All-optical chaotic secret communication system and method based on double F-P interferometer feedback cavity

Abstract

The invention discloses an all-optical chaotic secret communication system and method based on a double F-P interferometer feedback cavity, and the method comprises the following steps: a continuous wave laser generates an optical signal, and the optical signal is processed and transmitted to a first circulator and a second circulator through two single-mode optical fibers; according to the transmitting end, a signal of a first circulator is processed to generate a chaotic signal; an optical signal emitted by the fourth continuous wave laser is processed to obtain a plaintext signal, and the plaintext signal enters the phase modulator after passing through the dispersion element; a chaotic signal returned by the first circulator is divided into two beams, the chaotic signal is processed and converted into an electric signal, the electric signal is amplified and then subjected to chaotic encryption, and an encrypted optical signal is transmitted to a receiving end; and a receiving end generates a synchronous chaotic signal through a structure symmetrical to the transmitting end, filters the synchronous chaotic signal with the same parameter as the transmitting end to generate a synchronous single longitudinal mode chaotic signal, performs phase decryption on the signal and a transmitted encrypted signal in a third phase modulator, and then performs dispersion decryption and secondary phase decryption to obtain the synchronous single longitudinal mode chaotic signal. And finally, original information is recovered.

Description

Technical Field

[0001] This invention belongs to the field of optical information technology and relates to a chaotic secure communication system, specifically an all-optical chaotic secure communication system and method based on a dual FP interferometer feedback cavity. Background Technology

[0002] With the rapid development of information technology, data transmission volume has surged. Globally, 90% of data traffic is transmitted via optical fiber, but the physical layer transmission is largely unprotected, posing a severe challenge to information security. Chaos, as a complex, quasi-random, initial-condition-sensitive, aperiodic, highly nonlinear behavior, exhibits the "butterfly effect"—a small change in initial conditions can lead to a huge difference in outcome. This characteristic makes it naturally suitable for information encryption. Chaotic optical communication injects optical signals into a nonlinear system to generate chaotic encryption signals. Due to the noise-like characteristics of chaos, eavesdroppers cannot obtain useful information from the encrypted signals.

[0003] Currently, although optical chaotic secure communication systems have made significant progress, they still face problems such as insufficient security strength and low information transmission efficiency. To address these challenges, this invention innovatively proposes a chaotic secure communication system design. By introducing a dual Fabry-Perot interferometer feedback structure to generate high-dimensional chaotic signals, and by implementing phase and dispersion joint encryption through multiple channels, the key space is greatly expanded, effectively improving the security of the communication system. Summary of the Invention

[0004] To address the aforementioned problems in existing technologies, this invention proposes an all-optical chaotic secure communication system and method based on a dual-FP interferometer feedback cavity by increasing the complexity of chaotic signals, expanding the key space, and employing a multi-channel phase and dispersion joint encryption method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: An all-optical chaotic secure communication system based on a dual-FP interferometer feedback cavity includes an optical signal generator, a transmitter, and a receiver. The transmitter and receiver are connected via an optical fiber link, as detailed below: At the optical signal generation end, the first optical signal generated by the first continuous wave laser is reflected by the fiber optic reflector and then enters the first optical coupler, which splits it into two optical signals, namely the first optical signal and the second optical signal. At the transmitting end, the fourth continuous wave laser emits a second optical signal that enters the multi-format optical transmitter. The multi-format optical transmitter modulates the original information m(t) into an optical signal to obtain a plaintext signal for subsequent encryption. The plaintext signal enters the first phase modulator through the first dispersive element. The first optical signal is input to the first circulator at the transmitter via the second single-mode fiber, and then sequentially passes through the second continuous-wave laser and the second optical coupler. After passing through the second optical coupler, it is split into two beams, which are respectively fed back by the first and second Fabry-Perot interferometers to generate chaotic signals. The first optical signal returning from the first circulator is split into two beams by the third optical coupler, namely the first-1 beam and the first-2 beam. The first-1 beam passes sequentially through the first tunable optical filter, the first photodetector, and the first radio frequency amplifier before entering the first phase modulator for chaotic encryption. The optical signal output from the first phase modulator passes through the first fiber Bragg grating and then enters the second phase modulator. The first-2 beam passes sequentially through the second tunable optical filter, the second photodetector, and the second radio frequency amplifier before entering the second phase modulator. The optical signal output from the second phase modulator is transmitted through optical fiber to the third phase modulator at the receiver. At the receiving end, the second optical signal is input to the second circulator through the third single-mode fiber, and then sequentially passes through the third continuous-wave laser and the fourth optical coupler. After passing through the fourth optical coupler, it is split into two beams, which generate chaotic signals through the feedback of the third and fourth Fabry-Perot interferometers, respectively. The second optical signal returning through the second circulator is split into two beams by the fifth optical coupler, namely the 2-1 beam and the 2-2 beam. The 2-1 beam passes sequentially through the third tunable optical filter, the third photodetector, and the third RF amplifier before entering the third phase modulator. The optical signal output from the third phase modulator passes through the second fiber Bragg grating before entering the fourth phase modulator. The 2-2 beam passes sequentially through the fourth tunable optical filter, the fourth photodetector, and the fourth RF amplifier before entering the fourth phase modulator. The fourth phase modulator outputs a decryption signal, which is then used by the second dispersive element and the receiver to recover the original information.

