An ultra-small, high-bandwidth, single-ended, thin-film lithium niobate electro-optic modulator

Abstract

The present invention relates to an ultra-small, high-bandwidth, single-ended, thin-film lithium niobate electro-optical modulator, comprising an SSMP radio frequency (RF) component, a high-frequency transition film substrate, an electro-optical modulator chip, a dual-core fiber optic (FA), a terminal-matching film substrate, an input optical fiber, an output optical fiber, and a packaging shell. The thin-film lithium niobate electro-optical modulator chip waveguide of the present invention exhibits a "U"-shaped structure, with the waveguide input and output ports located on the same side of the chip. A dual-core fiber optic (FA) is used to align the waveguide input and output ports for coupling, reducing the space required for coupling and improving coupling convenience. A mode field conversion structure is designed on the dual-core fiber optic (FA) to reduce the size of the fiber's mode spot. An SSC mode spot converter structure is designed on the chip waveguide to amplify the waveguide's mode spot, converting the fiber's mode spot size to the same size as the waveguide's mode spot, achieving efficient, low-loss coupling. The RF feed port, optical input and output ports, and DC pins are located on opposite sides of the device, facilitating dense array arrangement of user terminals and enabling compact system integration.

Description

Technical Field

[0001] The present invention relates to the field of microwave photon transmission, and in particular to an ultra-small, high-bandwidth, single-ended fiber-outlet thin-film lithium niobate electro-optic modulator. Background Art

[0002] Compared to traditional electrical transmission technologies, microwave photonic transmission links offer significant advantages, including high bandwidth, low loss, light weight, and strong resistance to electromagnetic interference, making them widely used in the communications field. As a core optoelectronic component in microwave photonic transmission links, electro-optical modulators (EOMs) convert electrical signals into optical signals.

[0003] Currently, conventional bulk lithium niobate electro-optical modulators (EOMs) are commonly used in microwave photonic transmission links to achieve these functions. However, due to limitations in bulk lithium niobate material properties and chip design, these EOMs suffer from high half-wave voltage, low bandwidth, large size, and heavy weight, hindering their further application and development.

[0004] Thin-film lithium niobate electro-optic modulator chips can be developed based on the emerging lithium niobate thin film material in recent years. Because it greatly reduces the distance between the chip electrode and the waveguide, it significantly improves the intensity of the electro-optic effect, making the thin-film lithium niobate electro-optic modulator have a lower half-wave voltage, higher bandwidth, smaller size and lighter weight, which is an important development trend of electro-optic modulators in the future.

[0005] There is an urgent need to realize an ultra-small, high-bandwidth, single-ended fiber-optic thin-film lithium niobate electro-optic modulator in order to solve the shortcomings of traditional bulk lithium niobate electro-optic modulators and promote the development of lithium niobate thin-film electro-optic modulator technology. Summary of the Invention

[0006] In order to solve the problems of high half-wave voltage, low bandwidth and large size of traditional bulk lithium niobate electro-optic modulator, the purpose of the present invention is to provide an ultra-small, high-bandwidth, single-ended thin-film lithium niobate electro-optic modulator.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] An ultra-small, high-bandwidth, single-ended fiber-outlet thin-film lithium niobate electro-optical modulator comprises: an SSMP radio frequency component, a high-frequency transition thin-film substrate, an electro-optical modulator chip, a dual-core FA, a terminal matching thin-film substrate, an input optical fiber, an output optical fiber, and a packaging shell.

[0009] The SSMP radio frequency component is mounted on the packaging shell and is used for feeding radio frequency signals.

[0010] The high-frequency transition film substrate is arranged between the SSMP radio frequency component and the electro-optic modulator chip to achieve impedance matching.

[0011] The electro-optic modulator chip adopts a waveguide folded thin film lithium niobate electro-optic modulator chip, which is used to modulate optical signals and includes a radio frequency electrode, a waveguide structure, an MPD electrode and a thermal modulation electrode.

