Optical communication system and method based on amplitude-phase dual-dimensional chaotic encryption

Abstract

The present invention discloses an optical communication system and method based on amplitude-phase dual-dimensional chaotic encryption. In this system, light from a first laser is coupled with an optical signal through a Mach-Zehnder modulator and an optical coupler, and then split into two beams. One beam passes through a delay line, etc., and then enters the Mach-Zehnder modulator; the other beam is injected into a phase modulator. Light from a fifth laser is split into two beams by a third optical coupler, one of which passes through a reflector. The other beam is split into two beams by a fourth optical coupler, one of which is used for channel transmission; the other beam passes through a first circulator, etc., and then enters the first phase modulator. After channel transmission, the light passes through the circulator, etc., and then enters the phase modulator. The other beam passes through the phase modulator and optical coupler, splitting into two beams. One beam is connected to an optical mixer; the other beam passes through a second delay line, etc., and then enters a second Mach-Zehnder modulator. Light from a second laser passes through the second Mach-Zehnder modulator and then enters the optical mixer. Decryption is achieved through coherent detection.

Description

Technical Field

[0001] The present invention belongs to the field of optical information technology, and in particular relates to an optical communication system and method based on amplitude-phase dual-dimensional chaotic encryption. Background Art

[0002] Chaotic signals, due to their unique characteristics of unpredictability, noise-like nature, wide bandwidth, and extreme sensitivity to initial values, have shown significant advantages in the field of high-speed, long-distance secure communications. Moreover, chaotic encryption communication of plaintext signals is based on the physical layer, and its security is superior to traditional secure communication systems based on application-layer digital encryption.

[0003] However, existing optical chaotic secure communication systems still suffer from weak confidentiality and low information transmission efficiency. To address this issue, the present invention proposes an optical communication system and method based on amplitude-phase dual-dimensional chaotic encryption. This method improves transmission rates and expands the key space while enabling plaintext information to participate in chaotic signal generation and encrypting it in both amplitude and phase dimensions, effectively enhancing the security and reliability of the communication system. Summary of the Invention

[0004] In response to the above-mentioned status quo of the existing technology, the present invention improves the complexity and transmission rate of chaotic signals and effectively improves the security and reliability of optical chaotic communication systems by adopting the method of chaotic encryption of plaintext signals in both amplitude and phase dimensions. By adopting the method of electro-optical delay intensity feedback and all-optical feedback combined with optical injection, an optical communication system and method based on amplitude and phase dual-dimensional chaotic encryption are designed.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] An optical communication system based on amplitude-phase dual-dimensional chaotic encryption includes a transmitter and a receiver, which are connected via an optical fiber link. Specifically,

[0007] At the transmitter, the binary plaintext signal is converted into an electrical signal by a mapper and then injected into an in-phase quadrature modulator (IQM). A third optical signal, emitted by a third continuous-wave laser, enters the IQM, where it is modulated into an optical signal to produce the plaintext signal used for optical chaos encryption. The optical signal then passes through a third variable optical attenuator and enters the first optical attenuator.

[0008] A first optical signal emitted by a first continuous wave laser passes through a first Mach-Zehnder modulator and enters a first optical coupler, where it is split into two optical signals, namely a first optical signal and a second optical signal. The first optical signal is coupled with a plaintext signal and then enters a first phase modulator. The second optical signal is coupled with the plaintext signal and then passes through a first delay line, a first variable optical attenuator, a first photodetector, and a first radio frequency amplifier in sequence before entering the first Mach-Zehnder modulator.

[0009] The fifth continuous wave laser is split into two beams after passing through the third optical coupler. One beam is directed to the reflector (M), and the other beam is split into two optical signals through the fourth optical coupler. The first beam enters the first input port of the wavelength division multiplexer (WDM). The second beam passes through the first circulator and enters the sixth continuous wave laser. Then, it returns to the first circulator and then enters the first phase modulator through the third photodetector. The output port of the first phase modulator is connected to the second input port of the wavelength division multiplexer. The output port of the wavelength division multiplexer is connected to the receiving end through an optical fiber.

