Variable-parameter electro-optical delay optical communication system and method based on double-feedback chaotic input

Abstract

The invention discloses a variable-parameter electro-optical time delay optical communication system and method based on double-feedback chaotic input, in the system, light of a first laser is divided into two beams after passing through a circulator and the like, and one beam enters a phase modulator through an adjustable delay line and the like; the other beam is divided into two beams by an optical coupler, and the first beam is injected into a circulator through a variable optical attenuator and the like; the second beam is coupled with a light text signal through a variable optical attenuator and the like and then is divided into two beams, and one beam enters a Mach-Zehnder modulator through an adjustable delay line and the like; and the other beam is used for channel transmission. Light of the third laser is divided into two beams after passing through a circulator and the like, and one beam enters a phase modulator through an adjustable delay line and the like; the other beam is divided into two beams through an optical coupler, and the first beam passes through a variable optical attenuator and the like and then is injected into a circulator; the second beam is injected into a subtracter through a variable optical attenuator and the like; light transmitted by a channel is divided into two beams by an optical coupler, and one beam passes through an adjustable delay line and the like and then enters a Mach-Zehnder modulator; and the other beam enters a subtracter through a photoelectric detector.

Description

Technical Field

[0001] The present invention belongs to the field of optical information technology, and in particular relates to a variable-parameter electro-optical delay optical communication system and method based on double-feedback chaotic input. Background Art

[0002] Chaotic signals have shown significant advantages in high-speed, long-distance secure communication applications due to their unique characteristics of seemingly random, wide bandwidth, noise-like and extremely sensitive to initial values. Compared with traditional secure communication systems based on application-layer digital encryption technology, chaotic signals have more outstanding security by performing chaotic encryption on plaintext signals at the physical layer.

[0003] At present, although optical chaotic secure communication systems have been developed, they still face problems such as insufficient confidentiality and low information transmission efficiency. To meet these challenges, the present invention innovatively proposes a variable-parameter electro-optical delay optical communication technology based on double feedback chaotic input. By introducing a double feedback chaotic input mechanism, it has achieved remarkable results in expanding the key space, and enables plaintext information to directly participate in the generation of chaotic signals, effectively improving the transmission efficiency and security of the communication system. Summary of the invention

[0004] In view of the above-mentioned status quo of the prior art, the present invention improves the complexity and transmission rate of chaotic signals, involves plaintext signals in the generation process of chaotic signals, effectively improves the security and reliability of optical chaotic communication, and adopts double feedback chaos as input to generate encrypted chaotic signals. A variable-parameter electro-optical delay optical communication system and method based on double feedback chaotic input is designed.

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

[0006] The variable parameter electro-optical time-delay optical communication system based on double feedback chaotic input includes a transmitting end and a receiving end, and the transmitting end and the receiving end are connected through an optical fiber link, as follows:

[0007] At the transmitting end, the second optical signal emitted by the second continuous wave laser enters the second Mach-Zehnder modulator, and the four-level pulse amplitude modulation (PAM4) signal m(t) is modulated into an optical signal by the second Mach-Zehnder modulator to obtain a plaintext signal for optical chaos encryption, and the plaintext signal enters the third optical coupler;

[0008] The first optical signal emitted by the first continuous wave laser passes through the first circulator and the first phase modulator in sequence, and then enters the first optical coupler to be divided into two optical signals, namely, the first optical signal and the second optical signal. The first optical signal passes through the second adjustable delay line, the second variable optical attenuator, the first photodetector, and the first radio frequency amplifier in sequence, and then enters the first phase modulator; the second optical signal is divided into two beams, namely, the 2-1 beam and the 2-2 beam, by the second optical coupler. The 2-1 beam passes through the first optical variable attenuator, the first adjustable delay line, the first polarization controller, and the first circulator in sequence, and then enters the first continuous wave laser; the 2-2 beam passes through the third variable optical attenuator and the first Mach-Zehnder modulator in sequence, enters the third optical coupler, and is coupled with the optical signal to be divided into two beams, namely, the 2-2-1 beam and the 2-2-2 beam. The 2-2-1 beam passes through the third adjustable delay line, the fourth variable optical attenuator, the second photodetector, and the second radio frequency driver in sequence, and then enters the first Mach-Zehnder modulator; the 2-2-2 beam enters the receiving end through optical fiber transmission;

