A high performance radio frequency modulated light emitting module

Abstract

The application relates to a high-performance radio frequency modulation light emitting module, which comprises a radio frequency light modulation part, a circuit module and a shell module; the radio frequency light modulation part comprises a laser coupling module, a modulator module, an optical fiber assembly and a radio frequency transmission module; the laser coupling module is used for outputting an optical signal and coupling the output optical signal into the modulator module; the modulator module is used for radio frequency modulation of the optical signal and coupling the modulated optical carrier radio frequency signal into the optical fiber assembly; the radio frequency transmission module is used for transmitting the radio frequency signal to the modulator module; the circuit module is used for realizing control, monitoring and power supply functions; and the shell module is used for separating the circuit module and the radio frequency light modulation part upwards and downwards and sealing and packaging the radio frequency light modulation part. The application constructs a radio frequency modulation light module with high reliability and high performance, and meets the requirements of wide long-distance radio frequency transmission. In addition, the structure meets the requirements of equipment miniaturization and high integration.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of radio frequency optical link, in particular to a high-performance radio frequency modulation optical transmitting module, mainly applied to the field of long-range radio frequency transmission such as optical carrier radio frequency, radio astronomy and radar system. BACKGROUND

[0002] Radio frequency link is an important part of many communication systems, and is widely used in aerospace, radar, remote sensing and telemetry fields. However, when facing long-distance transmission, the transmission loss of traditional cable and radio frequency waveguide transmission medium increases rapidly, and the reference Figure 1 , for example, the X-band loss of typical coaxial cable is higher than 1.8dB / m, which is difficult to realize long-distance radio frequency transmission.

[0003] Compared with the above, the transmission loss of typical single-mode communication optical fiber is less than 0.2dB / km, which is much smaller than that of traditional cable and is suitable for long-distance transmission. Therefore, modulating radio frequency signal to optical carrier to obtain the low-loss transmission capability of optical waveguide is an effective way for long-distance transmission of radio frequency signal, as Figure 2 .

[0004] On the other hand, radio frequency optical link often has the characteristics of complex application scene and harsh application environment, and the existing solutions shown in Figure 1 and Figure 2 cannot meet the increasing demand. The existing radio frequency link cannot guarantee high reliability and high performance, and the structure design is also quite complicated and redundant, not compact enough, which cannot meet the requirements of device miniaturization and high integration.

[0005] Therefore, how to overcome the defects or needs of the prior art and solve the above technical problems is a difficult problem to be solved in the technical field. SUMMARY

[0006] In view of the defects or improvement needs in the prior art: the existing radio frequency link cannot guarantee high reliability and high performance, and the structure design is also quite complicated and redundant, which cannot meet the requirements of device miniaturization and high integration, etc. The present application proposes a high-performance radio frequency modulation optical transmitting module to meet the application of long-distance transmission of radio frequency signal, especially for the application scene with high reliability and radio frequency performance requirements.

[0007] The embodiment of the present application adopts the following technical scheme:

[0008] The application provides a high-performance radio frequency modulation light emitting module, which comprises a radio frequency light modulation part, a circuit module and a shell module, the radio frequency light modulation part comprises a laser coupling module, a modulator module, a fiber assembly and a radio frequency transmission module, the laser coupling module is used for outputting a light signal and coupling the output light signal into the modulator module, the modulator module is used for radio frequency modulation of the light signal and coupling the modulated light carrier radio frequency signal into the fiber assembly, the radio frequency transmission module is used for transmitting a radio frequency signal to the modulator module, the circuit module is used for realizing control, monitoring and power supply functions, and the shell module is used for separating the circuit module and the radio frequency light modulation part upward and downward and sealing and packaging the radio frequency light modulation part.

[0009] Further, the laser coupling module comprises a laser, a collimating lens and a focusing lens, wherein the constant power laser output by the laser is coupled into the waveguide of the modulator module in sequence through the collimating lens and the focusing lens.

[0010] Further, the laser coupling module further comprises an isolator, which is arranged between the collimating lens and the focusing lens and is used for isolating the back-returning light.

