Broadband optical beamforming network and phased array radar based on dual optical frequency combs

Abstract

This application discloses a broadband optical beamforming network, method, and phased array radar based on dual optical frequency combs. The network includes: a light source for outputting continuous light; a first optical frequency comb generation module for utilizing the continuous light to generate a first optical frequency comb signal with a first repetition frequency; a second optical frequency comb generation module for utilizing the continuous light to generate a second optical frequency comb signal with a second repetition frequency; an electro-optical modulation module for modulating a linear frequency modulation wave signal of a preset pulse width onto the first optical frequency comb signal to generate a first modulation signal; and an output module for filtering and photoelectrically detecting the first modulation signal and the second optical frequency comb signal after coupling, thereby frequency-shifting and phase-shifting the linear frequency modulation wave signal and outputting a delayed microwave signal after broadband optical beamforming. This application eliminates the use of optical delay lines, resolving the issues of large system size and difficulty in delay control that exist in broadband optical beamforming networks.

Description

Technical Field

[0001] The present application relates to the technical field of optically controlled beamforming, and in particular to a broadband optically controlled beamforming network, method, and phased array radar based on dual optical frequency combs. Background Art

[0002] Traditional mechanical scanning radars are no longer suitable for new detection missions due to their slow scanning speed, large size, and poor stability. They have been replaced by phased array radars, which offer advantages such as fast scanning speed, conformal conformity with the radar platform, high stability, and strong waveform agility. The flexible and versatile detection capabilities of phased array radars have led to their widespread application.

[0003] Radar detection primarily operates in four dimensions: azimuth, elevation, longitudinal, and Doppler. The azimuth and elevation detection resolutions, along with target range, determine the radar's lateral resolution. Radar's lateral detection resolution and Doppler resolution are primarily increased by illuminating the target for a longer period of time. However, the radar's longitudinal detection resolution is inversely proportional to the transmitted signal bandwidth. Increasing the transmitted signal bandwidth can improve both longitudinal resolution and detection accuracy. Therefore, using broadband radar signals is highly beneficial for ranging and imaging.

[0004] To combine the flexible detection capabilities of phased array radars with the high-resolution detection capabilities of wideband radars, researchers have begun conducting in-depth research on wideband phased array radars. However, traditional phased array radars are narrowband systems, and the aperture effect affects the instantaneous bandwidth and beam pointing of the transmitted signal, making them unsuitable for transmitting wideband radar signals. Therefore, the technical approach for wideband phased array radars cannot be directly applied to traditional phased array radars. Currently, there are two relevant technical approaches: real-time delay compensation technology and adaptive beamforming technology. Numerous implementations of real-time delay compensation technology exist, such as digital delay lines, fractional delay filters, optical delay lines, and frequency- and phase-shift delay methods for linear frequency modulated waves. Optical delay lines, with their advantages of low loss, light weight, and electromagnetic interference resistance, have become a research hotspot. However, existing optical delay line solutions typically only offer discrete adjustment for large delays, while those that offer continuous delay adjustment only offer smaller delays. Practical optical delay line solutions are still under development. Adaptive beamforming technology is mainly used in receivers. It can adjust the spatial beam shape in real time and is suitable for situations with strong interference and weak targets. However, the adaptive beamforming solution has the problem of excessive computational complexity when the array scale is expanded.

[0005] It can be seen that how to develop a broadband optical beamforming network solution with simple structure and easy scalability is still an urgent problem to be solved. Summary of the Invention

[0006] The present application provides a broadband optical beamforming network, method, and phased array radar based on dual optical frequency combs to solve the problems of large system size and difficult delay control in broadband optical beamforming networks in related technologies.

[0007] In a first aspect, an embodiment of the present application provides a broadband optically controlled beamforming network based on a dual optical frequency comb, comprising the following modules: a light source for outputting continuous light; a first optical frequency comb generating module for generating a first optical frequency comb signal with a first repetition frequency using the continuous light; a second optical frequency comb generating module for generating a second optical frequency comb signal with a second repetition frequency using the continuous light; an electro-optical modulation module for modulating a linear frequency modulated wave signal with a preset pulse width onto the first optical frequency comb signal to generate a first modulation signal; and an output module for filtering and photoelectrically detecting the first modulation signal and the second optical frequency comb signal after coupling, so as to frequency-shift and phase-shift the linear frequency modulated wave signal, and output a delayed microwave signal after broadband optically controlled beamforming.

[0008] Optionally, in one embodiment of the present application, it further includes: a linear frequency modulation wave source, used to generate a linear frequency modulation wave signal of the preset pulse width, and input the linear frequency modulation wave signal of the preset pulse width to the electro-optical modulation module.

[0009] Optionally, in one embodiment of the present application, it further includes: a phase compensation module, which is connected to the output end of the second optical frequency comb generation module and is used to add a phase shift to each comb tooth of the second optical frequency comb signal to obtain the phase required by the linear frequency modulation wave signal.

[0010] Optionally, in one embodiment of the present application, the output module includes: a coupler for coupling the first modulated signal and the second optical frequency comb signal; an optical filter group for filtering the coupled signal; and a photodetector group for photoelectrically detecting the filtered signal.

[0011] Optionally, in one embodiment of the present application, the optical filter group is composed of multiple optical filters with different center frequencies, wherein the number of the optical filters is consistent with the number of beamforming network channels, and the center frequencies of the optical filters are aligned with the center frequencies of the first optical frequency comb signal and the second optical frequency comb signal.

[0012] Optionally, in one embodiment of the present application, the photodetector group includes multiple photodetectors, and the multiple photodetectors are respectively connected to the filter output ends of the optical filter group to down-convert the optically carried linear frequency modulation wave to baseband to obtain a delayed linear frequency modulation wave component.

[0013] Optionally, in one embodiment of the present application, it further includes: a beam splitter, which is connected to the output end of the light source, and is used to split the continuous light and input the split continuous light into the first optical frequency comb generation module and the second optical frequency comb generation module respectively.

[0014] A second aspect of the present application provides a broadband optically controlled beamforming method based on a dual optical frequency comb, comprising: respectively generating a first optical frequency comb signal with a first repetition frequency and a second optical frequency comb signal with a second repetition frequency using the continuous light; modulating the first optical frequency comb signal with a preset broadband linear frequency modulation wave signal to generate a first modulation signal; coupling the first modulation signal and the second optical frequency comb signal, performing filtering and photoelectric detection to frequency-shift and phase-shift the linear frequency modulation wave signal, and outputting a delayed microwave signal after broadband optically controlled beamforming.

[0015] Optionally, in one embodiment of the present application, before coupling the first modulation signal and the second optical frequency comb signal, it also includes: adding a phase shift to each comb tooth of the second optical frequency comb signal to obtain the phase required by the linear frequency modulation wave signal.

[0016] A third aspect of the present application provides a phased array radar, including: a broadband optically controlled beamforming network based on a dual optical frequency comb as described in the above-mentioned embodiment of the present application.

[0017] The embodiments of this application utilize linear frequency-modulated wave frequency-shifting and phase-shifting in the optical domain, replacing an optical true delay network. This results in a simple multi-channel beamforming network with low system complexity, rapid delay adjustment, and support for broadband phased array applications. This overcomes the issues of large system size and difficult delay control inherent in broadband optical beamforming networks.

[0018] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0020] Figure 1 Schematic diagram of a broadband optically controlled beamforming network based on dual optical frequency combs according to an embodiment of the present application;

[0021] Figure 2 Schematic diagram of a broadband optically controlled beamforming network based on a dual optical frequency comb according to an embodiment of the present application;

[0022] Figure 3Schematic diagram of the optical frequency comb teeth and filter passband according to an embodiment of the present application;

[0023] Figure 4 Schematic diagram of the structure of a multi-channel broadband optical beamforming network based on dual optical frequency combs according to an embodiment of the present application;

[0024] Figure 5 This is a simulation effect diagram provided according to an embodiment of the present application;

[0025] Figure 6 Schematic diagram of radar simulation of a broadband optical beamforming method based on dual optical frequency combs according to an embodiment of the present application;

[0026] Figure 7 The present invention provides a flowchart of a method for providing a broadband optically controlled beamforming network based on a dual optical frequency comb according to an embodiment of the present application. DETAILED DESCRIPTION

[0027] The following describes in detail embodiments of the present application. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0028] The following describes the broadband optical beamforming network, method, and phased array radar based on dual optical frequency combs according to the embodiments of the present application with reference to the accompanying drawings. In response to the problems of large system size and difficulty in delay control in the broadband optical beamforming network in the related art mentioned in the background technology center, the present application provides a broadband optical beamforming network based on dual optical frequency combs. It utilizes the free spectral width difference of the dual optical frequency combs to simultaneously provide frequency shift for multiple linear frequency modulated waves, and then simultaneously shifts the phase of the multiple linear frequency modulated waves to achieve true delay of the multiple linear frequency modulated waves. The delay difference is continuously adjustable and easy to operate. A wide range of delay adjustment can be obtained without the use of long delay lines or other delay methods. At the same time, the network structure is simple, the number of devices required is small, and large-scale expansion can be easily achieved. The delay error is small and the channel consistency is high, which is conducive to accurate beamforming. Thus, the problems of large system size and difficulty in delay control in the broadband optical beamforming network in the related art are solved.

[0029] Specifically, Figure 1 Schematic diagram of a broadband optically controlled beamforming network based on dual optical frequency combs according to an embodiment of the present application.

[0030] like Figure 1 As shown, the broadband optically controlled beamforming network 10 based on dual optical frequency combs includes: a light source 100 , a first optical frequency comb generating module 200 , a second optical frequency comb generating module 300 , an electro-optical modulation module 400 and an output module 500 .

[0031] The light source 100 may be a laser that stably outputs continuous light.

[0032] The first optical frequency comb generation module 200 is configured to generate a first optical frequency comb signal with a first repetition frequency using continuous light.

[0033] The second optical frequency comb generation module 300 is configured to generate a second optical frequency comb signal with a second repetition frequency using continuous light.

[0034] It can be understood that the optical frequency comb generation module can stably generate a flat optical frequency comb with a certain free spectral width. In an embodiment of the present application, two optical frequency comb generation modules are included, which respectively generate a first optical frequency comb signal with a first spectral width (i.e., a first repetition frequency) and a second optical frequency comb signal with a second spectral width (i.e., a second repetition frequency).

[0035] The electro-optical modulation module 400 is used to modulate a linear frequency modulation wave signal with a preset pulse width onto the first optical frequency comb signal to generate a first modulation signal.

[0036] It will be appreciated that in the embodiment of the present application, one input terminal of the electro-optical modulation module 400 is connected to the first optical frequency comb generation module 200 to receive the first optical frequency comb signal, and the other input terminal receives the linear frequency modulation signal. In actual implementation, the connection relationship of the electro-optical modulation module 400 can be adjusted according to actual needs, such as connecting the electro-optical modulation module 400 to the second optical frequency comb generation module 300.

[0037] The output module 500 is used to filter and photoelectrically detect the first modulation signal and the second optical frequency comb signal after coupling, so as to frequency-shift and phase-shift the linear frequency modulation wave signal and output a delayed microwave signal after broadband optical beamforming.

[0038] It can be understood that the continuous light output by the light source generates two optical signals after passing through the first optical frequency comb generation module 200 and the second optical frequency comb generation module 300. One optical frequency comb signal is modulated by a linear frequency modulation wave signal and then output, and then coupled with the other optical frequency comb signal, thereby achieving frequency and phase shifting of the linear frequency modulation wave signal, achieving equivalent delay of the linear frequency modulation wave signal, and then outputting a delayed microwave signal after broadband optically controlled beamforming.

[0039] Furthermore, the first and second optical frequency comb generation modules in this embodiment of the present application generate two optical frequency combs with different repetition frequencies, that is, different frequency spacings between the comb teeth. This difference in repetition frequency is related to the delay difference between adjacent channels required by the beamforming network, which determines the beam pointing direction of the phased array. The repetition frequency of the optical frequency comb is at least twice the highest frequency of the linear frequency modulation signal to prevent aliasing of adjacent comb teeth after modulation.

[0040] Optionally, in one embodiment of the present application, the broadband optically controlled beamforming network 10 based on dual optical frequency combs further includes: a beam splitter connected to the output end of the light source, for splitting the continuous light and inputting the split continuous light into the first optical frequency comb generation module and the second optical frequency comb generation module, respectively.

[0041] It can be understood that in order to input the continuous light into the first optical frequency comb generation module 200 and the second optical frequency comb generation module 300 respectively, the embodiment of the present application can set a beam splitter after the light source 100 to split the continuous light into two beams, and input the two beams of light into the first optical frequency comb generation module 200 and the second optical frequency comb generation module 300 respectively.

[0042] Optionally, in one embodiment of the present application, the broadband optically controlled beamforming network 10 based on dual optical frequency combs further includes: a linear frequency modulation wave source, configured to generate a linear frequency modulation wave signal of a preset pulse width, and input the linear frequency modulation wave signal of the preset pulse width into the electro-optical modulator.

[0043] The embodiment of the present application utilizes a linear frequency modulation wave signal of a preset pulse width to modulate the optical frequency comb signal. Optionally, the embodiment of the present application sets a linear frequency modulation wave source in the network structure to generate the linear frequency modulation wave signal required by the embodiment of the present application.

[0044] It's understandable that the parameters of the chirp generated by the chirp source don't need to change based on the phased array parameters, and the pulse width doesn't change based on the preset delay. The difference in repetition frequency between the two optical frequency combs is adjusted based on the chirp rate, K, of the chirp.

[0045] like Figure 2 As shown, one input end of the electro-optical modulation module is connected to the first optical frequency comb generation module, and the other input end is connected to the linear frequency modulation wave source, so that the first optical frequency comb signal is modulated by the linear frequency modulation wave signal output by the linear frequency modulation wave source.

[0046] Specifically, the linear frequency modulation source is a waveform generator that can generate linear frequency modulation waves. The linear frequency modulation signal is a signal whose frequency changes linearly with time. Its time domain expression is written as s(t)=cos(2πf0t+πKt 2 ), where K is the chirp rate of the linear FM wave. The time domain expression of the delayed linear FM wave is written as:

[0047] s ′ (t)=cos(2πf0(t-Δτ)+πK(t-Δτ) 2 )=cos(2π(f0+Δf)t+Δφ+πKt 2 ) (1)

[0048] Where f0 is the initial frequency of the linear frequency modulation wave, Δf = -KΔτ is an equivalent frequency shift, Δφ = -2πf0Δτ + πKΔτ 2 is an equivalent phase shift. As can be seen from Equation (1), when the frequency and phase shifts of a linear FM wave meet the conditions, the effect is equivalent to delaying the linear FM wave. Therefore, a linear FM wave frequency and phase shifting method is implemented in the optical domain, replacing the optical true delay network and realizing a simple multi-channel beamforming network.

[0049] In a specific embodiment of the present application, two optical frequency combs with different free spectral widths are used, such as Figure 2 As shown, the optical frequency comb generated by optical frequency comb generation module 1 is used to carry a broadband linear frequency modulation signal. For ease of description, it is referred to as the signal comb. The optical frequency comb generated by optical frequency comb generation module 2 is used as a local signal to mix with the signal comb and is referred to as the local comb. Assuming the number of channels in this optically controlled beamforming network is M, the number of teeth in the signal and local combs is also M. The free spectral widths of the signal and local combs differ slightly. The teeth of the local and signal combs are numbered, with the number m increasing from 0 to M-1. The teeth with the same number are designated as the mth group of comb teeth. Assuming the combs numbered m = 0 are frequency-aligned, due to the difference in free spectral width between the signal and local combs, the frequency difference between the comb teeth can be expressed as mΔFSR = m(FSR1 - FSR2), where FSR1 is the free spectral width of the signal comb and FSR2 is the free spectral width of the local comb.

[0050] Optionally, in one embodiment of the present application, the broadband optically controlled beamforming network 10 based on dual optical frequency combs further includes: a phase compensation module, which is connected to the output end of the first optical frequency comb generation module or the second optical frequency comb generation module, and is used to add a phase shift to each comb tooth of the second optical frequency comb signal or the first optical frequency comb signal to obtain the phase required by the linear frequency modulation wave signal.

[0051] exist Figure 2 In the embodiment, the electro-optical modulation module is connected to the first optical frequency comb generation module. In the second optical frequency comb generation module, the embodiment of the present application can set a phase compensation module for performing phase compensation on the second optical frequency comb signal.

[0052] Specifically, based on the above embodiment, the phase compensation module adds a phase shift to each tooth of the local optical comb (i.e., the second optical frequency comb signal). The phase shift applied to the optical comb will be transmitted to the linear frequency modulation signal of the signal optical comb sideband during photoelectric detection. The phase shift applied by the phase shift module to the optical comb tooth numbered m is:

[0053] Δφ m =2πf0mΔτ+πKm2 Δτ 2 ,m=0,1,..,M-1 (2)

[0054] In the embodiment of the present application, after the linear frequency modulation wave is frequency-shifted and phase-shifted, the effect is equivalent to delaying the linear frequency modulation wave. Therefore, the embodiment of the present application can set the magnitude of the frequency shift amount and the phase shift amount according to the main delay amount achieved.

[0055] Optionally, in one embodiment of the present application, the output module 500 includes: a coupler for coupling the first modulated signal and the second optical frequency comb signal; an optical filter group for filtering the coupled signal; and a photodetector group for photoelectrically detecting the filtered signal.

[0056] like Figure 2 As shown, in a specific embodiment of the present application, the functions of the output module 500 can be implemented by an optical filter group and a photodetector group. Through the optical filter group and the photodetector, a multi-channel delayed microwave signal is output, which can be used to support a multi-channel array antenna and realize the phased array radar function.

[0057] Optionally, in one embodiment of the present application, the optical filter group is composed of multiple optical filters with different center frequencies, wherein the number of optical filters is consistent with the number of beamforming network channels, and the center frequencies of the optical filters are aligned with the center frequencies of the first optical frequency comb signal and the second optical frequency comb signal.

[0058] Optionally, in one embodiment of the present application, the photodetector group includes multiple photodetectors, and the multiple photodetectors are respectively connected to the filter output ends of the optical filter group to down-convert the optical linear frequency modulation wave to baseband to obtain a delayed linear frequency modulation wave component.

[0059] like Figure 2 As shown in the figure, the electro-optical modulation module includes an electro-optical modulator (EOM) for adjusting the linear frequency modulation wave signal of the preset pulse width. Through electro-optical modulation, the linear frequency modulation wave is modulated onto the signal optical comb. Among them, the optical filter bank is a group of filters with the same passband width and the passband center frequency distributed at equal intervals. The number of filters is the same as the number of channels of this beamforming network, that is, M. Figure 3 As shown, teeth of the signal optical comb and the local optical comb with the same sequence number (close in frequency) are grouped together and filtered out by the optical filter bank. The photodetector module contains M photodetectors, connected to the output terminals of the M optical filters in the optical filter bank. They perform photoelectric detection on the optical signal and obtain a down-converted linear frequency modulation signal. The phase shift added to each tooth of the local optical comb is then transferred to the linear frequency modulation signal.

[0060] After the optical comb group output by the optical filter is photoelectrically detected, the initial frequency of the down-converted linear frequency modulation wave signal obtained will increase by the difference in free spectrum width ΔFSR, that is, the initial frequency of the linear frequency modulation wave signal of the mth channel is

[0061] f m =f0+Δf m =f0+mΔFSR, m=0,1,2,…,M-1 (3)

[0062] In order to support the array element spacing of d, the target pointing angle is θ B For a phased array radar, the delay interval between each array element should be Δτ d =dsinθ B / c. As shown in formula (1), the frequency shift of each channel in the optical beamforming network should satisfy Δf m =mKΔτ d = mKdsinθ B / c. Therefore, the difference in the free spectral width ΔFSR between the signal comb and the local comb should satisfy

[0063] ΔFSR=Kdsinθ B / c (4)

[0064] In summary, after passing through the optically controlled beamforming network proposed in this application, the time domain expression of the linear frequency modulation wave output by the mth channel of the optically controlled beamforming network is:

[0065] s m (t)=cos(2πf0(t-mΔτ d )+πK(t-mΔτ d ) 2 ) (5)

[0066] It can be seen that the present application realizes simultaneous multi-channel optically controlled beamforming through frequency shifting and phase shifting. The link structure is simple and does not require delay lines and delay devices, which greatly simplifies the network complexity and also enables the multi-channel delay amount to be programmable and continuously changed.

[0067] The broadband optically controlled beamforming network based on dual optical frequency combs of the present application is described in detail below with reference to the accompanying drawings and specific embodiments.

[0068] like Figure 4 The network structure shown can realize a 16-channel optical beamforming network and support a 16-element phased array radar transmitter. The specific structure is described as follows:

[0069] An arbitrary waveform generator (AWG) generates a linear frequency modulation signal of 8 to 12 GHz with a time width of 20 μs and a chirp rate of K = 2 × 10 14The array element spacing of the phased array antenna array supported by this beamforming network is d = λ 12GHz / 2=1.25cm, the target beam pointing angle is θ B =60°. A 1550nm laser is used as the light source. A comb frequency interval of ω is generated by cascading a phase modulator and an intensity modulator. RF1 and ω RF2 The electro-optic frequency comb, where ω RF1 =30GHz,ω RF1 -ω RF2 =7.22kHz, which is the frequency of the two single-frequency microwave signals generated by the microwave signal source, and injected into the two optical frequency comb generation modules respectively.

[0070] After the signal comb is generated, it is injected into a dual parallel Mach-Zehnder modulator (DPMZM), which performs single-side suppressed carrier modulation on each comb. After the local comb is generated, a wave shaper is used to phase shift each comb individually, with the phase shift amount satisfying:

[0071] Δφ m =2πf0mΔτ+πKm 2 Δτ 2 ,m=0,1,..,M-1

[0072] Among them, the delay difference between adjacent channels Δτ=dsinθ B / c≈20.8ps, the initial frequency of the linear frequency modulation wave f0=8GHz.

[0073] Based on this, the embodiment of the present application obtains the following by simulating and calculating the signals received at different azimuth angles in the radiation far field: Figure 5 The results, where Figure 5 (1)-(4) are the received signals when the far-field azimuth angles are 60°, 45°, 30°, and 0° respectively: at the designed 60° target direction (such as Figure 5 (1)), we can receive the same linear FM wave signal as the transmitted signal. Although there is distortion at the edge of the window, the distortion is almost negligible due to the wide time width of the linear FM wave. At 45°, 30°, and 0°, which are not the design target directions, Figure 5 (2)- Figure 5 As shown in (4), the correct linear frequency modulation signal cannot be received.

[0074] like Figure 6The figure shows a receiver capable of implementing a 16-element wideband phased array radar. Its basic operating principle is to split the laser light generated by a narrow-linewidth laser into two, each generating two optical combs with unequal repetition frequencies: the upper branch is the signal comb, and the lower branch is the local comb. The received signals from each phased array radar element are modulated onto an optical comb using suppressed carrier single-side modulation. These signals are then combined into a single optical comb carrying the signal through a wavelength division multiplexer. The signal comb and the local comb are coupled into one optical signal. Comb teeth with the same sequence number (close frequency) in the signal and local combs are grouped and filtered out in groups through wavelength division multiplexing. Each group of combs beats frequency to produce a delay-compensated received linear frequency modulation signal. The output linear frequency modulation signals from each group are time-aligned and coherently superimposed. Finally, they are combined and fed into a backend data processing unit for phased array radar reception.

[0075] The broadband optical beamforming network based on dual optical frequency combs proposed in this application utilizes linear frequency modulation (LFM) frequency and phase shifting in the optical domain, replacing an optical true delay network. This results in a simple multi-channel beamforming network with low system complexity, rapid delay adjustment, and support for broadband phased array applications. This overcomes the issues of large system size and difficult delay control inherent in broadband optical beamforming networks.

[0076] Next, a broadband optically controlled beamforming method based on a dual optical frequency comb proposed in accordance with an embodiment of the present application will be described with reference to the accompanying drawings.

[0077] Figure 7 The present invention provides a flowchart of a method for providing a broadband optically controlled beamforming network based on a dual optical frequency comb according to an embodiment of the present application.

[0078] like Figure 7 As shown, the broadband optically controlled beamforming method based on dual optical frequency combs includes the following steps:

[0079] In step S101 , a first optical frequency comb signal with a first repetition frequency and a second optical frequency comb signal with a second repetition frequency are generated using continuous light.

[0080] In step S102, a first optical frequency comb signal carrying a preset broadband linear frequency modulation wave signal is modulated to generate a first modulated signal.

[0081] In step S103, the first modulation signal and the second optical frequency comb signal are coupled and then filtered and photoelectrically detected to perform frequency and phase shifting on the linear frequency modulation signal, and output a delayed microwave signal after broadband optical beamforming.

[0082] Optionally, in one embodiment of the present application, before coupling the first modulation signal and the second optical frequency comb signal, the method further includes: adding a phase shift to each comb tooth of the second optical frequency comb signal to obtain the phase required by the linear frequency modulation wave signal.

[0083] It should be noted that the aforementioned explanation of the embodiment of the broadband optically controlled beamforming network based on dual optical frequency combs is also applicable to the broadband optically controlled beamforming method based on dual optical frequency combs in this embodiment, and will not be repeated here.

[0084] The broadband optical beamforming method based on dual optical frequency combs proposed in this application utilizes linear frequency modulation (LFM) frequency and phase shifting in the optical domain, replacing an optical true delay network. This method implements a simple multi-channel beamforming network with low system complexity, rapid delay adjustment, and support for broadband phased array applications. This overcomes the issues of large system size and difficult delay control inherent in broadband optical beamforming networks.

[0085] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0086] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this application, "N" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0087] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or more executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may be performed out of the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present application belong.

[0088] It should be understood that various parts of the present application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiment, the N steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used to implement: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0089] Those skilled in the art will understand that all or part of the steps in the method of the above embodiment can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiment.

Claims

1. A broadband optically controlled beamforming network based on dual optical frequency combs, characterized in that: include: a light source for outputting continuous light; a first optical frequency comb generating module, configured to generate a first optical frequency comb signal of a first repetition frequency using the continuous light; a second optical frequency comb generating module, configured to generate a second optical frequency comb signal with a second repetition frequency using the continuous light; an electro-optical modulation module, configured to modulate a linear frequency modulation wave signal of a preset pulse width onto the first optical frequency comb signal to generate a first modulation signal; An output module is used to filter and photoelectrically detect the first modulated signal and the second optical frequency comb signal after coupling, so as to frequency-shift and phase-shift the linear frequency modulation wave signal and output a delayed microwave signal after broadband optically controlled beamforming.

2. The broadband optically controlled beamforming network based on dual optical frequency combs according to claim 1, characterized in that: Also includes: The linear frequency modulation wave source is used to generate the linear frequency modulation wave signal of the preset pulse width, and input the linear frequency modulation wave signal of the preset pulse width into the electro-optical modulation module.

3. The broadband optically controlled beamforming network based on dual optical frequency combs according to claim 1, characterized in that: Also includes: A phase compensation module is connected to the output end of the second optical frequency comb generation module and is used to add a phase shift to each comb tooth of the second optical frequency comb signal to obtain the phase required by the linear frequency modulation wave signal.

4. The broadband optically controlled beamforming network based on dual optical frequency combs according to claim 1, characterized in that: The output module includes: a coupler, configured to couple the first modulated signal and the second optical frequency comb signal; an optical filter group, used for filtering the coupled signal; The photoelectric detector group is used for photoelectric detection of the filtered signal.

5. The broadband optically controlled beamforming network based on dual optical frequency combs according to claim 4, characterized in that: The optical filter group is composed of multiple optical filters with different center frequencies, wherein the number of the optical filters is consistent with the number of beamforming network channels, and the center frequencies of the optical filters are aligned with the center frequencies of the first optical frequency comb signal and the second optical frequency comb signal.

6. The broadband optically controlled beamforming network based on dual optical frequency combs according to claim 5, characterized in that: The photoelectric detector group includes multiple photoelectric detectors, which are respectively connected to the filter output ends of the optical filter group to down-convert the optical linear frequency modulation wave to baseband to obtain a delayed linear frequency modulation wave component.

7. The broadband optically controlled beamforming network based on dual optical frequency combs according to claim 1, characterized in that: Also includes: A beam splitter is connected to the output end of the light source, and is used to split the continuous light and input the split continuous light into the first optical frequency comb generation module and the second optical frequency comb generation module respectively.

8. A broadband optical beamforming method based on dual optical frequency combs, characterized in that: Utilizing the broadband optically controlled beamforming network based on dual optical frequency combs according to any one of claims 1 to 7, wherein the method comprises the following steps: generating a first optical frequency comb signal with a first repetition frequency and a second optical frequency comb signal with a second repetition frequency by using the continuous light respectively; Modulating the first optical frequency comb signal carrying a preset broadband linear frequency modulation wave signal to generate a first modulated signal; The first modulated signal and the second optical frequency comb signal are coupled and then filtered and photoelectrically detected to perform frequency and phase shifting on the linear frequency modulation wave signal, thereby outputting a delayed microwave signal after broadband optically controlled beamforming.

9. The method according to claim 8, characterized in that Before coupling the first modulated signal and the second optical frequency comb signal, the method further includes: A phase shift is added to each comb tooth of the second optical frequency comb signal to obtain a phase required by the linear frequency modulation wave signal.

10. A phased array radar, characterized in that: include: A broadband optically controlled beamforming network based on a dual optical frequency comb as described in any one of claims 1 to 7.

Images