A common fiber quantum key distribution system, method and passive optical network

Abstract

The present invention relates to the field of quantum information technology, and in particular to a common fiber quantum key distribution system, method and passive optical network. The common fiber quantum key distribution system of the present invention adds an ingeniously designed optical custom switch to the optical distribution network (ODN) part of the passive optical network, and cooperates with the combined use of a wavelength division multiplexer, and according to the rules of time division multiplexing, automatically switches the quantum signal line to the connection with the currently emitting optical network unit, so that the quantum signal is transmitted through the optical custom switch, thereby, the quantum signal transmission does not pass through the optical splitter, thereby avoiding the optical splitting loss of the quantum signal by the optical splitter.

Description

Technical Field

[0001] The present invention relates to the field of quantum information technology, and in particular to a common-fiber quantum key distribution system, method and passive optical network. Background Art

[0002] In the existing technology, the authorized utility model patent CN207706187U-Wavelength division multiplexing quantum cryptography communication device based on passive optical network (PON) adds a notch filter in front of the optical network unit (ONU) device to filter out the classical signal with the same wavelength as the quantum signal, and then transmits the classical signal with different wavelengths with the quantum signal on the same fiber, thereby reducing the impact of the in-band classical noise generated by the ONU device on the QKD system;

[0003] The authorized utility model patent CN208015742U-Quantum key distribution system and PON equipment co-fiber transmission system, by adding an adaptive optical attenuation / amplification device in front of the optical line terminal (OLT) and ONU, can reduce the impact of classical signals on quantum key distribution (QKD) and ensure the normal operation of the passive optical network.

[0004] The above two patents for implementing co-fiber QKD in passive optical networks mainly solve the problem of the impact of classical noise on the signal-to-noise ratio of the QKD system. Moreover, the above two patents have a common disadvantage that quantum signals will inevitably suffer losses when passing through the passive optical splitter in the optical distribution network (ODN). For a 1:n splitter, each quantum signal has only a 1 / n probability of passing through the optical splitter to reach the quantum key distribution receiving end, which will seriously reduce the transmission efficiency of the QKD quantum signal, that is, seriously reduce the signal-to-noise ratio of the QKD system, affecting the security key rate and maximum security transmission distance of the QKD system in the passive optical network. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the problem of light splitting loss of quantum signals by the optical splitter in the prior art.

[0006] In order to solve the above technical problems, the present invention provides a common fiber quantum key distribution system, which is arranged in a passive optical network, wherein the passive optical network includes an optical line terminal, an optical distribution network and a plurality of optical network units, and the common fiber quantum key distribution system includes:

[0007] A first quantum key distribution unit, deployed in the optical line terminal;

[0008] A second quantum key distribution unit, including a plurality of second quantum key distribution sub-units, which are correspondingly deployed in the plurality of optical network units;

[0009] An optical splitter, deployed in the optical distribution network;

[0010] an optical custom switch, deployed in the optical distribution network; and

[0011] A wavelength division multiplexing interface, deployed on the optical line terminal, the optical distribution network and the plurality of optical network units, to support co-fiber communication between the optical line terminal and the optical distribution network, and between the optical distribution network and the plurality of optical network units;

[0012] When any optical network unit sends a classical signal of the first band at the working moment, the corresponding second quantum key distribution subunit is triggered to send a quantum signal of the second band, and the classical signal and the quantum signal are combined and divided through the wavelength division multiplexing interface to reach the optical distribution network, and the optical customized switch opens the channel corresponding to the currently working optical network unit, so that the quantum signal passes through the optical customized switch, and

[0013] The quantum key is shared between the optical line terminal and the optical network unit by reaching the first quantum key distribution unit or pairing with the quantum signal sent by the first quantum key distribution unit.

[0014] Preferably, the optical custom switch comprises:

[0015] A switching control module is used to detect the currently working optical network unit and output a control signal;

[0016] A connection module is connected to the switching control module and is used to switch the quantum signal line to be connected to the currently working optical network unit detected by the switching control module according to the control signal.