[0010] At the receiving end, the signal transmitted through the optical fiber link is split into two beams by the wavelength division multiplexer. One beam passes through the second circulator and enters the seventh continuous wave laser, then returns to the second circulator, and then passes through the fourth photodetector and enters the second phase modulator. The other beam enters the second phase modulator;

[0011] After phase decryption by the second phase modulator, the optical signal is split into two beams through a second optical coupler. One beam enters the first input port of a 90-degree optical mixer (hybrid), and the other beam passes through a second delay line, a second variable photoelectric attenuator, a second photodetector, and a second radio frequency amplifier before entering a second Mach-Zehnder modulator. The optical signal emitted by the second continuous-wave laser passes through the second Mach-Zehnder modulator and enters the second input port of the 90-degree optical mixer.

[0012] Intensity decryption is achieved through subtraction of a 90-degree optical mixer. The 90-degree optical mixer is connected to the first input port of the coherent receiver, and the fourth continuous wave laser is connected to the second input port of the coherent receiver. The electrical signal is obtained through the coherent receiver, and then the original binary plaintext information is restored through the inverse mapper.

[0013] In the present invention, the transmitter includes three modules: signal modulation, intensity chaos encryption, and phase chaos encryption. In the signal modulation module, a binary plaintext signal is converted into an electrical signal by a mapper and injected into an in-phase quadrature modulator. A third optical signal emitted by a third continuous-wave laser enters the in-phase quadrature modulator, where it is modulated into an optical signal, thereby obtaining a plaintext signal for optical chaos encryption. The optical signal passes through a third variable optical attenuator and enters a first optical coupler, where it is split into two beams. One beam participates in the intensity chaos process, and the other beam enters a first phase modulator. In the intensity chaos module, a first optical signal emitted by a first continuous-wave laser passes through a first Mach-Zehnder modulator and enters a first optical coupler, where it is split into two beams. One beam is coupled with the optical signal and enters the first phase modulator. The other beam is coupled with the plaintext information and passes through a first delay line, a first variable optical attenuator, a first photodetector, and a first radio frequency amplifier before entering the radio frequency drive port of the first Mach-Zehnder modulator. In the phase chaos encryption module, the fifth optical signal emitted by the fifth continuous wave laser is first split into two beams by the third coupler. One beam is reflected back to the fifth continuous wave laser by a reflector. The other beam is also split into two beams by the fourth optical coupler. One beam enters the wavelength division multiplexer (WDM). The other beam passes through the first circulator and is first injected into the sixth continuous wave laser. It then passes through the first circulator and the third photodetector before entering the RF drive port of the first phase modulator. Finally, the signal encrypted by the first phase modulator enters the WDM, whose output port is connected to the receiving end via optical fiber.

[0014] The receiving end adopts an open-loop structure symmetrical to the transmitting end, primarily comprising a phase chaos decryption module, an intensity chaos decryption module, and a signal demodulation module. In the phase chaos decryption module, the multiplexed signal transmitted via the optical fiber link is split into two beams by a wavelength division multiplexer. One beam passes through a second circulator and is first injected into a seventh continuous-wave laser. It then passes through the second circulator and the fourth photodetector before entering the second phase modulator. The other beam enters the second phase modulator. In the intensity decryption module, the phase-decrypted optical signal is split into two beams by a second optical coupler. One beam enters an optical mixer, while the other beam passes through a second delay line, a second variable optical attenuator, a second photodetector, and a second RF amplifier before entering the RF drive port of the second Mach-Zehnder modulator. The optical signal generated by the second continuous-wave laser passes through the second Mach-Zehnder modulator, where it is modulated with the phase decryption signal to generate an intensity chaos signal, which then enters the second input port of the optical mixer. The phase decryption signal and the intensity chaos signal are subtracted by the optical mixer to achieve intensity decryption. In the signal demodulation module, the intensity-decrypted signal and the optical signal generated by the fourth continuous-wave laser are connected to a coherent receiver and can be restored to an electrical signal. Finally, the original binary signal is restored through an inverse mapper.

[0015] As a preferred solution, according to the binary plaintext information to be transmitted, 16QAM optical modulation is used to modulate the signal into an optical QAM signal for optical chaotic encryption and transmission; and the optical plaintext signal is involved in the generation process of the intensity chaotic carrier, which also means that the plaintext information is hidden.

