A physical layer encryption system based on optical carrier driving chaos laser synchronization and a method thereof

Abstract

The application discloses a kind of physical layer encryption systems and method based on optical carrier drive chaos laser synchronization, including the sending end and receiving end connected using fiber link;The application is driven under the same optical carrier, and the local synchronization chaos laser is generated for phase encryption, and the information distortion / hiding effect of dispersion module is combined to realize physical layer encryption.Receiving end is decrypted by local synchronization chaos laser signal, and then the original optical signal is recovered by combining dispersion compensation, and then the transmitted information is recovered based on demodulation module.The application does not need third-party driving signal source, and does not occupy additional optical channel for transmission of driving signal, and the system is safe and reliable, with low operating cost and high channel utilization.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of chaotic laser signal and optical fiber communication technology, and relates to a physical layer encryption system based on optical carrier driven chaotic laser synchronization and a method thereof. BACKGROUND

[0002] In recent years, computer and communication technology has developed at an unprecedentedly fast pace. Optical fiber communication has outstanding advantages such as high speed, low loss and large capacity, and has become the main carrier and infrastructure of modern network information, and is the most important long-distance communication method today, which undertakes more than 90% of global communication services and involves various fields. However, the information security risk increases rapidly, and the events of eavesdropping on optical fibers are reported continuously, which has attracted people's high attention. On the one hand, the digital encryption system based on deterministic algorithm, such as the classic advanced encryption standard (AES), can still provide a certain security guarantee at present. However, due to the repeatability of the algorithm, with the emergence of super-high-speed computers such as quantum computers and the rise of artificial intelligence machine learning, the breaking risk is becoming more and more serious. Therefore, it is necessary to explore advanced physical encryption technology with non-deterministic characteristics to further improve the security of the communication system.

[0003] With the further development of technology, the hardware optical encryption based on the photon layer security has become a research hotspot for realizing high-speed secure optical communication. N. Jiang et al. of the University of Electronic Science and Technology of China studied a phase encryption technology based on third-party synchronous driving chaotic synchronization, which is inherently transparent to the modulation format and can be flexibly compatible with existing optical communication systems (A. Zhao, C. Xue, J. Tang and K. Qiu, Optics Letters 44(7), 1536-1539 (2019).). Z. Gao et al. of Guangdong University of Technology developed related technology, which encrypts the injected signal by dispersion and improves the privacy of the chaotic laser signal (see the literature: Z. Gao, Q. Wu, L. Liao, B. Su, X. Gao, S. Fu, Z. Li, Y. Wang and Y. Qin, Optics Express 30(17), 31209-31219 (2022)). However, in the above communication schemes, the transmission of the third-party driving signal is needed, and the driving signal is obvious and easy to be identified, which makes the information have the risk of being stolen and leaked. SUMMARY

[0004] The present application aims to overcome the defects of the prior art, and provides a physical layer encryption system and method based on optical carrier driving chaotic laser synchronization, which can obtain private synchronization chaotic laser for physical layer encryption without occupying additional channel resources and without third-party driving signals, and ensures communication security.

[0005] To solve the above technical problems, the present application adopts the following technical solutions.

[0006] The physical layer encryption system based on optical carrier driving chaotic laser synchronization comprises a sending end and a receiving end connected by an optical fiber link.

[0007] The sending end comprises a signal generating module and an encryption module connected in communication; the signal generating module comprises, in sequence and connected by optical paths or electricity, a first semiconductor laser, a polarization controller, data to be encrypted, and an intensity modulator; the encryption module comprises, in sequence and connected by optical paths or electricity, a first dispersion unit, a first phase modulator, a first optical fiber coupler, a second dispersion unit, a first optical circulator, a second semiconductor laser, a first photodetector, a first radio frequency amplifier, and a first optical fiber amplifier.