[0009] At the receiving end, the signal transmitted through the optical fiber link is divided into two beams, namely, the 2-2-2-1 beam and the 2-2-2-2 beam, through the sixth optical coupler. The 2-2-2-1 beam passes through the sixth photodetector and then enters the subtractor. The 2-2-2-2 beam passes through the sixth adjustable delay line, the eighth variable optical attenuator, the fourth photodetector, and the fourth radio frequency driver in sequence and then enters the third Mach-Zehnder modulator.

[0010] At the receiving end, the third optical signal emitted by the third continuous wave laser passes through the second circulator and the second phase modulator in sequence, then enters the fourth optical coupler and is divided into two optical signals, namely the third optical signal and the fourth optical signal. The third optical signal passes through the fifth adjustable delay line, the sixth variable optical attenuator, the third photodetector, and the third radio frequency amplifier in sequence, then enters the second phase modulator; the fourth optical signal is divided into two beams, namely the 4-1 beam and the 4-2 beam, by the fifth optical coupler. The 4-1 beam passes through the fifth optical variable attenuator, the fourth adjustable delay line, the second polarization controller, and the second circulator in sequence, then enters the third continuous wave laser; the 4-2 beam passes through the seventh variable optical attenuator and then enters the third Mach-Zehnder modulator, and is modulated by the received signal after channel transmission, namely the 2-2-2-2 beam signal, to generate a synchronized chaotic signal, which passes through the fifth photodetector and then enters the subtractor, and finally is decrypted by performing a subtraction operation through the subtractor.

[0011] In the present invention, the transmitting end includes three major parts: signal modulation, double feedback chaos generation and chaos encryption. In the signal modulation process, the second optical signal emitted by the second continuous wave laser enters the second Mach-Zehnder modulator, and the four-level pulse amplitude modulation (PAM4) signal is modulated into an optical signal through light intensity modulation, thereby obtaining a plaintext signal for optical chaos encryption. After the plaintext signal enters the third optical coupler, it is divided into two beams, one of which participates in the generation process of encrypted chaos; the other enters the channel for transmission. In the double feedback chaos generation process, the first optical signal emitted by the first continuous wave laser passes through the first circulator and the first phase modulator in sequence and enters the first optical coupler, and is divided into two beams, one of which passes through the second adjustable delay line, the second variable optical attenuator, the first photodetector, and the first radio frequency amplifier in sequence and enters the first phase modulator; the other beam is divided into two beams by the second optical coupler, the first beam passes through the first optical variable attenuator, the first adjustable delay line, the first polarization controller, and the first circulator in sequence and enters the first continuous wave laser; the second beam passes through the third variable optical attenuator and is injected into the first Mach-Zehnder modulator. During the chaotic encryption process, the output signal of the first Mach-Zehnder modulator is coupled with the optical signal through the third optical coupler and then divided into two beams. One beam passes through the third adjustable delay line, the fourth variable optical attenuator, the second photodetector, and the second RF driver in sequence and then enters the first Mach-Zehnder modulator; the other beam is connected to the receiving end through optical fiber.

[0012] The receiving end adopts an open-loop symmetrical structure with the transmitting end, which mainly includes three parts: synchronous chaos generation, dual-feedback chaos generation and chaos decryption. In the synchronous chaos generation process, the signal transmitted through the optical fiber link is divided into two beams through the sixth optical coupler, one beam passes through the sixth photodetector and enters the subtractor, and the other beam passes through the sixth adjustable delay line, the eighth variable optical attenuator, the fourth photodetector, and the fourth radio frequency driver in turn and enters the radio frequency drive port of the third Mach-Zehnder modulator. In the dual-feedback chaos generation process, the third optical signal emitted by the third continuous wave laser passes through the second circulator and the second phase modulator in turn and enters the fourth optical coupler and is divided into two optical signals. The first optical signal passes through the fifth adjustable delay line, the sixth variable optical attenuator, the third photodetector, and the third radio frequency amplifier in turn and enters the second phase modulator; the second optical signal is divided into two beams by the fifth optical coupler, and one beam passes through the fifth optical variable attenuator, the fourth adjustable delay line, the second polarization controller, and the second circulator in turn and enters the third continuous wave laser. During the chaotic decryption process, another beam of generated synchronous chaotic optical signal passes through the seventh variable optical attenuator, the third Mach-Zehnder modulator, and the fifth photodetector and then enters the subtractor. Finally, the output signal and the encrypted signal transmitted to the sixth photodetector via the optical fiber link are subtracted through the subtractor to realize the decryption operation.

