CN115144841A - Large-bandwidth linear frequency modulation signal generation device and method - Google Patents
Large-bandwidth linear frequency modulation signal generation device and method Download PDFInfo
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- CN115144841A CN115144841A CN202210602644.2A CN202210602644A CN115144841A CN 115144841 A CN115144841 A CN 115144841A CN 202210602644 A CN202210602644 A CN 202210602644A CN 115144841 A CN115144841 A CN 115144841A
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Abstract
The invention discloses a large-bandwidth linear frequency modulation signal generating device and a method, comprising the following steps: a main laser; a frequency shift modulation module; a light intensity modulation module; a slave laser; a photoelectric detection module; the frequency shift modulation module performs frequency shift modulation of different frequency differences on optical carrier signals in a continuous time period, so that the slave laser generates linear frequency modulation optical carrier signals with different frequency sweep ranges, and the linear frequency modulation electrical signals output by the photoelectric detection module are spliced in a time domain to obtain linear frequency modulation electrical signals with increased frequency sweep ranges after splicing; the chirp rate of the chirp electrical signals in different sweep frequency ranges is the same, and the frequency of the chirp electrical signals at the end time of the previous time period and the start time of the next time period is the same in the continuous time period. The device has the characteristics of low cost, simple structure, easy operation, high stability of the generated linear chirp signal and high sweep frequency bandwidth of dozens of GHz.
Description
Technical Field
The invention relates to the technical field of frequency modulation signal generation, in particular to a large-bandwidth linear frequency modulation signal generation device and method.
Background
With the increasing complexity of electromagnetic environment and electronic countermeasure environment, the radar system is rapidly developed towards high frequency band, tunability, large bandwidth, multiple functions and integration. The linear chirp signal is widely applied to modern radar systems because the linear chirp signal has strong pulse compression capability and large time bandwidth product characteristics. The conventional method for generating linear chirp signals in the electrical domain is limited by the rate bottleneck of electronic devices, and cannot meet the increasing requirements of the frequency and bandwidth of signals of modern radar systems. At present, with the rise of the microwave photon interdiscipline, the microwave photon technology has been widely applied to the generation, transmission, processing and the like of modern radar signals. The linear chirp signal generated based on the microwave photon technology has the advantages of high center frequency, large bandwidth, strong anti-electromagnetic interference capability, small transmission loss and the like.
Chirp is generally achieved by modulating the optical signal injected into the slave laser, thereby changing the output frequency of the monocycle oscillation of the slave laser. However, the frequency sweep range of the chirp signal generated by the laser is limited by the single-period dynamic state of the laser; under the condition of the detuning frequency of the same master laser and the same slave laser, if the intensity of an optical signal injected into the slave laser is too large, the dynamic state of the slave laser enters a chaotic state from a single-period oscillation state, so that the slave laser can only output a chirp signal with a limited sweep frequency range. Therefore, when the chirp signal is generated by using the dynamics of the optical injection semiconductor laser, if only the intensity of the injected optical signal is controlled, the frequency sweep range of the generated chirp signal is very limited.
Disclosure of Invention
The invention aims to provide a large-bandwidth linear frequency modulation signal generation device and method, which solve the technical defect that in the prior art, the frequency sweep range of a chirp signal is limited because a slave laser can only be in a single-period oscillation state with single frequency by only carrying out intensity modulation on an optical signal injected into a semiconductor laser.
In order to solve the above technical problem, the present invention provides a large bandwidth chirp signal generation apparatus, including:
a main laser for generating a wavelength-stable and continuous optical carrier signal;
the frequency shift modulation module is connected with the main laser and is used for carrying out frequency modulation on the optical carrier signal with stable and continuous wavelength to obtain the frequency-modulated optical carrier signal;
the light intensity modulation module is connected with the frequency shift modulation module and is used for carrying out intensity modulation on the optical carrier signal after frequency modulation to obtain an optical carrier signal carrying an intensity modulation signal;
the slave laser is connected with the light intensity modulation module through an optical circulator, an optical carrier signal carrying an intensity modulation signal is injected into the slave laser through the optical circulator to excite a single-period oscillation state of the slave laser, and a linear frequency modulation optical carrier signal is output under the influence of the intensity modulation signal;
the photoelectric detection module is connected with the slave laser through the optical circulator and converts a linear frequency modulation optical carrier signal into a linear frequency modulation electric signal to be output;
the frequency shift modulation module performs frequency shift modulation of different frequency differences on optical carrier signals in a continuous time period, so that the slave laser generates linear frequency modulation optical carrier signals with different frequency sweep ranges, and the linear frequency modulation electrical signals output by the photoelectric detection module are spliced in a time domain to obtain linear frequency modulation electrical signals with increased frequency sweep ranges after splicing; the chirp rate of the chirp electrical signals in different sweep frequency ranges is the same, and the frequency of the chirp electrical signals at the end time of the previous time period and the start time of the next time period is the same in the continuous time period.
