An electro-optic modulator, an optical module, and an optical transmission device.

Abstract

This invention discloses an electro-optic modulator, an optical module, and an optical transmission device, which, while maintaining a high modulation bandwidth, can reduce optical loss and improve modulation efficiency during optical signal modulation. The electro-optic modulator shown in this invention includes a first electrode and a second electrode located on the surface of a substrate. The electro-optic modulator also includes a transmission optical waveguide. The electric field between the first electrode and the second electrode is used to modulate the optical signal transmitted by the transmission optical waveguide. The first electrode includes a first conductive layer and a second conductive layer, with the second conductive layer located between the substrate and the first conductive layer. The conductivity of the first conductive layer is greater than that of the second conductive layer, and the light absorption coefficient of the first conductive layer is greater than that of the second conductive layer.

Description

Technical Field

[0001] This application relates to the field of optical communication technology, and in particular to an electro-optic modulator, an optical module, and an optical transmission device. Background Technology

[0002] Optical communication technology is a crucial carrier technology in the current internet world and one of the core technologies of the information age. Within optical communication technology, electro-optic modulators are key components in optical interconnects, optical computing, and optical communication systems.

[0003] Existing electro-optic modulators include a substrate, signal electrodes and ground electrodes located on the surface of the substrate, and a transmission optical waveguide located between adjacent signal electrodes and ground electrodes. The electrical signal transmitted by the signal electrodes generates an electric field between the signal electrodes and the ground electrodes. Changes in this electric field can modulate the optical signal transmitted by the transmission optical waveguide.

[0004] Taking the signal electrode as an example, the signal electrode is made of metal. Due to the absorption of optical signals by the metal, the closer the signal electrode is to the transmission optical waveguide, the greater the optical loss. To reduce optical loss, the distance between the signal electrode and the transmission optical waveguide needs to be increased. However, the greater the distance between the signal electrode and the transmission optical waveguide, the lower the modulation efficiency. Summary of the Invention

[0005] This invention provides an electro-optic modulator, an optical module, and an optical transmission device that can reduce optical loss and improve modulation efficiency while maintaining high modulation bandwidth.

[0006] A first aspect of this invention provides an electro-optic modulator. The electro-optic modulator includes a first electrode and a second electrode located on the surface of a substrate, and a transmission optical waveguide. The electric field between the first electrode and the second electrode is used to modulate an optical signal transmitted through the transmission optical waveguide. The first electrode includes a first conductive layer and a second conductive layer, the second conductive layer being located between the substrate and the first conductive layer. The conductivity of the first conductive layer is greater than the conductivity of the second conductive layer. The light absorption coefficient of the first conductive layer is greater than the light absorption coefficient of the second conductive layer. The first electrode can be a signal electrode or a ground electrode.

[0007] The light absorption coefficient of the first conductive layer is greater than that of the second conductive layer. Therefore, the second conductive layer introduces less optical loss, allowing the distance between the first electrode and the transmission waveguide to be reduced. Because the first electrode can be closer to the transmission waveguide, the electric field acts more strongly on it, effectively improving modulation efficiency. Furthermore, the conductivity of the first conductive layer is greater than that of the second conductive layer. The higher conductivity of the first conductive layer reduces microwave loss, thereby increasing the modulation bandwidth. It is evident that the higher conductivity of the first conductive layer can compensate for the microwave loss caused by the lower conductivity of the second conductive layer. By reducing the distance between the first electrode and the transmission waveguide, the size of the electro-optic modulator can be effectively reduced, improving its integration density.

[0008] Based on the first aspect, in one optional implementation, the second electrode includes a third conductive layer and a fourth conductive layer. The fourth conductive layer is located between the substrate and the third conductive layer. The conductivity of the third conductive layer is greater than the conductivity of the fourth conductive layer. The light absorption coefficient of the third conductive layer is greater than the light absorption coefficient of the fourth conductive layer. In one case, the first electrode is a signal electrode and the second electrode is a ground electrode. In another case, the first electrode is a ground electrode and the second electrode is a signal electrode.

[0009] As can be seen, both the first and second electrodes shown in this embodiment can result in lower optical loss and more effectively improve modulation efficiency. Furthermore, they effectively reduce the size of the electro-optic modulator and improve its integration density.

[0010] Based on the first aspect, in one optional implementation, the first conductive layer has a plurality of first upper protrusions protruding from the side of the third conductive layer. A first upper recess is formed between any two adjacent first upper protrusions. The third conductive layer has a plurality of second upper protrusions protruding from the side of the first conductive layer. A second upper recess is formed between any two adjacent second upper protrusions. Each first upper protrusion is positioned opposite a second upper recess, and each second upper protrusion is positioned opposite a first upper recess.

[0011] As can be seen, because the positions of the first upper layer protrusion and the second upper layer protrusion are staggered, the spacing between the first conductive layer and the third conductive layer can be effectively increased. This effectively reduces the parasitic capacitance between the first electrode and the second electrode.

[0012] Based on the first aspect, in one optional implementation, the second conductive layer protrudes a plurality of first lower layer protrusions towards the side of the fourth conductive layer. A first lower layer recess is formed between any two adjacent first lower layer protrusions. The fourth conductive layer protrudes a plurality of second lower layer protrusions towards the side of the second conductive layer. A second lower layer recess is formed between any two adjacent second lower layer protrusions. Each first lower layer protrusion is positioned opposite a second lower layer recess, and each second lower layer protrusion is positioned opposite a first lower layer recess.

[0013] As can be seen, because the positions of the first and second lower layer protrusions are staggered, the spacing between the third and fourth conductive layers can be effectively increased. This effectively reduces the parasitic capacitance between the first and second electrodes.

[0014] Based on the first aspect, in one optional implementation, each of the first upper protrusions included in the first conductive layer and one of the first lower protrusions included in the second conductive layer have overlapping projection positions on the substrate.

[0015] As can be seen, the projection positions of the first upper protrusion and the first lower protrusion on the substrate coincide, which effectively reduces the parasitic capacitance between the first electrode and the second electrode, and also reduces the difficulty of manufacturing an electro-optic modulator.

[0016] Based on the first aspect, in one optional implementation, each of the second upper protrusions included in the third conductive layer and a second lower protrusion included in the fourth conductive layer have overlapping projection positions on the substrate.

[0017] As can be seen, the projection positions of the second upper protrusion and the second lower protrusion on the substrate coincide, which effectively reduces the parasitic capacitance between the first electrode and the second electrode and also reduces the difficulty of manufacturing an electro-optic modulator.

[0018] Based on the first aspect, in one optional implementation, the first electrode includes a plurality of upper structure cycles. Each upper structure cycle includes at least one first upper protrusion and at least one first upper recess located adjacent to each other. Different upper structure cycles have the same structure. Along the extension direction of the first electrode, the number of upper structure cycles included by the first electrode per unit length is positively correlated with the modulation bandwidth of the electro-optic modulator.

[0019] It is evident that the more upper-layer structure periods within a given unit length, the more continuous the structure of the first electrode of the electro-optic modulator. This results in lower microwave loss from the first electrode, and consequently, a larger modulation bandwidth for the electro-optic modulator. Conversely, the fewer upper-layer structure periods within a given unit length, the more loosely structured the first electrode of the electro-optic modulator. This results in higher microwave loss from the first electrode, and consequently, a smaller modulation bandwidth for the electro-optic modulator.