[0013] As a preferred solution, according to the PAM4 plaintext information to be transmitted, the light intensity is modulated into a light text signal to perform optical chaotic encryption and transmission; and the light text signal is involved in the generation process of the encrypted chaotic carrier, which also means that the plaintext information is hidden.

[0014] As a preferred solution, the parameters of the corresponding devices between the transmitting end and the receiving end are the same, such as: the parameters of the first laser and the third laser are the same; the parameters of the first phase modulator and the second phase modulator are the same; the parameters of the first optical coupler, the second optical coupler, the third optical coupler, the fourth optical coupler, the fifth optical coupler and the sixth optical coupler are the same, such as the coupling coefficients are all 0.5; the parameters of the first adjustable delay line and the fourth adjustable delay line are the same; the parameters of the second adjustable delay line and the fifth adjustable delay line are the same; the parameters of the third adjustable delay line and the sixth adjustable delay line are the same; the parameters of the first variable optical attenuator and the fifth variable optical attenuator are the same. The parameters of the first photodetector and the third photodetector are the same; the parameters of the second photodetector and the fourth photodetector are the same; the parameters of the fifth photodetector and the sixth photodetector are the same; the parameters of the first radio frequency amplifier and the third radio frequency amplifier are the same; the parameters of the second radio frequency amplifier and the fourth radio frequency amplifier are the same; the parameters of the first Mach-Zehnder modulator and the third Mach-Zehnder modulator are the same.

[0015] In the present invention, the double feedback chaos generation process at the transmitting end generates a first optical chaotic signal through double feedback as the input of the chaotic encryption process, and the chaotic encryption process generates a second optical chaotic signal through electro-optical delay feedback, and the light text signal is coupled into the electro-optical delay feedback loop to participate in the generation of the second optical chaotic signal, thereby realizing the hiding of the light text signal, and the encrypted signal enters the optical fiber transmission link. At the receiving end, a symmetrical structure is used with the transmitting end to generate the same double feedback chaotic input signal; and the received encrypted signal is used to induce the generation of a synchronous chaotic signal, and finally a subtractor is used to perform a subtraction operation to restore the plaintext information.

[0016] As a preferred solution, the coupling coefficients of all couplers are 0.5.

[0017] As a preferred solution, the communication system signal transmission rate is 20 Gb / s.

[0018] As a preferred solution, the receiving end recovers the plaintext information through a subtractor.

[0019] The present invention also discloses a variable parameter electro-optical delay optical communication method based on double feedback chaotic input. Based on the above system, the method has the following specific steps:

[0020] At the transmitting end, the optical signal emitted by the first continuous wave laser is fed back to the first continuous wave laser after self-phase modulation to generate a double feedback chaotic signal. The signal passes through the third variable optical attenuator as the input of the first Mach-Zehnder modulator, and generates a new chaotic signal through electro-optical delay feedback; the PAM4 plaintext signal is injected into the RF drive port of the second Mach-Zehnder modulator, and the optical signal emitted by the second continuous wave laser is modulated by the second Mach-Zehnder modulator to obtain a light text signal. The signal participates in the electro-optical delay feedback through the third optical coupler to achieve signal encryption. In this process, the plaintext information participates in the generation process of encrypted chaos, which enhances the complexity of the chaotic signal. And because of the open-loop structure, the system has strong robustness, and the device parameters in each module further expand the key space, which improves the security of the chaotic communication system.

