A time phase quantum key distribution system and its transmitter structure

Abstract

The present invention provides a time phase quantum key distribution system and a transmitter structure thereof, wherein the transmitter structure comprises: a direct modulation laser module for outputting continuous optical pulses; at least one electro-absorption modulator module for modulating the light intensity of the optical pulse output by the direct modulation laser module; an optical attenuator for attenuating the light intensity of the optical pulse output by the electro-absorption modulator module; wherein the direct modulation laser module and at least one electro-absorption modulator module are integrated on the same chip. That is to say, in the present application, the quantum key distribution system originally based on each independent optical device is integrated in a chip with a relatively small volume, thereby greatly reducing the cost of the quantum key distribution system and greatly reducing the volume of the quantum key distribution system.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and more specifically, to a time phase quantum key distribution system and a transmitting end structure thereof. Background Art

[0002] Quantum cryptography combines the principles of quantum physics and modern communication technology. Quantum cryptography uses physical principles to ensure the security of the remote key negotiation process and results. Combined with the "one-time-one-pad" encryption technology, it can achieve confidential communication that does not rely on the complexity of the algorithm.

[0003] At present, quantum cryptography technology uses light quanta as the implementation carrier and distributes them through free space or optical fiber channels; classical random bits are recorded on physical quantities such as polarization and phase of light quanta through polarization encoding, phase encoding and other methods.

[0004] In the current existing technologies, quantum key distribution systems are mainly divided into two categories: discrete variable quantum key distribution systems and continuous variable quantum key distribution systems. Since fiber-optic communication has become the infrastructure and development trend of modern information transmission, quantum cryptographic communication in fiber-optic channels has very important significance and application prospects, and device-based quantum key distribution systems have gradually been deployed around the world to provide quantum key distribution services to the public.

[0005] Existing practical quantum key distribution systems generally include a transmitter and a receiver. The transmitter is used to encode the key on a photon, while the receiver is used to decode and measure the photon.

[0006] However, existing quantum key distribution devices still have some problems, which prevent them from being put into practical use on a large scale. The most important problems include the large size of the equipment. For a commercial key distribution system with a GHz repetition frequency, its volume can generally reach the size of a 3U chassis. Secondly, the equipment cost is relatively high. Generally, the price of a single device of a quantum key distribution system with a GHz repetition frequency can reach more than one million.

[0007] The above two problems are mainly due to the fact that the optical and electronic parts of the existing quantum key distribution systems are all implemented based on discrete optical components and PCB circuit boards. This implementation method is costly and results in a larger device size. Summary of the invention

[0008] In view of this, in order to solve the above problems, the present invention provides a time phase quantum key distribution system and a transmitter structure thereof, and the technical solution is as follows:

[0009] A transmitting end structure of a time phase quantum key distribution system, the transmitting end structure comprising:

[0010] Direct-modulated laser module for outputting continuous light pulses;

[0011] At least one electro-absorption modulator module, used to modulate the intensity of the optical pulse output by the direct-modulated laser module;

[0012] An optical attenuator, used to attenuate the light intensity of the optical pulse output by the electro-absorption modulator module;

[0013] Wherein, the directly modulated laser module and at least one of the electro-absorption modulator modules are integrated on the same chip.

[0014] Preferably, in the above transmitting end structure, the number of the electro-absorption modulator modules is two;

[0015] The first electro-absorption modulator module is used to perform a first modulation on the intensity of the optical pulse output by the direct-modulation laser module;

[0016] The second electro-absorption modulator module is used to perform a second modulation on the intensity of the optical pulse output by the first electro-absorption modulator module.

[0017] Preferably, in the above transmitting end structure, the optical attenuator is used to attenuate the light intensity of the optical pulse output by the second electro-absorption modulator module.

[0018] Preferably, in the above transmitting end structure, the chip includes:

[0019] substrate;

[0020] An N-type doped layer disposed on one side of the substrate;

[0021] A multi-quantum well layer disposed on a side of the N-type doped layer away from the substrate;

[0022] A P-type doped layer disposed on a side of the multi-quantum well layer away from the substrate;

[0023] A plurality of independent metal electrodes are arranged on the side of the P-type doping layer away from the substrate, and an isolation groove is arranged on the P-type doping layer between two adjacent metal electrodes.