[0020] Based on the first aspect, in one optional implementation, the first electrode includes a plurality of lower structure periods. Each lower structure period includes at least one first lower protrusion and at least one first lower recess located adjacent to each other. Different lower structure periods have the same structure. Along the extension direction of the first electrode, the number of lower structure periods included by the first electrode per unit length is positively correlated with the modulation bandwidth of the electro-optic modulator.

[0021] It is evident that the more lower-level structure periods within a given unit length, the more continuous the structure of the second electrode of the electro-optic modulator. This results in lower microwave loss from the second electrode, and consequently, a larger modulation bandwidth for the electro-optic modulator. Conversely, the fewer lower-level structure periods within a given unit length, the more loosely structured the second electrode of the electro-optic modulator. This results in higher microwave loss from the second electrode, and consequently, a smaller modulation bandwidth for the electro-optic modulator.

[0022] Based on the first aspect, in an optional implementation, the electro-optic modulator further includes an electric field confinement layer. The electric field confinement layer is located between the transmission optical waveguide and the first electrode. Alternatively, the electric field confinement layer is located between the transmission optical waveguide and the second electrode. Alternatively, the electric field confinement layer is located between the transmission optical waveguide and the first electrode, and also between the transmission optical waveguide and the second electrode. The electric field confinement layer is used to distribute the electric field on the transmission optical waveguide.

[0023] As can be seen, the electric field confinement layer ensures that the electric field between the first and second electrodes is primarily distributed along the transmission optical waveguide, thereby enhancing the interaction between the electric field and the optical field of the transmitted optical signal, thus improving modulation efficiency. Furthermore, because the electric field confinement layer is made of an insulating material, it is non-conductive and does not introduce microwave loss. Therefore, including the electric field confinement layer in an electro-optic modulator does not reduce the modulation bandwidth.

[0024] Based on the first aspect, in one optional implementation, the transmission optical waveguide is located on the surface of the substrate. The electric field confinement layer has a first side and a second side located opposite each other. The first side is adjacent to the location of the first electrode. Alternatively, the first side is adjacent to the location of the second electrode. The second side is adjacent to the location of the transmission optical waveguide.

[0025] Based on the first aspect, in an optional implementation, the electric field confinement layer extends to at least one of the following locations: a first upper protrusion included in the first electrode, a first upper recess included in the first electrode, a first lower protrusion included in the first electrode, a first lower recess included in the first electrode, a second upper protrusion included in the second electrode, a second upper recess included in the second electrode, a second lower protrusion included in the second electrode, or a second lower recess included in the second electrode.

[0026] Based on the first aspect, in an optional implementation, the transmission optical waveguide and the first electrode are located on opposite sides of the substrate, and / or, the transmission optical waveguide and the second electrode are located on opposite sides of the substrate. The substrate further includes an electric field confinement layer located between the transmission optical waveguide and the first electrode, and / or, the electric field confinement layer located between the transmission optical waveguide and the second electrode. The electric field confinement layer is used to ensure that the electric field is primarily distributed on the transmission optical waveguide.

[0027] Based on the first aspect, in one optional implementation, the electric field confinement layer is made of a high dielectric constant and insulating material. The refractive index of the material of the electric field confinement layer is less than the refractive index of the material of the transmission optical waveguide.

[0028] As can be seen, since the refractive index of the electric field confinement layer is lower than that of the transmission optical waveguide, the electric field confinement layer can distribute the electric field on the transmission optical waveguide to improve modulation efficiency. Furthermore, because the electric field confinement layer is made of a high dielectric constant and insulating material, it does not introduce microwave loss.

[0029] Based on the first aspect, in one optional implementation, the side of the first conductive layer facing the substrate includes a first region and a second region. The first region is in contact with the second conductive layer. The second region is in contact with the substrate.

[0030] Based on the first aspect, in one optional implementation, the side of the third conductive layer facing the substrate includes a third region and a fourth region. The third region is in contact with the fourth conductive layer. The fourth region is in contact with the substrate.

[0031] A second aspect of this invention provides an optical module. The optical module includes a light source and an electro-optic modulator as described in any of the first aspects above. The light source is connected to the transmission optical waveguide. The light source is used to transmit optical signals to the transmission optical waveguide.

[0032] A third aspect of this invention provides an optical transmitting device. The optical transmitting device includes a processor and an optical module as described in the second aspect above. The processor is connected to a signal electrode. The signal electrode is either the first electrode or the second electrode. The processor is used to transmit an electrical signal to the signal electrode. The electrical signal is used to modulate an optical signal transmitted by the transmission optical waveguide. Attached Figure Description

[0033] Figure 1 This is a structural example diagram of an optical communication system provided in this application;

[0034] Figure 2a This is a structural example diagram of an optical transmitting device provided in an embodiment of this application;

[0035] Figure 2b This is a first cross-sectional structural example of the electro-optic modulator provided in the embodiments of this application;

[0036] Figure 2c This is a top view example of the electro-optic modulator provided in the embodiments of this application;

[0037] Figure 3a This is an example of a second cross-sectional structure of the electro-optic modulator provided in the embodiments of this application;

[0038] Figure 3b This is a top view example of the electro-optic modulator provided in the embodiments of this application;

[0039] Figure 4a This is an example diagram of an overall structure of the electro-optic modulator provided in an embodiment of this application;

[0040] Figure 4b This is a top view example of the third type of electro-optic modulator structure provided in the embodiments of this application;

[0041] Figure 5 This is a top view example of the fourth type of electro-optic modulator provided in the embodiments of this application;

[0042] Figure 6a This is an example of a third cross-sectional structure of the electro-optic modulator provided in the embodiments of this application;

[0043] Figure 6b This is a top view example of the fifth type of electro-optic modulator provided in the embodiments of this application;

[0044] Figure 7a This is a top view example of the sixth type of electro-optic modulator provided in the embodiments of this application;

[0045] Figure 7b This is a top view example of the seventh structure of the electro-optic modulator provided in the embodiments of this application;

[0046] Figure 8 This is an example of a fourth cross-sectional structure of the electro-optic modulator provided in the embodiments of this application. Detailed Implementation

[0047] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] This application provides an electro-optic modulator that can improve modulation efficiency while reducing optical loss. For better understanding, the following is combined with... Figure 1 The structure of the optical communication system in which the electro-optic modulator provided in this application is applied is illustrated.

[0049] Figure 1 This is a structural example diagram of the optical communication system provided in this application. Figure 1 As shown, the optical communication system 100 includes an optical transmitting device 110 and an optical receiving device 120. This application does not limit the specific number of optical receiving devices 120 connected to the optical transmitting device 110. The optical transmitting device 110 shown in this application can also be referred to as a transmitter, transmitting end, or transmitting end device, etc. The optical receiving device 120 can also be referred to as a receiver, receiving end, or receiving end device, etc.

[0050] This application uses the application of an optical communication system 100 to an optical fiber access network, specifically in a passive optical network (PON), as an example. It can be seen that in the transmission direction of downlink optical signals, the optical transmitting device 110 is an optical line terminal (OLT), and the optical receiving device 120 is an optical network unit (ONU). In the transmission direction of uplink optical signals, the optical transmitting device 110 is an ONU, and the optical receiving device 120 is an OLT.

[0051] This application does not limit the specific type of network used in the optical communication system. For example, in other examples, it can also be applied to data center networks, wavelength division multiplexing networks, or optical transport networks (OTN). If applied to an OTN, both the optical transmitting device 110 and the optical receiving device 120 can be OTN devices.

