Optical transceiver and manufacturing method therefor

Abstract

Provided in the embodiments of the present disclosure are an optical transceiver and a manufacturing method therefor. The manufacturing method comprises: providing a base, the base comprising a substrate, a buried oxide layer and a lithium niobate layer which are successively stacked, and the base comprising a light modulation area and a light detection area; etching the lithium niobate layer located in the light modulation area so as to form a thin film lithium niobate waveguide; removing the lithium niobate layer and part of the buried oxide layer which are located in the light detection area, so as to form recesses, the bottoms of the recesses exposing the substrate; and forming a light absorption layer in the recesses, the thin film lithium niobate waveguide being used for modulating an optical signal and outputting the modulated optical signal, and the light absorption layer being used for detecting the modulated optical signal and converting the modulated optical signal into an electric signal.

Description

Optical transceiver and manufacturing method thereof

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based on the Chinese patent application with application number 202311064631.5 and application date of August 21, 2023, and claims the priority of the Chinese patent application. The entire content of the Chinese patent application is hereby introduced into this application as a reference. Technical Field

[0003] The present disclosure relates to the field of integrated optical devices, and in particular to an optical transceiver and a manufacturing method thereof. Background Art

[0004] Lithium niobate exhibits photorefractive, nonlinear, electro-optic, acousto-optic, piezoelectric, and thermoelectric effects, and is widely used in applications such as acousto-optic modulation, electro-optic modulation, and wavelength conversion. Compared to conventional lithium niobate (LN) materials, lithium niobate on insulator (LNOI) achieves a refractive index contrast of approximately 0.7 between the thin-film lithium niobate layer and the buried oxide layer by introducing a buried oxide layer (i.e., silicon dioxide). Therefore, thin-film lithium niobate can be used to fabricate optical devices with smaller size, stronger electro-optic interaction, and higher response speed, and has become an important platform for integrated photonics.

[0005] However, because lithium niobate lacks the physical mechanisms for luminescence and photoelectric conversion, thin-film lithium niobate-based integrated photonic circuits lack both a light source and a photodetector to convert optical signals into electrical signals. This lack of a light source and a photodetector prevents thin-film lithium niobate integrated photonic circuits from achieving on-chip electrical / optical and optical / electrical conversion, and has become a major bottleneck in the practical application of thin-film lithium niobate integrated photonic technology.

[0006] Summary of the Invention

[0007] In view of this, embodiments of the present disclosure provide an optical transceiver and a method for manufacturing the same.

[0008] To achieve the above objectives, the technical solution of the present disclosure is implemented as follows:

[0009] In a first aspect, an embodiment of the present disclosure provides a method for manufacturing an optical transceiver, the method comprising:

[0010] Providing a substrate, the substrate comprising a substrate, a buried oxide layer, and a lithium niobate layer stacked in sequence; the substrate comprising a light modulation region and a light detection region;

[0011] Etching the lithium niobate layer located in the light modulation region to form a thin film lithium niobate waveguide;

[0012] removing the lithium niobate layer and a portion of the buried oxide layer located in the light detection region to form a groove; the bottom of the groove exposes the substrate;

[0013] A light absorbing layer is formed in the groove; wherein the thin film lithium niobate waveguide is used to modulate the optical signal and output the modulated optical signal; the light absorbing layer is used to detect the modulated optical signal and convert the modulated optical signal into an electrical signal.

[0014] In some embodiments, etching the lithium niobate layer in the light modulation region to form a thin film lithium niobate waveguide includes:

[0015] Etching the lithium niobate layer located in the light modulation region in a direction perpendicular to the substrate to form a thin film lithium niobate waveguide; wherein the etching depth of the lithium niobate layer is less than the thickness of the lithium niobate layer;

[0016] After etching the lithium niobate layer located in the light modulation region to form a thin film lithium niobate waveguide, the manufacturing method further includes:

[0017] A plurality of first metal electrodes are formed on the lithium niobate layer.

[0018] In some embodiments, etching the lithium niobate layer in the light modulation region to form a thin film lithium niobate waveguide includes:

[0019] Etching the lithium niobate layer in the light modulation region in a direction perpendicular to the substrate to form a thin-film lithium niobate waveguide and expose the buried oxide layer; wherein the etching depth of the lithium niobate layer is the same as the thickness of the lithium niobate layer;

[0020] After etching the lithium niobate layer located in the light modulation region to form a thin film lithium niobate waveguide, the manufacturing method further includes:

[0021] A plurality of first metal electrodes are formed on the buried oxide layer.

[0022] In some embodiments, the substrate further comprises a light coupling region, wherein the light coupling region is located between the light modulation region and the light detection region;

[0023] The lithium niobate layer and a portion of the substrate located in the optical coupling region are removed to form an air cavity between the remaining substrate and the buried oxide layer; wherein the buried oxide layer located in the optical coupling region forms a suspended waveguide; the suspended waveguide is used to couple the modulated optical signal to the light absorption layer.

[0024] In some embodiments, removing the lithium niobate layer and a portion of the buried oxide layer located in the light detection region to form a recess includes:

[0025] removing the lithium niobate layer located in the light detection region to expose the buried oxide layer;

[0026] The buried oxide layer located in the light detection region is etched along a direction perpendicular to the substrate to form a groove; wherein the depth of the groove is the same as the thickness of the buried oxide layer.

[0027] In some embodiments, after removing the lithium niobate layer and a portion of the buried oxide layer located in the light detection region to form a groove, the manufacturing method further includes:

[0028] Doping the substrate on two opposite sides of the bottom of the groove perpendicular to the optical signal transmission direction to form a first doping region and a second doping region respectively;

[0029] After forming the light absorbing layer in the groove, the manufacturing method further includes:

[0030] removing the buried oxide layer located in the light detection region to expose surfaces of the first doped region and the second doped region;

[0031] A second metal electrode and a third metal electrode are formed on the first doping region and the second doping region respectively.

[0032] In some embodiments, the material of the substrate includes silicon;

[0033] The material of the light absorbing layer includes germanium or Group III-V materials.

[0034] In a second aspect, an embodiment of the present disclosure provides an optical transceiver, comprising: a lithium niobate modulator, an optical coupling structure, and a photodetector located on a substrate, wherein the optical coupling structure is located between the lithium niobate modulator and the photodetector; the substrate comprises a substrate, a buried oxide layer, and a lithium niobate layer stacked in sequence;

[0035] The lithium niobate modulator comprises: the substrate, a buried oxide layer located on the substrate, and a thin-film lithium niobate waveguide located on the buried oxide layer; the thin-film lithium niobate waveguide is formed by etching the lithium niobate layer;

[0036] The optical coupling structure includes: a silicon layer, a suspended waveguide, and an air cavity located between the silicon layer and the suspended waveguide; the silicon layer is formed by etching a portion of the substrate; the suspended waveguide is formed by the buried oxide layer;

[0037] The photodetector includes: the substrate and a light absorbing layer located on the substrate; wherein the thin-film lithium niobate waveguide is used to modulate the optical signal and output the modulated optical signal; the suspended waveguide is used to couple the modulated optical signal to the light absorbing layer; the light absorbing layer is used to detect the modulated optical signal and convert the modulated optical signal into an electrical signal.

