer 103 form a relative gradient coupling structure in the overlapping portion, thereby improving the coupling efficiency of the optical signal transmitted from the first waveguide 102a to the electro-optical modulation layer 103.

[0093] In one embodiment, referring to FIG. 9c , FIG. 9c is a schematic top view of the electro-optical modulation layer and a portion of the first waveguide along the direction opposite to the first direction in FIG. 4 , in the portion where the electro-optical modulation layer 103 overlaps with the first waveguide 102a along the first direction 10a, either end of the electro-optical modulation layer 103 can form a gradient coupling connection structure with the first waveguide 102a. In one embodiment, both ends of the electro-optical modulation layer 103 can form a gradient coupling connection structure with the first waveguide 102a. Furthermore, the gradient coupling connection structures formed at both ends are not necessarily related. In FIG. 9c , at the end in the positive direction of the second direction 10b, the width of the electro-optical modulation layer 103 can gradually decrease along the positive direction of the second direction 10b, while the corresponding width of the first waveguide 102a can remain unchanged or gradually increase along the positive direction of the second direction 10b.

[0094] In one embodiment, at one end in the positive direction of the second direction 10b, the width of the electro-optical modulation layer 103 may gradually increase along the positive direction of the second direction 10b, and the corresponding width of the first waveguide 102a may remain unchanged or gradually decrease along the positive direction of the second direction 10b. In one embodiment, at one end in the positive direction of the second direction 10b, the width of the electro-optical modulation layer 103 may gradually decrease along the positive direction of the second direction 10b, and the corresponding width of the first waveguide 102a may remain unchanged or gradually increase along the positive direction of the second direction 10b. In one embodiment, at one end in the positive direction of the second direction 10b, the width of the electro-optical modulation layer 103 may remain unchanged along the positive direction of the second direction 10b, and the corresponding width of the first waveguide 102a may gradually increase or decrease along the positive direction of the second direction 10b.

[0095] In one embodiment, at the end in the opposite direction of the second direction 10b, the width of the electro-optical modulation layer 103 may gradually increase along the positive direction of the second direction 10b, and the corresponding width of the first waveguide 102a may remain unchanged or gradually decrease along the positive direction of the second direction 10b. In one embodiment, at the end in the opposite direction of the second direction 10b, the width of the electro-optical modulation layer 103 may gradually decrease along the positive direction of the second direction 10b, and the corresponding width of the first waveguide 102a may remain unchanged or gradually increase along the positive direction of the second direction 10b. In one embodiment, at the end in the opposite direction of the second direction 10b, the width of the electro-optical modulation layer 103 may remain unchanged along the positive direction of the second direction 10b, and the corresponding width of the first waveguide 102a may gradually increase or decrease along the positive direction of the second direction 10b.

[0096] In one embodiment, as shown in Figure 9c , the electro-optical modulation layer 103 forms a tapered coupling connection structure with the first waveguide 102a at both ends in the second direction 10b . The portion of the first waveguide 102a that overlaps with the electro-optical modulation layer 103 along the first direction is integrally connected. In one embodiment, as shown in Figure 9d , which is a top view of the electro-optical modulation layer and a portion of the first waveguide along the direction opposite to the first direction in Figure 4 , the portion of the first waveguide 102a that overlaps with the electro-optical modulation layer 103 along the first direction is disconnected. These two disconnected portions of the first waveguide 102a allow for coupled transmission of optical signals through the electro-optical modulation layer 103.

[0097] In one embodiment, as shown in FIG10 , the first waveguide 102a may have a grating structure disposed on its surface in the positive direction of the first direction 10a, or may have a grating structure disposed on its surface in the opposite direction of the first direction 10a. In one embodiment, the electro-optical modulation layer 103 may also have a grating structure disposed on its surface in the positive direction of the first direction 10a, or may have a grating structure disposed on its surface in the opposite direction of the first direction 10a. In one embodiment, a grating structure is disposed on at least one of the first waveguide 102a and the electro-optical modulation layer 103 to form a grating coupling structure.

