A high-frequency electro-optic modulator integrated with microwave amplification function

Abstract

This invention relates to a high-frequency electro-optic modulator integrating microwave amplification, comprising a microwave amplification unit, an electro-optic modulation unit, and a metal housing. The electro-optic modulator operates in the 42GHz~53GHz frequency band. This invention integrates high-frequency microwave signal amplification and electro-optic modulation within a single module, meeting the application requirements of high-frequency microwave photonic transmission. This invention heterogeneously integrates components such as a low-noise amplifier chip, an electro-optic modulator chip, and a backlight detection chip within the same metal housing. The components are electrically interconnected using microstrip lines, gold wire bonding, and other processes. Optical signals are input and output via fiber optic components, while radio frequency signals are fed in via radio frequency components, forming a highly reliable hermetically sealed structure. This invention can amplify weak high-frequency microwave signals and then perform electro-optic modulation before output, offering significant advantages in operating frequency band, radio frequency gain, lightweight design, and reliability.

Description

Technical Field

[0001] This invention belongs to the field of microwave photonics technology, specifically relating to a high-frequency electro-optic modulator with integrated microwave amplification function. Background Technology

[0002] Microwave photonics is an interdisciplinary science that combines photonics and microwave technology. Its core idea is to use light waves as a carrier to distribute, convert, process, and transmit radio frequency signals. Traditional electronic systems directly convert the frequency of radio frequency signals in the electrical domain, while microwave photonics first modulates the microwave signal onto an optical wave, performs frequency conversion in the optical domain, and then converts it back to an electrical signal. Microwave photonics leverages the high speed, high bandwidth, low loss, and electromagnetic interference resistance of light to effectively overcome the bottlenecks encountered by pure electronic technology in processing high-frequency microwave signals, and has significant application value in many fields such as laser communication, radar systems, and electronic warfare.

[0003] The electro-optic modulator module is a core component of a microwave photonic transmission system. Its main function is to modulate the input radio frequency (RF) signal onto an optical carrier and output it. To achieve the optimal output signal-to-noise ratio (SNR), the input RF signal strength is typically required to be ≥10 dBm. However, in certain specific applications, the RF signal power is very weak. For example, a typical spaceborne microwave photonic communication system receives a microwave signal with a power of -50 dBm, which generally requires a low-noise amplifier module to amplify the signal by a certain factor before inputting it to the electro-optic modulator. This type of microwave photonic transmission system, constructed from multiple discrete components, RF connectors, optical fibers, etc., suffers from drawbacks such as large size, high weight, and poor stability. The maximum operating frequency of the system is less than 40 GHz, making it difficult to meet the requirements of high-frequency applications. Therefore, high-frequency, integrated, and lightweight designs have become important development directions for microwave photonics technology. Summary of the Invention

[0004] The purpose of this invention is to provide a high-frequency electro-optic modulator with integrated microwave amplification function, characterized by high gain, high frequency band, integration, and high reliability. This electro-optic modulator heterogeneously integrates radio frequency components, low-noise amplifier chips, and electro-optic modulator chips in the same module, realizing microwave amplification and electro-optic modulation functions. Its operating frequency band is 42~53GHz, which can meet the application requirements of high-frequency microwave photonic transmission.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A high-frequency electro-optic modulator integrating microwave amplification function includes: a microwave amplification unit, an electro-optic modulation unit, and a metal housing. The high-frequency electro-optic modulator operates in the frequency band of 42GHz to 53GHz. Each high-frequency signal node between the microwave amplification unit and the modulation unit is connected by a parallel bonded arched wire structure with a height of less than 150μm and a length of less than 150μm using double gold wires to reduce high-frequency parasitic inductance.

[0006] The microwave amplification unit includes a low-noise amplifier circuit, a microstrip line, and a ceramic substrate installed inside a metal housing, as well as a radio frequency component installed outside the metal housing with its output end extending into the metal housing; the low-noise amplifier circuit and the microstrip line are both disposed on the ceramic substrate.