[0012] The dual-core FA is used to couple the optical signal of the input optical fiber to the waveguide structure of the electro-optical modulator chip, and couple the optical signal from the waveguide structure of the electro-optical modulator chip back to the output optical fiber at the output end.

[0013] The terminal matching thin film substrate is used to achieve terminal impedance matching of the output electrode of the electro-optic modulator chip, and is connected to the thermal adjustment electrode of the electro-optic modulator chip to control the operating point of the electro-optic modulator chip by loading an external DC signal. It is also connected to the MPD electrode of the electro-optic modulator chip to draw out the MPD current.

[0014] Furthermore, the electro-optic modulator chip adopts a waveguide folded thin film lithium niobate electro-optic modulator chip, and the waveguide structure on the electro-optic modulator chip is a U-shaped waveguide; the waveguide input port and the waveguide output port of the U-shaped waveguide are located on the same side of the electro-optic modulator chip, and a radio frequency feed port is provided on the other side of the electro-optic modulator chip; the radio frequency feed port is used to feed an external radio frequency signal into the electro-optic modulator chip for electro-optical modulation.

[0015] Furthermore, the packaging shell is provided with a DC pin on the same side as the optical input and output ports; the DC pin includes an operating point control pin and an MPD current output pin; the operating point control pin is used to achieve stable control of the chip operating point through an external DC signal; the MPD current output pin is used to output the MPD current to an external detection unit.

[0016] Furthermore, the optical signal is input into the package shell through the input optical fiber and enters the waveguide input port of the electro-optic modulator chip through the dual-core FA coupling.

[0017] Furthermore, a mode field conversion structure is provided on the dual-core FA, and the mode field conversion structure converts the optical fiber 9 μm diameter mode spot into a d1 diameter mode spot.

[0018] Furthermore, an SSC mode field converter structure is provided on the electro-optic modulator chip, and the SSC mode field converter structure converts the d2 diameter mode spot of the waveguide structure of the electro-optic modulator chip into a d1 diameter mode spot.

[0019] Furthermore, the input optical fiber and the output optical fiber are both provided with metal parts, and an optical fiber sealing joint is installed on the packaging shell; the input optical fiber and the output optical fiber are welded and sealed with the optical fiber sealing joint; a tail tube is provided on the packaging shell; the optical fiber sealing joint and the tail tube are welded and sealed.

[0020] Furthermore, a transfer substrate a and a transfer substrate b are provided in the packaging shell; one end of the terminal matching film substrate is connected to one end of the transfer substrate a, the other end of the transfer substrate a is connected to one end of the transfer substrate b, and the other end of the transfer substrate b is connected to the operating point control pin and the MPD current output pin.

[0021] Compared with the prior art, the advantages of the present invention are:

[0022] (1) The present invention adopts an innovative waveguide structure and coupling method. The thin-film lithium niobate electro-optical modulator chip adopts a unique U-shaped waveguide design, and the waveguide input port and output port are located on the same side of the chip. By aligning the two ports simultaneously through a dual-core FA optical fiber for coupling operations, the space required for coupling is greatly reduced compared to traditional structures, and the convenience of coupling is improved. Traditional structures often require complex optical path layouts to achieve input and output coupling of optical signals, occupying a large space and making coupling adjustment difficult. The design of the present invention makes the coupling process more convenient and efficient, reduces the design and manufacturing complexity caused by spatial layout limitations, and is also conducive to improving the integration of the overall device, providing key support for miniaturization.

[0023] (2) The present invention achieves efficient mode spot conversion and low-loss coupling. By carefully designing a mode field conversion structure on a dual-core FA optical fiber, the larger optical fiber 9um diameter mode spot can be accurately converted into a d1 diameter mode spot, effectively reducing the mode spot size. At the same time, an SSC mode spot converter structure is equipped on the thin-film lithium niobate electro-optical modulator chip waveguide, which can enlarge the original d2 diameter mode spot of the chip waveguide to a d1 diameter mode spot. This two-way mode spot size adjustment allows the optical fiber mode spot size and the waveguide mode spot size to match each other, thereby achieving efficient and low-loss optical coupling. In fields such as optical communications, low-loss coupling has a vital impact on signal transmission quality and system performance. This feature of the present invention can significantly improve signal transmission efficiency, reduce signal attenuation, and reduce energy waste caused by coupling loss. It has obvious advantages over traditional modulators that are difficult to achieve precise mode spot matching.

