Satellite-ground QKD synchronization method, device and system integrating beacon light and optical communication

Abstract

The invention discloses a beacon light and optical communication fused satellite-ground QKD (Quantum Key Distribution) synchronization method, which aims at solving the problem that the system complexity and the optical system design difficulty are increased in the existing synchronization method, and comprises the following steps of: generating a synchronization trigger signal at a satellite transmitting end according to a preset period, and generating a synchronization number according to the synchronization trigger signal; superposing the synchronous number into satellite-ground laser communication data and sending the data to a ground receiving end; when the synchronous trigger signal is generated, a beacon light modulation signal is generated in a preset period, and a beacon light pulse is generated according to the beacon light modulation signal and is transmitted to a ground receiving end; analyzing the synchronous number in optical communication at a ground receiving end, detecting the beacon optical pulse, recording the moment when the beacon optical pulse is detected by adopting a time-to-digital converter, and correcting the moment when the beacon optical pulse is detected by adopting a preset algorithm; and completing quantum signal time synchronization in combination with the corrected detection time and the synchronization number. And thus, the purpose of quantum key distribution synchronization is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of satellite-to-ground QKD (quantum key distribution) synchronization, and in particular relates to a satellite-to-ground QKD synchronization method, device and system integrating beacon light and optical communication. Background Art

[0002] Secure and effective key distribution has always been an important research topic in cryptography. Quantum key distribution, as a proven secure key distribution scheme, has been widely verified in experiments. In quantum key distribution, synchronization is essential for the receiver to accurately identify the number of transmitted signals detected by the quantum signal. The synchronization scheme currently used in satellite-to-ground quantum key distribution is the synchronous optical synchronization scheme, which is combined with GPS and satellite-to-ground distance data to achieve synchronization. The implementation process is as follows: The satellite transmitter uses the same clock to modulate the periodic synchronization signal and quantum signal respectively, detects the GPS second pulse recording time at the same time, and sends the GPS second pulse detection time to the receiving end; the ground receiving end detects the synchronization signal, quantum signal and GPS second pulse signal recording time, receives the GPS second pulse detection time from the transmitter, and obtains the changing distance between the satellite and the ground, and finally completes the synchronization of the quantum signal.

[0003] Using the above method, the satellite needs to detect the GPS second pulse time, which requires the satellite to realize the time measurement function, increasing the complexity of the resource-constrained satellite system; the detected GPS second pulse time needs to be sent to the ground receiving end, which increases the amount of data interaction in the satellite-to-ground classical channel with fewer communication resources; finally, the distance between the satellite and the ground must be obtained in order to obtain the synchronous optical transmission time, which increases the dependence on external data and the complexity of system design.

[0004] The prior art provides a method and system for time synchronization in quantum secure communication. The transmitting end labels each signal light according to the time interval between the signal light and the synchronization light of the frame to which it belongs. The receiving end measures the time interval between the signal light and the synchronization light of the frame to which it belongs, and determines the number of the received signal light according to the time interval, and matches the received signal light number with the transmitted signal light number one by one, and then corrects the time position of the signal light through the correction module. This solution belongs to adding an external synchronization light and is suitable for optical fiber channels. However, for free-space laser communication scenarios, the transmitting end already has communication light and beacon light. If an additional synchronization light is added, the optical path structure and hardware design will become more complicated, and the resource usage of the transmitting end will increase. For satellite-to-ground communication scenarios that have more stringent requirements on the size and weight of the device, adding external synchronization light is even more unfavorable to the design of satellite payloads.

[0005] The prior art also provides a satellite-ground quantum key distribution synchronization method based on aperiodic synchronous light. The transmitting end encodes a random sequence into synchronous optical pulses, transmits aperiodic synchronous light, and the receiving end performs synchronous light matching to achieve quantum signal synchronization. However, this method requires the transmitting end to add software and hardware for aperiodic signal modulation, and the ground end needs to add a matching module, making the system more complex. Summary of the Invention

[0006] The object of the present invention is to provide a satellite-ground QKD synchronization method that integrates beacon light and optical communication, which directly uses beacon light without adding additional synchronous light, avoids adding extra hardware, and reduces the resource consumption at the transmitting end.