As a further improvement of the present invention, the frequency shift modulation module is connected to a first modulation signal generator, the first modulation signal generator is configured to generate a preset frequency shift modulation signal and perform frequency shift modulation on the optical carrier signal through the frequency shift modulation module, and the first modulation signal generator is further configured to control a modulation frequency difference and a modulation duration of the optical carrier signal by the frequency shift modulation module.
As a further improvement of the present invention, the light intensity modulation module is connected to a second modulation signal generator, the second modulation signal generator is configured to generate a preset intensity modulation signal, and perform intensity modulation on the optical carrier signal through the light intensity modulation module so as to control a sweep frequency range, a sweep frequency period, and a duty ratio of the chirp signal, where the intensity modulation signal is a voltage signal having a desired waveform, amplitude, period, and duty ratio.
As a further improvement of the present invention, the optical circulator is provided with a first port, a second port and a third port, the first port is connected to the optical intensity modulator to receive the modulated optical carrier signal, the second port is connected to the slave laser, and the third port is connected to the photodetection module.
As a further improvement of the present invention, the photodetection module comprises a photodetector for converting a chirped optical signal generated from a laser into a chirped electrical signal.
A method for generating a large-bandwidth chirp signal uses a large-bandwidth chirp signal generation device as described above to generate a large-bandwidth chirp signal.
As a further improvement of the present invention, the generating of the large-bandwidth chirp signal specifically includes the following steps:
s1, in a time period T1, the optical frequency shift modulation module carries out difference frequency of delta f on a stable and continuous optical carrier signal with wavelength emitted by a main laser 1 Frequency shift modulation;
s2, the optical carrier signal after frequency shift modulation is subjected to intensity modulation through an optical intensity modulation module, and an optical carrier signal carrying an intensity modulation signal U1 (t) is output;
s3, injecting an optical carrier signal carrying an intensity modulation signal U1 (t) into a slave laser through an optical circulator, exciting a single-period oscillation state S1 by the slave laser, and generating a linear frequency modulation optical carrier signal C1 under the influence of the intensity modulation signal U1 (t);
s4, converting the linear frequency modulation optical carrier signal C1 into a linear frequency modulation electrical signal LFM1 through a photoelectric detection module;
s5, next stepIn a time period T2, the optical frequency shift modulation module performs difference frequency of delta f on a stable and continuous optical carrier signal with wavelength emitted by the main laser 2 Frequency shift modulation in which Δ f 1 ≠Δf 2 ；
S6, the optical carrier signal after frequency shift modulation is subjected to intensity modulation through an optical intensity modulation module, and an optical carrier signal carrying an intensity modulation signal U2 (t) is output;
s7, injecting an optical carrier signal carrying an intensity modulation signal U2 (t) into a slave laser through an optical circulator, exciting a single-period oscillation state S2 by the slave laser, and generating a linear frequency modulation optical carrier signal C2 under the influence of the intensity modulation signal U2 (t);
s8, converting the linear frequency modulation optical carrier signal C2 into a linear frequency modulation electric signal LFM2 through a photoelectric detection module;
s9, splicing the linear frequency modulation electric signal LFM1 and the linear frequency modulation electric signal LFM2 on a time domain to obtain a linear frequency modulation electric signal LFM3, wherein the period of the linear frequency modulation electric signal LFM3 is T1+ T2, and the sweep frequency range of the linear frequency modulation electric signal LFM3 is the sweep frequency range after splicing the linear frequency modulation electric signal LFM1 and the linear frequency modulation electric signal LFM 2.