[0008] The signal generating module of the sending end emits an optical carrier for carrying the data to be encrypted, and the optical carrier passes through the polarization controller to adjust the polarization direction of the optical signal, and then is input to the intensity modulator; the intensity modulator modulates the data to be encrypted onto the optical carrier, emits an optical signal carrying the data to be encrypted, and enters the encryption module for encryption; in the encryption module, the first dispersion unit is connected with the output end of the intensity modulator, and the input end of the first phase modulator is connected with the first dispersion unit; the phase of the noise-like optical signal is disturbed to realize phase encryption, that is, the information is completely hidden through signal distortion caused by strong dispersion and phase encryption of the phase modulator.

[0009] The receiving end comprises a decryption module and a signal demodulation module connected in communication; the decryption module comprises, in sequence and connected by optical paths or electricity, a second optical fiber coupler, a third dispersion unit, a second optical circulator, a third semiconductor laser, a reverse photodetector, a second radio frequency amplifier, a second phase modulator, and a fourth dispersion unit; and the signal demodulation module comprises, in sequence and connected by optical paths or electricity, a second optical fiber amplifier, a second photodetector, and recovered information.

[0010] The receiving end decrypts the signal in the decryption module: the encrypted optical signal is divided into two by the second optical fiber coupler, one output end of which is connected with the third dispersion unit, and the other output end is connected with the input end of the second phase modulator; one port of the second optical circulator is connected with the third dispersion unit, and the two ports are connected with the third semiconductor laser; part of the received optical signal is injected into the third semiconductor laser through the above optical path, and the third dispersion unit performs optical scrambling on the injected optical signal; the chaotic laser signal generated by the third semiconductor laser is input from the two ports of the second optical circulator and output from the three ports to the reverse photoelectric detector for photoelectric conversion; the input end of the second radio frequency amplifier is connected with the output end of the reverse photoelectric detector to amplify the driving signal; the output end of the second radio frequency amplifier serves as the driving end of the second phase modulator to drive the second phase modulator to perform phase decryption; the phase-decrypted optical signal is sent into the fourth dispersion unit for dispersion compensation, and after the signal distortion caused by the first dispersion unit is eliminated, the signal is sent into the signal demodulation module; in the signal demodulation module, the optical signal with successful decryption is converted into electrical signal by the second optical fiber amplifier and the second photoelectric detector, and the transmitted information is recovered.

[0011] Further, a polarization controller is arranged in front of the first phase modulator to adjust the polarization state of the optical signal, so that the polarization direction of the optical signal meets the requirements of the first phase modulator.

[0012] Further, the first optical fiber coupler is a Y-type directional coupler, the input end of which is connected with the output end of the first phase modulator, one output end of which is connected with the input end of the second dispersion unit, and the other output end is connected with the input end of the first optical fiber amplifier, for dividing the phase-encrypted optical signal into two.

[0013] The one port of the first optical circulator is connected with the output end of the second dispersion unit, and the two ports are connected with the second semiconductor laser; the chaotic laser signal generated by the second semiconductor laser is input from the two ports of the first optical circulator and output from the three ports to the first photoelectric detector for photoelectric conversion; the input end of the first radio frequency amplifier is connected with the output end of the first photoelectric detector to amplify the driving signal; the output end of the first radio frequency amplifier serves as the driving end of the first phase modulator to drive the first phase modulator to perform phase encryption; another part of the phase-encrypted optical signal is transmitted to the receiving end through the first optical fiber amplifier and the optical fiber link.

[0014] Further, the optical fiber link includes a single-mode optical fiber and a dispersion compensation optical fiber matched with the dispersion value of the single-mode optical fiber.

[0015] Further, the first semiconductor laser has a center operating wavelength of 1550nm and a line width of 1.5MHz.

[0016] The first phase modulator and the second phase modulator have the same phase amplitude but opposite signs, and the first dispersion unit and the fourth dispersion unit have equal dispersion values but opposite signs.

[0017] The physical layer encryption method based on optical carrier driven chaotic laser synchronization of the present application is implemented by the physical layer encryption system based on optical carrier driven chaotic laser synchronization described above.