[0038] In some embodiments, the lithium niobate modulator further comprises:

[0039] A first metal electrode is in contact with the thin film lithium niobate waveguide or the first metal electrode is in contact with the buried oxide layer.

[0040] In some embodiments, the photodetector further comprises:

[0041] a first doping region and a second doping region, wherein the first doping region and the second doping region are formed by doping the substrate; and the light absorbing layer is located between the first doping region and the second doping region;

[0042] A second metal electrode and a third metal electrode, wherein the second metal electrode and the third metal electrode are respectively located on the first doping region and the second doping region.

[0043] The present disclosure provides an optical transceiver and a method for manufacturing the same. The method comprises: providing a substrate, the substrate comprising a substrate, a buried oxide layer, and a lithium niobate layer stacked in sequence; the substrate comprising an optical modulation region and an optical detection region; etching the lithium niobate layer in the optical modulation region to form a thin-film lithium niobate waveguide; removing the lithium niobate layer and a portion of the buried oxide layer in the optical detection region to form a groove; exposing the substrate at the bottom of the groove; and forming a light absorption layer in the groove; wherein the thin-film lithium niobate waveguide is used to modulate an optical signal and output the modulated optical signal; and the light absorption layer is used to detect the modulated optical signal and convert the modulated optical signal into an electrical signal. In the embodiment of the present disclosure, the base includes a substrate, a buried oxide layer and a lithium niobate layer stacked in sequence. The lithium niobate layer located in the light modulation area is etched to form a thin film lithium niobate waveguide, and the lithium niobate layer and the buried oxide layer located in the light detection area are etched away to form a groove exposing the substrate, and then a light absorption layer is formed in the groove, so that the lithium niobate modulator and the photodetector can be integrated on the same substrate, and the thin film lithium niobate waveguide is used to modulate the light signal and output the modulated light signal to the light absorption layer. The light absorption layer detects the modulated light signal and converts the modulated light signal into an electrical signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] FIG1 is a schematic flow chart of a method for manufacturing an optical transceiver according to an embodiment of the present disclosure;

[0045] FIG2A is a schematic structural diagram of an optical transceiver provided in an embodiment of the present disclosure;

[0046] FIG2B is a side view of an optical transceiver provided in an embodiment of the present disclosure;

[0047] 3A to 3H are schematic cross-sectional views of a lithium niobate modulator during the manufacturing process according to an embodiment of the present disclosure;

[0048] 4A to 4H are schematic cross-sectional views of an optical transceiver during the manufacturing process according to an embodiment of the present disclosure;

[0049] FIG5 is a schematic diagram of the three-dimensional structure of a photodetector provided in an embodiment of the present disclosure;

[0050] FIG6 is a schematic cross-sectional view of a photodetector and lithium niobate modulation according to an embodiment of the present disclosure;

[0051] FIG7 is a schematic diagram of the cross-sectional structure of an optical transceiver provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0052] The following will clearly and completely describe the technical solutions in the embodiments of the present disclosure in conjunction with the embodiments of the present disclosure and the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present disclosure.

[0053] In the following description, numerous specific details are provided to provide a more thorough understanding of the present disclosure. However, it will be apparent to those skilled in the art that the present disclosure can be practiced without one or more of these details. In other instances, certain technical features known in the art are not described to avoid confusion with the present disclosure; that is, all features of actual embodiments are not described herein, nor are well-known functions and structures described in detail.

[0054] In the drawings, the sizes of layers, regions, elements and their relative sizes may be exaggerated for clarity. Like reference numerals denote like elements throughout.

[0055] It should be understood that when an element or layer is referred to as being "on, adjacent to, connected to, or coupled to" another element or layer, it may be directly on, adjacent to, connected to, or coupled to the other element or layer, or there may be intervening elements or layers. In contrast, when an element is referred to as being "directly on, directly adjacent to, directly connected to, or directly coupled to" another element or layer, there may be no intervening elements or layers. It should be understood that although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers, and / or parts, these elements, components, regions, layers, and / or parts should not be limited by these terms. These terms are merely used to distinguish one element, component, region, layer, or part from another element, component, region, layer, or part. Therefore, without departing from the teachings of the present disclosure, the first element, component, region, layer, or part discussed below may be represented as a second element, component, region, layer, or part. However, when the second element, component, region, layer, or part is discussed, it does not necessarily mean that the first element, component, region, layer, or part exists in the present disclosure.

[0056] Spatially relative terms such as "under," "beneath," "below," "under," "above," "above," etc., may be used herein for convenience of description to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that in addition to the orientations shown in the figures, the spatially relative terms are intended to include different orientations of the device in use and operation. For example, if the device in the drawings is flipped, then the elements or features described as "under the other elements" or "under it" or "under it" will be oriented as "on" the other elements or features. Thus, the exemplary terms "under" and "under" may include both upper and lower orientations. The device may be oriented otherwise (rotated 90 degrees or in other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0057] The purpose of the terms used herein is only to describe specific embodiments and is not intended to limit the present disclosure. When used herein, the singular forms "a", "an", and "the" are intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "comprising" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0058] In order to fully understand the present disclosure, detailed steps and detailed structures will be presented in the following description to illustrate the technical solution of the present disclosure. The preferred embodiments of the present disclosure are described in detail below. However, in addition to these detailed descriptions, the present disclosure may also have other implementation methods.

[0059] Silicon photonics is a next-generation technology based on silicon and silicon-based substrate materials such as silicon-germanium / silicon (SiGe / Si) and silicon-on-insulator (SOI), utilizing existing complementary metal oxide semiconductor (CMOS) processes for the development and integration of optical devices. It combines the ultra-large-scale, ultra-high-precision manufacturing characteristics of integrated circuit technology with the ultra-high speed and ultra-low power consumption advantages of photonic technology, and is a disruptive technology that addresses the failure of Moore's Law. This combination, thanks to the scalability of semiconductor wafer manufacturing, enables large-scale production and reduces costs. Optical modulators and detectors are both core active devices in silicon-based photonics.

[0060] Pure silicon optical modulators based on the carrier dispersion effect have a bandwidth limit of approximately 80 GHz, and currently offer little room for improvement. Lithium niobate thin-film optical modulators have a theoretical bandwidth of up to 500 GHz, offering very attractive development prospects and experiencing rapid growth both domestically and internationally in recent years. III-V and silicon-germanium photodetectors have a higher bandwidth limit, with reported bandwidths reaching 265 GHz. Therefore, integrating lithium niobate thin-film optical modulators and photodetectors into photonic chips will be a technological trend, effectively addressing the current bandwidth limitations. Furthermore, heterogeneous integration of photonic, electronic, and laser chips through three-dimensional stacking will further enhance overall chip performance.

