CN116418408A - Signal light pulse position determining method, system, transmitting end and receiving end - Google Patents

Signal light pulse position determining method, system, transmitting end and receiving end Download PDF

Info

Publication number
CN116418408A
CN116418408A CN202111674739.7A CN202111674739A CN116418408A CN 116418408 A CN116418408 A CN 116418408A CN 202111674739 A CN202111674739 A CN 202111674739A CN 116418408 A CN116418408 A CN 116418408A
Authority
CN
China
Prior art keywords
light pulse
synchronous
synchronization
signal
pulse
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202111674739.7A
Other languages
Chinese (zh)
Inventor
唐世彪
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Quantumctek Co Ltd
Original Assignee
Quantumctek Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Quantumctek Co Ltd filed Critical Quantumctek Co Ltd
Priority to CN202111674739.7A priority Critical patent/CN116418408A/en
Publication of CN116418408A publication Critical patent/CN116418408A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/40—Transceivers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/50—Transmitters
    • H04B10/508—Pulse generation, e.g. generation of solitons
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/70—Photonic quantum communication
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H04J14/0201—Add-and-drop multiplexing
    • H04J14/0202—Arrangements therefor
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J3/00—Time-division multiplex systems
    • H04J3/02—Details
    • H04J3/06—Synchronising arrangements
    • H04J3/0602—Systems characterised by the synchronising information used
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J3/00—Time-division multiplex systems
    • H04J3/02—Details
    • H04J3/06—Synchronising arrangements
    • H04J3/0635—Clock or time synchronisation in a network
    • H04J3/0676—Mutual
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
    • H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
    • H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
    • H04L9/0852—Quantum cryptography
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optics & Photonics (AREA)
  • Theoretical Computer Science (AREA)
  • Computer Security & Cryptography (AREA)
  • Optical Communication System (AREA)

Abstract

The application provides a method, a system, a transmitting end and a receiving end for determining the position of a signal light pulse, wherein the method comprises the following steps: the receiving end generates a notification message based on the first synchronous light pulse from the transmitting end; when the sending end receives the notification message and the set number of first synchronous light pulses are sent, the signal light pulses and the second synchronous light pulses are combined; the receiving end divides and converts the combined signal light pulse and the second synchronous light pulse into electric signal forms, and for the second synchronous light pulse of each electric signal form, the time difference value between each signal light pulse under the second synchronous light pulse and the second synchronous light pulse is measured, and each signal light pulse under the second synchronous light pulse is classified to the second synchronous light pulse according to the measured time difference value and the synchronous light time interval so as to obtain the position information of the signal light pulse under the second synchronous light pulse. The method and the device can correctly classify the signal light pulse into the second synchronous light pulse, so that the determined position information is more accurate.

