Scalable light-operated emission array architecture

Abstract

The invention provides an extensible light-operated emission array architecture, and relates to the technical field of phased arrays. The architecture comprises a light source, an electro-optical modulator, an optical delay network, a plurality of photoelectric detectors and an array antenna. The light source can adopt a wavelength tunable laser for generating an optical signal; the electro-optical modulator is used for loading the microwave signal onto the optical signal to generate a modulation signal; the optical delay network is composed of a plurality of dispersion delay channels which can be spliced and arranged in parallel, each dispersion delay channel generates time delay through a dispersion optical fiber and has the same delay length, so that the output signal delay amount of each channel is the sum of the delay length of all channels arranged in advance and the delay length of the channel; and after passing through the photoelectric detector, all the optical delay signals are radiated to the space through the antenna array so as to be superposed in a far field to form a transmitting wave beam. The delay length can be adjusted by changing the optical wavelength, and the number of channels can be flexibly increased or decreased through the expansion interface according to needs, so that the flexible expansion of the array scale is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of phased arrays, and in particular to an expandable light-controlled emission array architecture. Background Art

[0002] Phased array technology is a mainstream technology in the field of radar technology. This technology forms a radar detection beam through phase control of the array microwave signal and quickly adjusts the scanning angle of the detection beam, thereby realizing rapid scanning and flexible scheduling of the radar detection beam in the airspace, solving the problems of slow scanning speed and poor flexibility of the detection beam of traditional mechanical radar antennas.

[0003] However, as the radar signal bandwidth increases, the phased array system will be affected by the dispersion delay and aperture effect, resulting in a decrease in the target pointing accuracy of the detection beam, thereby reducing the echo energy of the detected target and affecting the detection effect of the system.

[0004] The optically controlled array transmission beam scanning technology combines optical technology with microwave technology. The microwave signal is loaded onto the optical signal through an electro-optical modulator, and the phase information of the microwave signal is converted into the true delay information of the optical signal. The phase information of the microwave signal is adjusted by precisely controlling the delay of the optical signal, and the delay is flexibly changed by adjusting the optical wavelength. Since the frequency of the optical signal is many orders of magnitude higher than that of the microwave signal, the effect of the microwave frequency change on the optical signal delay can be ignored. The direction of the beam will not deviate with the change of the microwave signal frequency. For any frequency point within the broadband signal range, the system can maintain accurate beam pointing, and the beam quality will not decrease with the increase of frequency. Therefore, the microwave photon array can effectively realize the transmission of ultra-wideband signals.

[0005] The current optical control array technology mainly uses single-mode optical fiber to transmit microwave signals, and changes the delay of optical signals by changing the length of the optical fiber. This method requires a large number of optical fibers to be prepared in advance, and the length of each optical fiber needs to be accurately matched in advance. Once the number and length of all optical fibers are determined, the corresponding beam direction and array size are also determined. Summary of the invention

[0006] 1. Technical issues to be resolved

[0007] In view of the deficiencies of the prior art, the present invention provides an expandable light-controlled emission array architecture, which solves the technical problem that the array scale cannot be flexibly expanded.

[0008] (II) Technical solution

[0009] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0010] A scalable optically controlled emission array architecture includes a light source, an electro-optical modulator, an optical delay network, a plurality of photodetectors, and an array antenna;

[0011] The light source is used to generate a light signal;

[0012] The electro-optic modulator is used to load the microwave signal onto the optical signal to generate a modulated signal;

[0013] The optical delay network is composed of a plurality of dispersive delay channels that can be spliced ​​and arranged in parallel, and the delay length of each of the dispersive delay channels is the same, so that the modulated signal forms optical delay signals of different branches;

[0014] Each of the photodetectors is used to convert the light delay signal of the corresponding branch into a photocurrent;

[0015] The array antenna is used to radiate the photocurrents of all branches toward space through the antenna array, so as to be superimposed in the far field to form a transmission beam.

[0016] Preferably, the light source is a wavelength tunable laser.