[0021] At the receiving end, a double-feedback chaotic signal is generated by adopting a structure that is symmetrical with the open loop at the transmitting end. The signal passes through the seventh variable optical attenuator and serves as the input of the third Mach-Zehnder modulator. The signal is modulated by the received signal after channel transmission to generate a synchronized chaotic signal. Finally, a subtractor is used to subtract the synchronized chaotic signal and the received signal that pass through the fifth photodetector and the sixth photodetector respectively to achieve decryption.

[0022] At the transmitting end of the present invention, the optical signal emitted by the first continuous wave laser generates a first chaotic signal through double feedback, and the chaotic signal is used as input to generate a second chaotic signal for encryption through electro-optical delay feedback. The optical signal emitted by the second continuous wave laser is passed through the second Mach-Zehnder modulator to obtain a light signal for optical chaos encryption, which participates in the generation process of encrypted chaos through the third optical coupler and realizes the chaotic encryption operation.

[0023] At the receiving end of the present invention, a structure symmetrical to that of the transmitting end is used to realize chaotic decryption. The same double-feedback chaotic signal as that of the transmitting end is generated by a third continuous wave laser and injected into the third Mach-Zehnder modulator. The encrypted signal transmitted through the optical fiber link is divided into two beams by a sixth optical coupler, one beam is used for chaotic decryption, and the other beam is used to induce an encrypted chaotic signal synchronized with the transmitting end. Finally, a subtractor is used to subtract the encrypted signal from the output of the third Mach-Zehnder modulator for decryption.

[0024] Preferably, the transmission rate of the signal is set to 20 Gb / s.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention is based on a variable parameter electro-optical delay optical communication system and method with double feedback chaotic input. At the transmitting end, the PAM4 plaintext information is first modulated for optical intensity to obtain a light text signal; a first chaotic signal is generated through a double feedback mechanism, and an encrypted chaotic signal is generated as an input through electro-optical delay feedback, which further expands the key space, effectively reduces the violent attack of illegal eavesdroppers, and further improves the security and reliability of communication. In the electro-optical delay feedback process, the light text signal is involved in the generation process of the encrypted chaotic signal through a coupler to complete chaotic encryption. By allowing the plaintext information to participate in the generation of chaos, not only the complexity of the chaotic signal is increased, but also the plaintext information is effectively hidden, further improving the security of information transmission and effectively preventing the signal from being intercepted. In addition, the present invention adopts an open-loop symmetrical structure to achieve chaotic synchronization, which makes the communication system more robust. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] Figure 1 It is a schematic diagram of the architecture of a variable-parameter electro-optical delay optical communication system based on double-feedback chaotic input according to a preferred embodiment of the present invention.

[0029] Figure 2 This is a time domain waveform diagram of a PAM4 signal input at the transmitting end in a variable-parameter electro-optical delay optical communication system based on double feedback chaotic input in a preferred embodiment of the present invention.

[0030] Figure 3 This is a time domain waveform diagram of a decrypted PAM4 signal in a variable-parameter electro-optical delay optical communication system based on double-feedback chaotic input in a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0031] In order to more clearly illustrate the embodiments of the present invention, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other accompanying drawings and other implementation methods can be obtained based on these accompanying drawings without creative work.

[0032] like Figure 1 As shown, this embodiment is a variable parameter electro-optical delay optical communication system based on double feedback chaotic input, including a transmitting end and a receiving end, wherein:

[0033] The transmitting end components include a first continuous wave laser 1-1, a second continuous wave laser 1-2, a first circulator 2-1, a first phase modulator 3-1, a first optical coupler 4-1, a second optical coupler 4-2, a third optical coupler 4-3, a first variable optical attenuator 5-1, a second variable optical attenuator 5-2, a third variable optical attenuator 5-3, a fourth variable optical attenuator 5-4, a first adjustable delay line 6-1, a second adjustable delay line 6-2, a third adjustable delay line 6-3, a first polarization controller 7-1, a first photodetector 8-1, a second photodetector 8-2, a first radio frequency amplifier 9-1, a second radio frequency amplifier 9-2, a first Mach-Zehnder modulator 10-1, and a second Mach-Zehnder modulator 10-2;

