Optoelectronic oscillator capable of being used for frequency hopping microwave generation

Abstract

The invention provides a photoelectric oscillator capable of being used for frequency hopping microwave generation. The photoelectric oscillator is mainly composed of a laser, a polarization controller, a Mach-Zehnder modulator, a single-mode optical fiber, a photoelectric detector, an electric amplifier, a frequency mixer, an equivalent dual-band filter and a microwave source. Wherein the equivalent dual-band filter is obtained by connecting two narrow-band filters in parallel and serves as a frequency selection device of the optoelectronic oscillator system; hopping is carried out on the loop signal by utilizing the frequency mixer, so that frequency hopping of the loop signal is realized; compared with a traditional scheme, the system has a simpler system structure, the equivalent dual-band filter and the frequency mixer are utilized to enable a photoelectric oscillator loop to continuously perform frequency hopping and conversion, frequency hopping signal generation with loop time delay as a half cycle is realized, and the system has good application in the aspects of signal generation, pulse detection and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of signal generation and processing, and particularly relates to an optoelectronic oscillator that can be used for generating frequency-hopping microwaves. Background Art

[0002] Frequency-hopping microwave signals are a signal technology that transmits information by rapidly switching frequencies, and are widely used in fields such as communication, radar, and electronic warfare. Its basic principle is to rapidly hop the signal within a preset frequency range to enhance anti-jamming capabilities and confidentiality. In modern wireless communication, frequency-hopping technology is commonly used in military communication systems to avoid enemy interference and eavesdropping by rapidly switching between multiple frequency bands. Frequency-hopping radar systems use frequency-hopping technology to improve anti-jamming capabilities and reduce the risk of detection, especially in complex electromagnetic environments; frequency-hopping signals can enhance target recognition capabilities, helping the system to more accurately distinguish different types of targets and suppress background noise; frequency-hopping technology can also reduce the duration of the detection signal, thereby enhancing stealth performance. In radio spectrum monitoring and electronic intelligence collection, frequency-hopping signals can effectively avoid interference and capture important information.

[0003] Optoelectronic oscillators (OEOs) have the characteristics of generating high-frequency, low-phase-noise microwave signals and are widely used in fields such as signal generation and processing, radar, etc. The output signal of a traditional OEO is a single-frequency signal, which has the characteristic of low phase noise. The generation of frequency-hopping signals depends on an external frequency-hopping control system. For example, a research team at Jilin University designed a frequency-hopping signal generator based on the OEO structure, and used a frequency-hopping unit to process the loop output signal to achieve the generation of high-speed frequency-hopping signals. A research team at the Chinese Academy of Sciences designed a frequency-hopping signal generation system using a dual-bandpass microwave photonic filter and realized the generation of pulse signals on this basis. In addition to the proposal of a discrete-type frequency-hopping OEO structure, integrated OEO technology is also constantly developing. A research team at Beijing University of Posts and Telecommunications designed an integrated OEO chip that can be used to generate widely tunable frequency-hopping microwave signals and has a wide range of applications. However, the above OEO frequency-hopping signal generation systems are all relatively complex. Summary of the Invention

[0004] To solve the above problems, the present invention provides an optoelectronic oscillator that can be used for generating frequency-hopping microwaves, which has the advantage of a simple structure. By using an equivalent dual-band filter and a mixer, the optoelectronic oscillator loop continuously performs frequency hopping and conversion, realizing the generation of frequency-hopping signals with a half-period of the loop delay.

[0005] An optoelectronic oscillator that can be used for generating frequency-hopping microwaves includes a laser, a polarization controller, a Mach-Zehnder modulator, a single-mode optical fiber, a photodetector, a mixer, an equivalent dual-band filter, and a microwave source;

[0006] The polarization controller is used to tune the polarization state of the laser signal output by the laser, so that the polarization state of the laser signal is parallel to the main axis of the Mach-Zehnder modulator;

[0007] The Mach-Zehnder modulator is used to modulate the laser signal parallel to its own main axis under the control of the jump signal output by the equivalent dual-band filter to obtain a modulated optical signal;

[0008] The single-mode fiber is used to transmit the modulated optical signal to the photodetector;

[0009] The photodetector is used to convert the modulated optical signal into a modulated electrical signal;

[0010] The microwave source is used to output an intermediate-frequency signal to the mixer;

[0011] The mixer is used to perform spectral shifting on the modulated electrical signal according to the intermediate-frequency signal to obtain a frequency-shifted electrical signal;

[0012] The equivalent dual-band filter is used to perform dual-band filtering on the frequency-shifted electrical signal to obtain a jump signal whose frequency has jumped relative to the modulated optical signal output by the Mach-Zehnder modulator; wherein, the frequencies of the jump signals obtained by any two adjacent dual-band filterings are different, and the frequencies of the jump signals obtained by two dual-band filterings with an intermediate dual-band filtering are the same.