[0007] The electro-optic modulation unit includes an electro-optic modulator chip, an impedance matching component, a backlight detection chip, and an optical fiber assembly. The electro-optic modulator chip, the backlight detection chip, and the impedance matching component are all encapsulated inside the metal housing. The electro-optic modulator chip is electrically interconnected with the low-noise amplifier circuit via a microstrip line. The backlight detection chip is signal-connected to the electro-optic modulator chip. The impedance matching component is connected between the electro-optic modulator chip and the metal housing to achieve RF characteristic impedance matching in the 42GHz~53GHz frequency band. The optical fiber assembly passes through the metal housing and is optically coupled to the electro-optic modulator chip.

[0008] Specifically, the low-noise amplifier circuit is electrically interconnected with the microwave signal input port of the electro-optic modulator chip via a microstrip line, forming a high-frequency transmission path with low parasitic inductance; the optical fiber assembly passes through the metal housing and is optically coupled to the electro-optic modulator chip.

[0009] Furthermore, the low-noise amplifier circuit includes two stages of low-noise amplifier chips and an attenuator chip. The two stages of low-noise amplifier chips are a first-stage low-noise amplifier chip and a second-stage low-noise amplifier chip, respectively; the attenuator chip is disposed between the two stages of low-noise amplifier chips and is used to suppress high-frequency cavity reflections and self-excited oscillations caused by high-gain amplification in the 42GHz~53GHz frequency band.

[0010] The output terminal of the radio frequency component extends into the metal housing and is connected to the input terminal of the first-stage low-noise amplifier chip via a microstrip line. The output terminal of the first-stage low-noise amplifier chip is connected to the input terminal of the attenuator chip via a microstrip line. The output terminal of the attenuator chip is connected to the input terminal of the second-stage low-noise amplifier chip via a microstrip line. The output terminal of the second-stage low-noise amplifier chip is connected to the input terminal of the electro-optic modulator chip via a microstrip line.

[0011] Furthermore, the low-noise amplifier chip and attenuator chip are mounted on the surface of the ceramic substrate and connected to the metal casing through the grounding via on the back of the ceramic substrate; both low-noise amplifier chips adopt a single power supply mode.

[0012] Furthermore, the ceramic substrate is an aluminum nitride ceramic substrate; the conductor material of the microstrip line is a Ti / Pt / Au thin film composite metal layer, with a total transmission path loss of less than 2dB and a voltage standing wave ratio of less than 1.8 in the 42GHz~53GHz frequency band.

[0013] Furthermore, the radio frequency component includes a housing and radio frequency terminals, the interface of which adopts a standard SMA connector and the transmission frequency range covers 42GHz~53GHz; the housing is fixed to the side wall of the metal housing by a threaded structure, the radio frequency terminals are soldered to the metal housing by a gold-tin soldering process, and the inner core of the radio frequency terminals is soldered to the microstrip line.

[0014] Furthermore, the impedance matching component includes an impedance matching substrate and an impedance matching circuit disposed on the surface of the impedance matching substrate; the impedance matching substrate is made of aluminum nitride material, and the impedance matching circuit is formed on its surface by a thin film etching process; one end of the impedance matching component is connected to the impedance matching port of the electro-optic modulator chip by gold wire bonding, and the other end is connected to the ground terminal of the metal shell, so that the RF characteristic impedance of the system in the 42GHz~53GHz frequency band is kept at around 50Ω.

[0015] Furthermore, the electrical connection points of the high-frequency electro-optic modulator are connected by a gold wire bonding process.

[0016] Furthermore, the electro-optic modulator chip is a waveguide folded thin-film lithium niobate electro-optic modulator chip, which is provided with an optical input port, an optical output port, a backlight detection grating, a microwave signal input port, an impedance matching port, and a bias control port, for electro-optic modulation of optical signals in the 1530nm~1570nm band.

[0017] The optical input port, optical output port and optical fiber assembly are connected by optical coupling process; the backlight detection grating is connected to the photosensitive surface of the backlight detection chip; the microwave signal input port is electrically connected to the microstrip line by gold wire bonding process; the impedance matching port is connected to the impedance matching component by gold wire bonding process, and the other end of the impedance matching component is connected to the metal housing; the bias control port is electrically connected to the through-hole insulated pin of the metal housing by bonding gold wire.

