A continuous variable quantum key modulation system and an optical waveguide unit preparation method

Abstract

This invention provides a continuous-variable quantum key modulation system and a method for fabricating an optical waveguide unit, belonging to the field of quantum communication. It includes an integrated amplitude modulation module and a modulation control module. The integrated amplitude modulation module comprises an optical waveguide unit with an integrated Mxene film, a modulation light input unit, and a signal light coupling unit. The modulation control module receives modulation commands and transmits the corresponding modulation parameters to the integrated amplitude modulation module. The modulation light input unit receives modulation light and excites the saturable absorbance of the Mxene film according to the input light power. The signal light coupling unit receives signal light and couples the signal light and modulation light to the optical waveguide unit. The optical waveguide unit is used to perform full-amplitude modulation of the modulation light and signal light based on the modulation frequency after the saturable absorbance of the Mxene film is excited to obtain a modulated optical signal. Because the system can stably output ideal pulsed light, it avoids the information leakage problem caused by imperfect optical pulses.

Description

Technical Field

[0001] This invention belongs to the field of quantum communication, specifically relating to a continuous variable quantum key modulation system and a method for fabricating optical waveguide units. Background Technology

[0002] Quantum key distribution (QKD), based on the principles of quantum mechanics, provides a solid guarantee for the security of information transmission and theoretically possesses unconditional security. Since the concept of QKD was proposed, numerous discrete-variable QKD protocols have been put forward, driving the realization of long-distance and practical secure systems. Continuous-variable QKD, as an important branch, uses coherent states for key distribution and has significant advantages in terms of strong compatibility with the telecommunications industry. For example, it can utilize commercial lasers and zero-difference detectors, and has experienced rapid development in recent years.

[0003] Among them, local oscillator systems for continuous-variable quantum key distribution have continuously evolved into systems based on different technical solutions such as continuous-wave light and polarization multiplexing. Furthermore, the core technologies for realizing these systems, such as quantum random number generators, laser sources, quantum signal modulation, quantum signal detection, shot noise calibration, and digital signal processing and post-processing, are also continuously evolving and improving. However, existing continuous-variable quantum key distribution systems rely on modulator physical devices, and the inherent non-ideal characteristics of existing modulators allow eavesdroppers to use leaked light to conceal their attacks, resulting in poor system security. Summary of the Invention

[0004] To address the issue of poor security in existing continuous-variable quantum key distribution systems due to the non-ideal characteristics of modulators, this invention provides a continuous-variable quantum key modulation system and an optical waveguide fabrication method.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A continuous-variable quantum key modulation system includes an integrated amplitude modulation module and a modulation control module. The integrated amplitude modulation module includes an optical waveguide unit with an integrated two-dimensional transition metal carbide / nitride Mxene film, a modulation optical input unit, and a signal optical coupling unit.

[0007] The modulation control module is used to receive modulation commands and transmit the modulation parameters corresponding to the modulation commands to the integrated amplitude modulation module. The modulation commands include the input optical power and the modulation frequency.

[0008] The modulation light input unit is used to receive modulation light and excite the saturation absorption of the two-dimensional transition metal carbide / nitride Mxene film according to the input light power;

[0009] The signal-optical coupling unit is used to receive signal light and couple the signal light and modulated light to the optical waveguide unit after saturated absorption excitation;

[0010] The optical waveguide unit is used to perform full-amplitude modulation of the modulation light and the signal light based on the modulation frequency after the saturation absorption of the two-dimensional transition metal carbide / nitride Mxene film is excited, so as to obtain the modulated optical signal.

[0011] Optionally, the continuous variable quantum key modulation system provided by the present invention further includes an integrated optical power limiting module;

[0012] The integrated optical power limiting module is used to receive signal light and calculate the optical signal power. When the modulated optical signal power is greater than the preset first safety threshold, the light intensity of the signal light is limited so that the integrated amplitude modulation module can modulate the optical amplitude.

[0013] Optionally, the continuous variable quantum key modulation system provided by the present invention integrates an optical power limiting module including an optical power detection unit, a power limiting execution unit, and a feedback adjustment unit;

[0014] The optical power detection unit is used to receive signal light and detect the optical signal power.

[0015] The power limiting execution unit is used to limit the light intensity of the signal light when the signal light power is greater than the first safety threshold.

[0016] The feedback adjustment unit is used to feed back to the power limiting execution unit when the signal light power after light intensity limitation is greater than the second safety threshold, so that the power limiting execution unit can adjust the light signal after light intensity limitation. The second safety threshold is less than the first safety threshold.

[0017] Optionally, the continuous-variable quantum key modulation system provided by the present invention further includes a signal preprocessing module:

[0018] The signal preprocessing module is used to receive the signal light, denoise the signal light, and transmit it to the integrated amplitude modulation module and the integrated optical power limiting module respectively.

[0019] Optionally, the continuous variable quantum key modulation system provided by the present invention includes a signal preprocessing module comprising a filtering submodule and an amplification submodule;

[0020] The filtering submodule is used to filter the signal light to obtain the filtered signal light;

[0021] The amplification submodule is used to amplify the filtered signal light to obtain the denoised signal light.

[0022] Optionally, the continuous variable quantum key modulation system provided by the present invention further includes a power monitoring and feedback module;

[0023] The power monitoring and feedback module is used to measure the power of the signal light after intensity limiting in real time and feed it back to the integrated optical power limiting module, so that the integrated optical power limiting module can limit the intensity of the signal light.

[0024] Optionally, the continuous variable quantum key modulation system provided by the present invention includes an optical power measurement submodule and a data transmission submodule in its power monitoring and feedback module;

[0025] The optical power measurement submodule is used to measure the power of the signal light after intensity limiting in real time;

[0026] The data transmission submodule is used to feed back the power information of the intensity-limited signal light to the integrated optical power limiting module.