[0034] The receiving end components include a third continuous wave laser 1-3, a second circulator 2-2, a second phase modulator 3-2, a fourth optical coupler 4-4, a fifth optical coupler 4-5, a sixth optical coupler 4-6, a fifth variable optical attenuator 5-5, a sixth variable optical attenuator 5-6, a seventh variable optical attenuator 5-7, an eighth variable optical attenuator 5-8, a fourth adjustable delay line 6-4, a fifth adjustable delay line 6-5, a sixth adjustable delay line 6-6, a second polarization controller 7-2, a third photodetector 8-3, a fourth photodetector 8-4, a fifth photodetector 8-5, a sixth photodetector 8-6, a third radio frequency amplifier 9-3, a fourth radio frequency amplifier 9-4, a third Mach-Zehnder modulator 10-3, and a subtractor 14;

[0035] The transmitting end and the receiving end are connected through a standard single-mode optical fiber 11 , an erbium-doped optical fiber amplifier 12 and a dispersion compensation optical fiber 13 .

[0036] The specific connection methods of the above components are as follows:

[0037] In the transmitting end, the first continuous wave laser 1-1 is connected to the first port of the first circulator 2-1, the second port of the first circulator 2-1 is connected to the input port of the first phase modulator 3-1, the output port of the first phase modulator 3-1 is connected to the input port of the first optical coupler 4-1, the first output port of the first optical coupler 4-1 is connected to the first port of the second adjustable delay line 6-2, the second port of the second adjustable delay line 6-2 is connected to the first port of the second variable optical attenuator 5-2, the second port of the second variable optical attenuator 5-2 is connected to the input port of the first photodetector 8-1, and the output port of the first photodetector 8-1 is connected to the first transmitting end. The first RF amplifier 9-1 is connected to the input port of the first frequency amplifier 9-1, and the output port of the first RF amplifier 9-1 is connected to the RF driving port of the first phase modulator 3-1; the second output port of the first optical coupler 4-1 is connected to the input port of the second optical coupler 4-2, the first output port of the second optical coupler 4-2 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 first port of the first adjustable delay line 6-1, the second port of the first adjustable delay line 6-1 is connected to the first port of the first polarization controller 7-1, and the second port of the first polarization controller 7-1 is connected to the third port of the first circulator 2-1.

[0038] The second output port of the second optical coupler 4-2 is connected to the first port of the third variable optical attenuator 5-3, the second port of the third variable optical attenuator 5-3 is connected to the input port of the first Mach-Zehnder modulator 10-1, the output port of the first Mach-Zehnder modulator 10-1 is connected to the first input port of the third optical coupler 4-3, the first output port of the third optical coupler 4-3 is connected to the first port of the third adjustable delay line 6-3, the second port of the third adjustable delay line 6-3 is connected to the first port of the fourth variable optical attenuator 5-4, the second port of the fourth variable optical attenuator 5-4 is connected to the input port of the second photodetector 8-2, the output port of the second photodetector 8-2 is connected to the input port of the second radio frequency amplifier 9-2, and the output port of the second radio frequency amplifier 9-2 is connected to the radio frequency driving port of the first Mach-Zehnder modulator 10-1.

[0039] The second continuous wave laser 1-2 is connected to the input port of the second Mach-Zehnder modulator 10-2, the output port of the second Mach-Zehnder modulator 10-2 is connected to the second input port of the third optical coupler 4-3, and the PAM4 plaintext signal m(t) is input to the RF driving port of the second Mach-Zehnder modulator 10-2.

[0040] In the common transmission channel, the second output port of the third optical coupler 4-3 is connected to the first port of the standard single-mode optical fiber 11, the second port of the standard single-mode optical fiber 11 is connected to the input port of the erbium-doped fiber amplifier 12, the output port of the erbium-doped fiber amplifier 12 is connected to the first port of the dispersion-compensating optical fiber 13, and the second port of the dispersion-compensating optical fiber 13 is connected to the input port of the sixth optical coupler 4-6.