[0024] (3) The RF feed port, optical input / output port, and DC pin of the present invention adopt a specific layout, that is, the RF feed port is located on the side of the device opposite to the optical input / output port and DC pin. This layout design fully considers the use needs and system integration requirements of the user terminal, and facilitates dense array arrangement in the user terminal. The port layout of the present invention effectively solves this problem, allowing multiple modulators to be arranged in an orderly manner within a limited space, reducing the space occupied by the overall system, improving the small integration level of the user terminal system, reducing the system construction cost, and improving the reliability and stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of the ultra-small, high-bandwidth, single-ended fiber-outlet thin-film lithium niobate electro-optic modulator of the present invention.

[0026] in:

[0027] 1. SSMP RF component, 2. High-frequency transition film substrate, 3. Electro-optical modulator chip, 4. Dual-core FA, 5. Terminal matching film substrate, 6. Transfer substrate a, 7. Transfer substrate b, 8. Input optical fiber, 9. Output optical fiber, 10. Working point control pin, 11. MPD current output pin, 12. Package shell, 13. Optical fiber sealing joint. DETAILED DESCRIPTION

[0028] The present invention will be further described below with reference to the accompanying drawings:

[0029] In order to solve the problems of high half-wave voltage, low bandwidth and large size of traditional bulk lithium niobate electro-optical modulator, the present invention proposes a single-ended thin-film lithium niobate electro-optical modulator with ultra-small size and high bandwidth.

[0030] like Figure 1 As shown, the ultra-small size and high bandwidth single-ended fiber-outlet thin film lithium niobate electro-optical modulator includes: an SSMP RF component 1, a high-frequency transition thin film substrate 2, an electro-optical modulator chip 3, a dual-core FA 4, a terminal matching thin film substrate 5, an input optical fiber 8, an output optical fiber 9 and a packaging shell 12.

[0031] The present invention is used to achieve impedance matching at the RF input end by designing an impedance high-frequency transition thin film substrate 2 and a packaging shell 12 structure. The terminal matching thin film substrate 5 is designed to achieve impedance matching at the RF output end. The use of dual-core FA optical fiber can achieve simultaneous alignment and coupling of the waveguide input port and the output port, which can reduce the space required for coupling and improve the convenience of coupling. The single-ended fiber-outlet thin film lithium niobate electro-optical modulator described in the present invention has an overall size of 26mm×8.4mm×7mm, a compact structure, and a small size. This design is to build a complete electro-optical modulator system, in which various components work together to achieve modulation and transmission of optical signals, and solve the problems of traditional bulk lithium niobate electro-optical modulators. Compared with traditional bulk lithium niobate electro-optical modulators, the present invention has been optimized from the overall architecture, and has been improved in the direction of miniaturization and high bandwidth to meet the needs of modern communications and other fields for miniaturization and high performance of devices.

[0032] Preferably, according to the present invention, the SSMP radio frequency component 1 is mounted on the packaging shell 12 for feeding radio frequency signals.

[0033] During electro-optical modulation, an external RF signal must be input into the electro-optical modulator chip to modulate the optical signal. The specific mounting location facilitates RF signal introduction and overall system integration. The standardized interface of the SSMP RF component facilitates connection to external RF sources, improving system compatibility and scalability.

[0034] According to a preferred embodiment of the present invention, the high-frequency transition film substrate 2 is disposed between the SSMP RF component 1 and the waveguide folded thin-film lithium niobate electro-optical modulator chip 3 to achieve impedance matching. The SSMP RF component 1 achieves impedance matching with the waveguide folded thin-film lithium niobate electro-optical modulator chip 3 via the high-frequency transition film substrate 2 to reduce RF signal reflections.