[0017] Preferably, any of the dispersion delay channels adopts a standardized building block design architecture, including an optical input port, a delay element, an optical splitter, an expansion interface, an optical attenuator, and an optical output port;

[0018] One end of the delay element is connected to the optical input port, and the other end is connected to the optical splitter, and is used to provide a fixed delay length to generate an optical delay signal;

[0019] The optical splitter separates the expansion interface and the optical output port, and is used to divide the optical delay signal into two parts;

[0020] The extension interface is connected to the optical input port of the next dispersion delay channel, and is used to output a part of the optical delay signal;

[0021] The optical attenuator is located between the optical splitter and the optical output port, and is used to adjust the size of another part of the optical delay signal;

[0022] The optical output port is connected to the corresponding photoelectric detector and is used to output the optical delay signal after the size adjustment as the optical delay signal of the branch.

[0023] Preferably, the delay element is a dispersive optical fiber.

[0024] (III) Beneficial effects

[0025] The present invention provides an expandable light-controlled emission array architecture. Compared with the prior art, it has the following beneficial effects:

[0026] In the present invention: the light source is used to generate an optical signal; the electro-optic modulator is used to load a microwave signal onto the optical signal to generate a modulated signal; the optical delay network is composed of a number of dispersive delay channels that can be spliced ​​and arranged in parallel, and the delay length of each dispersive delay channel is the same, so that the modulated signal forms optical delay signals of different branches; each photodetector is used to convert the optical delay signal of the corresponding branch into a photocurrent; the array antenna is used to radiate the photocurrents of all branches into space through the antenna array, so as to form a transmission beam by superposition in the far field. Since the optical delay network is formed by the rapid splicing of multiple dispersive delay channels, unit-level expansion and component-level expansion can be achieved by increasing the number of channels, thereby achieving flexible expansion of the array scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 A schematic diagram of the structure of an expandable light-controlled emission array architecture provided by an embodiment of the present invention;

[0029] Figure 2 A schematic diagram of a dispersion delay channel provided by an embodiment of the present invention;

[0030] Figure 3 A schematic diagram of an optical delay network optical path provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] The embodiments of the present application solve the technical problem that the array scale cannot be flexibly expanded by providing an expandable light-controlled emission array architecture.

[0033] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0034] like Figure 1As shown, an embodiment of the present invention provides a scalable optically controlled emission array architecture, characterized in that it includes a light source, an electro-optical modulator, an optical delay network, a plurality of photodetectors and an array antenna.

[0035] The light source is used to generate a light signal;

[0036] The electro-optic modulator is used to load the microwave signal onto the optical signal to generate a modulated signal;

[0037] The optical delay network is composed of a plurality of dispersive delay channels that can be spliced ​​and arranged in parallel, and the delay length of each of the dispersive delay channels is the same, so that the modulated signal forms optical delay signals of different branches;

[0038] Each of the photodetectors is used to convert the light delay signal of the corresponding branch into a photocurrent;

[0039] The array antenna is used to radiate the photocurrents of all branches toward space through the antenna array, so as to be superimposed in the far field to form a transmission beam.

[0040] In the embodiment of the present invention, since the optical delay network is formed by rapidly splicing a plurality of dispersion delay channels, unit-level expansion and component-level expansion can be achieved by increasing the number of channels, thereby achieving flexible expansion of the array scale.

[0041] In an optional embodiment, if Figure 1 As shown, in the embodiment of the present invention, the light source adopts a wavelength tunable laser, and the phase between each antenna unit is changed by adjusting the wavelength of light, thereby realizing flexible control of any pointing angle of the beam.

[0042] In an optional embodiment, if Figure 2 As shown, in the embodiments of the present invention, any of the dispersion delay channels adopts a standardized building block design architecture, including an optical input port, a delay element, an optical splitter, an expansion interface, an optical attenuator, and an optical output port.