Description

Signal light pulse position determining method, system, transmitting end and receiving end
Technical Field
The present disclosure relates to the field of quantum communications technologies, and in particular, to a method, a system, a transmitting end, and a receiving end for determining a signal light pulse position.
Background
Quantum Key Distribution (QKD) technology enables two parties in communication to generate and share a random, secure key for encrypting and decrypting information by transmitting quantum state optical pulse signals (i.e., signal optical pulses).
Referring to fig. 1, the key generation process is: a sending end Alice of the QKD system prepares a basic vector (expressed by two states of 0 and 1) of random signal light pulses, a receiving end Bob finishes random measurement by randomly selecting a measurement basic vector, and when the Bob end finishes the random measurement, a classical network interaction channel is used for informing the Alice end of which signal light pulse is detected by the Alice end, which basic vector is randomly selected, but key information obtained by specific measurement is secret; after receiving the information disclosed by the Bob end, the Alice end finds the corresponding random luminous information cached by the Alice end, determines whether the base vector used in transmission is consistent with the base vector randomly selected by the Bob end (opposite base), and then feeds back the confirmation information of the consistent quantum state base vectors to the Bob end, so that the Alice end and the Bob end can keep the Key information (Key) corresponding to the signal light pulse with the consistent base vector to form a shared Key (original Key).
Because the signal light pulse sent by Alice end is very weak, the number of signal light pulses reaching Bob end after being attenuated by the transmission channel is greatly reduced, and the single photon detector at Bob end is not efficient, so that the detection Key at Bob end can be very sparse, as shown in the corresponding row of 'Bob detection Key' in fig. 1. In order to realize the process of performing the base vector comparison of the signal light pulses detected by the Bob end and the Alice end, the Bob end needs to determine the corresponding relationship between the signal light pulses detected by the Bob end and the signal light pulses emitted by the Alice end.
In existing practical QKD systems, one common implementation is: the Alice end and the Bob end perform time synchronization through synchronous light pulses with lower transmission frequency (such as 100 KHz) and higher intensity, single photon level signal light pulses (with higher transmission frequency (such as tens of MHz-GHz) are uniformly distributed at equal intervals between adjacent synchronous light pulses except for head and tail silence areas, and the time sequence relationship between the two pulses is kept stable in the transmitting and receiving ends and the channel transmission process; the Bob end determines a coarse time coordinate by detecting a synchronous light pulse (for example, 100KHz corresponds to one synchronous light pulse every 10 us), determines specific time information of the signal light pulse according to a time difference between the detected signal light pulse and a previous synchronous light pulse, and further converts the specific time information into unique position information (namely, the number of the signal light pulse after the latest synchronous light pulse), so that the signal light pulse detected by the Bob end corresponds to the signal light pulse emitted by the Alice end one by one.
However, if the synchronization light pulse is too low in signal strength of a part of the synchronization light pulse due to the reason that the channel transmission attenuation is large (such as long-distance free space transmission in the atmosphere or long-distance optical fiber channel transmission), the Bob end detector cannot correctly identify (i.e. the synchronization light pulse is lost), so that the Bob end cannot obtain the accurate position information of the detected signal light pulse, and finally the basic vector comparison process is disturbed, and an accurate quantum key cannot be generated.
Disclosure of Invention
In view of this, the present application provides a method, a system, a transmitting end and a receiving end for determining the position of a signal light pulse, which are used for solving the problem that the prior art cannot obtain the accurate position information of the detected signal light pulse, and the technical scheme is as follows:
a signal light pulse position determining method is applied to a receiving end and comprises the following steps:
receiving first synchronous light pulses sent by a sending end, wherein the signal intensity of the first synchronous light pulses is first intensity, and the first intensity enables the receiving end to receive each first synchronous light pulse;
generating a notification message based on the first synchronous light pulse, and sending the notification message to a sending end, so that when the sending end receives the notification message and sends a set number of first synchronous light pulses, the sending end sends the signal light pulse and a second synchronous light pulse to a receiving end after combining, wherein the notification message is used for notifying the sending end that the first synchronous light pulse has been received, the signal intensity of the second synchronous light pulse is second intensity, and the second intensity is smaller than the first intensity;
Receiving the combined signal light pulse and the second synchronous light pulse from the transmitting end, splitting the received signal light pulse and the second synchronous light pulse and converting the split signal light pulse and the second synchronous light pulse into an electric signal form;
for each received second synchronous light pulse in the form of an electric signal, measuring the time difference between each signal light pulse under the second synchronous light pulse and the second synchronous light pulse, classifying each signal light pulse under the second synchronous light pulse into the second synchronous light pulse according to the measured time difference and the synchronous light time interval to obtain the position information of each signal light pulse under the second synchronous light pulse, wherein the synchronous light time interval is the inverse of the sending frequency of the second synchronous light pulse, the signal light pulse under a second synchronous light pulse refers to the signal light pulse in the form of the electric signal between the second synchronous light pulse and the received next second synchronous light pulse, and the second synchronous light pulse of one signal light pulse under a second synchronous light pulse is the second synchronous light pulse, or the second synchronous light pulse lost between the second synchronous light pulse and the received next second synchronous light pulse.
Optionally, measuring a time difference between each signal light pulse under the second synchronous light pulse and the second synchronous light pulse, includes:
taking the second synchronous light pulse as a starting signal of the precise time measuring chip, taking each signal light pulse under the second synchronous light pulse as a stopping signal of the precise time measuring chip, measuring the time difference between the starting signal and each stopping signal, and taking the time difference between each signal light pulse under the second synchronous light pulse and the second synchronous light pulse as the time difference between each signal light pulse under the second synchronous light pulse and the second synchronous light pulse.
Optionally, classifying each signal light pulse under the second synchronous light pulse into the second synchronous light pulse according to the measured time difference value and the synchronous light time interval to obtain the position information of each signal light pulse under the second synchronous light pulse, including:
for each signal light pulse under the second synchronization light pulse:
dividing the measured time difference value corresponding to the signal light pulse by the synchronous light time interval to obtain integer quotient and remainder corresponding to the signal light pulse;
classifying the signal light pulse into a second synchronous light pulse to which the signal light pulse belongs according to an integer quotient corresponding to the signal light pulse;
And calculating the position information of the signal light pulse under the second synchronous light pulse to which the signal light pulse belongs according to the remainder corresponding to the signal light pulse.
Optionally, the method further comprises:
and sequentially generating an integer quotient of first synchronous optical compensation pulses between the second synchronous optical pulse and the received next second synchronous optical pulse, wherein the first synchronous optical compensation pulses are used for time synchronization.
Optionally, the method further comprises:
when measuring the time difference value between each signal light pulse under the second synchronous light pulse and the second synchronous light pulse, if the time difference value between any signal light pulse under the second synchronous light pulse and the second synchronous light pulse is larger than the maximum range of the precise time measuring chip, timing by a timer, and generating a second synchronous light compensation pulse according to the timing time and the synchronous light time interval until the next second synchronous light pulse is received, wherein the timer is driven by a high-frequency clock, and the second synchronous light compensation pulse is used for time synchronization.
A signal light pulse position determining method is applied to a transmitting end and comprises the following steps:
generating an initial synchronization light pulse;
processing the initial synchronous light pulse into first synchronous light pulses, and sending the first synchronous light pulses to a receiving end, so that the receiving end generates and sends a notification message to the sending end based on the received first synchronous light pulses, wherein the signal strength of the first synchronous light pulses is first strength, the first strength enables the receiving end to receive each first synchronous light pulse, and the notification message is used for notifying the sending end that the first synchronous light pulses are received;
When the notification message is received and a set number of first synchronous light pulses are sent, processing the initial synchronous light pulses into second synchronous light pulses, wherein the signal intensity of the second synchronous light pulses is second intensity which is smaller than the first intensity;
generating signal light pulses, and sending the signal light pulses and the second synchronization light pulses to a receiving end after combining the signal light pulses and the second synchronization light pulses, so that the receiving end measures the time difference between each signal light pulse under the second synchronization light pulses and each second synchronization light pulse, classifies each signal light pulse under the second synchronization light pulses to the second synchronization light pulse according to the measured time difference and the synchronization light time interval to obtain position information of each signal light pulse under the second synchronization light pulse, wherein the synchronization light time interval is the inverse of the sending frequency of the second synchronization light pulse, the signal light pulse under one second synchronization light pulse refers to the signal light pulse in the form of an electrical signal between the second synchronization light pulse and the next received second synchronization light pulse, and the second synchronization light pulse under one second synchronization light pulse is the second synchronization light pulse, or the second synchronization light pulse between the second synchronization light pulse and the next received second synchronization light pulse is lost.
A signal light pulse position determining system comprises a transmitting end and a receiving end;
the transmitting end is used for generating initial synchronous light pulses, processing the initial synchronous light pulses into first synchronous light pulses and transmitting the first synchronous light pulses to the receiving end, wherein the signal intensity of the first synchronous light pulses is first intensity, and the receiving end can receive each first synchronous light pulse by the first intensity;
the receiving end is used for generating a notification message based on the first synchronous optical pulse and sending the notification message to the sending end, wherein the notification message is used for notifying the sending end that the first synchronous optical pulse is received;
the sending end is further used for processing the initial synchronous light pulse into a second synchronous light pulse when the notification message is received and a set number of first synchronous light pulses are sent, generating a signal light pulse, and sending the signal light pulse and the second synchronous light pulse to the receiving end after combining the signal light pulse and the second synchronous light pulse, wherein the signal intensity of the second synchronous light pulse is second intensity, and the second intensity is smaller than the first intensity;