As a further improvement of the invention, the chirp signal LFM1 and the chirp signal LFM2 have the same chirp rate and have the same frequency at the end of the time period T1 and at the beginning of the time period T2.
As a further improvement of the present invention, the chirp rate is a ratio of a frequency to a time of the chirp signal, and the chirp rate of each chirp signal is changed by adjusting a time width of each time period of the chirp signal.
As a further development of the invention, the intensity modulated signal U1 (T) and the intensity modulated signal U2 (T) have different waveforms, amplitudes, periods and duty cycles, so that the chirp signal LFM1 and the chirp signal LFM2 the end of the time period T1 and the moment of the time period T2 start have the same frequency.
The invention has the beneficial effects that: the invention not only controls the intensity of the injected light injected into the semiconductor laser, but also controls the frequency of the injected light, thereby realizing that the slave laser is in a single-period oscillation state with different frequencies at different moments, splicing chirp signals in different frequency sweep ranges generated by different single-period oscillation states on a time domain, and splicing and generating linear chirp signals with the bandwidth of hundreds of G only under the condition of permission of a device, namely the linear frequency modulation optical signal generated by the invention has the advantages of wide sweep frequency band, high linearity and large time bandwidth product, can greatly improve the detection precision of the radar, and has great application potential; the core devices of the device are a commercial single-mode semiconductor laser and a commercial electro-optical modulator, the method has the advantages of simple system structure, low construction cost and simple operation, each module can be miniaturized and integrated and packaged, and the linear frequency modulation signal generating system can be integrated through remote control of a computer program.
Drawings
FIG. 1 is a schematic structural view of the present invention;
FIG. 2 is a block diagram of an embodiment of the present invention;
FIG. 3 is a schematic optical spectrum of the present invention for generating a large broadband chirp signal;
FIG. 4 is a schematic diagram of the present invention for generating a large broadband chirp signal;
FIG. 5 is a schematic diagram of a theoretical simulation result of generating a large broadband chirp signal in accordance with the present invention;
fig. 6 is a graphical representation of the experimental generation of a large broadband chirp signal in accordance with the present invention.
Detailed Description
The present invention is further described below in conjunction with the following figures and specific examples so that those skilled in the art may better understand the present invention and practice it, but the examples are not intended to limit the present invention.
Referring to fig. 1, the present invention provides a large bandwidth chirp signal generation apparatus including:
a main laser for generating a wavelength-stable and continuous optical carrier signal;
the frequency shift modulation module is connected with the main laser and is used for carrying out frequency modulation on the optical carrier signal with stable and continuous wavelength to obtain the frequency-modulated optical carrier signal;
the light intensity modulation module is connected with the frequency shift modulation module and is used for carrying out intensity modulation on the optical carrier signal after frequency modulation to obtain an optical carrier signal carrying an intensity modulation signal;
the slave laser is connected with the light intensity modulation module through an optical circulator, an optical carrier signal carrying an intensity modulation signal is injected into the slave laser through the optical circulator to excite a single-period oscillation state of the slave laser, and a linear frequency modulation optical carrier signal is output under the influence of the intensity modulation signal;
the photoelectric detection module is connected with the slave laser through the optical circulator and converts the linear frequency modulation optical carrier signal into a linear frequency modulation electric signal to be output;
the frequency shift modulation module performs frequency shift modulation of different frequency differences on optical carrier signals in a continuous time period, so that linear frequency modulation optical carrier signals in different frequency sweep ranges are generated from the laser, and linear frequency modulation electric signals output by the photoelectric detection module are spliced in a time domain to obtain linear frequency modulation electric signals with increased frequency sweep ranges after splicing; the chirp rate of the chirp electrical signals in different sweep frequency ranges is the same, and the frequency of the chirp electrical signals at the end time of the previous time period and the start time of the next time period is the same in the continuous time period.