[0016] As a preferred embodiment, the parameters of the corresponding devices between the transmitting end and the receiving end are the same, that is: the parameters of the first laser and the second laser are the same; the parameters of the third laser and the fourth laser are the same; the parameters of the sixth laser and the seventh laser are the same; the parameters of the first Mach-Zehnder modulator and the second Mach-Zehnder modulator are the same; the parameters of the first optical coupler, the second optical coupler, the third optical coupler and the fourth optical coupler are the same, such as the coupling coefficients are all 0.5; the parameters of the first delay line and the second delay line are the same; the parameters of the first variable optical attenuator and the second variable optical attenuator are the same; the parameters of the first photodetector and the second photodetector are the same; the parameters of the third photodetector and the fourth photodetector are the same; the parameters of the first radio frequency amplifier and the second radio frequency amplifier are the same; and the parameters of the first phase modulator and the second phase modulator are the same.

[0017] In the present invention, the intensity chaos encryption module at the transmitting end generates a first optical chaotic signal through electro-optical delay feedback, and the optical text signal is coupled into the electro-optical delay feedback loop to participate in the generation of the first optical chaotic signal, thereby hiding the optical text signal. The phase chaos encryption module generates a driving chaotic signal through all-optical feedback, and injects the driving chaotic signal into the laser again to generate a more complex transmitting chaotic signal, that is, the second optical chaotic signal. The intensity encryption signal is phase-encrypted through a first phase modulator. It is then wavelength-division multiplexed with the driving chaotic signal to enter the optical fiber transmission link. At the receiving end, a symmetrical structure is used to generate a synchronized chaotic signal with the transmitting end. The received encrypted signal is phase-decrypted to induce the generation of a synchronized intensity chaotic signal, and preliminary decryption is achieved through an optical mixer. Coherent detection is then performed to restore the electrical signal, and finally, inverse mapping is used to restore the binary plaintext information.

[0018] As a preferred solution, the coupling coefficients of all couplers are 0.5.

[0019] As a preferred solution, the signal transmission rate of the communication system is 40Gb / s.

[0020] As a preferred solution, the receiving end recovers the binary plaintext information through an optical mixer, a coherent receiver and a 16QAM demapper.

[0021] The present invention also discloses an optical communication method based on amplitude-phase dual-dimensional chaotic encryption. Based on the above system, the method comprises the following specific steps:

[0022] At the transmitter, the binary plaintext signal is mapped to an electrical signal, which is then injected into an in-phase quadrature modulator. The optical signal emitted by the third continuous-wave laser undergoes in-phase quadrature modulation to generate the plaintext signal used for optical chaotic encryption. This signal then enters the first optical coupler through the third variable optical attenuator to participate in the generation of the intensity chaotic signal. The optical signal emitted by the first continuous-wave laser undergoes electro-optical delay feedback to generate an intensity chaotic signal, thereby achieving intensity encryption of the plaintext signal. The optical signal emitted by the fifth continuous-wave laser undergoes all-optical feedback to generate a driving chaotic signal, which is then injected into the sixth continuous-wave laser to generate a phase chaotic signal. The intensity-encrypted signal is then phase-encrypted again using the first phase modulator, achieving encryption of the plaintext signal in both intensity and phase dimensions. During this process, the plaintext information participates in the generation of the optical intensity chaos, increasing the complexity of the chaotic signal. The open-loop structure of the electro-optical delay feedback loop makes the system highly robust. The device parameters in each module further expand the key space, improving the security of the chaotic communication system.

[0023] At the receiving end, a structure symmetrical to that of the transmitting end is used to implement chaotic decryption. A phase chaotic signal synchronized with the transmitting end is first generated, and phase decryption is performed using a second phase modulator. A second optical coupler then splits the signal into two beams, one for intensity decryption and the other to induce intensity chaos. A 90-degree optical mixer then performs a phase subtraction operation to achieve intensity decryption. Signal demodulation then proceeds, with coherent detection performed between the intensity-decrypted signal and the optical signal generated by a fourth continuous-wave laser. Finally, inverse mapping is used to recover the original binary plaintext signal.

