A broadband chaotic signal generating device and method based on delayed self-heterodyne

Abstract

The present invention discloses a broadband chaotic signal generating device and method based on delayed self-heterodyne, which relates to the technical field of microwave photonics, and includes a master laser, an intensity modulator, a polarization controller, a circulator, a slave laser, a first optical fiber coupler, an adjustable optical fiber delay line, a second optical fiber coupler, a first photodetector, a second photodetector, and a differential amplifier. A periodically changing driving electrical signal is used to drive the intensity modulator to modulate the master laser to change the intensity of the output optical carrier signal, and the generated optical signal is injected into the slave laser, so that the slave laser enters a chaotic state and outputs two chaotic signals. One of the branch signals is delayed by an adjustable optical fiber delay line, so that self-heterodyne detection is performed in the first and second photodetectors to output chaotic signals. The present invention realizes optical heterodyne of two different chaotic signals, achieves the dominant position of eliminating relaxation oscillation, and has the advantages of simple structure, flexible operation, and low cost.

Description

Technical Field

[0001] The invention relates to the technical field of microwave photonics, in particular to a device and method for generating broadband chaotic signals based on delayed self-heterodyne. Background Art

[0002] Since chaotic signals were used to generate random bits, the application of laser chaos in fast physical random bit generation has received widespread attention. The use of multi-bit extraction and supplemented by derivatives or XOR operations can further improve the speed of random number generation. However, the single-bit generation rate is a basic rate determined by the chaos entropy rate, which is related to the bandwidth of the spectrum. At the same time, laser chaos is also used in fields such as confidential communications, but the data encryption speed is inseparable from the effective bandwidth of the signal. With the in-depth study of semiconductor lasers with light injection, it is found that light-injected semiconductor lasers have excellent nonlinear dynamic characteristics, including chaotic dynamic behavior. Therefore, light-injected semiconductor lasers have received widespread attention in the fields of encrypted communications, physical random number generation, laser radar, time domain reflectometer, etc. Unfortunately, the chaotic intensity oscillation of semiconductor lasers is usually dominated by the relaxation oscillation of the laser. In the frequency domain, the power spectrum distribution has an obvious peak at the relaxation oscillation frequency, resulting in the effective bandwidth usually being limited to several GHz. Therefore, the speed of encrypted data, the generation rate of random numbers, and the spatial resolution of laser radar and reflectometer are all limited.

[0003] In order to solve the problem that the effective bandwidth of the power spectrum of light-injected semiconductor lasers is limited, many methods have been proposed to improve the bandwidth of chaotic lasers. For example, the effective bandwidth of light-injected semiconductor lasers can be expanded by injecting a chaotic laser as a master laser into a static laser or injecting a static laser into a chaotic laser. Compared with the single-wavelength injection of light-injected semiconductor lasers, dual-wavelength light injection through two external lasers can further expand the bandwidth of chaotic signals. However, since their physical processes occur in the laser cavity, the above methods cannot eliminate the dominance of laser relaxation oscillations. Therefore, the energy of the signal is concentrated near the relaxation oscillation frequency, the energy is very low in the low-frequency band, and the power spectrum is still uneven.

[0004] Therefore, in order to solve the problem of uneven energy distribution of the output signal of a light-injected semiconductor laser caused by the influence of laser relaxation oscillation, a chaotic signal generation method is urgently needed that can eliminate the dominant effect of laser relaxation oscillation and increase the signal bandwidth. Summary of the invention

[0005] In view of the bandwidth limitation problem existing in the existing chaotic signal generation method based on light injection semiconductor laser, the present invention is proposed.

[0006] Therefore, the problem to be solved by the present invention is how to eliminate the dominant effect of laser relaxation oscillation and improve the chaotic signal generation capability of the signal bandwidth.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0008] In the first aspect, an embodiment of the present invention provides a broadband chaotic signal generating device based on delayed self-heterodyne, which includes: an optical injection module, which changes the optical signal intensity of the main laser through an intensity modulator, and is used to inject optical signals of different intensities into the slave laser, so that the slave laser outputs different chaotic signals; a delay module, which divides the chaotic signal into a first branch signal and a second branch signal through a first optical fiber coupler; an adjustable optical fiber delay line is set in the second branch, which is used to delay the chaotic signal in the second branch and match the transformation period of the modulated signal on the intensity modulator; the first branch signal and the second branch signal are coupled through a second optical fiber coupler; a balanced photoelectric detection module, which uses two mutually matched and highly consistent photoelectric detectors and a differential amplifier to form a balanced photoelectric detector, which is used to perform heterodyne detection on the signal and differentially subtract the signal after photoelectric conversion to obtain a high-quality chaotic signal that eliminates common-mode noise.