In the using process of the invention, the main laser can generate an optical carrier signal with stable and continuous wavelength (the wavelength can be continuously tuned); the frequency shift modulation module can perform frequency shift modulation of different frequency differences on the optical carrier signal passing through the frequency shift modulation module at different moments under the control of the modulation signal generation module 1, so that the optical carrier signal is subjected to frequency shift modulation of different difference frequencies in different time periods; according to the invention, the frequency shift modulation module comprises a double-parallel MZ modulator, and according to the principle of carrier suppression single-sideband modulation, the double-parallel MZ modulator can be used for carrying out frequency shift modulation on an optical carrier signal; the light intensity modulation module carries out intensity modulation on the laser carrier signal passing through the frequency shift modulation module to obtain a light carrier signal of which the light intensity can be adjusted by the modulation signal generation module 2, and the modulation signal generation module 2 can generate a voltage signal with a specific waveform, amplitude and period to control the frequency sweeping range, the frequency sweeping period and the duty ratio of the linear frequency modulation electric signal generated by the frequency shift modulation device; the slave laser is connected with the optical circulator, the optical circulator injects an optical carrier signal modulated by a modulation signal generated by the modulation signal generation module through the frequency shift modulation module and the light intensity modulation module into the slave laser to excite the single-period oscillation state of the slave laser, and a sweep frequency signal output by the slave laser is transmitted to the photoelectric detection module through the optical circulator; the photoelectric detection module is connected with the optical circulator and converts a linear frequency modulation optical signal output from the laser into a linear frequency modulation electric signal.
The device of the invention has the following advantages:
1. according to the invention, through reasonably and continuously adjusting the frequency detuning between the master laser and the free-running slave laser and the optical power injected into the slave laser by the optical carrier signal, the slave laser outputs the single-period oscillation state in different frequency ranges in different time periods;
2. the frequency shift modulation module can control the frequency difference of the frequency shift modulation of the optical carrier and the modulation time of the frequency shift modulation through the modulation signal generation module, and the frequency shift modulation module enables the optical carrier signal passing through the frequency shift modulation module to generate frequency shift modulation of different frequency differences in different time periods;
3. whether the frequency modulation signal output from the laser single-period oscillation state is a linear frequency modulation signal or not can be accurately controlled in each time period through the voltage signal with the specific waveform preset by the modulation signal generation module 2, and the frequency sweeping range, the frequency sweeping period and the duty ratio of the chirp optical signal can be simply and accurately tuned by adjusting the amplitude and the period of the voltage signal through the modulation signal generation module 2.
Further, the frequency shift modulation module in the present invention needs to ensure that the frequency of the optical carrier signal after frequency shift modulation in the next time period is detuned from the frequency of the slave laser to just enable the slave laser to excite a single-period oscillation state of another frequency range; the modulation signal generation module 2 of the invention needs to respectively generate modulation signals with different waveforms, amplitudes, durations and duty ratios in two continuous time periods, so as to ensure that the linear frequency modulation signals respectively generated in the two time periods after the modulated optical carrier signal is injected into the laser have the same frequency at the time when the previous time period ends and the next time period starts; meanwhile, the chirp rate of the chirp signal generated in a certain time period and the chirp rate of the chirp signal generated in the next time period need to be the same, so that the two chirp signals generated in the continuous time period can be spliced in the time domain, and the bandwidth of the generated chirp signals is enhanced.
Examples
As shown in fig. 2 to fig. 4, the present embodiment provides a large bandwidth chirp signal generation apparatus, and based on the foregoing embodiment, the apparatus specifically includes: the optical attenuator comprises a main laser, an optical attenuator, a double-parallel MZ modulator, an optical circulator, a slave laser and a photoelectric detector; the master laser, the optical attenuator, the double-parallel MZ modulator and the MZ modulator are sequentially connected, the MZ modulator is connected with the slave laser through the optical circulator, and the slave laser is connected with the photoelectric detector through the optical circulator; the double parallel MZ modulator is connected with a signal modulator 1, and the MZ modulator is connected with a signal modulator 2; in this embodiment, the center wavelength of the master laser and the center wavelength of the slave laser are both around 1550nm, the difference between the two frequencies is called "detuned frequency", and the injection of optical carrier signals of different detuned frequencies into the slave laser excites the slave laser into a monocycle oscillation state having a different frequency range.