[0027] Optionally, the continuous variable quantum key modulation system provided by the present invention includes a modulation control module comprising a parameter setting submodule and a real-time adjustment submodule;

[0028] The parameter setting submodule is used to receive modulation commands, generate modulation parameters, and transmit them to the integrated amplitude modulation module;

[0029] The real-time adjustment submodule uses the power of the signal light after obtaining the light intensity limit and adjusts the modulation parameters to generate the adjusted modulation parameters and transmit them to the integrated amplitude modulation module for all-optical amplitude modulation.

[0030] Optionally, the continuous variable quantum key modulation system provided by the present invention further includes a security assessment module;

[0031] The safety assessment module is used to collect the operating data of the integrated amplitude modulation module and modulation control module in real time, and to analyze and evaluate them in combination with the preset safety algorithm.

[0032] This invention also provides a method for fabricating an optical waveguide unit, wherein the optical waveguide unit integrates a two-dimensional transition metal carbide / nitride Mxene film, and is applied to any of the above-mentioned continuous-variable quantum key modulation systems. The method includes:

[0033] A solution containing two-dimensional MXene nanosheets was obtained by etching the MAX phase material with LiF / HCl solution.

[0034] A silica substrate was immersed in an MXene solution for electrostatic adsorption self-assembly to obtain a multilayer MXene film, wherein the silica substrate carries an opposite charge to the MXene solution.

[0035] Photolithography and dry etching are performed on the silicon dioxide layer of the silicon nitride waveguide to obtain a silicon nitride waveguide with a windowed region. The silicon nitride waveguide is pre-deposited with silicon dioxide to form a silicon dioxide layer.

[0036] Multilayer Mxene films were coated layer by layer onto the windowed region of the silicon nitride waveguide to obtain an optical waveguide unit with integrated two-dimensional transition metal carbide / nitride Mxene films.

[0037] The continuous-variable quantum key modulation system provided by this invention has the following advantages:

[0038] Because the modulation module in the continuous-variable quantum key distribution system provided by this invention includes an optical waveguide unit integrating a two-dimensional transition metal carbide / nitride Mxene film, it can achieve all-optical modulation by utilizing the saturated absorption characteristics of Mxene material. The response time is limited only by the carrier relaxation time, reaching terahertz-level modulation speeds. This allows the modulator to stably output ideal pulsed light under high-speed modulation conditions, effectively avoiding information leakage problems caused by imperfect optical pulses and greatly improving the security of the continuous-variable quantum key distribution system. Furthermore, the change in the refractive index of the Mxene film caused by the switching light is small and does not significantly alter the waveguide mode of the micro-fiber, facilitating integration into standard fiber optic systems and enabling efficient intra-fiber operation, thereby improving the system's integration and practicality.

[0039] Specifically, the optical waveguide unit in the continuous variable quantum key modulation system provided by this invention is prepared by coating multiple Mxene films on a silicon nitride waveguide. This integrates the key functions of the continuous variable quantum key modulation system into a specific device, further enhancing the security and stability of the continuous variable quantum key modulation system, and thus ensuring the security of continuous variable quantum distribution. Attached Figure Description

[0040] To more clearly illustrate the embodiments and design schemes of the present invention, the accompanying drawings required for this embodiment will be briefly described below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a schematic diagram of the optical waveguide unit fabrication method provided in an embodiment of the present invention;

[0042] Figure 2 This invention provides an example of a continuous variable quantum key modulation system framework. Detailed Implementation

[0043] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0044] Quantum key distribution system architectures include two types: in-path local oscillators (LANs) and local oscillators. The development of in-path LAN systems has progressed through stages including early system construction, breakthroughs in long-distance transmission, field testing and applications, and exploration of chip-based systems. Similarly, local oscillator systems have also evolved from early systems, developing into systems based on different technologies such as continuous wave light and polarization multiplexing, achieving a series of recent advancements. The core technologies required to realize these systems, including quantum random number generators, laser sources, quantum signal modulation, quantum signal detection, shot noise calibration, and digital signal processing and post-processing, are also continuously evolving and improving.

[0045] However, continuous-variable quantum key distribution systems still face significant challenges in practical applications. The non-ideal characteristics of the physical components on which the system relies, such as light sources, modulators, and detectors, pose a major threat to system security. For example, amplitude modulators (AM) under high-speed modulation produce imperfect light pulses. When the modulation frequency exceeds a certain threshold, such as 500MHz, the output pulse is not an ideal single smooth peak pulse, but rather two adjacent pulses. This imperfection of the light pulse allows eavesdroppers to use leaked light to alter the parameter estimation results of the communicating parties, such as affecting the intensity of the local oscillator light, causing the noise to be underestimated, thereby masking their attack behavior and seriously threatening the security of the system.

[0046] Furthermore, attacks based on high-power laser injection also pose a significant challenge to system security. Such attacks interfere with the signal characteristics at the transmitter, allowing attackers to partially control the signal modulation process. In measurement-device-independent quantum key distribution (CV-MDI-QKD) systems, laser seeding and laser damage attacks can cause Gaussian-modulated coherent states to deviate from their ideal state, reducing system security.

[0047] Furthermore, various types of noise exist in practical systems, such as light source noise, electrical noise, phase noise, and shot noise. These noises interfere with the preparation, transmission, and measurement of quantum signals, severely affecting the accurate assessment of the secure key rate and further increasing the difficulty of secure system applications. Current solutions to these problems are incomplete and fail to meet the stringent security and reliability requirements of continuous-variable quantum key distribution systems in real-world scenarios.

[0048] The continuous variable quantum key modulation system provided by this invention has developed an integrated device that can solve the problems of security risks caused by device imperfections and noise affecting the evaluation of secure key rates in existing CV-QKD systems. When applied to continuous variable quantum key distribution systems, it ensures the security of the system and is of great significance for promoting the widespread application of continuous variable quantum key distribution systems in practice.