[0009] As a preferred solution of the broadband chaotic signal generating device based on delayed self-heterodyne described in the present invention, wherein: the light injection module includes a master laser, an intensity modulator, a polarization controller, an optical circulator, and a slave laser; the master laser is a narrow linewidth and high tuning precision laser, used to generate a continuous optical carrier signal as an injected light signal; the intensity modulator is a Mach-Zehnder modulator, used to modulate the injected light signal generated by the master laser by driving an electrical signal; the polarization controller is used to match the polarization direction of the incident light signal and the light signal output from the slave laser to obtain the maximum injection efficiency; the optical circulator is used to realize unidirectional transmission of the light signal along a predetermined path; the slave laser is a distributed feedback semiconductor laser, used to receive the injected light signal and periodically output different chaotic signals.

[0010] As a preferred solution of the broadband chaotic signal generating device based on delayed self-heterodyne described in the present invention, wherein: the delay module includes a first optical fiber coupler, an adjustable optical fiber delay line and a second optical fiber coupler; the first optical fiber coupler is used to divide the generated chaotic signal into a first branch chaotic signal and a second branch chaotic signal; the adjustable optical fiber delay line is used to delay the second branch chaotic signal, and the delay time is equal to the change period of the modulation signal, so that the first branch and the second branch output different chaotic signals at the same time; the second optical fiber coupler is used to couple the output signals of the first branch and the second branch to obtain a coupled chaotic signal, and the coupled chaotic signal is evenly distributed to the first branch and the second branch to obtain the first branch coupled chaotic signal and the second branch coupled chaotic signal.

[0011] As a preferred solution of the broadband chaotic signal generating device based on delayed self-heterodyne described in the present invention, wherein: the balanced photoelectric detection module includes a first photodetector, a second photodetector and a differential amplifier; the first photodetector is used to perform heterodyne detection on the first branch coupled chaotic signal and convert it into a microwave signal; the second photodetector is used to perform heterodyne detection on the second branch coupled chaotic signal and convert it into a microwave signal; the differential amplifier is used to differentially amplify the microwave signal output by the photodetector, eliminate common mode noise, and couple it into one signal for output.

[0012] As a preferred solution of the broadband chaotic signal generating device based on delayed self-heterodyne of the present invention, the modulation signal is a driving electrical signal with periodic amplitude variation, which is used to control the modulator to periodically change the parameters of the injected optical signal.

[0013] In the second aspect, an embodiment of the present invention provides a method for generating a broadband chaotic signal based on delayed self-heterodyne, which includes: generating a continuous optical carrier signal based on a master laser and outputting a chaotic signal through a slave laser; dividing the chaotic signal into a first branch signal and a second branch signal through a first optical fiber coupler, and coupling the first branch signal and the second branch signal through the second optical fiber coupler; heterodyne detection and differential amplification of the coupled signal through a photodetector and a differential amplifier to obtain a high-quality chaotic signal.

[0014] As a preferred solution of the broadband chaotic signal generation method based on delayed self-heterodyne described in the present invention, the output of the chaotic signal includes: generating a continuous optical carrier signal through a main laser, and using a driving electrical signal with a periodic amplitude change to drive the intensity modulator to modulate the continuous optical carrier signal to change the intensity of the optical carrier signal; injecting the modulated continuous optical carrier signal output by the modulator into the slave laser through a polarization controller and a circulator, so that the slave laser excites dynamic behavior to output a chaotic signal, and the generated chaotic signal switches periodically with the driving electrical signal.