The working process of the embodiment:
output frequency f of the main laser ML During the time T1, the signal modulator 1 generates a signal modulation signal V1 (T) and transmits the signal modulation signal V1 (T) into a double-parallel MZ modulator (frequency shift modulation module), and the frequency difference of the double-parallel MZ modulator is Δ f 1 The frequency of the optical carrier signal passing through the dual parallel MZ modulator becomes (f) ML +Δf 1 ) (ii) a The signal modulator 2 generates a modulation signal U1 (t) and transmits the modulation signal U1 (t) into an MZ modulator (optical intensity modulator), so that the MZ modulator performs intensity modulation on an optical carrier signal; by passingThe rear frequency of the optical carrier frequency shift modulation module is (f) ML +Δf 1 ) The signal of (2) is injected into the slave laser under the condition of not being modulated by the light intensity modulation module, so that the single-period oscillation state S1 of the slave laser can be excited, and the intensity of the optical carrier signal modulated by the light intensity modulator can change within a certain intensity range delta xi 1= (xi 1, xi 2) along with the amplitude range of U1 (t);
as shown in FIG. 3 (a), the frequency f of the main laser is ML And a free-running slave laser output frequency f SL The continuous optical signal of (a); the signal modulator 2 generates a voltage signal U1 (t) with a specific waveform, the intensity of the optical carrier signal is modulated by the optical intensity modulator, the optical carrier signal after intensity modulation passes through the first port 1 and the second port 2 of the optical circulator and then is injected into the slave laser, the slave laser works in a single-period oscillation state S1 under proper injection power, and the optical signal output from the laser not only comprises a frequency component (f) which is the same as the optical carrier frequency injected into the slave laser ML + Δ f 1), also including a frequency range of Δ f 1 ’＝f s2 -f s1 The linear frequency modulated optical signal of (a), as shown in fig. 3 (b); a linear frequency modulation optical signal generated by a laser is converted into a linear frequency modulation electric signal after passing through a single mode optical fiber and a commercial large-bandwidth photoelectric detector;
in the time period T2, the signal modulator 1 generates a signal modulation signal V2 (T) and transmits the signal modulation signal V2 (T) into a dual parallel MZ modulator (frequency shift modulation module), and the frequency shift modulation module performs a frequency difference Δ f on the optical carrier signal 2 The frequency of the optical carrier signal passing through the frequency shift modulation module becomes (f) ML +Δf 2 ) The optical carrier signal of the frequency is input into the slave laser without being modulated by the optical carrier intensity modulator, and another monocycle oscillation state S2 of the slave laser can be excited; the signal modulator 2 generates a new modulation signal U2 (t) and transmits the new modulation signal into the light intensity modulator, so that the light intensity modulator performs modulation on the optical carrier signal with different intensities, and after the modulation of the optical carrier intensity modulator, the light intensity of the optical carrier signal can change within a certain intensity range delta xi 2= (xi 3, xi 4); the optical carrier signal modulated by the optical intensity modulator passes through a first optical circulatorThe port 1 and the second port 2 are injected into the slave laser, and the slave laser works in a single-period oscillation state S2 under proper injection power, and the output signal of the slave laser not only comprises the frequency component (f) injected into the slave laser ML +Δf 2 ) Also includes a frequency range Δ f 2 ’＝f s3 -f s2 As shown in fig. 3 (c). The linear frequency modulation optical signal is converted into a linear frequency modulation electric signal after passing through a single mode optical fiber and a commercial large-bandwidth photoelectric detector;
respectively generating delta f with the sweep frequency range of T1 and T2 in two periods of time 1 ' and Δ f 2 The linear frequency modulation signal of' generates a period of time width (T1 + T2) and a sweep frequency range (delta f) after being spliced on a time domain 1 ’+Δf 2 ') bandwidth enhanced chirp signal.
The chirp rate of the chirp signals generated in the two periods of time T1 and T2 is the same, and at the time when T1 ends and T2 starts, the two chirp signals have the same frequency, so that the requirements of the two periods of time are strictly met, and the generated chirp signals can obtain large bandwidth and good linearity.
