CN111049613B - Device and method for time division multiplexing - Google Patents
Device and method for time division multiplexing Download PDFInfo
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- CN111049613B CN111049613B CN201911221472.9A CN201911221472A CN111049613B CN 111049613 B CN111049613 B CN 111049613B CN 201911221472 A CN201911221472 A CN 201911221472A CN 111049613 B CN111049613 B CN 111049613B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J3/00—Time-division multiplex systems
- H04J3/16—Time-division multiplex systems in which the time allocation to individual channels within a transmission cycle is variable, e.g. to accommodate varying complexity of signals, to vary number of channels transmitted
- H04J3/1676—Time-division multiplex with pulse-position, pulse-interval, or pulse-width modulation
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- 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
- H04B10/516—Details of coding or modulation
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- 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
- H04B10/516—Details of coding or modulation
- H04B10/524—Pulse modulation
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- 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
- H04B10/60—Receivers
- H04B10/66—Non-coherent receivers, e.g. using direct detection
- H04B10/69—Electrical arrangements in the receiver
- H04B10/691—Arrangements for optimizing the photodetector in the receiver
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- 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
Abstract
The application discloses a device and a method for time division multiplexing. The device for demultiplexing the time division multiplexing comprises an optical detection unit, a signal processing unit and a signal processing unit, wherein the optical detection unit receives the time division multiplexing light and detects the time division multiplexing light, and converts the time division multiplexing light into a time division multiplexing electric signal; the clock distribution unit comprises one path of signal input ports and two or more paths of signal output ports, and can output the input electric signals through different output ports after frequency division; a programmable unit configured to emit a first control signal for detecting a synchronous electrical signal, a second control signal for detecting a classical electrical signal; the first logic unit and the second logic unit comprise two or more signal input ports, and one signal output port can perform logic operation. The system has simple structure and reduces the application cost; the code rate of classical signals and synchronous signals is improved; the influence of the Raman scattering of the system on the quantum light is effectively reduced, so that the code rate of the quantum key is improved.
Description
Technical Field
The application relates to the technical field of quantum secret communication, in particular to a device and a method for demultiplexing time division multiplexing.
Background
The quantum secret communication technology is used as an emerging technology developed on the basis of quantum mechanics, modern communication, modern cryptography and the like, and based on the basic principle of quantum mechanics, the information is encrypted by using a one-time secret mode, so that the quantum secret communication technology has the characteristic of indecipherable and has incomparable safety advantages. Quantum key distribution (Quantum Key Distribution, QKD) technology is a key technology for quantum secure communications. One of the key research problems of the quantum key distribution technology at present is how to realize quantum key distribution by using the existing optical fiber communication network.
In the prior art, a quantum key distribution technology using a time division multiplexing technology realizes quantum key distribution by using an existing optical fiber communication network, and after a receiving end of the prior art receives signal light of a transmitting end, a time division demultiplexing device is required to perform time division multiplexing, and fig. 1 shows a schematic diagram of the time division demultiplexing device in the prior art. After receiving the optical signal from the transmitting end, the time division demultiplexing device of the prior art shown in fig. 1 performs a time division demultiplexing process, firstly, the light division device splits the time division multiplexed light, and then transmits the split signal light to the synchronous optical detector, the classical optical detector and the quantum key detector through channels, so as to obtain the synchronous signal, the classical signal and the quantum key by detecting the signal light respectively. Such a demultiplexing device causes the following problems. Firstly, the prior art de-time multiplexing device needs a light splitting device, and synchronous light and classical light need different light detectors to detect respectively, so that the device has a complex structure and high cost; secondly, in the prior art, synchronous light and classical light are detected by light splitting to obtain synchronous signals and classical signals, and the attenuation or phase shift of the light is caused in the light splitting process, so that the code rate of the synchronous signals and the classical signals is reduced; thirdly, the light intensity generates larger attenuation effect in the light splitting process, so that the emission end is required to emit stronger light, and the raman scattering noise and the light intensity are in positive correlation, so that stronger raman scattering effect is generated, and the quantum key code rate is low.