[0049] Example 1

[0050] This invention provides a continuous variable quantum key modulation system, including an integrated amplitude modulation module and a modulation control module. The integrated amplitude modulation module includes an optical waveguide unit with an integrated two-dimensional transition metal carbide / nitride Mxene film, a modulation optical input unit, and a signal optical coupling unit.

[0051] The modulation control module is used to receive modulation commands and transmit the modulation parameters corresponding to the modulation commands to the integrated amplitude modulation module. The modulation commands include the input optical power and the modulation frequency.

[0052] The modulation light input unit is used to receive modulation light and excite the saturation absorption of the two-dimensional transition metal carbide / nitride Mxene film according to the input light power.

[0053] The signal-optical coupling unit is used to receive the signal light and couple the signal light and the modulated light to the optical waveguide unit after saturated absorption excitation.

[0054] The optical waveguide unit is used to perform full-amplitude modulation of the modulation light and the signal light based on the modulation frequency after the saturation absorption of the two-dimensional transition metal carbide / nitride Mxene film is excited, so as to obtain the modulated optical signal.

[0055] Specifically, the continuous-variable quantum key distribution system provided by this invention includes an MXene-based ultrafast integrated amplitude modulation module and a modulation control module. The MXene-based ultrafast integrated amplitude modulation module is used to modulate the amplitude of the optical signal in the continuous-variable quantum key distribution system, solving the problem of imperfect optical pulses under high-speed modulation and preventing information leakage. For example, the MXene-based ultrafast integrated amplitude modulation module and modulation control module receive the optical signal from the light source, utilize the saturable absorption characteristics of MXene material to achieve all-optical modulation, ensuring stable output of ideal pulsed light in the high-frequency system, and outputting the modulated optical signal, such as pulsed light, to other system modules to achieve quantum key distribution.

[0056] The ultrafast integrated amplitude modulation module based on MXene includes an optical waveguide unit integrating a two-dimensional transition metal carbide / nitride Mxene film, a modulation light input unit, and a signal light coupling unit. The modulation light input unit receives modulation light from a fiber pulsed laser and uses a variable optical attenuator to adjust the input light power, stimulating the saturable absorption characteristics of the MXene material. The signal light coupling unit combines the signal light from the signal source with the modulation light via wavelength division multiplexing using a beam combiner, and then couples them into the optical waveguide integrating the MXene film to achieve signal modulation. The optical waveguide unit integrating the two-dimensional transition metal carbide / nitride Mxene film enables both optical signal transmission and modulation.

[0057] The modulation control module controls the modulation parameters of the MXene-based ultrafast integrated amplitude modulation module to ensure that the modulation effect meets system requirements. For example, the modulation control module receives control commands and feedback information from the system, and adjusts parameters such as the input optical power and modulation frequency of the MXene-based ultrafast integrated amplitude modulation module according to the commands and information, thereby achieving precise modulation of the optical signal amplitude.

[0058] Because the modulation module in the continuous-variable quantum key distribution system provided by this invention includes an optical waveguide unit integrating a two-dimensional transition metal carbide / nitride Mxene film, it can achieve all-optical modulation by utilizing the saturated absorption characteristics of Mxene material. The response time is limited only by the carrier relaxation time, reaching terahertz-level modulation speed. This allows the modulator to stably output ideal pulsed light under high-speed modulation conditions, effectively avoiding information leakage caused by imperfect optical pulses and greatly improving the security of the continuous-variable quantum key distribution system. Furthermore, the modulator is extremely small, only 0.5 mm × 10 μm, and the change in refractive index of the Mxene film caused by switching light is small, not significantly altering the waveguide mode of the micro-fiber. This facilitates integration into standard fiber optic systems, enabling efficient intra-fiber operation, thereby improving the system's integration and practicality.

[0059] Based on the above embodiments, the continuous variable quantum key modulation system provided by the present invention further includes an integrated optical power limiting module.

[0060] The integrated optical power limiting module is used to receive signal light and calculate the optical signal power. When the modulated optical signal power is greater than the preset first safety threshold, the light intensity of the signal light is limited so that the integrated amplitude modulation module can modulate the optical amplitude.

[0061] Specifically, the continuous variable quantum key modulation system provided by this invention also includes an integrated optical power limiting module for resisting laser seeding attacks and laser damage attacks, ensuring the stability of the Gaussian modulated coherent state in the system. The integrated optical power limiting module receives the optical signal transmitted from the quantum light source through the quantum channel, monitors the optical signal power in real time, and when the optical signal power exceeds a first security threshold, limits the light intensity to the microwatt level. The processed optical signal is then output to the system's detection module for monitoring and feedback adjustment by the power monitoring and feedback module.

[0062] Because the continuous-variable quantum key modulation system provided by this invention incorporates an integrated optical power limiting module to protect system security, it can effectively resist laser seeding attacks and laser damage attacks, stably limiting the intensity of the injected attack light to the microwatt level. This ensures the stability of the Gaussian modulated coherent state in the system, providing reliable security protection for the continuous-variable quantum key distribution system when facing potential laser attack threats, thus enhancing the system's security and reliability. In practical applications, it ensures that the system can still operate normally and securely in complex optical environments, effectively improving the system's anti-interference capability.

[0063] Based on the above embodiments, the continuous variable quantum key modulation system provided by the present invention integrates an optical power limiting module including an optical power detection unit, a power limiting execution unit, and a feedback adjustment unit.

[0064] The optical power detection unit is used to receive signal light and perform optical signal power detection.

[0065] The power limiting execution unit is used to limit the light intensity of the signal light when the signal light power is greater than the first safety threshold.