[0052] Figure 2a This is a structural example diagram of an optical transmitting device provided in an embodiment of this application. Figure 2a As shown, the optical transmitting device 110 specifically includes an optical module 201 and a processor 202. The optical module 201 includes a light source 203 and an electro-optic modulator 210. The electro-optic modulator can be a Mach-Zehnder interferometer (MZI) or a micro-ring modulator.

[0053] Figure 2b This is a first cross-sectional structural example of the electro-optic modulator provided in the embodiments of this application. Figure 2c This is a top view example of a first type of electro-optic modulator provided in an embodiment of this application. Figure 2b For along Figure 2c The cross-sectional view obtained by cutting the electro-optic modulator with a transverse section of 200.

[0054] The electro-optic modulator shown in this embodiment includes a substrate. The substrate may include two layers: a substrate 211 at the bottom and an optical waveguide layer 212 located on the surface of the substrate 211. The substrate 211 may include silicon (Si), and may also include silicon dioxide (SiO2) deposited on the silicon surface. This embodiment does not limit the material of the substrate 211, as long as the substrate 211 has a stable structure and low optical absorption. For example, the substrate 211 may also be made of zirconium boride (ZrB2), gallium arsenide (GaAs), glass, magnesium oxide, etc. The optical waveguide layer 212 can form a transmission optical waveguide located between the signal electrode and the ground electrode. The optoelectronic material used to form the optical waveguide layer 212 shown in this embodiment may be lithium niobate (LiNbO3).

[0055] The electro-optic modulator shown in this embodiment includes a signal electrode 213 located on the surface of the optical waveguide layer 212, and a ground electrode 214 and a ground electrode 215 located on both sides of the signal electrode 213. The description of the number of signal electrodes and ground electrodes included in the electro-optic modulator 210 in this embodiment is an optional example and is not limited, as long as the electro-optic modulator 210 includes at least one signal electrode and at least one ground electrode.

[0056] The electro-optic modulator 210 also includes a transmission optical waveguide 216 and a transmission optical waveguide 217. The transmission optical waveguide 216 is located between the ground electrode 214 and the signal electrode 213. The transmission optical waveguide 217 is located between the signal electrode 213 and the ground electrode 215. The signal electrode 213 is connected to the processor 202. The ground electrodes 214 and 215 are grounded.

[0057] Taking the transmission optical waveguide 216 as an example, during the fabrication of the electro-optic modulator, the optical waveguide layer 212 can be etched to form the transmission optical waveguide 216. Specifically, the transmission optical waveguide 216 is formed by extending the optical waveguide layer 212 away from the substrate surface in a direction perpendicular to the substrate surface. It is understood that the transmission optical waveguide 216 protrudes from the surface of the optical waveguide layer 212.

[0058] Alternatively, in other examples, the substrate included in the electro-optic modulator may consist only of a substrate. A transmission optical waveguide is formed on the surface of the substrate and between the signal electrode and the ground electrode. The optoelectronic material of the transmission optical waveguide in this example may be one or more of the following: single-crystal silicon (Si), amorphous silicon (a-Si), silicon nitride (SiN) waveguide, aluminum nitride (AlN), titanium oxide (TiO2), or tantalum pentoxide (Ta2O3, etc.).

[0059] Light source 203 is connected to both transmission optical waveguide 216 and transmission optical waveguide 217. Light source 203 is used to transmit the optical signal to be modulated to transmission optical waveguide 216 and transmission optical waveguide 217, respectively. This embodiment does not limit the specific type of light source 203; for example, the light source 203 can be a laser, a light-emitting diode (LED), or a laser diode (LD), etc. Processor 202 is connected to signal electrode 213 and is used to send an electrical signal to signal electrode 213. This electrical signal is used to modulate the optical signals transmitted through transmission optical waveguide 216 and transmission optical waveguide 217. This embodiment does not limit the type of processor 202; for example, the processor 202 shown in this embodiment can be one or more chips or one or more integrated circuits. For example, processor 202 may be one or more field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), system-on-chips (SoCs), central processor units (CPUs), network processors (NPs), digital signal processors (DSPs), microcontroller units (MCUs), programmable logic devices (PLDs), or other integrated chips, or any combination of the above chips or processors.

[0060] The following is an exemplary description of the specific process by which the electro-optic modulator modulates an optical signal. When the signal electrode 213 receives an electrical signal from the processor 202, an electric field is generated between the signal electrode 213 and the ground electrode 214. The direction of this electric field is from the signal electrode 213 to the ground electrode 214; see [link to documentation] for details. Figure 2a The arrow shown points between signal electrode 213 and ground electrode 214. Similarly, an electric field is generated between signal electrode 213 and ground electrode 215. The direction of this electric field is from signal electrode 213 to ground electrode 215; see [reference needed] for details. Figure 2a The arrow shown points between the signal electrode 213 and the ground electrode 215.

[0061] Taking signal electrode 213 and ground electrode 214 as an example, the electric field between signal electrode 213 and ground electrode 214 is applied to the transmission optical waveguide 216 to modulate the optical signal transmitted within the transmission optical waveguide 216. Specifically, the optical signal to be modulated is transmitted along the transmission optical waveguide 216, and the transmission direction of the optical signal is perpendicular to the direction of the electric field between signal electrode 213 and ground electrode 214. The change in the electric field between signal electrode 213 and ground electrode 214 will change the effective refractive index of the transmission optical waveguide 216. The change in the effective refractive index of the transmission optical waveguide 216 will change the phase of the optical signal transmitted in the transmission optical waveguide 216, thereby achieving modulation of the optical signal transmitted in the transmission optical waveguide 216. For an explanation of the modulation process of the transmission optical waveguide 217, please refer to the diagram of the transmission optical waveguide 216, which will not be elaborated further here.

[0062] The distance between the signal electrode 213 and the ground electrode 214 is negatively correlated with the modulation efficiency of the optical signal transmitted through the transmission waveguide 216. It can be seen that the larger the distance between the signal electrode 213 and the ground electrode 214, the lower the modulation efficiency of the optical signal transmitted through the transmission waveguide 216. Similarly, the smaller the distance between the signal electrode 213 and the ground electrode 214, the higher the modulation efficiency of the optical signal transmitted through the transmission waveguide 216. For an explanation of the modulation efficiency of the optical signal transmitted through the transmission waveguide 307, please refer to the explanation of the modulation efficiency of the optical signal transmitted through the transmission waveguide 216; details will not be repeated here.

[0063] This embodiment provides a first electrode. The first electrode has a stacked structure, which ensures reduced optical loss even when the distance between the first electrode and the transmission optical waveguide 216 is reduced. The first electrode can be a signal electrode 213 or a ground electrode 214. It is understood that reducing the distance between the first electrode and the transmission optical waveguide 216 improves the modulation efficiency of the optical signal transmitted through the modulation transmission optical waveguide 216.

[0064] The structure of the first electrode, which is arranged in a stacked configuration, will be described below. For better understanding, the first electrode is illustrated as a signal electrode 213. In other examples, the first electrode may also be a ground electrode 214.

[0065] This embodiment, by reducing the distance between the signal electrode 213 and the transmission optical waveguide 216, can also effectively reduce the absorption of the optical signal transmitted by the signal electrode 213 on the transmission optical waveguide 216, thereby reducing the optical loss of the optical signal transmitted by the transmission optical waveguide 216. For this purpose, see... Figure 2bAs shown, the signal electrode 213 in this embodiment includes a first conductive layer 231 and a second conductive layer 232. The second conductive layer 232 is located between the substrate and the first conductive layer 231. The second conductive layer 232 is located on the side of the signal electrode 213 near the transmission optical waveguide 216.