[0098] In some possible embodiments, as shown in Figure 11, the optical chip 10 further includes a connecting layer 107, which is located between the photoelectric modulation layer 103 and the cladding 105. The material of the connecting layer 107 is the same as that of the cladding 105 to better connect the photoelectric modulation layer 103 and the cladding 105.

[0099] In one embodiment, the connecting layer 107 can be a thin film made of the same material as the cladding 105, so as to connect the cladding 105 and the photoelectric modulation layer 103 through homogeneous bonding, and while connecting the photoelectric modulation layer 103 and the cladding 105, it will not affect the evanescent wave coupling structure between the photoelectric modulation layer 103 and the cladding 105.

[0100] In one embodiment, the thickness of the light conduction region 105a between the photoelectric modulation layer 103 and the first waveguide 102a along the first direction 10a (see height h1 in Figure 4) can be in the range of 0 to 3 microns, so that an evanescent wave coupling structure is formed between the photoelectric modulation layer 103 and the first waveguide 102a, and the first waveguide 102a can transmit optical signals to the photoelectric modulation layer 103.

[0101] In one embodiment, as shown in FIG16 , the optical chip 10 further includes a conductive structure 108. The cladding 105 may extend above the electro-optical modulation layer 103 and the photodetector 104, so that the cladding 105 can wrap around the electro-optical modulation layer 103 and the photodetector 104. The conductive structure 108 may include metal vias and connection structures (such as solder joints or pins) provided on the upper outer surface of the cladding 105. There may be multiple conductive structures 108, and the conductive structures 108 pass through portions of the cladding 105 to electrically connect to the electro-optical modulation layer 103 and the photodetector 104.

[0102] In some possible implementations, referring to FIG. 12 and FIG. 13 , the following steps are included:

[0103] Step S100: forming a substrate 106, which may be a silicon layer structure;

[0104] Step S200: forming a first cladding layer 1051 on the surface of the substrate 106. The first cladding layer 1051 may be made of silicon dioxide. Silicon dioxide may be formed on a silicon layer by deposition or other techniques.

[0105] Step S300: forming a second cladding layer 1052, a first waveguide 102a, and a second waveguide 102b on the first cladding layer 1051; the second cladding layer 1052, the first waveguide 102a, and the second waveguide 102b are located in the same layer, and the first waveguide 102a and the second waveguide 102b are connected;

[0106] Part of the second cladding layer 1052 may be spaced between the first waveguide 102a and the second waveguide 102b. As shown in FIG8 , the optical waveguide 102 further includes a third waveguide 102c. The first waveguide 102a includes a first waveguide region 1021 and a second waveguide region 1022 adjacent to each other, and the second waveguide 102b includes a third waveguide region 1023 and a fourth waveguide region 1024 adjacent to each other. The first waveguide region 1021 and the second waveguide region 1022 are integrally formed, with the second waveguide region 1022 tilting from one end adjacent to the first waveguide region 1021 to the other end toward the third waveguide 102c. The third waveguide region 1023 and the fourth waveguide region 1024 are integrally formed, with the fourth waveguide region 1024 tilting from one end adjacent to the third waveguide region 1023 to the other end toward the third waveguide 102c. The third waveguide region 1023 and the fourth waveguide region 1024 are connected at one end close to the third waveguide 102 c , and intersect and converge into the third waveguide 102 c .

[0107] It should be noted that, in the embodiment of the present application, the formation time of the first cladding 1051 and the second cladding 1052 are different, but the first cladding 1051 and the second cladding 1052 can become an integral structure after formation, and there may be no obvious interface between the first cladding 1051 and the second cladding 1052. The dotted line between the first cladding 1051 and the second cladding 1052 in Figure 13 is only for distinction, and does not limit the presence of an interface between the first cladding 1051 and the second cladding 1052. The first cladding 1051 and the second cladding 1052 can be an integrated integral structure.