Disclosure of Invention
Aiming at the technical problems in the prior art, the application provides a device for demultiplexing time division multiplexing, which comprises: an optical detection unit configured to receive time-division multiplexed light and detect, and convert the time-division multiplexed light into a time-division multiplexed electrical signal; the clock distribution unit comprises a signal input port and two or more signal output ports, wherein the signal input ports are configured to receive the time division multiplexing electric signals, distribute the time division multiplexing electric signals to form first time division multiplexing signals, and output second time division multiplexing signals; a programmable unit configured to emit a first control signal for detecting a synchronous electrical signal, a second control signal for detecting a classical electrical signal; the first logic unit comprises two or more signal input ports, one signal output port has a logic operation function, is configured to receive the first time division multiplexing signal, the first control signal and process and send out the synchronous electric signal; the second logic unit comprises two or more signal input ports, one signal output port has a logic operation function, is configured to receive the second time division multiplexing signal, and is used for processing the second control signal and sending out the classical electric signal.
The above-described apparatus for demultiplexing, the clock distribution unit is further a clock distributor.
The apparatus for demultiplexing as described above, the programmable unit may further include: a control chip configured to issue an operation instruction to the signal generating device or the delay device; a signal generating device configured to receive an operation instruction of the control chip, and generate an electrical signal; and the time delay device is configured to receive the operation instruction of the control chip, the electric signal generated by the signal generation device and perform time delay operation on the received electric signal according to the received operation instruction.
The above-described apparatus for demultiplexing, the light detection unit is further a PN junction type photodetector, or a PIN type photodetector, or an Avalanche Photodiode (APD) detector, or a pull-through type avalanche photodiode (RAPD) detector.
The above-described time division multiplexing device, the first logic unit or the second logic unit is further a logic chip.
The above-described time division multiplexing apparatus, the first logic unit or the second logic unit may be any one of an and circuit, an or circuit, a nor circuit, a nand circuit, a nor circuit, an exclusive or circuit, and an exclusive or circuit.
In the above-described demultiplexing device, the first logic unit or the second logic unit is further an and circuit.
In the above-described apparatus for demultiplexing time-division multiplexed signals, the signal characteristics of the first time-division multiplexed electrical signal and the second time-division multiplexed electrical signal are identical to the signal characteristics of the time-division multiplexed electrical signal.
According to another aspect of the present application, there is provided a method of demultiplexing, comprising: the light detection unit receives the time division multiplexing light and detects the time division multiplexing light, and the time division multiplexing light is converted into a time division multiplexing electric signal; receiving the time division multiplexed electrical signal by the clock distribution unit and distributing to form a first time division multiplexed electrical signal and a second time division multiplexed electrical signal; the programmable unit sends out a first control signal for detecting synchronous electric signals and a second control signal for detecting classical electric signals; the first time division multiplexing electric signal and the first control signal are input into the first logic unit and are processed, and then synchronous electric signals are output; the second time division multiplexing electric signal and the second control signal are input into the second logic unit, and after being processed, classical electric signals are output.
The device and the method for demultiplexing the time division multiplexing cancel the light-splitting device in the prior art, and can realize detection of classical light and synchronous light by one light detection unit, so that the system has simple structure and reduces the application cost. Compared with the prior art, the method detects the time division multiplexing light to obtain the time division multiplexing electric signal, then the synchronous electric signal and the classical electric signal are obtained through the processing of the logic unit, and the processing electric signal is simpler and more convenient than the optical signal, has higher precision and can improve the code rate of the signal. And the light intensity of the transmitting end when transmitting the signal light can be reduced compared with the prior art due to the cancellation of the light splitting device, so that the influence of the Raman scattering of the system on the quantum light can be effectively reduced, and the code rate of the quantum key is improved.
Drawings
Fig. 1 shows a schematic configuration of a demultiplexing device of a time division multiplexing quantum key distribution system of the related art;
fig. 2 shows a schematic structural diagram of an exemplary embodiment of a transmitting end according to the present application;
fig. 3 shows a schematic diagram of signal slot modulation at a transmitting end according to the present application;
fig. 4 shows a schematic structural diagram of an exemplary embodiment of a receiving end according to the present application;
fig. 5 shows a schematic structural diagram of an exemplary embodiment of an apparatus for demultiplexing according to the present application;
fig. 6 shows a schematic diagram of an initialization phase of a demultiplexing device according to the application;
fig. 7 shows an initialization phase signal diagram of a demultiplexing device according to the present application;
fig. 8 shows a schematic diagram of the operational phases of a time division demultiplexing device according to the application;
fig. 9 shows a signal diagram of the operating phase of the de-time multiplexing device according to the application;
fig. 10 shows a flow diagram of a method of demultiplexing according to the application.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments of the application. In the drawings, like reference numerals describe substantially similar components throughout the different views. Various specific embodiments of the application are described in sufficient detail below to enable those skilled in the art to practice the teachings of the application.