[0017] Preferably, the switching control module includes:

[0018] A plurality of optical splitters, connected to the plurality of optical network units via wavelength division multiplexing interfaces, for separating a portion of the light intensity from the classical signal according to a preset ratio, and sending the remaining classical signal to the optical splitter;

[0019] A multi-channel photoelectric detector, wherein a plurality of input channels are respectively connected to the plurality of optical splitters correspondingly, is used to detect the currently working optical network unit according to the light intensity.

[0020] Preferably, the co-fiber quantum key distribution system is based on a preparation-measurement protocol, that is, the second quantum key distribution unit is a quantum key distribution transmitting end, and the first quantum key distribution unit is a quantum key distribution receiving end.

[0021] Preferably, the common-fiber quantum key distribution system is based on a quantum relay-type quantum key distribution protocol, that is, the first quantum key distribution unit and the second quantum key distribution unit are both quantum key distribution transmitting ends, and a quantum measurement device is deployed between the output end of the optical customized switch and the wavelength division multiplexing interface.

[0022] Preferably, the common-fiber quantum key distribution system is based on a quantum relay-type quantum key distribution protocol, the first quantum key distribution unit and the second quantum key distribution unit are both quantum key distribution transmitting ends, and a quantum measurement device is deployed between the first quantum key distribution unit and the wavelength division multiplexing interface.

[0023] Preferably, the isolation of the wavelength division multiplexing interface is not less than 60dB.

[0024] The present invention also provides a passive optical network, comprising:

[0025] The optical line terminal side includes an optical line terminal, a first quantum key distribution unit and a wavelength division multiplexing interface;

[0026] The optical network unit side includes several optical network units, and a second quantum key distribution subunit and a wavelength division multiplexing interface configured corresponding to each optical network unit;

[0027] An optical distribution network, including an optical splitter, an optical custom switch, and wavelength division multiplexing interfaces respectively arranged towards an optical line terminal side and an optical network unit side;

[0028] When any optical network unit sends a classical signal of the first band at the working moment, the corresponding second quantum key distribution subunit is triggered to send a quantum signal of the second band, and the classical signal and the quantum signal are combined and divided through the wavelength division multiplexing interface to reach the optical distribution network, and the optical customized switch opens the channel corresponding to the currently working optical network unit, so that the quantum signal passes through the optical customized switch, and

[0029] The quantum key is shared between the optical line terminal and the optical network unit by reaching the first quantum key distribution unit or pairing with the quantum signal sent by the first quantum key distribution unit.

[0030] The present invention also provides a common fiber quantum key distribution method, comprising:

[0031] When the second quantum key distribution subunit in the above-mentioned common fiber quantum key distribution system is triggered by the classical signal of the first band sent by the corresponding optical network unit at the working time, a quantum signal of the second band is sent;

[0032] When the classical signal and the quantum signal are combined and split through the wavelength division multiplexing interface and reach the optical distribution network, the channel corresponding to the currently working optical network unit is opened by using the optical custom switch, so that the quantum signal passes through the optical custom switch, and

[0033] The quantum key is shared between the optical line terminal and the optical network unit by reaching the first quantum key distribution unit or pairing with the quantum signal sent by the first quantum key distribution unit.

[0034] Preferably, the step of using the optical customized switch to open the channel corresponding to the currently working optical network unit so that the quantum signal passes through the optical customized switch comprises:

[0035] The switching control module is used to detect the currently working optical network unit, and the connection module is controlled to switch the quantum signal line to connect with the detected currently working optical network unit.

[0036] The present invention also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the above-mentioned common-fiber quantum key distribution method for a passive optical network are implemented.

[0037] The above technical solution of the present invention has the following advantages compared with the prior art:

[0038] The co-fiber quantum key distribution (QKD) system described in the present invention adds an ingeniously designed optical custom switch to the optical distribution network (ODN) part of the passive optical network, and uses it in combination with a wavelength division multiplexer. According to the rules of time division multiplexing, the quantum signal line is automatically switched to connect with the currently luminous optical network unit, so that the quantum signal is transmitted through the optical custom switch. As a result, the quantum signal transmission does not pass through the optical splitter, thereby avoiding the optical splitting loss of the quantum signal by the optical splitter. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0040] Figure 1 It is a structural diagram of a common fiber quantum key distribution system of the present invention;

[0041] Figure 2 It is a structural diagram of the common fiber quantum key distribution system based on the preparation-measurement protocol of the present invention;