[0018] Furthermore, the optical fiber assembly includes an input optical fiber and an output optical fiber arranged in parallel with each other; the ends of the input optical fiber and the output optical fiber are each integrated with a mode field diameter conversion structure that converts the mode field diameter from 9μm to 4μm, for low-loss coupling with the 4μm mode field diameter waveguide end face of the electro-optic modulator chip.

[0019] Furthermore, the optical fiber assembly is fitted with a metallized gold-plated nickel tube through the outside of the metal housing, and the metallized gold-plated nickel tube is welded and sealed to the metal housing.

[0020] Compared with the prior art, the present invention has the following beneficial effects: This invention integrates high-frequency microwave signal amplification and electro-optic modulation into a single module, eliminating the need for a separate microwave amplifier and meeting the requirements of microwave photonic transmission in the 42GHz~53GHz high-frequency band. The invention heterogeneously integrates components such as a low-noise amplifier chip, an electro-optic modulator chip, and a backlight detection chip within a metal housing. Electrical interconnection between the devices is achieved through microstrip lines and gold wire bonding. Optical signals are input and output via fiber optic assemblies. The RF and optical interfaces are sealed to the metal housing through welding, forming a highly reliable hermetically sealed package. This invention first performs low-noise amplification within the tube for weak high-frequency microwave signals before electro-optic modulation and output. A cascaded attenuator between the two stages of low-noise amplifiers suppresses cavity reflections and self-oscillations in the high-frequency link. Simultaneously, a broadband impedance matching component reduces RF reflection losses in the millimeter-wave band. Compared to existing technologies, this invention offers significant advantages in operating frequency band, gain, lightweight design, and reliability, making it particularly suitable for spaceborne and airborne microwave photonic and laser communication scenarios. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the laser communication signal transmitter frame; Figure 2 This is a schematic diagram showing the connection between a traditional lithium niobate electro-optic modulator and a low-noise amplifier. Figure 3 This is a schematic diagram of the high-frequency electro-optic modulator integrating microwave amplification function in this invention. Figure 4 This is a physical image of the high-frequency electro-optic modulator that integrates microwave amplification function in this invention.

[0022] in: 1. Electro-optic modulator chip, 2. Low-noise amplifier chip, 3. Microstrip line, 4. Radio frequency components, 5. Attenuator chip, 6. Impedance matching substrate, 7. Backlight detection chip, 8. Metal housing, 9. Fiber optic components. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings: High-speed communication satellites typically employ laser communication technology to transmit information between satellites and ground stations or between satellites. The frame of the signal transmitter in laser communication is as follows: Figure 1 As shown. The function of the electro-optic modulator is to modulate high-frequency electrical signals onto an optical carrier and transmit them, while the function of the low-noise amplifier is to amplify weak radio frequency electrical signals to a range that the electro-optic modulator can handle. The two are interconnected through radio frequency cables.

[0024] A schematic diagram of the connection between a traditional lithium niobate electro-optic modulator and a low-noise amplifier is shown below. Figure 2As shown. Due to the limitations of the manufacturing process of bulk lithium niobate materials, the modulation bandwidth of traditional lithium niobate electro-optic modulators is difficult to exceed 40GHz. Furthermore, their linear waveguide design makes them inflexible and unsuitable for miniaturization and integration, failing to meet the requirements of high-frequency microwave photonic transmission scenarios. In practice, weak radio frequency signals must first be amplified by a low-noise amplifier module, which undoubtedly adds to their size and weight. In space launches where weight is measured precisely in grams, effective control of the weight and volume of each module is crucial. In recent years, with the rapid development of commercial space satellites, the shortcomings of traditional bulk lithium niobate (LiNbO3) modulators—large size, high driving voltage, and limited bandwidth—have become increasingly apparent, making it difficult to meet the stringent size, weight, and power consumption (SWaP) requirements of space payloads. Additionally, the large size of the low-noise amplifier and its associated cables is also a major obstacle to lightweight space payloads.