[0024] Preferably, in the above-mentioned emitter end structure, the multi-quantum well layer is an indium gallium arsenide multi-quantum well layer.

[0025] Preferably, in the above transmitting end structure, the number of the electro-absorption modulator modules is M;

[0026] The number of the metal electrodes is N;

[0027] Among them, N=M+1.

[0028] Preferably, in the above-mentioned transmitting end structure, the directly modulated laser module at least includes a distributed feedback semiconductor laser light source.

[0029] A time phase quantum key distribution system, the time phase quantum key distribution system comprising a transmitting end structure and a receiving end structure;

[0030] The transmitting end structure includes any one of the transmitting end structures described above.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The transmitting end structure of a time phase quantum key distribution system provided by the present invention includes: a direct-modulated laser module for outputting continuous optical pulses; at least one electro-absorption modulator module for modulating the light intensity of the optical pulse output by the direct-modulated laser module; an optical attenuator for attenuating the light intensity of the optical pulse output by the electro-absorption modulator module; wherein the direct-modulated laser module and at least one electro-absorption modulator module are integrated on the same chip. That is to say, in the present application, the quantum key distribution system originally based on each independent optical device is integrated into a chip with a smaller volume, thereby greatly reducing the cost of the quantum key distribution system and greatly reducing the volume of the quantum key distribution system. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0034] Figure 1 A schematic diagram of the principle structure of a transmitter structure of a time phase quantum key distribution system provided by an embodiment of the present invention;

[0035] Figure 2 A method provided by an embodiment of the present invention Figure 1 A schematic top view of a chip showing a transmitter structure;

[0036] Figure 3 A method provided by an embodiment of the present invention Figure 1 A schematic diagram of a chip cross section showing a transmitter structure;

[0037] Figure 4 A schematic diagram of the principle structure of a transmitter of another time phase quantum key distribution system provided by an embodiment of the present invention;

[0038] Figure 5A method provided by an embodiment of the present invention Figure 4 A schematic top view of a chip showing a transmitter structure;

[0039] Figure 6 A method provided by an embodiment of the present invention Figure 4 A schematic diagram of a chip cross section showing a transmitter structure;

[0040] Figure 7 A schematic diagram of three light quantity states of a three-state time phase encoding provided by an embodiment of the present invention;

[0041] Figure 8 A method provided by an embodiment of the present invention Figure 1 Schematic diagram of the modulation scheme of the transmitter structure shown;

[0042] Fig. 9 Another embodiment of the present invention provides Figure 1 Schematic diagram of the modulation scheme of the transmitter structure shown;

[0043] Fig.10 A method provided by an embodiment of the present invention Figure 4 Schematic diagram of the modulation scheme of the transmitter structure shown;

[0044] Fig.11 Another embodiment of the present invention provides Figure 4 Schematic diagram of the modulation scheme of the transmitter structure shown;

[0045] Fig.12 A schematic diagram of the principle structure of a time phase quantum key distribution system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0048] refer to Figure 1 , Figure 1 A schematic diagram of the principle structure of a transmitter structure of a time phase quantum key distribution system provided in an embodiment of the present invention.

[0049] The transmitting end structure comprises:

[0050] Direct-modulated laser module for outputting continuous light pulses;

[0051] At least one electro-absorption modulator module, used to modulate the intensity of the optical pulse output by the direct-modulated laser module;

[0052] An optical attenuator, used to attenuate the light intensity of the optical pulse output by the electro-absorption modulator module;

[0053] Wherein, the directly modulated laser module and at least one of the electro-absorption modulator modules are integrated on the same chip.

[0054] In this embodiment, the embodiment of the present invention proposes a transmitter structure of a time phase quantum key distribution system with a simple structure and easy on-chip integration for the time phase BB84 quantum key distribution protocol.

[0055] Among them, the directly modulated laser module can be a distributed feedback (DFB) semiconductor laser light source based on Group III-V semiconductors. By directly modulating the current pulse, the laser can be operated in a gain switching mode to generate continuous light pulses that are independent of the phases of the previous and next pulses.

[0056] The electro-absorption modulator module can be a device based on the quantum-confined Stark effect in a semiconductor quantum well structure, which has an absorption effect on a light beam after voltage is applied. By means of voltage pulse modulation, the intensity of an incoming light beam can be modulated.

