Microminiature high-bandwidth single-end fiber-outgoing film lithium niobate electro-optical modulator

Abstract

The invention relates to a subminiature high-bandwidth single-ended fiber-outgoing film lithium niobate electro-optical modulator, which comprises an SSMP radio frequency assembly, a high-frequency transition film substrate, an electro-optical modulator chip, a dual-core FA, a terminal matching film substrate, an input optical fiber, an output optical fiber and a packaging shell. According to the thin-film lithium niobate electrooptical modulator chip, the waveguide is of a U-shaped structure, the waveguide input port and the waveguide output port are located on the same side of the chip, the dual-core FA is adopted to align the waveguide input port and the waveguide output port for coupling, the space needed by coupling is reduced, and the coupling convenience is improved; a mode field conversion structure is designed on the double-core FA, and the size of an optical fiber spot size is reduced; an SSC spot size converter structure is designed on a chip waveguide, the size of a waveguide spot size is amplified, the size of an optical fiber spot size and the size of a waveguide spot size are converted into the same size, and efficient and low-loss coupling is achieved. The radio frequency feed-in port, the optical input and output port and the direct current pin are located on the opposite side of the device, so that the user terminal array type dense arrangement is facilitated, and the small-sized integration of the system is realized.

Description

Technical Field

[0001] The 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 with traditional electrical transmission technology, microwave photonic transmission links have obvious advantages such as high bandwidth, low loss, light weight and strong anti-electromagnetic interference ability, and are widely used in the communication field. As the core key optoelectronic device in microwave photonic transmission links, electro-optical modulators play the role of converting electrical signals into optical signals.

[0003] At present, traditional bulk lithium niobate electro-optic modulators are mostly used in microwave photon transmission links to achieve the above functions. However, due to the limitations of bulk lithium niobate material properties and chip design, traditional bulk lithium niobate electro-optic modulators have disadvantages such as high half-wave voltage, low bandwidth, large size, and heavy weight, which restricts further application development.

[0004] Thin-film lithium niobate electro-optic modulator chips can be developed based on the emerging lithium niobate thin film materials 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-outlet thin-film lithium niobate electro-optic modulator in order to solve the drawbacks 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-optic modulator comprises: an SSMP radio frequency component, a high-frequency transition film substrate, an electro-optic modulator chip, a dual-core FA, a terminal matching 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 in 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-optic modulator chip, and couple the optical signal from the waveguide structure of the electro-optic modulator chip back to the output optical fiber at the output end.

[0013] The terminal matching film substrate is used to achieve terminal impedance matching of the output terminal electrode of the electro-optic modulator chip, and is connected to the thermal adjustment electrode of the electro-optic modulator chip to achieve working point control of the electro-optic modulator chip by loading an external DC signal, and is also connected to the MPD electrode of the electro-optic modulator chip to lead 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 of 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 housing 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 9 um diameter mode spot of the optical fiber 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 a 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 arranged 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 a, and the other end of the transfer substrate a 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-optic 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 with the dual-core FA optical fiber for coupling operations at the same time, compared with the traditional structure, the space volume required for coupling is greatly reduced, and the convenience of coupling is improved. Traditional structures often require complex optical path layouts to achieve input and output coupling of optical signals, which occupies a large space and is difficult to adjust the coupling. 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 realizes efficient mode spot conversion and low-loss coupling. By carefully designing the mode field conversion structure on the 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, the SSC mode spot converter structure is equipped on the thin-film lithium niobate electro-optic 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 realizing efficient and low-loss optical coupling. In the fields of 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 in 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 requirements and system integration requirements of the user terminal, and is convenient for 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 in a limited space, reducing the space occupation of 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-optic 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 in conjunction with 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-optic modulator, the present invention proposes a single-ended thin-film lithium niobate electro-optic modulator with ultra-small size and high bandwidth.