[0013] Further, when the microwave source outputs an intermediate-frequency signal to the mixer and the equivalent dual-band filter performs an odd number of dual-band filterings on the frequency-shifted electrical signal, the frequency-shifted electrical signal V mixer-1 (t) is:

[0014]

[0015] wherein, s1(t) is the jump signal output when the equivalent dual-band filter performs an odd number of dual-band filterings, V1 is the amplitude of the modulated optical signal obtained by the Mach-Zehnder modulator under the control of the jump signal output during an odd number of dual-band filterings, V2 is the amplitude of the intermediate-frequency signal, is the phase shift of the modulated optical signal obtained by the Mach-Zehnder modulator under the control of the jump signal output during an odd number of dual-band filterings, is the phase shift of the intermediate-frequency signal, ω1 is the phase shift of the modulated optical signal obtained by the Mach-Zehnder modulator under the control of the jump signal output during an odd number of dual-band filterings, and ω2 is the angular frequency of the intermediate-frequency signal;

[0016] When the equivalent dual-band filter performs an even number of dual-band filterings on the frequency-shifted electrical signal, the frequency-shifted electrical signal V mixer-2 (t) is:

[0017]

[0018] Among them, s2(t) is the jump signal output when the equivalent dual-band filter performs even-numbered dual-band filtering, and V0 is the amplitude of the modulated optical signal obtained under the control of the jump signal output by the Mach-Zehnder modulator during even-numbered dual-band filtering. is the phase shift of the modulated optical signal obtained under the control of the jump signal output by the Mach-Zehnder modulator during even-numbered dual-band filtering.

[0019] Further, when the microwave source does not output an intermediate-frequency signal, assuming the laser signal output by the laser The mixer does not perform spectral shifting on the modulated electrical signal, then the equivalent dual-band filter performs dual-band filtering on the modulated electrical signal to obtain a single-frequency sine signal with no frequency jump as

[0020] At this time, the modulated optical signal E output by the Mach-Zehnder modulator MZM1 (t) is as follows:

[0021]

[0022] Among them, E0 is the optical intensity of the laser signal, ω c is the center frequency of the laser signal, s(t) is the single-frequency sine signal output by the equivalent dual-band filter, is the phase shift introduced by the single-frequency sine signal s(t), is the phase shift introduced by the bias voltage provided by the external voltage source of the Mach-Zehnder modulator, V B is the bias voltage provided by the external voltage source of the Mach-Zehnder modulator, V π is the half-wave voltage of the Mach-Zehnder modulator.

[0023] Further, an optoelectronic oscillator that can be used for generating frequency-hopping microwaves further includes an electrical amplifier;

[0024] The electrical amplifier is used to amplify the modulated electrical signal output by the photodetector and then input the amplified modulated electrical signal into the mixer.

[0025] Further, an optoelectronic oscillator that can be used for generating frequency-hopping microwaves further includes a directional coupler;

[0026] The directional coupler is used to directionally couple the jump signal output by the equivalent dual-band filter to the Mach-Zehnder modulator.

[0027] Further, the method for the optoelectronic oscillator to obtain the jump signal is:

[0028] A single-wavelength laser signal is output by a laser, and after passing through a polarization controller, the polarization state of the laser signal is parallel to the main axis of the Mach-Zehnder modulator;

[0029] The bias voltage of the Mach-Zehnder modulator is adjusted to make it work at the quadrature transmission point; at this time, the signal output by the equivalent dual-band filter is a single-frequency sine signal;

[0030] The microwave source is turned on to output an intermediate-frequency signal, so that the mixer continuously performs spectral shifting on the modulated electrical signal received in each cycle according to the intermediate-frequency signal to obtain a frequency-shifted electrical signal; among them, the frequencies of the frequency-shifted electrical signals obtained by any two adjacent spectral shifts are different, and the frequencies of the frequency-shifted electrical signals obtained by two spectral shifts with an intermediate spectral shift are the same;

[0031] The equivalent dual-band filter continuously performs dual-band filtering on the frequency-shifted electrical signal to continuously obtain a hopping signal.