[0024] At the transmitting end of the present invention, the optical signals emitted by the first, fifth, and sixth continuous-wave lasers undergo electro-optical time-delay feedback and all-optical feedback combined with optical injection to generate chaotic signals for intensity encryption and phase encryption, respectively. The optical signal emitted by the third continuous-wave laser is passed through an in-phase quadrature modulator to generate a light signal for optical chaos encryption. This signal, in turn, participates in the intensity chaos generation process through a third variable optical attenuator and a first optical coupler, thus achieving intensity chaos encryption. The phase chaos signal is converted into an electrical signal by a third photodetector, and the intensity-encrypted signal is phase-modulated by the first phase modulator, achieving phase encryption.

[0025] The receiving end of the present invention uses a structure symmetrical to that of the transmitting end to implement chaotic decryption. A seventh continuous-wave laser generates a phase-chaotic signal synchronized with the transmitting end, and a second phase modulator performs phase decryption on the encrypted signal. The phase-decrypted optical signal is split into two beams by a second optical coupler: one for intensity decryption and the other for generating an intensity-chaotic signal synchronized with the transmitting end. This signal is then combined with the phase-decrypted signal through a 90-degree optical mixer to perform intensity decryption. The intensity-decrypted signal and the optical signal generated by the fourth continuous-wave laser are then coherently detected to recover the electrical signal. Finally, inverse mapping is performed to restore the original binary signal.

[0026] Preferably, the signal transmission rate is set to 40 Gb / s.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention proposes an optical communication system and method based on amplitude-phase dual-dimensional chaotic encryption. At the transmitter, binary plaintext information is first modulated into an optical signal using an in-phase quadrature modulator. Chaos is generated using a Mach-Zehnder modulator, and the optical signal is then coupled to the intensity chaotic signal generation process via a coupler to achieve intensity encryption. By incorporating the plaintext information into the chaotic generation process, the complexity of the chaotic signal is increased while effectively hiding the plaintext information, further enhancing the security of information transmission and effectively preventing signal interception. Phase encryption is then performed, first using all-optical feedback to generate a chaotic signal, and then injecting light into the generated chaotic signal to generate a new chaotic signal. This method enhances the bandwidth of the chaotic carrier, overcoming the information transmission rate limitations caused by the limited bandwidth of the chaotic carrier. Finally, the optical signal is converted into an electrical signal using a photodetector, and phase modulation is performed using a phase modulator to achieve phase encryption. This further expands the key space, effectively preventing brute-force attacks by illegal eavesdroppers, and further improving the security and reliability of the communication system. Furthermore, the present invention utilizes an open-loop symmetrical structure to achieve chaotic synchronization, which makes the communication system highly robust. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] Figure 1 This is a schematic diagram of the architecture of an optical communication system based on amplitude-phase dual-dimensional chaotic encryption according to a preferred embodiment of the present invention.

[0031] Figure 2 This is a constellation diagram of a 16QAM optical signal input at the transmitting end of an optical communication system based on amplitude-phase dual-dimensional chaotic encryption in a preferred embodiment of the present invention.

[0032] Figure 3This is a constellation diagram of a 16QAM optical signal decrypted in an optical communication system based on amplitude-phase dual-dimensional chaotic encryption in a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0033] To more clearly illustrate the embodiments of the present invention, specific embodiments of the present invention will be described below with reference to the accompanying drawings. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings and other embodiments can be obtained based on these drawings without inventive effort.

[0034] like Figure 1 As shown, this embodiment provides an optical communication system based on amplitude-phase dual-dimensional chaotic encryption, including a transmitting end and a receiving end, wherein:

[0035] The transmitting end components include a first continuous wave laser 1-1, a third continuous wave laser 1-3, a fifth continuous wave laser 1-5, a sixth continuous wave laser 1-6, a first Mach-Zehnder modulator 2-1, a first optical coupler 3-1, a third optical coupler 3-3, a fourth optical coupler 3-4, a first delay line 4-1, a first variable attenuator 5-1, a third variable attenuator 5-3, a first photodetector 6-1, a third photodetector 6-3, a first radio frequency amplifier 7-1, a first phase modulator 8-1, a first circulator 9-1, an in-phase quadrature modulator IQM, a reflector M, and a wavelength division multiplexer WDM;