[0018] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0019] 1. The present application is provided with the second and third semiconductor lasers, which can realize synchronization under the driving of the carrier signal, and does not need an additional third-party driving signal source (such as a chaotic semiconductor laser, a constant amplitude random phase laser source and a spontaneous emission noise source), thereby saving cost.

[0020] 2. No additional channel is needed to transmit the driving signal, thereby saving channel resources.

[0021] 3. When used in cooperation with a wavelength division multiplexing system, the present application has better hiding effect and stronger privacy because the injected signal is one of the optical carriers.

[0022] 4. The security performance of the present application is based on the private synchronization of chaotic laser, and the distorted optical carrier signal has a higher bandwidth and is more sensitive to dispersion than general driving signals, thereby having better security.

[0023] 5. The present application can be applied to various optical modulation information modulation formats. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 FIG. 1 is a structural block diagram of a physical layer encryption system based on optical carrier driven chaotic laser synchronization according to an embodiment of the present application.

[0025] Figures 2(a)-(c) are time-domain waveform diagrams of an embodiment of the present application. Figure 2(a) is a time-domain waveform of a driving signal, Figure 2(b) is a time-domain waveform of a transmitter chaotic signal, and Figure 2(c) is a time-domain waveform of a receiver chaotic signal.

[0026] Figure 3(a) and 3(b) are correlation point diagrams of an embodiment of the present application. Figure 3(a) is a correlation point diagram of a second semiconductor laser and a third semiconductor laser, and Figure 3(b) is a correlation point diagram of a third semiconductor laser and an injection signal.

[0027] Figure 4(a) and 4(b) are waveform diagrams and eye diagrams of an original signal of an embodiment of the present application. Figure 4(a) is a waveform diagram of an original signal, and Figure 4(b) is an eye diagram of an original signal.

[0028] Figure 5(a) and 5(b) are waveform diagrams and eye diagrams of an encrypted original signal of an embodiment of the present application. Figure 5(a) is a waveform diagram of an encrypted original signal, and Figure 5(b) is an eye diagram of an encrypted original signal.

[0029] Figure 6(a) and 6(b) are waveform diagrams and eye diagrams of a decrypted signal of an embodiment of the present application. Figure 6(a) is a waveform diagram of a decrypted signal, and Figure 6(b) is an eye diagram of a decrypted signal.

[0030] Figure 7 is a curve diagram of an embodiment of the present application showing the influence of a modulation depth of a phase modulator on a system Q value.

[0031] Figure 8(a) is an eye diagram of a decrypted signal when legal decryption is performed at a modulation depth = 0.5, and Figure 8(b) is an eye diagram of a decrypted signal when illegal decryption is performed.

[0032] Figure 9(a) is an eye diagram of a decrypted signal when legal decryption is performed at a modulation depth = 0.8, and Figure 9(b) is an eye diagram of a decrypted signal when illegal decryption is performed.

[0033] Figure 10 is a curve diagram of an embodiment of the present application showing the influence of a dispersion mismatch value of a second dispersion unit and a third dispersion unit on a system Q value and a cross-correlation coefficient between a transmitter chaotic signal and a receiver chaotic signal.

[0034] The sending end 100 comprises a first semiconductor laser 101, a polarization controller 102, data to be encrypted 103, an intensity modulator 104, a first dispersion unit 105, a first phase modulator 106, a first fiber coupler 107, a second dispersion unit 108, a first optical circulator 109, a second semiconductor laser 110, a first photodetector 111, a first radio frequency amplifier 112, and a first fiber amplifier 113.