[0006] In this invention, the transmitting end comprises three main parts: signal modulation, chaotic signal generation, and chaotic encryption. During signal modulation, a fourth continuous-wave laser emits a second optical signal that enters a multi-format optical transmitter. The multi-format optical transmitter modulates the original information m(t) into an optical signal, obtaining the plaintext signal for subsequent encryption. The plaintext signal, after sufficient inter-symbol overlap is introduced by a first dispersive element, enters a first phase modulator. During chaotic signal generation, a first continuous-wave laser generates a first optical signal, which is reflected by an optical fiber reflector and then enters a first optical coupler, splitting into two optical signals. One beam is transmitted to the transmitting end via a second single-mode fiber, and the other beam is transmitted to the receiving end via a third single-mode fiber. The first optical signal at the transmitting end is input to a first circulator and sequentially passes through a second continuous-wave laser and a second optical coupler. The second optical coupler then generates chaotic signals through feedback from a first Fabry-Perot interferometer and a second Fabry-Perot interferometer. During the chaotic encryption process, the chaotic signal returned by the first circulator is split into two beams by the third optical coupler. The first beam passes through the first tunable optical filter, the first photodetector, and the first radio frequency amplifier in sequence before entering the first phase modulator for chaotic encryption. The encrypted signal passes through the first fiber Bragg grating and is then input into the second phase modulator. The second beam passes through the second tunable optical filter, the second photodetector, and the second radio frequency amplifier in sequence before entering the second phase modulator to complete the entire chaotic encryption process. The output encrypted signal is input into the third phase modulator at the receiving end through an optical fiber.

[0007] The receiver adopts a symmetrical structure to the transmitter, mainly consisting of three parts: synchronous chaotic signal generation, multi-channel chaotic signal generation, and chaotic decryption. In the synchronous chaotic signal generation process, the second optical signal, transmitted through the third single-mode fiber, is input to the second circulator and then sequentially passes through the third continuous-wave laser and the fourth optical coupler. The feedback from the fourth optical coupler, after passing through the third and fourth Fabry-Perot interferometers, generates the synchronous chaotic signal. In the multi-channel chaotic signal generation process, the synchronous chaotic signal returning from the second circulator is split into two beams by the fifth optical coupler. One beam passes sequentially through the third tunable optical filter, the third photodetector, and the third RF amplifier before entering the third phase modulator; the other beam passes sequentially through the fourth tunable optical filter, the fourth photodetector, and the fourth RF amplifier before entering the fourth phase modulator. In the chaotic decryption process, the signal transmitted through the fiber optic link is input to the third phase modulator and then sequentially passes through the second fiber Bragg grating, the fourth phase modulator, and the second dispersive element, finally recovering the original information in the receiver.