The theoretical simulation result of the method and the apparatus for generating large bandwidth chirp signals related in this embodiment is given by fig. 5, and under the condition that the detuning frequencies are 6GHz and 10GHz, respectively, a large bandwidth chirp signal of 12 to 26GHz formed by splicing two LFM signals of 12 to 16GHz (0-0.8 μ s) and 16 to 26GHz (0.8-2.5 μ s) can be generated theoretically, and the LFM signals generated by other detuning frequencies can be continuously spliced under the condition allowed by the device;
as shown in fig. 6, when the frequency of the output of the master laser is 193.250THz and the free-running frequency of the slave laser is 193.252THz, the frequency shift modulation module performs 8GHz frequency shift modulation on the optical carrier within (1.5-2.5) μ s, the modulated optical carrier frequency is 193.258THz, and the detuning frequency at this time is 6GHz. The optical carrier signal after frequency shift modulation is subjected to intensity modulation through a light intensity modulation module, the modulated optical carrier signal is injected into a slave laser, and a linear frequency sweep signal of 12-16GHz is generated from the slave laser; within (2.5-3.5) mu s, the frequency shift modulation module performs 12GHz frequency shift modulation on the optical carrier, the modulated optical carrier frequency is 193.262THz, and the detuning frequency at the moment is 10GHz. And the optical carrier signal after frequency shift modulation is subjected to intensity modulation through an optical carrier intensity modulation module, the modulated optical carrier signal is injected into a slave laser, and a 16-20GHz linear frequency sweeping signal is generated from the slave laser. Finally, the linear frequency modulation signal with the frequency sweep range of 12-20GHz can be obtained within (1.5-3.5) mu s. It should be noted that due to the bandwidth (0-20 GHz) limitations of the experimental setup, the resulting chirp range is not the actual generated range, which is greater than 20GHz.
By the device and the method, the laser works in a single-period oscillation state, so that the generated linear frequency modulation optical signal has the advantages of large scanning bandwidth, high scanning speed and large time-bandwidth product; furthermore, the master laser, the frequency shift modulation module, the light intensity modulation module, the slave laser and the photoelectric detector in the invention can be miniaturized and can be remotely controlled by a computer program, so that the large-bandwidth linear frequency modulation signal generation method and the device system can be integrated; the laser can adopt a commercial single-mode semiconductor laser, does not need a high-speed radio frequency source, and has the advantages of simple structure, low cost and easy control.
The above-mentioned embodiments are merely preferred embodiments for fully illustrating the present invention, and the scope of the present invention is not limited thereto. The equivalent substitution or change made by the technical personnel in the technical field on the basis of the invention is all within the protection scope of the invention. The protection scope of the invention is subject to the claims.
Claims (10)
1. A large bandwidth chirp signal generation apparatus characterized by: the method comprises the following steps:
a main laser for generating a wavelength-stable and continuous optical carrier signal;
the frequency shift modulation module is connected with the main laser and is used for carrying out frequency modulation on the optical carrier signal with stable and continuous wavelength to obtain the frequency-modulated optical carrier signal;
the light intensity modulation module is connected with the frequency shift modulation module and is used for carrying out intensity modulation on the optical carrier signal after frequency modulation to obtain an optical carrier signal carrying an intensity modulation signal;
the slave laser is connected with the light intensity modulation module through an optical circulator, an optical carrier signal carrying an intensity modulation signal is injected into the slave laser through the optical circulator to excite a single-period oscillation state of the slave laser, and a linear frequency modulation optical carrier signal is output under the influence of the intensity modulation signal;
the photoelectric detection module is connected with the slave laser through the optical circulator and converts a linear frequency modulation optical carrier signal into a linear frequency modulation electric signal to be output;
the frequency shift modulation module performs frequency shift modulation of different frequency differences on optical carrier signals within a continuous time period, so that the slave laser generates linear frequency modulation optical carrier signals of different frequency sweep ranges, and the linear frequency modulation electrical signals output by the photoelectric detection module are spliced on a time domain to obtain linear frequency modulation electrical signals of the spliced frequency sweep range; the chirp rate of the chirp electrical signals in different sweep frequency ranges is the same, and in the continuous time period, the frequencies of the chirp electrical signals at the ending time of the previous time period and the starting time of the next time period are the same.
2. A large bandwidth chirp signal generation device as claimed in claim 1, wherein: the frequency shift modulation module is connected with a first modulation signal generator, the first modulation signal generator is used for generating a preset frequency shift modulation signal and carrying out frequency shift modulation on the optical carrier signal through the frequency shift modulation module, and the first modulation signal generator is also used for controlling the modulation frequency difference and the modulation duration of the frequency shift modulation module on the optical carrier signal.