[0035] During RF signal transmission, impedance mismatches between different components can cause RF signal reflections, impacting modulation and signal quality. The high-frequency transition film substrate 2, through its specialized materials and structural design, adjusts the impedance along the signal transmission path, enabling efficient transmission of RF signals from the SSMP RF components to the electro-optical modulator chip.

[0036] The present invention is designed for impedance matching between the SSMP radio frequency component and the thin-film lithium niobate electro-optical modulator chip. By adopting a high-frequency transition thin film substrate 2, the radio frequency signal transmission link is optimized. Compared with traditional designs that may ignore or improperly handle impedance matching problems, the present invention reduces radio frequency signal reflections, improves signal transmission efficiency and modulator bandwidth performance.

[0037] Preferably, according to the present invention, the electro-optic modulator chip 3 is a waveguide folded thin film lithium niobate electro-optic modulator chip having a waveguide structure, an MPD electrode and a thermal modulation electrode for modulating optical signals.

[0038] The folded waveguide structure is an innovation compared to traditional straight waveguides. The electro-optic modulator chip integrates MPD electrodes and thermally tuned electrodes, enabling the chip to self-monitor and adjust its operating point, enhancing its functionality and adaptability. The electro-optic modulator operates by applying an external RF signal to change the refractive index of the lithium niobate waveguide, thereby modulating the optical signal. The electro-optic modulator chip 3 utilizes a folded waveguide structure to position the optical input and output waveguides on the same side of the chip, thereby locating the input and output optical fibers on the same side of the housing. Considering the potential bandwidth loss associated with chip waveguides, the present invention achieves high bandwidth through the following approaches: First, the electro-optic modulator chip itself has high bandwidth. Second, a high-frequency transition thin-film substrate is designed to achieve impedance matching between the SSMP RF component and the electro-optic modulator chip, minimizing signal reflections and increasing bandwidth. Third, a terminal matching thin-film substrate 5 achieves impedance matching at the terminals of the electro-optic modulator chip, further increasing bandwidth. The MPD electrodes monitor optical signal-related parameters, while the thermally tuned electrodes adjust the chip's operating point via an external DC signal to adapt to varying operating environments.

[0039] Preferably, the present invention utilizes a dual-fiber FA (i.e., dual-core FA 4) to implement an optical coupling design. Dual-core FA 4 is used to couple the optical signal from input fiber 8 into the waveguide structure of electro-optic modulator chip 3 and, at the output end, couple the optical signal from the waveguide structure of electro-optic modulator chip 3 back to output fiber 9.

[0040] Specifically, the dual-core structure can simultaneously process input and output optical signals, and through a specific optical design, achieves efficient coupling with the waveguide ports. Compared to the traditional single-core optical fiber method that processes input and output separately, the present invention uses a dual-core fiber optic (FA) to achieve simultaneous alignment and coupling of the waveguide input and output ports, significantly reducing the space required for coupling and improving coupling efficiency and convenience. This reduction in space allows for a further reduction in the overall modulator size, while the increased coupling efficiency reduces optical signal loss during the coupling process, thereby improving the overall system's optical transmission performance and energy efficiency.

[0041] According to a preferred embodiment of the present invention, the terminal matching film substrate 5 has three functions: first, it is used to achieve terminal impedance matching of the output electrode of the electro-optic modulator chip 3, ensuring stable transmission of the RF signal at the output end; second, it is connected to the thermal adjustment electrode of the electro-optic modulator chip 3 to control the operating point of the electro-optic modulator chip 3 by applying an external DC signal, ensuring the chip is in a suitable operating state; and third, it is connected to the MPD electrode of the electro-optic modulator chip 3 to extract the MPD current and connect it to an external detection unit for real-time monitoring of the chip's operating state. The terminal matching film substrate 5 includes a main substrate, a microstrip line structure provided on the main substrate for impedance matching with the electro-optic modulator chip, a microstrip line provided on the main substrate for connecting the thermal adjustment electrode to the operating point control pin, and a microstrip line provided on the main substrate for connecting the MPD electrode to the MPD current output pin. The main substrate material is aluminum nitride (ALN). Thin film substrates made of ALN can achieve higher frequency RF signal transmission. The microstrip line structure used for impedance matching is designed through radio frequency simulation to achieve good impedance matching with the electro-optic modulator chip.