the receiving end is further configured to divide and convert the received combined signal light pulse and the second synchronization light pulse into an electrical signal form, and, for each received second synchronization light pulse in the electrical signal form, measure a time difference between each signal light pulse under the second synchronization light pulse and the second synchronization light pulse, and classify each signal light pulse under the second synchronization light pulse to the second synchronization light pulse according to the measured time difference and the synchronization light time interval, so as to obtain position information of each signal light pulse under the second synchronization light pulse, where the synchronization light time interval is a reciprocal of a transmission frequency of the second synchronization light pulse, a signal light pulse under a second synchronization light pulse refers to a signal light pulse in the electrical signal form between the second synchronization light pulse and a received next second synchronization light pulse, and a signal light pulse under a second synchronization light pulse belongs to the second synchronization light pulse, or a second synchronization light pulse between the second synchronization light pulse and the received next second synchronization light pulse is lost.
A receiving end, comprising: the device comprises a demultiplexer, a synchronous optical detector, a signal optical detector, a precise time measurement chip and a data processor, wherein the data processor comprises a timer and a counter;
the demultiplexer is used for receiving the first synchronous optical pulse sent by the sending end and sending the first synchronous optical pulse to the synchronous optical detector, wherein the signal intensity of the first synchronous optical pulse is first intensity, and the first intensity enables the receiving end to receive each first synchronous optical pulse;
a synchronous light detector for converting the first synchronous light pulse into an electrical signal form;
the data processor is used for generating a notification message based on the first synchronous optical pulses in the form of electric signals and sending the notification message to the sending end, so that when the sending end receives the notification message and sends a set number of first synchronous optical pulses, the sending end sends the signal optical pulses and the second synchronous optical pulses to the demultiplexer after combining;
the demultiplexer is further configured to receive the combined signal light pulse and the second synchronous light pulse from the transmitting end, and split the received combined signal light pulse and the received second synchronous light pulse;
the synchronous optical detector is also used for converting the second synchronous optical pulse after beam splitting into an electric signal form;
The signal light detector is used for converting the split signal light pulse into an electric signal form;
the precise time measuring chip is used for measuring the time difference value between each signal light pulse under the second synchronous light pulse and the second synchronous light pulse for each received second synchronous light pulse in the form of an electric signal, wherein the signal light pulse under one second synchronous light pulse refers to the signal light pulse in the form of the electric signal between the second synchronous light pulse and the received next second synchronous light pulse;
the data processor is further configured to classify each signal light pulse under the second synchronization light pulse into the second synchronization light pulse according to the measured time difference value and the synchronization light time interval, so as to obtain position information of each signal light pulse under the second synchronization light pulse, where the synchronization light time interval is a reciprocal of a transmission frequency of the second synchronization light pulse, and a second synchronization light pulse to which a signal light pulse under a second synchronization light pulse belongs is the second synchronization light pulse, or a second synchronization light pulse lost between the second synchronization light pulse and a received next second synchronization light pulse.
Optionally, the precision time measurement chip is a wide-range TDC measurement chip, or a chip realized based on an FPGA carry chain clock interpolation method.
A transmitting end comprising: the synchronous controller, the synchronous optical laser, the signal optical laser, the synchronous optical adjustable attenuator and the wavelength division multiplexer;
the synchronous controller is used for triggering the synchronous optical laser to generate initial synchronous optical pulses, controlling the synchronous optical adjustable attenuator to process the initial synchronous optical pulses into first synchronous optical pulses, and outputting the first synchronous optical pulses to the receiving end through the wavelength division multiplexer so that the receiving end generates and sends notification messages to the synchronous controller based on the received first synchronous optical pulses, wherein the signal intensity of the first synchronous optical pulses is first intensity, the first intensity enables the receiving end to receive each first synchronous optical pulse, and the notification messages are used for notifying the sending end that the first synchronous optical pulses are received;
the synchronous controller is also used for controlling the synchronous light adjustable attenuator to process the initial synchronous light pulse into second synchronous light pulse and controlling the signal light laser to generate signal light pulse when receiving the notification message and transmitting the set number of first synchronous light pulses, controlling the wavelength division multiplexer to combine the second synchronous light pulse and the signal light pulse and transmit the combined signal light pulse and the second synchronous light pulse to the receiving end, so that the receiving end can measure the time difference value of each signal light pulse under the second synchronous light pulse and the second synchronous light pulse respectively for each received second synchronous light pulse, and classifying each signal light pulse under the second synchronous light pulse into the second synchronous light pulse according to the measured time difference value and the synchronous light time interval, the signal light pulse under the second synchronous light pulse refers to the signal light pulse in the form of an electric signal between the second synchronous light pulse and the received next second synchronous light pulse, and the second synchronous light pulse to which the signal light pulse under the second synchronous light pulse belongs is the second synchronous light pulse, or the second synchronous light pulse lost between the second synchronous light pulse and the received next second synchronous light pulse.
According to the technical scheme, the signal light pulse position determining method applied to the receiving end is characterized in that first synchronous light pulses sent by the sending end are received, notification messages are generated based on the first synchronous light pulses, the notification messages are sent to the sending end, so that when the notification messages are received and a set number of first synchronous light pulses are sent, the sending end sends the signal light pulses and the second synchronous light pulses to the receiving end after beam combination, then receives the signal light pulses and the second synchronous light pulses after beam combination from the sending end, splits and converts the received signal light pulses and the second synchronous light pulses into electrical signals, finally, for each received second synchronous light pulse in the form of electrical signals, the time difference between each signal light pulse under the second synchronous light pulse and the second synchronous light pulse is measured, and each signal light pulse under the second synchronous light pulse is classified to the second synchronous light pulse according to the measured time difference and the synchronous light time interval, so that position information of each signal light pulse under the second synchronous light pulse is obtained. Therefore, the synchronous light time interval is considered when the position information of the signal light pulse is determined, and the signal light pulse can be correctly classified into the second synchronous light pulse according to the measured time difference value corresponding to the signal light pulse and the synchronous light time interval, so that the position information of the signal light pulse under the second synchronous light pulse can be accurately determined even if the receiving end loses the second synchronous light pulse.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present application, and that other drawings may be obtained according to the provided drawings without inventive effort to a person skilled in the art.
FIG. 1 is a schematic diagram of a base vector alignment;
fig. 2 is a schematic flow chart of a method for determining a position of a signal light pulse according to an embodiment of the present application;
FIG. 3 is a timing diagram of a synchronization light pulse and a signal light pulse;
FIG. 4 is a schematic diagram of the arrival time of the light pulse of the signal measured by the precise time measuring chip;
fig. 5 is a schematic structural diagram of a receiving end provided in an embodiment of the present application;
fig. 6 is a schematic structural diagram of a transmitting end according to an embodiment of the present application.
Detailed Description
The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.
In view of the problems of the prior art, the present inventors have conducted intensive studies and finally have proposed a signal light pulse position determining method, and the signal light pulse position determining method provided in the present application will be described in detail by the following examples.
Referring to fig. 2, a flow chart of a signal light pulse position determining method provided in an embodiment of the present application is shown, where the signal light pulse position determining method may include:
step S201, the transmitting end generates an initial synchronization light pulse.
Here, the initial synchronization light pulse is a low frequency synchronization light pulse, for example, a 100KHz synchronization light pulse.
Step S202, the transmitting end processes the initial synchronous light pulse into a first synchronous light pulse and transmits the first synchronous light pulse to the receiving end.
The signal intensity of the first synchronous light pulse is a first intensity, and the first intensity enables the receiving end to receive each first synchronous light pulse.
Specifically, the transmitting end may process the initial synchronization optical pulse into a first synchronization optical pulse with higher signal strength at the synchronization start stage, and then transmit the first synchronization optical pulse to the receiving end through a classical network channel (optical fiber or free space). In this step, the transmitting end transmits a plurality of first synchronization light pulses, where the signal strength of the first synchronization light pulses is high enough, so that after the first synchronization light pulses are attenuated by the channel, it can still be ensured that each first synchronization light pulse is detected by the receiving end.
Step S203, the receiving end generates a notification message based on the first synchronous optical pulse, and sends the notification message to the sending end.
The notification message is used for notifying the transmitting end that the first synchronous light pulse is received.
Specifically, the first synchronization light pulse sent by the sending end is in an optical signal form, after the receiving end receives the first synchronization light pulse in the optical signal form, the first synchronization light pulse in the optical signal form is converted into an electric signal form, then a notification message is generated based on the first synchronization light pulse in the electric signal form, and the generated notification message is sent to the sending end, so that the sending end knows that the receiving end has received the first synchronization light pulse. Since the first synchronous optical pulse can be smoothly transmitted to the receiving end and the notification message can be smoothly transmitted to the transmitting end, both the transmitting end and the receiving end can determine that the channel is clear.
In step S204, when the transmitting end receives the notification message and the set number of first synchronization light pulses have been transmitted, the transmitting end processes the initial synchronization light pulses into second synchronization light pulses.
The signal intensity of the second synchronous light pulse is second intensity, and the second intensity is smaller than the first intensity.