[0042] Figure 3 It is a schematic diagram of partial deployment of an optical distribution network provided by a first embodiment of the present invention;

[0043] Figure 4 is a schematic diagram of partial deployment of an optical distribution network provided by a second embodiment of the present invention;

[0044] Figure 5 It is a structural diagram of the first common fiber quantum key distribution system based on quantum relay protocol of the present invention;

[0045] Figure 6 This is a structural diagram of the second common-fiber quantum key distribution system based on the quantum relay protocol of the present invention. DETAILED DESCRIPTION

[0046] The core of the present invention is to provide a common-fiber quantum key distribution system, method and computer storage medium, which avoids the optical splitting loss of quantum signals caused by optical splitters.

[0047] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0048] As the mainstream technology for fixed network access, passive optical network is mainly used for operator home / commercial user access, and is gradually expanding to large enterprise campuses (POL) and even to industry networks (F5G), with a promising development prospect. There are many subdivided types of passive optical network technology, but their foundations are the same. The passive optical network architecture has the following characteristics:

[0049] (1) PON is a point-to-multipoint passive optical network consisting of an optical line terminal (OLT), an optical network unit (ONU), and an optical distribution network (ODN). The word "passive" refers to the passive part of the ODN.

[0050] (2) PON can use either primary or secondary splitting, and the access radius (the distance between OLT and ONU) is generally within 20 kilometers;

[0051] (3) The wavelengths used for downlink and downlink communications in passive optical networks are different. For common EPON and GPON, the downlink wavelength is 1490nm and the uplink wavelength is 1310nm. The two-way communications do not affect each other and are two-way full-duplex communications.

[0052] (4) Due to the characteristics of passive splitters, the passive optical network uses broadcasting to transmit data downstream. For downstream data, each ONU actively filters its own data (for example, by ID), and the data sent by the OLT to each ONU is encrypted by the symmetric key shared with the ONU, so that the ONU can receive its own data while ensuring the confidentiality of the data;

[0053] (5) Since the wavelength of the upstream optical signal of each ONU is the same, the upstream communication is carried out in a time division multiplexing manner. The ONU emits light, that is, sends data, in its own time slot according to the time slot allocated by the OLT.

[0054] Please refer to Figure 1 , Figure 1 This is a structural diagram of a common fiber quantum key distribution system of the present invention, wherein the common fiber quantum key distribution system is arranged in a passive optical network, wherein the passive optical network includes an optical line terminal, an optical distribution network and several optical network units, wherein the optical line terminal OLT transmits a downlink classical signal wavelength of 1490nm; the optical network unit ONU transmits an uplink classical signal wavelength of 1310nm;

[0055] The co-fiber quantum key distribution system comprises:

[0056] A first quantum key distribution unit 1, deployed in the optical line terminal 2;

[0057] The second quantum key distribution unit 3 includes several second quantum key distribution sub-units, which are correspondingly deployed on the several optical network units 4; the QKD unit is a quantum key distribution terminal (which can be a receiving end or a transmitting end), and the wavelength of the emitted quantum signal is in the C band, such as 1550nm; the OLT / ONU and the QKD are connected by electrical signals, such as network cables, for classical communication of management signals.

[0058] The optical splitter BS 5 is deployed in the optical distribution network, and the splitting ratio is adjustable according to specific needs, which is assumed to be 1:n here;

[0059] An optical custom switch OS 6, deployed in the optical distribution network; and

[0060] The wavelength division multiplexing interface FWDM 7 deployed on the optical line terminal, the wavelength division multiplexing interface 8 deployed on the optical distribution network and the wavelength division multiplexing interface 9 deployed on the plurality of optical network units are used to support the fiber-to-fiber communication between the optical line terminal and the optical distribution network, and between the optical distribution network and the plurality of optical network units. FWDM is a commonly used wavelength division multiplexer that can combine and split light in the O-band and C-band. In order to reduce the influence of classical noise on the signal-to-noise ratio of the QKD system, it is recommended that the isolation of FWDM be no less than 60 dB.