[0042] Through the above design, the terminal matching film substrate 5 of the present invention integrates multiple functions into one, simplifying the system structure. Compared to implementing these functions separately with multiple components, this terminal matching film substrate 5 reduces the complexity of inter-component connections and signal transmission loss. Furthermore, by reducing the number of connection points and components, multifunctional integration improves system reliability, reduces the risk of system failure due to connection faults or component compatibility issues, and also facilitates system debugging and maintenance.

[0043] Preferably, according to the present invention, the electro-optic modulator chip 3 adopts a waveguide folded thin film lithium niobate electro-optic modulator chip, and the waveguide on the electro-optic modulator chip 3 is a U-shaped waveguide; the U-shaped waveguide has a U-shaped structure, and its waveguide input port and waveguide output port are located on the same side of the electro-optic modulator chip 3, and a radio frequency feed port is provided on the other side of the electro-optic modulator chip 3; the radio frequency feed port is used to feed an external radio frequency signal into the chip for electro-optical modulation.

[0044] This invention overcomes the limitations of traditional electro-optical modulators in high-speed modulation, compact size, and power consumption through a folded waveguide design, high-performance lithium niobate materials, optimized electrode design, and integrated design. The present invention places the waveguide input and output ports on the same side primarily to facilitate coupling with external optical fibers. When using a dual-core fiber array (FA) to achieve input and output coupling of optical signals, the two optical fiber cores of the dual-core FA can be simultaneously aligned with the waveguide input and output ports located on the same side. This layout greatly simplifies the alignment process between the optical fiber and the chip waveguide. Precise alignment between the optical fiber and waveguide is crucial for achieving efficient and low-loss coupling during optical coupling. The same-side port design enables high-precision alignment with a relatively simple mechanical structure and operation, reducing coupling losses caused by alignment errors.

[0045] The present invention sets the RF feed port on the other side opposite to the optical signal input and output port. The RF feed port and the optical input and output port are designed on both sides of the tube shell, which facilitates the array arrangement of electro-optical modulators at the user end and allows the installation of more electro-optical modulators within a limited space. The RF feed port and the optical input and output port are designed on opposite sides of the tube shell. This structural form can realize the array arrangement of electro-optical modulators at the user end, greatly saving the installation space at the user end and facilitating the miniaturization and integration of the user system.

[0046] According to a preferred embodiment of the present invention, since there is a certain distance and height difference between the waveguide folded thin-film lithium niobate electro-optical modulator chip 3 and the operating point control pin 10 and the MPD current output pin 11, direct gold wire bonding is not possible. Therefore, a transition connection is made via a transfer substrate a 6 and a transfer substrate b 7. One end of the terminal matching thin-film substrate is connected to one end of the transfer substrate a 6, and the other end of the transfer substrate a 6 is connected to one end of the transfer substrate b 7. The other end of the transfer substrate b 7 is connected to the operating point control pin 10 and the MPD current output pin 11.

[0047] The adapter substrate solution designed in this invention addresses the connection difficulties caused by structural differences between chips and pins, ensuring effective signal transmission and demonstrating ingenious structural adaptability. Through its appropriate shape, size, and material design, the adapter substrate bridges the gap between chip and pins, achieving a stable electrical connection.

[0048] Preferably, according to the present invention, the package shell 12 is provided with four DC pins on the same side of the optical input and output ports, two of which are operating point control pins, which realize stable control of the chip operating point through external DC signals; and the other two pins are MPD current output pins, which are used to output the MPD current to an external detection unit.