[0057] An optical attenuator is used to reduce the light intensity of a light beam. For a quantum key distribution system, it is generally necessary to attenuate the outgoing light pulse to the single photon level.

[0058] like Figure 1 As shown, the number of the electro-absorption modulator modules is two.

[0059] The first electro-absorption modulator module 1 is used to perform a first modulation on the intensity of the optical pulse output by the direct-modulation laser module.

[0060] The second electro-absorption modulator module 2 is used to perform a second modulation on the intensity of the optical pulse output by the first electro-absorption modulator module.

[0061] The optical attenuator is used to attenuate the light intensity of the optical pulse output by the second electro-absorption modulator module 2 .

[0062] refer to Figure 2 , Figure 2 A method provided by an embodiment of the present invention Figure 1 The schematic diagram of the chip top view of the transmitter structure shown; refer to Figure 3 , Figure 3 A method provided by an embodiment of the present invention Figure 1 Schematic diagram of the chip cross-section of the transmitter structure shown.

[0063] based on Figure 1 The transmitter structure shown in the figure implements structures such as a direct-modulated laser module and two electro-absorption modulator modules on a chip using chip integration technology.

[0064] Optionally, the chip may be an InP-based chip.

[0065] like Figure 3 As shown, the chip includes:

[0066] Base.

[0067] An N-type doped layer is disposed on one side of the substrate.

[0068] A multi-quantum well layer is arranged on the side of the N-type doped layer away from the substrate.

[0069] A P-type doped layer is arranged on a side of the multi-quantum well layer away from the substrate.

[0070] A plurality of independent metal electrodes are arranged on the side of the P-type doping layer away from the substrate, and an isolation groove is arranged on the P-type doping layer between two adjacent metal electrodes.

[0071] Optionally, the multi-quantum well layer is an indium gallium arsenide multi-quantum well layer.

[0072] The number of the electroabsorption modulator modules is M; the number of the metal electrodes is N.

[0073] Among them, N=M+1.

[0074] like Figure 3 As shown, M=2, N=3.

[0075] Optionally, in another embodiment of the present invention, refer to Figure 4 , Figure 4 A schematic diagram of the principle structure of a transmitter structure of another time phase quantum key distribution system provided in an embodiment of the present invention.

[0076] The transmitter structure can be simplified by increasing the complexity of the electronic modulation, such as Figure 4 As shown, the number of the electro-absorption modulator module is one, that is, there is only the electro-absorption modulator module 1.

[0077] refer to Figure 5 , Figure 5 A method provided by an embodiment of the present invention Figure 4 The schematic diagram of the chip top view of the transmitter structure shown; refer to Figure 6, Figure 6 A method provided by an embodiment of the present invention Figure 4 Schematic diagram of the chip cross-section of the transmitter structure shown.

[0078] based on Figure 4 The transmitter structure shown in the figure implements structures such as a direct-modulated laser module and an electro-absorption modulator module on a chip using chip integration technology.

[0079] Optionally, the chip may be an InP-based chip.

[0080] like Figure 6 As shown, the chip includes:

[0081] Base.

[0082] An N-type doped layer is disposed on one side of the substrate.

[0083] A multi-quantum well layer is arranged on the side of the N-type doped layer away from the substrate.

[0084] A P-type doped layer is arranged on a side of the multi-quantum well layer away from the substrate.

[0085] A plurality of independent metal electrodes are arranged on the side of the P-type doping layer away from the substrate, and an isolation groove is arranged on the P-type doping layer between two adjacent metal electrodes.

[0086] Optionally, the multi-quantum well layer is an indium gallium arsenide multi-quantum well layer.

[0087] The number of the electroabsorption modulator modules is M; the number of the metal electrodes is N.

[0088] Among them, N=M+1.

[0089] like Figure 3 As shown, M=1, N=2.

[0090] Specifically, the transmitting end structure of the quantum key distribution system is used to encode the key on the photon, and the receiving end structure is used to decode and measure the photon. Therefore, for the transmitting end structure of the quantum key distribution system, it is generally necessary to use modulation methods such as phase modulation or polarization modulation to modulate the photon into different states, and different photon states represent different coded information.