[0032] Advantageous effects:

[0033] The present invention provides an optoelectronic oscillator that can be used for frequency-hopping microwave generation, which mainly consists of a laser, a polarization controller, a Mach-Zehnder modulator, a single-mode optical fiber, a photodetector, an electrical amplifier, a mixer, an equivalent dual-band filter, and a microwave source; among them, the equivalent dual-band filter is obtained by connecting two narrow-band filters in parallel and serves as a frequency selection device for the optoelectronic oscillator system; the mixer is used to perform hopping on the signal in the loop to achieve frequency hopping of the loop signal; compared with the traditional scheme, the present invention has a simpler system structure, and uses the equivalent dual-band filter and the mixer to continuously perform frequency hopping and conversion on the optoelectronic oscillator loop, realizing the generation of a frequency-hopping signal with a half-cycle of the loop delay, and has good applications in signal generation, pulse detection, etc. Description of the drawings

[0034] Figure 1 It is a system block diagram of the optoelectronic oscillator provided by the present invention.

[0035] Figure 2 It is a schematic diagram of the transmission function curve of the equivalent dual-band filter provided by the present invention.

[0036] Figure 3 It is a schematic diagram of single-frequency oscillation of the optoelectronic oscillator provided by the present invention.

[0037] Figure 4 It is a frequency-domain graph of the signal output after the mixer injects an intermediate-frequency signal provided by the present invention.

[0038] Figure 5 It is a time-domain graph of the signal output after the mixer injects an intermediate-frequency signal provided by the present invention.

[0039] Figure 6The time-frequency analysis diagram output after injecting an intermediate frequency signal into the mixer provided by the present invention. Detailed implementation manners

[0040] In order to enable those skilled in the art to better understand the solution of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this application.

[0041] As Figure 1 shown, an optoelectronic oscillator that can be used for generating frequency-hopping microwaves includes a laser, a polarization controller, a Mach-Zehnder modulator, a single-mode optical fiber, a photodetector, an electrical amplifier, a mixer, a directional coupler, an equivalent dual-band filter, and a microwave source;

[0042] The laser is used to generate a single-frequency laser signal;

[0043] The polarization controller is used to tune the polarization state of the laser signal output by the laser so that the polarization state of the laser signal is parallel to the main axis of the Mach-Zehnder modulator; it should be noted that for an electro-optic modulator, the polarization state direction of the laser signal affects the modulation efficiency. When the polarization direction is consistent with the main axis direction of the electro-optic modulator, the electro-optic modulation has the highest efficiency;

[0044] The Mach-Zehnder modulator is used to modulate the laser signal parallel to its own main axis under the control of the hopping signal output by the equivalent dual-band filter to obtain a modulated optical signal;

[0045] The single-mode optical fiber is used to transmit the modulated optical signal to the photodetector; it should be noted that the single-mode optical fiber plays a role in increasing the length of the loop optical cavity and improving the quality factor of the output signal in the optoelectronic oscillator;

[0046] The photodetector is used to convert the modulated optical signal into a modulated electrical signal, realizing the conversion from an optical signal to an electrical signal;

[0047] The electrical amplifier is used to amplify the modulated electrical signal output by the photodetector and then input the amplified modulated electrical signal into the mixer, thereby increasing the loop gain and realizing the output of the optoelectronic oscillator;

[0048] The microwave source is used to output an intermediate frequency signal to the mixer;

[0049] The mixer is used to perform spectral shifting on the modulated electrical signal according to the intermediate frequency signal to obtain a frequency-shifted electrical signal; it should be noted that the mixer has two input ports and one output port. Among them, port 1 is used for injecting the modulated electrical signal after beat frequency by the photodetector, port 2 is used for injecting the intermediate frequency signal of the microwave source, and port 3 is used for outputting the frequency-shifted electrical signal after mixing the signals of port 1 and port 2;

[0050] AsFigure 2 As shown, the equivalent dual-band filter is composed of two parallel narrow-band band-pass filters. As the filtering structure of the loop, it is used to perform dual-band filtering on the frequency-shifted electrical signal to obtain a jump signal whose frequency has jumped relative to the modulated optical signal output by the Mach-Zehnder modulator. Among them, the frequencies of the jump signals obtained by any two adjacent dual-band filterings are different, and the frequencies of the jump signals obtained by two dual-band filterings with one dual-band filtering in between are the same;

[0051] The directional coupler is used to directionally couple the jump signal output by the equivalent dual-band filter to the Mach-Zehnder modulator.