[0049] Because the chip electrodes are relatively far from the DC pins and there is a height difference, a stepped structure is designed within the package housing 12, and electrical connections are achieved via two transfer film substrates (i.e., transfer substrate a 6 and transfer substrate b 7). This pin layout facilitates connection to external circuits, and the stepped structure within the package housing and the electrical connections via two transfer film substrates (transfer substrate a and transfer substrate b) accommodate the unique positional relationship between the chip and the pins. The rational pin layout and internal transfer structure design optimize the DC signal transmission path and the chip's external connection, improving system operability and signal transmission stability. This allows for more precise chip operating point adjustment and MPD current monitoring, reduces errors caused by unstable signal transmission paths, and enhances the control and monitoring accuracy of the entire system.

[0050] According to a preferred embodiment of the present invention, the dual-core FA 4 is equipped with a mode field conversion structure that converts the optical fiber's 9µm diameter mode spot into a d1 diameter mode spot. The electro-optic modulator chip 3 is equipped with an SSC mode field converter structure that converts the d2 diameter mode spot of the electro-optic modulator chip's waveguide structure into a d1 diameter mode spot. After both the optical fiber's 9µm diameter mode spot and the chip's waveguide's d2 diameter mode spot are converted to a d1 diameter mode spot, low-loss optical coupling can be achieved.

[0051] By designing specific refractive index profiles or waveguide shapes, the distribution and propagation characteristics of the optical field can be altered, enabling conversion of the mode spot size to achieve low-loss coupling between the optical fiber and the waveguide. Compared to traditional approaches that consider coupling only in a single direction, the bidirectional mode field conversion design employed in this invention matches the mode spot size from both the optical fiber and the waveguide, significantly improving coupling efficiency and reducing coupling losses. This precise mode field conversion maintains excellent coupling performance under varying operating conditions and optical signal characteristics, improving the system's adaptability and compatibility with optical signals and mitigating coupling performance degradation caused by variations in optical signal characteristics.

[0052] The working principle of the single-ended thin-film lithium niobate electro-optical modulator described in the present invention is:

[0053] The optical signal is input through the input optical fiber 8 and coupled into the waveguide input port through the dual-core FA 4. The optical signal is coupled into the electro-optic modulator chip 3, and after being transmitted through the U-shaped waveguide in the electro-optic modulator chip 3, it is coupled into the output optical fiber 9 through the waveguide output port. Under the action of the radio frequency signal fed into the electro-optic modulator chip 3 by the SSMP radio frequency component 1, the optical signal transmitted in the waveguide of the electro-optic modulator chip 3 is modulated. Part of the length of the input optical fiber 8 and the output optical fiber 9 is metallized and welded and sealed with the optical fiber sealing joint 13. The optical fiber sealing joint 13 is welded and sealed with the tail tube of the packaging shell 12 to achieve optical fiber airtight packaging, ensuring the long-term working stability and reliability of the device. The present invention can achieve optical coupling in a smaller space, and at the same time solves the connection problem caused by the height difference and long distance between the electro-optic modulator chip and the DC pin.

[0054] In summary, the present invention organically integrates various components into a complete workflow. By optimizing the collaborative operation of these components, it achieves efficient electro-optical modulation and stable signal transmission, while also focusing on the long-term stability of the device, thereby achieving system-level innovation based on the principles of traditional electro-optical modulation. The collaborative optimization of the various components in the electro-optical modulator described in the present invention can minimize the performance degradation of the entire modulator during long-term operation, achieving reliability far exceeding expectations, reducing maintenance and replacement costs due to device aging or environmental factors, and improving the cost-effectiveness of the system over its entire life cycle.