[0015] As a preferred solution of the broadband chaotic signal generation method based on delayed self-heterodyne described in the present invention, the coupling of the chaotic signal includes: dividing the chaotic signal into a first chaotic signal and a second chaotic signal through a first optical fiber coupler, wherein the first chaotic signal enters a first branch, and the second chaotic signal enters a second branch, and an adjustable optical fiber delay line is introduced into the second branch to delay the second chaotic signal; coupling the first branch signal with the delayed second branch signal in a second optical fiber coupler to obtain a coupled chaotic signal, and equally distributing the coupled signal to the first branch coupled signal and the second branch coupled signal.

[0016] As a preferred solution of the broadband chaotic signal generation method based on delayed self-heterodyne described in the present invention, wherein: the heterodyne detection is to use the first photodetector and the second photodetector to act on the first branch coupling signal and the second branch coupling signal respectively to perform heterodyne detection, realize the delayed self-heterodyne of the chaotic signal, and output the microwave signal after photoelectric conversion; the differential amplification is to differentially amplify the signals of the first branch and the second branch through a differential amplifier, output a broadband chaotic signal that eliminates common mode noise, and output a high-quality chaotic signal.

[0017] As a preferred solution of the broadband chaotic signal generation method based on delayed self-heterodyne described in the present invention, wherein: the variation period of the driving electrical signal must be fixed; and the delay time of the adjustable optical fiber delay line is equal to the variation period of the driving electrical signal.

[0018] The beneficial effects of the present invention are that the delayed self-heterodyne structure of the present invention can use a group of light injection systems to realize the heterodyne of two different chaotic signals, saving costs and being easier to miniaturize and integrate; the use of the light injection structure can avoid the influence of the time delay characteristics and improve the safety and anti-interference ability of the system; the use of the optical heterodyne method can increase the bandwidth of the chaotic signal, eliminate the influence of relaxation oscillations, and improve the distance resolution of the chaotic laser radar detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

[0020] Figure 1 Schematic diagram of a broadband chaotic signal generating device based on delayed self-heterodyne;

[0021] Figure 2 A timing diagram of chaotic signals generated based on the present invention and outputted in the first and second branches and the differential amplifier respectively;

[0022] Figure 3 The spectrum diagram and bandwidth calculation results of chaotic signals generated by the traditional light injection system and the system proposed by the present invention. DETAILED DESCRIPTION

[0023] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0024] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0025] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0026] Embodiment 1, as Figure 1 The figure shows a schematic diagram of a broadband chaotic signal generating device based on delayed self-heterodyne of the present invention, and the figure marks are supplemented with the following explanations: 1. master laser; 2. intensity modulator; 3. periodically varying modulation signal; 4. polarization controller; 5. slave laser; 6. optical circulator; 7. first optical fiber coupler; 8. adjustable optical fiber delay line; 9. second optical fiber coupler; 10. first photodetector; 11. second photodetector; 12. differential amplifier.

[0027] Reference Figure 1 , which is the first embodiment of the present invention, provides a broadband chaotic signal generating device based on delayed self-heterodyne, comprising:

[0028] The light injection module changes the intensity of the optical signal of the master laser 1 through an intensity modulator 2, thereby injecting optical signals of different intensities into the slave laser 5, so that the slave laser 5 outputs different signals;

[0029] A delay module is used to divide the chaotic signal into a first branch and a second branch through a first optical fiber coupler; an adjustable optical fiber delay line is set in the second branch to delay the chaotic signal in the second branch to match the transformation period of the modulated signal on the intensity modulator; the first branch signal and the second branch signal are coupled through a second optical fiber coupler; and the module includes: a first optical fiber coupler 7; an adjustable optical fiber delay line 8; and a second optical fiber coupler 9.

[0030] The balanced photoelectric detection module uses two mutually matched and highly consistent photoelectric detectors and a differential amplifier to form a balanced photoelectric detector, performs heterodyne detection on the signal and performs differential subtraction on the signal after photoelectric conversion to obtain a high-quality chaotic signal that eliminates common-mode noise; it includes: a first photodetector 10; a second photodetector 11; and a differential amplifier 12.

[0031] When working, the optical carrier signal output by the master laser is modulated in the intensity modulator as an injected optical signal, and the intensity modulator is driven by a driving electrical signal with a periodically changing amplitude. The periodically changing driving signal causes the intensity of the modulated injected optical signal to change periodically, thus realizing the periodic switching of the injected optical signal. The modulated injected optical signal is injected into the slave laser after passing through the circulator, causing the slave laser to enter a chaotic state and output a chaotic signal.