[0061] In the upstream direction:

[0062] When any optical network unit sends a classical signal of the first band at the working moment, the corresponding second quantum key distribution subunit is triggered to send a quantum signal of the second band, and the classical signal and the quantum signal are combined and divided through the wavelength division multiplexing interface to reach the optical distribution network, and the optical customized switch opens the channel corresponding to the currently working optical network unit, so that the quantum signal passes through the optical customized switch, and

[0063] The quantum key is shared between the optical line terminal and the optical network unit by reaching the first quantum key distribution unit or pairing with the quantum signal sent by the first quantum key distribution unit.

[0064] In the downlink direction:

[0065] The classical signal transmitted by OLT and the quantum signal transmitted by QKD are combined and split through the wavelength division multiplexer interface deployed on the optical line terminal side, and then multiplexed into one optical fiber for transmission, i.e., co-fiber transmission. After reaching the optical splitter, they are broadcast to each optical network unit.

[0066] Please refer to Figure 2 , Figure 2 This is a structural diagram of the common-fiber quantum key distribution system based on the preparation-measurement protocol (such as the BB84 protocol) of the present invention, wherein the second quantum key distribution unit is a quantum key distribution transmitter (QKD-T) and the first quantum key distribution unit is a quantum key distribution receiver (QKD-R).

[0067] The co-fiber quantum key distribution system described in the present invention adds an ingeniously designed optical custom switch to the optical distribution network (ODN) part of the passive optical network, and uses it in combination with a wavelength division multiplexer. According to the rules of time division multiplexing, the quantum signal line is automatically switched to connect with the currently luminous optical network unit, so that the quantum signal is transmitted through the optical custom switch. As a result, the quantum signal transmission does not pass through the optical splitter, thereby avoiding the optical splitting loss of the quantum signal by the optical splitter.

[0068] Based on the above embodiments, this embodiment further describes the optical custom switch:

[0069] like Figure 3 , the optical customized switch deployed on the optical distribution network side includes:

[0070] The switching control module 10 is used to detect the currently working optical network unit and output a control signal;

[0071] The connection module 11 is connected to the switching control module and is used to switch the quantum signal line to be connected to the currently working optical network unit detected by the switching control module according to the control signal.

[0072] like Figure 4 , the switching control module includes:

[0073] Multiple Splitter BS 1 ,BS 2 ...BS n 12 (there is no fixed requirement for the splitting ratio, which can be set to 50:50, 90:10, etc. It is recommended that the light intensity distributed to the optical custom switch OS is not greater than the light intensity distributed to the optical splitter BS, because the light intensity distributed to the OS is used to detect which ONU is emitting light and cannot affect normal uplink communication), connected to the plurality of optical network units through the wavelength division multiplexing interface, and used to separate a part of the light intensity from the classical signal according to a preset ratio, and send the remaining classical signal to the optical splitter;

[0074] The multi-channel photoelectric detector 13, whose multiple input channels are respectively connected to the multiple optical splitters, is used to detect the currently working optical network unit according to the light intensity.

[0075] The uplink classical signal transmitted by ONU passes through BS n After light splitting, the time of reaching the switching control module is different and meets the time division multiplexing rules. The switching control module infers which ONU is emitting light according to the order of the photodetector PD response signal time (or according to which input port causes the PD response), thereby determining which ONU is connected to the QKD on the OLT side, and realizing the switching and connection of the quantum line through the connection module. For example, assuming that light is emitted from ONU1 to ONUn in sequence, then the uplink signal of ONU1 reaches the switching control module first, and the input port corresponding to the signal causes the detector PD to respond first. At this time, the switching control module controls the connection module to realize the connection of the QKD on the OLT side with the QKD1 corresponding to ONU1, completing the quantum key distribution. The generated quantum key is shared by OLT and ONU1, and is used for the subsequent encryption and decryption transmission of uplink and downlink classical signals. And so on, until the QKD on the OLT side is connected to the QKDn corresponding to ONUn through the optical switch to realize quantum key distribution.

[0076] The ODN part of this solution can be packaged independently as an ODN device for quantum encryption passive optical network.