[0061] In the prior art, the main method for integrating light sources and detectors into thin-film lithium niobate integrated photonic circuits is hybrid integration, such as bonding. However, the lithium niobate modulators and photodetectors obtained using this hybrid integration approach face challenges in reliability and manufacturability.

[0062] In view of this, embodiments of the present disclosure provide an optical transceiver and a method for manufacturing the same.

[0063] Referring to FIG1 , FIG1 is a flow chart of a method for manufacturing an optical transceiver provided by an embodiment of the present disclosure. As shown in FIG1 , an embodiment of the present disclosure provides a method for manufacturing an optical transceiver, the manufacturing method comprising:

[0064] Step S101: providing a substrate, the substrate comprising a substrate, a buried oxide layer, and a lithium niobate layer stacked in sequence; the substrate comprising a light modulation region and a light detection region;

[0065] Step S102: etching the lithium niobate layer in the light modulation region to form a thin film lithium niobate waveguide;

[0066] Step S103: removing the lithium niobate layer and part of the buried oxide layer in the light detection area to form a groove; the bottom of the groove exposes the substrate;

[0067] Step S104: forming a light absorbing layer in the groove; wherein the thin film lithium niobate waveguide is used to modulate the optical signal and output the modulated optical signal; the light absorbing layer is used to detect the modulated optical signal and convert the modulated optical signal into an electrical signal.

[0068] In the disclosed embodiments, after forming a thin-film lithium niobate waveguide, the lithium niobate layer and buried oxide layer located in the light detection region are etched away to form a groove exposing the substrate, and a light absorption layer is then formed within the groove. This allows the lithium niobate modulator and photodetector to be integrated on the same substrate. The thin-film lithium niobate waveguide is used to modulate the optical signal and output the modulated optical signal to the light absorption layer, which detects the modulated optical signal and converts it into an electrical signal. In the disclosed embodiments, the thin-film lithium niobate waveguide and the photoelectric absorption layer (e.g., a III-V material and a germanium material) can be integrated on the same substrate to achieve heterogeneous integration of the lithium niobate modulator and the photodetector.

[0069] Before introducing the optical transceiver and its manufacturing method provided by the embodiments of the present disclosure, we first define the various directions that may be involved in the embodiments of the present disclosure. The direction perpendicular to the substrate is defined as the Z direction. The X direction and the Y direction are defined in a plane perpendicular to the Z direction. The X direction and the Y direction may intersect. In a specific embodiment, the X direction and the Y direction may be perpendicular to each other. In this case, the X direction, the Y direction, and the Z direction are mutually perpendicular. Here, the optical signal transmission direction is defined as the X direction, and the cross-section perpendicular to the optical signal transmission direction is the YZ plane.

[0070] 2A and 2B , FIG2A is a schematic structural diagram of an optical transceiver provided in an embodiment of the present disclosure, and FIG2B is a side view of the optical transceiver provided in an embodiment of the present disclosure.

[0071] As shown in Figures 2A and 2B, the optical transceiver 100 includes an optical modulation region 102, a first optical coupling region 106, and an optical detection region 110; wherein the first optical coupling region 106 is located between the optical modulation region 102 and the optical detection region 110. A modulator, such as a lithium niobate modulator 104, may be formed in the optical modulation region 102, a first optical coupling structure 108 may be formed in the first optical coupling region 106, and a photodetector 112 may be formed in the optical detection region 110. In other words, the lithium niobate modulator 104 in the optical modulation region 102 may be used to modulate an optical signal and output the modulated optical signal, the first optical coupling structure 108 in the first optical coupling region 106 may be used to couple the modulated optical signal to the optical detection region 110, and the photodetector 112 in the optical detection region 110 may be used to convert the modulated optical signal into an electrical signal.

[0072] In some embodiments, the optical transceiver 100 may further include a second optical coupling region 114. Along the optical signal transmission direction, the optical transceiver 100 sequentially includes a lithium niobate modulator 104, a first optical coupling structure 108, a photodetector 112, and a second optical coupling structure 116. Optical signals not coupled into the optical detection region 110 may be coupled into the second optical coupling structure 116 within the second optical coupling region 114 and output.

[0073] Referring to Figures 3A to 3H , which illustrate schematic cross-sectional views of a lithium niobate modulator during manufacturing according to embodiments of the present disclosure, Figures 3A to 3H illustrate the cross-sectional structure of the optical modulation region, with the cross-section perpendicular to the direction of optical signal transmission, i.e., the cross-section is along the YZ plane of the optical modulation region. The manufacturing process of the lithium niobate modulator according to embodiments of the present disclosure will be described in detail below, with reference to Figures 3A to 3H .

[0074] In the embodiment of the present disclosure, in step S101 , a substrate 118 is provided. The substrate 118 includes a substrate 120 , a buried oxide layer 122 , and a lithium niobate layer 124 stacked in sequence. The substrate 118 includes a light modulation region 102 and a light detection region 110 .

[0075] As shown in Figures 2A and 3A , substrate 118 includes a substrate 120, a buried oxide layer 122, and a lithium niobate layer 124 stacked in sequence. Substrate 118 includes a light modulation region 102, a first light coupling region 106, a light detection region 110, and a second light coupling region 114. Figure 3A only illustrates the cross-sectional structure of substrate 118 within light modulation region 102.

[0076] Here, the substrate can be, for example, lithium niobate on insulator, and includes, along the optical signal transmission direction (i.e., the X direction), a light modulation region, a light detection region, and a first light coupling region located between the light modulation region and the light detection region. Along the Z direction, the substrate includes a substrate, a buried oxide layer, and a lithium niobate layer stacked in sequence. The substrate can be, for example, made of silicon, the buried oxide layer is made of silicon dioxide, and the lithium niobate layer is a lithium niobate thin film.

[0077] In the embodiment of the present disclosure, in step S102 , the lithium niobate layer 124 located in the light modulation region 102 is etched to form a thin film lithium niobate waveguide 130 .

[0078] Here, etching the lithium niobate layer in the light modulation region along the Z direction can be divided into two cases depending on the etching depth. In some embodiments, the etching depth of the lithium niobate layer is less than the thickness of the lithium niobate layer. In other words, after etching the lithium niobate layer to form the thin-film lithium niobate waveguide, the buried oxide layer is not exposed. In other embodiments, the etching depth of the lithium niobate layer is the same as the thickness of the lithium niobate layer. In other words, after etching the lithium niobate layer to form the thin-film lithium niobate waveguide, the buried oxide layer is exposed.

[0079] In some embodiments, step S102 includes:

[0080] The lithium niobate layer 124 located in the light modulation region 102 is etched in a direction perpendicular to the substrate 120 (i.e., the Z direction) to form a thin film lithium niobate waveguide 130; wherein the etching depth of the lithium niobate layer 124 is less than the thickness of the lithium niobate layer 124;

[0081] After step S102, the manufacturing method further includes:

[0082] A plurality of first metal electrodes 136 are formed on the lithium niobate layer 124 .