[0032] Preferably, the time delay characteristics of the signal are effectively suppressed by the optical injection system, thereby improving the randomness of the chaotic signal, facilitating random bit generation, and improving the security of chaotic communication.

[0033] Since the intensity of the injected optical signal is switched periodically, the switching of the chaotic signal output from the laser is realized through appropriate settings. The periodically switched chaotic signal is divided into a first branch chaotic signal and a second branch chaotic signal after passing through the first optical fiber coupler. An adjustable optical fiber delay line is introduced into the second branch to delay the chaotic signal. The delay time of the adjustable optical fiber delay line is adjusted to be consistent with the change period of the driving electrical signal. After the delay, the second branch chaotic signal is coupled with the first branch chaotic signal in the second optical fiber coupler to realize the coupling of two different chaotic signals.

[0034] On the basis of not changing the light injection structure, the injection of two optical signals is realized by switching the light injection signal, and the optical delay is introduced to realize the coupling of the two signals, realizing the effect of delayed self-heterodyne, using fewer lasers, with a simple structure, cost saving and flexible operation, while also improving the bandwidth of the chaotic signal of the light injection system.

[0035] Then, the first branch coupling signal and the second branch coupling signal are divided into the first branch coupling signal and the second branch coupling signal in a ratio of 50:50. The first branch coupling signal is subjected to heterodyne detection in the first photodetector and then output to the differential amplifier, while the second branch coupling signal is also subjected to heterodyne detection in the second photodetector. The second photodetector is completely consistent with the first photodetector.

[0036] Finally, the two signals are input into the differential amplifier to eliminate the common mode noise through differential operation, and the high-quality heterodyne signal after delayed self-heterodyne is output to realize the output of broadband chaotic signal.

[0037] And by processing chaotic signals with a delayed self-heterodyne structure, the dominant effect of relaxation oscillation is effectively suppressed, the energy of the signal in the low-frequency band is increased, the flatness of the signal power spectrum is increased, the bandwidth of the signal is increased, and the random number generation rate, data encryption speed and radar resolution can be improved.

[0038] Furthermore, the variation period of the driving electrical signal of the intensity modulator should be fixed and can be set using an arbitrary waveform generator so as to match the delay time of the adjustable optical fiber delay line; the electro-optic intensity modulator can be optionally a Mach-Zehnder modulator; the master laser is preferably a narrow linewidth high tuning precision laser; the slave laser is preferably a distributed feedback semiconductor laser; the first photodetector and the second photodetector are preferably photodetectors with high photoelectric conversion efficiency; the first photodetector, the second photodetector and the differential amplifier can be replaced by a balanced photodetector to achieve the same effect.

[0039] Example 2, reference Figure 2 and Figure 3 Based on the first embodiment, this embodiment further provides a method for generating a broadband chaotic signal based on delayed self-heterodyne, comprising:

[0040] S1: The main laser generates a continuous optical carrier signal, and uses a driving electrical signal with a periodically changing amplitude to drive the intensity modulator to modulate the continuous optical carrier signal to change the intensity of the optical carrier signal;

[0041] S2: injecting the modulated continuous optical carrier signal output by the modulator into the slave laser through the polarization controller and the circulator, so that the slave laser excites dynamic behavior to output a chaotic signal, and the generated chaotic signal also switches periodically with the driving electrical signal;

[0042] S3: The first optical fiber coupler is used to divide the chaotic signal into a first chaotic signal and a second chaotic signal, wherein the first chaotic signal enters the first branch and the second chaotic signal enters the second branch, and an adjustable optical fiber delay line is introduced into the second branch to delay the second chaotic signal;

[0043] S4: the first branch signal and the delayed second branch signal are coupled in a second optical fiber coupler to obtain a coupled chaotic signal, which is further divided into the first branch and the second branch coupled signal in a ratio of 50:50;

[0044] S5: using the first photodetector to perform heterodyne detection on the first branch coupled signal, thereby realizing delayed self-heterodyne of the chaotic signal, and outputting a microwave signal after photoelectric conversion;

[0045] S6: similarly using the second photodetector to perform heterodyne detection on the second branch coupling signal, and outputting a microwave signal after photoelectric conversion;

[0046] S7: The differential amplifier differentially amplifies the signals of the first branch and the second branch, and outputs a broadband chaotic signal that eliminates common mode noise.