[0030] like Figure 1 As shown, the single-ended fiber-outlet thin-film lithium niobate electro-optic modulator with ultra-small dimensions and high bandwidth includes: an SSMP RF component 1, a high-frequency transition thin-film substrate 2, an electro-optic modulator chip 3, a dual-core FA4, 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 film substrate 2 and a packaging shell 12 structure. The terminal matching film substrate 5 is designed to achieve impedance matching at the RF output end. The dual-core FA optical fiber is used to 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 is optimized from the overall architecture, and 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] In the electro-optical modulation process, an external RF signal needs to be input into the electro-optical modulator chip to achieve modulation of the optical signal. The specific installation position design facilitates the introduction of RF signals and the integration of the overall system. The standardized interface form of SSMP RF components is used to facilitate connection with external RF sources, improving the compatibility and scalability of the system.

[0034] Preferably, according to 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-optic modulator chip 3 to achieve impedance matching. The SSMP RF component 1 achieves impedance matching with the waveguide folded thin-film lithium niobate electro-optic modulator chip 3 through the high-frequency transition film substrate 2 to reduce RF signal reflection.

[0035] During the transmission of RF signals, if the impedances of different components do not match, it will cause RF signal reflection, affecting the modulation effect and signal quality. The high-frequency transition film substrate 2 adjusts the impedance on the signal transmission path through specific material and structural design, so that the RF signal can be efficiently transmitted from the SSMP RF component to the electro-optic modulator chip.

[0036] The present invention is designed for impedance matching between SSMP radio frequency components and thin-film lithium niobate electro-optic modulator chips. 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 radio frequency signal reflection is reduced, and the signal transmission efficiency and the bandwidth performance of the modulator are improved.

[0037] Preferably, according to the present invention, the electro-optic modulator chip 3 adopts 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 waveguide folding structure is an innovation relative to the traditional straight waveguide. The electro-optic modulator chip integrates MPD electrodes and thermal adjustment electrodes, so that the chip has the ability of self-monitoring and working point adjustment, and enhances the functionality and adaptability of the chip. The principle of the electro-optic modulator is to change the refractive index of the lithium niobate waveguide by applying an external radio frequency signal, thereby realizing the function of optical signal modulation. The electro-optic modulator chip 3 adopts a waveguide folding structure in order to make the optical input waveguide and the optical output waveguide located on the same side of the chip, so as to realize that the input optical fiber and the output optical fiber are located on the same side of the tube shell. Considering that the chip waveguide may lose bandwidth, the present invention adopts the following methods to achieve high bandwidth: first, the electro-optic modulator chip itself has a high bandwidth; second, by designing a high-frequency transition film substrate, the impedance matching between the SSMP radio frequency component and the electro-optic modulator chip is realized, the signal reflection is reduced, and the bandwidth is increased; third, the terminal matching film substrate 5 can realize the terminal impedance matching of the electro-optic modulator chip and increase the bandwidth. The MPD electrode is used to monitor the parameters related to the optical signal, and the thermal adjustment electrode can adjust the chip working point through an external DC signal to adapt to different working environment requirements.

[0039] Preferably, the present invention uses a dual optical fiber FA (i.e., dual core FA4) to implement an optical coupling design. The dual core FA4 is used to couple the optical signal of the input optical fiber 8 to the waveguide structure of the electro-optic modulator chip 3, and couple the optical signal from the waveguide structure of the electro-optic modulator chip 3 back to the output optical fiber 9 at the output end.

[0040] Specifically, the dual-core structure can process input and output optical signals at the same time, and achieve efficient coupling with the waveguide port through a specific optical design. Compared with the traditional single-core optical fiber that processes input and output separately, the present invention uses a dual-core FA to achieve simultaneous alignment and coupling of the waveguide input port and output port, greatly reducing the space required for coupling and improving coupling efficiency and convenience. The reduction in space allows the volume of the entire modulator to be further reduced, while the improvement in coupling efficiency reduces the loss of optical signals during the coupling process, thereby improving the optical transmission performance and energy utilization of the entire system.