[0011] Further, the modulator module comprises a modulator, a radio frequency base, a modulator radio frequency load, a direct current bias and a PD, wherein the waveguide of the modulator is used for receiving the light signal output by the laser coupling module and is used for aligning and coupling the modulated light carrier radio frequency signal from the output waveguide end into the fiber assembly, the modulator radio frequency load is used for consuming residual radio frequency signal energy, the direct current bias interface provides a certain direct current bias for the modulator, and the PD is used for monitoring the modulated light signal leaked from the side of the modulator, and the modulator, the modulator radio frequency load, the direct current bias and the PD are all installed on the radio frequency base.

[0012] Further, the fiber assembly comprises a fiber fixing block and a fiber, the fiber core of the fiber and the output waveguide end of the modulator are aligned to realize mode field matching, so as to couple the modulated light carrier radio frequency signal into the fiber, and the fiber and the modulator are fixed through the fiber fixing block.

[0013] Further, the fiber fixing block comprises a fiber V-shaped seat and a fiber cover, the fiber is clamped between the fiber V-shaped seat and the fiber cover, and the fiber and the fiber V-shaped seat and the fiber cover are bonded through glue filling.

[0014] Furthermore, the fiber optic V-shaped bracket and the fiber optic cap are made of glass and have a coefficient of thermal expansion that matches that of the fiber optic cable. The coating on the clamped portion of the fiber optic cable is removed, and the end faces of the fiber optic V-shaped bracket, the fiber optic cap, and the fiber optic cable are made flush through grinding. When coupling and fixing the fiber optic cable and the modulator, the fiber optic fixing block and the fiber optic cable are prefabricated into a single fiber optic assembly with flush end faces. Then, the fiber optic assembly is optically coupled to align the fiber core with the waveguide of the modulator. Finally, the end face of the fiber optic V-shaped bracket is bonded to the non-waveguide area on the side of the modulator to complete the coupling and fixing of the fiber optic cable and the modulator.

[0015] Furthermore, the radio frequency transmission module includes a radio frequency input head, a microwave matching network, a low-noise amplifier, and an equalizer. The radio frequency signal to be transmitted is input from the radio frequency input head and transmitted through the microwave matching network. The low-noise amplifier and the equalizer are disposed in the microwave matching network to amplify the power of the original radio frequency signal. The radio frequency input head, the microwave matching network, the low-noise amplifier, and the equalizer are connected by a gold strip.

[0016] Furthermore, the circuit module includes a circuit board and an electrical interface. The electrical interface is connected to the circuit board via one or more of the following: soldering, gold wire, and gold strip. The electrical interface provides external power to the internal components and provides internal operating status information to the external components.

[0017] Furthermore, the outer casing module includes a tube shell, an upper cover plate, and a lower cover plate. A middle spacer is provided in the middle of the tube shell. A highly airtight sealed space is formed between the upper cover plate and the middle spacer of the tube shell using resistance welding, allowing the radio frequency (RF) optical modulation section to be installed in this upper sealed space. The lower cover plate is fixed to the tube shell, and the circuit module is installed in the lower space formed by the middle spacer between the lower cover plate and the tube shell. An optical fiber tail tube is provided on one side of the tube shell for extending the optical fiber of the optical fiber assembly. An RF input tube is provided on the other side of the tube shell for installing the RF input head of the RF transmission module. The bottom of the tube shell is provided with mounting ears for connecting the module to the outside. The tube shell is provided with glass insulating pins, which include a conductive pin located in the center and a glass insulator welded to the middle part of the conductive pin. The length of the glass insulator is shorter than the length of the conductive pin. The glass insulating pin is sintered into the tube shell through the glass insulator. The two ends of the conductive pin are flat, with one end located in the sealed space in the upper part of the tube shell and the other end located in the lower part of the tube shell, so as to be bonded to the components to be connected by gold wire respectively.

[0018] Compared with existing technologies, the advantages of this invention are as follows: By employing a spatial light-based LD laser coupling scheme, a lithium niobate modulator-based RF external modulation scheme, an optical fiber-based output scheme, a hermetically sealed optical packaging scheme, and a high-performance RF connection scheme, a highly reliable and high-performance RF modulation optical module is constructed, meeting a wide range of long-distance RF transmission needs. Furthermore, its ingenious structural design results in a compact structure that saves space, meeting current requirements for device miniaturization and high integration. Attached Figure Description

[0019] 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.