[0066] The feedback adjustment unit is used to feed back to the power limiting execution unit when the signal light power after light intensity limitation is greater than the second safety threshold, so that the power limiting execution unit can adjust the light signal after light intensity limitation. The second safety threshold is less than the first safety threshold.

[0067] Specifically, the continuous variable quantum key modulation system provided by this invention integrates an optical power limiting module, including an optical power detection unit for real-time detection of the power of the input optical signal and determination of the presence of attack light; a power limiting execution unit for limiting the light intensity when the optical power detection unit detects that the optical power exceeds a first security threshold; and a feedback adjustment unit for dynamically adjusting the operating parameters of the power limiting execution unit based on feedback information of the output optical power. The optical power detection unit receives the optical signal transmitted by the quantum light source through the quantum channel using a detection device such as an optical power meter, and measures the optical power in real time, combining this measurement with a pre-set first security threshold to determine whether attack light is present. The power limiting execution unit receives the detection result from the optical power detection unit. When the optical power detection unit detects that the modulated optical signal is greater than the first security threshold, the power limiting execution unit initiates a corresponding power limiting mechanism to limit the light intensity within a safe range. Furthermore, since the modulated optical signal output by the integrated amplitude modulation module is monitored by the power monitoring and feedback module, if the power of the optical signal is still too high after the power limiting execution unit activates the corresponding power limiting mechanism, for example, if it is close to the upper limit of the first safety threshold or exceeds the second safety threshold, the power monitoring and feedback module generates feedback information and transmits it to the feedback adjustment unit. The feedback adjustment unit then dynamically fine-tunes the operating parameters of the power limiting execution unit to ensure that the output optical signal is stably within the range corresponding to the first safety threshold.

[0068] Because the continuous variable quantum key modulation system provided by this invention uses the optical power detection unit, power limiting execution unit and feedback adjustment unit to work together to dynamically adjust and control the light intensity of the optical signal, it ensures that the power of the optical signal is always within the range corresponding to the safety threshold, avoids the impact of excessive optical power on the system, and further ensures the anti-interference capability of the system.

[0069] Based on the above embodiments, the continuous variable quantum key modulation system provided by the present invention further includes a signal preprocessing module:

[0070] The signal preprocessing module is used to receive the signal light, denoise the signal light, and transmit it to the integrated amplitude modulation module and the integrated optical power limiting module respectively.

[0071] Specifically, the continuous variable quantum key modulation system provided by this invention also includes a signal preprocessing module that performs preliminary processing on the raw optical signal entering the system to improve signal quality, thereby providing a higher quality signal for subsequent modulation and detection. The signal preprocessing module receives the raw optical signal from the quantum light source, i.e., the signal light that has not yet been input into the MXene-based ultrafast integrated amplitude modulation module for signal-optical coupling. It removes noise interference from the raw optical signal through filtering, amplification, and other operations, and then inputs the denoised signal light into the MXene-based ultrafast integrated amplitude modulation module for modulation, and finally inputs it into the integrated optical power limiting module for attack light determination.

[0072] Because the signal preprocessing module provided by this invention performs preprocessing operations such as filtering and amplification on the original optical signal, it provides a high-quality signal for subsequent modulation and detection, improves the system's signal processing accuracy and efficiency, and ensures the stability of the modulation system.

[0073] Based on the above embodiments, the continuous variable quantum key modulation system provided by the present invention includes a signal preprocessing module comprising a filtering submodule and an amplification submodule.

[0074] The filtering submodule is used to filter the signal light to obtain the filtered signal light.

[0075] The amplification submodule is used to amplify the filtered signal light to obtain the denoised signal light.

[0076] Specifically, in the continuous-variable quantum key modulation system provided by this invention, the signal preprocessing module includes a filtering submodule for removing noise and interference signals from the original optical signal and an amplification submodule for amplifying the filtered optical signal to improve signal strength. The filtering submodule uses bandpass filters and other filtering devices to filter the original optical signal, allowing only optical signals within a specific frequency range to pass through, thereby obtaining the filtered signal light. The amplification submodule uses optical amplifiers and other devices to amplify the filtered signal light, ensuring that the amplified signal light meets the signal strength requirements of subsequent MXene-based ultrafast integrated amplitude modulation modules, integrated optical power limiting modules, and other modules.

[0077] Because the continuous variable quantum key modulation system provided by this invention uses a filtering submodule and an amplification submodule in combination, it can amplify the signal strength while filtering out noise, thus avoiding the interference of light source noise on transmission and measurement processes, and further ensuring the system's anti-interference capability and stability.

[0078] Based on the above embodiments, the continuous variable quantum key modulation system provided by the present invention also includes a power monitoring and feedback module.

[0079] The power monitoring and feedback module is used to measure the power of the signal light after intensity limiting in real time and feed it back to the integrated optical power limiting module, so that the integrated optical power limiting module can limit the intensity of the signal light.

[0080] Specifically, the continuous-variable quantum key modulation system provided by this invention also includes a power monitoring and feedback module capable of real-time monitoring of the output optical power of the integrated optical power limiting module and feeding back the monitoring results to the modulation control module and the system control center. The power monitoring and feedback module receives the output optical signal from the integrated optical power limiting module in real time and measures the optical power. It then transmits the power data corresponding to the optical power level to relevant modules such as the feedback adjustment unit, allowing the integrated optical power limiting module to adjust its parameters based on the power situation, ensuring that the optical signal power remains stable within a safe threshold range. In the continuous-variable quantum key modulation system provided by this invention, the optical power detection unit within the integrated optical power limiting module is primarily used for real-time detection within the integrated optical power limiting module, while the optical power measurement submodule within the power monitoring and feedback module is used for secondary monitoring and detection of the output power in an external system.

[0081] Because the continuous variable quantum key modulation system provided by this invention is equipped with a power monitoring and feedback module, it can monitor the output optical power of the integrated optical power limiting module in real time and feed the results back to the relevant modules, providing accurate data for system adjustment and realizing dynamic optimization and stable operation of the system.