[0007] To solve the above problems, the technical solution of the present invention is as follows: A satellite-ground QKD synchronization method that integrates beacon light and optical communication, including: Generating a synchronous trigger signal at a preset period at the satellite transmitting end, generating a synchronous number according to the synchronous trigger signal, and superimposing the synchronous number on the satellite-ground laser communication data and sending it to the ground receiving end; while generating the synchronous trigger signal, generating a beacon light modulation signal at a preset period, generating beacon light pulses according to the beacon light modulation signal, and transmitting them to the ground receiving end; At the ground receiving end, parsing the synchronous number in the optical communication, detecting the beacon light pulses, and using a time-to-digital converter to record the moment when the beacon light pulses are detected, and correcting the moment when the beacon light pulses are detected with a preset algorithm; combining the corrected detection moment and the synchronous number to complete the quantum signal time synchronization.

[0008] According to an embodiment of the present invention, further including correcting the moment when the beacon light pulses are detected with a preset algorithm: Modeling the communication delay and its change rate through satellite ephemeris data and performing normalization processing; Fitting the normalized data to generate an initial curve; As the beacon light pulses are input, dynamically optimizing the fitting curve to gradually improve the time correction accuracy; Based on the fitting curve, correcting the arrival moment of the beacon light to obtain a sequence of corrected beacon light arrival moments.

[0009] According to an embodiment of the present invention, further including modeling the communication delay and its change rate through satellite ephemeris data and performing normalization processing: According to the satellite ephemeris data, calculating the function of the distance between the satellite and the ground changing with time during the establishment of the link between the satellite and the ground station ; Based on the function , calculating the function of the communication delay from the satellite to the ground station changing with time: where c is the speed of light; calculate the first derivative of, and obtain ; For calculate the maximum value and the minimum value, and obtain and ; Normalize to obtain the normalized function:

[0010] According to an embodiment of the present invention, further comprising: fitting the normalized data to generate an initial curve For perform curve fitting to obtain the fitted curve ; The ground receiving station receives N beacon optical pulses and records the arrival times of each beacon optical pulse; Calculate the intervals between the arrival times of adjacent pulses among the N beacon optical pulses ; For each perform normalization to obtain ; Taking the moment when the agreed start key distribution starts as the moment t = 0, the time values of each beacon optical pulse relative to the moment t = 0 are obtained, and is expressed as an interval characterized by the time value , and multiple points with the time value as the horizontal axis and as the vertical axis are obtained; Find the optimal values for the parameters of the curve for the said multiple points, and perform curve fitting to obtain the initial curve.

[0011] According to an embodiment of the present invention, further comprising: dynamically optimizing the fitted curve as the beacon optical pulses are input When a new beacon optical pulse arrives, select k - 1 points, find the optimal values based on the parameters of the initial curve, and re - fit to obtain a new fitted curve.

[0012] According to an embodiment of the present invention, further comprising: correcting the arrival times of the beacon light based on the fitted curve to obtain a sequence of corrected arrival times of the beacon light On the new fitted curve, from obtain the time interval value between the arrival time of the k - th beacon optical pulse and the arrival time of the (k - 1)-th beacon optical pulse ; For calculate the value restored to the non - normalized state: According to Obtain the arrival time of the k-th beacon light after correction: After each beacon light pulse arrives, repeat the above steps to obtain a sequence, which is used as the sequence of the arrival times of the corrected beacon lights.

[0013] A satellite-ground QKD synchronization device that integrates beacon light and optical communication, comprising: A signal transmission module, configured to generate a synchronization trigger signal at a preset period at the satellite transmitting end, generate a synchronization number according to the synchronization trigger signal, and superimpose the synchronization number on the satellite-ground laser communication data and send it to the ground receiving end; while generating the synchronization trigger signal, generate a beacon light modulation signal at a preset period, generate a beacon light pulse according to the beacon light modulation signal, and transmit it to the ground receiving end; A signal receiving module, configured to parse the synchronization number in the optical communication at the ground receiving end, detect the beacon light pulse, and use a time-to-digital converter to record the time when the detected beacon light pulse arrives, and correct the time when the detected beacon light pulse arrives with a preset algorithm; combine the corrected detection time and the synchronization number to complete the time synchronization of the quantum signal.