[0020] Figure 1 A schematic diagram of conventional radio frequency cable transmission is provided for the background art of this invention;

[0021] Figure 2 A schematic diagram of an existing optical radio frequency transmission scheme provided as background for this invention;

[0022] Figure 3 An exploded view of a high-performance radio frequency modulation optical emission module provided in an embodiment of the present invention;

[0023] Figure 4 A schematic diagram illustrating the principle of a high-performance radio frequency modulation optical emission module provided in an embodiment of the present invention;

[0024] Figure 5 This is a schematic cross-sectional view of the optical fiber fixing part provided in an embodiment of the present invention;

[0025] Figure 6 This is a schematic diagram of the overall implementation of the radio frequency-optical path integration provided in an embodiment of the present invention;

[0026] Figure 7 This is a schematic diagram of the modulator module structure provided in an embodiment of the present invention;

[0027] Figure 8 This is a schematic diagram of the circuit module structure provided in an embodiment of the present invention;

[0028] Figure 9 This is a cross-sectional schematic diagram of the outer shell module provided in an embodiment of the present invention;

[0029] Figure 10 This is a schematic diagram of a housing module with the top cover removed, provided in an embodiment of the present invention.

[0030] Figure 11This is a schematic diagram of the glass-insulated PIN structure provided in an embodiment of the present invention;

[0031] Figure 12 This is a schematic diagram of the microwave matching network arrangement provided in an embodiment of the present invention. Detailed Implementation

[0032] 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.

[0033] It should be noted that, in the embodiments of this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a method or apparatus that includes a list of elements includes not only the elements expressly described, but also other elements not expressly listed, or elements inherent to implementing the method or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of other related elements (e.g., steps in the method or units in the apparatus, such as portions of circuitry, processors, programs, or software, etc.) in the method or apparatus that includes that element.

[0034] 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, and the order of the steps can be changed as long as they are logical and do not conflict. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0035] It must first be stated that in the background technology Figure 1 This is a schematic diagram of traditional radio frequency cable transmission, intended to illustrate the shortcomings of the traditional method of transmitting radio frequency signals using cables, as stated in the first paragraph of the "Background Technology": "The X-band loss of coaxial cables is higher than 1.8dB / m, making it difficult to achieve long-distance radio frequency transmission." Figure 2 The diagram below illustrates an existing optical-to-RF transmission scheme. The "continuous laser source," "MZM modulator," and external "RF modulation signal" and "DC bias" signal sources are all discrete components, resulting in a cumbersome system and reduced reliability due to numerous interconnection nodes. This design addresses this issue by integrating components and optimizing the integration process to improve performance.

[0036] Example 1:

[0037] This invention aims to meet the needs of long-distance radio frequency (RF) signal transmission applications, especially for applications with high reliability and RF performance requirements, by designing a high-performance RF modulation optical transmission module. To achieve the above objective, this invention provides a high-performance RF modulation optical transmission module with the following features: a spatial light-based LD (Laser Diode) laser coupling scheme, an RF modulation scheme based on MZM (Mach-Zehnder Modulator) external modulation technology, an fiber-optic output scheme, a highly hermetically tight optical packaging scheme, and a high-performance RF link scheme.

[0038] The spatial light-based LD laser coupling scheme involves stably and efficiently coupling the light output from the LD into the lithium niobate modulator waveguide through a collimating lens and a focusing lens.

[0039] The MZM external modulation technique described above operates the laser in a constant state, modulating the radio frequency signal onto the optical signal using an MZM modulator. Compared to direct modulation, external modulation achieves a lower noise figure and a higher dynamic range, making it an ideal method for high-performance radio frequency modulation.

[0040] The fiber-optic-based output scheme couples the radio frequency modulated optical signal from the modulator output end into the optical fiber, enabling the modulated optical signal to be output stably and transmitted with low loss.

[0041] The high-airtightness optical packaging solution encapsulates the laser, lens, modulator, fiber coupling parts, etc., into the module shell in an airtight manner to isolate them from the external environment, thereby improving the reliability of the device.

[0042] The high-performance RF connection scheme refers to the RF connection method between the external RF signal to be transmitted and the lithium niobate modulator, which meets the requirements of low modulation distortion, wide bandwidth, and high gain.