[0047] When working, the optical carrier signal output by the master laser is modulated in the intensity modulator as an injected optical signal, and the intensity modulator is driven by a driving electrical signal with a periodic change in amplitude, and the period is set to 50 ns. The periodic change of the driving signal causes the intensity of the modulated injected optical signal to change periodically, thereby realizing the periodic switching of the injected optical signal. The modulated injected optical signal is injected into the slave laser after passing through the circulator, causing the slave laser to enter a chaotic state and output a chaotic signal. Since the intensity of the injected optical signal is switched periodically, the switching of the chaotic signal output by the slave laser is realized through appropriate settings.

[0048] like Figure 2 As shown, set the detuning frequency , injection intensity The periodic switching between 0.04 and 0.051 generates a periodic switching chaotic signal. The periodic switching chaotic signal is divided into a first branch chaotic signal and a second branch chaotic signal after passing through the first optical fiber coupler. An adjustable optical fiber delay line is introduced into the second branch to delay the chaotic signal. The delay time of the adjustable optical fiber delay line is adjusted to be consistent with the change period of the driving electrical signal, such as Figure 2As shown in , the delay time is set to 50 ns. After the delay, the second branch chaotic signal is coupled with the first branch chaotic signal in the second fiber coupler to achieve the coupling of two different chaotic signals. Then, it is divided into the first branch coupled signal and the second branch coupled signal in a ratio of 50:50. After the first branch coupled signal is heterodyne detected in the first photodetector, it is output to the differential amplifier. The time domain waveform of the delayed heterodyne signal is shown in Figure 2 The second branch coupling signal is also heterodyne detected in the second photodetector, and the second photodetector is completely consistent with the first photodetector.

[0049] Finally, the two signals are input into the differential amplifier to eliminate the common mode noise through differential operation, and the high-quality heterodyne signal after delay self-heterodyne is output to achieve the output of broadband chaotic signal. The bandwidth improvement result of chaotic signal is as follows: Figure 3 As shown, this embodiment uses 80% of the spectrum energy as the effective bandwidth to measure the bandwidth performance. The initial chaotic signal generated by the traditional light injection structure, the parameters are set as the detuning frequency , injection intensity = 0.04 and detuned frequency , injection intensity =0.051, it can be seen from the power spectrum that its main frequency components are concentrated near the relaxation oscillation frequency.

[0050] According to calculation, the effective bandwidth within the range of 50 GHz is only 20.95 GHz and 21.13 GHz, indicating that the traditional light injection system is greatly affected by relaxation oscillation. In comparison, the delayed self-heterodyne chaotic signal generated by the scheme proposed by the present invention has a significantly broadened and very flat power spectrum, which improves the energy distribution of the chaotic signal in the low frequency band. The effective bandwidth is increased to 32.88 GHz after calculation, which suppresses the dominant role of relaxation oscillation in the traditional light injection structure, thereby expanding the effective bandwidth of the signal.

[0051] In summary, the delayed self-heterodyne structure proposed in the present invention can use a set of light injection systems to realize the heterodyne of two different chaotic signals, which saves costs and is easier to miniaturize and integrate; secondly, the use of the light injection structure can avoid the influence of the time delay characteristics and improve the security and anti-interference ability of the system; the use of the optical heterodyne method can increase the bandwidth of the chaotic signal, eliminate the influence of relaxation oscillations, and improve the distance resolution of the chaotic lidar detection.

[0052] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A broadband chaotic signal generating device based on delayed self-heterodyne, characterized in that: include, An optical injection module is used to inject optical signals of different intensities into the slave laser so that the slave laser outputs different signals; A delay module, comprising a first optical fiber coupler, an adjustable optical fiber delay line and a second optical fiber coupler; The first optical fiber coupler is used to divide the generated chaotic signal into a first branch chaotic signal and a second branch chaotic signal; The adjustable optical fiber delay line is used to delay the chaotic signal of the second branch, and the delay time is equal to the change period of the modulation signal, so that the first branch and the second branch output different chaotic signals at the same time; The second optical fiber coupler is used to couple the output signals of the first branch and the second branch to obtain a coupled chaotic signal, and to evenly distribute the coupled chaotic signal to the first branch and the second branch to obtain a first branch coupled chaotic signal and a second branch coupled chaotic signal; A balanced photodetection module, comprising a first photodetector, a second photodetector and a differential amplifier; The first photoelectric detector is used to perform heterodyne detection on the first branch coupled chaotic signal and convert it into a microwave signal; The second photoelectric detector is used to perform heterodyne detection on the second branch coupled chaotic signal and convert it into a microwave signal; The differential amplifier is used to differentially amplify the microwave signal output by the photodetector, eliminate common mode noise, and couple it into one signal for output.