In this step, as long as the transmitting end receives the notification message, the default receiving end receives each first synchronous light pulse transmitted by the transmitting end, and the timing sequences of the first synchronous light pulse and the second synchronous light pulse are synchronous. After the transmitting end confirms that the channel is unblocked and when a set number of first synchronous light pulses are transmitted, the transmitting end enters a formal key generation stage, and in order to reduce interference to signal light pulses, the transmitting end processes the initial synchronous light pulses into second synchronous light pulses.
Here, when the sending end receives the notification message and the set number of first synchronous light pulses are sent, the sending end processes the generated initial synchronous light pulses into second synchronous light pulses with lower signal strength, because the receiving end performs signal processing, generates feedback commands, feeds back the commands to the sending end through the classical network with a certain delay, and sends the set number of first synchronous light pulses to enable the receiving end to timely feed back the notification message to the sending end.
Optionally, the set number is 200K (200K first synchronous light pulses correspond to a delay time of 2 s), and of course, the set number may be other, which may be specifically determined according to practical situations, and this application is not limited thereto.
Step S205, the transmitting end generates a signal light pulse and transmits the signal light pulse and the second synchronous light pulse to the receiving end after the signal light pulse and the second synchronous light pulse are combined.
Here, the timing relationship between the second synchronization light pulses (corresponding to synchronization light pulses 1 to n in fig. 3) and the signal light pulses transmitted by the transmitting end can be seen from fig. 3.
Step S206, the receiving end receives the combined signal light pulse and the second synchronous light pulse from the sending end, splits the combined signal light pulse and the second synchronous light pulse and converts the split signal light pulse and the second synchronous light pulse into an electric signal form.
It should be noted that, the intensity of the second synchronization light pulse generated in step S204 is low, which may cause the second synchronization light pulse to be received by the receiving end due to channel attenuation when transmitted through the channel, that is, the number of the second synchronization light pulses received by the receiving end is less than or equal to the number of the second synchronization light pulses sent by the transmitting end.
In this step, when the receiving end receives the signal light pulse and the second synchronization light pulse after beam combination, the receiving end needs to split the signal light pulse and the second synchronization light pulse after beam combination to obtain the signal light pulse and the second synchronization light pulse after beam splitting.
The above-mentioned signal light pulse after beam splitting and the second synchronous light pulse after beam splitting are both in the form of optical signals, and because the precise time measurement chip adopted in the subsequent processing can only process the electric signals, the receiving end is required to convert the second synchronous light pulse in the form of optical signals into the form of electric signals, so as to obtain and convert the signal light pulse in the form of optical signals into the form of electric signals.
Step S207, the receiving end measures, for each received second synchronization light pulse in the form of each electrical signal, a time difference between each signal light pulse under the second synchronization light pulse and the second synchronization light pulse, and classifies each signal light pulse under the second synchronization light pulse to the second synchronization light pulse according to the measured time difference and the synchronization light time interval, so as to obtain position information of each signal light pulse under the second synchronization light pulse.
The synchronization light time interval refers to the inverse of the transmission frequency of the second synchronization light pulse, that is, the time interval between two adjacent second synchronization light pulses transmitted by the transmitting end, for example, if the second synchronization light pulse is 100KHz, the synchronization light time interval is 10us.
The signal light pulse under a second synchronous light pulse refers to the signal light pulse in the form of an electrical signal between the second synchronous light pulse and the next received second synchronous light pulse, that is, the second synchronous light pulse corresponding to the signal light pulse refers to the last received second synchronous light pulse before the signal light pulse; the second synchronous light pulse to which a signal light pulse under a second synchronous light pulse belongs is the second synchronous light pulse, or the second synchronous light pulse lost between the second synchronous light pulse and the next received second synchronous light pulse.
For example, referring to the schematic diagram of the arrival time of the signal light pulse measured by the precision time measurement chip shown in fig. 4, the signal light pulse under the second synchronous light pulse S0 received by the receiving end (Bob end) includes a signal light pulse i, a signal light pulse k and a signal light pulse x, and the signal light pulse under the second synchronous light pulse Sn-1 includes a signal light pulse y; the second synchronization light pulse to which the signal light pulse i under the second synchronization light pulse S0 belongs is S0, the second synchronization light pulse to which the signal light pulse k under the second synchronization light pulse S0 belongs is S0, the second synchronization light pulse to which the signal light pulse x under the second synchronization light pulse S0 belongs is S1 (the second synchronization light pulse S1 is a missing second synchronization light pulse, i.e., a second synchronization light pulse not detected by the receiving end), and the second synchronization light pulse to which the signal light pulse y under the second synchronization light pulse Sn-1 belongs is Sn-1.
In this embodiment, the detected signal light pulses are numbered by counting the second synchronization light pulses, for example, the signal light pulses 1 to m detected between the second synchronization light pulse Sn and the second synchronization light pulse sn+1 are numbered as the signal light pulses 1 to m under the second synchronization light pulse Sn, and the number can be used as the position information in this step.
It will be appreciated that if a certain second synchronization light pulse is lost, and then the detected signal light pulse is classified under the previous second synchronization light pulse by mistake, for example, if the second synchronization light pulse sn+1 is lost, the detected signal light pulse between the second synchronization light pulse sn+1 and the second synchronization light pulse sn+2 may be mistakenly numbered as the signal light pulse under the second synchronization light pulse Sn (for example, as shown in fig. 4, the second synchronization light pulse S1 is lost, resulting in that the signal light pulse x between the second synchronization light pulse S1 and the second synchronization light pulse S2 is mistakenly numbered as the signal light pulse x under the second synchronization light pulse S0), resulting in that the serial numbers of the signal light pulses detected by the receiving end are disordered from the beginning of the lost second synchronization light pulse, so that the one-to-one correspondence with the signal light pulse positions emitted by the transmitting end cannot be achieved, the subsequent base-vector ratio equivalent process cannot be completed, and thus the quantum key cannot be generated. This error can be avoided by the operation of this step.
Optionally, the receiving end of the step may measure, by means of a precision time measurement chip (the chip adopts a Start-Stop measurement mode, that is, a Start signal (Start) and a plurality of Stop signals (Stop), each Stop signal refers to a previous Start signal that is closest in time, the chip converts a time interval between the Start and the Stop into a digital signal, and outputs the digital signal through an interface pin), a time difference value between each signal light pulse under each second synchronous light pulse in the form of an electrical signal and a corresponding second synchronous light pulse, where the process specifically may include: taking the second synchronous light pulse as a starting signal of the precise time measuring chip, taking each signal light pulse under the second synchronous light pulse as a stopping signal of the precise time measuring chip, measuring the time difference between the starting signal and each stopping signal, and taking the time difference between each signal light pulse under the second synchronous light pulse and the second synchronous light pulse as the time difference between each signal light pulse under the second synchronous light pulse and the second synchronous light pulse.
Referring to fig. 4, the second synchronous optical pulse and the signal optical pulse sent by Alice end are included, and the second synchronous optical pulse and the signal optical pulse received by Bob end are included. In this example, the second synchronous optical pulse in the form of an electrical signal received by the receiving end may be accessed as a Start signal of the precision time measurement chip, and each signal optical pulse under the second synchronous optical pulse may be accessed as a Stop signal of the precision time measurement chip. Referring to fig. 4, if the second synchronization light pulse S1 is lost, the signal light pulse x is misclassified under the second synchronization light pulse S0, i.e., the signal light pulse x is the signal light pulse under the second synchronization light pulse S0, and the measured time difference is the time difference T1 between the signal light pulse x and the second synchronization light pulse S0; similarly, the measured time difference between the signal light pulse y under the second synchronous light pulse Sn-1 and the second synchronous light pulse Sn-1 is T2.
Alternatively, the precision time measurement chip may be a wide-range chip, for example, a wide-range TDC measurement chip, or a chip implemented based on an FPGA carry chain clock interpolation method, so as to measure a larger time difference, thereby enabling to generate a quantum key with a greater extent of detected signal light pulses.
Optionally, the process of classifying each signal light pulse under the second synchronization light pulse into the second synchronization light pulse according to the measured time difference value and the synchronization light time interval to obtain the position information of each signal light pulse under the second synchronization light pulse may include: and dividing the measured time difference value corresponding to the signal light pulse by the synchronous light time interval for each signal light pulse under the second synchronous light pulse to obtain integer quotient and remainder corresponding to the signal light pulse, classifying the signal light pulse into the second synchronous light pulse corresponding to the signal light pulse according to the integer quotient corresponding to the signal light pulse, and calculating the position information of the signal light pulse under the second synchronous light pulse corresponding to the signal light pulse according to the remainder corresponding to the signal light pulse. Here, the time difference corresponding to a signal light pulse under the second synchronous light pulse refers to the time difference between the signal light pulse and the second synchronous light pulse.
Specifically, it has been described above that the receiving end may have a case where the second synchronization light pulse is not received, that is, a case where the second synchronization light pulse is lost, for example, the second synchronization light pulse S1 shown in fig. 4 is lost. It should be understood that the time difference between the signal light pulse under a second synchronization light pulse and the second synchronization light pulse should be smaller than the synchronization light time interval, but when a certain second synchronization light pulse is lost, the signal light pulse under the second synchronization light pulse may be misclassified to the last second synchronization light pulse of the second synchronization light pulse, and then the time difference measured by the precision time measurement chip refers to the time difference between the signal light pulse under the second synchronization light pulse and the last second synchronization light pulse, where the time difference is necessarily larger than one synchronization light time interval and smaller than two synchronization light time intervals; similarly, if a plurality of second synchronization light pulses are continuously lost, the measured time difference will be greater than the plurality of synchronization light time intervals. Based on this, the integer quotient obtained by dividing the measured time difference corresponding to the signal light pulse by the synchronization light time interval is the number of the lost second synchronization light pulses between the second synchronization light pulse and the received next second synchronization light pulse, so that the signal light pulse can be correctly classified into the second synchronization light pulse to which the signal light pulse belongs according to the integer quotient, for example, in fig. 4, if the integer quotient obtained by dividing T1 by the synchronization light time interval is 1, it can be determined that one second synchronization light pulse is lost after the second synchronization light pulse S0 (i.e., S1), and then the second synchronization light pulse to which the signal light pulse x belongs is the second synchronization light pulse S1. And dividing the measured time difference value corresponding to the signal light pulse by the synchronous light time interval to obtain the remainder, namely the time difference value corresponding to the signal light pulse under the ideal condition (namely that the second synchronous light pulse is not lost). Since the time intervals between the signal light pulses are the same, the obtained remainder is divided by the time interval between the signal light pulses to obtain the position information of the signal light pulse under the second synchronous light pulse to which the signal light pulse belongs.