[0083] As shown in FIG. 3A , a first photoresist layer 126 is formed covering the substrate 118 .

[0084] For example, the first photoresist layer can be formed by spin coating, wherein a first photoresist solution is applied to a substrate; the first photoresist solution is evenly distributed on the surface of the substrate due to the centrifugal force generated by the spin; and the first photoresist layer is formed by baking to volatilize the solvent in the first photoresist solution.

[0085] In a specific embodiment, the material of the first photoresist layer may be, for example, electron beam photoresist, such as hydrogen silsesquioxane polymers (HSQ). Of course, the embodiment of the present disclosure may also use other materials to form the first photoresist layer.

[0086] It should be noted that the first photoresist layer can cover the light modulation area, the first light coupling area, the light detection area and the second light coupling area of ​​the substrate. Figure 3A only shows that the first photoresist layer covers the substrate in the light modulation area.

[0087] 3A and 3B , after forming the first photoresist layer 126 covering the substrate 118 , the first photoresist layer 126 may be patterned using a mask layer (not shown in FIG. 3B ) to form a patterned first photoresist layer 128 .

[0088] For example, a mask layer may be formed on the first photoresist layer, and exposure processing may be performed after alignment to transfer the pattern of the mask layer to the first photoresist layer. After removing part of the first photoresist layer material, a patterned first photoresist layer may be formed.

[0089] 3B and 3C , the patterned first photoresist layer 128 is used to etch away a portion of the lithium niobate layer 124 along the Z direction to form a thin-film lithium niobate waveguide 130. At this point, the etching depth of the lithium niobate layer 124 is less than the thickness of the lithium niobate layer 124 . After the thin-film lithium niobate waveguide 130 is formed through etching, the buried oxide layer 122 is not exposed. The etching depth and the thickness of the lithium niobate layer 124 both refer to dimensions in the Z direction.

[0090] In some embodiments, the thin-film lithium niobate waveguide can be, for example, a ridge-type optical waveguide, which can include a 2×2 beam splitter, a Mach-Zehnder waveguide, and a 2×2 beam combiner. The Mach-Zehnder waveguide can include two optical waveguide arms. The output of the 2×2 beam splitter is connected to the input of the 2×2 beam combiner via a Mach-Zehnder waveguide. In other words, the 2×2 beam splitter and the 2×2 beam combiner are connected via two optical waveguide arms. In fact, the disclosed embodiments do not specifically limit the shape of the thin-film lithium niobate waveguide.

[0091] In some embodiments, the process of etching to form the thin-film lithium niobate waveguide may include, but is not limited to, dry etching. In fact, the embodiments of the present disclosure have no particular limitation on the process of etching to form the thin-film lithium niobate waveguide.

[0092] 3C and 3D , after etching to form the thin-film lithium niobate waveguide 130 , the patterned first photoresist layer 128 is removed to expose the thin-film lithium niobate waveguide 130 .

[0093] In some embodiments, the patterned first photoresist layer may be removed by dissolving with a solvent, or the patterned first photoresist layer may be removed by an etching process. The present disclosure does not specifically limit the process for removing the patterned first photoresist layer.

[0094] As shown in FIG. 3E , a second photoresist layer 132 is formed covering the thin film lithium niobate waveguide 130 .

[0095] For example, the second photoresist layer can be formed by spin coating, wherein a second photoresist solution is applied to the substrate; the second photoresist solution is evenly distributed on the surface of the substrate due to the centrifugal force generated by the spin; and the second photoresist layer is formed by baking to volatilize the solvent in the second photoresist solution.

[0096] In the embodiments of the present disclosure, there is no particular limitation on the material of the second photoresist layer. In some embodiments, the material of the first photoresist layer and the material of the second photoresist layer can be the same or different.

[0097] As shown in FIG3F , after forming a second photoresist layer 132 covering thin-film lithium niobate waveguide 130, a mask layer (not shown in FIG3F ) can be used to pattern the second photoresist layer 132 to form openings 134 exposing the lithium niobate layer. FIG3F illustrates that the openings 134 in the second photoresist layer can be located between adjacent ridge-type optical waveguides.

[0098] Similarly, a mask layer can be formed on the second photoresist layer, and exposure processing can be performed after alignment to transfer the pattern of the mask layer to the second photoresist layer. After removing part of the second photoresist layer material, a patterned second photoresist layer is formed.

[0099] As shown in FIG3G , a conductive material is deposited within the opening 134 of the second photoresist layer to form a first metal electrode 136. The first metal electrode 136 is in contact with the lithium niobate layer 124. During the deposition of the conductive material within the opening 134 of the second photoresist layer, the conductive material also covers the second photoresist layer 132.

[0100] In some embodiments, the process of forming the first metal electrode may include but is not limited to chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma enhanced chemical vapor deposition (PECVD), sputtering process and electroplating process.

[0101] In some embodiments, the material of the first metal electrode may include, but is not limited to, gold (Au), indium (In), or gold-tin alloy (AuSn).

[0102] As shown in FIG. 3H , the conductive material covering the second photoresist layer 132 is removed, and the second photoresist layer 132 is removed to expose the surface of the thin film lithium niobate waveguide 130 .

[0103] In the disclosed embodiment, a lithium niobate modulator is formed in the optical modulation area, and the optical signal is transmitted to the thin-film lithium niobate waveguide. By applying a voltage to the first metal electrode, the refractive index of the thin-film lithium niobate waveguide is changed, so that the optical signals passing through the two waveguide arms of the Mach-Zehnder generate a phase difference. After passing through the 2×2 combiner, the amplitude of the output light changes due to interference, thereby achieving modulation of the optical signal.

[0104] Referring to Figures 4A to 4H, Figures 4A to 4H are schematic diagrams of the cross-sectional structure of the optical transceiver provided in the embodiment of the present disclosure during the manufacturing process. Figures 4A to 4D only illustrate the schematic diagram of the cross-sectional structure of the optical modulation area. In combination with Figure 2A, Figures 4A to 4D illustrate the schematic diagram of the cross-sectional structure of the optical modulation area perpendicular to the direction of optical signal transmission, that is, the cross section is the YZ plane of the optical modulation area. Figures 4E to 4H illustrate the schematic diagram of the cross-sectional structure of the optical modulation area and the optical detection area. In combination with Figure 2A, Figures 4E to 4H illustrate the schematic diagram of the cross-sectional structure of the optical modulation area and the optical detection area perpendicular to the direction of optical signal transmission, that is, the cross section is the YZ plane of the optical modulation area. The manufacturing process of the optical transceiver provided in the embodiment of the present disclosure will be described in detail below in combination with Figures 4A to 4H.