[0055] The above-described embodiments are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. An ultra-small, high-bandwidth, single-ended, thin-film lithium niobate electro-optic modulator, characterized in that: The electro-optic modulator comprises: an SSMP radio frequency component (1), a high-frequency transition film substrate (2), an electro-optic modulator chip (3), a dual-core FA (4), a terminal matching film substrate (5), an input optical fiber (8), an output optical fiber (9) and a packaging shell (12); The SSMP radio frequency component (1) is mounted on the packaging shell (12) and is used for feeding in radio frequency signals; The high-frequency transition thin film substrate (2) is arranged between the SSMP radio frequency component (1) and the electro-optic modulator chip (3) to achieve impedance matching; The electro-optic modulator chip (3) adopts a waveguide folded thin film lithium niobate electro-optic modulator chip, which is used to modulate the optical signal and includes a radio frequency electrode, a waveguide structure, an MPD electrode and a thermal modulation electrode; The dual-core FA (4) is used to couple the optical signal of the input optical fiber (8) to the waveguide structure of the electro-optical modulator chip (3), and to couple the optical signal from the waveguide structure of the electro-optical modulator chip (3) back to the output optical fiber (9) at the output end; The terminal matching thin film substrate (5) is used to achieve terminal impedance matching of the output terminal electrode of the electro-optic modulator chip (3), and is connected to the thermal adjustment electrode of the electro-optic modulator chip (3), realizes the working point control of the electro-optic modulator chip (3) by loading an external DC signal, and is also connected to the MPD electrode of the electro-optic modulator chip (3) to lead out the MPD current; The electro-optic modulator chip (3) adopts a waveguide folded thin film lithium niobate electro-optic modulator chip, and the waveguide structure on the electro-optic modulator chip (3) is a U-shaped waveguide; the waveguide input port and the waveguide output port of the U-shaped waveguide are located on the same side of the electro-optic modulator chip (3), and a radio frequency feed port is provided on the other side of the electro-optic modulator chip (3); the radio frequency feed port is used to feed an external radio frequency signal into the electro-optic modulator chip (3) for electro-optical modulation.

2. The ultra-small, high-bandwidth, single-ended thin-film lithium niobate electro-optic modulator according to claim 1, characterized in that: The packaging shell (12) is provided with a DC pin on the same side as the optical input and output ports; The DC pins include an operating point control pin (10) and an MPD current output pin (11); The operating point control pin (10) is used to achieve stable control of the chip operating point through an external DC signal; The MPD current output pin (11) is used to output the MPD current to an external detection unit.

3. The ultra-small, high-bandwidth, single-ended thin-film lithium niobate electro-optic modulator according to claim 1, characterized in that: The optical signal is input into the package housing (12) through the input optical fiber (8) and coupled into the waveguide input port of the electro-optic modulator chip (3) through the dual-core FA (4).

4. The ultra-small, high-bandwidth, single-ended thin-film lithium niobate electro-optic modulator according to claim 1, characterized in that: The dual-core FA (4) is provided with a mode field conversion structure, and the mode field conversion structure converts the optical fiber 9 μm diameter mode spot into a d1 diameter mode spot.

5. The ultra-small, high-bandwidth, single-ended thin-film lithium niobate electro-optic modulator according to claim 1, characterized in that: An SSC mode field converter structure is provided on the electro-optic modulator chip (3), and the SSC mode field converter structure converts a d2 diameter mode spot of the waveguide structure of the electro-optic modulator chip (3) into a d1 diameter mode spot.

6. The ultra-small, high-bandwidth, single-ended thin-film lithium niobate electro-optic modulator according to claim 1, characterized in that: The input optical fiber (8) and the output optical fiber (9) are both provided with metal parts, and an optical fiber sealing joint (13) is installed on the packaging shell (12); the input optical fiber (8) and the output optical fiber (9) are welded and sealed with the optical fiber sealing joint (13); a tail tube is provided on the packaging shell (12); the optical fiber sealing joint (13) and the tail tube are welded and sealed.

7. The ultra-small, high-bandwidth, single-ended thin-film lithium niobate electro-optic modulator according to claim 2, characterized in that: A transfer substrate a (6) and a transfer substrate b (7) are provided in the packaging shell (12); One end of the terminal matching film substrate (5) is connected to one end of the transfer substrate a (6), the other end of the transfer substrate a (6) is connected to one end of the transfer substrate b (7), and the other end of the transfer substrate b (7) is connected to an operating point control pin (10) and an MPD current output pin (11).

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