[0066] The first conductive layer 231 is made of a metallic material. For example, the first conductive layer 231 may be made of at least one of the following metallic materials: gold (Au), silver (Ag), palladium (Pd), rhodium (Rh), iridium (Ir), osmium (Os), or ruthenium (Ru), etc.

[0067] The conditions that the second conductive layer 232 needs to meet are explained below. In this embodiment, the conductivity of the first conductive layer 231 is greater than that of the second conductive layer 232, and the light absorption coefficient of the first conductive layer 231 is greater than that of the second conductive layer 232. The second conductive layer 232 that meets these conditions can be made of a transparent conductive oxide (TCO). The TCO is mainly composed of oxides such as cadmium oxide (CdO), indium oxide (In₂O₃), tin dioxide (SnO₂), and zinc oxide (ZnO), as well as their corresponding composite compounds.

[0068] In this embodiment, the light absorption coefficient of the first conductive layer 231 is greater than that of the second conductive layer 232, and the second conductive layer 232 is closer to the transmission optical waveguide 216 than the first conductive layer 231. Therefore, the optical loss generated by the second conductive layer 232 is less than that generated by the first conductive layer 231, which is made of metal material alone. Moreover, because the conductivity of the first conductive layer 231 is greater than that of the second conductive layer 232, the microwave loss of the electrical signal during transmission through the first conductive layer 231 is reduced, and the modulation bandwidth is increased.

[0069] To better understand, a comparison will be made between the stacked signal electrode shown in this embodiment and the signal electrode made solely of metal materials shown in existing solutions.

[0070] Compared to signal electrodes in existing designs, the second conductive layer 232 of the signal electrode 213 shown in this embodiment has a smaller light absorption coefficient. Therefore, under the same optical loss conditions, such as 2 dB / cm, the second conductive layer 232 of this embodiment can be placed closer to the transmission optical waveguide 216. Thus, the signal electrode 213 of this embodiment can be placed closer to the transmission optical waveguide than the signal electrode in existing designs. Because the signal electrode 213 of this embodiment is closer to the transmission optical waveguide, the electric field can act more strongly on the transmission optical waveguide 216, thereby effectively improving the modulation efficiency.

[0071] The signal electrode 213 shown in this embodiment includes a first conductive layer 231 and a second conductive layer 232 in a stacked structure. The second conductive layer 232 has a low conductivity, for example, the conductivity of the second conductive layer 232 is in the range of 10. 3 ~10 5 Within the Siemens / meter (s / m) range. A second conductive layer 232 with lower conductivity increases microwave loss in electrical signal transmission. However, the signal electrode 213 also includes a first conductive layer 231 with higher conductivity; for example, the conductivity of the first conductive layer 231 is equal to 10. 7 The first conductive layer 231, with its high conductivity, exhibits superior conductivity, which reduces microwave loss and thus increases the modulation bandwidth. Therefore, in this embodiment, a high-conductivity first conductive layer 231 is stacked above the second conductive layer 232 to compensate for the microwave loss caused by the low-conductivity second conductive layer 232.

[0072] To better understand the spatial relationship between the first conductive layer 231 and the second conductive layer 232 included in the signal electrode 213, the following is combined with Figure 2a , Figure 2b as well as Figure 2c The specific directions shown will be explained. In this embodiment, the transmission optical waveguide 216 extends along the Y direction. It can be seen that the optical signal transmitted along the transmission optical waveguide 216 is transmitted along the Y direction. In this embodiment, the first conductive layer 231 and the second conductive layer 232 are stacked along the X direction, wherein the X direction is perpendicular to the Y direction and also perpendicular to the substrate surface.

[0073] This embodiment does not limit the length relationship between the first conductive layer 231 and the second conductive layer 232 along the Z direction. The Z direction is perpendicular to both the X and Y directions. For example, in... Figure 2b as well as Figure 2cIn the example shown, along the Z direction, the length of the second conductive layer 232 is less than the length of the first conductive layer 231, and the second conductive layer 232 is disposed within the first conductive layer 231. Along the X direction, the side surface of the first conductive layer 231 is aligned with the side surface of the second conductive layer 232, thus it can be seen that... Figure 2c In the top view shown, the second conductive layer 232 is completely concealed within the first conductive layer 231.

[0074] It needs to be made clear that, Figure 2b as well as Figure 2c The structure shown is an example and is not intended to be limiting. For example... Figure 3a as well as Figure 3b As shown. Among them, Figure 3a This is a second cross-sectional structural example of the electro-optic modulator provided in the embodiments of this application. Figure 3b This is a second top view example of the electro-optic modulator provided in the embodiments of this application. In this example, along the Z direction, the second conductive layer 232 protrudes beyond the first conductive layer 231. It can be seen that along the X direction, the side surface of the first conductive layer 231 is not aligned with the side surface of the second conductive layer 232, and the side surface of the second conductive layer 232 is closer to the transmission optical waveguide 216 than the side surface of the first conductive layer 231.

[0075] It can be seen that, along the Z-direction, when the length of the second conductive layer 232 is less than the length of the first conductive layer 231, a portion of the side of the first conductive layer 231 facing the substrate contacts the second conductive layer 232. Specifically, the side of the first conductive layer 231 facing the substrate has a connected first region and a second region. The first region directly contacts the second conductive layer 232, while the second region directly contacts the optical waveguide layer 212.

[0076] In other examples, the length of the second conductive layer 232 along the Z direction may also be greater than or equal to the length of the first conductive layer 231. It is understood that in this example, the entire area of ​​the side of the first conductive layer 231 facing the substrate is in contact only with the second conductive layer 232.

[0077] As shown above, the first electrode (signal electrode or ground electrode) in this embodiment adopts a stacked structure, which reduces the distance between the first electrode and the transmission optical waveguide. This improves modulation efficiency while reducing optical loss and increasing modulation bandwidth. Furthermore, because the distance between the first electrode and the transmission optical waveguide in the electro-optic modulator shown in this embodiment is relatively small, the size of the electro-optic modulator is effectively reduced, and the integration density of the electro-optic modulator is improved.

[0078] The above example illustrates an electro-optic modulator where only the first electrode employs a stacked structure. The second electrode in this embodiment can also be stacked. For instance, if the first electrode is a signal electrode, then the second electrode is a ground electrode. Similarly, if the first electrode is a ground electrode, then the second electrode is a signal electrode. Therefore, both the ground electrode and the signal electrode in this embodiment employ a stacked structure.

[0079] See details Figure 2b As shown, taking the second electrode as an example of a ground electrode 214, the ground electrode 214 specifically includes a third conductive layer 233 and a fourth conductive layer 234. The fourth conductive layer 234 is located between the substrate and the third conductive layer 233. The conductivity of the third conductive layer 233 is greater than that of the fourth conductive layer 234, and the light absorption coefficient of the third conductive layer 233 is greater than that of the fourth conductive layer 234. For a detailed description of the specific structure of the ground electrode 214, please refer to the above description of the structure of the signal electrode 213, which will not be repeated here.

[0080] This embodiment does not limit the length relationship between the third conductive layer 233 and the fourth conductive layer 234 along the Z direction. This embodiment takes an example where the length of the third conductive layer 233 is greater than the length of the fourth conductive layer 234. It can be seen that a portion of the side of the third conductive layer 233 facing the substrate is in contact with the fourth conductive layer 234. Specifically, the side of the third conductive layer 233 facing the substrate has a connected third region and a fourth region. The third region is in direct contact with the fourth conductive layer 234, while the fourth region is in direct contact with the optical waveguide layer 212.