Fig. 2 shows a schematic structural diagram of an exemplary embodiment of a transmitting end according to the present application. The basic structure of the transmitting end of the present application can be briefly described by the embodiment of fig. 2. As shown in fig. 2, the transmitting end of the present application may include a quantum key encoding unit 101, a first laser 103, and a first wavelength division multiplexing unit 201.
In some embodiments, the quantum key encoding unit 101 may receive the optical signal, perform quantum key encoding, and transmit the encoded quantum signal in the form of quantum light, where the quantum key encoding unit 101 may be a polarization encoding device, a time encoding device, a phase encoding device, or a time phase encoding device, preferably a time phase encoding device. The probability of quantum key encoding by the quantum key encoding unit 101 is random, and after quantum key encoding is completed, the wavelength of the period t is λ 1 The value range of the period t is 5ns less than or equal to t less than or equal to 60ns. The quantum key encoding unit 101 may include an encoding preparation means for receiving an optical signal to perform quantum key encoding; may include a decoy preparation device for decoy preparation; a single photon preparation device can be included to perform single photon preparation.
In some embodiments, the first laser 103 may emit light having the same wavelength λ 2 Wherein the synchronization light is operable to transmit the encoded synchronization signal and the classical light is operable to transmit the encoded classical signal. The first laser 103 may transmit the synchronization light during the initialization phase of the present application and transmit the synchronization light or classical light during the operation phase of the present application. The synchronous light emitted by the first laser 103 can transmit synchronous frames meeting the requirements of synchronous digital transmission, the digital synchronous transmission can adopt optical fiber channels to realize the functions of multi-node synchronous information transmission, multiplexing, add/drop multiplexing, cross connection and the like, the synchronous light emitted by the first laser 103 can be narrow pulse with the duty ratio less than or equal to 1%, further is narrow pulse with the duty ratio less than or equal to 1%o, the period of the synchronous light emitted by the first laser 103 is T1, and the numerical range of the period T1 is 5us less than or equal to T1 less than or equal to 30us; the classical light emitted by the first laser 103 may be a classical light pulse with a pulse width that may be modulated, the classical light being a narrow pulse with a duty cycle of 30% or less; preferably, the pulse is a narrow pulse with a duty cycle of 20% or lessThe method comprises the steps of carrying out a first treatment on the surface of the Further preferably a narrow pulse with a duty cycle of 10% or less; the period of classical light emitted by the first laser 103 is T2, and the value range of the period T2 is t.ltoreq.T2.ltoreq.T1.
The first laser 103 adopts a time division multiplexing technology in the process of emitting classical light and synchronous light, divides the channel transmission time into different time slots, and distributes the divided different time slots to the synchronous light and the classical light by the system, thereby realizing the time division multiplexing of the synchronous light and the classical light. The first laser 103 modulates the emitted synchronization light and classical light according to the time slot modulation scheme shown in fig. 3. The first laser 103 modulates the synchronization light according to the time slot diagram shown in the first row of fig. 3, and the synchronization light has a wavelength lambda shown in the first row of fig. 3 2 The period is T1, T1 is more than or equal to 5us and less than or equal to 30us; the first laser 103 modulates classical light according to the time slot diagram shown in the second row of fig. 3, with a classical light wavelength lambda shown in the second row of fig. 3 2 The period is T2, and T is more than or equal to T2 and less than or equal to T1; the first laser 103 performs time division multiplexing on the synchronous light and the classical light according to the time slot diagram shown in the third row of fig. 3, so as to realize time division multiplexing on the classical light and the synchronous light, and emits time division multiplexing light, wherein the time difference between the synchronous light and the adjacent classical light is deltat, and the value range of the time difference is T is less than or equal to deltat less than or equal to T1/2.