[0036] The receiving end components include a second continuous wave laser 1-2, a fourth continuous wave laser 1-4, a seventh continuous wave laser 1-7, a second Mach-Zehnder modulator 2-2, a second optical coupler 3-2, a second delay line 4-2, a second variable attenuator 5-2, a second photodetector 6-2, a fourth photodetector 6-4, a second RF amplifier 7-2, a second phase modulator 8-2, a second circulator 9-2, a 90-degree optical mixer, a coherent receiver, and a wavelength division multiplexer.

[0037] The transmitting end and the receiving end are connected through a standard single-mode optical fiber 10 , an erbium-doped optical fiber amplifier 11 and a dispersion-compensating optical fiber 12 .

[0038] The specific connection method of the above components is as follows:

[0039] At the transmitting end, the first continuous wave laser 1-1 is connected to the input port of the first Mach-Zehnder modulator 2-1, the output port of the first Mach-Zehnder modulator 2-1 is connected to the first input port of the first optical coupler 3-1, the first output port of the first optical coupler 3-1 is connected to the input port of the first phase modulator 8-1, the second output port of the first optical coupler 3-1 is connected to the first port of the first delay line 4-1, the second port of the first delay line 4-1 is connected to the first port of the first variable optical attenuator 5-1, the second port of the first variable optical attenuator 5-1 is connected to the input port of the first photodetector 6-1, the output port of the first photodetector 6-1 is connected to the input port of the first radio frequency amplifier 7-1, and the output port of the first radio frequency amplifier 7-1 is connected to the radio frequency drive port of the first Mach-Zehnder modulator 2-1.

[0040] The 16QAM mapper is connected to the first input port of the in-phase quadrature modulator, the third continuous wave laser 1-3 is connected to the second input port of the in-phase quadrature modulator, the output port of the in-phase quadrature modulator is connected to the first port of the third variable optical attenuator 5-3, and the second port of the third variable optical attenuator 5-3 is connected to the second input port of the first optical coupler 3-1.

[0041] The fifth continuous wave laser 1-5 is connected to the input port of the third optical coupler 3-3, the first output port of the third optical coupler 3-3 is connected to the reflector, and is reflected back to the fifth continuous wave laser 1-5, generating a driving chaotic signal in an all-optical feedback manner and injecting it into the third optical coupler 3-3, the second output port of the third optical coupler 3-3 is connected to the input port of the fourth optical coupler 3-4, the first output port of the fourth optical coupler 3-4 is connected to the first input port of the wavelength division multiplexer, the second output port of the fourth optical coupler 3-4 is connected to the first port of the first circulator 9-1, the second port of the first circulator 9-1 is connected to the sixth continuous wave laser 1-6, the third port of the first circulator 9-1 is connected to the input port of the third photodetector 6-3, the output port of the third photodetector 6-3 is connected to the RF driving port of the first phase modulator 8-1, and the output port of the first phase modulator 8-1 is connected to the second input port of the wavelength division multiplexer.

[0042] In the public transmission channel, the output port of the wavelength division multiplexer is connected to the first port of the standard single-mode optical fiber 10, the second port of the standard single-mode optical fiber 10 is connected to the input port of the erbium-doped fiber amplifier 11, the output port of the erbium-doped fiber amplifier 11 is connected to the first port of the dispersion-compensating optical fiber 12, and the second port of the dispersion-compensating optical fiber 12 is connected to the input port of the wavelength division multiplexer.