2. The broadband chaotic signal generating device based on delayed self-heterodyne as claimed in claim 1, characterized in that: The light injection module comprises a master laser, an intensity modulator, a polarization controller, an optical circulator, and a slave laser; The main laser is a narrow line width high tuning precision laser, which is used to generate a continuous optical carrier signal as an injected optical signal; The intensity modulator is a Mach-Zehnder modulator, which is used to modulate the injected optical signal generated by the master laser through a driving electrical signal; The polarization controller is used to match the polarization direction of the incident optical signal and the optical signal output from the laser to obtain the maximum injection efficiency; The optical circulator is used to realize unidirectional transmission of optical signals along a predetermined path; The slave laser is a distributed feedback semiconductor laser, which is used to receive an injected optical signal and periodically output different chaotic signals.

3. The broadband chaotic signal generating device based on delayed self-heterodyne as claimed in claim 2, characterized in that: The modulation signal is a driving electrical signal with a periodically changing amplitude, and is used to control the modulator to periodically change the parameters of the injected optical signal.

4. A method for generating a broadband chaotic signal based on delayed self-heterodyne, based on the broadband chaotic signal generating device based on delayed self-heterodyne according to any one of claims 1 to 3, characterized in that: include, generating a continuous optical carrier signal based on a master laser and outputting a chaotic signal through a slave laser; Dividing the chaotic signal into a first branch signal and a second branch signal through a first optical fiber coupler, and coupling the first branch signal and the second branch signal through the second optical fiber coupler; The coupled signal is heterodyne detected and differentially amplified through a photodetector and a differential amplifier to obtain a high-quality chaotic signal.

5. The method for generating a broadband chaotic signal based on delayed self-heterodyne according to claim 4, characterized in that: The output of the chaotic signal includes: A continuous optical carrier signal is generated by a main laser, and a driving electrical signal with a periodically changing amplitude is used to drive an intensity modulator to modulate the continuous optical carrier signal to change the intensity of the optical carrier signal; The modulated continuous optical carrier signal output by the modulator is injected into the slave laser through the polarization controller and the circulator, so that the slave laser excites dynamic behavior to output a chaotic signal, and the generated chaotic signal switches periodically with the driving electrical signal.

6. The method for generating a broadband chaotic signal based on delayed self-heterodyne according to claim 5, characterized in that: The coupling of the chaotic signal comprises: The chaotic signal is divided into a first chaotic signal and a second chaotic signal through a first optical fiber coupler, wherein the first chaotic signal enters a first branch and the second chaotic signal enters a second branch, and an adjustable optical fiber delay line is introduced into the second branch to delay the second chaotic signal; The first branch signal and the delayed second branch signal are coupled in the second optical fiber coupler to obtain a coupled chaotic signal, which is evenly distributed to the first branch coupled signal and the second branch coupled signal.

7. The method for generating a broadband chaotic signal based on delayed self-heterodyne according to claim 6, characterized in that: The heterodyne detection is to use the first photodetector and the second photodetector to act on the first branch coupled signal and the second branch coupled signal respectively to perform heterodyne detection, realize delayed self-heterodyne of the chaotic signal, and output a microwave signal after photoelectric conversion; The differential amplification is to differentially amplify the signals of the first branch and the second branch through a differential amplifier, output a broadband chaotic signal that eliminates common mode noise, and output a high-quality chaotic signal.

8. The method for generating a broadband chaotic signal based on delayed self-heterodyne according to claim 7, characterized in that: The variation cycle of the driving electrical signal must be fixed; the delay time of the adjustable optical fiber delay line is equal to the variation cycle of the driving electrical signal.

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