[0082] Based on the above embodiments, the continuous variable quantum key modulation system provided by the present invention includes an optical power measurement submodule and a data transmission submodule in its power monitoring and feedback module.

[0083] The optical power measurement submodule is used to measure the power of the signal light after intensity limiting in real time.

[0084] The data transmission submodule is used to feed back the power information of the intensity-limited signal light to the integrated optical power limiting module.

[0085] Specifically, the power monitoring and feedback module in the continuous-variable quantum key modulation system provided by this invention includes an optical power measurement submodule for accurately measuring the output optical power of the integrated optical power limiting module and a data transmission submodule for transmitting the measured optical power data to the modulation control module and the system control center. The optical power measurement submodule measures the power of the output optical signal using a high-precision optical power meter or similar equipment. Subsequently, the data transmission submodule transmits the measured power data to relevant modules via a communication interface, facilitating parameter adjustment and security assessment of the integrated optical power limiting module within the system.

[0086] Because the power monitoring and feedback module provided by this invention can achieve accurate power measurement and data feedback, it ensures that the integrated optical power limiting module can stably limit the power of the signal light within a safe threshold range, thereby achieving the effect of resisting laser seeding attacks and laser damage attacks, and enhancing the security and reliability of the system.

[0087] Based on the above embodiments, the continuous variable quantum key modulation system provided by the present invention includes a modulation control module comprising a parameter setting submodule and a real-time adjustment submodule.

[0088] The parameter setting submodule is used to receive modulation commands, generate modulation parameters, and transmit them to the integrated amplitude modulation module.

[0089] The real-time adjustment submodule uses the power of the signal light after obtaining the light intensity limit and adjusts the modulation parameters to generate the adjusted modulation parameters and transmit them to the integrated amplitude modulation module for all-optical amplitude modulation.

[0090] Specifically, in the continuous-variable quantum key distribution modulation system provided by this invention, the modulation control module includes a parameter setting submodule for setting the modulation parameters of the MXene-based ultrafast integrated amplitude modulation module according to system requirements and actual conditions, and a real-time adjustment submodule for adjusting the modulation parameters of the modulation module in real time based on feedback information from the power monitoring and feedback module. The parameter setting submodule receives control commands from the system and generates parameters such as input optical power and modulation frequency for the MXene-based ultrafast integrated amplitude modulation module to perform all-optical modulation. The real-time adjustment submodule receives power data from the power monitoring and feedback module and dynamically adjusts the modulation parameters in real time according to data changes, ensuring the stability of the modulation effect of the MXene-based ultrafast integrated amplitude modulation module when power data fluctuates.

[0091] In the continuous variable quantum key modulation system provided by this invention, the modulation control module can determine the modulation parameters based on the system's control commands and dynamically adjust the modulation parameters based on the feedback data from the power monitoring and feedback module. This allows for precise control of the modulation parameters of the MXene-based ultrafast integrated amplitude modulator, ensuring stable and reliable modulation effects, further optimizing the modulation process, and improving system performance.

[0092] Based on the above embodiments, the continuous variable quantum key modulation system provided by the present invention also includes a security assessment module.

[0093] The safety assessment module is used to collect the operating data of the integrated amplitude modulation module and modulation control module in real time, and to analyze and evaluate them in combination with the preset safety algorithm.

[0094] Specifically, the continuous-variable quantum key modulation system provided by this invention also includes a security assessment module that performs real-time security evaluation to detect potential security threats. The security assessment module receives operational data and signal information from modules such as the MXene-based ultrafast integrated amplitude modulation module, integrated optical power limiting module, signal preprocessing module, modulation control module, and power monitoring and feedback module. It then analyzes and evaluates the system's security using preset security algorithms and models. Furthermore, when the security assessment module detects a security vulnerability, it can promptly generate alarm information and send an alert to the system's control center.

[0095] The security assessment module includes a data collection submodule for gathering operational data and signal information from various modules; a security analysis submodule for analyzing the collected data and assessing system security; and an alarm sending submodule for sending alerts to the system control center when security risks are detected. Specifically, the data collection submodule connects to each module via a data interface to collect system operational data and signal information in real time. The security analysis submodule uses preset security algorithms and models to analyze and process the data to determine if a security threat exists. When the security analysis submodule determines that a security threat exists, the alarm sending submodule sends an alarm message to the system control center via a communication interface.

[0096] Because the security assessment module provided by this invention analyzes data from each module in real time, it promptly detects potential security threats and issues alerts, thus comprehensively ensuring the system's security. Furthermore, the security assessment module works in conjunction with the other modules mentioned above to improve the overall performance and security of the continuous-variable quantum key distribution system from multiple dimensions, ensuring that the system can operate stably, efficiently, and securely in complex environments.

[0097] Example 2

[0098] This invention also provides a method for fabricating an optical waveguide unit, wherein the optical waveguide unit integrates a two-dimensional transition metal carbide / nitride Mxene film, and is applied to any of the above-mentioned continuous-variable quantum key modulation systems. The method includes:

[0099] Step 11: Etch the MAX phase material with LiF / HCl solution to obtain an MXene solution containing two-dimensional MXene nanosheets.

[0100] Step 12: Immerse the silica substrate in the MXene solution for electrostatic adsorption self-assembly to obtain a multilayer MXene film, wherein the silica substrate carries an opposite charge to the MXene solution.

[0101] Step 13: Perform photolithography and dry etching on the silicon dioxide layer of the silicon nitride waveguide to obtain a silicon nitride waveguide with a windowed region. The silicon nitride waveguide is pre-deposited with silicon dioxide to form a silicon dioxide layer.