[0043] Preferably, the LD laser source can be a high-power, low-RIN (Relative Intensity Noise) laser, which is beneficial for achieving higher gain and a larger link dynamic range. The LD includes, but is not limited to, FP (Fabry-Perot), VCSEL (Vertical Cavity Surface Emitting Laser), DFB (Distributed Feedback Laser), and other types.

[0044] Preferably, the collimating lens and the focusing lens can be aspherical lenses to reduce spherical aberration and phase difference, thereby achieving higher coupling efficiency.

[0045] Preferably, the lithium niobate modulator can have a large bandwidth, low phase noise and low half-wave voltage, which is beneficial to improving the link bandwidth and spurious-free dynamic range.

[0046] The above is the overall concept of the present invention. The present invention will be described in more detail below through specific structural components and embodiments.

[0047] like Figure 3 As shown, this embodiment of the invention provides a high-performance radio frequency modulation optical transmission module, including a radio frequency optical modulation section, a circuit module 5, and a housing module 6. The radio frequency optical modulation section includes a laser coupling module 1, a modulator module 2, an optical fiber assembly 3, and a radio frequency transmission module 4. The laser coupling module 1 is used to output an optical signal and couple the output optical signal to the modulator module 2. The modulator module 2 is used to perform radio frequency modulation on the optical signal and couple the modulated optical carrier radio frequency signal to the optical fiber assembly 3. The radio frequency transmission module 4 is used to transmit radio frequency signals to the modulator module 2. The circuit module 5 is used to realize control, monitoring, and power supply functions. The housing module 6 is used to separate the circuit module 5 and the radio frequency optical modulation section and to seal and encapsulate the radio frequency optical modulation section.

[0048] refer to Figure 4 In a preferred embodiment, the laser coupling module 1 includes a laser 101, a collimating lens 102, and a focusing lens 104. The constant-power laser output from the laser 101 is coupled to the waveguide of the modulator module 2 after passing through the collimating lens 102 and the focusing lens 104. Specifically, the laser coupling module 1 couples the constant-power laser output from the laser 101 (a semiconductor laser, i.e., the aforementioned LD laser source) to the waveguide of the modulator 201 in the modulator module 2 via the collimating lens 102 and the focusing lens 104. The modulator 201 in the modulator module 2 is generally a lithium niobate intensity modulator with a double-arm waveguide structure based on the MZM principle. The modulator operates under a certain DC bias, loading the light intensity with an RF signal. The detailed principle of the modulator is prior art and will not be elaborated here.

[0049] In a preferred embodiment, the laser coupling module 1 further includes an isolator 103, which is disposed between the collimating lens 102 and the focusing lens 104. That is, an isolator 103 exists between the collimating lens 102 and the focusing lens 104 to isolate reflected light and protect the LD, i.e., the laser 101. The preferred embodiment described above couples the light source into the waveguide of the modulator 201 through the laser coupling module 1, realizing the spatial light-based LD laser coupling scheme.

[0050] Continue to refer to Figure 4 In a preferred embodiment, the optical fiber assembly 3 includes an optical fiber fixing block 301 and an optical fiber 302. The core of the optical fiber 302 is aligned with the output waveguide end of the modulator 201 to achieve mode field matching, thereby coupling the modulated optical radio frequency signal into the optical fiber 302. The optical fiber 302 and the modulator 201 are fixed together by the optical fiber fixing block 301. Specifically, in the above preferred embodiment, after the radio frequency modulated optical signal is transmitted to the output waveguide end of the modulator 201, mode field matching is achieved by aligning the core of the optical fiber 302 with the output waveguide end of the modulator 201, thereby coupling the optical radio frequency signal into the optical fiber 302. Since the diameter of the optical fiber 302 is extremely small, it cannot be directly fixed to the modulator; therefore, the optical fiber fixing block 301 is used to indirectly fix the optical fiber 302 and the modulator 201.