[0035] The receiving end 300 comprises a second fiber coupler 301, a third dispersion unit 302, a second optical circulator 303, a third semiconductor laser 304, a reverse photodetector 305, a second radio frequency amplifier 306, a second phase modulator 307, a fourth dispersion unit 308, a second fiber amplifier 309, a second photodetector 310, and recovered information 311. DETAILED DESCRIPTION

[0036] The physical layer encryption system and method based on optical carrier driven chaotic laser synchronization of the present application is based on the same optical carrier driving, generates local synchronous chaotic laser at both sides of communication, and uses the local synchronous chaotic laser for phase encryption, and combines the information distortion / hiding effect of the dispersion module to realize physical layer encryption. At the receiving end, the phase decryption is performed through the local synchronous chaotic laser signal, the original optical signal is recovered by combining the dispersion compensation, and then the transmitted information is recovered based on the demodulation module. The present application does not need a third party driving signal source, and does not occupy an extra optical channel for transmission of the driving signal, has the advantages of low cost and high channel utilization rate; the driving signal in the present application is the optical carrier itself, and combined with the WDM system, the security of the driving signal can be realized to a certain extent; the private synchronous chaotic laser is used for phase encryption to ensure the security of the system; the present application is compatible with various optical modulation formats, and is compatible with commercial communication networks.

[0037] The present application will be further described in detail below with reference to the accompanying drawings.

[0038] As shown in Figure 1 Fig. 1 is a structure schematic diagram of the physical layer encryption system based on optical carrier driven chaotic laser synchronization of the present application, which comprises a sending end 100 and a receiving end 300 connected by a fiber link 200.

[0039] The transmitting end 100 includes a signal generating module and an encryption module that are communicatively connected to each other; the signal generating module includes: a first semiconductor laser 101, a polarization controller 102, data to be encrypted 103, and an intensity modulator 104 that are optically or electrically connected in sequence; the encryption module includes: a first dispersion unit 105, a first phase modulator 106, a first fiber coupler 107, a second dispersion unit 108, a first optical circulator 109, a second semiconductor laser 110, a first photodetector 111, a first radio frequency amplifier 112, and a first fiber amplifier 113 that are optically or electrically connected in sequence.

[0040] The receiving end 300 includes a decryption module and a signal demodulation module that are communicatively connected to each other. The decryption module includes: a second fiber coupler 301, a third dispersion unit 302, a second optical circulator 303, a third semiconductor laser 304, a reverse photodetector 305, a second radio frequency amplifier 306, a second phase modulator 307, and a fourth dispersion unit 308, which are optically or electrically connected in sequence. The signal demodulation module includes: a second fiber amplifier 309, a second photodetector 310, and recovered information 311, which are optically or electrically connected in sequence.

[0041] Depend on Figure 1 It can be seen that in the signal generating module of the transmitting end 100, the first semiconductor laser 101 emits an optical carrier for carrying the data to be encrypted. The polarization direction of the optical carrier is adjusted by the polarization controller 102, and then input into the intensity modulator 104. The intensity modulator 104 modulates the data to be encrypted 103 onto the optical carrier, thereby emitting an optical signal carrying the data to be encrypted. The optical signal enters the encryption module for encryption.

[0042] In the encryption module, the first dispersion unit 105 is connected with the output end of the intensity modulator 104, under the action of strong dispersion, the optical signal is seriously distorted to form a noise-like signal, and the information cannot be directly read through the signal; the input end of the first phase modulator 106 is connected with the first dispersion unit 105, and the phase of the noise-like optical signal is disturbed to realize phase encryption, that is, through the signal distortion caused by strong dispersion and the phase encryption of the phase modulator, the information is completely hidden. Since the phase modulator is a polarization-sensitive device, it only acts on the polarized light in a specific direction, so a polarization controller 102 is arranged in front of the first phase modulator 106, and the polarization state of the optical signal is adjusted through the polarization controller 102 to make the polarization direction of the optical signal meet the requirements of the first phase modulator 106. The first fiber coupler 107 is a Y-type directional coupler, the input end of which is connected with the output end of the first phase modulator 106, one output end of which is connected with the input end of the second dispersion unit 108, and the other output end is connected with the input end of the first fiber amplifier 113, which is used to divide the phase-encrypted optical signal into two parts. One port of the first optical circulator 109 is connected with the output end of the second dispersion unit 108, and the other port is connected with the second semiconductor laser 110. A part of the phase-encrypted optical signal is injected into the second semiconductor laser 110 through the above optical path to make it output chaotic laser signal. The second dispersion unit 108 performs optical scrambling on the injected optical signal, which prevents the eavesdropper from generating a synchronous chaotic laser signal by using the same injection system to decrypt the phase encryption and improves the privacy of the injected optical signal. The chaotic laser signal generated by the second semiconductor laser 110 is input from the two ports of the first optical circulator 109 and output from the three ports to the first photodetector 111 for photoelectric conversion. The input end of the first radio frequency amplifier 112 is connected with the output end of the first photodetector 111 to amplify the driving signal in radio frequency; the output end of the first radio frequency amplifier 112 is used as the driving end of the first phase modulator 106 to drive the first phase modulator 106 to perform phase encryption; the other part of the phase-encrypted optical signal is transmitted to the receiving end 300 through the first fiber amplifier 113 and the optical fiber link 200.