[0105] For ease of explanation, Figures 4E to 4H illustrate that the light detection region is located between adjacent light modulation regions. This does not represent the actual relative positional relationship between the light modulation region and the photodetector. The light modulation region illustrated in Figures 4E to 4H can be viewed as a schematic cross-sectional structure diagram along the AA direction in Figure 2A , and the light detection region illustrated in Figures 4E to 4H can be viewed as a schematic cross-sectional structure diagram along the BB direction in Figure 2A .

[0106] The process of forming a thin-film lithium niobate waveguide in the light modulation area will be described in detail below with reference to FIG. 4A to FIG. 4D .

[0107] As shown in Figures 2A and 4A , substrate 118 includes a substrate 120, a buried oxide layer 122, and a lithium niobate layer 124 stacked in sequence. Substrate 118 includes a light modulation region 102, a first light coupling region 106, a light detection region 110, and a second light coupling region 114. Figure 4A only illustrates the cross-sectional structure of substrate 118 within light modulation region 102.

[0108] In the embodiment of the present disclosure, step S102 includes:

[0109] The lithium niobate layer 124 in the light modulation region 102 is etched along a direction perpendicular to the substrate 120 (i.e., the Z direction) to form a thin-film lithium niobate waveguide 130 and expose the buried oxide layer 122. The depth of the lithium niobate layer 124 is equal to the thickness of the lithium niobate layer 124.

[0110] After step S102, the manufacturing method further includes:

[0111] A plurality of first metal electrodes 136 are formed on the buried oxide layer 122 .

[0112] As shown in FIG. 4A , a first photoresist layer 126 is formed covering the substrate 118 .

[0113] As shown in FIG. 4B , after forming a first photoresist layer 126 covering the substrate 118 , the first photoresist layer 126 may be patterned using a mask layer (not shown in FIG. 4B ) to form a patterned first photoresist layer 128 .

[0114] 4B and 4C , the lithium niobate layer 124 is partially etched away through the patterned first photoresist layer 128 along the Z direction to form a thin-film lithium niobate waveguide 130. At this point, the etching depth of the lithium niobate layer 124 is equal to the thickness of the lithium niobate layer 124. After the thin-film lithium niobate waveguide 130 is formed, the buried oxide layer 122 is exposed. The etching depth and the thickness of the lithium niobate layer 124 both refer to the dimensions in the Z direction.

[0115] 4C and 4D , after etching to form the thin-film lithium niobate waveguide 130 , the patterned first photoresist layer 128 is removed to expose the thin-film lithium niobate waveguide 130 .

[0116] In the lithium niobate modulator 104 illustrated in Figures 3A to 3H , the first metal electrode 136 is in contact with the lithium niobate layer 124. In the lithium niobate modulator 104 illustrated in Figures 4A to 4D , the first metal electrode 136 is subsequently formed to contact the buried oxide layer 122. The specific process of forming the first metal electrode 136 can be found in the description of Figures 3E to 3H , and will not be repeated here.

[0117] The process of forming the light absorption layer in the light detection area will be described in detail below with reference to FIG. 4E to FIG. 4H .

[0118] In the embodiment of the present disclosure, in step S103 , the lithium niobate layer 124 and a portion of the buried oxide layer 122 located in the light detection region 110 are removed to form a groove 142 ; the bottom of the groove 142 exposes the substrate 120 .

[0119] In the embodiment of the present disclosure, step S103 includes:

[0120] The lithium niobate layer 124 located in the light detection region 110 is removed to expose the buried oxide layer 122;

[0121] The buried oxide layer 122 in the photo detection region 110 is etched along a direction perpendicular to the substrate 120 (ie, the Z direction) to form a groove 142 . The depth of the groove 142 is the same as the thickness of the buried oxide layer 122 .

[0122] 2B and 4E , the lithium niobate layer 124 in the light detection region 110 can be removed to expose the surface of the buried oxide layer 122. A third photoresist layer 138 is then formed covering the buried oxide layer 122 in the light detection region 110. Here, the third photoresist layer 138 covers both the buried oxide layer 122 in the light detection region 110 and the thin-film lithium niobate waveguide 130 in the light modulation region 102.

[0123] Illustratively, forming the third photoresist layer may be achieved by a spin coating method.

[0124] In the embodiment of the present disclosure, there is no particular limitation on the material of the third photoresist layer. In some embodiments, the materials of the first photoresist layer, the second photoresist layer, and the third photoresist layer can be the same or different.

[0125] 4E and 4F , after forming a third photoresist layer 138 covering the thin-film lithium niobate waveguide 130, the third photoresist layer 138 can be patterned using a mask layer (not shown in FIG. 4F ) to form openings 140 exposing the buried oxide layer 122. FIG. 4F illustrates that the openings 140 in the third photoresist layer expose the buried oxide layer 122 located in the light detection region 110.

[0126] Similarly, a mask layer can be formed on the third photoresist layer, and exposure processing can be performed after alignment to transfer the pattern of the mask layer to the third photoresist layer. After removing part of the third photoresist layer material, a patterned third photoresist layer is formed.

[0127] As shown in FIG4G , the buried oxide layer 122 in the light detection region 110 is etched along the Z direction to form a groove 142. The depth of the groove 142 is equal to the thickness of the buried oxide layer 122. The etching depth of the buried oxide layer 122 is equal to the thickness of the buried oxide layer 122, that is, the etching penetrates the buried oxide layer 122. In other words, the bottom of the groove 142 formed by the etching exposes the surface of the substrate 120.

[0128] In some embodiments, the buried oxide layer in the photodetection region may be etched using a combination of dry etching and wet etching.

[0129] In the embodiment of the present disclosure, in step S104, a light absorbing layer 144 is formed in the groove 142; wherein the thin film lithium niobate waveguide 130 is used to modulate the optical signal and output the modulated optical signal; the light absorbing layer 144 is used to detect the modulated optical signal and convert the modulated optical signal into an electrical signal.

[0130] As shown in FIG. 4H , a light absorbing layer 144 may be formed in the groove 142 , and the light absorbing layer 144 is in contact with the buried oxide layer 122 .

[0131] In some embodiments, the process of forming the light absorbing layer may include, but is not limited to, CVD.

[0132] It should be noted that the bottom of the thin-film lithium niobate waveguide in the optical modulation region contacts the buried oxide layer, while the bottom of the light absorption layer in the optical detection region contacts the substrate. In other words, the bottom of the thin-film lithium niobate waveguide in the optical modulation region and the bottom of the light absorption layer in the optical detection region are at different heights along the Z direction. To illustrate the height difference between the bottom of the thin-film lithium niobate waveguide in the optical modulation region and the bottom of the light absorption layer in the optical detection region, Figures 4E through 4H simultaneously illustrate the cross-sectional structures of the optical modulation region 102 and the optical detection region 110.

[0133] In the embodiment of the present disclosure, the material of the light absorbing layer 144 includes germanium or Group III-V materials.