[0077] The co-fiber quantum key distribution system provided by the present invention is also applicable to a quasi-quantum relay quantum key distribution protocol (such as a measurement device-independent MDI-quantum key distribution protocol and a dual-field TF-quantum key distribution protocol). The quantum signal from the quantum key distribution transmitter on the OLT side and the quantum signal from the quantum key distribution transmitter on the ONU side complete the quantum signal measurement in the quantum measurement device, such as Figure 5 As shown, the first quantum key distribution unit and the second quantum key distribution unit are both quantum key distribution transmitting ends, and a quantum measurement device 14 is deployed between the first quantum key distribution unit and the wavelength division multiplexing interface.

[0078] like Figure 6 As shown, the first quantum key distribution unit and the second quantum key distribution unit are both quantum key distribution transmitters (QKD-T), and a quantum measurement device 14 is deployed between the output end of the optical custom switch and the wavelength division multiplexing interface.

[0079] The present invention also provides a common fiber quantum key distribution method for a passive optical network, comprising:

[0080] In the downstream direction: the classical signal from the OLT is combined and split with the quantum signal through the wavelength division multiplexing interface, and then enters the optical splitter of the ODN part, and reaches the ONU through broadcasting to carry out normal passive optical network communication;

[0081] In the upstream direction:

[0082] When the second quantum key distribution subunit in the above-mentioned common fiber quantum key distribution system is triggered by the classical signal of the first band sent by the corresponding optical network unit at the working time, a quantum signal of the second band is sent;

[0083] When the classical signal and the quantum signal are combined and split through the wavelength division multiplexing interface and reach the optical distribution network, the optical customized switch switching control module is used to detect the currently working optical network unit, and the connection module is controlled to switch the quantum signal line to connect with the currently working optical network unit detected, so that the quantum signal passes through the optical customized switch, and

[0084] The quantum key is shared between the optical line terminal and the optical network unit by reaching the first quantum key distribution unit or pairing with the quantum signal sent by the first quantum key distribution unit.

[0085] The present invention utilizes FWDM to realize the combination and demultiplexing of classical signals and quantum signals in a passive optical network, and performs multi-stage combination and demultiplexing. It utilizes an optical splitter BS, an optical customized switch and FWDM to avoid the serious loss of quantum signals by the optical splitter of the original network. It utilizes the time division multiplexing mode of the ONU, the optical splitter and the optical switch to realize the switching and differentiation of different quantum lines.

[0086] The present invention also provides a passive optical network, characterized in that it comprises:

[0087] The optical line terminal side includes an optical line terminal, a first quantum key distribution unit and a wavelength division multiplexing interface;

[0088] The optical network unit side includes several optical network units, and a second quantum key distribution subunit and a wavelength division multiplexing interface configured corresponding to each optical network unit;

[0089] An optical distribution network, including an optical splitter, an optical custom switch, and wavelength division multiplexing interfaces respectively arranged towards an optical line terminal side and an optical network unit side;

[0090] When any optical network unit sends a classical signal of the first band at the working moment, the corresponding second quantum key distribution subunit is triggered to send a quantum signal of the second band, and the classical signal and the quantum signal are combined and divided through the wavelength division multiplexing interface to reach the optical distribution network, and the optical customized switch opens the channel corresponding to the currently working optical network unit, so that the quantum signal passes through the optical customized switch, and

[0091] The quantum key is shared between the optical line terminal and the optical network unit by reaching the first quantum key distribution unit or pairing with the quantum signal sent by the first quantum key distribution unit.