[0025] To address the aforementioned shortcomings, this invention proposes a high-frequency electro-optic modulator integrating microwave amplification. This device can simultaneously amplify and electro-optically modulate microwave signals within a specific frequency band. The main specifications of the device are as follows: operating frequency band of 42GHz~53GHz, operating wavelength of 1530nm~1570nm, RF amplification factor of 35dB, and input 1dB compression power of -20dBm. This high-frequency electro-optic modulator employs a multi-chip heterogeneous integration process, combined with an integrated metal housing structure for hermetic packaging. Microstrip lines are specially designed between chips to achieve high-frequency signal interconnection, and various bare chips utilize gold wire bonding technology for electrical power supply and signal interconnection. The high-frequency electro-optic modulator described in this invention has advantages such as lightweight design, integration, large bandwidth, and high reliability, and can meet the application requirements of laser communication, microwave photonic frequency conversion, and high-frequency photonic transmission.

[0026] like Figure 3 As shown, the high-frequency electro-optic modulator with integrated microwave amplification function includes: a microwave amplification unit, an electro-optic modulation unit, and a metal housing 8. The operating frequency band of the high-frequency electro-optic modulator is 42GHz~53GHz.

[0027] This invention designs a complete microwave amplification and electro-optic modulation module. Each component is specifically designed for microwave signals in the 42-53 GHz frequency band, effectively avoiding self-excitation, oscillation, distortion, and leakage of microwave signals, and efficiently completing the amplification and modulation of weak microwave signals. The metal housing 8 has external dimensions of 35mm × 10mm × 9mm, with a compact and small structure. All connecting lines or interfaces are in the same direction, reducing the space required when assembling multiple modules in an array. This invention effectively solves the problem of integrating weak signal amplification and electro-optic modulation functions, meeting the requirements of modern laser communication fields for high bandwidth, lightweight, and integrated electro-optic modulators.

[0028] According to a preferred embodiment of the present invention, the microwave amplification unit includes a low-noise amplifier circuit, a radio frequency component 4, a microstrip line 3, and a ceramic substrate. The ceramic substrate is installed inside a metal housing 8, the low-noise amplifier circuit is bonded and fixed to the surface of the ceramic substrate, and the microstrip line is laid on the surface of the ceramic substrate.

[0029] According to a preferred embodiment of the present invention, considering that achieving high-gain (>35dB) amplification within a very small metal cavity is prone to high-frequency electromagnetic wave reflection and self-oscillation, the low-noise amplifier circuit in this embodiment specifically adopts a three-stage cascaded physical structure consisting of a first-stage low-noise amplifier chip, an attenuator chip 5, and a second-stage low-noise amplifier chip. The low-noise amplifier circuit is installed inside a metal housing 8, and the radio frequency component 4 is installed outside the metal housing 8. The output terminal of the radio frequency component 4 extends into the metal housing 8 and is connected to the input terminal of the first-stage low-noise amplifier chip via a microstrip line. The output terminal of the first-stage low-noise amplifier chip is connected to the input terminal of the attenuator chip via a microstrip line. The output terminal of the attenuator chip 5 is connected to the input terminal of the second-stage low-noise amplifier chip via a microstrip line, and the output terminal of the second-stage low-noise amplifier chip is connected to the radio frequency input terminal of the electro-optic modulator chip 1 via a microstrip line.

[0030] According to a preferred embodiment of the present invention, both the low-noise amplifier chip 2 and the attenuator chip 5 are mounted on the surface of a ceramic substrate inside a metal housing 8 as bare chips, with the back of the chips directly grounded to the metal housing 8 through through-holes in the substrate. The operating frequency range of the low-noise amplifier chip 2 and the attenuator chip 5 covers 42GHz~53GHz, with a linear gain of 20dB for a single low-noise amplifier chip 2 and an output compression power of 15dBm for 1dB. The intermediately integrated attenuator chip 5 (such as a 3dB / 6dB thin-film attenuator chip) can effectively absorb interstage standing waves and cavity parasitic feedback between the two amplifier stages, flatten the in-band gain, and completely eliminate self-oscillation. The amplified microwave signal output from the second-stage low-noise amplifier chip 2 is directly fed into the microwave signal input port of the electro-optic modulator chip through ultra-short dual gold wire parallel bonding (arch wire height <150μm, length <150μm), greatly reducing interconnect parasitic inductance.