[0014] A satellite-ground QKD synchronization system, applying the satellite-ground QKD synchronization method that integrates beacon light and optical communication, comprising: a spaceborne transmission system, a ground receiving system, and a signal processing system; Among them, the spaceborne transmission system includes a quantum light source, a beacon light source, a quantum encoding module, a modulation module, a main control module, and a transmitting mirror group; the quantum light source emits quantum light, which is encoded by the quantum encoding module to generate an optical quantum wave packet containing quantum key information; the main control module generates an electrical pulse signal, and the modulation module modulates the beacon light source to emit pulsed beacon light; the beacon light is emitted by the transmitting mirror group and transmitted to the ground receiving system through the satellite-ground free space channel; The ground receiving system includes a receiving mirror group, a beam splitter, a beam splitter, a pointing control module, a quantum decoding module, a first detector, and a second detector; the beacon light and quantum light received by the receiving mirror group enter the quantum decoding module through the beam splitter; the beacon light is split into two by the beam splitter, one path is received by the first detector and enters the pointing control module to correct the pointing of the ground receiving mirror group in real time to ensure that the quantum light emitted by the satellite can be stably received by the ground; the other path is detected by the second detector, and the photoelectric conversion outputs an electrical signal and enters the signal processing system; The signal processing system includes a time-to-digital converter and a time correction module, and outputs a stable and low-jitter synchronization signal after preset processing for the quantum decoding module to perform basis vector comparison, so as to complete the synchronization of quantum key distribution.

[0015] Due to the adoption of the above technical solutions, the present invention has the following advantages and positive effects compared with the prior art: In a satellite-ground QKD synchronization method for the fusion of beacon light and optical communication according to an embodiment of the present invention, in view of the problem that the existing synchronization method will increase the system complexity and the difficulty of optical system design, which is not conducive to the combination with the existing space laser communication system, a synchronization trigger signal is generated at the satellite transmitting end at a preset period, a synchronization number is generated according to the synchronization trigger signal, and the synchronization number is superimposed on the satellite-ground laser communication data and sent to the ground receiving end; while generating the synchronization trigger signal, a beacon light modulation signal is generated at a preset period, a beacon light pulse is generated according to the beacon light modulation signal, and is transmitted to the ground receiving end; at the ground receiving end, the synchronization number in the optical communication is parsed, the beacon light pulse is detected, and a time-to-digital converter is used to record the moment when the beacon light pulse is detected, and a preset algorithm is used to correct the moment when the beacon light pulse is detected; combining the corrected detection moment and the synchronization number to complete the time synchronization of the quantum signal; thereby achieving the purpose of realizing the synchronization of quantum key distribution by using the existing beacon light source of the space laser communication system. Brief Description of the Drawings

[0016] Figure 1 is a signal flow diagram of a satellite-ground QKD synchronization method for the fusion of beacon light and optical communication according to an embodiment of the present invention; Figure 2 is a block diagram of a satellite-ground QKD synchronization system according to an embodiment of the present invention. Detailed Embodiments

[0017] The following further describes in detail a satellite-ground QKD synchronization method, device and system for the fusion of beacon light and optical communication proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. According to the following description and the claims, the advantages and features of the present invention will be clearer.

[0018] Since the existing satellite-ground QKD synchronization method will increase the system complexity by adding an external synchronization light, such as adding a strong laser, which increases the cost of the equipment and requires a separate wavelength band, increasing the difficulty of the overall optical system design and being not conducive to the combination with the existing space laser communication system. This embodiment provides a satellite-ground QKD synchronization method for the fusion of beacon light and optical communication, which realizes the synchronization of quantum key distribution by using the existing beacon light source of the space laser communication system, without adding an external synchronization light, directly using the beacon light, making the optical and structural design simple, the system lightweight, and reducing the resource usage at the transmitting end.