[0052] The principle of obtaining the frequency-hopping microwave signal by the optoelectronic oscillator provided by the present invention is as follows:

[0053] The laser signal output by the laser can be expressed as:

[0054] When the microwave source does not output an intermediate-frequency signal, the mixer does not perform spectral shifting on the modulated electrical signal. Then, the equivalent dual-band filter performs dual-band filtering on the modulated electrical signal to obtain a single-frequency sine signal whose frequency has not jumped as The single-frequency sine signal s(t) enters the dual-drive Mach-Zehnder modulator for intensity modulation. Due to the positive feedback characteristic of the optoelectronic oscillator, at this time, the modulated optical signal E MZM1 (t) is as follows:

[0055]

[0056] Among them, E0 is the optical intensity of the laser signal, ω c is the center frequency of the laser signal, s(t) is the single-frequency sine signal output by the equivalent dual-band filter, is the phase shift introduced by the single-frequency sine signal s(t), is the phase shift introduced by the bias voltage provided by the external voltage source of the Mach-Zehnder modulator, V B is the bias voltage provided by the external voltage source of the Mach-Zehnder modulator, V π is the half-wave voltage of the Mach-Zehnder modulator.

[0057] At this time, the output signal of the Mach-Zehnder modulator is transmitted through a long optical fiber and finally beat in the photodetector. The photodetector signal can be expressed as:

[0058] V PD (t) ∝ s(t)

[0059] It can be seen from this that if the mixer does not inject an intermediate-frequency signal, the microwave signal of the entire optoelectronic oscillator loop is single-frequency.

[0060] Furthermore, when the microwave source outputs an intermediate frequency signal to the mixer and the equivalent dual-band filter performs an odd-numbered dual-band filtering on the frequency-shifted electrical signal, the frequency-shifted electrical signal V mixer-1 (t) is as follows:

[0061]

[0062] where s1(t) is the jump signal output when the equivalent dual-band filter performs an odd-numbered dual-band filtering, V1 is the amplitude of the modulated optical signal obtained under the control of the jump signal output by the Mach-Zehnder modulator during the odd-numbered dual-band filtering, V2 is the amplitude of the intermediate frequency signal, is the phase shift of the modulated optical signal obtained under the control of the jump signal output by the Mach-Zehnder modulator during the odd-numbered dual-band filtering, is the phase shift of the intermediate frequency signal, ω1 is the phase shift of the modulated optical signal obtained under the control of the jump signal output by the Mach-Zehnder modulator during the odd-numbered dual-band filtering, and ω2 is the angular frequency of the intermediate frequency signal;

[0063] It can be seen from this that the mixer performs spectral shifting on the modulated optical signal output by the Mach-Zehnder modulator, and then filters out the unwanted frequencies through the equivalent dual-band filter, and the frequency of the jump signal can be recorded as |ω1 - ω2| / 2π. The jump signal is fed back to the Mach-Zehnder modulator, and electro-optic modulation and single-mode fiber transmission are performed again, and then it reaches the mixer again through the photodetector and the electrical amplifier for another mixing. Assuming that the previous mixing is an odd-numbered mixing, then this time it is equivalent to an even-numbered mixing. Based on this, when the equivalent dual-band filter performs an even-numbered dual-band filtering on the frequency-shifted electrical signal, the frequency-shifted electrical signal V mixer-2 (t) is as follows:

[0064]

[0065] where s2(t) is the jump signal output when the equivalent dual-band filter performs an even-numbered dual-band filtering, and V0 is the amplitude of the modulated optical signal obtained under the control of the jump signal output by the Mach-Zehnder modulator during the even-numbered dual-band filtering, is the phase shift of the modulated optical signal obtained under the control of the jump signal output by the Mach-Zehnder modulator during the even-numbered dual-band filtering.

[0066] That is to say, the frequency-shifted electrical signal obtained by the even-numbered spectrum shift this time is filtered by the equivalent dual-band filter and then a signal with a frequency of ω1 / 2π is obtained again. That is, the frequency of the frequency-shifted electrical signal obtained by the even-numbered spectrum shift this time jumps back to the frequency of the modulated optical signal output by the Mach-Zehnder modulator before the previous odd-numbered spectrum shift. Therefore, in the optoelectronic oscillator system of the present invention, every time the loop signal transmits one circle, that is, a frequency jump occurs, and the frequency of the jump is related to the injection signal and the center frequency of the equivalent dual-band filter.