3. A large bandwidth chirp signal generation device as claimed in claim 1, wherein: the light intensity modulation module is connected with a second modulation signal generator, the second modulation signal generator is used for generating a preset intensity modulation signal and carrying out intensity modulation on the optical carrier signal through the light intensity modulation module so as to control the sweep frequency range, the sweep frequency period and the duty ratio of the linear frequency modulation signal, and the intensity modulation signal is a voltage signal with a required waveform, amplitude, period and duty ratio.
4. A large bandwidth chirp signal generation apparatus as claimed in claim 1, wherein: the optical circulator is provided with a first port, a second port and a third port, the first port is connected with the light intensity modulator to receive modulated optical carrier signals, the second port is connected with the slave laser, and the third port is connected with the photoelectric detection module.
5. A large bandwidth chirp signal generation apparatus as claimed in any one of claims 1 to 4, wherein: the photo detection module includes a photo detector for converting a chirped optical signal generated from a laser into a chirped electrical signal.
6. A method for generating a large bandwidth chirp signal, characterized by: use of a large bandwidth chirp signal generation apparatus as claimed in any one of claims 1 to 5 to generate a large bandwidth chirp signal.
7. A method of generating a large bandwidth chirp signal as claimed in claim 6, wherein: the method for generating the large-bandwidth linear frequency modulation electric signal specifically comprises the following steps:
s1, in a time period T1, the optical frequency shift modulation module carries out difference frequency of delta f on a stable and continuous optical carrier signal with wavelength emitted by a main laser 1 Frequency shift modulation;
s2, the optical carrier signal after frequency shift modulation is subjected to intensity modulation through an optical intensity modulation module, and an optical carrier signal carrying an intensity modulation signal U1 (t) is output;
s3, injecting an optical carrier signal carrying an intensity modulation signal U1 (t) into a slave laser through an optical circulator, exciting a single-period oscillation state S1 by the slave laser, and generating a linear frequency modulation optical carrier signal C1 under the influence of the intensity modulation signal U1 (t);
s4, converting the linear frequency modulation optical carrier signal C1 into a linear frequency modulation electric signal LFM1 through a photoelectric detection module;
s5, in the next time period T2, the optical frequency shift modulation module carries out difference frequency of delta f on the optical carrier signal which is stable and continuous in wavelength and is emitted by the main laser 2 Frequency shift modulation in which Δ f 1 ≠Δf 2 ；
S6, carrying out intensity modulation on the optical carrier signal subjected to frequency shift modulation through an optical intensity modulation module, and outputting an optical carrier signal carrying an intensity modulation signal U2 (t);
s7, injecting an optical carrier signal carrying an intensity modulation signal U2 (t) into a slave laser through an optical circulator, exciting a single-period oscillation state S2 by the slave laser, and generating a linear frequency modulation optical carrier signal C2 under the influence of the intensity modulation signal U2 (t);
s8, converting the linear frequency modulation optical carrier signal C2 into a linear frequency modulation electric signal LFM2 through a photoelectric detection module;
s9, splicing the linear frequency modulation electric signal LFM1 and the linear frequency modulation electric signal LFM2 on a time domain to obtain a linear frequency modulation electric signal LFM3, wherein the period of the linear frequency modulation electric signal LFM3 is T1+ T2, and the sweep frequency range of the linear frequency modulation electric signal LFM3 is the sweep frequency range after splicing the linear frequency modulation electric signal LFM1 and the linear frequency modulation electric signal LFM 2.
8. A method of generating a large bandwidth chirp signal in accordance with claim 7, wherein: the chirp signal LFM1 and the chirp signal LFM2 have the same chirp rate, and have the same frequency at the end of the time period T1 and the beginning of the time period T2.
9. A method of generating a large bandwidth chirp signal as claimed in claim 8 in which: the chirp rate is the ratio of the frequency to the time of the linear frequency modulation electric signals, and the chirp rate of each linear frequency modulation electric signal is changed by adjusting the time width of each time period of the linear frequency modulation electric signals.
10. A method of generating a large bandwidth chirp signal in accordance with claim 8, wherein: the intensity modulated signal U1 (T) and the intensity modulated signal U2 (T) have different waveforms, amplitudes, periods and duty cycles such that the chirp signal LFM1 and the chirp signal LFM2 end the time period T1 and start the time period T2 at the same frequency.
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