[0041] In the receiving end, the third continuous wave laser 1-3 is connected to the first port of the second circulator 2-2, the second port of the second circulator 2-2 is connected to the input port of the second phase modulator 3-2, the output port of the second phase modulator 3-2 is connected to the input port of the fourth optical coupler 4-4, the first output port of the fourth optical coupler 4-4 is connected to the first port of the fifth adjustable delay line 6-5, the second port of the fifth adjustable delay line 6-5 is connected to the first port of the sixth variable optical attenuator 5-6, the second port of the sixth variable optical attenuator 5-6 is connected to the input port of the third photodetector 8-3, and the output port of the third photodetector 8-3 is connected to the third emitter. The input port of the third RF amplifier 9-3 is connected, and the output port of the third RF amplifier 9-3 is connected to the RF driving port of the second phase modulator 3-2; the second output port of the fourth optical coupler 4-4 is connected to the input port of the fifth optical coupler 4-5, the first output port of the fifth optical coupler 4-5 is connected to the first port of the fifth variable optical attenuator 5-5, the second port of the fifth variable optical attenuator 5-5 is connected to the first port of the fourth adjustable delay line 6-4, the second port of the fourth adjustable delay line 6-4 is connected to the first port of the second polarization controller 7-2, and the second port of the second polarization controller 7-2 is connected to the third port of the second circulator 2-2.

[0042] The first output port of the sixth optical coupler 4-6 is connected to the input port of the sixth photodetector 8-6, and the output port of the sixth photodetector 8-6 is connected to the subtractor 14; the second output port of the sixth optical coupler 4-6 is connected to the first port of the sixth adjustable delay line 6-6, the second port of the sixth adjustable delay line 6-6 is connected to the first port of the eighth variable optical attenuator 5-8, the second port of the eighth variable optical attenuator 5-8 is connected to the input port of the fourth phase modulator 8-4, the output port of the fourth phase modulator 8-4 is connected to the input port of the fourth radio frequency amplifier 9-4, and the output port of the fourth radio frequency amplifier 9-4 is connected to the radio frequency drive port of the third Mach-Zehnder modulator 10-3.

[0043] The second output port of the fifth optical coupler 4-5 is connected to the first port of the seventh variable optical attenuator 5-7, the second port of the seventh variable optical attenuator 5-7 is connected to the input port of the third Mach-Zehnder modulator 10-3, the output port of the third Mach-Zehnder modulator 10-3 is connected to the input port of the fifth photodetector 8-5, the output port of the fifth photodetector 8-5 is connected to the subtractor 14, and finally the decrypted signal m'(t) is obtained through the subtractor 14.

[0044] In this embodiment, light intensity modulation is used to modulate the PAM4 plaintext information to be transmitted, and the plaintext information is made to participate in the generation of encrypted chaos to achieve information hiding.

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

[0046] This embodiment is a variable parameter electro-optical delay optical communication system based on double feedback chaotic input, and the principle of signal encryption and decryption is briefly described as follows:

[0047] At the transmitting end, the light signal emitted by the second continuous wave laser is modulated by light intensity to obtain the plaintext signal used for optical chaos encryption. After passing through the third optical coupler, the signal participates in the generation process of the encrypted chaotic signal and realizes the intensity encryption of the light text signal. The light signal emitted by the first continuous wave laser generates the first chaotic signal through double feedback, and this signal is injected into the first Mach-Zehnder modulator to generate an encrypted chaotic signal. In this process, the plaintext information participates in the generation process of light intensity chaos, which enhances the complexity of the chaotic signal. Moreover, due to the adoption of an open-loop structure, the system has strong robustness, and the parameters of each device further expand the key space, thereby improving the security of the chaotic communication system.

[0048] At the receiving end, a symmetrical structure with the transmitting end is used to realize chaotic decryption. First, the same chaos as the first chaotic signal is generated and injected into the third Mach-Zehnder modulator; then the received signal from the channel is divided into two beams through the sixth optical coupler, one beam is used for chaotic decryption, and the other beam is used to induce the generation of synchronous chaos; finally, the encrypted signal and the synchronous chaotic signal are subtracted through the subtractor to realize chaotic decryption and restore the plaintext signal.

[0049] The process of realizing communication by the variable-parameter electro-optical delay optical communication system based on double-feedback chaotic input in this embodiment is briefly described as follows:

[0050] 1. Set parameters, use double feedback chaos as the input of encrypted chaotic signal, and generate encrypted chaotic signal by coupling light text information through electro-optical time delay feedback, so as to further enhance the complexity of chaotic signal.

