CN-121984677-A - Quantum key distribution and classical optical communication common fiber transmission system and method

CN121984677ACN 121984677 ACN121984677 ACN 121984677ACN-121984677-A

Abstract

The invention relates to quantum key distribution, in particular to a quantum key distribution and classical optical communication fiber sharing transmission system and method, wherein a signal sending unit generates and sends quantum optical signals and classical optical signals, a channel parameter adjusting unit adjusts and controls the power and delay of the classical optical signals so as to reduce fiber sharing interference, a wavelength division multiplexing transmission unit merges, transmits and separates the quantum optical signals and the adjusted classical optical signals, a signal receiving unit receives the separated optical signals and decodes, detects or measures the separated optical signals, and a control center is used as a core decision and coordination unit of the system to realize state monitoring, data analysis and flow scheduling of the system through staged control.

Inventors

HAO PENGLEI
LIU YUN
CAO YUAN
LIU JINGJING
SHI HONGQI

Assignees

安徽问天量子科技股份有限公司

Dates

Publication Date: 20260505
Application Date: 20260318

Claims (10)

1. The quantum key distribution and classical optical communication common fiber transmission system is characterized by comprising a signal sending unit, a channel parameter adjusting unit, a wavelength division multiplexing transmission unit, a signal receiving unit and a control center; A signal transmitting unit that generates and transmits a quantum optical signal and a classical optical signal; The channel parameter adjusting unit is used for adjusting and controlling the power and the time delay of the classical optical signals so as to reduce the co-fiber interference; The wavelength division multiplexing transmission unit is used for combining, transmitting and separating the quantum optical signals and the regulated classical optical signals; a signal receiving unit for receiving the separated optical signal and performing decoding, detection or measurement; the control center is used as a core decision and coordination unit of the system, and the state monitoring, the data analysis and the flow scheduling of the system are realized through staged control.
2. The quantum key distribution and classical optical communication co-fiber transmission system according to claim 1, wherein the signal transmitting unit comprises a QKD transmitting end and a classical optical communication transmitting end; the QKD transmitting end generates a quantum optical signal, and the coding information is loaded on the quantum state of the photon; and the classical optical communication transmitting end generates multiple classical optical signals with different wavelengths and is used for carrying the transmission of different service data.
3. The quantum key distribution and classical optical communication co-fiber transmission system according to claim 2, wherein the channel parameter adjusting unit comprises an electrically controlled adjustable attenuator and a phase shifter; The electric control adjustable attenuator is used for realizing power regulation and control of classical optical signals by adjusting the light attenuation; The phase shifter is used for realizing delay regulation and control of classical optical signals by adjusting transmission phases, so that the classical optical signals and the quantum optical signals are staggered in the time domain.
4. The quantum key distribution and classical optical communication co-fiber transmission system according to claim 3, wherein the wavelength division multiplexing transmission unit comprises a wavelength division multiplexer, a transmission optical fiber and a wavelength division demultiplexer; The wavelength division multiplexer is used for combining the quantum optical signals and the regulated classical optical signals; The transmission optical fiber carries long-distance transmission of the combined optical signal; the wavelength division demultiplexer re-separates the combined optical signal into an independent quantum optical signal and a classical optical signal.
5. The quantum key distribution and classical optical communication co-fiber transmission system according to claim 4, wherein the signal receiving unit comprises a QKD receiving end, an optical power meter, a classical optical communication receiving end and an optical switch; the QKD receiving end performs quantum state decoding and detection on the received quantum optical signals, calculates an error rate QBER according to the time block and uploads the error rate QBER to the control center; The optical power meter is used for measuring the power value of the classical optical signal and uploading the power value to the control center; The classical optical communication receiving end processes the received classical optical signal; The optical switch is used for switching the classical optical path under the control of the control center and guiding the classical optical signal to the optical power meter or the classical optical communication receiving end; the time block is obtained by dividing one operation period into a plurality of continuous time periods, and each time block independently calculates the error rate QBER.
6. The quantum key distribution and classical optical communication co-fiber transmission system according to claim 5, wherein the control center monitors the state of the system, analyzes data and schedules the flow through staged control: in the initialization stage, an optical power adjustment mechanism and a time domain staggering mechanism are executed, an optimal optical power parameter and an optimal delay parameter are respectively determined, meanwhile, an operation period is divided into continuous time blocks, an error code screening mechanism is executed, and validity judgment and initial marking are carried out on each time block according to an error code rate QBER uploaded by a QKD receiving end; And in the quantum key distribution stage, continuously receiving the bit error rate QBER uploaded by the QKD receiving end, executing an error code screening mechanism, performing bit error rate recalculation, validity compounding and mark updating on the time block marked as invalid in the last operation period, and performing data classification processing and system performance monitoring.