In some embodiments, the first wavelength division multiplexing unit 201 includes a first port C, a second port R, and a third port T. The first wavelength division multiplexing unit 201 is a bidirectional optical element, and can be set in the following modes: when light in the first frequency range is incident from the second port R and/or light in the second frequency range is incident from the third port T, the incident light of the second port R and the incident light of the third port T are combined into one path to be output at the first port C; when light is incident on the first port C, the second port R outputs light in the first frequency range, and the third port T outputs light in the second frequency range. Wherein the first frequency range may be different from the second frequency range.
The first wavelength division multiplexing unit 201 may be a sparse wavelength division multiplexer, a dense wavelength division multiplexer, a band pass wavelength division multiplexer, or a fiber bragg grating, but is not limited thereto. Since the sparse wavelength division multiplexer, the dense wavelength division multiplexer, and the band pass wavelength division multiplexer have a common port, a reflection port, and a transmission port, and the isolation of the transmission port is greater than that of the reflection port, it is preferable to use these three wavelength division multiplexers, and set the common port as the first port C, the reflection port as the second port R, and the transmission port as the third port T. Preferably, the first wavelength division multiplexing unit 201 may be a wavelength division multiplexer having an isolation of 60dB or more.
The quantum light emitted by the quantum key encoding unit 101 and the time division multiplexing light emitted by the first laser 103 can be selected to be the second port R input of the first wavelength division multiplexing unit 201 or the third port T input of the first wavelength division multiplexing unit 201, and the quantum light emitted by the quantum key encoding unit 101 can be further selected to be the third port T input of the first wavelength division multiplexing unit 201, so that the effect of local fluorescence on the quantum light can be eliminated by the transmission port with the largest isolation.
In the present application, the first laser 103 may emit light having a wavelength λ 2 Synchronous light with period of T1 and wavelength of lambda 2 Is modulated according to the time slot diagram shown in the first row of fig. 3, is modulated according to the time slot diagram shown in the second row of fig. 3, is time-division multiplexed with the synchronous light according to the time slot diagram shown in the third row of fig. 3, realizes the time-division multiplexing of the synchronous light and the classical light, and gives out a wavelength lambda 2 In the emitted time division multiplexing light, the numerical range of the time difference delta T between the synchronous light and the adjacent classical light is more than or equal to the period T of the quantum light and less than or equal to T1/2; the quantum key encoding unit 101 can perform quantum key encoding and emit light with wavelength lambda 1 Is t; wavelength lambda of time division multiplexed light 2 Wavelength lambda of quantum light 1 Are not equal; the first wavelength division multiplexing unit 201 can receive the wavelength lambda emitted by the first laser 103 2 The wavelength lambda of the time division multiplexing light and quantum key encoding unit 101 1 And performs wavelength division multiplexing on the time division multiplexed light and the quantum light, and then emits the wavelength division multiplexed light and transmits the same through a channel.
In the present application, the quantum light and the time division multiplexing light, that is, the quantum light and the classical light or the synchronous light have different wavelengths, and the wavelength division multiplexing can be performed, which means that the quantum light is not time division multiplexed, so that the problem that a relatively long 'clearing period' is required before the quantum light is emitted in the prior art is not generated, and therefore, the sending frequency of the quantum light is not affected by the time division multiplexing, and thus, the high-speed sending of the quantum key can be realized. In addition, the transmitting end of the application does not need to use a plurality of modulators to modulate classical light and synchronous light in time division multiplexing, thereby leading the system structure to be simple and reducing the cost.
Fig. 4 shows a schematic structural diagram of an exemplary embodiment of a receiving end according to the present application. As shown in fig. 4, the receiving end of the present application may include a second wavelength division multiplexing unit 203, a time division multiplexing device 301, and a quantum key decoding unit 303.
In some embodiments, the second wavelength division multiplexing unit 203 is a bidirectional optical element, and has a similar structure to the first wavelength division multiplexing unit 201, and the second wavelength division multiplexing unit 203 receives the wavelength division multiplexed light transmitted by the transmitting end of the present application and performs wavelength division multiplexing on the received wavelength division multiplexed light, wherein the resulting quantum light is transmitted to the quantum key decoding unit 303, and the resulting time division multiplexed light is transmitted to the demultiplexing device 301.
In some embodiments, the demultiplexing device 301 may receive the time division multiplexed light transmitted by the second wavelength division multiplexing unit 203, detect the received time division multiplexed light, convert the time division multiplexed light into a time division multiplexed electrical signal, and further process the time division multiplexed electrical signal to obtain a synchronous electrical signal and a classical electrical signal.
