Y-type thin film lithium niobate electro-optic modulator and manufacturing method thereof

Abstract

The application provides a Y-shaped thin film lithium niobate electro-optical modulator and a manufacturing method. A lithium niobate layer on an electro-optical modulator chip is etched into a corresponding curved waveguide structure, and two curved waveguide structures are symmetrically arranged on both sides of the Y-shaped waveguide structure, so that the heights of two light paths are consistent. The curved waveguide structure reduces the space size required by the waveguide while ensuring the waveguide length. For the waveguide with the same length, a chip with a smaller length can be used for mounting. The signal electrode and the ground electrode are arranged on both sides of each straight waveguide in the curved waveguide structure, the optical signal in the waveguide is modulated, and the modulation requirement of the electro-optical modulator is realized.

Description

Technical Field

[0001] This invention belongs to the field of integrated optics, and in particular relates to a Y-type thin-film lithium niobate electro-optic modulator and its fabrication method. Background Technology

[0002] Electro-optic modulation, by loading electrical signals onto optical signals, enables long-distance, low-loss information transmission and forms the foundation of modern communication networks. Thin-film lithium niobate materials, due to their combination of high integration and excellent electro-optic coefficients, can realize low-power, small-size electro-optic modulation devices, showing great potential in the field of electro-optic modulation. Currently used thin-film lithium niobate structures are generally X-cut lithium niobate films, with electrodes typically located on both sides of the waveguide to achieve alignment of the electric field with the optical axis, maximizing the electro-optic coefficient and resulting in high modulation efficiency. However, this arrangement introduces challenges, such as the simultaneous presence of optical and electrical structures on the chip surface, requiring consideration of various crosstalk factors and the space occupied by both structures.

[0003] Therefore, overcoming the shortcomings of the existing technology is an urgent problem to be solved in this technical field. Summary of the Invention

[0004] The technical problem to be solved by this invention is how to arrange the corresponding waveguide structure and electrodes on an electro-optic modulator, while reducing the space occupied by the waveguide structure and electrodes under the premise that the electric field direction is consistent with the optical axis.

[0005] The present invention adopts the following technical solution:

[0006] In a first aspect, a Y-type thin-film lithium niobate electro-optic modulator is provided, comprising: a lithium niobate layer 1, an electrode 2, and an oxide layer 3, wherein:

[0007] The lithium niobate layer 1 is disposed on the oxide layer 3;

[0008] The lithium niobate layer 1 includes a first Y-shaped waveguide structure 11 and two curved waveguide structures 12. The two curved waveguide structures 12 are symmetrically arranged on both sides of the first Y-shaped waveguide structure 11 and are connected to the first Y-shaped waveguide structure 11.

[0009] The curved waveguide structure 12 includes multiple straight waveguides 121 and multiple curved waveguides 122. The multiple straight waveguides 121 are arranged in parallel to each other, and adjacent straight waveguides 121 are connected end to end through the curved waveguides 122 to connect all straight waveguides 121 in the same curved waveguide structure 12 together.

[0010] The electrode 2 is located on the lithium niobate layer 1. The electrode 2 includes a signal electrode 21 and a ground electrode 22. The ground electrode 22 and the signal electrode 21 are respectively disposed on both sides of each straight waveguide 121. The signal electrode 21 and the ground electrode 22 are respectively disposed parallel to the straight waveguide 121, thereby ensuring that the electric field direction generated by the ground electrode 22 and the signal electrode 21 is perpendicular to the straight waveguide 121.

[0011] Preferably, the Y-type thin-film lithium niobate electro-optic modulator further includes: a substrate 4 and a buffer layer 5, wherein:

[0012] The substrate 4 is located below the oxide layer 3;

[0013] The buffer layer 5 is disposed between the lithium niobate layer 1 and the electrode 2.

[0014] Preferably, the first Y-shaped waveguide structure 11 includes a first main waveguide 111 and two first branch waveguides 112, wherein:

[0015] The first main waveguide 111 and the two first branch waveguides 112 are respectively connected;

[0016] One of the first branch waveguides 112 is connected to one of the curved waveguide structures 12, and the other first branch waveguide 112 is connected to the other curved waveguide structure 12.

[0017] Preferably, the adjacent straight waveguides 121 are connected end-to-end through the curved waveguides 122 to connect all the straight waveguides 121 in the same curved waveguide structure 12 in series, specifically including:

[0018] Each of the curved waveguide structures 12 includes a plurality of straight waveguides 121. According to the distance of the straight waveguides 121 relative to the first Y-shaped waveguide structure 11, each of the curved waveguide structures 12 specifically includes the first straight waveguide 121 to the j-th straight waveguide 121, where j>1 and j is an odd number.

[0019] For the first straight waveguide 121, the first end of the first straight waveguide 121 is connected to the first Y-shaped waveguide structure 11, and the second end of the first straight waveguide 121 is connected to the second straight waveguide 121 through a bent waveguide 122;

[0020] For the j-th straight waveguide 121, the first end of the j-th straight waveguide 121 is connected to the (j-1)-th straight waveguide 121 through a bent waveguide 122, and the second end of the j-th straight waveguide 121 is used for optical signal output;

[0021] For the straight waveguides 121 other than the first straight waveguide 121 and the jth straight waveguide 121, the two ends of the straight waveguide 121 are respectively connected to the two adjacent straight waveguides 121 through the bent waveguide 122.

[0022] Preferably, all the signal electrodes 21 are divided into two parts on both sides of the first Y-shaped waveguide structure 11. The multiple signal electrodes 21 of each part are arranged according to their distance from the first Y-shaped waveguide structure 11. Specifically, the multiple signal electrodes 21 of each part are the first signal electrode 21 to the j-th signal electrode 21, where j>1 and j is an odd number.

[0023] For the first signal electrode 21, the first end of the first signal electrode 21 is used to receive electrical signals, and the second end of the first signal electrode 21 is connected to the second signal electrode 21;

[0024] For the j-th signal electrode 21, the first end of the j-th signal electrode 21 is connected to the (j-1)-th signal electrode 21, and the second end of the j-th signal electrode 21 is used to output an electrical signal;

[0025] For the signal electrodes 21 other than the first signal electrode 21 and the jth signal electrode 21, the two ends of the signal electrode 21 are respectively connected to the two adjacent signal electrodes 21 through bent electrodes.

[0026] Preferably, all the ground electrodes 22 are divided into two parts on both sides of the first Y-shaped waveguide structure 11. The multiple ground electrodes 22 of each part are arranged according to their distance from the first Y-shaped waveguide structure 11. Specifically, the multiple ground electrodes 22 of each part are the first ground electrode 22 to the j-th ground electrode 22, where j>1 and j is an odd number.

