Ultra-wideband electromagnetic pulse signal generation device and method based on optical frequency comb

Abstract

The present invention relates to the field of ultra-wideband electromagnetic pulse signal generation, and specifically to an ultra-wideband electromagnetic pulse signal generation device and method based on an optical frequency comb. The optical signal output by the laser is split by a coupler and then enters an optical signal modulation loop. After the polarization state of the optical signal is controlled by a polarization controller and a polarization beam splitter, the optical signal enters an MZM unit to modulate the optical signal. After modulation, the optical signal is amplified by an erbium-doped fiber amplifier, and then output to an optical coupler after amplification. After coupling with the optical signal output by the laser, the optical signal enters the optical signal modulation loop again, and the cycle is repeated multiple times until an optical frequency comb signal with a comb tooth number reaching a target value is generated. The optical frequency comb signal is output to a photodetector through another output end of the optical coupler, and the photodetector outputs a comb carrier signal after beating frequency; the comb carrier signal and a Gaussian pulse broadband signal are mixed by a mixer to obtain an ultra-wideband pulse signal. The present invention is suitable for ultra-wideband electromagnetic pulse signal generation.

Description

Technical Field

[0001] The present invention relates to the field of ultra-wideband electromagnetic pulse signal generation, and in particular to an ultra-wideband electromagnetic pulse signal generation device and method based on an optical frequency comb. Background Art

[0002] With the integration of a large number of components in electronic equipment and the increasingly complex electromagnetic radiation environment, electronic equipment is often interfered by electromagnetic radiation, thus affecting communication or normal operation. The key to solving the electromagnetic compatibility problem of electronic equipment is to conduct electromagnetic sensitivity experimental tests on the equipment, and the electromagnetic radiation sensitivity test is to simulate the complex space electromagnetic environment as much as possible and test the sensitive response of the equipment in the complex electromagnetic environment. Because the electromagnetic radiation in space is extremely complex, an ultra-wideband pulse signal source is required to simulate the electromagnetic emission in the environment. The bandwidth of the signal source is at least DC to 40GHz to stimulate the radiation sensitive response of the test product, test the sensitive frequency points of the equipment and protect them. Therefore, an ultra-wideband pulse signal source with full coverage of DC to 40GHz is the key to realizing electromagnetic sensitivity testing.

[0003] Traditional methods of generating ultra-wideband signal sources usually include Marx circuit method, local oscillator method, optical heterodyne method, etc. The Marx circuit based on avalanche transistor cascade breaks down the 100-level avalanche transistor cascade step by step to generate a Gaussian signal with a pulse width of 0.5ns, which can achieve a DC-1GHz bandwidth in the frequency domain. Since a large number of capacitors are discharged in a short time in this method, the extremely short rising edge achieved by the step-by-step breakdown of the avalanche transistors makes the generated pulse have a serious tail, and it is difficult to break through a higher bandwidth. The local oscillator method based on point-frequency local oscillators and broadband local oscillators uses broadband signals to first point frequency, then multiply frequency, and then multi-level frequency conversion. This method can widen low-frequency signals to high-frequency bands to generate broadband signals, but the signal spectrum generated by this method is discrete and cannot generate a continuous broadband signal. The optical heterodyne rule is to modulate a broadband signal onto an optical signal, and then beat the frequency with another single-wavelength optical signal to move the original broadband signal spectrum to a higher frequency band. This method generates a high-frequency broadband signal, but in essence it moves the spectrum of the broadband signal to a higher frequency band and does not achieve the effect of spectrum broadening. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide an ultra-wideband electromagnetic pulse signal generation device and method based on an optical frequency comb, which realizes the frequency domain broadening of a continuous broadband signal and generates an ultra-wideband signal with a continuous spectrum.

[0005] The present invention adopts the following technical solutions to achieve the above-mentioned purpose. In a first aspect, the present invention provides an ultra-wideband electromagnetic pulse signal generating device based on an optical frequency comb, comprising:

[0006] It includes a laser 1, an optical coupler 3, an erbium-doped fiber amplifier 4, an MZM (Mach-Zehnder Modulator) unit 5, a polarization beam splitter 7, a polarization controller 8, an optical attenuator 9, a photodetector 10, a mixer 11, a radio frequency signal source 12, a spectrum analyzer 14, a Gaussian pulse broadband signal source 15 and a controller 13, wherein the optical coupler 3, the polarization controller 8, the polarization beam splitter 7, the MZM unit 5 and the erbium-doped fiber amplifier 4 constitute an optical signal modulation loop;

[0007] The optical coupler 3 includes two input ends and two output ends, the laser 1 is connected to one input end of the optical coupler, the other input end of the optical coupler 3 is connected to the output end of the erbium-doped fiber amplifier 4, one output end of the optical coupler 3 is connected to the MZM unit 5 through the polarization controller 8 and the polarization beam splitter 7 in sequence, the MZM unit 5 is connected to the input end of the erbium-doped fiber amplifier 4, the other output end of the optical coupler 3 is connected to one input end of the mixer 11 through the optical attenuator 9 and the photodetector 10 in sequence, the other input end of the mixer 11 is connected to the Gaussian pulse broadband signal source 15, one end of the controller 13 is connected to the Gaussian pulse broadband signal source 15 through the spectrum analyzer 14, the other end of the controller 13 is connected to the radio frequency signal source 12, and the radio frequency signal source 12 sends a radio frequency signal to the MZM unit 5;

[0008] The optical signal output by the laser 1 is split by the coupler 3, and then enters the optical signal modulation loop. After the polarization state of the optical signal is controlled by the polarization controller 8 and the polarization beam splitter 7 in the optical signal modulation loop, the optical signal enters the MZM unit 5 to modulate the optical signal. After modulation, the optical signal is amplified by the erbium-doped fiber amplifier 4, and then output to the optical coupler 3. After coupling with the optical signal output by the laser 1, the optical signal enters the optical signal modulation loop again, and the cycle is repeated many times until an optical frequency comb signal with a comb tooth number reaching a target value is generated. The optical frequency comb signal is output to the photodetector 10 through the other output end of the optical coupler 3, and the photodetector 10 outputs a comb carrier signal after the beat frequency.

[0009] The controller 13 selects the optimal RF signal frequency and sets the RF signal frequency of the RF signal source 12 to the optimal RF signal frequency, then regenerates the optical frequency comb signal based on the optical signal modulation loop, and outputs the corresponding comb carrier signal through the photodetector 10, and finally mixes the comb carrier signal and the Gaussian pulse broadband signal through the mixer 11 to obtain an ultra-wideband pulse signal.

[0010] Furthermore, the controller 13 selects the optimal RF signal frequency specifically including:

[0011] The controller 13 receives the Gaussian pulse broadband signal collected by the spectrum analyzer 14, and calculates the bandwidth of the Gaussian pulse broadband signal, and calculates the spectrum distribution of the ultra-wideband pulse signal after mixing according to the calculated bandwidth and the comb carrier signal generated by the optical signal modulation loop. The variable range of the RF signal frequency is determined by judging the spectrum flatness of the spectrum distribution. Within the variable range, the frequency of the RF signal is swept and simulated, and the flatness of the ultra-wideband signal generated by mixing the comb carrier signal generated by the optical signal modulation loop and the Gaussian pulse signal at different frequencies is calculated, and the optimal RF signal frequency is selected according to the flatness.

[0012] Furthermore, the MZM unit is a two-stage cascaded MZM, including a first-stage MZM5-1 and a second-stage MZM5-2. By adjusting the relationship between the bias voltage and the half-wave voltage input at both ends of the first-stage MZM5-1 and the second-stage MZM5-2, the first-stage MZM5-1 and the second-stage MZM5-2 both operate at the minimum transmission point.

[0013] Furthermore, the device also includes an optical isolator 2 , and the laser 1 is connected to an input end of the optical coupler 3 via the optical isolator 2 .

[0014] Furthermore, the device also includes an optical fiber delay line 6 , which is connected between the polarization beam splitter 7 and the MZM unit 5 .

[0015] In a second aspect, the present invention provides a method for generating an ultra-wideband electromagnetic pulse signal based on an optical frequency comb, which is applied to the ultra-wideband electromagnetic pulse signal generating device based on an optical frequency comb as described above, comprising:

[0016] The optical signal output by the laser is sent to the optical coupler for splitting. The split optical signal enters the optical signal modulation loop. After the polarization state of the optical signal is controlled by the polarization controller and the polarization beam splitter in the optical signal modulation loop, the optical signal enters the MZM unit through the optical fiber delay line to modulate the optical signal. After modulation, the optical signal is amplified by the erbium-doped fiber amplifier. After amplification, the optical signal is output to the optical coupler, coupled with the optical signal output by the laser, and enters the optical signal modulation loop again. The cycle is repeated many times until an optical frequency comb signal with a comb tooth number reaching a target value is generated.

[0017] The optical frequency comb signal is sent to a photodetector, and the optical frequency comb signal is beat into an electrical signal by the photodetector to generate a comb carrier signal;

[0018] The optimal RF signal frequency is selected by the controller, and the RF signal frequency of the RF signal source is set to the optimal RF signal frequency. Then, the optical frequency comb signal is regenerated based on the optical signal modulation loop, and the corresponding comb carrier signal is output through the photodetector. Finally, the comb carrier signal and the Gaussian pulse broadband signal are mixed by the mixer to obtain an ultra-wideband pulse signal.

[0019] Furthermore, selecting the optimal RF signal frequency by the controller specifically includes:

[0020] A Gaussian pulse broadband signal collected by a spectrum analyzer is received by a controller, and the bandwidth of the Gaussian pulse broadband signal is calculated. A time domain diagram and a spectrum diagram of the ultra-wideband pulse signal after mixing are calculated based on the calculated bandwidth and a comb carrier signal generated by an optical signal modulation loop. The variable range of the radio frequency signal frequency is determined by judging the spectrum flatness of the spectrum diagram. Within the variable range, a frequency sweep simulation is performed on the frequency of the radio frequency signal. The flatness of the ultra-wideband signal generated by mixing the comb carrier signal generated by the optical signal modulation loop and the Gaussian pulse signal at different frequencies is calculated, and the optimal radio frequency signal frequency is selected based on the flatness.

[0021] The beneficial effects of the present invention are:

[0022] The present invention focuses the bandwidth expansion of broadband signals on a tunable optical frequency comb, breaking through the limitations of traditional methods of using point-frequency local oscillators and frequency-multiplied local oscillators to achieve discrete frequency expansion in the frequency domain, and generates an ultra-wideband signal with a continuous spectrum.

[0023] The present invention widens the Gaussian pulse broadband signal in the frequency domain, mixes the DC-1GHz continuous bandwidth into the high frequency range, realizes the frequency domain widening of the continuous broadband signal, and generates an ultra-wideband electromagnetic signal.

[0024] The present invention controls the comb tooth interval of a comb carrier signal so that the comb carrier signal and a Gaussian pulse signal are mixed to generate an ultra-wideband pulse signal with flat frequency domain, and provides a calculation method for a controller to obtain the optimal comb teeth of a radio frequency signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic structural diagram of an ultra-wideband electromagnetic pulse signal generating device based on an optical frequency comb provided by an embodiment of the present invention;

[0026] Figure 2 is a spectrum diagram of a comb carrier signal provided by an embodiment of the present invention;

[0027] Figure 3 is a time domain diagram of a collected Gaussian pulse broadband signal provided by an embodiment of the present invention;

[0028] Figure 4 is a time domain diagram of an ultra-wideband signal generated by frequency mixing provided by an embodiment of the present invention;

[0029] Figure 5 is a frequency domain diagram of an ultra-wideband signal generated by frequency mixing provided by an embodiment of the present invention;

[0030] Figure 6is a time domain diagram of an ultra-wideband signal generated by mixing down the optimal radio frequency signal frequency provided by an embodiment of the present invention;

[0031] Figure 7 It is a frequency domain diagram of an ultra-wideband signal generated by mixing down the optimal radio frequency signal frequency provided by an embodiment of the present invention.

[0032] In the accompanying drawings, 1 represents a laser, 2 represents an optical isolator, 3 represents an optical coupler, 4 represents an erbium-doped fiber amplifier, 5 represents an MZM unit, 5-1 represents a first-stage MZM, 5-2 represents a second-stage MZM, 6 represents an optical fiber delay line, 7 represents a polarization beam splitter, 8 represents a polarization controller, 9 represents an optical attenuator, 10 represents a photodetector, 11 represents a mixer, 15 represents a Gaussian pulse broadband signal source, 13 represents a controller, 12 represents a radio frequency signal source, and 14 represents a spectrum analyzer. DETAILED DESCRIPTION

[0033] To make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0034] The present invention provides an ultra-wideband electromagnetic pulse signal generating device based on an optical frequency comb, such as Figure 1 As shown, it includes a laser 1, an optical isolator 2, an optical coupler 3, an erbium-doped fiber amplifier 4, an MZM unit 5, an optical fiber delay line 6, a polarization beam splitter 7, a polarization controller 8, an optical attenuator 9, a photodetector 10, a mixer 11, a radio frequency signal source 12, a spectrum analyzer 14, a Gaussian pulse broadband signal source 15 and a controller 13, wherein the optical coupler 3, the polarization controller 8, the polarization beam splitter 7, the optical fiber delay line 6, the MZM unit 5 and the erbium-doped fiber amplifier 4 constitute an optical signal modulation loop, and the optical power meter is suitable for measuring the power of the signal of the polarization beam splitter 7 to adjust the polarization controller and control the polarization state of the signal;

[0035] The optical coupler 3 includes two input ends and two output ends. The laser 1 is connected to one input end of the optical coupler through the optical isolator 2. The other input end of the optical coupler 3 is connected to the output end of the erbium-doped fiber amplifier 4. One output end of the optical coupler 3 is connected to the MZM unit 5 through the polarization controller 8, the polarization beam splitter 7, and the optical fiber delay line 6 in sequence. The MZM unit 5 is connected to the input end of the erbium-doped fiber amplifier 4. The other output end of the optical coupler 3 is connected to one input end of the mixer 11 through the optical attenuator 9 and the photodetector 10 in sequence. The other input end of the mixer 11 is connected to a Gaussian pulse broadband signal source 15. One end of the controller 13 is connected to the Gaussian pulse broadband signal source 15 through the spectrum analyzer 14. The other end of the controller 13 is connected to the radio frequency signal source 12. The radio frequency signal source 12 sends a radio frequency signal to the MZM unit 5.

[0036] The optical signal output by the laser 1 passes through the optical isolator 2 and is split by the coupler 3. After the splitting, it enters the optical signal modulation loop. In the optical signal modulation loop, the polarization state of the optical signal is controlled by the polarization controller 8 and the polarization beam splitter 7. Then, it enters the MZM unit 5 through the optical fiber delay line 6 to modulate the optical signal. After modulation, the optical signal is amplified by the erbium-doped fiber amplifier 4. After amplification, it is output to the optical coupler 3, and after coupling with the optical signal output by the laser 1, it enters the optical signal modulation loop again. The cycle is repeated many times until an optical frequency comb signal with a comb tooth number reaching a set target value is generated. The optical frequency comb signal is output to the photodetector 10 through another output end of the optical coupler 3. The photodetector 10 outputs a comb carrier signal after the beat frequency.

[0037] The controller 13 receives the Gaussian pulse broadband signal collected by the spectrum analyzer 14, and calculates the bandwidth of the Gaussian pulse broadband signal, and calculates the time domain diagram and spectrum diagram of the ultra-wideband pulse signal after mixing according to the calculated bandwidth and the comb carrier signal generated by the optical signal modulation loop. The variable range of the RF signal frequency is determined by judging the spectrum flatness of the spectrum diagram. Within this variable range, the frequency of the RF signal is swept and simulated, and the flatness of the ultra-wideband signal generated by mixing the comb carrier signal generated by the optical signal modulation loop and the Gaussian pulse signal at different frequencies is calculated, and the optimal RF signal frequency is selected according to the flatness.

[0038] Then, the optimal RF signal frequency is selected, and the RF signal frequency of the RF signal source 12 is set to the optimal RF signal frequency. Then, the optical frequency comb signal is regenerated based on the optical signal modulation loop, and the corresponding comb carrier signal is output through the photodetector 10. Finally, the comb carrier signal and the Gaussian pulse broadband signal are mixed through the mixer 11 to obtain an ultra-wideband pulse signal.

[0039] In the embodiment of the present invention, the optical signal output by the laser 1 passes through the optical isolator 2 and is split by the coupler 3. Usually, one path enters the optical signal modulation loop, and the other path reaches the photodetector through the optical attenuator. However, the laser outputs a single-wavelength optical signal, which will only output a DC component after directly entering the photodetector, and cannot generate a broadband pulse signal. Since the optical signal transmission is fast and the link optical fiber is short, it can be basically considered that the optical frequency comb signal is generated in a very short time through the optical signal modulation loop, and the optical frequency comb signal reaches the photodetector.

[0040] In one embodiment of the present invention, the MZM unit is a two-stage cascaded MZM, including a first-stage MZM5-1 and a second-stage MZM5-2. By adjusting the relationship between the bias voltage and the half-wave voltage input at both ends of the first-stage MZM5-1 and the second-stage MZM5-2, the first-stage MZM5-1 and the second-stage MZM5-2 both operate at the minimum transmission point.

[0041] Specifically, first, a laser is used to generate a frequency f c The optical signal with frequency f c The optical signal passes through the optical isolator, splits by the 2x2 optical coupler, enters the optical signal modulation loop, and after the polarization state of the light is controlled by the polarization controller and polarization beam splitter, it passes through the optical fiber delay line and enters the two-stage cascaded MZM to modulate the signal.

[0042] The RF signal frequency of the two-stage cascaded MZM is f m By adjusting the relationship between the bias voltage and the half-wave voltage at both ends of the MZM input, the two-stage MZM works at the minimum transmission point. The MZM obtains the first-order sideband of the carrier signal under small signal modulation, and the frequencies are f c +f m , f c -f m , after passing through the second stage MZM, the output is f c +2f m ,f c -2f m The first-order sideband of the comb can be generated by amplifying it and looping it many times to generate a comb spacing of 2f m , the number of teeth is N, the bandwidth is 2Nf m A flat optical frequency comb.

[0043] The generated optical frequency comb is input to a photodetector and its beat frequency is set to a bandwidth ranging from DC to Nf. m , the comb teeth spacing is 2f m The comb carrier signal.

[0044] The controller collects the measured Gaussian pulse broadband signal and calculates the bandwidth of the Gaussian pulse broadband signal. According to the bandwidth of the existing Gaussian pulse broadband signal and the loop, the comb carrier signal is generated to simulate and calculate the time domain diagram and spectrum diagram of the ultra-wideband pulse signal after mixing. By judging the spectrum flatness, the variable range of the frequency of the RF signal is determined (generally 0.5 to 1.5 times the bandwidth of the Gaussian pulse signal when the flatness is good). The frequency of the RF signal is swept and simulated to calculate the flatness of the ultra-wideband signal generated by mixing the comb carrier signal and the measured Gaussian pulse signal at different frequencies. The optimal RF signal frequency f is selected according to the flatness. n The Gaussian pulse broadband signal source of the present invention is generated based on a Marx circuit of 100-level avalanche transistor cascade, and can generate a Gaussian pulse broadband signal with a full-bottom pulse width of less than 0.5ns and a 3dB bandwidth of up to about 1GHz.

[0045] Set the frequency of the RF signal to f n , regenerate the comb teeth interval based on the loop to 2f nThe optical frequency comb is used to generate a comb carrier signal through a photodetector.

[0046] A mixer is used to mix the comb carrier signal and the Gaussian pulse broadband signal, and the Gaussian pulse is mixed to the frequency band of the comb carrier signal to obtain an ultra-wideband pulse signal.

[0047] The tunable laser of the present invention generates 193.1THz with a power of 20dB m The optical signal enters the coupler after passing through the isolator. The splitting ratio of the coupler is 5:5. The polarization state of the optical signal is controlled by the polarization controller and the polarization beam splitter. After being delayed by 600ps in the optical fiber delay line, it enters the MZM. The modulation signal of the MZM is a sine signal with a frequency of 1GHz. Adjust the MZMV bias1 and v bias2 Bias voltage, when v bias1 -v bias2 =v π Yes, MZM works at the minimum transmission point. Under small signal modulation, MZM only generates the first-order sideband. Similarly, after the second-stage MZM, the spectrum lines with frequencies of 193.1THz+2GHz and 193.1THz-2GHz are generated, and after EDFA amplification, they enter the next cycle. A flat optical frequency comb with a center frequency of 193.1THz and a comb tooth spacing of 2GHz is generated through a loop.

[0048] The optical signal and RF signal output by the laser are expressed as:

[0049] v1(t)=v e cos(ω m t), v2(t)=v e cos(ω m t+θ)

[0050] The output signal of the MZM unit after one cycle is:

[0051] E2(t)∝E in (t)J1(β1)J1(β1){cos[(ω0-2ω m )t]+cos[(ω0+2ω m )t]}

[0052] in, v π is the half-wave voltage of the modulator. After multiple cycles, a sparse tooth spacing of 2ω can be generated. m Optical frequency comb.

[0053] The optical frequency comb generated in the optical signal modulation loop is beat to DC-40GHz by the photodetector, and a comb signal with a bandwidth of DC-40GHz and a comb tooth spacing of 2GHz is obtained. The spectrum diagram of the comb carrier signal is as follows Figure 2 shown.

[0054] The broadband signal is a Gaussian pulse broadband signal generated by a Marx circuit. The full-bottom pulse width is less than 0.5ns, and the 3dB bandwidth can reach 1GHz. The time domain diagram of the measured Gaussian pulse broadband signal is as follows: Figure 3 shown.

[0055] Since the flatness of the comb carrier signal is better when the frequency of the RF signal is larger, and the flatness of the broadband signal after mixing will deteriorate when the frequency is too large and the bandwidth of the measured Gaussian pulse signal does not match, the controller is mainly used to collect and calculate the RF signal frequency value with the best flatness of the ultra-wideband signal. After the comb carrier signal based on the optical link is generated, it can be determined that the parameter settings of each component of the optical link can generate a relatively ideal flat and uniform comb carrier signal. On this basis, it is necessary to first calculate the frequency of the optimal RF signal through the controller. The spectrum analyzer is connected to the computer controller through the USB interface, and receives the data collected by the spectrum analyzer through the driver. After the computer controller receives the measured Gaussian pulse broadband signal, the controller collects the measured signal of the Gaussian pulse broadband signal, and calculates the spectrum of the ultra-wideband signal after mixing the measured Gaussian pulse broadband signal and the comb carrier signal at the current RF signal frequency. The indicator of the ultra-wideband signal spectrum flatness characteristic described in the present invention is 15dB bandwidth, that is, the bandwidth of the spectrum range that is 15dB less than the peak power in the spectrum diagram. The upper and lower limits f of the frequency sweep are defined in the computer controller. min ,f max and step length Δf, and search for the RF signal frequency with the best UWB signal performance within a certain range by frequency sweeping.

[0056] The comb carrier signal generated by the optical signal modulation loop is a comb carrier signal with a comb spacing of 2 GHz generated by the drive of a 1 GHz frequency RF signal. The time domain and frequency domain diagrams of the ultra-wideband signal generated by mixing the Gaussian pulse broadband signal and the comb carrier signal are shown in the following figure. Figure 4 and Figure 5 As shown in the figure, the 15dB bandwidth is 26.6GHz. The frequency range and step size of the input RF signal are 0.5GHz~1.5GHz and 1MHz respectively. Through the calculation of the controller, the frequency of the RF signal with the largest 15dB bandwidth is 0.81GHz. The frequency of the RF signal is set to 0.81GHz, and a comb carrier signal with a comb spacing of 1.62GHz is generated. The time domain and frequency domain diagrams of the ultra-wideband signal generated by mixing are shown in the figure below. Figure 6 and Figure 7 As shown, it can be seen that the 15dB bandwidth in the spectrum diagram reaches 40GHz, and the frequency domain flatness is better.

[0057] Through the above process, the present invention generates an ultra-wideband electromagnetic pulse signal with a relatively flat bandwidth range of DC-40GHz.

[0058] The most significant feature of the present invention is that a comb carrier signal with uniformly adjustable comb tooth spacing and a Gaussian pulse broadband signal are used for mixing. The spectrum flatness of the ultra-wideband signal generated by mixing mainly depends on the flatness of the comb carrier signal, the comb tooth spacing of the comb carrier signal and the size relationship of the Gaussian pulse signal bandwidth.

[0059] Therefore, the present invention utilizes the cascaded MZM in the loop to continuously perform cyclic frequency shift, and in each cycle only the first-order sideband of the carrier is retained and amplified to the power of the seed light source to generate a tunable and relatively flat comb carrier signal; in the present invention, data of the Gaussian pulse broadband signal is collected, and the controller is used to simulate and calculate the ultra-wideband signal generated by mixing the comb carrier signal generated by the MZM loop and the measured Gaussian pulse broadband signal, and the frequency of the RF signal when the flatness of the ultra-wideband signal is optimal is calculated by simulating the frequency sweep of the RF signal within a certain range. The flatness of the comb carrier signal is cleverly controlled, and the adaptability of the baseband signal bandwidth and the comb tooth spacing of the carrier signal used for mixing is also controlled to ensure the generation of an ultra-wideband pulse signal with good flatness. The present invention can widen a Gaussian pulse signal with a bandwidth of DC to 1GHz to a frequency domain of DC to 40GHz, and can generate a broadband signal with a continuous spectrum for electromagnetic radiation sensitivity testing. The generation method proposed in the present invention is simple and operable, and the cyclic frequency shift method based on the electro-optical frequency comb has a simple structure, strong stability, and flexible and tunable comb tooth spacing. By controlling the parameters of components and the frequency of the RF signal, the frequency domain flatness of the ultra-wideband signal obtained after mixing can be further optimized.

[0060] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. An ultra-wideband electromagnetic pulse signal generating device based on an optical frequency comb, characterized in that: The invention comprises a laser (1), an optical coupler (3), an erbium-doped fiber amplifier (4), an MZM unit (5), a polarization beam splitter (7), a polarization controller (8), an optical attenuator (9), a photodetector (10), a mixer (11), a radio frequency signal source (12), a spectrum analyzer (14), a Gaussian pulse broadband signal source (15) and a controller (13), wherein the optical coupler (3), the polarization controller (8), the polarization beam splitter (7), the MZM unit (5) and the erbium-doped fiber amplifier (4) constitute an optical signal modulation loop; The optical coupler (3) comprises two input ends and two output ends, the laser (1) is connected to one input end of the optical coupler, the other input end of the optical coupler (3) is connected to the output end of the erbium-doped fiber amplifier (4), one output end of the optical coupler (3) is connected to the MZM unit (5) through the polarization controller (8) and the polarization beam splitter (7) in sequence, the MZM unit (5) is connected to the input end of the erbium-doped fiber amplifier (4), the other output end of the optical coupler (3) is connected to one input end of the mixer (11) through the optical attenuator (9) and the photodetector (10) in sequence, the other input end of the mixer (11) is connected to a Gaussian pulse broadband signal source (15), one end of the controller (13) is connected to the Gaussian pulse broadband signal source (15) through the spectrum analyzer (14), the other end of the controller (13) is connected to the radio frequency signal source (12), and the radio frequency signal source (12) sends a radio frequency signal to the MZM unit (5); The optical signal output by the laser (1) is split by an optical coupler (3) and enters an optical signal modulation loop after the splitting. After the polarization state of the optical signal is controlled by a polarization controller (8) and a polarization beam splitter (7) in the optical signal modulation loop, the optical signal enters an MZM unit (5) to modulate the optical signal. After the modulation, the optical signal is amplified by an erbium-doped fiber amplifier (4). After the amplification, the optical signal is output to the optical coupler (3), and after coupling with the optical signal output by the laser (1), the optical signal enters the optical signal modulation loop again. The cycle is repeated for multiple times until an optical frequency comb signal with a comb tooth number reaching a target value is generated. The optical frequency comb signal is output to a photodetector (10) through another output end of the optical coupler (3). The photodetector (10) outputs a comb carrier signal after the beat frequency. The controller (13) selects an optimal radio frequency signal frequency, sets the radio frequency signal frequency of the radio frequency signal source (12) to the optimal radio frequency signal frequency, then regenerates an optical frequency comb signal based on an optical signal modulation loop, outputs a corresponding comb carrier signal through a photodetector (10), and finally mixes the comb carrier signal and the Gaussian pulse broadband signal through a mixer (11) to obtain an ultra-wideband pulse signal; The controller (13) receives the Gaussian pulse broadband signal collected by the spectrum analyzer (14), calculates the bandwidth of the Gaussian pulse broadband signal, simulates and calculates the spectrum distribution of the ultra-wideband pulse signal after mixing based on the calculated bandwidth and the comb carrier signal generated by the optical signal modulation loop, determines the variable range of the radio frequency signal frequency by judging the spectrum flatness of the spectrum distribution, performs frequency sweep simulation on the frequency of the radio frequency signal within the variable range, calculates the flatness of the ultra-wideband signal generated by mixing the comb carrier signal generated by the optical signal modulation loop and the Gaussian pulse signal at different frequencies, and selects the optimal radio frequency signal frequency based on the flatness.

2. The ultra-wideband electromagnetic pulse signal generating device based on optical frequency comb according to claim 1, characterized in that: The MZM unit is a two-stage cascaded MZM, including a first-stage MZM (5-1) and a second-stage MZM (5-2). By adjusting the relationship between the bias voltage and the half-wave voltage input at both ends of the first-stage MZM (5-1) and the second-stage MZM (5-2), the first-stage MZM (5-1) and the second-stage MZM (5-2) both work at the minimum transmission point.

3. The ultra-wideband electromagnetic pulse signal generating device based on optical frequency comb according to claim 1, characterized in that: The device also includes an optical isolator (2), and the laser (1) is connected to an input end of an optical coupler (3) via the optical isolator (2).

4. The ultra-wideband electromagnetic pulse signal generating device based on optical frequency comb according to claim 1, characterized in that: The device also includes an optical fiber delay line (6), which is connected between the polarization beam splitter (7) and the MZM unit (5).

5. A method for generating an ultra-wideband electromagnetic pulse signal based on an optical frequency comb, applied to an ultra-wideband electromagnetic pulse signal generating device based on an optical frequency comb as claimed in any one of claims 1 to 4, characterized in that: include: The optical signal output by the laser is sent to the optical coupler for splitting. The split optical signal enters the optical signal modulation loop. After the polarization state of the optical signal is controlled by the polarization controller and the polarization beam splitter in the optical signal modulation loop, the optical signal enters the MZM unit through the optical fiber delay line to modulate the optical signal. After modulation, the optical signal is amplified by the erbium-doped fiber amplifier. After amplification, the optical signal is output to the optical coupler, coupled with the optical signal output by the laser, and enters the optical signal modulation loop again. The cycle is repeated many times until an optical frequency comb signal with a comb tooth number reaching a target value is generated. The optical frequency comb signal is sent to a photodetector, and the optical frequency comb signal is beat into an electrical signal by the photodetector to generate a comb carrier signal; The optimal RF signal frequency is selected by a controller, and the RF signal frequency of the RF signal source is set to the optimal RF signal frequency. Then, an optical frequency comb signal is regenerated based on the optical signal modulation loop, and a corresponding comb carrier signal is output through a photodetector. Finally, the comb carrier signal and the Gaussian pulse broadband signal are mixed by a mixer to obtain an ultra-wideband pulse signal. A Gaussian pulse broadband signal collected by a spectrum analyzer is received by a controller, and the bandwidth of the Gaussian pulse broadband signal is calculated. The spectrum distribution of the ultra-wideband pulse signal after mixing is calculated based on the calculated bandwidth and the comb carrier signal generated by the optical signal modulation loop. The variable range of the radio frequency signal frequency is determined by judging the spectrum flatness of the spectrum distribution. Within the variable range, the frequency of the radio frequency signal is swept and simulated, and the flatness of the ultra-wideband signal generated by mixing the comb carrier signal generated by the optical signal modulation loop and the Gaussian pulse signal at different frequencies is calculated. The optimal radio frequency signal frequency is selected according to the flatness.

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