[0019] The satellite-ground QKD synchronization method for the fusion of beacon light and optical communication includes: At the satellite transmitting end, a synchronous trigger signal is generated at a preset period, a synchronous number is generated according to the synchronous trigger signal, and the synchronous number is superimposed on the satellite-ground laser communication data and sent to the ground receiving end; while generating the synchronous trigger signal, a beacon light modulation signal is generated at a preset period, a beacon light pulse is generated according to the beacon light modulation signal, and is transmitted to the ground receiving end; At the ground receiving end, the synchronous number in the optical communication is parsed, the beacon light pulse is detected, and the time digital converter is used to record the time when the beacon light pulse is detected, and the time when the detected beacon light pulse is corrected by a preset algorithm; combining the corrected detection time and the synchronous number to complete the time synchronization of the quantum signal.

[0020] Specifically, please refer to Figure 1 , the satellite transmitting end includes a quantum unit, a communication processor and a beacon light transmitting unit, and the ground receiving end includes a communication processor, a quantum unit and a beacon light TDC measurement unit. The satellite-ground QKD synchronization process is divided into synchronous coding coarse synchronization and beacon light fine synchronization, which mainly includes the following steps: Satellite transmitting end: 1. Synchronous coding coarse synchronization: The quantum unit on the satellite generates a synchronous trigger signal at a certain period and sends it to the communication processor. The communication processor generates a synchronous number according to the synchronous trigger signal, superimposes the synchronous number on the satellite-ground laser communication data, and sends it to the ground receiving end through laser communication.

[0021] 2. Beacon light fine synchronization: While generating the synchronous trigger signal, the quantum unit generates a beacon light modulation signal at a certain period and sends it to the beacon light transmitting unit. The beacon light transmitting unit generates a beacon light pulse according to the modulation signal and transmits it to the ground receiving end.

[0022] Ground receiving end: 1. The communication processor at the receiving end parses the synchronous number in the optical communication and transmits the synchronous number to the quantum unit.

[0023] 2. The beacon light TDC measurement unit at the receiving end detects the beacon light signal, and uses the time digital converter TDC to obtain the time when the beacon light pulse is detected at the receiving end, and then corrects the detection time.

[0024] 3. The quantum unit completes the time synchronization of the quantum signal by combining the corrected time value and the synchronous sequence number.

[0025] Among them, the correction of the time when the detected beacon light pulse is further included by a preset algorithm: Model the communication delay and its change rate through satellite ephemeris data and perform normalization processing; Fit the normalized data to generate an initial curve; With the input of the beacon light pulse, dynamically optimize the fitting curve and gradually improve the time correction accuracy; Based on the fitting curve, correct the arrival time of the beacon light to obtain the corrected sequence of the arrival time of the beacon light.

[0026] Specifically, modeling the communication delay and its change rate through satellite ephemeris data, and further including normalization processing: According to the satellite ephemeris data, calculate the function of the distance between the satellite and the ground changing with time during the establishment of the link between the satellite and the ground station ; Based on the function , calculate the function of the communication delay from the satellite to the ground station changing with time: where c is the speed of light; calculate the first derivative of, to obtain ; For calculate the maximum value and the minimum value to obtain and ; Normalize to obtain the normalized function:

[0027] Further including curve fitting for the normalized data to generate an initial curve: For perform curve fitting to obtain the fitting curve ; The ground receiving station receives N beacon light pulses and records the arrival time of each beacon light pulse; Calculate the interval between the arrival times of two adjacent pulses among the N beacon light pulses ; For each perform normalization to obtain ; The normalization calculation formula is: ; Taking the moment when the agreed start key distribution occurs as the moment of t = 0, the time value of each beacon light pulse relative to the moment of t = 0 is obtained, and is expressed as an interval characterized by the time value , to obtain multiple points with the time value as the horizontal axis and as the vertical axis; Find the optimal value for the parameters of the curve for the said multiple points, perform curve fitting to obtain the initial curve.

[0028] Further including dynamically optimizing the fitting curve with the input of beacon light pulses: After a new beacon optical pulse arrives, k - 1 points are selected, and the optimal values are searched based on the parameters of the initial curve, and a new fitted curve is obtained by refitting. For example, as the kth (k > N) beacon optical pulse arrives, calculate , and then convert it to . For the to , a total of k - 1 points, according to the parameters of the previous curve fitting, search for the optimal values nearby, and fit to obtain a new fitted curve.