[0027] Adjacent ground electrodes 22 are connected by connectors 6; and for a ground electrode 22 connected by two of the connectors 6, the two connectors 6 are distributed at both ends of the corresponding ground electrode 22.

[0028] Preferably, the lithium niobate layer 1 further includes a second Y-shaped waveguide structure 13, which is disposed opposite to the first Y-shaped waveguide structure 11. The second Y-shaped waveguide structure 13 includes a second main waveguide 131 and two second branch waveguides 132, wherein:

[0029] The second main waveguide 131 and the two second branch waveguides 132 are respectively connected;

[0030] One of the second branch waveguides 132 is connected to one of the outermost straight waveguides 121, and the other second branch waveguide 132 is connected to the other outermost straight waveguide 121.

[0031] Preferably, all of the signal electrodes 21 are specifically the first signal electrode 21 to the (2j-1)th signal electrode 21, where j > 1 and j is an odd number;

[0032] For the first signal electrode 21, the second end of the first signal electrode 21 is used for electrical signal input, and the first end of the first signal electrode 21 is connected to the second signal electrode 21;

[0033] For the 2j-1 signal electrode 21, the first end of the 2j-1 signal electrode 21 is used for electrical signal emission, and the second end of the 2j-1 signal electrode 21 is connected to the 2j-2 signal electrode 21;

[0034] For the signal electrodes 21 other than the first signal electrode 21 and the second (j-1)th signal electrode 21, the two ends of the signal electrode 21 are respectively connected to the two adjacent signal electrodes 21 through bent electrodes.

[0035] Preferably, all of the ground electrodes 22 are specifically the first ground electrode 22 to the second j ground electrode 22, where j > 1 and j is an odd number;

[0036] For the first ground electrode 22, the first end of the first ground electrode 22 and the second ground electrode 22 are connected by connector 6;

[0037] For the 2jth ground electrode 22, the first end of the 2jth ground electrode 22 and the 2j-1th ground electrode 22 are connected by a connector 6;

[0038] For the ground electrodes 22 other than the first ground electrode 22 and the second ground electrode 22, the two ends of the ground electrode 22 are respectively connected to two adjacent connectors 6 through connectors 6.

[0039] Secondly, a method for fabricating a Y-type thin-film lithium niobate electro-optic modulator is provided, applicable to the aforementioned Y-type thin-film lithium niobate electro-optic modulator, comprising:

[0040] The lithium niobate layer 1 is grown on the oxide layer 3, and the lithium niobate layer 1 is etched into a first Y-shaped waveguide structure 11 and two curved waveguide structures 12. The two curved waveguide structures 12 are symmetrically arranged on both sides of the first Y-shaped waveguide structure 11 and connected to the first Y-shaped waveguide structure 11. The curved waveguide structure 12 includes multiple straight waveguides 121 and multiple curved waveguides 122. The multiple straight waveguides 121 are arranged parallel to each other, and adjacent straight waveguides 121 are connected end to end through the curved waveguides 122 to connect all straight waveguides 121 in the same curved waveguide structure 12 in series.

[0041] An electrode 2 is disposed on the lithium niobate layer 1. The electrode 2 includes a signal electrode 21 and a ground electrode 22. The ground electrode 22 and the signal electrode 21 are respectively disposed on both sides of each straight waveguide 121. The signal electrode 21 and the ground electrode 22 are respectively disposed parallel to the straight waveguide 121, thereby ensuring that the electric field direction generated by the ground electrode 22 and the signal electrode 21 is perpendicular to the straight waveguide 121.

[0042] This invention provides a Y-type thin-film lithium niobate electro-optic modulator and its fabrication method. The lithium niobate layer on the electro-optic modulator chip is etched into a corresponding curved waveguide structure, and two curved waveguide structures are symmetrically arranged on both sides of the Y-type waveguide structure, ensuring that the height of the two optical paths is consistent. The curved waveguide structure reduces the space required by the waveguide while maintaining the waveguide length. For waveguides of the same length, a shorter chip can be used. Simultaneously, signal electrodes and ground electrodes are positioned on both sides of each straight waveguide segment in the curved waveguide structure to modulate the optical signal in the waveguide, thus fulfilling the modulation requirements of the electro-optic modulator. Attached Figure Description

[0043] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments of the present invention will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0044] Figure 1 This is a partial top view of a Y-type thin-film lithium niobate electro-optic modulator provided in an embodiment of the present invention;

[0045] Figure 2 This is a top view of the lithium niobate layer in a Y-type thin-film lithium niobate electro-optic modulator provided in an embodiment of the present invention;

[0046] Figure 3 This is a top view of the lithium niobate layer in another Y-type thin-film lithium niobate electro-optic modulator provided in an embodiment of the present invention;

[0047] Figure 4 This is a partial top view of another Y-type thin-film lithium niobate electro-optic modulator provided in an embodiment of the present invention;

[0048] Figure 5 This is a partial top view of a Y-type thin-film lithium niobate electro-optic modulator provided in an embodiment of the present invention;

[0049] Figure 6 This is a cross-sectional view of a Y-type thin-film lithium niobate electro-optic modulator provided in an embodiment of the present invention;

[0050] Figure 7This is a top view of the lithium niobate layer in a Y-type thin-film lithium niobate electro-optic modulator provided in an embodiment of the present invention;

[0051] Figure 8 This is a top view of the lithium niobate layer in another Y-type thin-film lithium niobate electro-optic modulator provided in an embodiment of the present invention;

[0052] Figure 9 This is a partial top view of another Y-type thin-film lithium niobate electro-optic modulator provided in an embodiment of the present invention;

[0053] Figure 10 This is a partial top view of the optical transmission path of a Y-type thin-film lithium niobate electro-optic modulator provided in an embodiment of the present invention;

[0054] Figure 11 This is a partial top view of another Y-type thin-film lithium niobate electro-optic modulator provided in an embodiment of the present invention;

[0055] Figure 12 This is a cross-sectional view of another Y-type thin-film lithium niobate electro-optic modulator provided in an embodiment of the present invention;

[0056] Figure 13 This is a cross-sectional view of another Y-type thin-film lithium niobate electro-optic modulator provided in an embodiment of the present invention;

[0057] Figure 14 This is a partial top view of a Y-type thin-film lithium niobate electro-optic modulator provided in an embodiment of the present invention;

[0058] Figure 15 This is a partial top view of a Y-type thin-film lithium niobate electro-optic modulator provided in an embodiment of the present invention;

[0059] Figure 16 This is a partial top view of the optical transmission path of a Y-type thin-film lithium niobate electro-optic modulator provided in an embodiment of the present invention;

[0060] Figure 17 This is a partial top view of the optical transmission path of another Y-type thin-film lithium niobate electro-optic modulator provided in an embodiment of the present invention;

[0061] Figure 18 This is a flowchart of a method for fabricating a Y-type thin-film lithium niobate electro-optic modulator according to an embodiment of the present invention;

[0062] The attached figures are labeled as follows:

[0063] 1. Lithium niobate layer; 11. First Y-type waveguide; 111. First main waveguide; 112. First branch waveguide; 12. Bending waveguide structure; 121. Straight waveguide; 122. Bending waveguide; 13. Second Y-type waveguide structure; 131. Second main waveguide; 132. Second branch waveguide; 2. Electrode; 21. Signal electrode; 22. Ground electrode; 3. Oxide layer; 4. Substrate; 5. Buffer layer; 6. Connector. Detailed Implementation

[0064] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0065] In the description of this invention, the terms "inner", "outer", "longitudinal", "lateral", "upper", "lower", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and do not require that this invention must be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0066] In this invention, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0067] In this application, unless otherwise expressly specified and limited, the term "connection" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a direct connection or an indirect connection through an intermediate medium. Furthermore, the term "coupled" can refer to an electrical connection that enables signal transmission.

[0068] Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0069] Example 1:

[0070] Embodiment 1 of the present invention provides a Y-type thin-film lithium niobate electro-optic modulator, such as... Figure 1 As shown, it includes: a lithium niobate layer 1, an electrode 2, and an oxide layer 3, wherein:

[0071] The lithium niobate layer 1 is disposed on the oxide layer 3; the lithium niobate layer 1 includes a first Y-shaped waveguide structure 11 and two curved waveguide structures 12, the two curved waveguide structures 12 are symmetrically disposed on both sides of the first Y-shaped waveguide structure 11 and connected to the first Y-shaped waveguide structure 11.

[0072] In this embodiment, a corresponding lithium niobate layer 1 is first grown on the oxide layer 3, and then the lithium niobate layer 1 is etched into a ridge waveguide to obtain the corresponding first Y-type waveguide structure 11 and two curved waveguide structures 12, as shown below. Figure 2 As shown, the first Y-shaped waveguide structure 11 is a Y-shaped waveguide structure on the left, while the curved waveguide structure 12 is symmetrically arranged on both sides of the first Y-shaped waveguide structure 11 and connected to the first Y-shaped waveguide structure 11. In this embodiment, the first Y-shaped waveguide structure 11 is used for inputting optical signals and transmitting the optical signals to the two curved waveguide structures 12 respectively through the first Y-shaped waveguide structure 11. The optical signals are transmitted outward through the two curved waveguide structures 12, ensuring that the height of the two optical paths is consistent. This is suitable for application scenarios such as integrated optical gyroscopes that require ensuring the height of the two optical paths to be consistent.

[0073] like Figure 3 As shown, the curved waveguide structure 12 includes multiple straight waveguides 121 and multiple curved waveguides 122. The multiple straight waveguides 121 are arranged in parallel to each other, and adjacent straight waveguides 121 are connected end to end through the curved waveguides 122 to connect all straight waveguides 121 in the same curved waveguide structure 12 together.

[0074] In this embodiment, the straight waveguide 121 is a waveguide section that is straight, and the curved waveguide 122 is a waveguide section that is curved. Multiple straight waveguides 121 are arranged in parallel array, and adjacent straight waveguides 121 are connected through the curved waveguides 122. While ensuring the length of the entire waveguide, the space occupied by the waveguide is reduced, and the chip length is avoided from needing to be increased.

[0075] like Figure 4 As shown, the electrode 2 is located on the lithium niobate layer 1. The electrode 2 includes a signal electrode 21 and a ground electrode 22. The ground electrode 22 and the signal electrode 21 are respectively disposed on both sides of each straight waveguide 121. The signal electrode 21 and the ground electrode 22 are respectively disposed parallel to the straight waveguide 121, thereby ensuring that the electric field direction generated by the ground electrode 22 and the signal electrode 21 is perpendicular to the straight waveguide 121.

[0076] The electrode 2 is grown on the etched lithium niobate layer 1 and oxide layer 3, and then etched accordingly to obtain a signal electrode 21 and a ground electrode 22. In this embodiment, a strip-shaped signal electrode 21 and a strip-shaped ground electrode 22 are respectively disposed on both sides of each straight waveguide 121. At the same time, the signal electrode 21 and the ground electrode 22 are parallel to the straight waveguide 121, and an electric field is formed between the signal electrode 21 and the ground electrode 22 on both sides of a straight waveguide 121. Figure 1 and Figure 4 The direction of the electric field is the direction of the black arrow. The electric field direction is perpendicular to the signal electrode 21 and the ground electrode 22, and therefore also perpendicular to the straight waveguide 121, thereby modulating the optical signal in the waveguide and ensuring that the electric field direction is consistent with the optical axis direction in the waveguide, thus realizing the modulation requirements of the electro-optic modulator.

[0077] like Figure 5 As shown, the large white arrow indicates the direction of optical signal propagation in the waveguide, and the black arrow indicates the direction of the electric field.

[0078] It is worth mentioning that in this embodiment, the straight waveguide 121 constitutes the majority of the curved waveguide structure 12, while the curved waveguide 122 constitutes a small portion. Therefore, in this embodiment, only the influence of the straight waveguide 121 needs to be considered for the propagation of the optical signal and electro-optic modulation, and the influence of the curved waveguide 122 can be ignored.

[0079] In this embodiment, the lithium niobate layer 1 on the electro-optic modulator chip is etched into a corresponding curved waveguide structure 12, and two curved waveguide structures 12 are symmetrically arranged on both sides of the optical signal inlet and outlet, ensuring that the height of the two optical paths is consistent. The curved waveguide structure 12 reduces the space required by the waveguide while ensuring the waveguide length, realizing the function of using a chip with a shorter length for the same waveguide length. At the same time, the signal electrode 21 and the ground electrode 22 are arranged on both sides of each straight waveguide 121 in the curved waveguide structure 12 to ensure that the electric field direction is consistent with the optical axis direction, thus realizing the modulation requirements of the electro-optic modulator.

[0080] In this embodiment, the Y-type thin-film lithium niobate electro-optic modulator provided, in addition to the lithium niobate layer 1, electrode 2, and oxide layer 3, requires other basic layers to realize the basic functions of the electro-optic modulator. Therefore, this embodiment also involves the following design:

[0081] like Figure 6 As shown, the Y-type thin-film lithium niobate electro-optic modulator further includes: a substrate 4 and a buffer layer 5, wherein:

[0082] The substrate 4 is located below the oxide layer 3; the buffer layer 5 is disposed between the lithium niobate layer 1 and the electrode 2.

[0083] In this embodiment, the substrate 4 can be a thin-film lithium niobate wafer substrate, and the material can be silicon, lithium niobate, or quartz.

[0084] The oxide layer 3 can be made of silica or benzocyclobutene, and the thickness of the oxide layer 3 can be from 0.5 μm to 20 μm.

[0085] The lithium niobate layer 1 can be made of X-tangential lithium niobate thin film material, and the waveguide thickness can be 600 nm. When etching the lithium niobate layer 1, the etching depth can be 300 nm. It should be noted that in this embodiment, the lithium niobate layer 1 can be made of materials such as silicon, silicon nitride, or lithium tantalate, in addition to lithium niobate.

[0086] The buffer pool material can be silica or total benzocyclobutene, and the thickness of the buffer pool can be 0.1µm-1µm.

[0087] The electrode 2 can be made of gold, copper or tungsten, and is not limited to elemental metals.

[0088] In this embodiment, the first Y-shaped waveguide structure 11 serves as the input port for the input optical signal. It also needs to transmit the optical signal to the two curved waveguide structures 12 on both sides, allowing the optical signal to be transmitted throughout the entire waveguide structure. Therefore, this embodiment also involves the following design:

[0089] like Figure 7 As shown, the first Y-shaped waveguide structure 11 includes a first main waveguide 111 and two first branch waveguides 112, wherein:

[0090] The first main waveguide 111 and the two first branch waveguides 112 are respectively connected; one of the first branch waveguides 112 is connected to one of the curved waveguide structures 12, and the other first branch waveguide 112 is connected to the other curved waveguide structure 12.

[0091] In this embodiment, the first main waveguide 111 serves as the input port for optical signals. Both first branch waveguides 112 are connected to the first main waveguide 111. The input optical signal is simultaneously transmitted through the two first branch waveguides 112 to the curved waveguide structures 12 on both sides, achieving simultaneous transmission of two optical paths and consistent optical path height. After the optical signal is transmitted to the curved waveguide structures 12 on both sides of the first Y-shaped waveguide structure 11, it is output from the outermost straight waveguide 121 of the two curved waveguide structures 12.

[0092] In addition, the first Y-shaped waveguide structure 11 can also serve as an output port for optical signal transmission. That is, the optical signal is input from the outermost straight waveguide 121 of the two curved waveguide structures 12, and after being transmitted in the curved waveguide structure 12, it is input from the two first branch waveguides 112 respectively, and output from the first main waveguide 111.

[0093] In this embodiment, in order to reduce the space occupied by the waveguide while ensuring the waveguide length, thereby further reducing the chip size, the specific bending distribution of the waveguide is as follows:

[0094] like Figure 8 As shown, the adjacent straight waveguides 121 are connected end-to-end through the curved waveguide 122 to connect all the straight waveguides 121 in the same curved waveguide structure 12 together, specifically including:

[0095] Each of the curved waveguide structures 12 includes a plurality of straight waveguides 121, arranged in ascending order of distance between the straight waveguides 121 and the first Y-shaped waveguide structure 11. Specifically, each of the curved waveguide structures 12 includes the first straight waveguide 121 to the j-th straight waveguide 121, where j > 1 and j is an odd number.

[0096] like Figure 8 As shown, in this embodiment, since the arrangement and connection of the straight waveguides 121 on both sides of the first Y-shaped waveguide structure 11 are symmetrical, this embodiment only describes the straight waveguide 121 on one side of the first Y-shaped waveguide structure 11, and the straight waveguide 121 on the other side can be described by referring to the description of that side; in this embodiment, the distances of the first straight waveguide 121 to the j-th straight waveguide 121 relative to the first Y-shaped waveguide structure 11 gradually increase; it should be noted that, Figure 8 Only three straight waveguides 121 are drawn on one side of the first Y-shaped waveguide structure 11, which is only one of the implementable examples and does not limit the number of straight waveguides 121 in other scenarios.

[0097] It should be noted that, since the two outermost straight waveguides 121 in the two curved waveguide structures 12 are needed for optical signal output, the two outermost straight waveguides 121 can only face the opposite end to the first Y-type waveguide structure 11, i.e. Figure 8 At the right end of the diagram, it can be seen that if the sequence number of the outermost straight waveguide 121 is even, then the straight waveguide 121 will face... Figure 8 The left end of the structure does not meet the requirements. Therefore, the sequence number of the outermost straight waveguide 121 should be an odd number other than 1. Thus, the number of straight waveguides 121 in the curved waveguide structure 12 should be an odd number. Figure 8 As shown, one arrangement and connection method is provided for this scenario.

[0098] like Figure 8 As shown, for the first straight waveguide 121, the first end of the first straight waveguide 121 is connected to the first Y-shaped waveguide structure 11, and the second end of the first straight waveguide 121 is connected to the second straight waveguide 121 through a bent waveguide 122.

[0099] like Figure 8 As shown, for the j-th straight waveguide 121, the first end of the j-th straight waveguide 121 is connected to the (j-1)-th straight waveguide 121 through a bent waveguide 122; the second end of the j-th straight waveguide 121 is used for outputting optical signals.

[0100] For the straight waveguides 121 other than the first and j-th straight waveguides 121, both ends of each straight waveguide 121 are connected to two adjacent straight waveguides 121 via bent waveguides 122. The specific connection method is as follows:

[0101] For the i-th straight waveguide 121, where i is a positive integer, 1 < i < j, i increases progressively according to the distance of the straight waveguide 121 relative to the first Y-type waveguide structure 11, specifically including:

[0102] like Figure 8 As shown, when i is an odd number, the first end of the i-th straight waveguide 121 is connected to the (i-1)-th straight waveguide 121 through a bent waveguide 122, and the second end of the i-th straight waveguide 121 is connected to the (i+1)-th straight waveguide 121 through a bent waveguide 122.

[0103] like Figure 8 As shown, when i is an even number, the first end of the i-th straight waveguide 121 and the (i+1)-th straight waveguide 121 are connected through a bent waveguide 122, and the second end of the i-th straight waveguide 121 and the (i-1)-th straight waveguide 121 are connected through a bent waveguide 122.

[0104] like Figure 8 As shown, in this embodiment, the first end faces the side where the first Y-shaped waveguide structure 11 is located, and the second end faces the relative position of the first Y-shaped waveguide structure 11.

[0105] Through the above connection method, the two curved waveguide structures 12 are arranged in a curved configuration to achieve the transmission of corresponding optical signals, such as... Figure 10 As shown, the large white arrow represents the transmission path of the optical signal in the curved waveguide structure 12 when the optical signal is input from the first Y-type waveguide structure 11.

[0106] Furthermore, to achieve high bandwidth modulation performance, this embodiment also requires the signal electrode 21 and ground electrode 22 to be distributed accordingly, ensuring that the electrical signal transmission direction and optical signal transmission direction in the signal electrode 21 are consistent, so as to achieve the consistency between the microwave phase velocity and the optical group velocity, thereby achieving high bandwidth modulation performance. Therefore, this embodiment also provides a preferred solution:

[0107] The lithium niobate layer 1 is disposed on the oxide layer 3. The lithium niobate layer 1 includes a first Y-shaped waveguide structure 11 and two curved waveguide structures 12. The two curved waveguide structures 12 are symmetrically disposed on both sides of the first Y-shaped waveguide structure 11 and connected to the first Y-shaped waveguide structure 11. The curved waveguide structure 12 includes multiple straight waveguides 121 and multiple curved waveguides 122. The multiple straight waveguides 121 are arranged parallel to each other, and adjacent straight waveguides 121 are connected end to end through the curved waveguides 122 to connect all straight waveguides 121 in the same curved waveguide structure 12. The signal electrode 21 is located on the lithium niobate layer 1. The signal electrode 21 is disposed on one side of each straight waveguide 121, and the path direction of all the signal electrodes 21 is consistent with the directional path of the curved waveguide structure 12, ensuring that the electrical signal flow direction in the signal electrode 21 is consistent with the optical signal flow direction in the curved waveguide structure 12.

[0108] like Figure 9 As shown, all the signal electrodes 21 are divided into two parts on both sides of the first Y-shaped waveguide structure 11. The multiple signal electrodes 21 in each part are arranged in ascending order of distance from the first Y-shaped waveguide structure 11. Specifically, the multiple signal electrodes 21 in each part are the first signal electrode 21 to the j-th signal electrode 21, where j > 1 and j is an odd number. Here, j is equal to the number of straight waveguides 121 contained in the curved waveguide structure 12.

[0109] In this embodiment, since each straight waveguide 121 in the two curved waveguide structures 12 has a signal electrode 21 and a ground electrode 22 on both sides, all the signal electrodes 21 are also symmetrically distributed with respect to both sides of the first Y-shaped waveguide structure 11, consistent with the arrangement of the straight waveguides 121. Therefore, in this embodiment, only the signal electrode 21 on any one side of the first Y-shaped waveguide structure 11 is described, and the signal electrode 21 on the other side can be described with reference to that side. In this embodiment, the distance between the first signal electrode 21 to the j-th signal electrode 21 and the first Y-shaped waveguide structure 11 gradually increases. It should be noted that... Figure 9 Only three signal electrodes 21 are shown on one side of the first Y-shaped waveguide structure 11, which is only one of the possible implementation examples and does not limit the number of signal electrodes 21 in other scenarios.

[0110] It should be noted that in this embodiment, the single signal electrode 21 refers to... Figure 9 The individual signal electrode 21 in this embodiment refers only to the strip-shaped signal electrode 21, since the bent and connected electrode portions do not affect the electro-optic modulation.

[0111] like Figure 9 As shown, for the first signal electrode 21, the first end of the first signal electrode 21 is used to receive electrical signals, and the second end of the first signal electrode 21 is connected to the second signal electrode 21.

[0112] For the j-th signal electrode 21, the first end of the j-th signal electrode 21 is connected to the (j-1)-th signal electrode 21; the second end of the j-th signal electrode 21 is used to output an electrical signal.

[0113] For the signal electrodes 21 other than the first signal electrode 21 and the j-th signal electrode 21, each signal electrode 21 has its two ends connected to two adjacent signal electrodes 21 via bent electrodes. The specific connection method is as follows:

[0114] For the i-th signal electrode 21, where i is a positive integer, 1 < i < j, i increases progressively according to the distance of the signal electrode 21 relative to the first Y-type waveguide structure 11, specifically including:

[0115] When i is an odd number, the first end of the i-th signal electrode 21 is connected to the (i-1)-th signal electrode 21, and the second end of the i-th signal electrode 21 is connected to the (i+1)-th signal electrode 21.

[0116] When i is an even number, the first end of the i-th signal electrode 21 is connected to the (i+1)-th signal electrode 21, and the second end of the i-th signal electrode 21 is connected to the (i-1)-th signal electrode 21.

[0117] like Figure 9 As shown, it should be noted that when different signal electrodes 21 are connected, they can be connected by bending or by a vertical corner; if the signal electrodes 21 are arranged in the above manner, the electrical signal enters from the first end of the first signal electrode 21, as shown. Figure 10 As shown, Figure 10 The long black arrows in the diagram represent the transmission path of the electrical signal in the signal electrode 21, and the final electrical signal is output from the two outermost signal electrodes 21. This ensures that the optical signal and the radio frequency signal (i.e., the electrical signal) propagate in the same direction.

[0118] In this embodiment, the ground electrode 22 also needs to be arranged in conjunction with the signal electrode 21 to generate a corresponding electric field. Therefore, this embodiment also involves the following design:

[0119] like Figure 11 As shown, all the ground electrodes 22 are divided into two parts on both sides of the first Y-shaped waveguide structure 11. The multiple ground electrodes 22 in each part are arranged from small to large according to their distance from the first Y-shaped waveguide structure 11. Specifically, the multiple ground electrodes 22 in each part are the first ground electrode 22 to the j-th ground electrode 22, where j>1 and j is an odd number.

[0120] In this embodiment, since each straight waveguide 121 in the two curved waveguide structures 12 has a signal electrode 21 and a ground electrode 22 on both sides, all the ground electrodes 22 are symmetrically distributed with respect to both sides of the first Y-shaped waveguide structure 11, consistent with the arrangement of the straight waveguides 121. Therefore, in this embodiment, only the ground electrode 22 on one side of the first Y-shaped waveguide structure 11 is described, and the ground electrode 22 on the other side can be described by referring to the description of that side. In this embodiment, the distance between the first ground electrode 22 to the j-th ground electrode 22 and the first Y-shaped waveguide structure 11 gradually increases. It should be noted that... Figure 11 Only three ground electrodes 22 are drawn on one side of the first Y-shaped waveguide structure 11, which is only one of the possible implementation examples and does not limit the number of ground electrodes 22 in other scenarios.

[0121] Adjacent ground electrodes 22 are connected by connectors 6; and for a ground electrode 22 connected by two connectors 6, the two connectors 6 are distributed at both ends of the corresponding ground electrode 22. The specific connection method is as follows:

[0122] like Figure 11 As shown, for the first ground electrode 22, the second end of the first ground electrode 22 and the second ground electrode 22 are connected by connector 6.

[0123] For the j-th ground electrode 22, the first end of the j-th ground electrode 22 and the (j-1)-th ground electrode 22 are connected by a connector 6.

[0124] For the i-th ground electrode 22, where i is a positive integer, 1 < i < j, i increases progressively according to the distance of the ground electrode 22 relative to the first Y-type waveguide structure 11, specifically including:

[0125] When i is an odd number, the first end of the i-th ground electrode 22 and the (i-1)-th ground electrode 22 are connected through connector 6, and the second end of the i-th ground electrode 22 and the (i+1)-th ground electrode 22 are connected through connector 6.

[0126] When i is an even number, the first end of the i-th ground electrode 22 and the (i+1)-th ground electrode 22 are connected by connector 6, and the second end of the i-th ground electrode 22 and the (i-1)-th ground electrode 22 are connected by connector 6.

[0127] like Figures 11-13 As shown, it should be noted that in this embodiment, each ground electrode 22 is strip-shaped, and the connector 6 can be connected by methods such as gold wire bonding, metal bridging, or flip-chip bonding. Figure 12 and Figure 13 As shown, the connector 6 is connected from above the signal electrode 21 to prevent the signal electrode 21 from being short-circuited with the ground electrode 22.

[0128] Example 2:

[0129] Based on Embodiment 1, Embodiment 2 of the present invention provides another Y-type thin-film lithium niobate electro-optic modulator. This modulator is primarily used as a Mach-Zehnder interferometer modulation structure. Specifically, based on Embodiment 1, a waveguide structure is positioned opposite the first Y-type waveguide structure 11. Optical signals are input through this waveguide structure, while the original first Y-type waveguide structure 11 is used for optical signal output. The structure is as follows:

[0130] like Figure 14 and Figure 15 As shown, the lithium niobate layer 1 further includes a second Y-type waveguide structure 13, which is disposed opposite to the first Y-type waveguide structure 11. The second Y-type waveguide structure 13 includes a second main waveguide 131 and two second branch waveguides 132, wherein:

[0131] The second main waveguide 131 is connected to two second branch waveguides 132 respectively; one of the second branch waveguides 132 is connected to one of the outermost straight waveguides 121, and the other second branch waveguide 132 is connected to the other outermost straight waveguide 121.

[0132] like Figure 14 and Figure 15 As shown, in this embodiment, optical signals can be input through the second Y-shaped waveguide structure 13. After passing through the two curved waveguide structures 12, the optical signals flow to the first Y-shaped waveguide structure 11 and are output through the first Y-shaped waveguide structure 11.

[0133] Compared to Embodiment 1, in this embodiment, due to the change in the direction of the optical signal, the signal electrode 21 and the ground electrode 22 need to be redesigned. After ensuring that the signal electrode 21 and the ground electrode 22 are arranged in parallel on both sides of each straight waveguide 121, the different signal electrodes 21 need to be connected to each other, and the propagation direction of the electrical signal in the signal electrode 21 and the optical signal in the waveguide need to be consistent. Therefore, this embodiment also involves the following design:

[0134] like Figure 16 As shown, all of the signal electrodes 21 are specifically the first signal electrode 21 to the second (j-1)th signal electrode 21, where j > 1 and j is an odd number.

[0135] In this embodiment, since the optical signal is transmitted from the waveguides on both sides to the waveguide in the middle, all signal electrodes 21 are connected in series, and it is necessary to ensure that the direction of electrical signal transmission is consistent with the direction of optical signal transmission to achieve high bandwidth modulation performance. Figure 16 As shown, in this embodiment, j is the number of straight waveguides 121 on any side of the first Y-shaped waveguide structure 11 in Embodiment 1. Since all signal electrodes 21 are connected in series in this embodiment, in order to ensure the consistency between the electrical signal transmission direction and the optical signal transmission direction, the number of signal electrodes 21 in this embodiment is 2j-1. The first signal electrode 21 to the second j-1 signal electrode 21 is the arrangement order of all signal electrodes 21.

[0136] like Figure 16 As shown, for the first signal electrode 21, the second end of the first signal electrode 21 is used for electrical signal input, and the first end of the first signal electrode 21 is connected to the second signal electrode 21.

[0137] For the 2j-1 signal electrode 21, the first end of the 2j-1 signal electrode 21 is used for electrical signal transmission, and the second end of the 2j-1 signal electrode 21 is connected to the 2j-2 signal electrode 21.

[0138] For the signal electrodes 21 other than the first signal electrode 21 and the (2j-1)th signal electrode 21, each signal electrode 21 has its two ends connected to two adjacent signal electrodes 21 via bent electrodes. The specific connection method is as follows:

[0139] For the h-th signal electrode 21, where h is a positive integer, 1 < h < 2j-1, h increases progressively according to the arrangement order of all the signal electrodes 21, specifically including:

[0140] When h is an odd number, the first end of the h-th signal electrode 21 is connected to the (h+1)-th signal electrode 21, and the second end of the h-th signal electrode 21 is connected to the (h-1)-th signal electrode 21.

[0141] When h is an even number, the first end of the h-th signal electrode 21 is connected to the (h-1)-th signal electrode 21, and the second end of the h-th signal electrode 21 is connected to the (h+1)-th signal electrode 21.

[0142] like Figure 16 As shown, by arranging the signal electrodes 21 in the manner described above, it can be ensured that the transmission direction of the optical signal in each straight waveguide 121 is consistent with the transmission direction of the electrical signal in its corresponding signal electrode 21. Figure 16 The electrical signal is input from the second end of the uppermost signal electrode 21. The direction of the thick black arrow in the diagram indicates the direction of signal transmission. The electrical signal is ultimately output from the first end of the lowermost signal electrode 21. Figure 16 As can be seen, the transmission direction of the electrical signal in the signal electrode 21 is consistent with the transmission direction of the optical signal in the waveguide at the corresponding position, thus achieving high bandwidth modulation performance under the Mach-Zehnder interferometer modulation structure.

[0143] In this embodiment, the ground electrode 22 also needs to be arranged in the same way as the signal electrode 21. Therefore, this embodiment also involves the following design:

[0144] like Figure 17 As shown, all the ground electrodes 22 specifically include the first ground electrode 22 to the second j ground electrode 22, where j > 1 and j is an odd number.

[0145] In this embodiment, in order to ensure that the direction of electrical signal transmission and the direction of optical signal transmission are consistent, the number of ground electrodes 22 is 2j, and the first ground electrode 22 to the second j ground electrodes 22 are arranged in the order of all ground electrodes 22.

[0146] like Figure 17 As shown, for the first ground electrode 22, the first end of the first ground electrode 22 and the second ground electrode 22 are connected by connector 6.

[0147] For the 2jth ground electrode 22, the first end of the 2jth ground electrode 22 and the 2j-1th ground electrode 22 are connected by a connector 6.

[0148] For the ground electrodes 22 other than the first ground electrode 22 and the second j-th ground electrode 22, each of the two ends of the ground electrode 22 is connected to two adjacent connectors 6 via connectors 6. The specific connection method is as follows:

[0149] For the k-th ground electrode 22, where k is a positive integer, 1 < k < 2j, k increases progressively according to the arrangement order of all the ground electrodes 22, specifically including:

[0150] When k is an odd number, the first end of the kth ground electrode 22 and the (k+1)th ground electrode 22 are connected through connector 6, and the second end of the kth ground electrode 22 and the (k-1)th ground electrode 22 are connected through connector 6.

[0151] When k is an even number, the first end of the kth ground electrode 22 and the (k-1)th ground electrode 22 are connected through connector 6, and the second end of the kth ground electrode 22 and the (k+1)th ground electrode 22 are connected through connector 6.

[0152] like Figure 17 As shown, in this embodiment, each ground electrode 22 is strip-shaped, and the connector 6 can be connected using gold wire bonding, metal bridging, or flip-chip soldering. Figure 12 and Figure 13 As shown, the connector 6 is connected from above the signal electrode 21 to prevent the signal electrode 21 from being short-circuited with the ground electrode 22.

[0153] Example 3:

[0154] Based on Examples 1 and 2, Embodiment 3 of the present invention provides a method for fabricating a Y-type thin-film lithium niobate electro-optic modulator, which is applied to the Y-type thin-film lithium niobate electro-optic modulators in Examples 1 and 2. Figure 18 As shown, the method flow includes:

[0155] In step 101, the lithium niobate layer 1 is grown on the oxide layer 3, and the lithium niobate layer 1 is etched into a first Y-shaped waveguide structure 11 and two curved waveguide structures 12.

[0156] Two curved waveguide structures 12 are symmetrically arranged on both sides of the first Y-shaped waveguide structure 11 and connected to the first Y-shaped waveguide structure 11. The curved waveguide structure 12 includes multiple straight waveguides 121 and multiple curved waveguides 122. The multiple straight waveguides 121 are arranged parallel to each other, and adjacent straight waveguides 121 are connected end to end through the curved waveguides 122 to connect all straight waveguides 121 in the same curved waveguide structure 12 together.

[0157] In step 102, an electrode 2 is disposed on the lithium niobate layer 1. The electrode 2 includes a signal electrode 21 and a ground electrode 22. The ground electrode 22 and the signal electrode 21 are disposed on both sides of each straight waveguide 121. The signal electrode 21 and the ground electrode 22 are disposed parallel to the straight waveguide 121, thereby ensuring that the electric field direction generated by the ground electrode 22 and the signal electrode 21 is perpendicular to the straight waveguide 121.

[0158] For the specific structure of the Y-type thin-film lithium niobate electro-optic modulator, please refer to the aforementioned embodiments, and it will not be repeated here.

[0159] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A Y-type thin-film lithium niobate electro-optic modulator, characterized in that, include: The lithium niobate layer (1), the electrode (2), and the oxide layer (3) are as follows: The lithium niobate layer (1) is disposed on the oxide layer (3); The lithium niobate layer (1) includes a first Y-shaped waveguide structure (11) and two curved waveguide structures (12). The two curved waveguide structures (12) are symmetrically arranged on both sides of the first Y-shaped waveguide structure (11) and connected to the first Y-shaped waveguide structure (11). The curved waveguide structure (12) includes multiple straight waveguides (121) and multiple curved waveguides (122). The multiple straight waveguides (121) are arranged in parallel to each other, and adjacent straight waveguides (121) are connected end to end through the curved waveguides (122) to connect all the straight waveguides (121) in the same curved waveguide structure (12) together. The electrode (2) is located on the lithium niobate layer (1). The electrode (2) includes a signal electrode (21) and a ground electrode (22). The ground electrode (22) and the signal electrode (21) are respectively arranged on both sides of each straight waveguide (121). The signal electrode (21) and the ground electrode (22) are arranged parallel to the straight waveguide (121) to ensure that the electric field direction generated by the ground electrode (22) and the signal electrode (21) is perpendicular to the straight waveguide (121). All the signal electrodes (21) are divided into two parts on both sides of the first Y-shaped waveguide structure (11). The multiple signal electrodes (21) of each part are arranged according to their distance from the first Y-shaped waveguide structure (11). Specifically, the multiple signal electrodes (21) of each part are the first signal electrode (21) to the j-th signal electrode (21), where j > 1 and j is an odd number. For the first signal electrode (21), the first end of the first signal electrode (21) is used to receive electrical signals. The second end is connected to the second signal electrode (21); for the j-th signal electrode (21), the first end of the j-th signal electrode (21) is connected to the (j-1)-th signal electrode (21), and the second end of the j-th signal electrode (21) is used to output an electrical signal; for the signal electrodes (21) other than the first signal electrode (21) and the j-th signal electrode (21), the two ends of the signal electrode (21) are respectively connected to the two adjacent signal electrodes (21) through bent electrodes; For the i-th signal electrode (21), where i is a positive integer, 1 < i < j, i increases gradually according to the distance of the signal electrode (21) relative to the first Y-type waveguide structure (11), specifically including: when i is odd, the first end of the i-th signal electrode (21) is connected to the (i-1)-th signal electrode (21), and the second end of the i-th signal electrode (21) is connected to the (i+1)-th signal electrode (21); when i is even, the first end of the i-th signal electrode (21) is connected to the (i+1)-th signal electrode (21), and the second end of the i-th signal electrode (21) is connected to the (i-1)-th signal electrode (21); Each ground electrode (22) is strip-shaped; all the ground electrodes (22) are divided into two parts on both sides of the first Y-shaped waveguide structure (11), and the multiple ground electrodes (22) of each part are arranged according to the distance relative to the first Y-shaped waveguide structure (11). Specifically, the multiple ground electrodes (22) of each part are the first ground electrode (22) to the j-th ground electrode (22), where j>1 and j is an odd number; adjacent ground electrodes (22) are connected by connectors (6); and for a ground electrode (22) connected by two connectors (6), the two connectors (6) are distributed at both ends of the corresponding ground electrode (22).