[0051] refer to Figure 5 (Cross-sectional view of the fiber optic fixing part) In a preferred embodiment, the fiber optic fixing block 301 includes a fiber optic V-shaped seat 301a and a fiber optic cover 301b. The fiber optic 302 is clamped between the fiber optic V-shaped seat 301a and the fiber optic cover 301b, and the fiber optic 302 is bonded to the fiber optic V-shaped seat 301a and the fiber optic cover 301b by filling with adhesive. The fiber optic 302 is firmly clamped and fixed by using the flat-V structure and adhesive bonding. In a preferred embodiment, the fiber optic V-shaped bracket 301a and the fiber optic cap 301b are made of glass and have a coefficient of thermal expansion that matches that of the fiber optic cable 302. The coating on the clamped portion of the fiber optic cable 302 is removed, and the end faces of the fiber optic V-shaped bracket 301a, the fiber optic cap 301b, and the fiber optic cable 302 are made flush through grinding. When coupling and fixing the fiber optic cable 302 and the modulator 201, the fiber optic fixing block 301 and the fiber optic cable 302 are prefabricated into a single, flush-faced fiber optic assembly 3. Then, the fiber optic assembly 3 is optically coupled to align the core of the fiber optic cable 302 with the waveguide of the modulator 201. Finally, the end face of the fiber optic V-shaped bracket 301a is bonded to the non-waveguide area of ​​the side of the modulator 201 to complete the coupling and fixing of the fiber optic cable 302 and the modulator 201. The coupling of the modulator 201 and the fiber optic assembly 3 in the above preferred embodiment realizes the fiber-optic-based output scheme.

[0052] refer to Figure 6 The diagram shows the overall implementation of the RF-optical path integration. It should be noted that modulator manufacturers often design the modulator's incident and output surfaces as inclined surfaces due to parameters such as insertion loss and return loss. Considering end face refraction, the input coupling optical path of laser 101 and the output coupling point of fiber 302 are both designed with an inclined angle, which matches the end face refraction angle of the modulator.

[0053] In a preferred embodiment, the RF transmission module 4 includes an RF input head 401, a microwave matching network 402, a low-noise amplifier 403, and an equalizer 404. The RF signal to be transmitted is input from the RF input head 401 and transmitted through the microwave matching network 402. The low-noise amplifier 403 and the equalizer 404 are disposed in the microwave matching network 402 to amplify the original RF signal power. The RF input head 401, the microwave matching network 402, the low-noise amplifier 403, and the equalizer 404 are connected by a gold strip. It should be noted that the microwave matching network 402 is used to match the RF signal transmitted to the modulator 201 with the input impedance of the modulator 201 itself, improving microwave injection efficiency and reducing signal reflection. To improve the gain of the RF link, a low-noise amplifier 403 and an equalizer 404 are also present during RF signal transmission to amplify the original RF signal power. This preferred embodiment... Figure 6 The preferred embodiment employs a three-segment microwave matching network design, but it should be understood that actual implementation is not limited to this form. The RF input head 401, microwave matching network 402, low-noise amplifier 403, and equalizer 404 constitute the RF transmission module 4, which transmits the RF signal to be transmitted to the modulator 201, constructing the high-performance RF link scheme. The components of the transmission module 4 in this preferred embodiment are connected by gold strips, enabling RF modulation injection with high bandwidth, high gain, and low reflection.

[0054] refer to Figure 7In a preferred embodiment, the modulator module 2 includes a modulator 201, an RF base 202, a modulator RF load 203, a DC bias interface 204, and a PD (Photo Diode) 205. The waveguide of the modulator 201 receives the optical signal output from the laser coupling module 1 and couples the modulated optical RF signal from the output waveguide end to the optical fiber assembly 3. The DC bias interface 204 provides a certain DC bias for the modulator 201. The RF load 203 consumes residual RF signal energy at its end, preventing it from affecting the RF energy used for modulation. The PD 205 monitors the modulated optical signal leaking from the side of the modulator 201. The modulator 201, the modulator RF load 203, the DC bias interface 204, and the PD 205 are all mounted on the RF base 202. In the above design of this preferred embodiment, in order to improve the gain and dynamic range of the modulator 201 and reduce noise, an RF load 203 and a DC bias interface 204 are also provided to provide a certain DC bias for the modulator 201. To monitor the operating status of the modulator 201 in real time, a PD 205 for optical power monitoring is also provided to monitor the modulated optical signal leaking from the side of the modulator. The modulator 201, the modulator RF load 203, the DC bias interface 204, and the PD 205 are all mounted on the RF base 202 to form the modulator module 2. Specifically, in this preferred embodiment, the modulator RF load 203, the DC bias interface 204, and the PD 205 are placed on the same side of the modulator 201, with both the front and rear ends of the modulator 201 extending out of the RF base 202. The RF base 202 allows the position of the modulator 201 waveguide to match the laser coupling module 1, and also facilitates the electrical connection of the modulator 201. The modulator module 2 is designed to implement the radio frequency modulation scheme based on MZM external modulation technology, achieving low noise and large dynamic range modulation, while monitoring the modulation status in real time.