In some embodiments, the quantum key decoding unit 303 may receive the quantum light transmitted by the second wavelength division multiplexing unit 203 and detect the quantum light to decode the quantum key to obtain encoded information therein.
Fig. 5 shows a schematic structural diagram of an exemplary embodiment of an apparatus for demultiplexing according to the present application. As shown in fig. 5, the time division multiplexing apparatus of the present application may include a light detection unit 401, a clock distribution unit 501, a programmable unit 601, a first logic unit 603, and a second logic unit 605, wherein the programmable unit 601 may include a control chip 6011, a signal generation apparatus 6013, and a delay apparatus 6015.
In some embodiments, the light detection unit 401 may receive and detect the light signal and obtain a corresponding electrical signal, and the light detection unit 401 may be a PN junction type photodetector, a PIN type photodetector, an Avalanche Photodiode (APD) detector, or a pull-through type avalanche photodiode (RAPD) detector. The clock distribution unit 501 may include one signal input port, may include two or more signal output ports, and may distribute an input electrical signal according to a system requirement and output the signal through different output ports. Preferably, the clock distribution unit 501 may be a clock distributor.
In some embodiments, the programmable unit 601 may send out different signals according to different operation phases of the present application, may send out a scan signal during an initialization phase, and send out a control signal during an operation phase. The programmable unit 601 may include a control chip 6011, and may issue an operation instruction to the signal generating device 6013 or the delay device 6015; the signal generating device 6013 may receive an operation instruction of the control chip 6011, generate different electrical signals in different working phases of the present application, may send out a scan signal in an initialization phase, and send out a control signal in the working phase; the delay device 6015 may receive the operation instruction of the control chip 6011 and the electric signal generated by the signal generating device 6013, and perform a delay operation on the received electric signal according to the received operation instruction.
In some embodiments, the first logic unit 603 is a circuit capable of performing logic operation, which may be an and circuit, an or gate nor gate, or may be a nand gate, a nor gate, an exclusive or gate, or an exclusive or gate. The first logic unit 603 may include two or more signal input ports, and may include one signal output port. Preferably, the first logic unit 603 may be a logic chip. The second logic unit 605 has a similar structure and function as the first logic unit 603. Preferably, the first logic unit 603 and the second logic unit 605 may be and gates.
The inventive time division multiplexing device may have different modes of operation during the initialization phase or the operation phase of the application.
Fig. 6 shows a schematic diagram of an initialization phase of the demultiplexing device according to the present application, and fig. 7 shows a schematic diagram of an initialization phase signal of the demultiplexing device according to the present application. In the initialization phase of the present application, the first laser 103 emits a synchronization light, which is transmitted to the time division multiplexing device of the present application via a channel. The light detection unit 401 receives and detects the synchronization light, converts the synchronization light into a synchronization electrical signal shown in the first row of fig. 7, and the synchronization electrical signal has the same signal characteristics as the synchronization light such as period, wavelength, pulse width, duty ratio, frequency, and the like. The clock distribution unit 501 receives the synchronization electric signal and distributes to the first logic unit 603. In the initialization stage, the transmitting end of the application can transmit the information of the period, the pulse width and the like of the synchronous light to the de-time multiplexing device of the receiving end through a classical channel. After receiving the information of the period, the pulse width, and the like of the synchronization light, the programmable unit 601 sends a signal generation instruction to the signal generation device 6013 by the control chip 6011, randomly generates a scan signal as shown in the second row of fig. 7, which has the same period as the synchronization electric signal and has a pulse width 1.5 to 3 times the pulse width of the synchronization electric signal, and sends the scan signal to the first logic unit 603 via the delay device 6015. The first logic unit 603 performs and gate logic operation after receiving the synchronization signal and the scan signal. If the first logic unit 603 performs and gate operation and has no high level output, that is, the scanning signal does not scan the synchronous electric signal, the control chip 6011 instructs the delay device 6015 to perform delay operation for a certain time on the scanning signal generated by the signal generating device 6013 to obtain a scanning signal shown in a third line of fig. 7, and sends the scanning signal to the first logic unit 603, and then the first logic unit 603 performs and gate operation on the received synchronous electric signal and the scanning signal until there is high level output, at this time, the programmable unit 601 may generate a first control signal 705 as shown in a fourth line of fig. 7, which has the same period and the same frequency as the synchronous electric signal and has a pulse width 1.5 to 3 times that of the synchronous electric signal, for detecting the synchronous electric signal, and perform inverse operation on the first control signal 705 and generate a second control signal 707 as shown in a fifth line of fig. 7 for detecting the classical electric signal.