The position information obtained by the step is more accurate, so that the position information can be corresponding to the position information of the transmitting end.
In an alternative embodiment, in order to time synchronize the transmitting end and the receiving end, the present embodiment may further generate a synchronization optical compensation pulse when the second synchronization optical pulse is lost (several synchronization optical compensation pulses are generated when several second synchronization optical pulses are lost).
Optionally, the generating the synchronous light pulse in this embodiment includes, but is not limited to, the following two cases:
in the first case, for each second synchronization light pulse in the form of an electrical signal received by the receiving end, if the time difference between each signal light pulse under the second synchronization light pulse and the second synchronization light pulse is smaller than or equal to the maximum range of the precision time measurement chip (i.e., the second synchronization light pulse that is continuously lost does not exceed the range of the precision time measurement chip), the precision time measurement chip can measure the time difference corresponding to each signal light pulse under the second synchronization light pulse, and at this time, an integer quotient obtained by dividing the measured time difference by the synchronization light time interval can be sequentially generated between the second synchronization light pulse and the next received second synchronization light pulse, and then each signal light pulse under the second synchronization light pulse can be correctly classified into the second synchronization light pulse or the first synchronization light compensation pulse (after the first synchronization light compensation pulse is generated). Here, the first synchronization light compensation pulse is used for time synchronization of the transmitting end and the receiving end.
For example, referring still to fig. 4, if T1 is greater than 1 synchronization light time interval and less than 2 synchronization light time intervals, the integer quotient obtained is 1, and a first synchronization light compensation pulse is generated after the second synchronization light pulse S0, and the signal light pulse x is correctly classified under the generated first synchronization light compensation pulse; if T1 is greater than 2 and less than 3 synchronization light time intervals, the integer quotient obtained is 2, two first synchronization light compensation pulses are sequentially generated after the second synchronization light pulse S0, and the signal light pulse x is correctly classified under the generated second first synchronization light compensation pulse; similarly, as long as the continuously lost second synchronous light pulse does not exceed the measuring range of the precise time measuring chip, the signal light pulse detected by the receiving end can not be wrongly classified under other second synchronous light pulses, and the time synchronization of the transmitting end and the receiving end is ensured.
In the second case, for each second synchronization light pulse in the form of an electrical signal received by the receiving end, if the time difference between any signal light pulse under the second synchronization light pulse and the second synchronization light pulse is greater than the maximum range of the precision time measurement chip (i.e. the continuously lost second synchronization light pulse exceeds the range of the precision time measurement chip, for example, the maximum range of the precision time measurement chip is 100us, and 10 second synchronization light pulses are continuously lost, reaching the upper limit of the measurement range of 100 us), timing (rough timing) is performed by a timer, and a second synchronization light compensation pulse is generated according to the timing time and the synchronization light time interval, so as to continue to ensure time synchronization of the sending end and the receiving end until the next second synchronization light pulse is received, wherein the timer is driven by a high-frequency clock (for example, 100 MHz), and the second synchronization light compensation pulse is used for time synchronization of the sending end and the receiving end.
Here, generating the second synchronization light compensation pulse according to the counted time and the synchronization light time interval means generating one second synchronization light compensation pulse every synchronization light time interval according to the counted time, for example, the synchronization light time interval is 10us, and generating one second synchronization light compensation pulse every 10us time interval.
It should be noted that, in this embodiment, the continuously lost second synchronization light pulse exceeds the range of the precision time measurement chip, and if there is a signal light pulse arriving in this period, the signal light pulse arriving time cannot be measured accurately at this time, so the signal light pulse is directly discarded and does not participate in the key generation. When the second synchronous light pulse is recovered (e.g., sn-1 in FIG. 4), sn-1 is reused as a Start signal of the precise time measurement chip, and the newly detected signal light pulse (e.g., signal light pulse y in FIG. 4) is measured for a corresponding time difference T2 and output to a later stage to continue participating in key generation.
It should be noted that "first" and "second" of the first synchronous optical compensation pulse and the second synchronous optical compensation pulse are used only to distinguish the two cases, and in practical application, the first synchronous optical compensation pulse generated in the first case and the second synchronous optical compensation pulse generated in the second case may be the same.
According to the signal light pulse position determining method, a sending end generates and sends first synchronous light pulses to a receiving end, the receiving end generates notification messages based on the first synchronous light pulses and sends the notification messages to the sending end, when the sending end receives the notification messages and sends a set number of first synchronous light pulses, the sending end sends the generated signal light pulses and second synchronous light pulses to the receiving end after beam combination, the receiving end divides the received beam-combined signal light pulses and the received beam-combined signal light pulses into electric signal forms, for each received second synchronous light pulse in the electric signal form, the time difference value between each signal light pulse under the second synchronous light pulses and the second synchronous light pulses is measured, and according to the measured time difference value and the synchronous light time interval, each signal light pulse under the second synchronous light pulses is classified to the second synchronous light pulses to obtain position information of each signal light pulse under the second synchronous light pulses. Therefore, the synchronous light time interval is considered when the position information of the signal light pulse is determined, and the signal light pulse can be correctly classified into the second synchronous light pulse according to the measured time difference value corresponding to the signal light pulse and the synchronous light time interval, so that the position information of the signal light pulse under the second synchronous light pulse can be accurately determined even if the second synchronous light pulse is lost.
When the synchronization starts, the transmitting end transmits a first synchronous light pulse with stronger signal strength to ensure that the receiving end can detect the first synchronous light pulse, and when the key generation is prepared, a second synchronous light pulse with lower signal strength is transmitted, so that the interference on the signal light pulse can be reduced, and meanwhile, the time information of the signal light pulse is measured by combining with the precise time measuring chip, so that when the second synchronous light pulse is continuously lost, the position information of the signal light pulse can be accurately measured and the key generation can be participated; in addition, when the second synchronous light pulse is lost occasionally, the synchronous light compensation pulse can be automatically supplemented, so that the condition of timing error cannot occur at the receiving end, the detected signal light pulse can be correctly classified under the second synchronous light pulse, the time and data synchronization of the sending end and the receiving end are ensured, and the reliability of the system is improved.
The embodiment of the application also provides a signal light pulse position determining system, which comprises a transmitting end and a receiving end.
The transmitting end may be configured to generate an initial synchronization light pulse, process the initial synchronization light pulse into first synchronization light pulses, and transmit the first synchronization light pulses to the receiving end, where the signal strength of the first synchronization light pulses is a first strength, and the first strength enables the receiving end to receive each first synchronization light pulse.
The receiving end may be configured to generate a notification message based on the first synchronization light pulse, and send the notification message to the sending end, where the notification message is configured to notify the sending end that the first synchronization light pulse has been received.
The transmitting end may be further configured to process the initial synchronization light pulse into a second synchronization light pulse when the notification message is received and a set number of first synchronization light pulses have been transmitted, generate a signal light pulse, and transmit the signal light pulse and the second synchronization light pulse to the receiving end after combining the signal light pulse and the second synchronization light pulse, where the signal intensity of the second synchronization light pulse is a second intensity, and the second intensity is smaller than the first intensity.
The receiving end may be further configured to divide and convert the received combined signal light pulse and the second synchronization light pulse into an electrical signal form, and, for each received second synchronization light pulse in the electrical signal form, measure a time difference between each signal light pulse under the second synchronization light pulse and the second synchronization light pulse, and classify each signal light pulse under the second synchronization light pulse to the second synchronization light pulse according to the measured time difference and the synchronization light time interval, so as to obtain position information of each signal light pulse under the second synchronization light pulse, where the synchronization light time interval is a reciprocal of a transmission frequency of the second synchronization light pulse, and a signal light pulse under a second synchronization light pulse refers to a signal light pulse in the electrical signal form between the second synchronization light pulse and a received next second synchronization light pulse, and a signal light pulse under a second synchronization light pulse belongs to the second synchronization light pulse, or a second synchronization light pulse between the second synchronization light pulse and the received next second synchronization light pulse is lost.
It should be noted that, the signal light pulse position determining system provided in the embodiment of the present application and the signal light pulse position determining method described above may be referred to correspondingly, and detailed description of the signal light pulse position determining method may be referred to above, which is not repeated herein.