[0055] refer to Figure 8 In a preferred embodiment, the circuit module 5 includes a circuit board 501 and an electrical interface 502. The electrical interface 502 is connected to the circuit board 501 via soldering, gold wire, or gold strip. The electrical interface 502 provides external power to the internal components and provides internal operating status information to the external system. This preferred embodiment's circuit module 5, including the circuit board 501 and the electrical interface 502, is used to implement control, monitoring, and power supply functions, ensuring the module's normal operation. The electrical interface 502 is connected to the circuit board 501 via soldering, or alternatively via gold wire or gold strip.

[0056] Furthermore, considering the sealed packaging of key components, the outer casing module 6 of this preferred embodiment separates the circuit module 5 and the radio frequency optical modulation section (including the laser coupling module 1, modulator module 2, fiber optic assembly 3, radio frequency transmission module 4, etc.) vertically, as follows: Figure 9 As shown.

[0057] refer to Figure 3 , Figure 9 In a preferred embodiment, the outer casing module 6 includes a housing 601, an upper cover plate 602, and a lower cover plate 603. The housing 601 has a middle partition layer in the middle. The upper cover plate 602 and the middle partition layer of the housing 601 are connected by resistance welding to form a highly airtight sealed space, so that the radio frequency optical modulation part can be installed in the upper sealed space, thereby enabling the key components to work in a clean and reliable environment. The lower cover plate 603 is fixed to the housing 601 by screw holes (not shown in the figure). The circuit module 5 is installed in the lower space formed by the middle partition layer of the lower cover plate 603 and the housing 601.

[0058] refer to Figure 10 In a preferred embodiment, one side of the housing 601 is provided with an optical fiber tail tube 601a for extending the optical fiber 302 of the optical fiber assembly 3 and fixing it to the housing 601; the other side of the housing 601 is provided with an RF input tube 601d for mounting the RF input head 401 of the RF transmission module 4. The RF input head 401 is a connector with a standard RF interface for external RF signal input. The RF input head 401 and the RF input tube 601d are fixed by welding to ensure airtightness while satisfying RF signal connection. The bottom of the housing 601 is provided with a mounting ear 601b for connecting the module to the outside (e.g., conveniently installing the module into a downstream system with screws); the housing 601 is provided with glass-insulated pins 601c for connecting to components.

[0059] refer to Figure 11This is a cross-sectional schematic diagram of the glass-insulated PIN 601c structure in this embodiment. In a preferred embodiment, the glass-insulated PIN 601c includes a conductive PIN 100 located at the center (the conductive PIN 100 is a metal post with flat ends for gold wire bonding) and a glass insulator 200 welded to the middle portion of the conductive PIN 100 (the glass insulator 200 is a hollow glass insulator so that the conductive PIN 100 can pass through its hollow portion). The length of the PIN pin 100 is shorter than that of the conductive PIN pin 100. The glass insulating PIN pin 601c is sintered in the housing 601 through the glass insulator 200. The two ends of the conductive PIN pin 100 are flat. One end is located in the sealed space at the top of the housing 601 (i.e., the upper layer where the radio frequency optical modulation part is located), and the other end is located in the lower space of the housing 601 (i.e., the lower layer where the circuit module 5 is located), so that the two ends are respectively bonded to the components to be connected by gold wire, ensuring that the upper and lower layers are airtightly isolated while realizing electrical connection.

[0060] In this preferred embodiment, the internal design and packaging process of the outer casing module 6 achieve the high hermeticity optical packaging solution, typically enabling the hermeticity of the radio frequency optical modulation section to reach 1×10⁻⁶. -8 Pa·m 3 / s or more.