[0043] At the receiving end, the first output port of the wavelength division multiplexer is connected to the first port of the second circulator 9-2, the second port of the second circulator 9-2 is connected to the seventh continuous wave laser 1-7, the third port of the second circulator 9-2 is connected to the input port of the fourth photodetector 6-4, and the output port of the fourth photodetector 6-4 is connected to the RF driving port of the second phase modulator 8-2; the second output port of the wavelength division multiplexer is connected to the input port of the second phase modulator 8-2, the output port of the second phase modulator 8-2 is connected to the input port of the second optical coupler 3-2, the first output port of the second optical coupler 3-2 is connected to the first port of the second delay line 4-2, the second port of the second delay line 4-2 is connected to the first port of the second variable photoelectric attenuator 5-2, and the second port of the second variable photoelectric attenuator 5-2 is connected to the second optical coupler 3-2. The input port of the electrical detector 6-2 is connected, the output port of the second photodetector 6-2 is connected to the input port of the second RF amplifier 7-2, the output port of the second RF amplifier 7-2 is connected to the RF driving port of the second Mach-Zehnder modulator 2-2, the second continuous wave laser 1-2 is connected to the input port of the second Mach-Zehnder modulator 2-2, the output port of the second Mach-Zehnder modulator 2-2 is connected to the second input port of the 90-degree optical mixer, the second output port of the second optical coupler 3-2 is connected to the first input port of the optical mixer, the third output port of the optical mixer is connected to the first input port of the coherent receiver, the fourth continuous wave laser 1-4 is connected to the second input port of the coherent receiver, the coherent receiver outputs a 16QAM electrical signal, and then the original binary plaintext information is restored through the 16QAM demapper.

[0044] In this embodiment, 16QAM optical modulation is used to modulate the binary plaintext information to be transmitted, and the plaintext information is made to participate in the generation of intensity chaos to achieve information hiding.

[0045] In this embodiment, the coupling coefficients of all couplers are 0.5.

[0046] In this embodiment, the parameters of the first continuous wave laser and the second continuous wave laser are the same; the parameters of the third continuous wave laser and the fourth continuous wave laser are the same; and the parameters of the sixth continuous wave laser and the seventh continuous wave laser are the same. The parameters of the first Mach-Zehnder modulator and the second Mach-Zehnder modulator are the same. The parameters of the first delay line and the second delay line are the same; and the parameters of the first variable optical attenuator and the second variable optical attenuator are the same. The parameters of the first photodetector and the second photodetector are the same; the parameters of the third photodetector and the fourth photodetector are the same; and the parameters of the first radio frequency amplifier and the second radio frequency amplifier are the same. The parameters of the first phase modulator and the second phase modulator are the same.

[0047] In this embodiment, the signal transmission rate is 40 Gb / s.

[0048] In the optical communication system based on amplitude-phase dual-dimensional chaotic encryption disclosed in this embodiment, the signal encryption and decryption principles are as follows:

[0049] At the transmitter, the optical signal emitted by the third continuous-wave laser undergoes in-phase and quadrature modulation to generate the plaintext signal used for optical chaotic encryption. This signal then participates in the generation of the intensity chaotic signal after passing through the third variable optical attenuator and the first optical coupler. The optical signal emitted by the first continuous-wave laser undergoes electro-optical delay feedback to generate an intensity chaotic signal, thereby achieving intensity encryption of the plaintext signal. The optical signal emitted by the fifth continuous-wave laser undergoes all-optical feedback to generate a driving chaotic signal, which is injected into the sixth continuous-wave laser to generate a phase chaotic signal. The intensity-encrypted signal is then subjected to phase encryption again using the first phase modulator, achieving encryption of the plaintext signal in both intensity and phase dimensions. During this process, the plaintext information participates in the generation of the optical intensity chaos, increasing the complexity of the chaotic signal. The open-loop structure of the electro-optical delay feedback loop provides strong robustness to the system. The device parameters in each module further expand the key space, enhancing the security of the chaotic communication system.

[0050] At the receiving end, a structure symmetrical to that of the transmitting end is used to implement chaotic decryption. A phase chaotic signal synchronized with the transmitting end is first generated, and a second phase modulator is used to perform phase decryption. A second optical coupler then splits the signal into two beams: one for intensity decryption and the other to induce intensity chaos. A 90-degree optical mixer then performs a phase subtraction operation to achieve intensity decryption. Signal demodulation then proceeds by coherently detecting the intensity decrypted signal with the optical signal generated by a fourth continuous-wave laser, which has the same parameters as the third continuous-wave laser at the transmitting end. Finally, 16QAM inverse mapping is used to recover the original binary plaintext signal.