[0091] Time phase encoding is one of the quantum state encoding methods, see Figure 7 , Figure 7 Schematic diagram of three light states of a three-state time phase coding provided by an embodiment of the present invention. For time phase coding, they are respectively the state |0> and the state |1> in the Z basis, and the state |0> in the X basis.

[0092] The two states in the Z basis respectively indicate that the optical pulse only exists at the earlier timestamp or the later timestamp; the state in the X basis indicates that the optical pulse exists at both the earlier and later timestamps, and the two optical pulses are in continuous phase.

[0093] The light intensity corresponding to these three states is the same, which means that for the X basis The light energy of the two pulses before and after is the same as the light energy of the two states in the Z basis.

[0094] In addition to the preparation of the above three quantum states, in order to resist beam splitting attacks, it is necessary to modulate the quantum state into a decoy state. In the embodiment of the present invention, the double-intensity decoy state is used for explanation, wherein the double-intensity decoy state modulation is to modulate the quantum state into a certain ratio p i (i=1,2), randomly modulate the output quantum light intensity, and modulate the output light intensity of a certain state to μ 1 and μ 2 Any light intensity output.

[0095] For the transmitter structure of the time phase quantum key distribution system, these states need to be modulated accordingly, which is described in detail below through multiple specific implementations:

[0096] Implementation method 1:

[0097] by Figure 1 The transmitter structure shown in the figure is used as an example to illustrate. Figure 8 , Figure 8 A method provided by an embodiment of the present invention Figure 1 Schematic diagram of the modulation scheme of the transmitter structure shown, running a three-state time phase protocol and performing dual-intensity decoy state modulation.

[0098] Specifically, a periodic current signal is used to drive the direct-modulated laser module. At this time, the laser is in a gain switching working mode. In this mode, the phases between adjacent pulses are randomized, meeting the phase randomization requirements of the quantum key distribution system for adjacent quantum states.

[0099] The first electroabsorption modulator module 1 randomly modulates the incident light pulse by varying the modulation voltage, thereby randomly generating the three quantum states mentioned above, for example Figure 8 As shown, when the light pulse is in the high level state, it passes, and when it is in the low level state, it is absorbed. The energy of the outgoing light can be adjusted by adjusting different levels. At the same time, under this intensity adjustment, if an original light pulse is adjusted into two light pulses, then the phases of the two light pulses are continuous, which meets the requirements of quantum key distribution quantum state preparation.

[0100] The second electroabsorption modulator module 2 performs dual-intensity entrapped state modulation. The second electroabsorption modulator module modulates the intensity of the incident quantum state by randomly selecting two modulation voltages of different magnitudes, respectively, at a certain ratio p i (i=1,2) Randomly modulate the output quantum light intensity and modulate the output light intensity of a certain state to μ 1 and μ 2 Any light intensity output.

[0101] After the above modulation is completed, an optical attenuator is used to decay the quantum state into a single-photon quantum output.

[0102] Implementation method 2:

[0103] by Figure 1 The transmitter structure shown in the figure is used as an example to illustrate. Fig. 9 , Fig. 9 Another embodiment of the present invention provides Figure 1 Schematic diagram of the modulation scheme of the transmitter structure shown, running a three-state time phase protocol and performing three-intensity decoy state modulation.

[0104] Specifically, compared with the double-intensity decoy state modulation, the triple-intensity decoy state modulation adds a vacuum state, that is, i (i=1,2,3) Randomly modulate the output quantum light intensity, and make the output light of a certain state into μ 1 , μ 2 and μ 3 Any light intensity output in 3 =0.

[0105] Among them, a periodic current signal is used to drive the direct-modulated laser module. Compared with the first embodiment, the p 3 The probability of randomly selecting part of the pulse time without driving the laser, thus making the light intensity μ 3 =0; at this time, the laser is in the gain switching mode, in which the phases between adjacent pulses are randomized, meeting the phase randomization requirements of the quantum key distribution system for adjacent quantum states.

[0106] The first electroabsorption modulator module 1 randomly modulates the incident light pulse by varying the modulation voltage, thereby randomly generating the three quantum states mentioned above, for example Fig. 9 As shown, when the light pulse is in the high level state, it passes, and when it is in the low level state, it is absorbed. The energy of the outgoing light can be adjusted by adjusting different levels. At the same time, under this intensity adjustment, if an original light pulse is adjusted into two light pulses, then the phases of the two light pulses are continuous, which meets the requirements of quantum key distribution quantum state preparation.

[0107] The second electroabsorption modulator module 2 performs dual-intensity entrapped state modulation. The second electroabsorption modulator module modulates the intensity of the incident quantum state by randomly selecting two modulation voltages of different magnitudes, respectively, at a certain ratio p i (i=1,2) Randomly modulate the output quantum light intensity and modulate the output light intensity of a certain state to μ 1 and μ 2 Any light intensity output.

[0108] After the above modulation is completed, an optical attenuator is used to decay the quantum state into a single-photon quantum output.

[0109] Implementation method three:

[0110] by Figure 4 The transmitter structure shown in the figure is used as an example to illustrate. Fig.10 , Fig.10 A method provided by an embodiment of the present invention Figure 4 Schematic diagram of the modulation scheme of the transmitter structure shown, running a three-state time phase protocol and performing three-intensity decoy state modulation.

[0111] Specifically, a periodic current signal is used to drive the direct-modulated laser module. At this time, the laser is in a gain switching working mode. In this mode, the phases between adjacent pulses are randomized, meeting the phase randomization requirements of the quantum key distribution system for adjacent quantum states.

[0112] The first electroabsorption modulator module 1 randomly modulates the incident light pulse by varying the modulation voltage, thereby randomly generating the three quantum states mentioned above, for example Fig.10 As shown, when the light pulse is in the high level state, it passes, and when it is in the low level state, it is absorbed. The energy of the outgoing light can be adjusted by adjusting different levels. At the same time, under this intensity adjustment, if an original light pulse is adjusted into two light pulses, then the phases of the two light pulses are continuous, which meets the requirements of quantum key distribution quantum state preparation.

[0113] After the above modulation is completed, an optical attenuator is used to decay the quantum state into a single-photon quantum output.

[0114] Implementation method 4:

[0115] by Figure 4 The transmitter structure shown in the figure is used as an example to illustrate. Fig.11 , Fig.11 Another embodiment of the present invention provides Figure 4 Schematic diagram of the modulation scheme of the transmitter structure shown, running a three-state time phase protocol and performing three-intensity decoy state modulation.

[0116] Specifically, the periodic current signal is used to drive the direct-modulated laser module. Compared with the third embodiment, the p 3 The probability of randomly selecting part of the pulse time without driving the laser, thus making the light intensity μ 3 =0; at this time, the laser is in the gain switching mode, in which the phases between adjacent pulses are randomized, meeting the phase randomization requirements of the quantum key distribution system for adjacent quantum states.

[0117] The first electroabsorption modulator module 1 randomly modulates the incident light pulse by varying the modulation voltage, thereby randomly generating the three quantum states mentioned above, for example Fig.11 As shown, when the light pulse is in the high level state, it passes, and when it is in the low level state, it is absorbed. The energy of the outgoing light can be adjusted by adjusting different levels. At the same time, under this intensity adjustment, if an original light pulse is adjusted into two light pulses, then the phases of the two light pulses are continuous, which meets the requirements of quantum key distribution quantum state preparation.

[0118] After the above modulation is completed, an optical attenuator is used to decay the quantum state into a single-photon quantum output.

[0119] Optionally, based on all the above embodiments of the present invention, another embodiment of the present invention further provides a time phase quantum key distribution system, referring to Fig.12 , Fig.12 A schematic diagram of the principle structure of a time phase quantum key distribution system provided by an embodiment of the present invention.

[0120] The time phase quantum key distribution system comprises a transmitting end structure and a receiving end structure.

[0121] The transmitting end structure includes the transmitting end structure described in the above embodiment.

[0122] It should be noted that an optical channel is provided between the transmitting end structure and the receiving end structure. Fig.12 The transmitter structure is Figure 4 The transmitter structure shown is used as an example for explanation.

[0123] The receiving end structure has multiple single-photon detectors (three single-photon detectors are used as an example in the embodiment of the present invention), unequal-arm interferometers, optical fiber splitters and other components. Various quantum states emitted by the transmitting end structure are transmitted to the receiving end structure through the optical fiber channel. They first pass through an optical fiber splitter, which splits the incident quantum state according to a certain proportion. For example, 10% of the quantum states will be transmitted upward into the unequal-arm interferometer for interference, and then the detection results will enter the single-photon detector 1 and the single-photon detector 2, and the remaining 90% of the quantum states will be transmitted downward and detected by the single-photon detector 3.