[0108] Step S400: forming a third cladding layer 1053 on the second cladding layer 1052 and the first waveguide 102a, and forming a photodetector 104 on the second waveguide 102b, wherein the height of the photodetector 104 is higher than the third cladding layer 1053;

[0109] Similarly, in the embodiment of the present application, the second cladding 1052 and the third cladding 1053 are formed at different times, but the second cladding 1052 and the third cladding 1053 can become an integral structure after formation, and there may not be an obvious interface between the second cladding 1052 and the third cladding 1053. The dotted line between the second cladding 1052 and the third cladding 1053 in Figure 13 is only for distinction, and does not limit the presence of an interface between the second cladding 1052 and the third cladding 1053. The second cladding 1052 and the third cladding 1053 can be an integrated integral structure.

[0110] Step S500: Forming a photoelectric modulator film. Referring to FIG. 14 , the photoelectric modulator film has a predetermined size. A target region 103 c is defined on the photoelectric modulator film. The edges of the target region 103 c are partially broken. The target region 103 c and the main body 103 b of the photoelectric modulator film are separated by breakpoints 103 e and connected by connecting portions 103 d between the breakpoints 103 e. The main body 103 b of the photoelectric modulator film is the area outside the target region 103 c.

[0111] Step S600: The micro-transfer print head fixes the target area 103c of the photoelectric modulator film, separating the target area 103c of the photoelectric modulator film from the main body 103b of the photoelectric modulator film. Since the target area 103c and the main body 103b are disconnected by multiple breakpoints 103e, and the connecting portion 103d between the breakpoints 103e is connected to the main body 103b and the target area 103c, the connecting portion 103d is relatively weak, and the micro-transfer print head can be used to pull the connecting portion 103d to break the target area 103c and the main body 103b.

[0112] After the target area 103c is separated from the main body 103b, the micro-transfer print head carries the target area 103c, avoids the photodetector 104 and transfers the target area 103c to the surface of the third cladding 1053 and above the first waveguide 102a, connecting the third cladding 1053 and the target area 103c to form the photoelectric modulation layer 103.

[0113] In some possible embodiments, in step S600, after the step of separating the target area 103c of the photoelectric modulation film and the main body 103b of the photoelectric modulation film, a connecting layer 107 is formed on the target area 103c of the photoelectric modulation film. The material of the connecting layer 107 is the same as the material of the third cladding 1053. The connecting layer 107 and the third cladding 1053 on one side of the target area 103c are connected to form the photoelectric modulation layer 103. The structure of the formed optical chip 10 can refer to Figure 11.

[0114] In one embodiment, referring to FIG. 15 , after the step of connecting the third cladding layer 1053 and the target region 103c to form the electro-optical modulation layer 103, the electro-optical modulation layer 103 is patterned and etched, for example, along the dotted lines of the target region 103c in FIG. Patterning may involve preparing a photoresist with a specific shape on the electro-optical modulation layer 103, and then etching away the structure outside the photoresist through an etching process, simultaneously removing the photoresist and leaving the shape of the target region. Patterning and etching can form a gradient coupling structure between the electro-optical modulation layer 103 and the first waveguide 102a.

[0115] In one embodiment, the step of forming the second cladding 1052, the first waveguide 102a, and the second waveguide 102b on the first cladding 1051 further includes: forming a partial region of the first waveguide 102a with a width gradually decreasing along a second direction 10b, where the second direction 10b is one of the extension directions of the first waveguide 102a;

[0116] After the step of connecting the third cladding layer 1053 and the target area 103c to form the photoelectric modulation layer 103, the width of the photoelectric modulation layer 103 is adjusted to gradually decrease in the opposite direction of the second direction 10b to form a structure as shown in Figure 9a, Figure 9b, Figure 9c or Figure 9d.