Fig. 8 shows a schematic diagram of the operational phases of a de-time multiplexing device according to the application. Fig. 9 shows a signal diagram of the operational phase of the de-time multiplexing device according to the application. As shown in fig. 9, the first line is a time-division multiplexed electrical signal, the second line is a first time-division multiplexed electrical signal 701, the third line is a second time-division multiplexed electrical signal 703, the fourth line is a first control signal 705, the fifth line is a second control signal 707, the sixth line is a synchronous electrical signal, and the seventh line is a classical electrical signal.
In the working phase of the present application, the optical detection unit 401 receives the time division multiplexed light sent by the sending end of the present application, detects the received time division multiplexed light, converts the time division multiplexed light into a time division multiplexed electrical signal, and obtains the time division multiplexed electrical signal as shown in the first row of fig. 9, where the obtained time division multiplexed electrical signal has the same signal characteristics of cycle, frequency, wavelength, duty cycle, pulse width, and the like as the time division multiplexed light. The clock distribution unit 501 may receive the time-division multiplexed electrical signal shown in the first row of fig. 9 and distribute the received time-division multiplexed electrical signal, and output a first time-division multiplexed electrical signal 701 shown in the second row of fig. 9 and a second time-division multiplexed electrical signal 703 shown in the third row of fig. 9, where the signal characteristics and values of the first time-division multiplexed electrical signal 701 and the second time-division multiplexed electrical signal 703 are consistent with those of the time-division multiplexed electrical signal. The first logic unit 603 receives a first time division multiplexed electrical signal 701 as shown in the second row of fig. 9 and a first control signal 705 issued by the programmable unit 601 as shown in the fourth row of fig. 9. The first logic unit 603 may perform and logic operation after receiving the first time division multiplexed electrical signal 701 and the first control signal 705, and output a synchronous electrical signal as shown in the sixth row of fig. 9, where the obtained synchronous electrical signal has the same signal characteristics as the synchronous light, such as a period, a frequency, a wavelength, a duty ratio, and a pulse width. The second logic unit 605 receives the second time division multiplexed electrical signal 703 as shown in the third row of fig. 9 and the second control signal 707 issued by the programmable unit 601 as shown in the fifth row of fig. 9. The second logic unit 605 may perform and gate logic operation after receiving the second time division multiplexed electrical signal 703 and the second control signal 707, and output a classical electrical signal as shown in the seventh row of fig. 9, where the obtained classical electrical signal has the same signal characteristics as the classical light, such as a period, a frequency, a wavelength, a duty cycle, and a pulse width.
Fig. 10 shows a flow diagram of a method of demultiplexing according to the application. As shown in fig. 10, the time division demultiplexing method of the present application may include the steps of:
s1001: the light detection unit 401 receives and detects the time division multiplexed light, and converts the time division multiplexed light into a time division multiplexed electrical signal;
s1002: the clock distribution unit 501 receives the time-division multiplexed electrical signal and distributes the time-division multiplexed electrical signal to form a first time-division multiplexed electrical signal 701 and a second time-division multiplexed electrical signal 703;
s1003: the programmable unit 601 generates a first control signal 705 for detecting a synchronous electrical signal, and a second control signal 707 for detecting a classical electrical signal;
s1004: the first time division multiplexing electrical signal 701 and the first control signal 705 are input into the first logic unit 603, and after performing and gate logic operation, a synchronous electrical signal is output; the second time division multiplexed electrical signal 703 and the second control signal 707 are input to the second logic unit 605, and the classic electrical signal is output after the and logic operation.