7. The quantum key distribution and classical optical communication common fiber transmission method is applied to the quantum key distribution and classical optical communication common fiber transmission system as claimed in claim 1, and is characterized by comprising the following steps: An initialization stage: S1, a signal sending unit generates and sends a quantum optical signal and a classical optical signal, a control center controls an optical switch to guide the classical optical signal in a signal receiving unit to an optical power meter, an optical power adjusting mechanism is executed, and after an optimal optical power parameter A_opt is locked through an electric control adjustable attenuator, the control center controls the optical switch to guide the classical optical signal in the signal receiving unit to a classical optical communication receiving end; S2, the control center executes a time domain staggering mechanism, and locks the optimal delay parameter through the phase shifter ; S3, the QKD receiving end performs quantum state decoding and detection on the received quantum optical signals, the control center divides an operation period into a plurality of continuous time blocks, an error code screening mechanism is executed, validity judgment and initial marking are performed on each time block according to the error code rate QBER uploaded by the QKD receiving end, time block data marked as valid enter a key generation flow, and time block data marked as invalid are discarded; quantum key distribution phase: S4, the signal sending unit is based on the optimal optical power parameter A_opt and the optimal delay parameter Continuously generating and transmitting quantum optical signals and classical optical signals, and combining, transmitting and separating by a wavelength division multiplexing transmission unit; S5, the QKD receiving end carries out quantum state decoding and detection on the received quantum optical signals, the control center continuously receives the bit error rate QBER uploaded by the QKD receiving end, an error code screening mechanism is executed, bit error rate recalculation, validity compounding and mark updating are carried out on the time block marked as invalid in the previous operation period, the time block data marked as valid enters a key generation flow, and bit error rate information of the time block data marked as invalid is maintained for system performance monitoring; The classical optical communication receiving end normally receives and processes classical optical signals in the whole stage.
8. The quantum key distribution and classical optical communication co-fiber transmission method of claim 7, wherein the specific process of the optical power adjustment mechanism comprises the following steps: S11, setting an optical power target, namely setting an initial optical attenuation A_min, a target receiving power interval [ P min ,P max ] and adjusting a stepping of the electrically-controlled adjustable attenuator The control center controls the optical switch to guide classical optical signals in the signal receiving unit to the optical power meter; s12, adjusting and locking the optical power, namely controlling the center to adjust the stepping The method comprises the steps of gradually adjusting light attenuation, synchronously reading a current light power value P_cur uploaded by an optical power meter, stopping adjusting when the current light power value P_cur falls into a target receiving power interval [ P min ,P max ], locking the current light attenuation into an optimal light power parameter A_opt, controlling an optical switch to guide a classical light signal in a signal receiving unit to a classical light communication receiving end, and finishing light power adjustment; The optical power adjusting mechanism adjusts and maintains the power of the classical optical signal received by the classical optical communication receiving end in a target receiving power interval [ P min ,P max ] through the cooperative work of the control center, the electric control adjustable attenuator, the optical power meter and the optical switch so as to reduce nonlinear interference on a quantum channel, and the mechanism is triggered and executed when the system is powered on or reset.
9. The quantum key distribution and classical optical communication co-fiber transmission method of claim 7, wherein the specific process of the time domain staggering mechanism comprises the following steps: s21, setting scanning parameters, namely setting the delay scanning range of the phase shifter as [0, T_q ] and setting the scanning stepping simultaneously by taking the quantum light pulse period T_q as a reference by the control center ; S22, delay adjustment and locking, wherein the control center drives the phase shifter to step according to scanning Step-by-step delay scanning is carried out, at each delay point, a control center receives the error rate QBER or detection event count uploaded by a QKD receiving end, and the optimal delay parameters are locked : When the error rate QBER is used as a criterion, the delay corresponding to the lowest point of the error rate is locked as the optimal delay parameter ; When the detected event count is taken as a criterion, the delay corresponding to the lowest point of the detected event count is locked as the optimal delay parameter ; The time domain staggering mechanism adjusts the transmission delay of the classical optical signal through the cooperative work of the control center, the phase shifter and the QKD receiving end, so that the classical optical signal and the quantum optical signal are staggered in the time domain, the time domain overlapping interference is reduced, and the mechanism is triggered to be executed when the system is powered on or reset.
10. The method for quantum key distribution and classical optical communication co-fiber transmission according to claim 7, wherein the specific process of the error code screening mechanism in the initialization stage comprises: The QKD receiving end discloses all initial detection results, calculates the error rate QBER of each time block according to the time blocks divided by the control center, uploads the error rate QBER to the control center, and the control center judges: If the bit error rate QBER is not greater than the bit error rate threshold QBER_th, namely QBER is less than or equal to QBER_th, marking the time block data as valid, and informing a QKD receiving end of using the time block data; If the error rate QBER is greater than the error rate threshold QBER_th, namely QBER > QBER_th, marking the time block data as invalid, and informing the QKD receiving end of discarding the time block data; The specific process of the error code screening mechanism in the quantum key distribution stage comprises the following steps: after the system starts quantum key distribution, monitoring the time block data marked as invalid, continuously receiving the bit error rate QBER uploaded by the QKD receiving end, and performing bit error rate recalculation, validity compounding and mark updating on the time block marked as invalid in the last operation period: If the bit error rate QBER is not greater than the bit error rate threshold QBER_th, namely QBER is less than or equal to QBER_th, marking the time block data as valid, and informing a QKD receiving end of using the time block data; If the bit error rate QBER is greater than the bit error rate threshold QBER_th, namely QBER > QBER_th, marking the time block data as invalid, maintaining bit error rate information of the invalid marked time block data for monitoring system performance, and re-entering the re-evaluation queue in the next operation period.