[0043] One end of the delay element is connected to the optical input port, and the other end is connected to the optical splitter, and is used to provide a fixed delay length to generate an optical delay signal;

[0044] The optical splitter separates the expansion interface and the optical output port, and is used to divide the optical delay signal into two parts;

[0045] The extension interface is connected to the optical input port of the next dispersion delay channel, and is used to output a part of the optical delay signal;

[0046] The optical attenuator is located between the optical splitter and the optical output port, and is used to adjust the size of another part of the optical delay signal;

[0047] The optical output port is connected to the corresponding photoelectric detector and is used to output the optical delay signal after the size adjustment as the optical delay signal of the branch.

[0048] In an optional embodiment, if Figure 2 As shown, the embodiment of the present invention uses dispersive optical fiber as a delay element. Since the delay length is determined by the length of the optical fiber itself and has nothing to do with the wavelength of the microwave signal, the beam pointing is not affected by changes in the microwave wavelength.

[0049] For example, refer to Figure 1 In the setting, the optical delay network includes N dispersive delay channels, and the number of corresponding photodetectors is also N. Then the working principle of the scalable optical control emission array architecture provided can be summarized as follows:

[0050] The tunable laser generates an optical signal, and the electro-optic modulator loads the microwave signal to be transmitted onto the optical signal. The optical carrier signal (modulation signal) passes through the optical delay channel 1 and is split into two optical delay signals, one of which enters the photodetector 1 and the other enters the optical delay channel 2. The optical carrier signal (optical delay signal) passes through the optical delay channel 2 and is further split into two optical delay signals, one of which enters the photodetector 2 and the other enters the optical delay channel 3. By analogy, the optical carrier signal enters the Nth delay channel and the Nth photodetector. The N photodetectors convert the optical delay signals into photocurrents and send them to the array antenna.

[0051] Each dispersion delay channel includes an optical power splitter, a dispersion delay fiber and an optical attenuator, and the external interface includes an optical input port, an optical output port and an extension port. The dispersion delay channels are connected through the extension port and the optical signal input port. The optical signal enters the dispersion delay fiber through the optical input port, and the delay length is fixed. After entering the optical splitter, the delayed optical signal is divided into two paths. One path is output from the optical output port after passing through the optical attenuator and sent to the photodetector, and the other path is output through the extension port and enters the optical input port of the next dispersion delay channel. By analogy, the optical signal enters all the dispersion delay channels of the optical delay network in turn.

[0052] According to the internal structure of the dispersion delay channel and the optical control transmission array architecture, the delay method of the optical signal, such as Figure 3As shown. After entering the dispersion delay channel, the optical signal (assuming wavelength λ, center wavelength λ0, wavelength difference Δλ=λ-λ0) first passes through the dispersion optical fiber (dispersion coefficient D) with a delay length of Δl and then is divided into two paths. One path enters the photodetector 1 and is converted into an electrical signal I1 (Δl). The delay of this signal is Δl, and the other path enters the dispersion delay channel 2. After entering the delay channel 2, the optical signal passes through the dispersion optical fiber with a fixed length of Δl again and is then divided into two paths. One path enters the photodetector 2 and is converted into an electrical signal I2 (2Δl). The delay of this signal is 2Δl, which is the sum of the delay lengths of delay channel 1 and delay channel 2. The other path enters the dispersion delay channel 3. After the optical signal enters the delay channel 3, it passes through the dispersion optical fiber with a fixed length of Δl in the same way and then splits into two paths. One path enters the photodetector 3 and is converted into an electrical signal I3 (3Δl). The delay amount of this path is 3Δl, which is the sum of the delay lengths of delay channels 1, 2 and 3. The other path enters the dispersion delay channel 4. In this way, it enters the delay channel N to form an electrical signal I N (NΔl), the delay amount is NΔl. In summary, the delay length difference between each delayed signal is Δl, and the corresponding delay difference is DΔlΔλ.

[0053] Adjust the output wavelength of the tunable laser. For the central wavelength λ0, the delay amounts of each branch of the delay structure are the same. The microwave signals radiated from each branch through the antenna array element are superimposed with equal phases at an infinite distance from the antenna array, and a transmission beam pointing to 0° is synthesized.