[0029] Based on the fitted curve, correct the arrival time of the beacon optical signal, and the obtained corrected arrival time sequence of the beacon optical signal further includes: On the new fitted curve, from , obtain the time interval value between the arrival time of the kth beacon optical pulse and the arrival time of the (k - 1)th beacon optical pulse ; The subscript 2 indicates that this value is obtained from the fitted curve.

[0030] For , calculate the value restored to before normalization: According to , obtain the corrected arrival time of the kth beacon optical signal: After each beacon optical pulse arrives, repeat the above steps to obtain sequence, as the corrected arrival time sequence of the beacon optical signal.

[0031] The corrected arrival time of the beacon optical signal, compared with that before correction, the time jitter caused by factors such as atmospheric fluctuations, light source jitter, and detector jitter will be greatly reduced, so that it can be applied to quantum key synchronization.

[0032] In summary, the space - to - ground QKD synchronization method integrating the beacon optical signal and optical communication has the following advantages: Accurate time correction: Through dynamic curve fitting, the arrival time of the beacon optical signal can be accurately corrected, reducing the time jitter caused by factors such as atmospheric fluctuations, light source jitter, and detector jitter, so as to achieve high - precision time synchronization and provide a stable time reference for quantum key distribution.

[0033] Adapt to complex environments: This method can adapt to the complex optical link environment in space - to - ground quantum key distribution, such as time drift and signal loss caused by the Doppler effect, ensuring high - precision time synchronization can still be maintained under unstable link conditions.

[0034] No additional synchronization device: Compared with traditional methods such as GPS pulses and synchronous optical external synchronization, this method does not require additional GPS devices or synchronous light, reducing the hardware requirements and costs of the system and facilitating the miniaturization and integration of quantum key distribution devices.

[0035] Real-time dynamic adjustment: As beacon light pulses arrive continuously, the fitting curve can be adjusted dynamically in real time, gradually optimizing the time correction result, enabling the system to quickly adapt to link changes and improving the stability and reliability of time synchronization.

[0036] Continuous performance optimization: By continuously receiving new beacon light pulses and updating the fitting curve, the accuracy of time correction can be continuously optimized to ensure that the system maintains high-precision time synchronization during long-term operation.

[0037] Effective interference suppression: By correcting the arrival time of beacon light through the fitting curve, the influence of external interference on time synchronization, such as atmospheric fluctuations and light source jitter, can be effectively suppressed, improving the anti-interference ability of the system and ensuring the stability and security of quantum key distribution.

[0038] Stable key distribution: High-precision time synchronization can ensure a one-to-one mapping of quantum signals between the transmitter and receiver during quantum key distribution, reducing the bit error rate caused by time jitter and improving the stability and reliability of key distribution.

[0039] Long-term continuous operation: This method supports long-term continuous operation of the system. By accumulating multiple frames of detection events, there is no need to increase the length of the synchronization string to compensate for channel loss, improving the stability and practicality of the system.

[0040] Based on the above concept, this embodiment also provides a satellite-ground QKD synchronization device that integrates beacon light and optical communication, including: A signal transmission module, configured to generate a synchronization trigger signal at a preset period at the satellite transmitter end, generate a synchronization number according to the synchronization trigger signal, superimpose the synchronization number on the satellite-ground laser communication data and send it to the ground receiver end; while generating the synchronization trigger signal, generate a beacon light modulation signal at a preset period, generate beacon light pulses according to the beacon light modulation signal, and transmit them to the ground receiver end; A signal reception module, configured to parse the synchronization number in the optical communication at the ground receiver end, detect the beacon light pulses, record the time when the detected beacon light pulses are detected using a time-to-digital converter, and correct the time when the detected beacon light pulses are detected using a preset algorithm; combine the corrected detection time and the synchronization number to complete quantum signal time synchronization.