Description

Quantum key distribution and classical optical communication common fiber transmission system and method Technical Field The invention relates to quantum key distribution, in particular to a quantum key distribution and classical optical communication common fiber transmission system and method. Background Quantum Key Distribution (QKD) is a symmetric key distribution technique based on quantum mechanics principles that achieves theoretically provable security. In order to reduce the special optical fiber deployment cost and promote the large-scale application of the QKD technology, the common fiber transmission of the quantum optical signal and the classical optical signal in the same optical fiber becomes an attractive solution. However, this approach faces the core challenge that QKD technology handles optical signals on the order of single photons, while the classical optical signal power of co-transmission is typically over several orders of magnitude higher. The huge power difference not only puts high requirements on the signal isolation technology, but also causes broadband scattering in the optical fiber due to nonlinear effects such as Raman scattering, four-wave mixing and the like of classical optical signals, so that the error rate is increased, even key negotiation failure is caused, and the normal operation of QKD is seriously affected. In order to cope with interference caused by co-fiber transmission, three technical paths of wavelength division multiplexing, time division multiplexing and space division multiplexing are mainly proposed at present. Wavelength division multiplexing realizes co-transmission through wavelength isolation, deployment is convenient, but a filter has limited isolation capability, is difficult to completely filter out leakage light, and cannot inhibit the influence of nonlinear noise on a quantum wave band. The time division multiplexing alternately transmits signals in the time domain, and can avoid co-transmission interference, but has extremely high requirements on time slot synchronization precision, is easily influenced by working environment to generate time delay drift, and has higher requirements on response speed of a detector particularly at high communication speed, and has great engineering realization difficulty and limited application. Space division multiplexing utilizes multi-core or multi-mode optical fibers to provide independent space channels to realize physical isolation, has excellent performance, but needs to replace the existing optical cable, has higher deployment cost, and is difficult to popularize and apply in the existing widely deployed single-mode optical fiber network. Disclosure of Invention (One) solving the technical problems Aiming at the defects existing in the prior art, the invention provides a quantum key distribution and classical optical communication co-fiber transmission system and method, which can effectively overcome the defects of reduced key distribution quality and reduced key generation rate caused by co-fiber transmission of quantum optical signals and classical optical signals existing in the prior art. (II) technical scheme In order to achieve the above purpose, the invention is realized by the following technical scheme: a quantum key distribution and classical optical communication common fiber transmission system comprises a signal sending unit, a channel parameter adjusting unit, a wavelength division multiplexing transmission unit, a signal receiving unit and a control center; A signal transmitting unit that generates and transmits a quantum optical signal and a classical optical signal; The channel parameter adjusting unit is used for adjusting and controlling the power and the time delay of the classical optical signals so as to reduce the co-fiber interference; The wavelength division multiplexing transmission unit is used for combining, transmitting and separating the quantum optical signals and the regulated classical optical signals; a signal receiving unit for receiving the separated optical signal and performing decoding, detection or measurement; the control center is used as a core decision and coordination unit of the system, and the state monitoring, the data analysis and the flow scheduling of the system are realized through staged control. Preferably, the signal transmitting unit comprises a QKD transmitting end and a classical optical communication transmitting end; the QKD transmitting end generates a quantum optical signal, and the coding information is loaded on the quantum state of the photon; and the classical optical communication transmitting end generates multiple classical optical signals with different wavelengths and is used for carrying the transmission of different service data. Preferably, the channel parameter adjusting unit comprises an electrically controlled adjustable attenuator and a phase shifter; The electric control adjustable attenuator is used for realizing power regu