[0134] It should be noted that the lithium niobate crystal used in the modulator belongs to the trigonal system, with lattice constants of 0.5147nm and 1.3856nm, respectively. In contrast, the lattice constant of Group III-V materials used in the light absorption layer of photodetectors, such as gallium arsenide, is 0.565nm, and the lattice constant of germanium used in the light absorption layer of photodetectors is 0.5657nm. Therefore, the lattice mismatch between the lithium niobate crystal used in the modulator and the Group III-V materials and germanium used in photodetectors is greater than 9%. This means that it is difficult to obtain high-quality gallium arsenide and germanium single crystals by epitaxial growth directly on lithium niobate crystals. Consequently, the resulting optical transceiver faces challenges in reliability and manufacturability.

[0135] In the disclosed embodiment, the lithium niobate layer located in the light modulation area is etched to form a thin film lithium niobate waveguide, and the lithium niobate layer and the buried oxide layer located in the light detection area are etched away to form a groove exposing the substrate, and then a light absorption layer is formed in the groove. The lattice mismatch between the substrate (e.g., silicon) and the light absorption layer (e.g., III-V material and germanium) is small, and the deposition of high-quality III-V material or germanium material can be achieved on the substrate, so that the lithium niobate modulator and the photodetector can be integrated on the same substrate.

[0136] 5 and 6 , FIG5 is a schematic diagram of the three-dimensional structure of the photodetector provided in an embodiment of the present disclosure, and FIG6 is a schematic diagram of the cross-sectional structure of the photodetector and lithium niobate modulation provided in an embodiment of the present disclosure.

[0137] For ease of explanation, Figure 6 illustrates a schematic cross-sectional structure of both the optical modulation region 102 and the optical detection region 110 perpendicular to the direction of optical signal transmission. This does not represent the actual relative positional relationship between the optical modulation region 102 and the photodetector. Specifically, the optical modulation region 102 illustrated in Figure 6 can be viewed as a schematic cross-sectional structure along the AA direction in Figure 2A , and the optical detection region 110 illustrated in Figure 6 can be viewed as a schematic cross-sectional structure along the BB direction in Figure 2A .

[0138] 5 and 6 , in the embodiment of the present disclosure, after step S103, the manufacturing method further includes:

[0139] Doping the substrate 120 on two opposite sides of the bottom of the groove perpendicular to the optical signal transmission direction (ie, the Y direction) to form a first doping region 146 and a second doping region 148 respectively;

[0140] After step S104, the manufacturing method further includes:

[0141] The buried oxide layer 122 located in the light detection region 110 is removed to expose the surfaces of the first doping region 146 and the second doping region 148 ;

[0142] A second metal electrode 150 and a third metal electrode 152 are formed on the first doping region 146 and the second doping region 148 , respectively.

[0143] In some embodiments, the first doping region 146 may be an N-type doping region, and the second doping region 148 may be a P-type doping region. In other embodiments, the first doping region 146 may be a P-type doping region, and the second doping region 148 may be an N-type doping region.

[0144] Illustratively, after forming the light absorbing layer 144, the buried oxide layer 122 located in the light detection region 110 is removed to expose the surfaces of the first doping region 146 and the second doping region 148, and at the same time expose the sidewalls of the light absorbing layer 144 on both sides opposite to each other along the Y direction; a dielectric layer may also be formed to cover the substrate 120 (including the first doping region 146 and the second doping region 148) located in the light detection region 110 and the sidewalls of the light absorbing layer 144; etching is performed to form a first through hole and a second through hole penetrating the dielectric layer and respectively exposing the first doping region 146 and the second doping region 148; and conductive material is deposited in the first through hole and the second through hole to form a second metal electrode 150 and a third metal electrode 152, respectively.

[0145] In the embodiment of the present disclosure, the materials of the second metal electrode and the third metal electrode may include but are not limited to gold (Au), platinum (Pt), titanium (Ti), etc.

[0146] FIG6 also shows the thin-film lithium niobate waveguide 130 located in the optical modulation region 102. The bottom of the thin-film lithium niobate waveguide 130 contacts the buried oxide layer 122, while the bottom of the light absorption layer 144 located in the optical detection region 110 contacts the substrate 120. In other words, the bottom of the thin-film lithium niobate waveguide 130 in the optical modulation region 102 and the bottom of the light absorption layer 144 in the optical detection region 110 have different heights along the Z direction. More specifically, the height difference along the Z direction between the bottom of the thin-film lithium niobate waveguide 130 in the optical modulation region 102 and the bottom of the light absorption layer 144 in the optical detection region 110 is the same as the thickness of the buried oxide layer 122. To facilitate illustration of the height difference between the bottom of the thin-film lithium niobate waveguide 130 in the optical modulation region 102 and the bottom of the light absorption layer 144 in the optical detection region 110, FIG6 also illustrates a schematic cross-sectional structure of the optical modulation region 102 and the optical detection region 110.

[0147] Referring to Figure 7 , which illustrates a cross-sectional view of an optical transceiver according to an embodiment of the present disclosure, Figure 7 also illustrates thin-film lithium niobate waveguide 130 located in optical modulation region 102 , first suspended waveguide 156 located in first optical coupling region 106 , and light absorption layer 144 located in optical detection region 110 . The cross-sectional view in Figure 7 is taken along the XZ plane.

[0148] As shown in conjunction with FIG. 2B and FIG. 7 , in the embodiment of the present disclosure, the substrate 118 further includes a first light coupling region 106 , and the first light coupling region 106 is located between the light modulation region 102 and the light detection region 110 ;

[0149] The lithium niobate layer 124 and a portion of the substrate 120 located in the first light coupling region 106 are removed to form a first air cavity 154 between the remaining substrate (i.e., the first silicon layer 158) and the buried oxide layer 122. The buried oxide layer 122 located in the first light coupling region 106 forms a first suspended waveguide 156. The first suspended waveguide 156 is used to couple the modulated optical signal to the light absorbing layer 144.

[0150] In some embodiments, the surface of the light absorbing layer 144 located in the light detection region 110 and the surface of the buried oxide layer 122 located in the first light coupling region 106 can be substantially flush. Substantially flush means that the thickness of the light absorbing layer 144 along the Z direction is the same as the thickness of the buried oxide layer 122 along the Z direction.

[0151] In other embodiments, the surface of the light absorbing layer 144 located in the light detection region 110 may be lower than the surface of the buried oxide layer 122 located in the first light coupling region 106. In a subsequent process, a dielectric layer 166 may be formed on the surface of the light absorbing layer 144. The sum of the thicknesses of the light absorbing layer 144 and the dielectric layer 166 along the Z direction is equal to the thickness of the buried oxide layer 122 along the Z direction. The material of the dielectric layer 166 may be the same as that of the buried oxide layer 122.