The embodiment of the application also provides a receiving end, and the receiving end provided by the embodiment of the application is described below. Referring to fig. 5, a schematic structural diagram of a receiving end provided in an embodiment of the present application is shown, and as shown in fig. 5, the receiving end may include: the device comprises a demultiplexer, a synchronous optical detector, a signal optical detector, a precise time measurement chip and a data processor, wherein the data processor comprises a timer and a counter, and has a function of time-position conversion, and the function of time-position conversion is to determine the position information of the signal optical pulse according to the time difference value corresponding to the signal optical pulse.
In this embodiment, the demultiplexer may be configured to receive the first synchronization optical pulse sent by the sending end, and send the first synchronization optical pulse to the synchronization optical detector, where the signal strength of the first synchronization optical pulse is a first strength, and the first strength enables the receiving end to receive each first synchronization optical pulse.
The synchronous light detector may be used to convert the first synchronous light pulse into an electrical signal form.
The data processor may be configured to generate a notification message based on the first synchronization light pulse in the form of an electrical signal, and send the notification message to the transmitting end, so that the transmitting end, when receiving the notification message and having sent a set number of the first synchronization light pulses, sends the signal light pulse and the second synchronization light pulse after being combined to the demultiplexer.
The demultiplexer may be further configured to receive the combined signal light pulse and the second synchronous light pulse from the transmitting end, and split the received combined signal light pulse and the second synchronous light pulse.
The synchronous light detector may also be used to convert the split second synchronous light pulse into an electrical signal.
The signal light detector may be used to convert the split signal light pulses into an electrical signal form.
The precision time measurement chip may be configured to measure, for each received second synchronization light pulse in the form of an electrical signal, a time difference between each signal light pulse in the second synchronization light pulse and the second synchronization light pulse, where a signal light pulse in a second synchronization light pulse refers to a signal light pulse in the form of an electrical signal between the second synchronization light pulse and a next received second synchronization light pulse.
The data processor may be further configured to classify each signal light pulse under the second synchronization light pulse into the second synchronization light pulse according to the measured time difference value and the synchronization light time interval, so as to obtain position information of each signal light pulse under the second synchronization light pulse, where the synchronization light time interval is a reciprocal of a transmission frequency of the second synchronization light pulse, and the second synchronization light pulse to which one signal light pulse under a second synchronization light pulse belongs is the second synchronization light pulse, or a second synchronization light pulse lost between the second synchronization light pulse and a received next second synchronization light pulse.
In an alternative embodiment, the precision time measurement chip may be a wide-range chip, i.e. the measurement range covers a plurality of second synchronization light time intervals (also referred to as second synchronization light periods), e.g. for a 100KHz second synchronization light pulse, the measurement range is N x 10us, N being a positive integer.
Alternatively, the precision time measurement chip may be a wide-range TDC measurement chip (for example, a TDC-GPX chip may implement a range of 40us or more in a G/R mode), or a chip implemented based on an FPGA carry chain clock interpolation method (which may implement a range of the order of hundred us under a certain measurement precision condition).
The embodiment of the application also provides a transmitting end, and the transmitting end provided by the embodiment of the application is described below. Referring to fig. 6, a schematic structural diagram of a transmitting end provided in an embodiment of the present application is shown, and as shown in fig. 6, the transmitting end may include: the device comprises a synchronous controller, a synchronous optical laser, a signal optical laser, a synchronous optical tunable attenuator and a wavelength division multiplexer.
In this embodiment, the synchronization controller may be configured to trigger the synchronization optical laser to generate an initial synchronization optical pulse, and control the synchronization optical tunable attenuator to process the initial synchronization optical pulse into first synchronization optical pulses, and output the first synchronization optical pulses to the receiving end via the wavelength division multiplexer, so that the receiving end generates and sends a notification message to the synchronization controller based on the received first synchronization optical pulses, where the signal strength of the first synchronization optical pulses is a first strength, and the first strength enables the receiving end to receive each first synchronization optical pulse, and the notification message is used to notify that the sending end has received the first synchronization optical pulses.
Specifically, for the transmitting end, when the QKD apparatus is started, the synchronization controller first adjusts the synchronization optical adjustable attenuator to reduce the attenuation by a set value (e.g., 6 dB), and then triggers the synchronization optical laser to generate a low-frequency initial synchronization optical pulse (e.g., an initial synchronization optical pulse of 100 KHz), and the initial synchronization optical pulse is processed into a first synchronization optical pulse after passing through the synchronization optical adjustable attenuator.
The synchronization controller may be further configured to, when a notification message is received and a set number of first synchronization light pulses have been transmitted, control the synchronization light adjustable attenuator to process an initial synchronization light pulse into a second synchronization light pulse and control the signal light laser to generate a signal light pulse, and control the wavelength division multiplexer to combine the second synchronization light pulse with the signal light pulse and transmit the combined signal light pulse and the second synchronization light pulse to the receiving end, so that the receiving end measures, for each second synchronization light pulse received, a time difference between each signal light pulse under the second synchronization light pulse and the second synchronization light pulse, respectively, and based on the measured time difference and the synchronization light time interval, classifying each signal light pulse under the second synchronous light pulse into the second synchronous light pulse to obtain the position information of each signal light pulse under the second synchronous light pulse, wherein the signal intensity of the second synchronous light pulse is the second intensity, the second intensity is smaller than the first intensity, the synchronous light time interval is the inverse of the sending frequency of the second synchronous light pulse, the signal light pulse under the second synchronous light pulse refers to the signal light pulse in the form of an electric signal between the second synchronous light pulse and the received next second synchronous light pulse, and the second synchronous light pulse to which the signal light pulse under the second synchronous light pulse belongs is the second synchronous light pulse, or the second synchronous light pulse lost between the second synchronous light pulse and the received next second synchronous light pulse.
Specifically, for the transmitting end, after receiving the notification message fed back by the receiving end, the synchronization controller adjusts the synchronization optical adjustable attenuator at a specific moment (for example, a set number of first synchronization optical pulses are sent, optionally, a set number is 200K), increases the attenuation by the set value (for example, 6 dB) to reduce the synchronization optical intensity, and reduces the possible interference to the signal optical pulses, at this time, the initial synchronization optical pulses generated by the synchronization optical laser are processed into second synchronization optical pulses after passing through the synchronization optical adjustable attenuator; after confirming that the attenuation is adjusted, the synchronous controller controls the signal light laser to start generating and transmitting the signal light pulse, and the signal light pulse and the second synchronous light pulse are transmitted to the receiving end after being combined.
It should be noted that, the transmitting end provided in the present application and the transmitting end in the above-described signal light pulse position determining method may be referred to correspondingly, the receiving end and the receiving end in the above-described signal light pulse position determining method may be referred to correspondingly, and detailed description may be referred to above, which is not repeated herein.
Finally, it is further noted that relational terms such as second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. The signal light pulse position determining method is characterized by being applied to a receiving end and comprising the following steps of:
receiving a first synchronous light pulse sent by a sending end, wherein the signal intensity of the first synchronous light pulse is a first intensity, and the first intensity enables the receiving end to receive each first synchronous light pulse;
generating a notification message based on the first synchronous light pulse, and sending the notification message to a sending end, so that when the sending end receives the notification message and sends a set number of first synchronous light pulses, the sending end sends a signal light pulse and a second synchronous light pulse to the receiving end after beam combination, wherein the notification message is used for notifying the sending end that the first synchronous light pulse has been received, the signal intensity of the second synchronous light pulse is second intensity, and the second intensity is smaller than the first intensity;
Receiving the signal light pulse and the second synchronous light pulse after beam combination from the transmitting end, splitting the received signal light pulse and the received second synchronous light pulse, and converting the split signal light pulse and the received second synchronous light pulse into an electric signal form;
for each received second synchronous light pulse in the form of an electric signal, measuring the time difference between each signal light pulse under the second synchronous light pulse and the second synchronous light pulse, classifying each signal light pulse under the second synchronous light pulse into the second synchronous light pulse according to the measured time difference and the synchronous light time interval to obtain the position information of each signal light pulse under the second synchronous light pulse, wherein the synchronous light time interval is the inverse of the sending frequency of the second synchronous light pulse, the signal light pulse under a second synchronous light pulse refers to the signal light pulse in the form of the electric signal between the second synchronous light pulse and the received next second synchronous light pulse, and the second synchronous light pulse to which the signal light pulse under a second synchronous light pulse belongs is the second synchronous light pulse, or the second synchronous light pulse lost between the second synchronous light pulse and the received next second synchronous light pulse.
2. The method according to claim 1, wherein measuring the time difference between each signal light pulse under the second synchronization light pulse and the second synchronization light pulse, respectively, comprises:
and taking the second synchronous light pulse as a starting signal of the precise time measurement chip, taking each signal light pulse under the second synchronous light pulse as a stop signal of the precise time measurement chip, and measuring the time difference value between the starting signal and each stop signal as the time difference value between each signal light pulse under the second synchronous light pulse and the second synchronous light pulse.
3. The method according to claim 2, wherein classifying each signal light pulse under the second synchronization light pulse into the second synchronization light pulse according to the measured time difference and the synchronization light time interval to obtain the position information of each signal light pulse under the second synchronization light pulse, comprises:
for each signal light pulse under the second synchronization light pulse:
dividing the measured time difference value corresponding to the signal light pulse by the synchronous light time interval to obtain integer quotient and remainder corresponding to the signal light pulse;
Classifying the signal light pulse into a second synchronous light pulse to which the signal light pulse belongs according to an integer quotient corresponding to the signal light pulse;
and calculating the position information of the signal light pulse under the second synchronous light pulse to which the signal light pulse belongs according to the remainder corresponding to the signal light pulse.
4. A signal light pulse position determination method according to claim 3, further comprising:
and sequentially generating the integral quotient of first synchronous light compensation pulses between the second synchronous light pulse and the received next second synchronous light pulse, wherein the first synchronous light compensation pulses are used for time synchronization.
5. The signal light pulse position determination method according to claim 2, further comprising:
when the time difference between each signal light pulse under the second synchronous light pulse and the second synchronous light pulse is measured, if the time difference between any signal light pulse under the second synchronous light pulse and the second synchronous light pulse is larger than the maximum range of the precision time measuring chip, the timing is performed through a timer, and a second synchronous light compensation pulse is generated according to the timing time and the synchronous light time interval until the next second synchronous light pulse is received, wherein the timer is driven through a high-frequency clock, and the second synchronous light compensation pulse is used for performing time synchronization.
6. The signal light pulse position determining method is characterized by being applied to a transmitting end and comprising the following steps of:
generating an initial synchronization light pulse;
processing the initial synchronous light pulse into first synchronous light pulses, and sending the first synchronous light pulses to a receiving end so that the receiving end generates and sends a notification message to the sending end based on the received first synchronous light pulses, wherein the signal strength of the first synchronous light pulses is first strength, the first strength enables the receiving end to receive each first synchronous light pulse, and the notification message is used for notifying the sending end that the first synchronous light pulses are received;
when the notification message is received and a set number of first synchronous light pulses are sent, processing the initial synchronous light pulses into second synchronous light pulses, wherein the signal intensity of the second synchronous light pulses is second intensity, and the second intensity is smaller than the first intensity;
generating signal light pulses, and sending the signal light pulses and the second synchronization light pulses to the receiving end after combining the signal light pulses and the second synchronization light pulses, so that the receiving end measures the time difference between each signal light pulse under the second synchronization light pulses and the second synchronization light pulse respectively, classifies each signal light pulse under the second synchronization light pulses into the second synchronization light pulse according to the measured time difference and the synchronization light time interval, so as to obtain the position information of each signal light pulse under the second synchronization light pulse, wherein the synchronization light time interval is the reciprocal of the sending frequency of the second synchronization light pulse, the signal light pulse under one second synchronization light pulse refers to the signal light pulse in the form of an electric signal between the second synchronization light pulse and the received next second synchronization light pulse, and the second synchronization light pulse under one second synchronization light pulse is the second synchronization light pulse, or the second synchronization light pulse between the second synchronization light pulse and the received next synchronization light pulse is lost.
7. The signal light pulse position determining system is characterized by comprising a transmitting end and a receiving end;
the transmitting end is used for generating an initial synchronous light pulse, processing the initial synchronous light pulse into first synchronous light pulses and transmitting the first synchronous light pulses to the receiving end, wherein the signal intensity of the first synchronous light pulses is first intensity, and the first intensity enables the receiving end to receive each first synchronous light pulse;
the receiving end is configured to generate a notification message based on the first synchronous optical pulse, and send the notification message to the sending end, where the notification message is used to notify the sending end that the first synchronous optical pulse has been received;
the sending end is further configured to process the initial synchronization light pulse into a second synchronization light pulse when the notification message is received and a set number of first synchronization light pulses are sent, generate a signal light pulse, and send the signal light pulse and the second synchronization light pulse to the receiving end after the signal light pulse and the second synchronization light pulse are combined, where the signal intensity of the second synchronization light pulse is a second intensity, and the second intensity is smaller than the first intensity;
The receiving end is further configured to split and convert the received combined signal light pulse and the second synchronization light pulse into an electrical signal form, and, for each received second synchronization light pulse in the electrical signal form, measure a time difference between each signal light pulse under the second synchronization light pulse and the second synchronization light pulse, and classify each signal light pulse under the second synchronization light pulse to the second synchronization light pulse according to the measured time difference and a synchronization light time interval, so as to obtain position information of each signal light pulse under the second synchronization light pulse, where the synchronization light time interval is a reciprocal of a transmission frequency of the second synchronization light pulse, a signal light pulse under a second synchronization light pulse refers to a signal light pulse in the electrical signal form between the second synchronization light pulse and a received next second synchronization light pulse, and a signal light pulse under a second synchronization light pulse is the second synchronization light pulse, or a signal light pulse under a second synchronization light pulse is received between the second synchronization light pulse and the second synchronization light pulse.
8. A receiving terminal, comprising: the device comprises a demultiplexer, a synchronous optical detector, a signal optical detector, a precise time measurement chip and a data processor, wherein the data processor comprises a timer and a counter;
the demultiplexer is configured to receive a first synchronous optical pulse sent by a sending end, and send the first synchronous optical pulse to the synchronous optical detector, where the signal strength of the first synchronous optical pulse is a first strength, and the first strength enables the receiving end to receive each first synchronous optical pulse;
the synchronous light detector is used for converting the first synchronous light pulse into an electric signal form;
the data processor is used for generating a notification message based on the first synchronous optical pulse in the form of an electric signal and sending the notification message to the sending end, so that when the notification message is received by the sending end and a set number of first synchronous optical pulses are sent, the signal optical pulse and the second synchronous optical pulse are combined and then sent to the demultiplexer;
the demultiplexer is further configured to receive the signal light pulse and the second synchronous light pulse after beam combination from the transmitting end, and split the received signal light pulse and the received second synchronous light pulse after beam combination;
The synchronous light detector is also used for converting the second synchronous light pulse after beam splitting into an electric signal form;
the signal light detector is used for converting the signal light pulse after beam splitting into an electric signal form;
the precision time measurement chip is configured to measure, for each received second synchronization light pulse in the form of an electrical signal, a time difference between each signal light pulse under the second synchronization light pulse and the second synchronization light pulse, where the signal light pulse under a second synchronization light pulse refers to a signal light pulse in the form of an electrical signal between the second synchronization light pulse and a next received second synchronization light pulse;
the data processor is further configured to classify each signal light pulse under the second synchronization light pulse into the second synchronization light pulse according to the measured time difference value and the synchronization light time interval, so as to obtain position information of each signal light pulse under the second synchronization light pulse, where the synchronization light time interval is a reciprocal of a transmission frequency of the second synchronization light pulse, and the second synchronization light pulse to which one signal light pulse under the second synchronization light pulse belongs is the second synchronization light pulse, or a second synchronization light pulse lost between the second synchronization light pulse and the received next second synchronization light pulse.
9. The receiver of claim 8, wherein the precision time measurement chip is a wide range TDC measurement chip or a chip implemented based on FPGA carry chain clock interpolation.
10. A transmitting terminal, comprising: the synchronous controller, the synchronous optical laser, the signal optical laser, the synchronous optical adjustable attenuator and the wavelength division multiplexer;
the synchronous controller is configured to trigger the synchronous optical laser to generate an initial synchronous optical pulse, control the synchronous optical adjustable attenuator to process the initial synchronous optical pulse into first synchronous optical pulses, and output the first synchronous optical pulses to the receiving end via the wavelength division multiplexer, so that the receiving end generates and sends a notification message to the synchronous controller based on the received first synchronous optical pulses, where the signal strength of the first synchronous optical pulses is a first strength, and the first strength enables the receiving end to receive each first synchronous optical pulse, and the notification message is used to notify the sending end that the first synchronous optical pulses have been received;
the synchronization controller is further configured to, when the notification message is received and a set number of the first synchronization light pulses have been transmitted, control the synchronization light adjustable attenuator to process the initial synchronization light pulse into a second synchronization light pulse and control the signal light laser to generate a signal light pulse, and control the wavelength division multiplexer to combine the second synchronization light pulse with the signal light pulse and transmit the combined signal light pulse and the second synchronization light pulse to the receiving end, so that the receiving end measures, for each of the second synchronization light pulses received, a time difference between each of the signal light pulses under the second synchronization light pulse and the second synchronization light pulse, respectively, and based on the measured time difference and synchronization light time interval, classifying each signal light pulse under the second synchronous light pulse into the second synchronous light pulse to obtain the position information of each signal light pulse under the second synchronous light pulse, wherein the signal intensity of the second synchronous light pulse is second intensity, the second intensity is smaller than the first intensity, the synchronous light time interval is the inverse of the sending frequency of the second synchronous light pulse, the signal light pulse under a second synchronous light pulse is the signal light pulse in the form of an electric signal between the second synchronous light pulse and the received next second synchronous light pulse, and the second synchronous light pulse under a second synchronous light pulse is the second synchronous light pulse or the second synchronous light pulse lost between the second synchronous light pulse and the received next second synchronous light pulse.
CN202111674739.7A 2021-12-31 2021-12-31 Signal light pulse position determining method, system, transmitting end and receiving end Pending CN116418408A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202111674739.7A CN116418408A (en) 2021-12-31 2021-12-31 Signal light pulse position determining method, system, transmitting end and receiving end