[0117] The present application also provides a specific embodiment of a communication module, as shown in FIG1 and FIG2 , which includes an optical fiber 20 and an optical chip 10 . The optical chip may include the optical chip structure described in any of the above embodiments.

[0118] Referring to Figures 1 and 2, Figure 1 is a schematic diagram of signal transmission in an optical communication system according to an embodiment of the present application, and Figure 2 is a schematic diagram of the structure of an optical communication system according to an embodiment of the present application. The optical communication system may include an optical chip 10 and a conversion chip (not numbered in the figure). The optical chip 10 is provided with a light-emitting component 101, an optical waveguide 102, an electro-optical modulation layer 103, and a photodetector 104. It should be noted that the optical chip in Figure 1 only illustrates a partial structure; cladding and other structures such as wiring may also be provided above the electro-optical modulation layer 103 and the photodetector 104. The port of the optical waveguide 102 of the optical chip 10 is connected to an optical fiber 20, which may be at least one of an input fiber and an output fiber. The optical signal emitted by the light-emitting component 101 can pass through the optical waveguide 102 into the output fiber of the optical fiber 20, and then enter another optical chip 10 through the output fiber, pass through the optical waveguide of the other optical chip, and enter the photodetector 104 of the other optical chip, thereby achieving optical communication transmission between two electronic devices.

[0119] 2 , one end of the optical chip 10 shown in FIG2 is connected to an optical fiber for transmitting optical signals, and the other end is connected to a conversion chip for processing and generating electrical signals.

[0120] The optical chip 10 may include an optoelectronic modulation layer 103. The optical communication device may be connected to an output optical fiber. After modulating the optical signal to be modulated, the modulated optical signal may be emitted through the output optical fiber. The optical signal to be modulated may be provided by a light source provided outside the optical chip 10, or by a light-emitting component 101 in the optical chip 10. The light-emitting component 101 may be, for example, a laser diode. The optical chip 10 may include a photodetector 104. The optical communication device may be connected to an input optical fiber. An optical signal transmitted by another optical chip may be transmitted to the optical chip 10 via the input optical fiber. The photodetector 104 may generate a corresponding electrical signal based on the optical signal to process the electrical signal. The conversion chip may include a driver module. The driver module may be connected to the optoelectronic modulation layer 103 to provide a modulation signal so that the optoelectronic modulation layer 103 modulates the optical signal to be modulated using the modulation signal, and loads the modulation signal, which is an electrical signal, onto the optical signal to be modulated. The conversion chip may further include a trans-impedance amplifier (TIA), which may be connected to the photodetector 104 to amplify the electrical signal generated by the photodetector 104 .

[0121] The conversion chip may include an optical digital signal processing (oDSP) module. The oDSP module may be connected to the driving module to control the driving module to generate a modulation signal. The oDSP module may be connected to the transimpedance amplifier to control the transimpedance amplifier to amplify the electrical signal and process the amplified electrical signal.

[0122] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. An optical chip structure, characterized in that: The invention comprises a substrate, a cladding, a photoelectric modulation layer and a photodetector, wherein a first waveguide and a second waveguide connected to each other are arranged in the cladding; The substrate and the cladding are stacked along a first direction, the electro-optical modulation layer is provided on a side of the first waveguide facing away from the substrate, a projection of the first waveguide along the first direction partially overlaps with the electro-optical modulation layer, a light conducting region is interposed between the first waveguide and the electro-optical modulation layer, and the light conducting region is part of the cladding; The cladding has a receiving cavity on one side of the second waveguide along the first direction. The photodetector is at least partially located in the receiving cavity. Along the first direction, the height of the photodetector is greater than the height of the light conducting region.

2. The optical chip structure according to claim 1, characterized in that: There is a spacing distance between the photodetector and the photoelectric modulation layer.

3. The optical chip structure according to claim 2, characterized in that: The separation distance is greater than 200 nanometers.