[0031] According to a preferred embodiment of the present invention, the transmission frequency range of the microstrip line 3 covers 42GHz to 53GHz, with a total transmission loss of no more than 2dB and a voltage standing wave ratio of no more than 1.8. The substrate material of the microstrip line 3 is aluminum nitride ceramic. The conductor layer of the microstrip line 3 is made of Ti / Pt / Au composite metal thin film, which can achieve extremely low high-frequency transmission loss.

[0032] According to a preferred embodiment of the present invention, the radio frequency component 4 includes a housing and radio frequency terminals, the interface adopts a standard SMA connector, and the transmission frequency range covers 42GHz~53GHz. The housing of the radio frequency component 4 is connected to the metal housing 8 through a threaded structure, and the radio frequency terminals are soldered to the metal housing 8 using a gold-soldering process. The inner end of the radio frequency terminals is electrically connected to the microstrip line 3.

[0033] According to a preferred embodiment of the present invention, the electro-optic modulation unit includes an electro-optic modulator chip 1, an impedance matching component, a backlight detection chip 7, and an optical fiber assembly 9. The electro-optic modulator chip 1, the backlight detection chip 7, and the impedance matching component are the core components of the modulation unit and are arranged inside the metal housing 8. The optical fiber assembly 9 passes through the metal housing 8 and is optically coupled to the electro-optic modulator chip 1. The electro-optic modulator chip 1 completes the input and output of optical signals through the optical fiber assembly 9. The backlight detection chip 7 is signal-connected to the electro-optic modulator chip 1; the impedance matching component is electrically connected to both the electro-optic modulator chip 1 and the metal housing 8.

[0034] According to a preferred embodiment of the present invention, in order to achieve excellent 50Ω impedance matching and absorb unconsumed radio frequency energy at high frequencies of 42GHz to 53GHz, the impedance matching port of the electro-optic modulator chip 1 is connected to an impedance matching component via gold wire bonding. The impedance matching component includes an impedance matching substrate 6 and an impedance matching circuit disposed on the surface of the impedance matching substrate 6. The impedance matching substrate 6 is made of aluminum nitride material, and its surface is formed by thin-film etching to create a thin-film absorption resistor and conductive band to form the impedance matching circuit. One end of the impedance matching component is connected to the electro-optic modulator chip 1 via gold wire bonding, and the other end is connected to the metal housing 8, making the characteristic impedance of the entire module 50Ω, achieving low-loss absorption and low-reflection.

[0035] According to a preferred embodiment of the present invention, the impedance matching substrate 6 is made of aluminum nitride material, and the substrate surface is fabricated with matching conductive strips and thin film resistors using a thin film etching process; the two ends of the conductive strips are respectively connected to the electro-optic modulator chip 1 and the metal housing 8, thereby achieving impedance matching and reducing reflection loss during microwave signal transmission.

[0036] According to a preferred embodiment of the present invention, the electrical connection points of the high-frequency electro-optic modulator are connected by a gold wire bonding process.

[0037] According to a preferred embodiment of the present invention, the electro-optic modulator chip 1 is a waveguide folded thin-film lithium niobate (TFLN) electro-optic modulator chip, which has a high electro-optic coefficient and an extremely small half-wave voltage. The electro-optic modulator chip 1 is provided with an optical input port, an optical output port, a backlight detection grating, a microwave signal input port, an impedance matching port, and a bias control port, for electro-optic modulation of optical signals in the 1530nm~1570nm wavelength band. The optical input port, optical output port, and optical fiber assembly 9 are precisely aligned through optical coupling technology to achieve efficient optical interconnection. The backlight detection grating is connected to the photosensitive surface of the backlight detection chip 7. The microwave signal input port is electrically connected to the microstrip line 3 through gold wire bonding. The impedance matching port is connected to the impedance matching substrate 6 through gold wire bonding, and the other end of the impedance matching substrate 6 is connected to the metal housing 8. The bias control port is connected to an external pin of the metal housing 8 through gold wire bonding, and the external control voltage controls the operating state of the electro-optic modulator chip 1 through this pin to ensure that the device is at the target modulation operating point.