[0008] As a preferred embodiment, the parameters of corresponding devices between the transmitting and receiving ends are the same, such as: the parameters of the second and third continuous-wave lasers are the same; the parameters of the first, second, third, fourth, and fifth optical couplers are the same, for example, the coupling coefficient is 0.5; the parameters of the first and third Fabry-Perot interferometers are the same; the parameters of the second and fourth Fabry-Perot interferometers are the same; the parameters of the first and fourth tunable optical filters are the same; the parameters of the second and third tunable optical filters are the same; the parameters of the first and fourth photodetectors are the same; the parameters of the second and third photodetectors are the same; the parameters of the first and fourth RF amplifiers are the same; the parameters of the second and third RF amplifiers are the same; the parameters of the first and second dispersive elements are the same; the parameters of the first and fourth phase modulators are the same; the parameters of the second and third phase modulators are the same; and the parameters of the first and second fiber Bragg gratings are the same.

[0009] As a preferred embodiment, the signal output from the second phase modulator at the transmitting end enters the receiving end sequentially through the first single-mode fiber, the erbium-doped fiber amplifier, and the dispersion compensation fiber.

[0010] In this invention, the common chaotic signal generation process involves a first continuous-wave laser generating a first optical chaotic signal via feedback from an optical fiber reflector. This first chaotic signal serves as the common driving chaotic signal, transmitted to both the transmitter and receiver via single-mode optical fibers. At the transmitter, the chaotic signal generation process involves inputting the first optical chaotic signal into a feedback system consisting of a second continuous-wave laser and two Fabry-Perot interferometers to generate a second optical chaotic signal. The chaotic encryption process involves splitting the second optical chaotic signal into two beams using a third optical coupler. Each beam is filtered through first and second tunable optical filters to produce two single-mode optical chaotic signals, which are then combined with the modulated plaintext information for phase and dispersion encryption. At the receiver, a symmetrical structure is used to generate the same chaotic signal as the transmitter. The received encrypted signal is then compared with the same chaotic signal to complete the decryption process. Finally, the plaintext information is recovered using a dispersive element and a receiver with identical parameters.

[0011] As a preferred option, the coupling coefficient of all couplers is 0.5.

[0012] As a preferred embodiment, the communication system has a signal transmission rate of 40Gb / s.

[0013] This invention also discloses an all-optical chaotic secure communication method based on a dual FP interferometer feedback cavity. Based on the above system, the specific steps of the method are as follows: The optical signal emitted by the first continuous-wave laser undergoes all-optical feedback via an optical fiber reflector to generate a common chaotic signal. At the transmitting end, the common chaotic signal is input to the first circulator and then sequentially passes through the second continuous-wave laser and the second optical coupler. The second optical coupler then generates chaotic signals through feedback from the first and second Fabry-Perot interferometers, respectively. The optical signal emitted by the fourth continuous-wave laser enters a multi-format optical transmitter, which modulates the original information m(t) into an optical signal to obtain the plaintext signal for subsequent encryption. This plaintext signal is then introduced into the first phase modulator after sufficient inter-symbol overlap is introduced by the first dispersive element. The chaotic signal returning from the first circulator is split into two beams by the third optical coupler. Each beam of chaotic signal is filtered by a tunable filter to produce a single-mode chaotic signal. These single-mode chaotic signals are then converted into electrical signals by a photodetector, amplified, and input into the first and second phase modulators for chaotic encryption. Dispersion is introduced between the two phase modulators through a first fiber Bragg grating. In this process, a Fabry-Perot interferometer and a laser diode are introduced to generate a high-dimensional chaotic signal, which enhances the complexity of the chaotic signal. Furthermore, multi-channel encryption is used to achieve joint encryption of phase and dispersion. The device parameters in each module further expand the key space, thereby improving the security of the chaotic communication system.

[0014] At the receiving end, a synchronous chaotic signal is generated by adopting a structure symmetrical with that of the transmitting end. The synchronous chaotic signal is filtered with the same parameters as that of the transmitting end to generate a synchronous single-mode chaotic signal. Then, the synchronous single-mode chaotic signal and the received encrypted signal are used to complete the chaotic decryption in a phase-dispersion structure symmetrical with that of the transmitting end. Finally, the original plaintext information is recovered through the second dispersive element and the receiver.

[0015] The optical signal emitted by the first continuous-wave laser is fed back through an optical fiber reflector, generating a first chaotic signal. At the transmitting end of this invention, the first chaotic optical signal is input into a feedback system consisting of a second continuous-wave laser and two Fabry-Perot interferometers, generating a second chaotic optical signal. The second chaotic optical signal is split into two chaotic optical signals by a third optical coupler, and then passed through first and second tunable filters to become two single-mode chaotic optical signals. The optical signal emitted by the fourth continuous-wave laser enters a multi-format optical transmitter, modulating the original information m(t) into a bright text signal. This signal, after passing through a first dispersive element, undergoes a chaotic encryption operation with the two single-mode chaotic optical signals in a first phase modulator, a first fiber Bragg grating, and a second phase modulator.

[0016] In the receiving end of this invention, a structure symmetrical to that of the transmitting end is used to achieve chaotic decryption. A first optical chaotic signal is input into a feedback system consisting of a third continuous-wave laser and two Fabry-Perot interferometers to generate a synchronous chaotic signal. A tunable filter with the same parameters is used to generate a single-mode chaotic signal identical to that of the transmitting end. This signal, along with the received encrypted signal, is used in a third phase modulator, a second fiber Bragg grating, and a fourth phase modulator for chaotic decryption. Finally, the plaintext information is recovered through a second dispersive element and a receiver.

[0017] Preferably, the signal transmission rate is set to 40Gb / s.

[0018] Compared with the prior art, the beneficial effects of this invention are: This invention discloses an all-optical chaotic secure communication system and method based on a dual FP interferometer feedback cavity. At the transmitting end, the plaintext information m(t) is first modulated by light intensity to obtain a plaintext signal. A high-dimensional chaotic signal is generated by two Fabry-Perot interferometers and a laser diode, which enhances the complexity of the chaotic signal while effectively hiding the time delay characteristics, thereby improving the security of the communication system. The filtered single-mode chaotic signal is used for multi-channel synchronous monitoring of the link, and combined with phase and dispersion joint encryption, which greatly expands the key space, effectively reduces brute-force attacks by illegal eavesdroppers, and significantly improves the security level. Attached Figure Description

[0019] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0020] Figure 1 This is a schematic diagram of the architecture of an all-optical chaotic secure communication system based on a dual FP interferometer feedback cavity, according to a preferred embodiment of the present invention.

[0021] Figure 2 The image shows the time-domain waveform of the plaintext signal input to the transmitter in a preferred embodiment of the present invention, which is based on a dual-FP interferometer feedback cavity in an all-optical chaotic secure communication system design.

[0022] Figure 3 The image shows the time-domain waveform of the plaintext signal decrypted in the design of an all-optical chaotic secure communication system based on a dual-FP interferometer feedback cavity, according to a preferred embodiment of the present invention. Detailed Implementation

[0023] To more clearly illustrate the embodiments of the present invention, specific implementations will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of the present invention. Those skilled in the art can obtain other drawings and other implementations based on these drawings without any creative effort.

[0024] like Figure 1As shown, this embodiment discloses an all-optical chaotic secure communication system based on a dual FP interferometer feedback cavity, comprising an optical signal generator, a transmitter, and a receiver, wherein: The optical signal generating end components include an optical fiber reflector 1, a first continuous wave laser 2-1, and a first optical coupler 3-1. This end is connected to the transmitting end via a second single-mode optical fiber 13-2, and to the receiving end via a third single-mode optical fiber 13-3.

[0025] The transmitting components include a first circulator 4-1, a second continuous wave laser 2-2, a fourth continuous wave laser 2-4, a second optical coupler 3-2, a third optical coupler 3-3, a first Fabry-Perot interferometer 5-1, a second Fabry-Perot interferometer 5-2, a first tunable optical filter 6-1, a second tunable optical filter 6-2, a first photodetector 7-1, a second photodetector 7-2, a first radio frequency amplifier 8-1, a second radio frequency amplifier 8-2, a multi-format optical transmitter 9, a first dispersive element 10-1, a first phase modulator 11-1, a second phase modulator 11-2, and a first fiber Bragg grating 12-1.

[0026] The receiver components include a second circulator 4-2, a third continuous wave laser 2-3, a fourth optical coupler 3-4, a fifth optical coupler 3-5, a third Fabry-Perot interferometer 5-3, a fourth Fabry-Perot interferometer 5-4, a third tunable optical filter 6-3, a fourth tunable optical filter 6-4, a third photodetector 7-3, a fourth photodetector 7-4, a third RF amplifier 8-3, a fourth RF amplifier 8-4, a second dispersive element 10-2, a third phase modulator 11-3, a fourth phase modulator 11-4, a second fiber Bragg grating 12-2, and a receiver 16.

[0027] The transmitter and receiver are connected via a first single-mode fiber 13-1, an erbium-doped fiber amplifier 14, and a dispersion compensation fiber 15.

[0028] The specific connection methods for the above components are as follows: In the optical signal generating end, the first continuous wave laser 2-1 is connected to the input port of the first optical coupler 3-1, the first output port of the first optical coupler 3-1 is connected to the first port of the second single-mode fiber 13-2, and the second output port of the first optical coupler 3-1 is connected to the first port of the third single-mode fiber 13-3.

[0029] In the transmitting end, the second port of the second single-mode fiber 13-2 is connected to the first port of the first circulator 4-1; the second port of the first circulator 4-1 is connected to the input port of the second continuous-wave laser 2-2; the output port of the second continuous-wave laser 2-2 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 input port of the first Fabry-Perot interferometer 5-1; the second output port of the second optical coupler 3-2 is connected to the input port of the second Fabry-Perot interferometer 5-2; the third port of the first circulator 4-1 is connected to the input port of the third optical coupler 3-3; and the first output port of the third optical coupler 3-3 is connected to the input port of the first tunable optical filter 6-1. The output port of the first tunable optical filter 6-1 is connected to the input port of the first photodetector 7-1, the output port of the first photodetector 7-1 is connected to the input port of the first radio frequency amplifier 8-1, and the output port of the first radio frequency amplifier 8-1 is connected to the radio frequency drive port of the first phase modulator 11-1; the second output port of the third optical coupler 3-3 is connected to the input port of the second tunable optical filter 6-2, the output port of the second tunable optical filter 6-2 is connected to the input port of the second photodetector 7-2, the output port of the second photodetector 7-2 is connected to the input port of the second radio frequency amplifier 8-2, and the output port of the second radio frequency amplifier 8-2 is connected to the radio frequency drive port of the second phase modulator 11-2; The fourth continuous wave laser 2-4 is connected to the input port of the multi-format optical transmitter 9. The plaintext information m(t) is input to the electrical signal input port of the multi-format optical transmitter 9. The output port of the multi-format optical transmitter 9 is connected to the input port of the first dispersive element 10-1. The output port of the first dispersive element 10-1 is connected to the input port of the first phase modulator 11-1. The output port of the first phase modulator 11-1 is connected to the input port of the first fiber Bragg grating 12-1. The output port of the first fiber Bragg grating 12-1 is connected to the input port of the second phase modulator 11-2.

[0030] In the common transmission channel, the output port of the second phase modulator 11-2 is connected to the first port of the first single-mode fiber 13-1, the second port of the first single-mode fiber 13-1 is connected to the input port of the erbium-doped fiber amplifier 14, the output port of the erbium-doped fiber amplifier 14 is connected to the first port of the dispersion compensation fiber 15, and the second port of the dispersion compensation fiber 15 is connected to the input port of the third phase modulator 11-3.

[0031] In the receiving end, the second port of the third single-mode fiber 13-3 is connected to the first port of the second circulator 4-2; the second port of the second circulator 4-2 is connected to the input port of the third continuous-wave laser 2-3; the output port of the third continuous-wave laser 2-3 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 input port of the third Fabry-Perot interferometer 5-3; the second output port of the fourth optical coupler 3-4 is connected to the input port of the fourth Fabry-Perot interferometer 5-4; the third port of the second circulator 4-2 is connected to the input port of the fifth optical coupler 3-5; the first output port of the fifth optical coupler 3-5 is connected to the input port of the third tunable optical filter 6-3; the output port of the third tunable optical filter 6-3 is connected to the input port of the third photodetector 7-3; the output port of the third photodetector 7-3 is connected to the input port of the third radio frequency amplifier 8-3; and the third radio frequency amplifier... The output port of 8-3 is connected to the RF drive port of the third phase modulator 11-3; the second output port of the fifth optical coupler 3-5 is connected to the input port of the fourth tunable optical filter 6-4, the output port of the fourth tunable optical filter 6-4 is connected to the input port of the fourth photodetector 7-4, the output port of the fourth photodetector 7-4 is connected to the input port of the fourth RF amplifier 8-4, and the output port of the fourth RF amplifier 8-4 is connected to the RF drive port of the fourth phase modulator 11-4; the output port of the third phase modulator 11-3 is connected to the input port of the second fiber Bragg grating 12-2, the output port of the second fiber Bragg grating 12-2 is connected to the input port of the fourth phase modulator 11-4, the output port of the fourth phase modulator 11-4 is connected to the input port of the second dispersive element 10-2, and the output port of the second dispersive element 10-2 is connected to the input port of the receiver 16, finally obtaining the decrypted signal m'(t).

[0032] In this embodiment, the coupling coefficient of all couplers is 0.5.

[0033] In this embodiment, the parameters of the corresponding devices between the transmitter and receiver are the same.

[0034] This embodiment presents an all-optical chaotic secure communication system based on a dual FP interferometer feedback cavity. The signal encryption and decryption principle is briefly described below: The optical signal emitted by the first continuous-wave laser is first fed back through an optical fiber reflector to generate a first chaotic signal as a common chaotic signal. This common signal is used to drive the synchronization of signals at the transmitting and receiving ends. At the transmitting end, the optical signal emitted by the fourth continuous-wave laser is modulated by optical intensity to obtain a plaintext signal for optical chaotic encryption. This plaintext signal is then used for effective encryption by introducing sufficient inter-symbol overlap through a first dispersive element. The common chaotic signal is transmitted to the transmitting end through a second single-mode fiber. A complex chaotic signal is generated by combining all-optical feedback and optical injection methods. Time delay feature hiding is then used to generate a second chaotic signal. This signal is split into two channels by a second optical coupler. Each channel is filtered by its own tunable optical filter to obtain a single-mode chaotic signal, which is used for phase encryption. The processed plaintext information and the single-mode chaotic signal are first phase-encrypted by a feedback cavity structure formed by a first phase-modulated double Fabry-Perot interferometer, then dispersion-encrypted by a first fiber Bragg grating, and finally phase-encrypted again by a second phase modulator, completing the entire chaotic encryption process. In this process, the dual-laser feedback structure provides a sufficiently complex chaotic signal, and the dual Fabry-Perot interferometer feedback cavity enhances the complexity of the chaotic signal while effectively hiding time delay information; wavelength selection combined with phase and dispersion dual encryption further improves the security of the communication system.

[0035] At the receiving end, a structure symmetrical to that at the transmitting end is used to achieve chaotic decryption. First, a common chaotic signal is used to generate chaos identical to the second chaotic signal; then, a synchronized chaotic signal is generated using the same single-mode chaotic signal as at the transmitting end; this signal is used to perform chaotic decryption with the received encrypted signal, and finally, the plaintext information is recovered through the second dispersive element and the receiver.

[0036] The communication process of an all-optical chaotic secure communication system based on a dual-FP interferometer feedback cavity, as described in this embodiment, is briefly described below: 1. By setting parameters, the all-optical feedback chaos is used as a common chaotic signal. The high-dimensional chaotic signal is generated by optical injection combined with a double Fabry-Perot interferometer to form a feedback cavity structure and used as a chaotic carrier. On this basis, the single-mode chaotic signal is filtered out and participates in phase-dispersion dual encryption together with the plaintext information. While increasing the complexity of the chaotic signal, the key space is greatly expanded.

[0037] 2. Plaintext signals are encrypted using chaotic masking.

[0038] 3. The receiver adopts a symmetrical structure with the transmitter. First, it uses a common chaotic signal to generate the same double-feedback chaotic signal. Then, it uses the same wavelength combination as the transmitter to generate a synchronous single-mode chaotic signal. After chaotic decryption, the plaintext information is recovered through the second dispersive element and the receiver.

[0039] This invention discloses an all-optical chaotic secure communication system and method based on a dual Fabry-Perot interferometer feedback cavity. In the system, the light from a first laser is fed back through an optical fiber reflector and then split into two beams by a first optical coupler, which are transmitted to the transmitter and receiver respectively via optical fibers. At the transmitter, the all-optical feedback signal is injected into the feedback cavity composed of a second laser and a dual Fabry-Perot interferometer. This optical signal is split into two beams by a third optical coupler, and each beam passes through a tunable optical filter, a photodetector, and an RF amplifier before being input into a phase modulator. The optical text signal passes through a first dispersive element and is then input into the phase modulator and a fiber Bragg grating. After encryption, the output signal is used for channel transmission. At the receiver, the all-optical feedback signal is injected into the feedback cavity composed of a third laser and a dual Fabry-Perot interferometer. This optical signal is split into two beams by a fifth optical coupler, and each beam passes through a tunable optical filter, a photodetector, and an RF amplifier before being input into the phase modulator. The phase and dispersion modulated light transmitted through the channel are then output and passed through a dispersive element and a receiver.

[0040] The above are preferred embodiments of the present invention and do not limit the scope of protection of the present invention. For those skilled in the art, 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 considered within the scope of protection of the present invention.

Claims

1. A fully optical chaotic secure communication system based on a dual FP interferometer feedback cavity, comprising an optical signal generating end, a transmitting end, and a receiving end, characterized in that: At the optical signal generation end, the first optical signal generated by the first continuous wave laser (2-1) is reflected by the fiber optic reflector (1) and enters the first optical coupler (3-1) to be divided into two optical signals, namely the first optical signal and the second optical signal. At the transmitting end, the fourth continuous wave laser (2-4) emits a second optical signal into the multi-format optical transmitter (9). The original information m(t) is modulated into an optical signal by the multi-format optical transmitter (9) to obtain a plaintext signal for encryption. The plaintext signal enters the first phase modulator (11-1) through the first dispersive element (10-1). The first optical signal is input to the first circulator (4-1) at the transmitter through the second single-mode fiber (13-2), and then splits into two beams after passing through the second continuous-wave laser (2-2) and the second optical coupler (3-2). These beams are then fed back by the first Fabry-Perot interferometer (5-1) and the second Fabry-Perot interferometer (5-2), respectively, generating chaotic signals. The first optical signal returning from the first circulator (4-1) is split into two beams by the third optical coupler (3-3), namely the first-1 optical signal and the first-2 optical signal. The first-1 optical signal passes through the first tunable optical filter (6-1) and the first photoelectric... After passing through the detector (7-1) and the first radio frequency amplifier (8-1), the optical signal enters the first phase modulator (11-1) for chaotic encryption. The optical signal output from the first phase modulator (11-1) passes through the first fiber Bragg grating (12-1) and then enters the second phase modulator (11-2). The first and second optical signals pass through the second tunable optical filter (6-2), the second photodetector (7-2), and the second radio frequency amplifier (8-2) in sequence before entering the second phase modulator (11-2). The optical signal output from the second phase modulator (11-2) is transmitted through optical fiber to the third phase modulator (11-3) at the receiving end. At the receiving end, the second optical signal is input to the second circulator (4-2) through the third single-mode fiber (13-3), and then split into two beams after passing through the third continuous-wave laser (2-3) and the fourth optical coupler (3-4). These beams are then fed back by the third Fabry-Perot interferometer (5-3) and the fourth Fabry-Perot interferometer (5-4), respectively, generating chaotic signals. The second optical signal returning through the second circulator (4-2) is split into two beams by the fifth optical coupler (3-5), namely the 2-1 optical signal and the 2-2 optical signal. The 2-1 optical signal passes through the third tunable optical filter (6-3) and the third optoelectronic... After passing through the detector (7-3) and the third radio frequency amplifier (8-3), the light signal enters the third phase modulator (11-3). The light signal output by the third phase modulator (11-3) passes through the second fiber Bragg grating (12-2) and then enters the fourth phase modulator (11-4). The second-second light signal passes through the fourth tunable optical filter (6-4), the fourth photodetector (7-4), and the fourth radio frequency amplifier (8-4) in sequence and then enters the fourth phase modulator (11-4). The fourth phase modulator (11-4) outputs a decryption signal, which is then processed by the second dispersive element (10-2) and the receiver (16) to recover the original information.

2. The all-optical chaotic secure communication system based on a dual FP interferometer feedback cavity according to claim 1, characterized in that, The parameters of the second and third continuous wave lasers are the same.

3. The all-optical chaotic secure communication system based on a dual FP interferometer feedback cavity according to claim 1, characterized in that, The parameters of the first phase modulator and the fourth phase modulator are the same, and the parameters of the second phase modulator and the third phase modulator are the same.

4. The all-optical chaotic secure communication system based on a dual FP interferometer feedback cavity according to claim 1, characterized in that, The coupling coefficients of the first, second, third, fourth, and fifth optical couplers are all 0.

5.

5. The all-optical chaotic secure communication system based on a dual FP interferometer feedback cavity according to claim 1, characterized in that, The first and third Fabry-Perot interferometers have the same parameters, as do the second and fourth Fabry-Perot interferometers.

6. The all-optical chaotic secure communication system based on a dual FP interferometer feedback cavity according to claim 1, characterized in that, The parameters of the first dispersive element and the second dispersive element are the same.

7. The all-optical chaotic secure communication system based on a dual FP interferometer feedback cavity according to claim 1, characterized in that, The first and fourth tunable optical filters have the same parameters, and the second and third tunable optical filters have the same parameters.

8. The all-optical chaotic secure communication system based on a dual FP interferometer feedback cavity according to claim 1, characterized in that, The parameters of the first photodetector and the fourth photodetector are the same, and the parameters of the second photodetector and the third photodetector are the same. And / or, the parameters of the first RF amplifier and the fourth RF amplifier are the same, and the parameters of the second RF amplifier and the third RF amplifier are the same; And / or, the parameters of the first fiber Bragg grating and the second fiber Bragg grating are the same.

9. A fully optical chaotic secure communication system based on a dual FP interferometer feedback cavity according to any one of claims 1-8, characterized in that, The signal output from the second phase modulator at the transmitter enters the receiver sequentially through the first single-mode fiber (13-1), the erbium-doped fiber amplifier (14), and the dispersion compensation fiber (15).

10. A method for all-optical chaotic secure communication based on a dual FP interferometer feedback cavity, based on the system described in any one of claims 1-9, characterized in that, The specific steps of the method are as follows: The first continuous wave laser (2-1) generates a first optical signal, which is reflected by the fiber reflector (1) and enters the first optical coupler (3-1) to be split into two optical signals. The signals are transmitted to the first circulator (4-1) at the transmitting end and the second circulator (4-2) at the receiving end through the second single-mode fiber (13-2) and the third single-mode fiber (13-3), respectively. At the transmitting end, the signal input to the first circulator (4-1) is split into two beams after passing through the second continuous-wave laser (2-2) and the second optical coupler (3-2). These beams are then fed back by the first Fabry-Perot interferometer (5-1) and the second Fabry-Perot interferometer (5-2) to generate chaotic signals. The optical signal emitted by the fourth continuous-wave laser (2-4) enters the multi-format optical transmitter (9), which modulates the original information m(t) into an optical signal to obtain the plaintext signal used for encryption. The plaintext signal passes through the first dispersive element (10-1) and then enters the second circulator. A phase modulator (11-1) is used. The chaotic signal returned by the first circulator (4-1) is split into two beams by the third optical coupler (3-3). Each chaotic signal is filtered out by a tunable optical filter to produce a single-mode chaotic signal. The single-mode chaotic signal is then converted into an electrical signal by a photodetector and amplified by an RF amplifier. The signal is then input to the first phase modulator (11-1) and the second phase modulator (11-2) for chaotic encryption. Dispersion is introduced between the two phase modulators by a first fiber Bragg grating (12-1). The encrypted optical signal is transmitted through the optical fiber to the receiving end. At the receiving end, a synchronous chaotic signal is generated by a structure symmetrical to that of the transmitting end. The synchronous chaotic signal is filtered with the same parameters as that of the transmitting end to generate a synchronous single-mode chaotic signal. This signal and the transmitted encrypted signal are used together in the third phase modulator (11-3) for the first phase decryption. Then, it is input to the second fiber Bragg grating (12-2) for dispersion decryption. Subsequently, it is used in the fourth phase modulator for the second phase decryption. Finally, the original information is recovered through the second dispersion element (10-2) and the receiver (16).

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