[0051] The process of implementing communication in the optical communication system based on amplitude-phase dual-dimensional chaotic encryption in this embodiment is briefly described as follows:

[0052] 1. Set parameters to generate intensity chaotic signals by coupling optical information through electro-optical time delay feedback, and generate phase chaotic signals through all-optical feedback combined with optical injection, further enhancing the complexity of the chaotic signals.

[0053] 2. The light signal participates in the generation process of the intensity chaotic signal to achieve intensity encryption. The phase chaotic signal is converted into an electrical signal through a photodetector, and the phase modulator is used to achieve phase encryption of the intensity encrypted signal.

[0054] 3. The receiving end adopts a symmetrical structure with the transmitting end. It first performs phase decryption on the encrypted signal carrying the plaintext information through a synchronized phase chaotic signal. Then, it performs intensity chaotic decryption on the phase decrypted signal and the synchronized intensity chaotic signal through an optical mixer. Finally, the transmitted binary plaintext information is obtained through a coherent receiver and 16QAM inverse mapping.

[0055] The above embodiment demonstrates chaotic encryption of binary plaintext information after optical 16QAM signal modulation. However, the present invention is not limited to this single signal format and can also effectively protect other signals with amplitude and phase information, such as quadrature phase shift keying (QPSK) signals.

[0056] The above is a preferred embodiment of the present invention and does not limit the scope of protection of the present invention. For ordinary technicians in this field, based on the research ideas provided by the present invention, there will be improvements in the specific design scheme, and these changes should also be regarded as the scope of protection of the present invention.

Claims

1. An optical communication system based on amplitude-phase dual-dimensional chaotic encryption, including a transmitter and a receiver, is characterized by: At the transmitting end, the binary plaintext signal is converted into an electrical signal by a mapper and injected into an in-phase quadrature modulator; a third optical signal emitted by a third continuous wave laser (1-3) enters the in-phase quadrature modulator, and the in-phase quadrature modulator modulates the electrical signal into an optical signal to obtain a plaintext signal for optical chaos encryption. The optical signal passes through a third variable optical attenuator (5-3) and then enters the first optical attenuator (3-1); A first optical signal emitted by a first continuous wave laser (1-1) passes through a first Mach-Zehnder modulator (2-1) and enters a first optical coupler (3-1) to be divided into two optical signals, namely, a first optical signal and a second optical signal. The first optical signal is coupled with a plaintext signal and then enters a first phase modulator (8-1). The second optical signal is coupled with the plaintext signal and then passes through a first delay line (4-1), a first variable optical attenuator (5-1), a first photodetector (6-1), and a first radio frequency amplifier (7-1) in sequence before entering the first Mach-Zehnder modulator (2-1). The fifth continuous wave laser (1-5) is split into two beams after passing through the third optical coupler (3-3), one beam is projected onto a reflector, and the other beam is split into two optical signals after passing through the fourth optical coupler (3-4), wherein the first beam enters the first input port of the wavelength division multiplexer, the second beam passes through the first circulator (9-1) and enters the sixth continuous wave laser (1-6), then returns to the first circulator (9-1), and then enters the first phase modulator (8-1) through the third photodetector (6-3), the output port of the first phase modulator (8-1) is connected to the second input port of the wavelength division multiplexer, and the output port of the wavelength division multiplexer is connected to the receiving end through an optical fiber; At the receiving end, the signal transmitted through the optical fiber link is divided into two beams by the wavelength division multiplexer. One beam passes through the second circulator (9-2) and enters the seventh continuous wave laser (1-7), then returns to the second circulator (9-2), and then passes through the fourth photodetector (6-4) and enters the second phase modulator (8-2). The other beam enters the second phase modulator (8-2). The optical signal after phase decryption by the second phase modulator (8-2) is divided into two beams after passing through the second optical coupler (3-2). One beam of light enters the first input port of the 90-degree optical mixer, and the other beam passes through the second delay line (4-2), the second variable photoelectric attenuator (5-2), the second photodetector (6-2), and the second radio frequency amplifier (7-2) in sequence before entering the second Mach-Zehnder modulator (2-2). The optical signal emitted by the second continuous wave laser (1-2) passes through the second Mach-Zehnder modulator (2-2) and enters the second input port of the 90-degree optical mixer. Intensity decryption is achieved by subtracting a 90-degree optical mixer. The 90-degree optical mixer is connected to a first input port of a coherent receiver. A fourth continuous wave laser (1-4) is connected to a second input port of the coherent receiver. An electrical signal is obtained through the coherent receiver, and then the original binary plaintext information is restored through an inverse mapper.