[0038] According to a preferred embodiment of the present invention, the backlight detection chip 7 is aligned and disposed above the backlight detection grating of the electro-optic modulator chip 1. The backlight detection chip 7 is a photodiode with an operating wavelength covering 1530nm~1570nm, an electro-optic responsivity greater than 0.8A / W, a dark current less than 10nA, and an input saturation light power greater than 10mW. The backlight detection chip 7 receives the optical signal emitted by the grating of the electro-optic modulator chip 1 and linearly converts the optical signal into a current signal for output. The backlight detection chip 7 absorbs a small portion of leaked light in real time and converts it into an induced current, which is output to an external bias control circuit through the housing pins to lock the optimal operating point of the modulator in real time.

[0039] According to a preferred embodiment of the present invention, the metal housing 8 is used to effectively support all functional components, and the whole adopts an integrated hermetically sealed design. All optical and electrical interfaces are connected internally and externally through welding processes.

[0040] According to a preferred embodiment of the present invention, the optical fiber assembly 9 includes two optical fibers, an input fiber and an output fiber, used for optical input and optical output, respectively. The optical mode field diameter of the optical input / output port of the electro-optic modulator chip 1 is 4 μm, while the optical mode field diameter of the optical fiber assembly is 9 μm. Since their mode field sizes are mismatched, this embodiment designs a 9 μm to 4 μm mode conversion structure at the port of the optical fiber assembly 9, achieving low-loss alignment and coupling between the optical fiber assembly and the end face of the electro-optic modulator chip. Furthermore, to ensure a hermetically tight structure, a gold-plated nickel tube is fitted around the portion of the optical fiber assembly 9 that passes through the metal housing 8. The gold-plated nickel tube is laser-bonded to the metal housing 8 for sealing and fixation, ensuring the hermetically tight performance of the module. Combined with the gold-tin soldering of the RF assembly 4 and the parallel seam welding of the metal housing cover plate, the entire high-frequency electro-optic modulator achieves highly reliable hermetically sealed packaging with a leakage rate of less than [missing value]. It fully meets the high and low temperature and long-term aging reliability requirements of the space environment.

[0041] like Figure 1 As shown, the working principle of the high-frequency electro-optic modulator with integrated microwave amplification function described in this invention is as follows: An external low-power microwave signal is input to the high-frequency electro-optic modulator via RF component 4. The microwave signal is amplified by a specific factor by low-noise amplifier chip 2. Attenuator chip 5 effectively suppresses the self-excitation effect of the microwave signal during transmission, ensuring the quality of microwave signal transmission. Microstrip line 3 serves as the transmission carrier for the microwave signal, inputting the amplified microwave signal to the RF port of electro-optic modulator chip 1. Fiber optic component 9 includes input and output fibers, used for optical carrier input and modulated signal light output, respectively. Electro-optic modulator chip 1 modulates the amplified microwave signal onto the optical carrier, outputting signal light carrying microwave information. Backlight detection chip 7 is used to detect the modulation state of electro-optic modulator chip 1 in real time using the electro-optic effect and outputs the corresponding induced current, facilitating external circuit locking of the module's operating point. In addition, electro-optic modulator chip 1 is connected to an impedance matching component, which is connected to the metal housing 8, matching the RF characteristic impedance of the entire module to approximately 50Ω, reducing high-frequency signal reflection loss.

[0042] The high-frequency electro-optic modulator with integrated microwave amplification proposed in this invention operates at frequencies from 42 GHz to 53 GHz. Directly "splitting" the electro-optic modulator and low-noise amplifier will result in severe impedance mismatch, excessive insertion loss, and signal resonance distortion. This is because when the transmission signal frequency exceeds GHz, the design of related circuits no longer considers "lumped circuits" but rather "distributed transmission systems." The design of the transmission signal enters the operating region dominated by electromagnetic wave propagation, and the analysis basis transitions from traditional circuit theory to Maxwell's electromagnetic field theory. The bond wires, pads, and vias inside the module will exhibit significant parasitic inductance and capacitance. During design, it is necessary to model based on S-parameters and comprehensively consider RF indicators such as impedance matching, insertion loss (S21), and group delay to ultimately form a structural model adapted to the 42 GHz to 53 GHz frequency band.