[0041] It can be understood that the signal transmission module completes the synchronous trigger signal generated by the quantum unit in the satellite transmission end, and the communication processor generates a synchronous number according to the synchronous trigger signal; and while the quantum unit generates the synchronous trigger signal, it also generates a beacon light modulation signal. The beacon light transmission unit generates a beacon light pulse according to the modulation signal and transmits it to the ground receiving end.

[0042] Similarly, the signal receiving module completes the functions implemented by the ground receiving end.

[0043] The above satellite-ground QKD synchronization method integrating beacon light and optical communication can be applied to the following satellite-ground QKD synchronization system to realize the synchronization of satellite-ground quantum key distribution. Please refer to Figure 2 , and this satellite-ground QKD synchronization system includes: a spaceborne emission system, a ground receiving system, and a signal processing system; Among them, the spaceborne emission system includes a quantum light source, a beacon light source, a quantum encoding module, a modulation module, a main control module, and a transmitting mirror group; the quantum light source emits quantum light, which is encoded by the quantum encoding module to generate an optical quantum wave packet containing quantum key information; the main control module generates an electrical pulse signal, and the modulation module modulates the beacon light source to emit a pulsed beacon light; the beacon light is emitted by the transmitting mirror group and transmitted to the ground receiving system through the satellite-ground free space channel; The ground receiving system includes a receiving mirror group, a beam splitter, a beam splitter, a pointing control module, a quantum decoding module, a first detector, and a second detector; the beacon light and quantum light received by the receiving mirror group pass through the beam splitter, and the quantum light enters the quantum decoding module; the beacon light is split into two by the beam splitter, one path is received by the first detector and enters the pointing control module to correct the pointing of the ground receiving mirror group in real time to ensure that the quantum light emitted by the satellite can be stably received by the ground; the other path is detected by the second detector, and the photoelectric conversion outputs an electrical signal and enters the signal processing system; The signal processing system includes a time-to-digital converter and a time correction module, which outputs a stable and low-jitter synchronous signal after preset processing for the quantum decoding module to perform basis vector comparison, thereby completing the synchronization of quantum key distribution. This signal processing system realizes the correction of the moment of the detected beacon light pulse with a preset algorithm in the above satellite-ground QKD synchronization method integrating beacon light and optical communication; combines the corrected detection moment and the synchronous number to complete the synchronization of the quantum signal time, and further completes the synchronization of quantum key distribution.

[0044] The embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, provided that these changes fall within the scope of the claims of the present invention and their equivalent technologies, they still fall within the protection scope of the present invention.

Claims

1. A satellite-to-ground QKD synchronization method integrating beacon light and optical communication, characterized in that: include: Generate a synchronization trigger signal at a preset period at the satellite transmitting end, generate a synchronization number according to the synchronization trigger signal, superimpose the synchronization number on the satellite-to-ground laser communication data and send it to the ground receiving end; while generating the synchronization trigger signal, generate a beacon light modulation signal at a preset period, generate a beacon light pulse according to the beacon light modulation signal, and transmit it to the ground receiving end; At the ground receiving end, the synchronization number in the optical communication is parsed, the beacon light pulse is detected, and the time when the beacon light pulse is detected is recorded using a time-to-digital converter. The time when the beacon light pulse is detected is corrected using a preset algorithm; the quantum signal time synchronization is completed by combining the corrected detection time and synchronization number.

2. The satellite-to-ground QKD synchronization method integrating beacon light and optical communication as claimed in claim 1, characterized in that: Correcting the time of detecting the beacon light pulse using a preset algorithm further includes: The communication delay and its rate of change are modeled through satellite ephemeris data and normalized; Fit the normalized data to generate an initial curve; With the input of beacon light pulses, the fitting curve is dynamically optimized to gradually improve the time correction accuracy; The beacon light arrival time is corrected based on the fitting curve to obtain a corrected beacon light arrival time sequence.