[0051] 2. The bright text signal participates in the generation process of the encrypted chaotic signal to realize chaotic encryption.

[0052] 3. The receiving end adopts a symmetrical structure with the transmitting end. It first generates the same double-feedback chaotic input signal, then uses the received encrypted signal to induce the generation of a synchronous chaotic signal, and finally recovers the plaintext information by performing a subtraction operation through a subtractor.

[0053] The above are preferred implementations of the present invention and do not limit the protection scope of the present invention. For ordinary technicians in this field, according to 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 protection scope of the present invention.

Claims

1. A variable-parameter electro-optical delay optical communication system based on double-feedback chaotic input, comprising a transmitting end and a receiving end, characterized in that: At the transmitting end, the second optical signal emitted by the second continuous wave laser (1-2) enters the second Mach-Zehnder modulator (10-2), and the four-level pulse amplitude modulation signal is modulated into an optical signal by the second Mach-Zehnder modulator (10-2), thereby obtaining a plaintext signal for optical chaos encryption, and the plaintext signal enters the third optical coupler (4-3); A first optical signal emitted by a first continuous wave laser (1-1) passes through a first circulator (2-1) and a first phase modulator (3-1) in sequence, and then enters a first optical coupler (4-1) to be divided into two optical signals, namely, a first optical signal and a second optical signal. The first optical signal passes through a second adjustable delay line (6-2), a second variable optical attenuator (5-2), a first photodetector (8-1), and a first radio frequency amplifier (9-1) in sequence, and then enters the first phase modulator (3-1). The second optical signal is divided into two optical signals, namely, a 2-1 beam and a 2-2 beam, by the second optical coupler (4-2). The 2-1 beam passes through the first optical variable attenuator (5-1), the first adjustable delay line (6-2), the first photodetector (8-1), and the first radio frequency amplifier (9-1) in sequence. -1), a first polarization controller (7-1), and a first circulator (2-1), and then enter the first continuous wave laser (1-1); the 2-2 beam passes through the third variable optical attenuator (5-3) and the first Mach-Zehnder modulator (10-1) in sequence, and enters the third optical coupler (4-3) and is coupled with the optical signal to be divided into two beams, namely the 2-2-1 beam and the 2-2-2 beam; the 2-2-1 beam passes through the third adjustable delay line (6-3), the fourth variable optical attenuator (5-4), the second photodetector (8-2), and the second radio frequency driver (9-2) in sequence, and then enters the first Mach-Zehnder modulator (10-1); the 2-2-2 beam is transmitted to the receiving end; The signal received by the receiving end is divided into two beams, namely the 2-2-2-1 beam and the 2-2-2-2 beam, by the sixth optical coupler (4-6); the 2-2-2-1 beam passes through the sixth photodetector (8-6) and then enters the subtractor (14); the 2-2-2-2 beam passes through the sixth adjustable delay line (6-6), the eighth variable optical attenuator (5-8), the fourth photodetector (8-4), and the fourth radio frequency driver (9-4) in sequence and then enters the third Mach-Zehnder modulator (10-3); At the receiving end, the third optical signal emitted by the third continuous wave laser (1-3) passes through the second circulator (2-2) and the second phase modulator (3-2) in sequence, and then enters the fourth optical coupler (4-4) and is divided into two optical signals, namely, the third optical signal and the fourth optical signal. The third optical signal passes through the fifth adjustable delay line (6-5), the sixth variable optical attenuator (5-6), the third photodetector (8-3), and the third radio frequency amplifier (9-3) in sequence, and then enters the second phase modulator (3-2). The fourth optical signal is divided into two beams, namely, the 4-1 beam and the 4-2 beam, by the fifth optical coupler (4-5). The 4-1 beam passes through the fifth optical variable attenuator (5-5), the fourth adjustable delay line (6-4), the second polarization controller (7-2), and the second circulator (2-2) in sequence, and then enters the third continuous wave laser (1-3); the 4-2 beam passes through the seventh variable optical attenuator (5-7) and then enters the third Mach-Zehnder modulator (10-3), and is modulated by using the received signal after channel transmission, i.e., the 2-2-2-2 beam signal, to generate a synchronized chaotic signal, and the chaotic signal passes through the fifth photodetector (8-5) and then enters the subtractor (14), and finally is decrypted by subtraction through the subtractor (14).