[0041] According to the 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 terminal electrode of the electro-optic modulator chip 3 to ensure stable transmission of the RF signal at the output terminal; second, it is connected to the thermal adjustment electrode of the electro-optic modulator chip 3 to achieve working point control of the electro-optic modulator chip 3 by loading an external DC signal to ensure that the chip is in a suitable working state; third, it is connected to the MPD electrode of the electro-optic modulator chip 3 to connect the MPD current to an external detection unit so as to monitor the working state of the chip in real time. The terminal matching film substrate 5 includes a main substrate, a microstrip line structure for impedance matching with the electro-optic modulator chip arranged on the main substrate, a microstrip line for connecting the thermal adjustment electrode with the working point control pin arranged on the main substrate, and a microstrip line for connecting the MPD electrode with the MPD current output pin arranged on the main substrate. The material of the substrate body is ALN, and the film substrate prepared by ALN can achieve higher frequency RF signal transmission. The microstrip line structure used for impedance matching is designed by radio frequency simulation, and can achieve good impedance matching with the electro-optic modulator chip.

[0042] Through the above design, the terminal matching film substrate 5 in the present invention integrates multiple functions into one, simplifies the system structure, and reduces the connection complexity and signal transmission loss between components compared to setting up multiple components to realize these functions. In addition, because the number of connection points and components is reduced, multi-functional integration improves the reliability of the system, reduces the risk of system failure caused by connection failure or compatibility problems between components, and also facilitates the debugging and maintenance of the system.

[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 RF feed port is provided on the other side of the electro-optic modulator chip 3; the RF feed port is used to feed an external RF signal into the chip for electro-optical modulation.

[0044] The present invention solves the limitations of traditional electro-optic modulators in terms of high-speed modulation, compact size, power consumption, etc. through waveguide folding design, high-performance lithium niobate material, optimized electrode design and integrated design. The present invention sets the waveguide input port and output port on the same side mainly to facilitate coupling connection with external optical fibers. When a dual-core FA (fiber array) is used to realize the 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 port and output port located on the same side. This layout greatly simplifies the alignment process of the optical fiber and the chip waveguide. In the optical coupling process, precise alignment between the optical fiber and the waveguide is the key to achieving efficient and low-loss coupling, and the same-side port design enables the dual-core FA to achieve high-precision alignment with a relatively simple mechanical structure and operation method, 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 is convenient for realizing the array arrangement of electro-optical modulators at the user end, and more electro-optical modulators can be installed in a limited space. The RF feed port and the optical input and output port are designed on the opposite side 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 the preferred embodiment of the present invention, since there is a certain distance and height difference between the waveguide folded thin film lithium niobate electro-optic modulator chip 3 and the working point control pin 10 and the MPD current output pin 11, it is impossible to directly connect them by gold wire bonding, so transition connection is made through the transfer substrate a 6 and the transfer substrate b 7. One end of the terminal matching thin film substrate 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 a 7, and the other end of the transfer substrate a 7 is connected to the working point control pin 10 and the MPD current output pin 11.

[0047] In view of the difficulty of connecting the chip and the pin, the transfer substrate solution designed by the present invention solves the connection difficulties caused by structural differences and ensures the effective transmission of signals. It is an ingenious structural adaptability design. The transfer substrate makes up for the connection differences between the chip and the pin through the appropriate shape, size and material design to achieve a stable electrical connection.

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

[0049] Since the chip electrode is far away from the DC pin and there is a height difference, a step structure is designed inside the package shell 12 and electrical connection is achieved through two transfer film substrates (i.e., transfer substrate a 6 and transfer substrate b 7). This pin layout is convenient for connection with the external circuit, and a step structure is designed inside the package shell and electrical connection is achieved through two transfer film substrates (transfer substrate a and transfer substrate b) to adapt to the special positional relationship between the chip and the pin. Reasonable pin layout and internal transfer structure design optimize the transmission path of the DC signal and the connection method between the chip and the outside, improve the operability of the system and the stability of signal transmission, make the chip operating point adjustment and MPD current monitoring more accurate, reduce the error caused by the instability of the signal transmission path, and improve the control accuracy and monitoring accuracy of the entire system.