[0061] Additionally, refer to Figure 3 , Figure 6 In this preferred embodiment, the microwave matching network 402 of the RF transmission module 4 is designed with a multi-segment curved shape. Preferably, this embodiment uses a horizontal structure and vertical structures running in the same direction at both ends. When the RF input head 401 receives an RF signal, it first passes through the first vertical structure, then the horizontal structure, and finally the last vertical structure before reaching the modulator 201. Correspondingly, refer to... Figure 9 In the housing module 6, the intermediate spacer layer 601e of the housing 601 has a mounting step 601f at one end near the RF input tube 601d. The mounting step 601f has two steps. The lower step is provided with glass-insulated pins 601c for connecting the upper and lower layers and connecting with other components. The higher step is used to arrange the microwave matching network 402 of the RF transmission module 4. Figure 9 This is a sectional view, so the microwave matching network 402 is only shown in part on the cut step; other parts are not shown. (See reference...) Figure 12The microwave matching network 402 is arranged on the higher step of the mounting step 601f. After passing through the first vertical structure, the second horizontal structure, and the last vertical structure, it enters the modulator module 2. The design of the mounting step 601f can avoid mutual interference between components and make better use of space. The above design can save internal space and shorten the overall length of the module, so as to achieve the purpose of miniaturization, compact structure, and high integration of the equipment.

[0062] The high-performance radio frequency modulation optical emission module described in this invention is schematically a single-channel working module, but in practice, multi-channel modules can also be implemented side by side.

[0063] In summary, this invention constructs a highly reliable and high-performance radio frequency modulation optical module by employing a spatial light-based LD laser coupling scheme, a lithium niobate modulator-based RF external modulation scheme, an optical fiber-based output scheme, a hermetically sealed optical packaging scheme, and a high-performance RF connection scheme. This module meets a wide range of long-distance RF transmission needs. Furthermore, its ingenious structural design results in a compact and space-saving design, satisfying current requirements for device miniaturization and high integration.

[0064] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention. Contents not described in detail in this specification are prior art known to those skilled in the art.

Claims

1. A high-performance radio frequency modulated optical transmitting module, characterized in that, The device includes a radio frequency (RF) optical modulation section, a circuit module (5), and a housing module (6). The RF optical modulation section includes a laser coupling module (1), a modulator module (2), an optical fiber assembly (3), and an RF transmission module (4). The laser coupling module (1) is used to output an optical signal and couple the output optical signal to the modulator module (2). The modulator module (2) is used to perform RF modulation on the optical signal and couple the modulated optical carrier RF signal to the optical fiber assembly (3). The RF transmission module (4) is used to transmit RF signals to the modulator module (2). The circuit module (5) is used to implement control, monitoring, and power supply functions. The housing module (6) is used to separate the circuit module (5) and the RF optical modulation section and to seal and encapsulate the RF optical modulation section. The radio frequency transmission module (4) includes a radio frequency input head (401), a microwave matching network (402), a low noise amplifier (403), and an equalizer (404). The radio frequency signal to be transmitted is input from the radio frequency input head (401) and transmitted through the microwave matching network (402). The low noise amplifier (403) and the equalizer (404) are disposed in the microwave matching network (402) to amplify the power of the original radio frequency signal. The radio frequency input head (401), the microwave matching network (402), the low noise amplifier (403), and the equalizer (404) are connected by a gold strip. Among them, the microwave matching network (402) is designed as a multi-segment curved shape. The microwave matching network (402) consists of a horizontal structure and vertical structures in the same direction at both ends. When the radio frequency input head (401) inputs the radio frequency signal, it first passes through the first vertical structure, then through the horizontal structure, and finally through the last vertical structure before reaching the modulator (201). The low noise amplifier (403) is set between the first vertical structure and the horizontal structure, and the equalizer (404) is set between the horizontal structure and the last vertical structure.

2. The high-performance radio frequency modulated optical transmitting module according to claim 1, characterized in that, The laser coupling module (1) includes a laser (101), a collimating lens (102) and a focusing lens (104), wherein the constant power laser output by the laser (101) is coupled into the waveguide of the modulator module (2) after passing through the collimating lens (102) and the focusing lens (104) in sequence.

3. The high-performance radio frequency modulated optical transmitting module according to claim 2, characterized in that, The laser coupling module (1) further includes an isolator (103), which is disposed between the collimating lens (102) and the focusing lens (104) to isolate the reflected light.