4. The optical chip structure according to any one of claims 1 to 3, characterized in that: The photoelectric modulation layer has a bottom surface on a side facing the substrate. Along the first direction, the photodetector protrudes from the bottom surface by a height ranging from 0 to 10 micrometers.

5. The optical chip structure according to any one of claims 1 to 4, characterized in that: The photoelectric modulation layer includes at least one of a lithium niobate film, a lithium tantalate film, a Group III-V semiconductor film, and an organic film material.

6. The optical chip structure according to any one of claims 1 to 5, characterized in that: The material of the photodetector includes at least one of silicon germanium, Group III-V semiconductors and organic materials.

7. The optical chip structure according to any one of claims 1 to 6, characterized in that: The first waveguide and the second waveguide have the same thickness along the first direction.

8. The optical chip structure according to any one of claims 1 to 7, characterized in that: Along the first direction, the first waveguide and the second waveguide are at the same distance from the substrate.

9. The optical chip structure according to any one of claims 1 to 8, characterized in that: It also includes a third waveguide, the first waveguide includes a first waveguide area and a second waveguide area adjacent to each other, the second waveguide includes a third waveguide area and a fourth waveguide area adjacent to each other, the first waveguide area and the third waveguide area are parallel to each other, and the second waveguide area and the fourth waveguide area intersect and converge to connect with the third waveguide.

10. The optical chip structure according to any one of claims 1 to 9, characterized in that: The first waveguide and the electro-optical modulation layer are connected by a gradient coupling connection and / or a grating coupling connection.

11. The optical chip structure according to any one of claims 1 to 10, characterized in that: The optical chip structure further includes a connection layer, which is located between the electro-optical modulation layer and the cladding layer, and is used to connect the electro-optical modulation layer and the cladding layer.

12. The optical chip structure according to any one of claims 1 to 11, characterized in that: A thickness of the light conducting region between the electro-optical modulation layer and the first waveguide along the first direction is in a range of 0 to 3 micrometers.

13. The optical chip structure according to any one of claims 1 to 12, characterized in that: The height of the photodetector along the first direction is in a range from 3 micrometers to 10 micrometers.

14. A method for preparing an optical chip, for preparing the optical chip structure according to any one of claims 1 to 13, characterized in that: The steps include: forming a substrate; forming a first cladding layer on the surface of the substrate; forming a second cladding, a first waveguide, and a second waveguide on the first cladding, wherein the second cladding, the first waveguide, and the second waveguide are located in the same layer, and the first waveguide and the second waveguide are connected; forming a third cladding layer on the second cladding layer and the first waveguide, and forming a photodetector on the second waveguide, wherein the height of the photodetector is higher than that of the third cladding layer; forming a photoelectric modulation film, defining a target area on the photoelectric modulation film, and partially interrupting the edge of the target area so that the target area and the main body of the photoelectric modulation film are connected via the breakpoints, wherein the main body of the photoelectric modulation film is the area outside the target area; A micro-transfer print head fixes the target area of ​​the photoelectric modulation film, separates the target area of ​​the photoelectric modulation film and the main body of the photoelectric modulation film, avoids the photodetector and transfers the target area to the surface of the third cladding layer and above the first waveguide, and connects the third cladding layer and the target area to form a photoelectric modulation layer.

15. The method for preparing an optical chip according to claim 14, wherein: A connection layer is formed on a target region of the electro-optical modulation film, and the connection layer and the third cladding layer are connected to form the electro-optical modulation layer.

16. The method for preparing an optical chip according to claim 14 or 15, characterized in that: After the step of connecting the connection layer and the third cladding layer to form the electro-optical modulation layer, the electro-optical modulation layer is patterned and etched to form a graded coupling structure between the electro-optical modulation layer and the first waveguide.

17. A communication module, characterized in that: The optical chip comprises an optical fiber and an optical chip, wherein the optical chip comprises the optical chip structure according to any one of claims 1 to 13.

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