3. The satellite-to-ground QKD synchronization method integrating beacon light and optical communication as claimed in claim 2, characterized in that: Modeling the communication delay and its rate of change through satellite ephemeris data and performing normalization further includes: According to the satellite ephemeris data, the function of the distance between the satellite and the ground changing with time during the link establishment between the satellite and the ground station is calculated. ; Function-based , calculate the function of the communication delay from satellite to ground station changing with time: Where c is the speed of light; calculate The first-order derivative of ; right Calculate the maximum and minimum values ​​and get and ; Normalize it and get the normalized function: 。 4. The satellite-to-ground QKD synchronization method integrating beacon light and optical communication as claimed in claim 3, characterized in that: Fitting the normalized data to generate an initial curve further includes: right Perform curve fitting to obtain the fitting curve ; The ground receiving station receives N beacon light pulses and records the arrival time of each beacon light pulse; Calculate the time interval between two adjacent beacon light pulses ; For each Normalize it and get ; Taking the agreed time of starting key distribution as t=0, the time value of each beacon light pulse compared to t=0 is obtained. Represented as an interval represented by a time value , and the horizontal axis is the time value. are multiple points on the vertical axis; For the multiple points on the curve Find the optimal value of the parameters, perform curve fitting, and obtain the initial curve.

5. The satellite-to-ground QKD synchronization method integrating beacon light and optical communication as claimed in claim 4, characterized in that: With the input of the beacon light pulse, the dynamic optimization fitting curve further includes: When a new beacon light pulse arrives, k-1 points are selected, the optimal values ​​are found based on the parameters of the initial curve, and a new fitting curve is obtained by refitting.

6. The satellite-to-ground QKD synchronization method integrating beacon light and optical communication as claimed in claim 5, characterized in that: Correcting the beacon light arrival time based on the fitting curve to obtain a corrected beacon light arrival time sequence further includes: On the new fitting curve, Get the time interval between the arrival time of the kth beacon light pulse and the arrival time of the k-1th beacon light pulse ; right Calculate the value before normalization: according to Get the corrected arrival time of the kth beacon light: After each beacon light pulse arrives, repeat the above steps to get sequence, as the corrected beacon light arrival time sequence.

7. A satellite-to-ground QKD synchronization device integrating beacon light and optical communication, characterized in that: include: The signal transmission module is configured to generate a synchronization trigger signal at a preset period at the satellite transmitting end, generate a synchronization number according to the synchronization trigger signal, superimpose the synchronization number on the satellite-to-ground laser communication data and send it to the ground receiving end; while generating the synchronization trigger signal, generate a beacon light modulation signal at a preset period, generate a beacon light pulse according to the beacon light modulation signal, and transmit it to the ground receiving end; The signal receiving module is configured to parse the synchronization number in the optical communication at the ground receiving end, detect the beacon light pulse, and use a time-to-digital converter to record the time when the beacon light pulse is detected, and correct the time when the beacon light pulse is detected using a preset algorithm; combined with the corrected detection time and synchronization number, the quantum signal time synchronization is completed.

8. A satellite-to-ground QKD synchronization system, using the satellite-to-ground QKD synchronization method integrating beacon light and optical communication as described in any one of claims 1 to 6, characterized in that: include: Satellite-borne transmission system, ground receiving system and signal processing system; The satellite-borne transmission system includes a quantum light source, a beacon light source, a quantum coding module, a modulation module, a main control module and a transmitting mirror group; the quantum light source transmits quantum light, which is encoded by the quantum coding module to generate a light quantum wave packet containing quantum key information; the main control module generates an electrical pulse signal, and the modulation module modulates the beacon light source to emit pulsed beacon light; the beacon light is emitted by the transmitting mirror group and transmitted to the ground receiving system via the satellite-to-ground free space channel; The ground receiving system includes a receiving mirror group, a spectroscope, a beam splitter, a pointing control module, a quantum decoding module, a first detector, and a second detector; the beacon light and quantum light received by the receiving mirror group pass through the spectroscope, and the quantum light enters the quantum decoding module; the beacon light is split into two by the beam splitter, one of which is received by the first detector and enters the pointing control module to correct the pointing of the ground receiving mirror group in real time to ensure that the quantum light emitted by the satellite can be stably received by the ground; the other is detected by the second detector, and the photoelectric conversion output electrical signal enters the signal processing system; The signal processing system includes a time-to-digital converter and a time correction module, which output a stable, low-jitter synchronization signal after preset processing for the quantum decoding module to perform basis vector comparison, thereby completing the synchronization of quantum key distribution.

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