[0102] Step 14: Coat the multilayer Mxene film layer by layer on the windowed area of ​​the silicon nitride waveguide to obtain an optical waveguide unit with integrated two-dimensional transition metal carbide / nitride Mxene film.

[0103] Specifically, multilayer MXene films can be prepared in the following manner:

[0104] First, negatively charged two-dimensional MXene nanosheets were synthesized by etching the MAX phase material with LiF and HCl solutions, thus preparing a negatively charged MXene solution. Next, a positively charged polyelectrolyte polydimethylammonium chloride (PDDA) polymer solution was prepared. A silica substrate with a negatively charged surface was immersed in the PDDA polymer solution. According to the principle of electrostatic adsorption, the substrate surface will acquire a positive charge due to the electrostatic interaction. Specifically, the Coulomb force is shown in formula (1):

[0105] (1)

[0106] in, Let be the Coulomb constant, and r be the distance between charges. This represents the original charge on the substrate surface. The amount of opposite charge carried by the PDDA polymer solution. The electrostatic attraction is Coulomb force. Under this electrostatic attraction, the PDDA polymer adsorbs onto the substrate surface. Subsequently, the polymer-coated substrate is rinsed with deionized distilled water to remove any loosely adsorbed polymer, and then dried with nitrogen.

[0107] Finally, the polymer-coated substrate is immersed in the prepared MXene solution. Under the action of charge, MXene nanosheets self-assemble on the substrate surface to form a monolayer of MXene. The monolayer MXene film is repeatedly deposited to obtain a multilayer MXene film.

[0108] Once the multilayer MXene thin film is fabricated, the integrated optical waveguide unit can be prepared using the following method:

[0109] First, a silicon nitride waveguide is fabricated using a crack-free process compatible with complementary metal-oxide-semiconductor (CMOS), and a silicon dioxide layer of approximately 2.3 μm thickness is deposited on the silicon nitride waveguide as the upper cladding.

[0110] Subsequently, windows are created on the silicon dioxide layer using photolithography and dry etching processes. The photolithography process is based on a photochemical reaction, utilizing the cross-linking or decomposition of the photoresist under light to transfer the pattern from the mask onto the photoresist. The light absorption law is shown in formula (2):

[0111] (2)

[0112] Where I represents light intensity. denoted as the absorption coefficient of the photoresist for a specific wavelength of light, and x as the propagation distance of the light in the photoresist. By controlling the incident light intensity, the reaction area of ​​the photoresist can be precisely controlled by adjusting the exposure time and light intensity. Dry etching, on the other hand, uses ions and free radicals in plasma to etch silicon dioxide. By controlling parameters such as the type, flow rate, and power of the etching gas, precise control over the window size and shape can be achieved.

[0113] After windows are created on the silicon dioxide layer using the aforementioned photolithography and dry etching processes, the prepared multilayer MXene thin film is coated onto the windowed area of ​​the waveguide without transfer, layer by layer, using a solution-based coating method.

[0114] In summary, the optical waveguide unit in the continuous-variable quantum key modulation system provided by this invention is fabricated by coating multiple Mxene films onto a silicon nitride waveguide. This integrates the key functions of the continuous-variable quantum key modulation system into a specific device, further enhancing the security and stability of the continuous-variable quantum key modulation system, and thus ensuring the security of continuous-variable quantum distribution.

[0115] Example 3

[0116] Based on Examples 1 and 2, such as Figure 2As shown, this invention also provides a specific example of a continuous-variable quantum key distribution (QHD) system, including an MXene-based ultrafast integrated amplitude modulation module, an integrated optical power limiting module, a signal preprocessing module, a modulation control module, a power monitoring and feedback module, and a security assessment module. First, the original signal light is input to the signal preprocessing module for filtering, amplification, and other preprocessing operations. Then, the processed signal light is input into the MXene-based ultrafast integrated amplitude modulation module to participate in the generation of modulated light, and simultaneously input into the integrated optical power limiting module for power monitoring and intensity limiting. The power monitoring and feedback module externally monitors the optical power. Based on the monitoring results, the security assessment module performs a system security assessment, and the modulation control module adjusts the modulation parameters of the MXene-based ultrafast integrated amplitude modulation module. Finally, according to the modulation parameters, the MXene-based ultrafast integrated amplitude modulation module performs wavelength division multiplexing (WDM) on the preprocessed signal light and the modulated light via a beam combiner before inputting them into the optical waveguide to achieve signal light modulation.

[0117] The MXene-based ultrafast integrated amplitude modulation module includes a modulation light input unit, a signal light coupling unit, and an optical waveguide unit with integrated multilayer MXene thin films prepared by the method in Example 2. Specifically, the modulation light input unit is mainly used to receive modulation light with a center wavelength of approximately 1560 nm emitted from a fiber pulsed laser, and adjusts the power of the input light through a variable optical attenuator (VOA), as shown in formula (3):

[0118] (3)

[0119] in, This is the attenuation coefficient of VOA for light. For input optical power, To control the output optical power, the attenuation coefficient of the VOA is controlled by utilizing the absorption and reflection characteristics of light to achieve precise adjustment of the input optical power.

[0120] The signal-optical coupling unit performs wavelength division multiplexing (WDM) on the signal light (approximately 1550 nm wavelength) and the modulation light from the signal source via a beam combiner. Utilizing the independent propagation characteristics of different wavelengths of light in optical fiber, let the wavelength of the signal light be... The wavelength of the modulated light is By using specific wavelength division multiplexing (WDM) devices, light of two different wavelengths can be transmitted in the same optical fiber without interfering with each other. Then, the multiplexed light input is integrated into a multilayer MXene thin-film optical waveguide unit to modulate the signal light.