4. The high-performance radio frequency modulated optical transmitting module according to claim 1, characterized in that, The modulator module (2) includes a modulator (201), an RF base (202), a modulator RF load (203), a DC bias interface (204), and a PD (205). The waveguide of the modulator (201) is used to receive the optical signal output by the laser coupling module (1) and to couple the modulated optical carrier RF signal from the output waveguide end to the optical fiber assembly (3). The modulator RF load (203) is used to consume residual RF signal energy. The DC bias interface (204) provides a certain DC bias for the modulator (201). The PD (205) is used to monitor the modulated optical signal leaked from the side of the modulator (201). The modulator (201), the modulator RF load (203), the DC bias interface (204), and the PD (205) are all mounted on the RF base (202).

5. The high-performance radio frequency modulated optical transmitting module according to claim 4, characterized in that, The optical fiber assembly (3) includes an optical fiber fixing block (301) and an optical fiber (302). The core of the optical fiber (302) and the output waveguide end of the modulator (201) are aligned to achieve mode field matching so as to couple the modulated optical radio frequency signal into the optical fiber (302). The optical fiber (302) and the modulator (201) are fixed together by the optical fiber fixing block (301).

6. The high-performance radio frequency modulated optical transmitting module according to claim 5, characterized in that, The optical fiber fixing block (301) includes an optical fiber V-shaped seat (301a) and an optical fiber cover (301b). The optical fiber (302) is clamped between the optical fiber V-shaped seat (301a) and the optical fiber cover (301b), and the optical fiber (302) is bonded to the optical fiber V-shaped seat (301a) and the optical fiber cover (301b) by filling with adhesive.

7. The high-performance radio frequency modulated optical transmitting module according to claim 6, characterized in that, The fiber V-shaped seat (301a) and the fiber cap (301b) are made of glass and have a thermal expansion coefficient that matches that of the fiber (302). The coating of the clamped portion of the fiber (302) is stripped off, and the end faces of the fiber V-shaped seat (301a), the fiber cap (301b), and the fiber (302) are made flush by grinding. When coupling and fixing the fiber (302) and the modulator (201), the fiber fixing block (301) and the fiber (302) are prefabricated into a single fiber assembly (3) with flush end faces. Then, the fiber assembly (3) is optically coupled so that the core of the fiber (302) is aligned with the waveguide of the modulator (201). Finally, the end face of the fiber V-shaped seat (301a) is bonded to the non-waveguide area on the side of the modulator (201) to complete the coupling and fixing of the fiber (302) and the modulator (201).

8. The high-performance radio frequency modulated optical transmitting module according to any one of claims 1-7, characterized in that, The circuit module (5) includes a circuit board (501) and an electrical interface (502). The electrical interface (502) is connected to the circuit board (501) by one or more of soldering, gold wire, and gold strip. The electrical interface (502) provides external power to the internal components and provides internal working status information to the external components.

9. The high-performance radio frequency modulated optical transmitting module according to any one of claims 1-7, characterized in that, The outer casing module (6) includes a housing (601), an upper cover plate (602), and a lower cover plate (603). A middle spacer is provided in the middle of the housing (601). A highly airtight sealed space is formed between the upper cover plate (602) and the middle spacer of the housing (601) using resistance welding, so that the radio frequency modulation section is installed in the upper sealed space. The lower cover plate (603) is fixed to the housing (601). The circuit module (5) is installed in the lower space formed by the middle spacer between the lower cover plate (603) and the housing (601). An optical fiber tail tube (601a) is provided on one side of the housing (601) for extending the optical fiber (302) of the optical fiber assembly (3). An radio frequency input tube (601d) is provided on the other side of the housing (601) for installing the radio frequency input head (40) of the radio frequency transmission module (4). 1) The bottom of the tube shell (601) is provided with mounting ear (601b) for connecting the module to the outside; the tube shell (601) is provided with glass insulating pin (601c), the glass insulating pin (601c) includes a conductive pin (100) located in the center and a glass insulator (200) welded to the middle part of the conductive pin (100). The length of the glass insulator (200) is shorter than the length of the conductive pin (100). The glass insulating pin (601c) is sintered in the tube shell (601) through the glass insulator (200). The two ends of the conductive pin (100) are flat. One end is located in the sealed space in the upper part of the tube shell (601), and the other end is located in the lower part of the tube shell (601) so as to be bonded to the components that need to be connected by gold wire respectively.

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