[0152] In the disclosed embodiment, the thin-film lithium niobate waveguide 130 located in the optical modulation region 102 contacts the buried oxide layer 122, while the light absorption layer 144 located in the optical detection region 110 contacts the substrate 120. However, due to the difference in Z-direction height between the bottoms of the thin-film lithium niobate waveguide 130 and the light absorption layer 144, the thin-film lithium niobate waveguide 130 in the lithium niobate modulator 104 cannot directly couple the modulated optical signal to the light absorption layer 144 in the photodetector 112. Therefore, a first optical coupling region 106 is provided between the lithium niobate modulator 104 and the photodetector 112, and the buried oxide layer 122 within the first optical coupling region 106 is fabricated into a first suspended waveguide 156. The modulated optical signal is then coupled to the light absorption layer 144 via the first suspended waveguide 156.

[0153] Here, the refractive index of the substrate 120 (e.g., silicon) is greater than that of the buried oxide layer 122 (e.g., silicon dioxide), and the refractive index of the buried oxide layer 122 is greater than that of air. The buried oxide layer has two surfaces disposed opposite each other along the Z direction. A first air cavity 154 is formed on one surface of the buried oxide layer 122, while the other surface of the buried oxide layer 122 is directly in contact with air, using air as a cladding layer to better prevent leakage of the modulated optical signal.

[0154] For example, a portion of the buried oxide layer located in the first optical coupling region can be etched to form a through hole exposing the substrate. The through hole etching is then used to remove a portion of the substrate to form a first air cavity between the remaining substrate and the buried oxide layer. In fact, the disclosed embodiments do not impose any particular limitations on the process for forming the first suspended waveguide.

[0155] 2A and 2B , the substrate further includes a second light coupling region 114, within which a second light coupling structure 116 may be formed. The process for forming the second light coupling structure 116 is similar to the process for forming the first light coupling structure 108. Specifically, the lithium niobate layer 124 and a portion of the substrate 120 located in the second light coupling region 114 are removed to form a second air cavity 160 between the remaining substrate (i.e., the second silicon layer 164) and the buried oxide layer 122. The buried oxide layer 122 located in the second light coupling region 114 forms a second suspended waveguide 162.

[0156] In the disclosed embodiment, the optical transceiver includes an optical modulator, a first optical coupling structure, and a photodetector, sequentially arranged along the optical signal transmission direction (i.e., the X direction). The optical transceiver includes the following three operating modes: In the first operating mode, an optical signal is input into the modulator (i.e., a lithium niobate modulator), modulated by the modulator, and then output as a modulated optical signal; in the second operating mode, an optical signal is input into the photodetector, where it is converted into an electrical signal for output; and in the third operating mode, an optical signal is input into the modulator, modulated by the modulator, and then output as a modulated optical signal to the first optical coupling structure. A first suspended waveguide in the first optical coupling structure couples the modulated optical signal to the photodetector, where it is converted into an electrical signal for output.

[0157] The embodiment of the present disclosure also provides an optical transceiver.

[0158] 2A and 2B , in an embodiment of the present disclosure, the optical transceiver 100 includes: a lithium niobate modulator 104 (as shown in the dashed box in FIG. 2A ), a first optical coupling structure 108, and a photodetector 112 (as shown in the dotted box in FIG. 2A ) located on a substrate 118, wherein the first optical coupling structure 108 is located between the lithium niobate modulator 104 and the photodetector 112; the substrate 118 includes a substrate 120, a buried oxide layer 122, and a lithium niobate layer 124 stacked in sequence (as shown in FIG. 3A ); wherein the lithium niobate modulator 104, the first optical coupling structure 108, and the photodetector 112 are respectively located in the optical modulation region 102, the first optical coupling region 106, and the optical detection region 110.

[0159] The lithium niobate modulator 104 includes a substrate 120, a buried oxide layer 122 located on the substrate 120, and a thin-film lithium niobate waveguide 130 located on the buried oxide layer 122. The thin-film lithium niobate waveguide 130 is formed by etching the lithium niobate layer 124.

[0160] The first light coupling structure 108 includes a first silicon layer 158, a first suspended waveguide 156, and a first air cavity 154 located between the first silicon layer 158 and the first suspended waveguide 156. The first silicon layer 158 is formed by etching a portion of the substrate 120 located in the first light coupling region 106. The first suspended waveguide 156 is formed by the buried oxide layer 122 located in the first light coupling region 106.

[0161] The photodetector 112 includes: a substrate 120 and a light absorbing layer 144 located on the substrate 120; wherein the thin film lithium niobate waveguide 130 is used to modulate the optical signal and output the modulated optical signal; the first suspended waveguide 156 is used to couple the modulated optical signal to the light absorbing layer 144; the light absorbing layer 144 is used to detect the modulated optical signal and convert the modulated optical signal into an electrical signal.

[0162] 2A does not illustrate the buried oxide layers in the first and second light coupling regions to facilitate illustration of the remaining substrate 120 (i.e., the first silicon layer 158 and the second silicon layer 164) in the first and second light coupling regions. In practice, a first air cavity 154 is formed between the remaining substrate 120 (i.e., the first silicon layer 158) and the buried oxide layer 122 in the first light coupling region 106, and the buried oxide layer 122 can function as a first suspended waveguide 156. A second air cavity 160 is formed between the remaining substrate 120 (i.e., the second silicon layer 164) and the buried oxide layer 122 in the second light coupling region 114, and the buried oxide layer 122 can function as a second suspended waveguide 162.

[0163] As shown in FIG3H , in the embodiment of the present disclosure, the lithium niobate modulator 104 further includes:

[0164] The first metal electrode 136 contacts the thin film lithium niobate waveguide 130 .

[0165] As shown in FIG. 2A , the lithium niobate modulator 104 further includes a first metal electrode 136 , which is in contact with the buried oxide layer 122 .

[0166] As shown in FIG6 , in the embodiment of the present disclosure, the photodetector 112 further includes:

[0167] A first doping region 146 and a second doping region 148 are formed by doping the substrate 120 ; the light absorbing layer 144 is located between the first doping region 146 and the second doping region 148 ;

[0168] The second metal electrode 150 and the third metal electrode 152 are respectively located on the first doping region 146 and the second doping region 148 .

[0169] As shown in Figures 2A and 2B, the optical transceiver 100 further includes a second optical coupling structure 116. The second optical coupling structure 116 includes a second silicon layer 164, a second suspended waveguide 162, and a second air cavity 160 located between the second silicon layer 164 and the second suspended waveguide 162. The second silicon layer 164 is formed by etching a portion of the substrate 120 located in the second optical coupling region 114. The second suspended waveguide 162 is formed by the buried oxide layer 122 located in the second optical coupling region 114.