2. According to claim 1, the variable parameter electro-optical delay optical communication system based on double feedback chaotic input is characterized in that: The parameters of the first continuous wave laser and the third continuous wave laser are the same.

3. According to claim 1, the variable parameter electro-optical delay optical communication system based on double feedback chaotic input is characterized in that: The parameters of the first phase modulator and the second phase modulator are the same.

4. According to claim 1, the variable parameter electro-optical delay optical communication system based on double feedback chaotic input is characterized in that: The coupling coefficients of the first optical coupler, the second optical coupler, the third optical coupler, the fourth optical coupler, the fifth optical coupler and the sixth optical coupler are all 0.

5.

5. According to claim 1, the variable parameter electro-optical delay optical communication system based on double feedback chaotic input is characterized in that: The output signal 2-2-2 of the transmitting end sequentially passes through the standard single-mode optical fiber (11), the erbium-doped optical fiber amplifier (12) and the dispersion compensation optical fiber (13) and enters the receiving end.

6. According to claim 1, the variable parameter electro-optical delay optical communication system based on double feedback chaotic input is characterized in that: The parameters of the first adjustable delay line and the fourth adjustable delay line are the same; the parameters of the second adjustable delay line and the fifth adjustable delay line are the same; the parameters of the third adjustable delay line and the sixth adjustable delay line are the same; the parameters of the first variable optical attenuator and the fifth variable optical attenuator are the same; the parameters of the second variable optical attenuator and the sixth variable optical attenuator are the same; the parameters of the third variable optical attenuator and the seventh variable optical attenuator are the same; the parameters of the fourth variable optical attenuator and the eighth variable optical attenuator are the same.

7. The variable parameter electro-optical delay optical communication system based on double feedback chaotic input according to claim 1, characterized in that: The first photodetector and the third photodetector have the same parameters; the second photodetector and the fourth photodetector have the same parameters; the fifth photodetector and the sixth photodetector have the same parameters; the first RF amplifier and the third RF amplifier have the same parameters; the second RF amplifier and the fourth RF amplifier have the same parameters.

8. The variable-parameter electro-optical delay optical communication system based on double feedback chaotic input according to any one of claims 1 to 7, characterized in that: The parameters of the first Mach-Zehnder modulator and the third Mach-Zehnder modulator are the same.

9. A variable-parameter electro-optical delay optical communication method based on double feedback chaotic input, used to execute the system as claimed in any one of claims 1 to 8, characterized in that: The specific steps of the method are as follows: The first continuous wave laser (1-1) at the transmitting end emits an optical signal, which is fed back to the first continuous wave laser (1-1) after self-phase modulation to generate a double feedback chaotic signal. The signal passes through a third variable optical attenuator (5-3) and serves as the input of a first Mach-Zehnder modulator (10-1), and generates a new chaotic signal through electro-optical delay feedback; a four-level pulse amplitude modulation signal is injected into a second Mach-Zehnder modulator (10-2), and the optical signal emitted by the second continuous wave laser (1-2) is modulated by the second Mach-Zehnder modulator (10-2) to obtain an optical signal, which participates in the electro-optical delay feedback through a third optical coupler (4-3) to achieve signal encryption; The receiving end generates a double feedback chaotic signal, which is used as the input of the third Mach-Zehnder modulator (10-3) after passing through the seventh variable optical attenuator (5-7), and is modulated by the received signal after channel transmission to generate a synchronized chaotic signal. Finally, a subtractor (14) is used to subtract the synchronized chaotic signal and the received signal respectively passing through the fifth photodetector (8-5) and the sixth photodetector (8-6) to achieve decryption.

10. The variable parameter electro-optical delay optical communication method based on double feedback chaotic input according to claim 9, characterized in that: The signal transmission rate is 20Gb / s.

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