[0043] The high-frequency electro-optic modulator integrating microwave amplification function in this invention is shown in the following physical example. Figure 4 As shown in Table 1, the measured data of key performance indicators of the traditional discrete scheme and the high-frequency electro-optic modulator with integrated microwave amplification function described in this invention are compared.

[0044] Table 1 Comparison of Indicators

[0045] As shown above, this invention heterogeneously integrates the low-noise amplifier chip, thin-film attenuator, thin-film lithium niobate modulation chip, and backlight detection chip into a compact 30mm×10mm×9mm metal housing, completely eliminating the bulky RF coaxial cables and connectors between discrete modules. The overall weight is reduced to approximately 35g (more than 65% lighter than traditional discrete solutions), greatly meeting the stringent SWaP requirements of commercial satellites and aerospace applications. This invention directly interconnects the low-noise amplifier chip and the thin-film lithium niobate chip within the housing via ultra-short double gold wire bonding and high-frequency microstrip lines, replacing the traditional coaxial transition and minimizing the equivalent parasitic inductance at the connection point. Combined with an aluminum nitride (AlN) impedance matching substrate and a high-frequency thin-film absorption circuit, signal reflection and standing wave degradation in the 42GHz~53GHz high-frequency band are eliminated. This invention cleverly integrates a thin-film attenuator chip between two low-noise amplifier chips. Combined with the electromagnetic shielding isolation inside the metal casing and the multi-hole grounding design on the back, it effectively isolates the positive feedback path caused by high-gain amplification in the millimeter-wave band, and completely solves the industry problem of self-excited oscillation in high-gain (>35dB) circuits in a very small space of a micro cavity.

[0046] In summary, this invention organically integrates various components into a complete module. By optimizing the operating frequency bands of each component, it achieves highly efficient integration of weak microwave signal amplification and electro-optic modulation functions, thus realizing integrated innovation based on traditional electro-optic modulation principles. The collaborative optimization of the components in the electro-optic modulator described in this invention may result in a smaller performance degradation and significantly higher reliability than expected during long-term operation. It possesses outstanding advantages in terms of small size, lightweight design, and high-frequency operation that traditional electro-optic modulators or microwave amplifiers cannot match.

[0047] The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A high-frequency electro-optic modulator integrating microwave amplification function, characterized in that, include: The microwave amplification unit, the electro-optic modulation unit and the metal housing (8) are used in the high-frequency electro-optic modulator, which operates in the frequency band of 42GHz~53GHz. The microwave amplification unit includes a low-noise amplifier circuit, a microstrip line (3), and a ceramic substrate installed inside a metal housing, as well as a radio frequency component (4) installed outside the metal housing (8) with its output end extending into the interior of the metal housing (8); the low-noise amplifier circuit and the microstrip line (3) are both disposed on the ceramic substrate; The electro-optic modulation unit includes an electro-optic modulator chip (1), an impedance matching component, a backlight detection chip (7), and an optical fiber component (9); the electro-optic modulator chip (1), the backlight detection chip (7), and the impedance matching component are all encapsulated inside the metal housing (8); the backlight detection chip (7) is signal-connected to the electro-optic modulator chip (1); the electro-optic modulator chip (1) is electrically interconnected with the low-noise amplifier circuit through a microstrip line (3); the impedance matching component is connected between the impedance matching port of the electro-optic modulator chip (1) and the metal housing (8) to achieve RF characteristic impedance matching in the 42GHz~53GHz frequency band; the optical fiber component (9) passes through the metal housing (8) and is optically coupled to the electro-optic modulator chip (1).