[0081] As can be seen, in this example, the spacing between the first electrode and the transmission optical waveguide, as well as the spacing between the second electrode and the transmission optical waveguide, can be reduced simultaneously. Compared to examples where only the first electrode uses a stacked structure, this example can improve modulation efficiency and modulation bandwidth, as well as reduce optical and microwave losses. Furthermore, it can further reduce the size of the electro-optic modulator and improve its integration.

[0082] Continue as Figure 2bAs shown, the ground electrode 215 also includes a third conductive layer 243 and a fourth conductive layer 244. For a description of the third conductive layer 243 and the fourth conductive layer 244 included in the ground electrode 215, please refer to the description of the third conductive layer 233 and the fourth conductive layer 234 included in the ground electrode 214 shown above. In this example, the side of the signal electrode 213 facing the ground electrode 215 includes a first conductive layer 251 and a second conductive layer 252. For a description of the first conductive layer 251 and the second conductive layer 252 included in the signal electrode 213, please refer to the description of the first conductive layer 231 and the second conductive layer 232 included in the signal electrode 213 shown above. It can be seen that the signal electrode 213, the ground electrode 214, and the ground electrode 215 shown in this embodiment all adopt a stacked structure.

[0083] like Figure 4a as well as Figure 4b The diagram illustrates how to reduce the parasitic capacitance between the signal electrode and the ground electrode. Specifically, Figure 4a This is an example diagram of an overall structure of the electro-optic modulator provided in an embodiment of this application. Figure 4b This is a top view example of a third type of electro-optic modulator provided in an embodiment of this application.

[0084] The electro-optic modulator shown in this embodiment includes a signal electrode 213 and a ground electrode 214 arranged in a stacked structure. For a description of these two electrodes, please refer to [link to documentation]. Figures 2a to 3b As shown, details are not elaborated further. In this embodiment, both the first conductive layer 231 and the third conductive layer 233 employ a concave-convex structure. Specifically, the concave-convex structure of the first conductive layer 231 means that multiple first upper protrusions 301 protrude from the side of the first conductive layer 231 facing the third conductive layer 233. A first upper recess 303 is formed between any two adjacent first upper protrusions 301. The concave-convex structure of the third conductive layer 233 means that multiple second upper protrusions 302 protrude from the side of the third conductive layer 233 facing the first conductive layer 231. A second upper recess 304 is formed between any two adjacent second upper protrusions 302.

[0085] To reduce the parasitic capacitance between the signal electrode 213 and the ground electrode 214, each of the first upper protrusions 301 is positioned opposite to one of the second upper recesses 304. Similarly, each of the second upper protrusions 302 is positioned opposite to one of the first upper recesses 303. It is understood that in this embodiment, the first upper protrusions 301 and the second upper protrusions 302 are not positioned opposite each other. Because each of the first upper protrusions 301 and the second upper recesses 304 are opposite each other, and each of the second upper protrusions 302 and the first upper recesses 303 are opposite each other, the positions of the first upper protrusions 301 and the second upper protrusions 302 are staggered along the Z-direction, thereby maximizing the spacing between the first conductive layer 231 and the third conductive layer 233. This effectively reduces the parasitic capacitance between the signal electrode 213 and the ground electrode 214. For a detailed explanation of the Z-direction, please refer to the above. Figure 2b As shown, the specifics will not be elaborated further.

[0086] Taking the first upper protrusion 301 as an example, this embodiment does not limit the specific shape and size of the first upper protrusion 301. For example, Figure 4a and Figure 4b The example shown uses a square shape for the first upper protrusion 301, but this is not a limitation. In other examples, the shape of the first upper protrusion 301 can also be trapezoidal, arc-shaped, rhomboid, T-shaped, or conical. For a description of the shape of the second upper protrusion 302, please refer to the description of the shape of the first upper protrusion 301; details will not be repeated here.

[0087] Taking the first upper protrusion 301 as an example, one first upper protrusion 301 and one first upper recess 303 are adjacent. It can be seen that the adjacent first upper protrusions 301 are in a discontinuous state, which will increase the microwave loss of the first conductive layer 231.

[0088] The following describes how to reduce microwave loss of the signal electrode 213 as shown in this embodiment. The signal electrode 213 shown in this embodiment includes multiple upper structure cycles. Each upper structure cycle includes at least one first upper protrusion 301 and at least one first upper recess 303 located adjacent to each other. Different upper structure cycles have the same structure. For example, Figure 4b As shown, the signal electrode 213 includes an upper structure cycle 305 comprising a first upper protrusion 301 and a first upper recess 303 located adjacent to each other. This embodiment does not limit the number of first upper protrusions 301 and first upper recesses 303 included in each upper structure cycle, as long as the positions of the first upper protrusions 301 and first upper recesses 303 included in an upper structure cycle are consecutive.

[0089] The structural similarity across different upper structural cycles in this embodiment refers to the identical dimensions of the first upper protrusion 301 located at the same position in different structural cycles. Specifically, the first upper protrusion 301 located at the same position in different structural cycles refers to the first upper protrusion 301 in each structural cycle, and so on, up to the last upper protrusion 301 in each structural cycle. The dimensions of the first upper protrusion 301 refer to its length along the Z-direction, its length along the Y-direction, and its height along the X-direction.

[0090] The structural similarity of different upper structure cycles shown in this embodiment also refers to the fact that the dimensions of the first upper recess 303 located at the same position in different structure cycles are the same. Specifically, the first upper recess 303 located at the same position in different structure cycles refers to the first upper recess 303 in each different structure cycle, and so on, up to the last upper recess 303 in each different structure cycle. The dimensions of the first upper recess 303 refer to its length along the Z direction and its length along the Y direction.

[0091] In this embodiment, the microwave loss of the first upper protrusion 301 can be reduced by the upper structure period. Specifically, along the extension direction (i.e., the Y direction) of the signal electrode 213, the number of upper structure periods included in the signal electrode 213 per unit length is positively correlated with the modulation bandwidth of the electro-optic modulator. Here, the unit length is only a reference standard, and the specific length of the unit length is not limited in this embodiment.

[0092] For signal electrodes employing a stacked structure, the more upper-layer structure periods per unit length, the more continuous the signal electrode structure of the electro-optic modulator. This results in lower microwave loss from the signal electrodes, and consequently, a larger modulation bandwidth for the electro-optic modulator. Conversely, fewer upper-layer structure periods per unit length indicate a more loosely structured signal electrode structure. This leads to higher microwave loss from the signal electrodes, and consequently, a smaller modulation bandwidth for the electro-optic modulator.

[0093] As can be seen, in order to improve the modulation bandwidth of the electro-optic modulator, this embodiment can increase the number of upper structure cycles included in the signal electrode 213 within a unit length as much as possible.

[0094] In this embodiment, the first conductive layer 231 is illustrated by exemplifying a periodic arrangement based on the periodicity of the upper structure, without limitation. For example, in other examples, the dimensions of the first upper protrusion 301 and the first upper recess 303 included in the first conductive layer 231 can also be arranged randomly. For details on how the grounding electrode reduces microwave loss as shown in this embodiment, please refer to the description of reducing microwave loss in the signal electrode 213; specific details will not be elaborated here.

[0095] based on Figure 4a as well as Figure 4b The structures of the first conductive layer 231 and the third conductive layer 233 shown are illustrated below. The optional structures of the second conductive layer 232 and the fourth conductive layer 234 shown in this embodiment will also be described below. The structure of the second conductive layer 232 will be used as an example for illustrative purposes. The structure of the fourth conductive layer 234 can be found in the following description of the structure of the second conductive layer 232, and will not be repeated here.

[0096] The second conductive layer 232 shown in this embodiment can be a continuous strip structure. Along the Y direction, the second conductive layer 232 extends from the starting position of the first conductive layer 231 to the ending position of the first conductive layer 231. The description of the shape of the second conductive layer 232 in this embodiment is an optional example and is not limited, as long as the second conductive layer 232 has a continuous structure. For example, the second conductive layer 232 can be arc-shaped, etc. This embodiment does not limit the length relationship between the first conductive layer 231 and the second conductive layer 232 along the Y direction; for example, along the Y direction, the length of the first conductive layer 231 and the length of the second conductive layer 232 are equal. It can be seen that in... Figure 4b In the top view shown, the side of the second conductive layer 232 facing away from the substrate has a fifth region and a sixth region. The fifth region is in direct contact with the first upper layer protrusion 301. Figure 4b As shown in the top view, the sixth region 321 is directly exposed from the first upper recess 303.

[0097] As described above, to reduce the parasitic capacitance of the electro-optic modulator, the first conductive layer 231 and the third conductive layer 233 can adopt a periodic structure. In this embodiment, to further reduce the parasitic capacitance of the electro-optic modulator, the second conductive layer 232 and the fourth conductive layer 234 can also adopt a concave-convex structure.

[0098] Specifically, the concave-convex structure of the second conductive layer 232 means that a plurality of first lower layer protrusions are provided on the side of the second conductive layer 232 facing the fourth conductive layer 234, and a first lower layer recess is formed between any two adjacent first lower layer protrusions. The description of the structure of the first lower layer protrusions and the first lower layer recesses can be found in the description of the structure of the first upper layer protrusion 301 and the first upper layer recess 303 shown above, and will not be repeated here.

[0099] The concave-convex structure of the fourth conductive layer 234 refers to the fact that the fourth conductive layer 234 has multiple second lower layer protrusions protruding from the side of the second conductive layer 232, and a second lower layer recess is formed between any two adjacent second lower layer protrusions. The description of the structure of the second lower layer protrusions and the second lower layer recesses can be found in the description of the structure of the second upper layer protrusion 302 and the second upper layer recess 304 shown above, and will not be repeated here.

[0100] To further reduce the parasitic capacitance between the signal electrode 213 and the ground electrode 214, each of the first lower layer protrusions is positioned opposite a second lower layer recess. Similarly, each of the second lower layer protrusions is positioned opposite a first lower layer recess.

[0101] It is known that each of the first lower layer protrusions is positioned opposite to one of the first lower layer recesses, and each of the second lower layer protrusions is positioned opposite to one of the second lower layer recesses. Therefore, along the Z-direction, the positions of the first and second lower layer protrusions are staggered, thereby maximizing the spacing between the second conductive layer 232 and the fourth conductive layer 234. This effectively reduces the parasitic capacitance between the signal electrode 213 and the ground electrode 214.

[0102] Therefore, to reduce the parasitic capacitance between the signal electrode 213 and the ground electrode 214, both the first conductive layer 231 and the second conductive layer 232 adopt a periodic structure. The positional relationship between the concave-convex structure of the first conductive layer 231 and the second conductive layer 232 is optionally described below. For example, the concave-convex structures of the first conductive layer 231 and the second conductive layer 232 may coincide. This coincidence means that, under the illumination of the same projection line, the projection positions of each first upper protrusion 301 included in the first conductive layer 231 and one first lower protrusion included in the second conductive layer 232 on the substrate coincide. Furthermore, under the illumination of the same projection line, the projection positions of each first upper recess 303 included in the first conductive layer 231 and one first lower recess included in the second conductive layer 232 on the substrate coincide. This embodiment does not limit the specific direction of the projection line; for example, the projection line may be a ray perpendicular to the substrate direction.

[0103] See also Figure 5 As shown, where, Figure 5This is a top-view example of a fourth electro-optic modulator structure provided in this application embodiment. The concave-convex structure of the first conductive layer 231 and the concave-convex structure of the second conductive layer 232 coincide in position, and from the top-view perspective of the electro-optic modulator, the optical waveguide layer 212 is exposed sequentially from the first lower recess and the first upper recess 303. The concave-convex structures of the third conductive layer 233 and the fourth conductive layer 234 shown in this embodiment coincide in position. For a detailed explanation, please refer to the explanation of the coincidence of the concave-convex structures of the first conductive layer 231 and the second conductive layer 232; further details will not be repeated here.

[0104] Similarly, under the same projection lines, the projection positions of each of the second upper protrusions 302 included in the third conductive layer 233 and one of the second lower protrusions included in the fourth conductive layer 234 coincide on the substrate. Furthermore, under the same projection lines, the projection positions of each of the second upper recesses included in the third conductive layer 233 and one of the second lower recesses included in the fourth conductive layer 234 coincide on the substrate. For detailed explanations, please refer to the above description of the concave-convex structure of the first conductive layer 231 and the second conductive layer 232; further details will not be repeated here.

[0105] It is understood that when the concave-convex structures of the first conductive layer 231 and the second conductive layer 232 coincide, and the concave-convex structures of the third conductive layer 233 and the fourth conductive layer 234 coincide, the spacing between the first upper protrusion 301 and the second upper protrusion 302, as well as the spacing between the first upper protrusion 301 and the second lower protrusion, can be significantly increased. This effectively reduces the parasitic capacitance between the signal electrode 213 and the ground electrode 214. Furthermore, it reduces the difficulty of fabricating the signal electrode and the ground electrode.

[0106] It should be clarified that this embodiment is illustrated by the example of the overlapping positions of the concave-convex structure of the first conductive layer 231 and the concave-convex structure of the second conductive layer 232, and is not intended to be limiting. In other examples, the concave-convex structures of the first conductive layer 231 and the second conductive layer 232 may be staggered. For example, from a top-view perspective of the electro-optic modulator, at least a portion of a first lower protrusion included in the second conductive layer 232 is exposed from a first upper recess included in the first conductive layer 231.

[0107] Continuing with the example of the first lower protrusion, the following explains how to reduce the microwave loss of the signal electrode 213. The signal electrode 213 shown in this embodiment includes multiple lower structure cycles. Each lower structure cycle includes at least one first lower protrusion and at least one first lower recess located adjacent to each other. Different lower structure cycles have the same structure. For a description of the structure of the lower structure cycles, please refer to the above description of the upper structure cycles; details will not be repeated here.

[0108] As can be seen, in this embodiment, the microwave loss of the first lower protrusion can be reduced by the lower structure period. Specifically, along the extension direction of the signal electrode 213 (i.e., the Y direction), the number of lower structure periods included in the signal electrode 213 per unit length is positively correlated with the modulation bandwidth of the electro-optic modulator. For an explanation of the process by which the lower structure period reduces the microwave loss of the first lower protrusion, please refer to the above explanation of the process by which the upper structure period reduces the microwave loss of the first upper protrusion; further details will not be repeated here.

[0109] See below Figure 6a and Figure 6b As shown. Among them, Figure 6a This is an example of a third cross-sectional structure of the electro-optic modulator provided in the embodiments of this application. Figure 6b This is a top view example of the fifth electro-optic modulator provided in the embodiments of this application.

[0110] The electro-optic modulator shown in this embodiment also includes an electric field confinement layer. Several optional structures of this electric field confinement layer are described below.

[0111] Option structure 1, for the signal electrode 213 and the ground electrode 214, the electro-optic modulator shown in this embodiment includes a first electric field confinement layer 601 and a second electric field confinement layer 602. The first electric field confinement layer 601 is located between the transmission optical waveguide 216 and the signal electrode 213. The second electric field confinement layer 602 is located between the transmission optical waveguide 216 and the ground electrode 214. It should be clearly stated that the description of the number of electric field confinement layers in this embodiment is an optional example and is not limited. For example, the electro-optic modulator may only include the first electric field confinement layer 601 located between the transmission optical waveguide 216 and the signal electrode 213. Or, the electro-optic modulator may only include the second electric field confinement layer 602 located between the transmission optical waveguide 216 and the ground electrode 214.

[0112] The specific locations of the first electric field confinement layer 601 and the second electric field confinement layer 602 are described below. The first electric field confinement layer 601 shown in this embodiment has a first side and a second side that are opposite in position. The first side and the second side refer to the two sides of the first electric field confinement layer 601 that face opposite directions along the Z-direction. It can be seen that the first side faces the signal electrode 213, while the second side faces the transmission optical waveguide 216. The first side and the signal electrode 213 are adjacent in position. This embodiment does not limit the distance between the first side and the signal electrode 213 along the Z-direction. For example, Figure 6a and Figure 6b As shown, the first side is in contact with the signal electrode 213. The second side is adjacent to the transmission optical waveguide 216. In this embodiment, the distance between the second side and the transmission optical waveguide 216 along the Z direction is not limited. Similarly, the second electric field confinement layer 602 also has a first side and a second side located opposite each other. The first side of the second electric field confinement module 602 is adjacent to the ground electrode 214, and the second side is adjacent to the transmission optical waveguide 216. For a detailed description, please refer to the description of the first and second sides of the first electric field confinement layer 601, which will not be repeated here.

[0113] It can be seen that both the first electric field confinement layer 601 and the second electric field confinement layer 602 are continuous structures. That is, along the Y direction, the first electric field confinement layer 601 extends from the starting position of the signal electrode 213 to the ending position of the signal electrode 213. The description of the shape of the first electric field confinement layer 601 in this embodiment is an optional example and is not limited, as long as the first electric field confinement layer 601 has a continuous structure, for example, the first electric field confinement layer 601 can be elongated or arc-shaped. This embodiment does not limit the length relationship between the first electric field confinement layer 601 and the signal electrode 213 along the Y direction. For example, along the Y direction, the length of the first electric field confinement layer 601 is equal to the length of the signal electrode 213. For the description of the structure of the second electric field confinement layer 602 along the Y direction, please refer to the description of the first electric field confinement layer 601, and will not be repeated here.

[0114] Optionally, such as Figure 6a As shown, along the X direction, the height of the first electric field confinement layer 601 is equal to the height of the signal electrode 213. It should be clearly stated that the description of the height relationship between the first electric field confinement layer 601 and the signal electrode 213 along the X direction in this embodiment is an optional example and is not limited. For example, along the X direction, the height of the first electric field confinement layer 601 may be greater than the height of the signal electrode 213.

[0115] The first electric field confinement layer 601 and the second electric field confinement layer 602 shown in this embodiment satisfy the following conditions: both the first electric field confinement layer 601 and the second electric field confinement layer 602 are made of a high dielectric constant and an insulating material. Furthermore, the refractive index of both the first electric field confinement layer 601 and the second electric field confinement layer 602 is less than the refractive index of the material of the transmission optical waveguide 216. For example, both the first electric field confinement layer 601 and the second electric field confinement layer 602 can be made of barium titanate (BaTiO3).

[0116] The first electric field confinement layer 601 and the second electric field confinement layer 602, satisfying this condition, enable the electric field between the signal electrode 213 and the ground electrode 214 to be mainly distributed on the transmission optical waveguide 216, thereby improving the modulation efficiency of the optical signal transmitted by the modulation transmission optical waveguide 216. Specifically, the first electric field confinement layer 601 and the second electric field confinement layer 602 can concentrate the electric field between the signal electrode 213 and the ground electrode 214 as much as possible between the first electric field confinement layer 601 and the second electric field confinement layer 602. Because the transmission optical waveguide 216 is located between the first electric field confinement layer 601 and the second electric field confinement layer 602, and is closer to the first electric field confinement layer 601 than to the signal electrode 213, and similarly, is closer to the second electric field confinement layer 602 than to the ground electrode 214, the electric field concentrated between the first electric field confinement layer 601 and the second electric field confinement layer 602 can be mainly concentrated on the transmission optical waveguide 216. This enhances the interaction between the electric field and the optical field of the optical signal transmitted by the transmission optical waveguide 216, thereby improving the modulation efficiency.

[0117] Furthermore, since both the first electric field confinement layer 601 and the second electric field confinement layer 602 shown in this embodiment are made of insulating materials, neither the first electric field confinement layer 601 nor the second electric field confinement layer 602 has conductive properties, thus avoiding microwave loss. Therefore, the electro-optic modulator including the electric field confinement layer does not reduce the modulation bandwidth.

[0118] Optional structure 2, the electro-optic modulator shown in this example includes a plurality of electric field confinement layers 611. The electric field confinement layer 611 extends to at least one of the following locations: the side of the first upper convex portion of the signal electrode 213 facing the transmission optical waveguide 216, the side of the first upper recess of the signal electrode 213, the side of the first lower convex portion of the signal electrode 213 facing the transmission optical waveguide 216, the side of the first lower recess of the signal electrode 213, the side of the second upper convex portion of the ground electrode facing the transmission optical waveguide 216, the side of the second upper recess of the ground electrode, the side of the second lower convex portion of the ground electrode facing the transmission optical waveguide 216, or the side of the second lower recess of the ground electrode.

[0119] Figure 7aThis is a top view example of a sixth type of electro-optic modulator provided in the embodiments of this application. As can be seen, this example is based on the fact that an electric field confinement layer 611 is attached to the side of each first upper recess and an electric field confinement layer 611 is attached to the side of each second upper recess. Figure 7b This is a top view example of a seventh electro-optic modulator structure provided in an embodiment of this application. As can be seen, this example uses the case where each first upper recess is filled with an electric field confinement layer 612, and each second upper recess is filled with an electric field confinement layer 612. It should be clarified that this embodiment does not limit the specific number or location of the electric field confinement layers 611.

[0120] Figure 8 This is an example diagram of a fourth cross-sectional structure embodiment of the electro-optic modulator provided in this application. (See diagram below.) Figure 8 As shown, the substrate of the electro-optic modulator includes an optical waveguide layer 801 and a substrate 802 located on the surface of the optical waveguide layer 801. For a description of the specific materials of the substrate 802 and the optical waveguide layer 801, please refer to [link to relevant documentation]. Figure 2b As shown, the specifics will not be elaborated further.

[0121] The surface of the substrate 802 includes a signal electrode 811 and ground electrodes 812 and 813 located on both sides of the signal electrode 811. In this embodiment, the signal electrode 811, ground electrode 812, and ground electrode 813 all adopt a stacked structure. For a description of the stacked electrode structure, please refer to [link to documentation]. Figures 2a to 3b As shown, the specifics will not be elaborated further.