[0067] Further, the method for the optoelectronic oscillator to obtain the jump signal is as follows:

[0068] Use a laser to output a single-wavelength laser signal. After passing through a polarization controller, the polarization state of the laser signal is parallel to the main axis of the Mach-Zehnder modulator, and the laser signal will obtain the maximum modulation efficiency in the Mach-Zehnder modulator;

[0069] Adjust the bias voltage of the Mach-Zehnder modulator so that it works at the quadrature transmission point; at this time, the signal output by the equivalent dual-band filter is a single-frequency sine signal;

[0070] Set the operating voltages of the photodetector and the electrical amplifier to the normal operating state;

[0071] Turn on the microwave source to make the microwave source output an intermediate-frequency signal. Set the frequency of the intermediate-frequency signal to the frequency difference of the parallel passbands of the equivalent dual-band filter, and set the output power to 10 dBm, so that the mixer continuously performs spectrum shift on the modulated electrical signal received each cycle according to the intermediate-frequency signal to obtain a frequency-shifted electrical signal; among them, the frequencies of the frequency-shifted electrical signals obtained by any two adjacent spectrum shifts are different, and the frequencies of the frequency-shifted electrical signals obtained by two spectrum shifts with one spectrum shift in between are the same;

[0072] The equivalent dual-band filter continuously performs dual-band filtering on the frequency-shifted electrical signal to continuously obtain the jump signal.

[0073] The performance results of the optoelectronic oscillator provided by the present invention are as Figures 3 to 6 shown. The experimental parameters of this test are as follows: the output power of the laser is 14 dBm, the 3 dB bandwidth of the Mach-Zehnder modulator is 40 GHz, the length of the single-mode fiber is 1 km, the 3 dB bandwidth of the photodetector is 33 GHz, the output bandwidth of amplifier 1 is 20 GHz, the gain is 20 dBm, the output bandwidth of amplifier 2 is 18 dB, the gain is 29 dBm, and the output range of the mixer is 2 - 18 GHz.

[0074] Figure 3 Shows the single-frequency oscillation situation of the loop when the microwave source has no output, Figure 4After the injection of the signal, the spectrum of the output signal is in a dual-frequency form. Further, when the mixer injects an intermediate-frequency signal, the time-domain spectrum of the test output signal is as shown in Figure 5 . It can be seen that the output signal jumps with a period of 5 μs, where 5 μs is the time delay of the loop, indicating that the loop signal jumps at the mixer. The time-frequency analysis of the above signal is shown in Figure 6 , which further proves the generation of the frequency-hopping signal from the time-frequency perspective.

[0075] In summary, the present invention proposes an optoelectronic oscillator that can be used for the generation of frequency-hopping microwaves. The optoelectronic oscillator mainly consists of a laser, a polarization controller, a Mach-Zehnder modulator, a single-mode fiber, a photodetector, an electrical amplifier, a mixer, an equivalent dual-band filter, and a microwave source; among them, the equivalent dual-band filter is obtained by connecting two narrow-band filters in parallel and serves as the frequency selection device of the optoelectronic oscillator system; the mixer is used to jump the signal in the loop to achieve frequency hopping of the loop signal; compared with the traditional scheme, the present invention has a simpler system structure and has good applications in aspects such as signal generation and pulse detection.

[0076] Of course, the present invention can also have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can certainly make various corresponding changes and deformations according to the present invention, but these corresponding changes and deformations should all fall within the protection scope of the appended claims of the present invention.

Claims

1. An optoelectronic oscillator that can be used for generating frequency-hopping microwaves, characterized in that, It includes a laser, a polarization controller, a Mach-Zehnder modulator, a single-mode fiber, a photodetector, a mixer, an equivalent dual-band filter, and a microwave source; The polarization controller is used to tune the polarization state of the laser signal output by the laser so that the polarization state of the laser signal is parallel to the main axis of the Mach-Zehnder modulator; The Mach-Zehnder modulator is used to modulate the laser signal parallel to its own main axis under the control of the jump signal output by the equivalent dual-band filter to obtain a modulated optical signal; The single-mode fiber is used to transmit the modulated optical signal to the photodetector; The photodetector is used to convert the modulated optical signal into a modulated electrical signal; The microwave source is used to output an intermediate-frequency signal to the mixer; The mixer is used to perform spectral shifting on the modulated electrical signal according to the intermediate-frequency signal to obtain a frequency-shifted electrical signal; The equivalent dual-band filter is used to perform dual-band filtering on the frequency-shifted electrical signal to obtain a jump signal whose frequency has jumped relative to the modulated optical signal output by the Mach-Zehnder modulator; wherein, the frequencies of the jump signals obtained by any two adjacent dual-band filterings are different, and the frequencies of the jump signals obtained by two dual-band filterings with one dual-band filtering in between are the same.