[0170] The present disclosure provides an optical transceiver and a method for manufacturing the same. The method comprises: providing a substrate, the substrate comprising a substrate, a buried oxide layer, and a lithium niobate layer stacked in sequence; the substrate comprising an optical modulation region and an optical detection region; etching the lithium niobate layer in the optical modulation region to form a thin-film lithium niobate waveguide; removing the lithium niobate layer and a portion of the buried oxide layer in the optical detection region to form a groove; exposing the substrate at the bottom of the groove; and forming a light absorption layer in the groove; wherein the thin-film lithium niobate waveguide is used to modulate an optical signal and output the modulated optical signal; and the light absorption layer is used to detect the modulated optical signal and convert the modulated optical signal into an electrical signal. In the embodiment of the present disclosure, the base includes a substrate, a buried oxide layer and a lithium niobate layer stacked in sequence. The lithium niobate layer located in the light modulation area is etched to form a thin film lithium niobate waveguide, and the lithium niobate layer and the buried oxide layer located in the light detection area are etched away to form a groove exposing the substrate, and then a light absorption layer is formed in the groove, so that the lithium niobate modulator and the photodetector can be integrated on the same substrate, and the thin film lithium niobate waveguide is used to modulate the light signal and output the modulated light signal to the light absorption layer. The light absorption layer detects the modulated light signal and converts the modulated light signal into an electrical signal.

[0171] It should be understood that “one embodiment” or “an embodiment” mentioned throughout the specification means that specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present disclosure. Therefore, “in one embodiment” or “in an embodiment” appearing throughout the specification does not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner. It should be understood that in the various embodiments of the present disclosure, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present disclosure. The serial numbers of the embodiments of the present disclosure are for description only and do not represent the advantages and disadvantages of the embodiments.

[0172] The above description is only a preferred embodiment of the present disclosure and does not limit the patent scope of the present disclosure. All equivalent structural transformations made by using the contents of the present disclosure and the drawings under the inventive concept of the present disclosure, or direct / indirect application in other related technical fields are included in the patent protection scope of the present disclosure.

Claims

1. A method for manufacturing an optical transceiver, the method comprising: Providing a substrate, the substrate comprising a substrate, a buried oxide layer and a lithium niobate layer stacked in sequence; The substrate includes a light modulation region and a light detection region; Etching the lithium niobate layer located in the light modulation region to form a thin film lithium niobate waveguide; The lithium niobate layer and a portion of the buried oxide layer located in the light detection region are removed to form a groove; the bottom of the groove exposes the substrate; A light absorbing layer is formed in the groove; wherein the thin film lithium niobate waveguide is used to modulate the optical signal and output the modulated optical signal; the light absorbing layer is used to detect the modulated optical signal and convert the modulated optical signal into an electrical signal.

2. The method for manufacturing an optical transceiver according to claim 1, wherein: The etching of the lithium niobate layer in the light modulation region to form a thin film lithium niobate waveguide comprises: Etching the lithium niobate layer located in the light modulation area in a direction perpendicular to the substrate to form a thin film lithium niobate waveguide; wherein the etching depth of the lithium niobate layer is less than the thickness of the lithium niobate layer; After etching the lithium niobate layer located in the light modulation region to form a thin film lithium niobate waveguide, the manufacturing method further comprises: A plurality of first metal electrodes are formed on the lithium niobate layer.

3. The method for manufacturing an optical transceiver according to claim 1, wherein: The etching of the lithium niobate layer in the light modulation region to form a thin film lithium niobate waveguide comprises: Etching the lithium niobate layer located in the light modulation area in a direction perpendicular to the substrate to form a thin-film lithium niobate waveguide and expose the buried oxide layer; wherein the etching depth of the lithium niobate layer is the same as the thickness of the lithium niobate layer; After etching the lithium niobate layer located in the light modulation region to form a thin film lithium niobate waveguide, the manufacturing method further comprises: A plurality of first metal electrodes are formed on the buried oxide layer.

4. The method for manufacturing an optical transceiver according to claim 1, wherein: The substrate further comprises a light coupling region, wherein the light coupling region is located between the light modulation region and the light detection region; The lithium niobate layer and a portion of the substrate located in the optical coupling region are removed to form an air cavity between the remaining substrate and the buried oxide layer; wherein the buried oxide layer located in the optical coupling region forms a suspended waveguide; and the suspended waveguide is used to couple the modulated optical signal to the optical absorption layer.

5. The method for manufacturing an optical transceiver according to claim 4, wherein: The step of removing the lithium niobate layer and a portion of the buried oxide layer located in the light detection region to form a groove comprises: removing the lithium niobate layer located in the light detection region to expose the buried oxide layer; The buried oxide layer located in the light detection region is etched along a direction perpendicular to the substrate to form a groove; wherein the depth of the groove is the same as the thickness of the buried oxide layer.

6. The method for manufacturing an optical transceiver according to claim 5, wherein: After removing the lithium niobate layer and a portion of the buried oxide layer located in the light detection region to form a groove, the manufacturing method further includes: Doping the substrate at two opposite sides of the bottom of the groove perpendicular to the optical signal transmission direction to form a first doping region and a second doping region respectively; After forming the light absorbing layer in the groove, the manufacturing method further comprises: Removing the buried oxide layer located in the light detection region to expose the surfaces of the first doped region and the second doped region; A second metal electrode and a third metal electrode are formed on the first doping region and the second doping region, respectively.

7. The method for manufacturing an optical transceiver according to claim 1, wherein: The material of the substrate includes silicon; The material of the light absorbing layer includes germanium or Group III-V materials.

8. An optical transceiver, comprising: A lithium niobate modulator, an optical coupling structure and a photodetector are located on a substrate, wherein the optical coupling structure is located between the lithium niobate modulator and the photodetector; The base comprises a substrate, a buried oxide layer and a lithium niobate layer stacked in sequence; The lithium niobate modulator comprises: the substrate, a buried oxide layer located on the substrate, and a thin-film lithium niobate waveguide located on the buried oxide layer; the thin-film lithium niobate waveguide is formed by etching the lithium niobate layer; The optical coupling structure comprises: a silicon layer, a suspended waveguide and an air cavity located between the silicon layer and the suspended waveguide; the silicon layer is formed by etching a portion of the substrate; the suspended waveguide is formed by the buried oxide layer; The photodetector includes: the substrate and a light absorbing layer located on the substrate; wherein the thin film lithium niobate waveguide is used to modulate the optical signal and output the modulated optical signal; the suspended waveguide is used to couple the modulated optical signal to the light absorbing layer; the light absorbing layer is used to detect the modulated optical signal and convert the modulated optical signal into an electrical signal.

9. The optical transceiver according to claim 8, wherein: The lithium niobate modulator further comprises: A first metal electrode, wherein the first metal electrode is in contact with the thin-film lithium niobate waveguide or the first metal electrode is in contact with the buried oxide layer.

10. The optical transceiver according to claim 8, wherein: The photodetector further comprises: a first doping region and a second doping region, wherein the first doping region and the second doping region are formed by doping the substrate; and the light absorbing layer is located between the first doping region and the second doping region; A second metal electrode and a third metal electrode, wherein the second metal electrode and the third metal electrode are respectively located on the first doping region and the second doping region.

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