[0043] The encrypted signal is transmitted in the transmission link 200 composed of a single-mode optical fiber and a dispersion compensation optical fiber matched with the dispersion value of the single-mode optical fiber.

[0044] At the receiving end 300, the encrypted signal enters the decryption module for decryption: the second optical fiber coupler 301 is a Y-shaped directional coupler, the encrypted optical signal is divided into two through the second optical fiber coupler 301, one output end is connected with the input end of the third dispersion unit 302, and the other output end is connected with the input end of the second phase modulator 307. One port of the second optical circulator 303 is connected with the output end of the third dispersion unit 302, and the other port is connected with the third semiconductor laser 304. Part of the received optical signal is injected into the third semiconductor laser 304 through the above optical path, the third dispersion unit 302 performs optical scrambling on the injected optical signal, which prevents the eavesdropper from generating a synchronous chaotic laser signal for phase decryption by using the same injection system, and improves the privacy of the injected optical signal. The chaotic laser signal generated by the third semiconductor laser 304 is input from the two ports of the second optical circulator 303 and output from the three ports to the reverse photoelectric detector 305 for photoelectric conversion. The input end of the second radio frequency amplifier 306 is connected with the output end of the reverse photoelectric detector 305, and the radio frequency of the driving signal is amplified; the output end of the second radio frequency amplifier 306 is used as the driving end of the second phase modulator 307, and the second phase modulator 307 is driven to perform phase decryption; the phase-decrypted optical signal is sent to the fourth dispersion unit 308 for dispersion compensation, and after the signal distortion caused by the first dispersion unit 105 is eliminated, the signal is sent to the signal demodulation module.

[0045] In the signal demodulation module, the optical signal with successful decryption is converted into an electrical signal by the second optical fiber amplifier 309 and the second photoelectric detector 310, and the transmitted information is recovered.

[0046] In the embodiment system of the application, the first optical amplifier 113 and the second optical amplifier 309 are both erbium-doped fiber amplifiers, which are used to compensate the power loss of the optical signal. The phase amplitudes applied by the first phase modulator 106 and the second phase modulator 307 are the same, but the signs are opposite. The dispersion values of the first dispersion unit 105 and the fourth dispersion unit 308 are equal, but the signs are opposite. The dispersion values of the second dispersion unit 108 and the third dispersion unit 302 are dynamically adjustable, which improves the privacy. The dispersion units can be constructed by using dispersion compensation fiber or chirped fiber grating.

[0047] The application is simulated on the professional software Matlab, and the encrypted data is NRZ code with a bit rate of 40 Gb / s. Table 1 is the parameters set in the system simulation.

[0048] Table 1.