[0092] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0093] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0094] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0095] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0096] Obviously, the above embodiments are merely examples for the purpose of clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A common fiber quantum key distribution system, arranged in a passive optical network, wherein the passive optical network comprises an optical line terminal, an optical distribution network and a plurality of optical network units, It is characterized in that The co-fiber quantum key distribution system comprises: A first quantum key distribution unit, deployed in the optical line terminal; A second quantum key distribution unit, including a plurality of second quantum key distribution sub-units, which are correspondingly deployed in the plurality of optical network units; An optical splitter, deployed in the optical distribution network; An optical customized switch, deployed in the optical distribution network; wherein the optical customized switch comprises: a switching control module, used to detect the currently working optical network unit and output a control signal; a connection module, connected to the switching control module, used to switch the quantum signal line to the currently working optical network unit detected by the switching control module according to the control signal; the switching control module comprises: a plurality of optical splitters, correspondingly connected to the plurality of optical network units through a wavelength division multiplexing interface, used to separate a part of the light intensity from the classical signal according to a preset ratio, and send the remaining classical signal to the optical splitter; a multi-channel photoelectric detector, wherein a plurality of input channels are respectively connected to the plurality of optical splitters, used to detect the currently working optical network unit according to the light intensity; and A wavelength division multiplexing interface, deployed on the optical line terminal, the optical distribution network and the plurality of optical network units, to support co-fiber communication between the optical line terminal and the optical distribution network, and between the optical distribution network and the plurality of optical network units; When any optical network unit sends a classical signal of the first band at the working moment, the corresponding second quantum key distribution subunit is triggered to send a quantum signal of the second band, and the classical signal and the quantum signal are combined and divided through the wavelength division multiplexing interface to reach the optical distribution network, and the optical customized switch opens the channel corresponding to the currently working optical network unit, so that the quantum signal passes through the optical customized switch, and The quantum key is shared between the optical line terminal and the optical network unit by reaching the first quantum key distribution unit or pairing with the quantum signal sent by the first quantum key distribution unit.

2. The common fiber quantum key distribution system according to claim 1, It is characterized in that Based on the preparation-measurement protocol, that is, the second quantum key distribution unit is a quantum key distribution transmitting end, and the first quantum key distribution unit is a quantum key distribution receiving end.

3. The co-fiber quantum key distribution system according to claim 1, It is characterized in that Based on a quantum relay-type quantum key distribution protocol, that is, the first quantum key distribution unit and the second quantum key distribution unit are both quantum key distribution transmitting ends, and a quantum measurement device is deployed between the output end of the optical custom switch and the wavelength division multiplexing interface.

4. The co-fiber quantum key distribution system according to claim 1, It is characterized in that Based on a quantum relay-type quantum key distribution protocol, the first quantum key distribution unit and the second quantum key distribution unit are both quantum key distribution transmitting ends, and a quantum measurement device is deployed between the first quantum key distribution unit and the wavelength division multiplexing interface.

5. The common fiber quantum key distribution system according to claim 1, It is characterized in that The isolation of the wavelength division multiplexing interface is not less than 60dB.

6. A passive optical network, It is characterized in that include: The optical line terminal side includes an optical line terminal, a first quantum key distribution unit and a wavelength division multiplexing interface; The optical network unit side includes several optical network units, and a second quantum key distribution subunit and a wavelength division multiplexing interface configured corresponding to each optical network unit; An optical distribution network, including an optical splitter, an optical custom switch, and wavelength division multiplexing interfaces respectively arranged towards an optical line terminal side and an optical network unit side; When any optical network unit sends a classical signal of the first band at the working moment, the corresponding second quantum key distribution subunit is triggered to send a quantum signal of the second band, and the classical signal and the quantum signal are combined and divided through the wavelength division multiplexing interface to reach the optical distribution network, and the optical customized switch opens the channel corresponding to the currently working optical network unit, so that the quantum signal passes through the optical customized switch, and The quantum key is shared between the optical line terminal and the optical network unit by reaching the first quantum key distribution unit or pairing with the quantum signal sent by the first quantum key distribution unit.

7. A common fiber quantum key distribution method, It is characterized in that include: When the second quantum key distribution subunit in the common fiber quantum key distribution system as claimed in any one of claims 1 to 5 is triggered by the classical signal of the first band sent by the corresponding optical network unit at the working time, a quantum signal of the second band is sent; When the classical signal and the quantum signal are combined and split through the wavelength division multiplexing interface and reach the optical distribution network, the channel corresponding to the currently working optical network unit is opened by using the optical custom switch, so that the quantum signal passes through the optical custom switch, and The quantum key is shared between the optical line terminal and the optical network unit by reaching the first quantum key distribution unit or pairing with the quantum signal sent by the first quantum key distribution unit.

8. The co-fiber quantum key distribution method according to claim 7, It is characterized in that The step of using the optical customized switch to open the channel corresponding to the currently working optical network unit so that the quantum signal passes through the optical customized switch includes: The switching control module is used to detect the currently working optical network unit, and the connection module is controlled to switch the quantum signal line to connect with the detected currently working optical network unit.

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