[0050] Preferably, according to the present invention, the dual-core FA 4 is provided with a mode field conversion structure, and the mode field conversion structure converts the optical fiber 9um diameter mode spot into a d1 diameter mode spot. The electro-optic modulator chip 3 is provided with an SSC mode field converter structure, 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. After the optical fiber 9um diameter mode spot and the chip waveguide d2 diameter mode spot are both converted into a d1 diameter mode spot, optical coupling with lower loss can be achieved.

[0051] By designing a specific refractive index distribution or waveguide shape, etc., the distribution and propagation characteristics of the light field can be changed, and the mode spot size can be converted to achieve low-loss coupling between the optical fiber and the waveguide. Compared with the traditional method of considering coupling only from a single direction, the bidirectional mode field conversion design adopted by the present invention matches the mode spot size from both the optical fiber and the waveguide, greatly improving the coupling efficiency and reducing the coupling loss. This precise mode field conversion can maintain a good coupling effect under different working conditions and optical signal characteristics, improve the system's adaptability and compatibility to optical signals, and reduce the problem of coupling performance degradation caused by changes in optical signal characteristics.

[0052] The working principle of the single-ended thin-film lithium niobate electro-optic 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, welded and sealed with the optical fiber sealing node 13, and the optical fiber sealing node 13 is welded and sealed with the tail tube of the packaging shell 12 to achieve airtight packaging of the optical fiber, thereby ensuring the long-term working stability and reliability of the device. The present invention can realize optical coupling in a smaller space, and at the same time solves the connection problem caused by the long distance between the electro-optic modulator chip and the DC pin due to the height difference.

[0054] In summary, the present invention organically combines various components in a complete workflow, realizes efficient electro-optical modulation and stable signal transmission by optimizing the collaborative work of various components, and pays attention to the long-term stability of the device, thereby realizing system-level innovation based on the traditional electro-optical modulation principle. The collaborative optimization of various components in the electro-optical modulator described in the present invention may make the performance of the entire modulator decrease less during long-term operation, and the reliability is far beyond expectations, reducing the maintenance and replacement costs caused by device aging or environmental factors, and improving the cost performance 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 design 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 all 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 optical signals and comprises 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) into the waveguide structure of the electro-optic modulator chip (3), and to couple the optical signal from the waveguide structure of the electro-optic 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.

2. The ultra-small high-bandwidth single-ended thin-film lithium niobate electro-optic modulator according to claim 1 is characterized in that: 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-optic modulation.

3. The ultra-small high-bandwidth single-ended thin-film lithium niobate electro-optic modulator according to claim 1 is 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.

4. The ultra-small high-bandwidth single-ended thin-film lithium niobate electro-optic modulator according to claim 1 is characterized in that: The optical signal is input into the packaging 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).

5. The ultra-small high-bandwidth single-ended thin-film lithium niobate electro-optic modulator according to claim 1 is characterized in that: The dual-core FA (4) is provided with a mode field conversion structure, which converts the optical fiber 9um diameter mode spot 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 is characterized in that: The electro-optic modulator chip (3) is provided with an SSC mode field converter structure, 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.

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

8. The ultra-small high-bandwidth single-ended thin-film lithium niobate electro-optic modulator according to claim 3 is characterized in that: A transfer substrate a (6) and a transfer substrate b (7) are arranged in the packaging shell (12); One end of the terminal matching film substrate (5) is connected to one end of the adapter substrate a (6), the other end of the adapter substrate a (6) is connected to one end of the adapter substrate a (7), and the other end of the adapter substrate a (7) is connected to an operating point control pin (10) and an MPD current output pin (11).

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