[0049]

[0050]

[0051] Figure 2(a) shows the time domain waveform of the driving signal, Figure 2(b) shows the time domain waveform of the chaotic signal from the transmitter, and Figure 2(c) shows the time domain waveform of the chaotic signal from the receiver. Figure 3(a) shows the correlation diagram of the second semiconductor laser 110 and the third semiconductor laser 304, and Figure 3(b) shows the correlation diagram of the third semiconductor laser 304 and the injected signal. As can be seen from Figures 2(b), 2(c), and 3(a), the time domain waveforms of the chaotic signals output by the second semiconductor laser 110 and the third semiconductor laser 304 are very similar, and the distribution of the points in the correlation diagram approximates a straight line, with a corresponding cross-correlation coefficient of 0.99. This indicates that the driving signals of the first phase modulator 106 and the second phase modulator 307 are almost completely synchronized, and high-quality chaotic synchronization ensures successful decryption of the information. Figure 3(b) shows that the distribution of the points in the correlation diagram of the chaotic signal output by the third semiconductor laser 304 and its injected signal is chaotic, with a corresponding cross-correlation coefficient of only 0.18, so it can be considered that the two signals are uncorrelated. For the eavesdropper, the low correlation between them makes it impossible to recover the driving signal of the phase modulator, ensuring the security of encryption and decryption. The formula for calculating the mutual correlation coefficient is:

[0052]

[0053] Here, I1 and I2 represent two discrete time series, the operator <·> represents the average of the discrete time series, and Δt is the signal delay. To quantify synchronization quality, the maximum absolute value of the CCF, or the cross-correlation coefficient, is typically used to represent the degree of cross-correlation between chaotic signals. The time corresponding to this value is the synchronization delay between the signals. A larger cross-correlation coefficient indicates a higher correlation between the two time series. Specifically, the closer the cross-correlation coefficient is to 1, the better the synchronization quality; the closer it is to 0, the worse the synchronization quality. In summary, the present invention improves the confidentiality of physical encryption and decryption, thereby further enhancing system security.

[0054] Figure 4(a) and Figure 4(b) are the waveform and eye diagram of the original signal respectively. Figure 5(a) and Figure 5(b) are the waveform and eye diagram of the encrypted original signal respectively. Figure 6(a) and Figure 6(b) are the waveform and eye diagram of the decrypted signal respectively. Figure 4(a) 、 4(b) As can be seen in Figures 5(a), 5(b), 6(a), and 6(b), the amplitude of the optical signal encrypted by transmitter 100 is distorted, and both the amplitude and phase of the information are encrypted. The eye diagram in Figure 5(b) is completely closed, completely hiding the information. Figures 6(a) and 6(b) show that after the signal is correctly decrypted, the waveforms are very similar to the original signal and have a clear eye opening.

[0055] Figure 7Fig. 2 is a diagram showing the influence of the modulation depth of the phase modulator on the Q value of the system. The Q value is calculated according to the formula:

[0056] Q = ( <P1> - <P2> ) / ( σ1 - σ0 ) (2)

[0057] where <P1> and <P2> are the average power of the received bit "1" and the average power of the received bit "0", respectively, and σ1 and σ0 are the corresponding standard deviations. The corresponding bit error rate can be calculated by the Q factor. The greater the Q value, the lower the corresponding bit error rate, and the better the performance of the system. For example, when Q = 6, the bit error rate of the system is about 10 －9 -6, and when Q = 7, the bit error rate of the system is about 10 －12 . Figure 7 The dotted line connected by squares represents the change of the Q value in the case of legal decryption, and the dotted line connected by circles represents the change of the Q value in the case of dispersion compensation only (illegal decryption). It can be seen from Figure 7 that, as the modulation depth increases, the Q value gradually decreases, but the Q value in the case of legal decryption is always much greater than the Q value in the case of illegal decryption.

[0058] Fig. 8(a) and Fig. 8(b) are eye diagrams of the decrypted signals obtained in the cases of legal decryption and illegal decryption, respectively, when the modulation depth is 0.5. Fig. 9(a) and Fig. 9(b) are eye diagrams of the decrypted signals obtained in the cases of legal decryption and illegal decryption, respectively, when the modulation depth is 0.8. The decrypted signal obtained in the case of legal decryption has a clear eye opening, and the eye diagram of the decrypted signal obtained in the case of illegal decryption is completely closed; that is, the legal decryption can successfully obtain the transmitted information, while the illegal decryption cannot obtain the transmitted information.