[0122] The electro-optic modulator shown in this embodiment also includes a transmission optical waveguide. For example, the electro-optic modulator shown in this embodiment includes a transmission optical waveguide 803 formed by an optical waveguide layer 801. The optical waveguide layer 801 can be formed into the transmission optical waveguide 803 by deposition, etching, polarization, or other methods. The transmission optical waveguide 803 and the signal electrode 811 are located on opposite sides of the substrate 802, i.e., along the X-direction, the transmission optical waveguide 803 and the signal electrode 811 are positioned opposite each other. This embodiment uses the example of a transmission optical waveguide 803 positioned along the X-direction opposite to the signal electrode 811 for illustrative purposes, and is not intended to be limiting. For example, in other examples, a transmission optical waveguide 804 is also positioned along the X-direction opposite to the ground electrode 812.

[0123] The electro-optic modulator shown in this embodiment also includes an electric field confinement layer. Specifically, if a transmission optical waveguide 803 is disposed along the X direction opposite to the position of the signal electrode 811, then the substrate 802 includes a first through-slot. The first through-slot is located between the signal electrode 811 and the transmission optical waveguide 803. An electric field confinement layer is disposed within the first through-slot. Alternatively, if a transmission optical waveguide 804 is disposed along the X direction opposite to the position of the ground electrode 812, then the substrate 802 includes a second through-slot. The second through-slot is located between the ground electrode 812 and the transmission optical waveguide 804, and an electric field confinement layer is disposed within the second through-slot. For a description of the specific material and function of the electric field confinement layer shown in this embodiment, please refer to [link to documentation]. Figure 6a As shown, the specifics will not be elaborated further.

[0124] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electro-optic modulator, characterized by The electro-optical modulator comprises a first electrode and a second electrode on a surface of a substrate, and further comprises a transmission optical waveguide, and an electric field between the first electrode and the second electrode is used to modulate an optical signal transmitted by the transmission optical waveguide. The first electrode comprises a first conductive layer and a second conductive layer, the second conductive layer is between the substrate and the first conductive layer, the conductivity of the first conductive layer is greater than that of the second conductive layer, and the light absorption coefficient of the first conductive layer is greater than that of the second conductive layer, wherein the first conductive layer is made of metal material, and the second conductive layer is made of transparent conductive oxide (TCO).

2. The electro-optic modulator of claim 1, wherein, The second electrode comprises a third conductive layer and a fourth conductive layer, the fourth conductive layer is between the substrate and the third conductive layer, the conductivity of the third conductive layer is greater than that of the fourth conductive layer, and the light absorption coefficient of the third conductive layer is greater than that of the fourth conductive layer.

3. The electro-optic modulator of claim 2, wherein, The side of the first conductive layer facing the third conductive layer is provided with a plurality of first upper layer protrusions, and a first upper layer recess is formed between any two adjacent first upper layer protrusions at any position. The side of the third conductive layer facing the first conductive layer is provided with a plurality of second upper layer protrusions, and a second upper layer recess is formed between any two adjacent second upper layer protrusions at any position. Each first upper layer protrusion is located opposite to a second upper layer recess, and each second upper layer protrusion is located opposite to a first upper layer recess.

4. The electro-optic modulator of claim 3, wherein, The side of the second conductive layer facing the fourth conductive layer is provided with a plurality of first lower layer protrusions, and a first lower layer recess is formed between any two adjacent first lower layer protrusions at any position. The side of the fourth conductive layer facing the second conductive layer is provided with a plurality of second lower layer protrusions, and a second lower layer recess is formed between any two adjacent second lower layer protrusions at any position. Each first lower layer protrusion is located opposite to a second lower layer recess, and each second lower layer protrusion is located opposite to a first lower layer recess.

5. The electro-optic modulator of claim 4, wherein, The projection position of each first upper layer protrusion included in the first conductive layer and a first lower layer protrusion included in the second conductive layer on the substrate is coincident.

6. The electro-optic modulator of claim 4 or 5, wherein, The projection position of each second upper layer protrusion included in the third conductive layer and a second lower layer protrusion included in the fourth conductive layer on the substrate is coincident.

7. The electro-optic modulator of claim 3 or 5, wherein, The first electrode comprises a plurality of upper layer structure periods, each upper layer structure period comprises at least one first upper layer protrusion and at least one first upper layer recess located adjacent to each other, the structures of different upper layer structure periods are the same, and the number of upper layer structure periods included in the first electrode per unit length and the modulation bandwidth of the electro-optical modulator are in a positive correlation relationship along the extension direction of the first electrode.

8. The electro-optic modulator of claim 4 or 5, wherein, The first electrode comprises a plurality of lower structure periods, each of the lower structure periods comprises at least one first lower protrusion and at least one first lower recess which are located adjacently, and the structure of different lower structure periods is identical, and the number of the lower structure periods included in a unit length of the first electrode along the extension direction of the first electrode and the modulation bandwidth of the electro-optical modulator are in a positive correlation.

9. The electro-optic modulator of any one of claims 1 to 5, wherein, The electro-optical modulator further comprises an electric field confinement layer, the electric field confinement layer is located between the transmission optical waveguide and the first electrode, and / or the electric field confinement layer is located between the transmission optical waveguide and the second electrode, and the electric field confinement layer is used to make the electric field distribute on the transmission optical waveguide.

10. The electro-optic modulator of claim 9, wherein, The transmission optical waveguide is located on the surface of the substrate, and the electric field confinement layer has a first side and a second side which are located oppositely, the first side is located adjacently to the first electrode, or the first side is located adjacently to the second electrode, and the second side is located adjacently to the transmission optical waveguide.

11. The electro-optic modulator of claim 9, wherein, The electric field confinement layer extends to at least one of the following positions: The first upper protrusion included in the first electrode, the first upper recess included in the first electrode, the first lower protrusion included in the first electrode, the first lower recess included in the first electrode, the second upper protrusion included in the second electrode, the second upper recess included in the second electrode, the second lower protrusion included in the second electrode, or the second lower recess included in the second electrode.

12. The electro-optic modulator of any one of claims 1 to 5, wherein, The transmission optical waveguide and the first electrode are located on two sides of the substrate, and / or the transmission optical waveguide and the second electrode are located on two sides of the substrate. The substrate further comprises an electric field confinement layer, the electric field confinement layer is located between the transmission optical waveguide and the first electrode, and / or the electric field confinement layer is located between the transmission optical waveguide and the second electrode, and the electric field confinement layer is used to make the electric field mainly distribute on the transmission optical waveguide.

13. The electro-optic modulator of claim 9, wherein, The electric field confinement layer is made of a material with high dielectric constant and insulation, and the material refractive index of the electric field confinement layer is smaller than the material refractive index of the transmission optical waveguide.

14. The electro-optic modulator of any one of claims 1 to 5, wherein, The side of the first conductive layer facing the substrate comprises a first area and a second area, the first area is in contact with the second conductive layer, and the second area is in contact with the substrate.

15. The electro-optic modulator of any one of claims 2 to 5, wherein, The side of the third conductive layer facing the substrate comprises a third area and a fourth area, the third area is in contact with the fourth conductive layer, and the fourth area is in contact with the substrate.

16. An optical module characterized by comprising: The optical module comprises a light source and the electro-optical modulator according to any one of claims 1 to 15, the light source is connected with the transmission optical waveguide, and the light source is used to send an optical signal to the transmission optical waveguide.

17. An optical transmitting device, characterized in that, The optical transmitting device comprises a processor and the optical module according to claim 16, the processor is connected with a signal electrode, the signal electrode is the first electrode or the second electrode, the processor is used to send an electrical signal to the signal electrode, and the electrical signal is used to modulate an optical signal transmitted by the transmission optical waveguide.

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