[0121] The integrated optical power limiting module includes an optical power detection unit, a power limiting execution unit, and a feedback adjustment unit. Specifically, the optical power detection unit receives the optical signal from the quantum channel through an optical power meter and detects the power of the input optical signal in real time. The optical power meter operates based on the photoelectric effect; when light shines on the photodetector, the resulting photocurrent is shown in formula (4):

[0122] (4)

[0123] in, The loudness of the photodetector. For optical power, The photocurrent is the optical current. Since the magnitude of the photocurrent is directly proportional to the optical power, the optical power can be calculated by measuring the magnitude of the photocurrent using an optical power meter.

[0124] Once the optical power is detected, the optical power detection unit will convert the optical power... With a pre-set security threshold Comparison, when optical power Greater than the safety threshold When the light intensity is limited, the power limiting execution unit activates the corresponding power limiting mechanism based on principles such as optical absorption, optical reflection, or optical scattering to limit the light intensity within a safe range.

[0125] Furthermore, the feedback adjustment unit in the integrated optical power limiting module receives feedback information generated by the power detection and feedback module based on real-time data of the output optical power of the integrated optical power limiting module, and fine-tunes the parameters of the power limiting execution unit in conjunction with a safety threshold. For example, when the power detection and feedback module measures the real-time power data of the output light from the integrated optical power limiting module and feeds it back to the feedback adjustment unit, if the feedback adjustment unit detects that the real-time power data is close to the upper limit of the safety threshold, it can adjust the operating parameters of the power limiting execution unit, enhancing the power limiting execution unit's ability to limit optical power, thereby ensuring that the output optical power remains stable within the safety threshold range.

[0126] The signal preprocessing module includes a filtering submodule and an amplification submodule. Specifically, the filtering submodule is equipped with a bandpass filter, which filters the original optical signal based on its selective transmission characteristics for optical signals within a specific frequency range. The frequencies of the original optical signal that can pass through the filter are shown in formula (5):

[0127] (5)

[0128] in, The center frequency of the bandpass filter. For bandwidth, The frequencies of the original optical signal that can pass through the filter are excluded; other frequencies are suppressed and cannot pass through. The amplification submodule is equipped with an optical amplifier, which amplifies the filtered optical signal based on stimulated emission. The power of the amplified optical signal is shown in formula (6).

[0129] (6)

[0130] in, For the gain of the optical amplifier, The optical signal power input to the optical amplifier. This refers to the power of the optical signal output from the optical amplifier. It should be emphasized that the optical amplifier and its operating parameters in the amplification submodule only need to ensure that the filtered optical signal reaches the signal strength required by subsequent modules; this invention does not impose any limitations.

[0131] The modulation control module includes a parameter setting submodule and a real-time adjustment submodule. The parameter setting submodule receives control commands from the system and sets the modulation parameters of the MXene-based ultrafast integrated amplitude modulation module according to system requirements and actual conditions. For example, it determines parameters such as modulation frequency and input optical power based on communication rate and channel characteristics. The real-time adjustment submodule receives power data from the power monitoring and feedback module and, when a change in optical power is detected, adjusts the modulation parameters of the MXene-based ultrafast integrated amplitude modulation module in real time according to the change. For example, it adjusts the power change parameters accordingly. That is, when the optical power increases, in order to ensure the stability of the modulation effect, the modulation frequency can be appropriately reduced or the input optical power can be reduced. The specific adjustment amount shall be determined by those skilled in the art based on actual needs and experimental data or theoretical models from a limited number of experiments. This invention does not impose any restrictions.

[0132] The power monitoring and feedback module includes an optical power measurement submodule and a data transmission submodule. Specifically, the optical power measurement submodule uses a high-precision optical power meter to accurately measure the output optical power of the integrated optical power limiting module. To ensure accurate optical power data acquisition, a measurement accuracy of up to [insert accuracy here] is selected. Optical power meter For measurement accuracy, the data transmission submodule transmits the measured optical power data to the modulation control module and the system control center via a communication interface. This communication interface can utilize fiber optic or wireless communication to ensure timely and accurate transmission of optical power data to relevant modules for system adjustments and safety assessments.

[0133] The security assessment module includes a data collection submodule, a security analysis submodule, and an alarm sending submodule. The data collection submodule connects to each module via a data interface using a standardized data transmission protocol, collecting operational data and signal information from each module in real time while ensuring the accuracy and stability of data transmission. The security analysis submodule uses preset security algorithms and models to analyze the collected data and determine whether the system faces any security threats. For example, it analyzes the covariance matrix of phase noise as shown in formula (7):

[0134] (7)

[0135] in, The system calculates relevant parameters based on formulas to assess its security. For example, if the security index calculated from the phase noise covariance matrix exceeds a preset range, a security threat is identified. The alarm sending submodule then sends an alarm message containing information such as the type of security threat and its potential impact range to the system control center via a communication interface, enabling the system control center to take timely measures to address the security threat.

[0136] In summary, the continuous-variable quantum key distribution modulation system provided by this invention includes an ultrafast integrated amplitude modulator based on MXene and an integrated optical power limiter. The ultrafast integrated amplitude modulator based on MXene utilizes the saturable absorption characteristics of MXene to achieve all-optical modulation. Its response time is limited only by the carrier relaxation time, reaching terahertz-level modulation speeds. Under high-speed modulation, it can stably output ideal pulsed light, avoiding information leakage. The integrated optical power limiter effectively resists laser seeding attacks and laser damage attacks, limiting the intensity of the attack light to the microwatt level, ensuring system security.

[0137] Thanks to an innovative device design architecture that integrates critical system functions into specific devices, the system's security and stability are enhanced, enabling it to effectively address security threats in real-world applications. Furthermore, by optimizing device performance, such as the modulation depth and speed of the modulator and the optical intensity limiting capability of the limiter, efficient utilization of system resources is achieved, improving communication quality and key generation efficiency. Through the collaborative work of these two integrated devices, signal quality is ensured when the amplitude modulator faces high-speed modulation challenges, while the optical power limiter safeguards the system in the event of an attack, thus enhancing the overall security and reliability of the system.