[0059] From Figure 7 , 8(a) , 8(b), 9(a), 9(b), it can be seen that, by selecting a suitable modulation depth, even if the eavesdropper knows the dispersion values of the first dispersion unit 105 and the fourth dispersion unit 308 to perform dispersion compensation, the eavesdropper cannot successfully decrypt the signal to recover the original information, thus ensuring the security of encryption and decryption. Even if the eavesdropper knows the structure of the present application, the decryption process of the eavesdropper cannot be synchronized with the encryption signal, and the eavesdropper cannot correctly decrypt, thus improving the security of signal transmission.

[0060] Figure 10The influence of dispersion mismatch on the system Q value and the correlation coefficient between the transmitter and receiver chaotic signals for the second dispersion unit 108 and the third dispersion unit 302 is shown in the graph. The graph shows the variation trend of the legal decryption Q value and the correlation coefficient. The results show that as the dispersion mismatch increases, the Q value and the correlation coefficient gradually decrease, which makes the decryption performance worse, thus leading to the gradual increase of the system bit error rate. However, the receiver can realize signal decryption within a certain range of dispersion mismatch, i.e., the system has a certain robustness.

Claims

1. A physical layer encryption system based on optical carrier driven chaotic laser synchronization, characterized in that, The application relates to a sending terminal (100) and a receiving terminal (300) connected through an optical fiber link (200). The sending terminal (100) comprises a signal generating module and an encryption module in communication connection; the signal generating module comprises a first semiconductor laser (101), a polarization controller (102), encrypted data (103) and an intensity modulator (104) in optical or electrical connection; the encryption module comprises a first dispersion unit (105), a first phase modulator (106), a first optical fiber coupler (107), a second dispersion unit (108), a first optical circulator (109), a second semiconductor laser (110), a first photodetector (111), a first radio frequency amplifier (112) and a first optical fiber amplifier (113) in optical or electrical connection. The signal generating module of the sending terminal (100) is characterized in that the first semiconductor laser (101) emits an optical carrier for carrying the encrypted data; the optical carrier passes through the polarization controller (102) to adjust the polarization direction of the optical signal, and then is input into the intensity modulator (104); the intensity modulator (104) modulates the encrypted data (103) onto the optical carrier, emits the optical signal carrying the encrypted data and enters the encryption module for encryption; in the encryption module, the first dispersion unit (105) is connected with the output end of the intensity modulator (104), the input end of the first phase modulator (106) is connected with the first dispersion unit (105), the phase of the noise-like optical signal is disturbed to realize phase encryption, that is, the information is completely hidden through signal distortion caused by strong dispersion and phase encryption of the phase modulator; The receiving terminal (300) comprises a decryption module and a signal demodulation module in communication connection; the decryption module comprises a second optical fiber coupler (301), a third dispersion unit (302), a second optical circulator (303), a third semiconductor laser (304), a reverse photodetector (305), a second radio frequency amplifier (306), a second phase modulator (307) and a fourth dispersion unit (308) in optical or electrical connection; and the signal demodulation module comprises a second optical fiber amplifier (309), a second photodetector (310) and recovered information (311) in optical or electrical connection. The receiving end (300) carries out signal decryption in the decryption module: the encrypted optical signal is divided into two by the second optical fiber coupler (301), one output end of which is connected with the third dispersion unit (302), and the other output end is connected with the input end of the second phase modulator (307); one port of the second optical circulator (303) is connected with the third dispersion unit (302), and the two ports are connected with the third semiconductor laser (304); part of the received optical signal is injected into the third semiconductor laser (304) through the above optical path, and the third dispersion unit (302) carries out optical scrambling on the injected optical signal; the chaotic laser signal generated by the third semiconductor laser (304) is input from the two ports of the second optical circulator (303) and output from the three ports to the reverse photoelectric detector (305) for photoelectric conversion; the input end of the second radio frequency amplifier (306) is connected with the output end of the reverse photoelectric detector (305) to amplify the driving signal in radio frequency; the output end of the second radio frequency amplifier (306) is used as the driving end of the second phase modulator (307) to drive the second phase modulator (307) to carry out phase decryption; the phase-decrypted optical signal is sent into the fourth dispersion unit (308) for dispersion compensation, and after the signal distortion caused by the first dispersion unit (105) is eliminated, the signal is sent into the signal demodulation module. In the signal demodulation module, the optical signal with successful decryption is converted into electrical signal by the second optical fiber amplifier (309) and the second photoelectric detector (310), and the transmitted information is recovered.