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202111674739.7A CN116418408A (en) 2021-12-31 2021-12-31 Signal light pulse position determining method, system, transmitting end and receiving end

Publications (1)

Publication Number Publication Date
CN116418408A true CN116418408A (en) 2023-07-11

Family

ID=87050057

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202111674739.7A Pending CN116418408A (en) 2021-12-31 2021-12-31 Signal light pulse position determining method, system, transmitting end and receiving end

Country Status (1)

Country Link
CN (1) CN116418408A (en)

Similar Documents

Publication Publication Date Title
CN107947926B (en) Synchronization method and device of quantum key distribution system
CN108737082B (en) Signal receiving device and receiving method
CN100568726C (en) A kind of based on the real random code generator of chaotic laser light and the method for generation random code thereof
CN113541819B (en) Time synchronization system for quantum key distribution
CN111740829A (en) Synchronization method and device of quantum key distribution system
CN108737089B (en) Single photon level detection system, method and device for quantum communication system transmitting end
CN113708846B (en) Gate control device for single-photon detector and quantum communication equipment
CN113708847B (en) Gate control device for single-photon detector and quantum communication equipment
US20140010556A1 (en) Optical line terminal
JP2007028215A (en) Station-side optical communication device
CN106789034B (en) Continuous variable quantum key distribution system data synchronization method based on local oscillator light
Bonk et al. Demonstration of ONU activation for in-service TDM-PON allowing uninterrupted low-latency transport links
CN106100837B (en) Synchronization device and method of full-duplex quantum key distribution system based on same wavelength
CN110351074B (en) Synchronous correction method and controller for quantum key distribution system
CN116418408A (en) Signal light pulse position determining method, system, transmitting end and receiving end
EP3503461A1 (en) Qkd synchronization apparatus and method
JP2005151597A (en) Quality monitor for optical signal
US20120128372A1 (en) Optical line termination, pon system, and data reception processing method
WO2020079776A1 (en) Distance measurement device and distance measurement method
CN110519057B (en) Classical signal coding and decoding method, synchronization method and device for quantum key distribution system
CN104125058A (en) Device and method for automatically calibrating synchronous light in quantum secret key distribution system
US11516563B2 (en) Passive optical network (PON) synchronization and clock recovery
EP4315735A1 (en) A system and method for time synchronisation
CN113132093B (en) Quantum key distribution method and node
US20210389432A1 (en) Distance-measurement apparatus and distance-measurement method

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination