Optical frequency hopping encryption communication system based on time delay interferometer

Abstract

The present disclosure provides a kind of optical frequency hopping encryption communication system based on delay interferometer, system includes transmitter.The transmitter includes: laser generation module, for generating carrier signal, wherein the carrier signal includes the continuous wave laser of first fixed wavelength and second fixed wavelength;Phase modulation and delay interference module, for processing carrier signal according to control sequence, respectively generate first carrier signal and second carrier signal, wherein the first carrier signal and the second carrier signal each include the non-continuous laser of first fixed wavelength and second fixed wavelength alternately appear, and at the same time, the wavelength of first carrier signal is different from the wavelength of second carrier signal;And signal modulation and emission module, for modulating first carrier signal with first to-be-transmitted signal to generate first sending signal;Also for modulating second carrier signal with second to-be-transmitted signal to generate second sending signal, and first sending signal and second sending signal are coupled and sent.

Description

Technical Field

[0001] This disclosure relates to the field of optical fiber communication security, and in particular to an optical frequency hopping encrypted communication system based on a time delay interferometer. Background Technology

[0002] With the rapid development of fiber optic communication technology, the probability of user information leaks has increased, and the risk of user data being illegally stolen by third parties during transmission is growing. Therefore, optical communication security technology is receiving increasing attention. In existing secure communication mechanisms, encrypting user data using algorithms at the software layer is the most common method. However, with the improvement of computing power, the security of this method is gradually decreasing. Therefore, it is necessary to develop secure communication technologies from other aspects. Summary of the Invention

[0003] In view of this, the main objective of this disclosure is to provide an optical frequency hopping encrypted communication system based on a time-delay interferometer, in order to partially solve at least one of the aforementioned technical problems.

[0004] To achieve the above objectives, one aspect of this disclosure provides a transmitter, comprising:

[0005] A laser generation module is used to generate a carrier signal, wherein the carrier signal includes a continuous wave laser with a first fixed wavelength and a second fixed wavelength; a phase modulation and delay interference module is used to process the carrier signal according to a control sequence to generate a first carrier signal and a second carrier signal respectively, wherein the control sequence is a pseudo-random binary array generated based on a preset seed source, wherein the first carrier signal and the second carrier signal each include a discontinuous laser with alternating first and second fixed wavelengths, and at the same time, the wavelength of the first carrier signal is different from the wavelength of the second carrier signal; and a signal modulation and transmission module is used to modulate the first carrier signal with a first signal to be transmitted to generate a first transmission signal; and is also used to modulate the second carrier signal with a second signal to be transmitted to generate a second transmission signal, and couple the first transmission signal and the second transmission signal for transmission, wherein the first signal to be transmitted and the second signal to be transmitted are two complementary signals formed according to preset data to be transmitted.

[0006] According to an embodiment of this disclosure, the phase modulation and delay interference module includes: a radio frequency signal generation module, a first modulation submodule, and a second modulation submodule; wherein, the radio frequency signal generation module is used to generate a control radio frequency signal and a reverse control radio frequency signal according to a control sequence; the first modulation submodule is used to generate a first carrier signal according to the control radio frequency signal and the carrier signal; and the second modulation submodule is used to generate a second carrier signal according to the reverse control radio frequency signal and the carrier signal.

[0007] According to embodiments of this disclosure, the radio frequency signal generation module includes a pseudo-random sequence generator, an inverter, and a differential encoder; the pseudo-random sequence generator is used to generate a control sequence based on a preset seed source and divide the control sequence into a first control sequence and a second control sequence; the inverter is used to receive the first control sequence and generate an inverse control sequence; the differential encoder is used to generate a control radio frequency signal based on the second control sequence and also to generate an inverse control radio frequency signal based on the inverse control sequence; the first modulation submodule includes a first modulator and a first delay interferometer; the first modulator is used to perform phase modulation on the carrier signal based on the control radio frequency signal. The system generates a first modulated carrier signal, wherein the phase of the first modulated carrier signal remains constant or changes by π according to the control radio frequency signal; the first delay interferometer is used to perform delay interferometry on the first modulated carrier signal to generate a first carrier signal; the second modulation submodule includes a second modulator and a second delay interferometer; the second modulator is used to perform phase modulation on the carrier signal according to the reverse control radio frequency signal to generate a second modulated carrier signal, wherein the phase of the second modulated carrier signal remains constant or changes by π according to the reverse control radio frequency signal; the second delay interferometer is used to perform delay interferometry on the second modulated carrier signal to generate a second carrier signal.

[0008] According to an embodiment of this disclosure, the laser generation module includes: a laser generation submodule and a first coupler group; the laser generation submodule is used to generate a first frequency laser and a second frequency laser; the first coupler group is used to receive the first frequency laser and the second frequency laser and generate a carrier signal.

[0009] According to embodiments of this disclosure, the signal modulation and transmission module includes:

[0010] A first Mach-Zehnder modulator, a second Mach-Zehnder modulator, and a coupler; the first Mach-Zehnder modulator is used to modulate the first carrier signal with the first signal to be transmitted to generate a first transmit signal; the second Mach-Zehnder modulator is used to modulate the second carrier signal with the second signal to be transmitted to generate a second transmit signal; and the coupler couples the first transmit signal and the second transmit signal and outputs the coupled first transmit signal and the second transmit signal.

[0011] Another aspect of this disclosure provides a receiver, comprising:

[0012] The system includes a demodulated signal generation module for generating a first demodulated signal and a second demodulated signal based on a coupled first transmitted signal and a second transmitted signal; a demodulation module for processing the first demodulated signal and the second demodulated signal according to the control sequence to generate a first decrypted signal and a second decrypted signal, wherein the control sequence is a pseudo-random binary array generated based on a preset seed source, and the first decrypted signal and the second decrypted signal each include a discontinuous laser with alternating first and second fixed wavelengths, and at the same time, the wavelength of the first decrypted signal is different from the wavelength of the second decrypted signal; and a signal detection module for obtaining a first signal to be transmitted carried on the first decrypted signal based on the first decrypted signal, and also for obtaining a second signal to be transmitted carried on the second decrypted signal based on the second decrypted signal, wherein the first signal to be transmitted and the second signal to be transmitted are two complementary signals formed based on preset data to be transmitted.

[0013] According to an embodiment of this disclosure, the demodulated signal generation module includes a wavelength demultiplexer; the wavelength demultiplexer is used to receive a coupled first transmission signal and a second transmission signal emitted by a transmitting station, and to generate the first demodulated signal and the second demodulated signal based on the coupled first transmission signal and the second transmission signal.

[0014] According to embodiments of this disclosure, the demodulation module includes:

[0015] A pseudo-random sequence generator and a 2×2 optical switch; the pseudo-random sequence generator is used to generate the control sequence; the 2×2 optical switch is used to generate the first decryption signal and the second decryption signal based on the control sequence and the first demodulated signal and the second demodulated signal.

[0016] Another aspect of this disclosure provides an optical frequency hopping encrypted communication system based on a time-delay interferometer, comprising:

[0017] A transmitter is configured to process a carrier signal according to a control sequence, generate a first carrier signal and a second carrier signal respectively, and modulate a first signal to be transmitted with the first carrier signal to generate a first transmit signal, modulate a second signal to be transmitted with the second carrier signal to generate a second transmit signal, and output the first transmit signal and the second transmit signal after coupling them together. The control sequence is a pseudo-random binary array generated based on a preset seed source, and the first signal to be transmitted and the second signal to be transmitted are two complementary signals formed based on preset data to be transmitted. A receiver is configured to generate two identical demodulated signals based on the coupled first and second transmit signals, process the demodulated signals according to the same control sequence as the transmitter, generate a first decrypted signal and a second decrypted signal respectively, generate a first transmit signal based on the first decrypted signal, and generate a second transmit signal based on the second decrypted signal.

[0018] According to embodiments of this disclosure, the above-described optical frequency hopping encrypted communication system further includes:

[0019] The receiver transmits the coupled first and second transmission signals to the transmitter via an optical fiber; an optical fiber amplifier is provided in front of the receiver port of the transmitter to amplify the coupled first and second transmission signals.

[0020] Based on the above technical solutions, it can be seen that the embodiments of this disclosure have the following beneficial effects compared with the prior art:

[0021] By modulating the first and second signals to be transmitted, obtained from the data to be transmitted, onto the first and second carrier signals respectively, it is possible to achieve random switching of the preset data to be transmitted between channels corresponding to different wavelengths, thereby preventing information leakage and illegal eavesdropping. Attached Figure Description

[0022] Figure 1 A schematic diagram of the frame of a transmitter according to an embodiment of the present disclosure is shown.

[0023] Figure 2 A schematic diagram of the frame of a receiver according to an embodiment of the present disclosure is shown.

[0024] Figure 3 The schematic diagram illustrates a framework of an optical frequency-hopping encrypted communication system based on a time-delay interferometer according to an embodiment of the present disclosure;

[0025] Figure 4 The diagram illustrates the phase modulation and time-delay interference principle of an optical frequency hopping encrypted communication system based on a time-delay interferometer according to an embodiment of the present disclosure.

[0026] Figure 5The illustration schematically shows a laser frequency jump in the first and second carrier signals of an optical frequency hopping encrypted communication system based on a time-delay interferometer according to an embodiment of the present disclosure;

[0027] Figure 6 The illustration schematically shows a data hopping diagram in a receiver of an optical frequency hopping encrypted communication system based on a time-delay interferometer according to an embodiment of the present disclosure. Detailed Implementation

[0028] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0029] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0030] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0031] When using expressions such as "at least one of A, B, and C", they should generally be interpreted in accordance with the meaning that is commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B, and C, etc.).

[0032] In existing secure communication mechanisms, the security of software-layer algorithms for encrypting user data begins to decrease with increasing computing power. Therefore, current research has gradually shifted towards physical layer security technologies. Physical layer security technologies utilize the physical characteristics of communication channels to enhance communication security through appropriate signal encoding and processing. Optical frequency hopping is one such physical layer security technology, primarily achieving data concealment by hopping digital signals between different channels.

[0033] In realizing the concept of this disclosure, the inventors discovered at least the following problems in the related technology:

[0034] In the process of achieving random switching of user data between channels corresponding to different wavelengths using optical frequency hopping, it is necessary to process the carrier signal to enable the digital signal to switch between different channels. Existing technologies have complex structures in the devices used by the transmitter to process the carrier signal and the corresponding devices used by the receiver to demodulate the signal, which is not conducive to the use of optical frequency hopping encrypted communication systems in practical scenarios.

[0035] In order to at least partially solve the technical problems existing in the related art, one aspect of this disclosure provides a transmitter.

[0036] Figure 1 A schematic diagram of the frame of a transmitter according to an embodiment of the present disclosure is shown.

[0037] like Figure 1 As shown, the transmitter includes:

[0038] The laser generation module 110 is used to generate a carrier signal, wherein the carrier signal includes a continuous wave laser with a first fixed wavelength and a second fixed wavelength.

[0039] The phase modulation and delay interference module 120 is used to process the carrier signal according to the control sequence and generate a first carrier signal and a second carrier signal respectively. The control sequence is a pseudo-random binary array generated based on a preset seed source. The first carrier signal and the second carrier signal each include a discontinuous laser with alternating first and second fixed wavelengths. At the same time, the wavelength of the first carrier signal is different from the wavelength of the second carrier signal.

[0040] The system also includes a signal modulation and transmission module 130, which modulates the first carrier signal and the first signal to be transmitted to generate a first transmission signal; and modulates the second carrier signal and the second signal to be transmitted to generate a second transmission signal, and couples the first transmission signal and the second transmission signal for transmission, wherein the first signal to be transmitted and the second signal to be transmitted are two complementary signals formed according to preset data to be transmitted.

[0041] According to an embodiment of the present disclosure, a first fixed wavelength continuous wave laser and a second fixed wavelength continuous wave laser are generated by the laser generation module 110, and the first fixed wavelength continuous wave laser and the second fixed wavelength continuous wave laser are input into the phase modulation and delay interference module 120.

[0042] According to embodiments of this disclosure, in the phase modulation and delay interference module 120, phase modulation and delay interference processing are simultaneously performed on a first fixed-wavelength continuous-wave laser and a second fixed-wavelength continuous-wave laser according to a control sequence. The phase change of the first and second fixed-wavelength continuous-wave lasers is controlled by "1" or "0" in the pseudo-random binary array of the control sequence. Then, delay interference processing is performed on the phase-modulated first and second fixed-wavelength continuous-wave lasers, causing a portion of the phase-modulated first fixed-wavelength continuous-wave laser to undergo constructive interference, which is retained in the phase modulation and delay interference module 120; another portion undergoes destructive interference and is not retained. The same processing is performed on the phase-modulated second fixed-wavelength continuous-wave laser to obtain a first carrier signal and a second carrier signal.

[0043] According to embodiments of this disclosure, a pseudo-random binary array is a cyclic array that resembles a random array but actually exhibits a period, generated based on a preset seed source. The seed value of the preset seed source controls the first value generated by the formula for generating the pseudo-random array. Since the formula is fixed, setting the seed value sets the entire sequence to be generated. The seed value can be a specific random source used by default. If there is no random source, the current time can be used as the seed value.

[0044] According to embodiments of this disclosure, in the signal modulation and transmission module 130, a first carrier signal is modulated with a first signal to be transmitted to generate a first transmission signal; a second carrier signal is modulated with a second signal to be transmitted to generate a second transmission signal. Specifically, a preset data to be transmitted can be divided according to a preset interval to obtain multiple non-overlapping data segments, which are then divided into two groups as the first signal to be transmitted and the second signal to be transmitted. The grouping of data segments can be based on a preset interval node, with the data segments before this node serving as the first signal to be transmitted, and the data segments before and after this node serving as the second signal to be transmitted. Alternatively, the data segments can be divided into two groups according to a preset order.

[0045] Another aspect of this disclosure provides a transmitter.

[0046] Figure 2 A schematic diagram of the frame of a receiver according to an embodiment of the present disclosure is shown.

[0047] like Figure 2 As shown, the receiver includes:

[0048] The demodulated signal generation module 210 is used to generate a first demodulated signal and a second demodulated signal based on the received coupled first and second transmitted signals.

[0049] The demodulation module 220 is used to process the first demodulated signal and the second demodulated signal according to the control sequence to generate the first decrypted signal and the second decrypted signal. The control sequence is a pseudo-random binary array generated based on a preset seed source. The first decrypted signal and the second decrypted signal each include a discontinuous laser with alternating first and second fixed wavelengths. At the same time, the wavelength of the first decrypted signal is different from the wavelength of the second decrypted signal.

[0050] And a signal detection module 230, used to obtain a first signal to be transmitted carried on the first decryption signal according to the first decryption signal, and also used to obtain a second signal to be transmitted carried on the second decryption signal according to the second decryption signal, wherein the first signal to be transmitted and the second signal to be transmitted are two complementary signals formed according to preset data to be transmitted.

[0051] According to an embodiment of this disclosure, the demodulation signal generation module 210 demodulates the first and second transmitted signals coupled from the transmitter to obtain a first fixed wavelength and a second fixed wavelength continuous wave laser. Due to the modulation of the transmitter's phase modulation and delay interference module and signal modulation and transmission module, the first fixed wavelength continuous wave laser and the second fixed wavelength continuous wave laser obtained by the receiver's demodulation signal generation module are each modulated with an alternating first and second transmitted signals. At the same time, the first fixed wavelength continuous wave laser and the second fixed wavelength continuous wave laser are modulated with different signals.

[0052] According to embodiments of this disclosure, the control sequence in demodulation module 220 is a control sequence obtained based on the same preset seed source as in the corresponding transmitter.

[0053] According to an embodiment of this disclosure, after the signal detection module 230 obtains the first signal to be transmitted and the second signal to be transmitted, it can directly output the signal to be transmitted to an external device for processing. According to the grouping method of dividing the data to be transmitted into the first signal to be transmitted and the second signal to be transmitted in the transmitter, a corresponding data recovery method is obtained.

[0054] The following is for reference. Figures 3-6 The optical frequency hopping encrypted communication system based on a time delay interferometer will be further explained with reference to specific embodiments.

[0055] Figure 3 The diagram illustrates a framework of an optical frequency-hopping encrypted communication system based on a time-delay interferometer according to an embodiment of the present disclosure.

[0056] like Figure 3 As shown, the optical frequency hopping encrypted communication system based on a time-delay interferometer includes:

[0057] Transmitter 310 is configured to process carrier signals according to a control sequence, generate a first carrier signal and a second carrier signal respectively, and modulate a first signal to be transmitted with the first carrier signal to generate a first transmit signal, modulate a second signal to be transmitted with the second carrier signal to generate a second transmit signal, and output the first transmit signal and the second transmit signal after coupling. The control sequence is a pseudo-random binary array generated based on a preset seed source, and the first signal to be transmitted and the second signal to be transmitted are two complementary signals formed based on preset data to be transmitted. Receiver 320 is configured to generate two identical demodulated signals based on the coupled first and second transmit signals, process the demodulated signals according to the same control sequence as the transmitter, generate a first decrypted signal and a second decrypted signal respectively, generate a first transmit signal based on the first decrypted signal, and generate a second transmit signal based on the second decrypted signal.

[0058] According to embodiments of this disclosure, the transmitter 310 includes a laser generation module 311, a phase modulation and delay interference module 312, and a signal modulation and transmission module 313. The functions of the laser generation module 311, the phase modulation and delay interference module 312, and the signal modulation and transmission module 313 are the same as those of the laser generation module 110, the phase modulation and delay interference module 120, and the signal modulation and transmission module 313 described above, and will not be repeated here.

[0059] According to an embodiment of this disclosure, the receiver 320 includes a signal generation module 321 to be demodulated, a demodulation module 322, and a signal detection module 323. The signal generation module 321, demodulation module 322, and signal detection module 323 have the same functions as the signal generation module 210, demodulation module 220, and signal detection module 230 described above, and will not be repeated here.

[0060] According to an embodiment of this disclosure, the laser generation module 311 includes a laser generation submodule and a first coupler group.

[0061] More specifically, the laser generation submodule may include a first continuous-wave laser and a second continuous-wave laser. The first continuous-wave laser is used to generate a first fixed-wavelength laser, and the second continuous-wave laser is used to generate a second fixed-wavelength laser.

[0062] More specifically, the first coupler group may include coupler 1 and coupler 2. Coupler 1 is used to receive a first fixed-wavelength laser and a second fixed-wavelength laser, and couple them together before sending them to coupler 2. Coupler 2 is used to split the coupled first fixed-wavelength laser and the second fixed-wavelength laser into two identical carrier signals. The carrier signals include continuous-wave lasers of the first and second fixed wavelengths.

[0063] According to embodiments of this disclosure, the phase modulation and delay interference module 312 includes: a radio frequency signal generation module, a first modulation submodule, and a second modulation submodule.

[0064] The radio frequency signal generation module is used to generate control radio frequency signals and reverse control radio frequency signals according to the control sequence.

[0065] More specifically, the radio frequency signal generation module may include a differential encoder, a pseudo-random number generator (PRNG), and an inverter. The PRNG generates a control sequence based on a preset seed source and outputs a first control sequence and a second control sequence. The inverter receives the first control sequence and generates an inverse control sequence. The differential encoder generates a control radio frequency signal based on the second control sequence and also generates an inverse control radio frequency signal based on the inverse control sequence.

[0066] The first modulation submodule is used to generate a first carrier signal based on the control radio frequency signal and the carrier signal. The second modulation submodule is used to generate a second carrier signal based on the reverse control radio frequency signal and the carrier signal.

[0067] More specifically, the first modulation submodule includes a first modulator and a first delay interferometer. The first modulator receives a control radio frequency signal and modulates the first carrier signal sent from the laser generation module 311 to the first modulator according to the "1" or "0" of the binary array in the control radio frequency signal, thereby changing the phase of the first fixed wavelength and the second fixed wavelength continuous wave laser in the first carrier signal. The second modulation submodule receives a reverse control radio frequency signal and generates a second carrier signal through the same operation described above.

[0068] More specifically, the modulators used in the embodiments of this disclosure can all be phase modulators (PM).

[0069] Figure 4 The diagram illustrates the phase modulation and time-delay interference principle of an optical frequency hopping encrypted communication system based on a time-delay interferometer according to an embodiment of the present disclosure.

[0070] like Figure 4As shown in part (a), the first carrier signal sent from the laser generation module 311 to the first modulator includes a first fixed-wavelength continuous-wave laser λ1 and a second fixed-wavelength continuous-wave laser λ2. The first fixed-wavelength continuous-wave laser corresponds to a first frequency f1, and the second fixed-wavelength continuous-wave laser corresponds to a second frequency f2. The input optical signal E at point a... in(i) It can be expressed by the following formula (1):

[0071]

[0072] Among them, E c(i) Let c be the maximum energy of either the first fixed-wavelength or the second fixed-wavelength continuous-wavelength laser at time c. Let i be the phase of the first fixed wavelength continuous wave laser or the second fixed wavelength continuous wave laser at time c, where i = 1 or 2, corresponding to the first fixed wavelength continuous wave laser or the second fixed wavelength continuous wave laser.

[0073] The first modulator in the first modulation submodule modulates E according to the control radio frequency signal. in(i) Modulation is performed, E in(i) After passing through the phase modulator, its phase can remain unchanged or change by π. The modulation process can be represented by the following formula (2):

[0074]

[0075] Where E out(i) The first or second modulated carrier signal at point b. e is the modulation phase of the first or second modulated carrier signal. jRπ R is the modulation phase change of the first or second modulation carrier signal, and R is the binary value in the control radio frequency signal or the reverse control radio frequency signal, where R = 1 or 0.

[0076] When R = 1, the phase of the first fixed wavelength continuous wave laser or the second fixed wavelength continuous wave laser changes by π; when R = 0, the phase of the first fixed wavelength continuous wave laser or the second fixed wavelength continuous wave laser remains unchanged.

[0077] The first modulated carrier signal is input into the first delay interferometer. The first modulated carrier signal is divided into two paths and passes through the upper and lower arms of the first delay interferometer. The upper and lower arms delay the two paths of the first modulated carrier signal by different times, introducing an optical path difference between the two paths of the first modulated carrier signal. The process of introducing the optical path difference can be represented by the following formula (3):

[0078]

[0079] Where, Δ upperFor the time delay of the upper arm, Δ lower Let λ(i) be the time delay of the lower arm, λ(i) be the first fixed wavelength continuous wave laser or the second fixed wavelength continuous wave laser, ΔT be the time delay of the two paths of the first delay interferometer, and c be the speed of light.

[0080] Figure 4 (b) shows the frequency response curves of the delay interferometer for different frequency light waves. The solid line represents the frequency response curve of the first fixed-wavelength continuous-wave laser, and the dashed line represents the frequency response curve of the second fixed-wavelength continuous-wave laser. The first and second fixed-wavelength continuous-wave lasers periodically exhibit maximum and minimum values ​​in their frequency response curves based on the phase change when entering the first delay interferometer. The parameters of the laser generation submodule can be adjusted so that the first fixed-wavelength laser generated by the laser generation module 311 is at the minimum value of the frequency response curve, and the second fixed-wavelength laser is at the maximum value of the frequency response curve. That is, the frequency difference between the two fixed wavelengths satisfies the condition of the following equation (4):

[0081]

[0082] Where m can be any positive integer.

[0083] For the second fixed-wavelength laser at the maximum value of the frequency response curve, the light wave after passing through the upper and lower arms of the first delay interferometer undergoes "constructive interference," meaning that the phase changes introduced by the upper and lower arms of the first delay interferometer differ by an integer multiple of 2π. For the first fixed-wavelength laser at the minimum value of the frequency response curve, the light wave after passing through the upper and lower arms of the first delay interferometer undergoes "destructive interference," meaning that the phase changes introduced by the upper and lower arms differ by an odd multiple of π.

[0084] Furthermore, since the phases of the first fixed-wavelength laser and the second fixed-wavelength laser can remain constant or change by π in the first phase modulator, when the phase changes by π, the first fixed-wavelength laser becomes the maximum value of the frequency response curve, and the second fixed-wavelength laser becomes the minimum value of the frequency response curve. By controlling the radio frequency signal, the laser frequency included in the output first carrier signal can be made to jump back and forth between f1 and f2.

[0085] The operation of the second modulation submodule in generating the second carrier signal based on the reverse control radio frequency signal is the same as the operation of the first modulation submodule in generating the first carrier signal based on the control radio frequency signal, and will not be described again here.

[0086] Figure 5The illustration schematically shows a laser frequency jump in the first and second carrier signals of an optical frequency hopping encrypted communication system based on a time-delay interferometer according to an embodiment of the present disclosure.

[0087] like Figure 5 As shown, the control radio frequency signals generated by the radio frequency signal generation module are sequentially "01001011101001", and the reverse control radio frequency signals are sequentially "10110100010110". The first fixed-wavelength laser generated by the laser generation module 311 is at the minimum value of the frequency response curve, and the second fixed-wavelength laser generated is at the maximum value of the frequency response curve. When the binary value of the first bit of the control radio frequency signal is "0" and the corresponding binary value of the first bit of the reverse control radio frequency signal is "1", the phase of the first and second fixed-wavelength lasers does not change in the first modulator, while the phase of the first and second fixed-wavelength lasers changes by π in the second modulator. In the first time-delay interferometer, the first fixed-wavelength laser undergoes "destructive interference," the second fixed-wavelength laser undergoes "constructive interference," and finally, only the laser with frequency f2 is retained at the first position of the control radio frequency signal corresponding to the first carrier signal. In the second time-delay interferometer, the first fixed-wavelength laser undergoes "constructive interference," the second fixed-wavelength laser undergoes "destructive interference," and finally, only the laser with frequency f1 is retained at the first position of the reverse control radio frequency signal corresponding to the second carrier signal.

[0088] According to embodiments of this disclosure, the upper and lower arms of the time-delay interferometer have a stable time delay difference, thereby maintaining a good extinction ratio so that destructive bands during interference do not remain in the carrier wave. In practical applications, a larger extinction ratio can be achieved by controlling the optical power of the upper and lower branches to be equal. Therefore, fiber optic delay lines or Mach-Zehnder interferometers can be used as time-delay interferometers.

[0089] The operation of controlling the generation of the first carrier signal and the second carrier signal by the binary value of the nth bit of the control radio frequency signal and the corresponding reverse control radio frequency signal is the same as the operation described above, and will not be repeated here. Finally, a first carrier signal and a second carrier signal are generated, which include a discontinuous laser with alternating first and second fixed wavelengths, and at the same time, the wavelengths of the first carrier signal and the second carrier signal are different.

[0090] According to embodiments of this disclosure, the signal modulation and transmission module 313 includes:

[0091] First Mach-Zehnder modulator, second Mach-Zehnder modulator and coupler;

[0092] The first Mach-Zehnder modulator is used to modulate the first carrier signal with the first signal to be transmitted to generate the first transmit signal.

[0093] The second Mach-Zehnder modulator is used to modulate the second carrier signal with the second signal to be transmitted to generate the second transmit signal.

[0094] The coupler couples the first transmitted signal and the second transmitted signal and outputs the coupled first transmitted signal and the second transmitted signal.

[0095] More specifically, the first Mach-Zehnder modulator modulates the first signal to be transmitted onto the first carrier signal, and the second Mach-Zehnder modulator modulates the second signal to be transmitted onto the second carrier signal. Since the wavelengths of the first carrier signal and the second carrier signal are different at the same time, there is no overlap between the first signal to be transmitted and the second signal to be transmitted, resulting in high transmission stability.

[0096] According to an embodiment of this disclosure, the demodulation signal generation module 321 includes a wavelength demultiplexer.

[0097] A wavelength demultiplexer (deMUX) is used to receive a coupled first and second transmitted signal from a transmitting station, and to generate a first demodulated signal and a second demodulated signal based on the coupled first and second transmitted signals.

[0098] Figure 6 The illustration schematically shows a data hopping diagram in a receiver of an optical frequency hopping encrypted communication system based on a time-delay interferometer according to an embodiment of the present disclosure.

[0099] like Figure 6 As shown, the wavelength demultiplexer divides the coupled first and second transmitted signals according to different wavelengths, restoring them to obtain a first demodulated signal and a second demodulated signal. The first demodulated signal includes a first fixed-wavelength continuous-wave laser, and the second demodulated signal includes a second fixed-wavelength continuous-wave laser. Both the first and second fixed-wavelength continuous-wave lasers contain alternating second and second transmitted signals, and at the same time, the transmitted signals appearing in the first and second fixed-wavelength continuous-wave lasers are different.

[0100] According to embodiments of this disclosure, demodulation module 322 includes: a pseudo-random sequence generator and a 2×2 optical switch.

[0101] A pseudo-random sequence generator is used to generate a control sequence; a 2×2 optical switch is used to generate a first decryption signal and a second decryption signal based on the control sequence, using the first demodulated signal and the second demodulated signal.

[0102] According to an embodiment of this disclosure, a pseudo-random sequence generator is used to generate a control sequence based on a preset seed source. Since the preset seed source of the receiver-side pseudo-random sequence generator is the same as that of the transmitter-side pseudo-random sequence generator, the control sequence generated by the receiver-side pseudo-random sequence generator is the same as that generated by the transmitter-side pseudo-random sequence generator.

[0103] According to embodiments of this disclosure, a 2×2 optical switch may include an input port 1, an input port 2, an output port 3, and an output port 4. Input port 1 is configured to receive a first demodulated signal, and input port 2 is configured to receive a second demodulated signal. The 2×2 optical switch can alternately output the first and second demodulated signals from output port 3 and output port 4 according to a control sequence. When the pseudo-random binary array in the control sequence is "0", the first demodulated signal is output from output port 3, and the second demodulated signal is output from output port 4; when the pseudo-random binary array in the control sequence is "1", the first demodulated signal is output from output port 4, and the second demodulated signal is output from output port 3.

[0104] According to embodiments of this disclosure, by alternating outputs of a 2×2 optical switch, a first signal to be transmitted and a second signal to be transmitted, comprising the first signal to be demodulated and the second signal to be demodulated, are separated to generate a first decryption signal and a second decryption signal. Each of the first and second decryption signals comprises discontinuous laser light with alternating first and second fixed wavelengths. The discontinuous laser light of the first decryption signal contains only the first signal to be transmitted, and the discontinuous laser light of the second decryption signal contains only the second signal to be transmitted.

[0105] According to an embodiment of this disclosure, the signal detection module 323 may include: a first detector and a second detector. The first detector is used to receive discontinuous laser light with alternating first and second fixed wavelengths carrying only a first signal to be transmitted, and obtain the first signal to be transmitted through photoelectric conversion. The second detector is used to receive discontinuous laser light with alternating first and second fixed wavelengths carrying only a second signal to be transmitted, and obtain the second signal to be transmitted through photoelectric conversion.

[0106] According to embodiments of this disclosure, data to be transmitted can be obtained based on a first signal to be transmitted and a second signal to be transmitted, according to a preset data set.

[0107] According to embodiments of this disclosure, the transmitter and receiver of an optical frequency hopping encrypted communication system based on a time-delay interferometer can be connected via optical fiber.

[0108] According to embodiments of this disclosure, an optical fiber amplifier can be added before the receiver of an optical frequency hopping encrypted communication system based on a time-delay interferometer to amplify the coupled first and second transmitted signals, thereby eliminating the loss generated by the coupled first and second transmitted signals during optical fiber transmission.

[0109] According to embodiments of this disclosure, in an optical frequency hopping encrypted communication system based on a time-delay interferometer, the transmitter can modulate preset data to be transmitted onto lasers of different wavelengths under the control of a control sequence, thereby enabling the preset data to be transmitted to randomly switch between channels corresponding to different wavelengths, thus preventing information leakage and illegal eavesdropping.

[0110] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A transmitter, comprising: A laser generation module is used to generate a carrier signal, wherein the carrier signal includes a continuous wave laser with a first fixed wavelength and a second fixed wavelength; A phase modulation and delay interference module is used to process the carrier signal according to a control sequence, generating a first carrier signal and a second carrier signal respectively. The control sequence is a pseudo-random binary array generated based on a preset seed source. Each of the first and second carrier signals includes discontinuous laser light with alternating first and second fixed wavelengths, and at any given moment, the wavelengths of the first and second carrier signals are different. The signal modulation and transmission module is used to modulate the first carrier signal and the first signal to be transmitted to generate a first transmission signal; it is also used to modulate the second carrier signal and the second signal to be transmitted to generate a second transmission signal, and couple the first transmission signal and the second transmission signal for transmission, wherein the first signal to be transmitted and the second signal to be transmitted are two complementary signals formed according to preset data to be transmitted; The phase modulation and delay interference module includes: a radio frequency signal generation module, a first modulation submodule, and a second modulation submodule; wherein, The radio frequency signal generation module is used to generate control radio frequency signals and reverse control radio frequency signals according to the control sequence; The first modulation submodule is used to generate a first carrier signal based on the control radio frequency signal and the carrier signal; and The second modulation submodule is used to generate a second carrier signal based on the reverse control radio frequency signal and the carrier signal; The first modulation submodule includes a first modulator and a first delay interferometer; The first modulator is used to perform phase modulation on the carrier signal according to the control radio frequency signal to generate a first modulated carrier signal, wherein the phase of the first modulated carrier signal remains unchanged or changes by π according to the control radio frequency signal; The first delay interferometer is used to delay and interfere with the first modulated carrier signal to generate a first carrier signal; The second modulation submodule includes a second modulator and a second delay interferometer; The second modulator is used to perform phase modulation on the carrier signal according to the reverse control radio frequency signal to generate a second modulated carrier signal, wherein the phase of the second modulated carrier signal remains constant or changes by π according to the reverse control radio frequency signal; and The second delay interferometer is used to delay and interfere with the second modulated carrier signal to generate a second carrier signal.

2. The transmitter as claimed in claim 1, wherein, The radio frequency signal generation module includes a pseudo-random sequence generator, an inverter, and a differential encoder; The pseudo-random sequence generator is used to generate a control sequence based on a preset seed source and divide the control sequence into a first control sequence and a second control sequence. The inverter is used to receive the first control sequence and generate the reverse control sequence; The differential encoder is used to generate a control radio frequency signal based on the second control sequence, and also to generate a reverse control radio frequency signal based on the reverse control sequence.

3. The transmitter as claimed in claim 1, wherein, The laser generation module includes: a laser generation submodule and a first coupler group; The laser generation submodule is used to generate a first fixed wavelength laser and a second fixed wavelength laser. The first coupler group is used to receive the first fixed-wavelength laser and the second fixed-wavelength laser and generate a carrier signal.

4. The transmitter as claimed in claim 1, wherein, The signal modulation and transmission module includes: First Mach-Zehnder modulator, second Mach-Zehnder modulator and coupler; The first Mach-Zehnder modulator is used to modulate the first carrier signal with the first signal to be transmitted to generate a first transmission signal; The second Mach-Zehnder modulator is used to modulate the second carrier signal with the second signal to be transmitted to generate a second transmission signal; and The coupler couples the first transmitted signal and the second transmitted signal and outputs the coupled first transmitted signal and the second transmitted signal.

5. A receiver, comprising: The demodulated signal generation module is used to generate a first demodulated signal and a second demodulated signal from the first transmitted signal and the second transmitted signal coupled to the transmitter according to any one of claims 1-4. The demodulation module is configured to process the first demodulated signal and the second demodulated signal according to the control sequence to generate a first decrypted signal and a second decrypted signal. The control sequence is a pseudo-random binary array generated based on a preset seed source. The first and second decrypted signals each include discontinuous laser light with alternating first and second fixed wavelengths, and at the same time, the wavelengths of the first and second decrypted signals are different. The signal detection module is used to obtain a first signal to be transmitted carried on the first decryption signal based on the first decryption signal, and is also used to obtain a second signal to be transmitted carried on the second decryption signal based on the second decryption signal, wherein the first signal to be transmitted and the second signal to be transmitted are two complementary signals formed based on preset data to be transmitted.

6. The receiver as claimed in claim 5, wherein, The demodulated signal generation module includes: a wavelength demultiplexer; The wavelength demultiplexer is used to receive a coupled first transmit signal and a second transmit signal emitted by the transmitting station, and to generate a first demodulated signal and a second demodulated signal based on the coupled first transmit signal and second transmit signal.

7. The receiver as claimed in claim 5, wherein, The demodulation module includes: a pseudo-random sequence generator and a 2×2 optical switch; The pseudo-random sequence generator is used to generate the control sequence; The 2×2 optical switch is used to generate the first decryption signal and the second decryption signal based on the first demodulated signal and the second demodulated signal according to the control sequence.

8. An optical frequency hopping encrypted communication system based on a time-delay interferometer, comprising: The transmitter as described in any one of claims 1-4 is configured to process a carrier signal according to a control sequence, generate a first carrier signal and a second carrier signal respectively, and further configured to modulate a first signal to be transmitted with the first carrier signal to generate a first transmit signal, modulate a second signal to be transmitted with the second carrier signal to generate a second transmit signal, and couple the first transmit signal and the second transmit signal for output, wherein the control sequence is a pseudo-random binary array generated based on a preset seed source, and the first signal to be transmitted and the second signal to be transmitted are two complementary signals formed according to preset data to be transmitted; and The receiver as described in any one of claims 5-7 is configured to generate two identical demodulated signals based on the coupled first and second transmitted signals, process the demodulated signals according to the same control sequence as the transmitter, generate a first decrypted signal and a second decrypted signal respectively, generate a first transmit signal based on the first decrypted signal, and generate a second transmit signal based on the second decrypted signal.

9. The optical frequency hopping encrypted communication system as described in claim 8, further comprising: The receiver transmits the coupled first and second transmission signals to the transmitter via an optical fiber. An optical fiber amplifier is provided in front of the receiving port of the transmitter. The optical fiber amplifier is used to amplify the coupled first and second transmitted signals.

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