2. The Y-type thin-film lithium niobate electro-optic modulator according to claim 1, characterized in that, The Y-type thin-film lithium niobate electro-optic modulator further includes: a substrate (4) and a buffer layer (5), wherein: The substrate (4) is located below the oxide layer (3); The buffer layer (5) is disposed between the lithium niobate layer (1) and the electrode (2).

3. The Y-type thin-film lithium niobate electro-optic modulator according to claim 1, characterized in that, The first Y-shaped waveguide structure (11) includes a first main waveguide (111) and two first branch waveguides (112), wherein: The first main waveguide (111) and the two first branch waveguides (112) are connected to each other; One of the first branch waveguides (112) is connected to one of the curved waveguide structures (12), and the other first branch waveguide (112) is connected to the other curved waveguide structure (12).

4. The Y-type thin-film lithium niobate electro-optic modulator according to claim 1, characterized in that, The adjacent straight waveguides (121) are connected end-to-end through the curved waveguide (122) to connect all the straight waveguides (121) in the same curved waveguide structure (12) together, specifically including: Each of the curved waveguide structures (12) includes a plurality of straight waveguides (121). According to the distance of the straight waveguides (121) relative to the first Y-type waveguide structure (11), each of the curved waveguide structures (12) specifically includes the first straight waveguide (121) to the j-th straight waveguide (121), where j>1 and j is an odd number. For the first straight waveguide (121), the first end of the first straight waveguide (121) is connected to the first Y-type waveguide structure (11), and the second end of the first straight waveguide (121) is connected to the second straight waveguide (121) through a bent waveguide (122); For the j-th straight waveguide (121), the first end of the j-th straight waveguide (121) and the (j-1)-th straight waveguide (121) are connected through a bent waveguide (122), and the second end of the j-th straight waveguide (121) is used for outputting optical signals; For the straight waveguides (121) other than the first straight waveguide (121) and the jth straight waveguide (121), the two ends of the straight waveguide (121) are respectively connected to the two adjacent straight waveguides (121) through the bent waveguides (122).

5. A Y-type thin-film lithium niobate electro-optic modulator, comprising: The lithium niobate layer (1), electrode (2), and oxide layer (3) are provided, wherein: the lithium niobate layer (1) is disposed on the oxide layer (3); the lithium niobate layer (1) includes a first Y-type waveguide structure (11) and two curved waveguide structures (12), the two curved waveguide structures (12) are symmetrically disposed on both sides of the first Y-type waveguide structure (11) and connected to the first Y-type waveguide structure (11); the curved waveguide structure (12) includes multiple straight waveguides (121) and multiple curved waveguides (122), the multiple straight waveguides (121) are arranged parallel to each other, and adjacent straight waveguides (121) are connected by... The curved waveguides (122) are connected end to end to connect all the straight waveguides (121) in the same curved waveguide structure (12) together; the electrode (2) is located on the lithium niobate layer (1), and the electrode (2) includes a signal electrode (21) and a ground electrode (22). The ground electrode (22) and the signal electrode (21) are respectively provided on both sides of each straight waveguide (121). The signal electrode (21) and the ground electrode (22) are respectively arranged parallel to the straight waveguide (121) to ensure that the electric field direction generated by the ground electrode (22) and the signal electrode (21) is perpendicular to the straight waveguide (121); The lithium niobate layer (1) further includes a second Y-type waveguide structure (13), which is arranged opposite to the first Y-type waveguide structure (11). The second Y-type waveguide structure (13) includes a second main waveguide (131) and two second branch waveguides (132), wherein: the second main waveguide (131) and the two second branch waveguides (132) are respectively connected; one of the second branch waveguides (132) is connected to one of the outermost straight waveguides (121), and the other second branch waveguide (132) is connected to the other outermost straight waveguide (121); All of the signal electrodes (21) are specifically the first signal electrode (21) to the (2j-1)th signal electrode (21), where j > 1 and j is an odd number; for the first signal electrode (21), the second end of the first signal electrode (21) is used for electrical signal input, and the first end of the first signal electrode (21) is connected to the second signal electrode (21); for the (2j-1)th signal electrode (21), the first end of the (2j-1)th signal electrode (21) is used for electrical signal output, and the second end of the (2j-1)th signal electrode (21) is connected to the (2j-2)th signal electrode (21); for the signal electrodes (21) other than the first signal electrode (21) and the (2j-1)th signal electrode (21), the two ends of the signal electrode (21) are respectively connected to the two adjacent signal electrodes (21) through bent electrodes; Each ground electrode 22 is strip-shaped; all the ground electrodes (22) are specifically the first ground electrode (22) to the second j ground electrode (22), where j > 1 and j is an odd number; for the first ground electrode (22), the first end of the first ground electrode (22) and the second ground electrode (22) are connected by a connector (6); for the second j ground electrode (22), the first end of the second j ground electrode (22) and the second j-1 ground electrode (22) are connected by a connector (6); for the ground electrodes (22) other than the first ground electrode (22) and the second j ground electrode (22), the two ends of the ground electrode (22) are respectively connected to two adjacent connectors (6) through connectors (6).

6. A method for fabricating a Y-type thin-film lithium niobate electro-optic modulator, applied to the Y-type thin-film lithium niobate electro-optic modulator as described in any one of claims 1-5, characterized in that, include: The lithium niobate layer (1) is grown on the oxide layer (3), and the lithium niobate layer (1) is etched into a first Y-shaped waveguide structure (11) and two curved waveguide structures (12). The two curved waveguide structures (12) are symmetrically arranged on both sides of the first Y-shaped waveguide structure (11) and connected to the first Y-shaped waveguide structure (11). The curved waveguide structure (12) includes multiple straight waveguides (121) and multiple curved waveguides (122). The multiple straight waveguides (121) are arranged in parallel with each other, and adjacent straight waveguides (121) are connected end to end through the curved waveguides (122) to connect all straight waveguides (121) in the same curved waveguide structure (12) together. An electrode (2) is disposed on the lithium niobate layer (1). The electrode (2) includes a signal electrode (21) and a ground electrode (22). The ground electrode (22) and the signal electrode (21) are respectively disposed on both sides of each straight waveguide (121). The signal electrode (21) and the ground electrode (22) are respectively disposed parallel to the straight waveguide (121), thereby ensuring that the electric field direction generated by the ground electrode (22) and the signal electrode (21) is perpendicular to the straight waveguide (121).

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