Compared with the prior art that different light detectors detect classical light and synchronous light respectively, the application can realize detection of the classical light and the synchronous light by one light detection unit, so that the system structure is very simple compared with the prior art, and the application cost is effectively reduced. In addition, compared with the prior art, the synchronous signal and the classical signal are detected from the signal light after light splitting, the method detects the time division multiplexing light to obtain the time division multiplexing electric signal, and the synchronous electric signal and the classical electric signal are obtained through processing of the first logic unit and the second logic unit which can perform logic operation. And the light intensity of the transmitting end when transmitting the signal light can be reduced to one third to one half compared with the light intensity of the time division multiplexing in the prior art due to the cancellation of the light splitting device, and the influence of the Raman scattering effect of the system on the quantum light can be effectively reduced due to the positive correlation between the Raman scattering effect and the light intensity, so that the code rate of the quantum key is improved.
The above embodiments are provided for illustrating the present application and not for limiting the present application, and various changes and modifications may be made by one skilled in the relevant art without departing from the scope of the present application, therefore, all equivalent technical solutions shall fall within the scope of the present disclosure.
Claims (9)
1. An apparatus for time division multiplexing, comprising:
an optical detection unit configured to receive time-division multiplexed light and detect, and convert the time-division multiplexed light into a time-division multiplexed electrical signal;
the clock distribution unit comprises a signal input port and two or more signal output ports, wherein the signal input ports are configured to receive the time division multiplexing electric signals, distribute the time division multiplexing electric signals to form first time division multiplexing electric signals, and output second time division multiplexing electric signals;
a programmable unit configured to issue a first control signal for detecting a synchronous electrical signal, a second control signal for detecting a classical electrical signal;
the first logic unit comprises two or more signal input ports, one signal output port has a logic operation function, is configured to receive the first time division multiplexing electric signal, the first control signal and process and send out the synchronous electric signal;
the second logic unit comprises two or more signal input ports, one signal output port has a logic operation function, is configured to receive the second time division multiplexing electric signal, and is used for processing the second control signal and sending out the classical electric signal.
2. The apparatus for demultiplexing according to claim 1, the clock distribution unit further being a clock distributor.
3. The apparatus for demultiplexing according to claim 1, the programmable unit further comprising:
a control chip configured to issue an operation instruction to the signal generating device or the delay device;
a signal generating device configured to receive an operation instruction of the control chip, and generate an electrical signal;
and the time delay device is configured to receive the operation instruction of the control chip, the electric signal generated by the signal generation device and perform time delay operation on the received electric signal according to the received operation instruction.
4. The apparatus for demultiplexing according to claim 1, the light detection unit further being a PN junction photodetector, or a PIN photodetector, or an Avalanche Photodiode (APD) detector, or a pull-through avalanche photodiode (RAPD) detector.
5. The apparatus of claim 1, the first logic unit or the second logic unit further being a logic chip.
6. The apparatus for demultiplexing according to claim 1, wherein the first logic unit or the second logic unit may be any one of an and circuit, an or gate nor gate, a nand gate, a nor gate, an exclusive or gate, and an exclusive or gate.
7. The apparatus of time division multiplexing of claim 1, the first logic unit or the second logic unit further being an and circuit.
8. The apparatus for demultiplexing as defined in claim 1, the signal characteristics of the first time-division multiplexed electrical signal and the second time-division multiplexed electrical signal being consistent with the signal characteristics of the time-division multiplexed electrical signal.
9. A method of time division multiplexing based on the apparatus of any of claims 1-8, the method of time division multiplexing comprising:
the light detection unit receives the time division multiplexing light and detects the time division multiplexing light, and the time division multiplexing light is converted into a time division multiplexing electric signal;
receiving the time division multiplexed electrical signal by the clock distribution unit and distributing to form a first time division multiplexed electrical signal and a second time division multiplexed electrical signal;
the programmable unit sends out a first control signal for detecting synchronous electric signals and a second control signal for detecting classical electric signals;
the first time division multiplexing electric signal and the first control signal are input into the first logic unit and are processed, and then synchronous electric signals are output;
the second time division multiplexing electric signal and the second control signal are input into the second logic unit, and after being processed, classical electric signals are output.
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| CN107276753A (en) * | 2017-06-27 | 2017-10-20 | 浙江九州量子信息技术股份有限公司 | The quantum key distribution system and method for a kind of channel multiplexing |
| CN211127818U (en) * | 2019-12-03 | 2020-07-28 | 国开启科量子技术(北京)有限公司 | Time division multiplexing device |
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| EP3018840A1 (en) * | 2014-11-10 | 2016-05-11 | Université de Genève | Apparatus and method for QKD quantum communication channel continuous synchronization and alignment |
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