[0138] Those skilled in the art will understand that embodiments of the present invention can provide methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0139] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, as well as combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0140] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0141] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0142] It should be noted that the above specific embodiments enable those skilled in the art to more fully understand the present invention, but do not limit the present invention in any way. Therefore, although the present invention has been described in detail in this specification and embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention; and all technical solutions and improvements that do not depart from the spirit and scope of the present invention are covered within the protection scope of the present invention patent. No reference numerals in the claims should be construed as limiting the scope of the claims. Any simple variations or equivalent substitutions of technical solutions that can be readily obtained by those skilled in the art within the scope of the technology disclosed in the present invention are within the protection scope of the present invention.

Claims

1. A continuous-variable quantum key modulation system, characterized in that, It includes an integrated amplitude modulation module and a modulation control module. The integrated amplitude modulation module includes an optical waveguide unit with an integrated two-dimensional transition metal carbide / nitride Mxene film, a modulation optical input unit, and a signal optical coupling unit. The modulation control module is used to receive modulation commands and transmit modulation parameters corresponding to the modulation commands to the integrated amplitude modulation module, wherein the modulation commands include input optical power and modulation frequency; The modulation light input unit is used to receive modulation light and excite the saturation absorption of the two-dimensional transition metal carbide / nitride Mxene film according to the input light power. The signal-optical coupling unit is used to receive signal light and couple the signal light and the modulated light to the optical waveguide unit after saturated absorption excitation; The optical waveguide unit is used to perform full-amplitude modulation of the modulation light and the signal light based on the modulation frequency after the saturation absorption of the two-dimensional transition metal carbide / nitride Mxene film is excited, so as to obtain the modulated optical signal.

2. The continuous-variable quantum key modulation system according to claim 1, characterized in that, The system also includes an integrated optical power limiting module; The integrated optical power limiting module is used to receive the signal light and calculate the optical signal power. When the modulated optical signal power is greater than a preset first safety threshold, the light intensity of the signal light is limited so that the integrated amplitude modulation module can modulate the optical amplitude.

3. A continuous-variable quantum key modulation system according to claim 2, characterized in that, The integrated optical power limiting module includes an optical power detection unit, a power limiting execution unit, and a feedback adjustment unit; The optical power detection unit is used to receive the signal light and perform optical signal power detection; The power limiting execution unit is used to limit the light intensity of the signal light when the signal light power is greater than the first safety threshold. The feedback adjustment unit is used to feed back to the power limiting execution unit when the signal light power after the light intensity limitation is greater than the second safety threshold, so that the power limiting execution unit can adjust the light signal after the light intensity limitation, wherein the second safety threshold is less than the first safety threshold.

4. A continuous-variable quantum key modulation system according to claim 2, characterized in that, The system also includes a signal preprocessing module: The signal preprocessing module is used to receive the signal light, denoise the signal light, and transmit it to the integrated amplitude modulation module and the integrated optical power limiting module respectively.

5. A continuous-variable quantum key modulation system according to claim 4, characterized in that, The signal preprocessing module includes a filtering submodule and an amplification submodule; The filtering submodule is used to filter the signal light to obtain the filtered signal light; The amplification submodule is used to amplify the filtered signal light to obtain the denoised signal light.

6. A continuous-variable quantum key modulation system according to claim 2, characterized in that, The system also includes a power monitoring and feedback module; The power monitoring and feedback module is used to measure the power of the signal light after the light intensity is limited in real time and feed it back to the integrated optical power limiting module, so that the integrated optical power limiting module can limit the light intensity of the signal light.

7. A continuous-variable quantum key modulation system according to claim 6, characterized in that, The power monitoring and feedback module includes an optical power measurement submodule and a data transmission submodule; The optical power measurement submodule is used to measure the power of the signal light after the light intensity is limited in real time; The data transmission submodule is used to feed back the power feedback information of the light intensity-limited signal light to the integrated optical power limiting module.

8. A continuous-variable quantum key modulation system according to claim 6, characterized in that, The modulation control module includes a parameter setting submodule and a real-time adjustment submodule; The parameter setting submodule is used to receive the modulation command, generate the modulation parameters, and transmit them to the integrated amplitude modulation module. The real-time adjustment submodule is used to obtain the power of the signal light after the light intensity is limited and adjust the modulation parameters, generate the adjusted modulation parameters and transmit them to the integrated amplitude modulation module for the integrated amplitude modulation module to perform all-optical amplitude modulation.

9. A continuous-variable quantum key modulation system according to claim 1, characterized in that, The system also includes a security assessment module; The security assessment module is used to collect the operating data of the integrated amplitude modulation module and the modulation control module in real time, and to analyze and evaluate them in combination with a preset security algorithm.

10. A method for fabricating an optical waveguide unit, characterized in that, The optical waveguide unit integrates a two-dimensional transition metal carbide / nitride Mxene film, and is applied to a continuous-variable quantum key modulation system as described in any one of claims 1-9. The method includes: A solution containing two-dimensional MXene nanosheets was obtained by etching the MAX phase material with LiF / HCl solution. A silica substrate is immersed in the MXene solution for electrostatic adsorption self-assembly to obtain a multilayer MXene film, wherein the silica substrate carries an opposite charge to the MXene solution. Photolithography and dry etching are performed on the silicon dioxide layer of the silicon nitride waveguide to obtain a silicon nitride waveguide with a windowed region, wherein the silicon nitride waveguide is pre-deposited with silicon dioxide to form a silicon dioxide layer; The multilayer Mxene film is coated layer by layer into the windowed area of ​​the silicon nitride waveguide to obtain the optical waveguide unit with integrated two-dimensional transition metal carbide / nitride Mxene film.

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