2. The physical layer encryption system based on optical carrier driving chaos laser synchronization according to claim 1, characterized in that, A polarization controller (102) is arranged in front of the first phase modulator (106) to adjust the polarization state of the optical signal, so that the polarization direction of the optical signal meets the requirements of the first phase modulator (106).

3. The physical layer encryption system based on optical carrier driving chaos laser synchronization according to claim 1, characterized in that, The first optical fiber coupler (107) is a Y-type directional coupler, the input end of which is connected with the output end of the first phase modulator (106), one output end of which is connected with the input end of the second dispersion unit (108), and the other output end is connected with the input end of the first optical fiber amplifier (113), which is used to divide the phase-encrypted optical signal into two.

4. The physical layer encryption system based on optical carrier driving chaos laser synchronization according to claim 1, characterized in that, One port of the first optical circulator (109) is connected with the output end of the second dispersion unit (108), and the two ports are connected with the second semiconductor laser (110); the chaotic laser signal generated by the second semiconductor laser (110) is input from the two ports of the first optical circulator (109) and output from the three ports to the first photoelectric detector (111) for photoelectric conversion; the input end of the first radio frequency amplifier (112) is connected with the output end of the first photoelectric detector (111) to amplify the driving signal in radio frequency; the output end of the first radio frequency amplifier (112) is used as the driving end of the first phase modulator (106) to drive the first phase modulator (106) to carry out phase encryption; another part of the phase-encrypted optical signal is transmitted to the receiving end (300) through the first optical fiber amplifier (113) and the optical fiber link (200).

5. The physical layer encryption system based on optical carrier driving chaos laser synchronization according to claim 1, characterized in that, The optical fiber link (200) comprises a single-mode optical fiber and a dispersion compensation optical fiber matched with the dispersion value of the single-mode optical fiber.

6. The physical layer encryption system based on optical carrier driving chaos laser synchronization according to claim 1, characterized in that, The first semiconductor laser (101) has a center operating wavelength of 1550 nm and a line width of 1.5 MHz.

7. The physical layer encryption system based on optical carrier driving chaos laser synchronization according to claim 1, characterized in that, The first optical fiber amplifier (113) and the second optical fiber amplifier (309) are both erbium-doped optical fiber amplifiers.

8. The physical layer encryption system based on optical carrier driving chaos laser synchronization according to claim 1, characterized in that, The first phase modulator (106) and the second phase modulator (307) have the same phase amplitude but opposite signs; the first dispersion unit (105) and the fourth dispersion unit (308) have equal dispersion values but opposite signs.

9. The physical layer encryption system based on optical carrier driving chaos laser synchronization according to claim 1, characterized in that, The second dispersion unit (108) and the third dispersion unit (302) have dynamically adjustable dispersion values and use dispersion compensation optical fiber or a chirped fiber grating.

10. A physical layer encryption method based on optical carrier driven chaotic laser synchronization, characterized in that, The implementation of the physical layer encryption system based on the optical carrier driven chaotic laser synchronization according to any one of claims 1 to 9 is performed, wherein the sending end is driven based on the same optical carrier, local synchronization chaotic laser is generated at both ends of communication, and the local synchronization chaotic laser is used for phase encryption; meanwhile, the information distortion / hiding effect of the dispersion module is combined to realize physical layer encryption; the receiving end performs phase decryption through the local synchronization chaotic laser signal, combines dispersion compensation to recover the original optical signal, and finally recovers the transmitted information based on the demodulation module.

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