2. The optoelectronic oscillator for generating frequency-hopping microwaves according to claim 1, characterized in that, When the microwave source outputs an intermediate frequency signal to the mixer When the equivalent dual-band filter performs odd-numbered dual-band filtering on the frequency-shifted electrical signal, the frequency-shifted electrical signal V mixer-1 (t) is as follows: Among them, s1(t) is the jump signal output when the equivalent dual-band filter performs odd-numbered dual-band filtering, V1 is the amplitude of the modulated optical signal obtained under the control of the jump signal output when the Mach-Zehnder modulator performs odd-numbered dual-band filtering, V2 is the amplitude of the intermediate-frequency signal, is the phase shift of the modulated optical signal obtained under the control of the jump signal output when the Mach-Zehnder modulator performs odd-numbered dual-band filtering, is the phase shift of the intermediate-frequency signal, ω1 is the phase shift of the modulated optical signal obtained under the control of the jump signal output when the Mach-Zehnder modulator performs odd-numbered dual-band filtering, and ω2 is the angular frequency of the intermediate-frequency signal; When the equivalent dual-band filter performs even-numbered dual-band filtering on the frequency-shifted electrical signal, the frequency-shifted electrical signal V mixer-2 (t) output by the mixer is as follows: Among them, s2(t) is the jump signal output when the equivalent dual-band filter performs even-numbered dual-band filtering, and V0 is the amplitude of the modulated optical signal obtained under the control of the jump signal output by the Mach-Zehnder modulator during even-numbered dual-band filtering. is the phase shift of the modulated optical signal obtained under the control of the jump signal output by the Mach-Zehnder modulator during even-numbered dual-band filtering.

3. The optoelectronic oscillator as claimed in claim 1 and applicable to the generation of frequency-hopping microwaves, wherein, When the microwave source does not output an intermediate frequency signal, assume the laser signal output by the laser The mixer does not perform spectral shifting on the modulated electrical signal, then the equivalent dual-band filter performs dual-band filtering on the modulated electrical signal, and the single-frequency sine signal with unchanged frequency obtained is At this time, the modulated optical signal E output by the Mach-Zehnder modulator MZM1 (t) is as follows: where E0 is the optical intensity of the laser signal, ω c is the center frequency of the laser signal, s(t) is the single-frequency sine signal output by the equivalent dual-band filter, is the phase shift introduced by the single-frequency sine signal s(t), is the phase shift introduced by the bias voltage provided by the external voltage source of the Mach-Zehnder modulator, V B is the bias voltage provided by the external voltage source of the Mach-Zehnder modulator, V π is the half-wave voltage of the Mach-Zehnder modulator.

4. The optoelectronic oscillator for generating a frequency-hopping microwave according to claim 1, characterized in that, It also includes an electrical amplifier; The electrical amplifier is used to amplify the modulated electrical signal output by the photodetector and then input the amplified modulated electrical signal into the mixer.

5. The optoelectronic oscillator as claimed in claim 1, which can be used for generating frequency-hopping microwaves, is characterized in that, It also includes a directional coupler; The directional coupler is used to directionally couple the jump signal output by the equivalent dual-band filter to the Mach-Zehnder modulator.

6. The optoelectronic oscillator for generating frequency-hopping microwaves according to claim 1, characterized in that The method for the optoelectronic oscillator to obtain the jump signal is as follows: Use the laser to output a single-wavelength laser signal. After passing through the polarization controller, the polarization state of the laser signal is parallel to the main axis of the Mach-Zehnder modulator; Adjust the bias voltage of the Mach-Zehnder modulator so that it works at the quadrature transmission point; at this time, the signal output by the equivalent dual-band filter is a single-frequency sine signal; Turn on the microwave source so that the microwave source outputs an intermediate-frequency signal, so that the mixer continuously performs spectral shifting on the modulated electrical signal received in each cycle according to the intermediate-frequency signal to obtain a frequency-shifted electrical signal; wherein, the frequencies of the frequency-shifted electrical signals obtained by any two adjacent spectral shiftings are different, and the frequencies of the frequency-shifted electrical signals obtained by two spectral shiftings with one spectral shifting in between are the same; The equivalent dual-band filter continuously performs dual-band filtering on the frequency-shifted electrical signal to continuously obtain a jump signal.

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