2. The high-frequency electro-optic modulator with integrated microwave amplification function according to claim 1, characterized in that, The low-noise amplifier circuit includes two stages of low-noise amplifier chips (2) and an attenuator chip (5); the two stages of low-noise amplifier chips (2) are the first stage low-noise amplifier chip and the second stage low-noise amplifier chip, respectively; the attenuator chip (5) is disposed between the two stages of low-noise amplifier chips (2) and is used to suppress high-frequency cavity reflection and self-excited oscillation caused by high-gain amplification in the 42GHz~53GHz frequency band. The output end of the radio frequency component (4) extends into the metal housing (8) and is connected to the input end of the first-stage low-noise amplifier chip via a microstrip line (3); the output end of the first-stage low-noise amplifier chip is connected to the input end of the attenuator chip via a microstrip line (3); the output end of the attenuator chip (5) is connected to the input end of the second-stage low-noise amplifier chip via a microstrip line (3); and the output end of the second-stage low-noise amplifier chip is connected to the input end of the electro-optic modulator chip (1) via a microstrip line (3).

3. The high-frequency electro-optic modulator with integrated microwave amplification function according to claim 2, characterized in that, The low-noise amplifier chip (2) and the attenuator chip (5) are mounted on the surface of the ceramic substrate and connected to the metal casing through the grounding through hole on the back of the ceramic substrate; both low-noise amplifier chips (2) adopt a single power supply mode.

4. The high-frequency electro-optic modulator with integrated microwave amplification function according to claim 1, characterized in that, The ceramic substrate is an aluminum nitride ceramic substrate; The conductive material of the microstrip line (3) is a Ti / Pt / Au thin film composite metal layer.

5. The high-frequency electro-optic modulator with integrated microwave amplification function according to claim 1, characterized in that, The radio frequency component (4) includes a housing and a radio frequency terminal. Its interface adopts a standard SMA connector and the transmission frequency range covers 42GHz~53GHz. The housing is fixed to the side wall of the metal housing (8) by a threaded structure. The radio frequency terminal is soldered to the metal housing (8) by a gold-tin soldering process. The inner core of the radio frequency terminal is soldered to the microstrip line (3).

6. The high-frequency electro-optic modulator with integrated microwave amplification function according to claim 1, characterized in that, The impedance matching component includes an impedance matching substrate (6) and an impedance matching circuit disposed on the surface of the impedance matching substrate (6); the impedance matching substrate (6) is made of aluminum nitride material, and the impedance matching circuit is formed on its surface by thin film etching process; one end of the impedance matching component is connected to the impedance matching port of the electro-optic modulator chip (1) by gold wire bonding, and the other end is connected to the ground terminal of the metal shell (8).

7. The high-frequency electro-optic modulator with integrated microwave amplification function according to claim 1, characterized in that, The electrical connection points of the high-frequency electro-optic modulator are connected by a gold wire bonding process.

8. The high-frequency electro-optic modulator with integrated microwave amplification function according to claim 1, characterized in that, The electro-optic modulator chip (1) is a waveguide folded thin-film lithium niobate electro-optic modulator chip, which is provided with an optical input port, an optical output port, a backlight detection grating, a microwave signal input port, an impedance matching port and a bias control port, for electro-optic modulation of optical signals in the 1530nm~1570nm band. The optical input port, optical output port and optical fiber assembly (9) are connected by optical coupling process; the backlight detection grating and the photosensitive surface of the backlight detection chip (7) are arranged opposite to each other; the microwave signal input port is electrically connected to the microstrip line (3) by gold wire bonding process; the impedance matching port is connected to the impedance matching component by gold wire bonding process, and the other end of the impedance matching component is connected to the metal housing (8); the bias control port is electrically connected to the through-hole insulated pin of the metal housing (8) by bonding gold wire.

9. The high-frequency electro-optic modulator with integrated microwave amplification function according to claim 1, characterized in that, The optical fiber assembly (9) includes an input optical fiber and an output optical fiber arranged in parallel to each other; the ends of the input optical fiber and the output optical fiber are integrated with a mode field diameter conversion structure that converts the mode field diameter from 9μm to 4μm, which is used to perform low-loss coupling with the 4μm mode field diameter waveguide end face of the electro-optic modulator chip (1).

10. The high-frequency electro-optic modulator with integrated microwave amplification function according to claim 9, characterized in that, The optical fiber assembly (9) passes through the outside of the metal housing (8) and is fitted with a metallized gold-plated nickel tube, which is welded and sealed to the metal housing (8).

Images