[0124] At this time, single photon detector 1 and single photon detector 2 are based on the quantum state X. The state is measured, and the single-photon detector 3 measures the state |0> and the state |1> in the Z basis.

[0125] Subsequently, based on the current measurement results and the basis comparison results of the transmitting and receiving end structures, error estimation and post-processing such as confidentiality amplification are performed, and finally a security key can be generated.

[0126] The time phase quantum key distribution system and the transmitter structure thereof provided by the present invention are introduced in detail above. The principle and implementation mode of the present invention are explained in this article by using specific examples. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation mode and the scope of application. In summary, the content of this specification should not be understood as limiting the present invention.

[0127] It should be noted that each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0128] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device that includes a series of elements is inherent to the elements, or also includes elements inherent to these processes, methods, articles or devices. In the absence of further restrictions, the elements defined by the sentence "including a..." do not exclude the presence of other identical elements in the process, method, article or device that includes the elements.

[0129] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A transmitting end structure of a time phase quantum key distribution system, characterized in that: The transmitting end structure comprises: Direct-modulated laser module for outputting continuous light pulses; At least one electro-absorption modulator module, used to modulate the intensity of the optical pulse output by the direct-modulated laser module; An optical attenuator, used to attenuate the light intensity of the optical pulse output by the electro-absorption modulator module; Wherein, the directly modulated laser module and at least one of the electro-absorption modulator modules are integrated on the same chip; The chip is an InP-based chip, and comprises: a substrate; an N-type doped layer arranged on one side of the substrate; a multi-quantum well layer arranged on the side of the N-type doped layer away from the substrate; a P-type doped layer arranged on the side of the multi-quantum well layer away from the substrate; a plurality of independent metal electrodes arranged on the side of the P-type doped layer away from the substrate, and an isolation groove is arranged on the P-type doped layer between two adjacent metal electrodes; There are two electro-absorption modulator modules; the first electro-absorption modulator module is used to perform a first modulation on the intensity of the optical pulse output by the direct-modulated laser module; the second electro-absorption modulator module is used to perform a second modulation on the intensity of the optical pulse output by the first electro-absorption modulator module; The transmitting end structure of the time phase quantum key distribution system runs a three-state time phase protocol and performs dual-intensity decoy state modulation, or runs a three-state time phase protocol and performs three-intensity decoy state modulation; specifically: The first electroabsorption modulator module runs the three-state temporal phase protocol to randomly modulate the incident light pulse by varying the modulation voltage, thereby randomly generating the state |0> and state |1> in the Z basis, and the state |1> in the X basis. The second electroabsorption modulator module performs the dual-intensity entrapped state modulation by randomly selecting two modulation voltages of different magnitudes to modulate the intensity of the incident quantum state at a certain ratio p i Randomly modulate the output quantum light intensity, i = 1, 2, and modulate the output light intensity of a certain state to any one of μ1 and μ2; or, the second electro-absorption modulator module performs the three-intensity entrapped state modulation, and modulates the intensity of the incident quantum state by randomly selecting three modulation voltages of different sizes, with a certain ratio p i The output quantum light intensity is modulated randomly, i=1,2,3, and the output light intensity of a certain state is emphasized to be any one of μ1, μ2 and μ3, where μ3=0.

2. The transmitting end structure according to claim 1, characterized in that: The optical attenuator is used to attenuate the light intensity of the optical pulse output by the second electro-absorption modulator module.

3. The transmitting end structure according to claim 1, characterized in that: The multi-quantum well layer is an InGaAs multi-quantum well layer.

4. The transmitting end structure according to claim 1, characterized in that: The number of the electroabsorption modulator modules is M; The number of the metal electrodes is N; Among them, N=M+1.

5. The transmitting end structure according to claim 1, characterized in that: The directly modulated laser module at least comprises a distributed feedback semiconductor laser light source.

6. A time phase quantum key distribution system, characterized in that: The time phase quantum key distribution system includes a transmitting end structure and a receiving end structure; Wherein, the transmitting end structure includes the transmitting end structure described in any one of claims 1-5.

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