2. The optical communication system based on amplitude-phase dual-dimensional chaotic encryption according to claim 1, characterized in that: The parameters of the first continuous wave laser and the second continuous wave laser are the same; the parameters of the third continuous wave laser and the fourth continuous wave laser are the same; and the parameters of the sixth continuous wave laser and the seventh continuous wave laser are the same.

3. The optical communication system based on amplitude-phase dual-dimensional chaotic encryption according to claim 1, characterized in that: The first Mach-Zehnder modulator and the second Mach-Zehnder modulator have the same parameters.

4. The optical communication system based on amplitude-phase dual-dimensional chaotic encryption according to claim 1, characterized in that: The coupling coefficients of the first optical coupler, the second optical coupler, the third optical coupler, and the fourth optical coupler are all 0.

5.

5. The optical communication system based on amplitude-phase dual-dimensional chaotic encryption according to claim 1, characterized in that: The output port of the wavelength division multiplexer is connected to the receiving end through a standard single-mode optical fiber (10), an erbium-doped optical fiber amplifier (11) and a dispersion compensation optical fiber (12) in sequence.

6. The optical communication system based on amplitude-phase dual-dimensional chaotic encryption according to claim 1, characterized in that: The parameters of the first delay line and the second delay line are the same; and the parameters of the first variable optical attenuator and the second variable optical attenuator are the same.

7. The optical communication system based on amplitude-phase dual-dimensional chaotic encryption according to claim 1, characterized in that: The first photodetector and the second photodetector have the same parameters; the third photodetector and the fourth photodetector have the same parameters; and the first radio frequency amplifier and the second radio frequency amplifier have the same parameters.

8. The optical communication system based on amplitude-phase dual-dimensional chaotic encryption according to any one of claims 1 to 7, characterized in that: The first phase modulator and the second phase modulator have the same parameters.

9. An optical communication method based on amplitude-phase dual-dimensional chaotic encryption, based on the system according to any one of claims 1 to 8, characterized in that: The specific steps of the method are as follows: At the transmitting end, the binary plaintext signal is converted into an electrical signal through a mapper and injected into an in-phase quadrature modulator; the optical signal emitted by the third continuous wave laser (1-3) is subjected to in-phase quadrature modulation to obtain a plaintext signal for optical chaos encryption, and the signal enters the first optical coupler (3-1) through the third variable optical attenuator (5-3) to participate in the generation of an intensity chaotic signal; the optical signal emitted by the first continuous wave laser (1-1) is fed back through electro-optical time delay to generate an intensity chaotic signal, thereby achieving intensity encryption of the plaintext signal; The optical signal emitted by the fifth continuous wave laser (1-5) generates a driving chaotic signal through all-optical feedback, and the driving chaotic signal is injected into the sixth continuous wave laser (1-6) to generate a phase chaotic signal. The intensity-encrypted signal is then phase-encrypted again using the first phase modulator (8-1), thereby achieving encryption of the plaintext signal in both intensity and phase dimensions. At the receiving end, a phase chaos signal synchronized with the transmitting end is generated, and phase decryption is completed using a second phase modulator (8-2); then, the signal is divided into two beams through a second optical coupler (3-2), one beam for intensity decryption and the other beam for inducing the generation of intensity chaos; then, a phase subtraction operation is performed through a 90-degree optical mixer to achieve intensity decryption; then, signal demodulation is performed, and the intensity-decrypted signal and the optical signal generated by the fourth continuous-wave laser (1-4) are first coherently detected, and finally, the original binary plaintext signal is restored through inverse mapping.

10. The optical communication method based on amplitude-phase dual-dimensional chaotic encryption according to claim 9, characterized in that: The signal transmission rate is 40Gb / s.

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