[0054] When the wavelength of the optical carrier is less than λ0, the delay of each branch increases due to the different dispersion of the optical carrier (the delay is proportional to the dispersion), so the main beam of the demodulated microwave signal will deflect counterclockwise. Conversely, when the wavelength of the optical carrier is greater than λ0, the delay of each branch decreases, and the main beam of the microwave signal will deflect clockwise.

[0055] Furthermore, it is understandable that the embodiments of the present invention provide optical delay network support for flexible expansion.

[0056] Specifically, the optical input port of dispersion delay channel 1 is used as the optical input port of the optical delay network, the expansion interface of dispersion delay channel N is used as the expansion interface of the optical delay network, and the optical output ports of dispersion delay channels 1, 2, 3, ..., N are used as the optical output ports of the optical delay network. The optical carrier signal enters the optical delay network through the optical input port and is output through the N optical output ports. When channel expansion is required, the expansion interface of dispersion delay channel N is connected to the optical input port of dispersion delay channel N+1 to be expanded, so as to achieve the expansion of the dispersion delay channel. The amplitude balance between channels is achieved by adjusting the optical attenuator.

[0057] A more accurate understanding is that, in fact, the dispersion delay channel provided by the embodiment of the present invention can be spliced ​​through standardized interfaces to form an optical delay network and realize the expansion of the optical delay network (including unit-level expansion and component-level expansion); wherein:

[0058] Unit-level expansion uses a dispersion delay channel as a standard functional module, and the fiber length in the module is uniformly calibrated in advance. The module has an optical input port, an optical output port and an expansion interface. The optical input port of the expansion channel is directly connected to the expansion interface of the original channel to quickly expand a channel. The expansion of multiple channels is the same as that of a single channel. The channels can be connected to each other through the same interface connection method to achieve the expansion of multiple channels.

[0059] Component-level expansion uses multiple channels as a standard functional module. The optical fiber lengths of each channel in the module are matched in advance and have a uniform length difference. The module has an optical input port, multiple delayed output ports and an expansion interface. The optical input port of the expansion module is directly connected to the expansion interface of the original module to quickly expand a component. The expansion of multiple components is the same as that of a single component. The channels can be connected to each other through the same interface connection method to achieve the expansion of multiple components and quickly increase the number of channels.

[0060] Further, in order to better understand the embodiments of the present invention, combined with the working principle introduced above, Figure 1 Taking the scalable optically controlled emission array shown in the figure as an example, the following detailed signal flow description is provided:

[0061] The light source uses a wavelength tunable laser to generate an optical signal, and the microwave signal is loaded onto the optical signal through electro-optical modulation.

[0062] The optical signal output by the frequency modulated continuous wave laser is expressed as:

[0063] E in (t)=E0 cosω0t

[0064] Wherein, ω0 is the angular frequency of the optical signal, E0 is the amplitude of the optical signal, and t is the time.

[0065] The microwave signal is expressed as:

[0066] V RF (t) = V RF cosω RF t

[0067] Where V RF is the amplitude of the microwave signal, ω RF is the angular frequency of the microwave signal.

[0068] When the microwave signal is modulated by the electro-optic modulator, the microwave signal is loaded onto the optical signal, and the generated modulated signal is expressed as:

[0069]

[0070] In the formula, It represents the phase change caused by electro-optical modulation, M is the modulation signal identifier, and m is the modulation coefficient.

[0071] Through the change of trigonometric function, the above formula can be expressed as:

[0072]

[0073] Expanding the above equation by Bessel function while ignoring the higher-order terms, we can get:

[0074]

[0075] Wherein, J0 is the 0th order Bessel function, J1 is the 1st order Bessel function, and i is the imaginary unit.

[0076] The modulated signal is divided into multiple optical delay signals through an optical delay network.

[0077] The optical delay network is composed of multiple single-channel dispersion delay channels, and the delay length of each channel is fixed Δl. Finally, the optical signal enters N delay channels and generates N delayed signals entering the photoelectric detector, and the delay amounts of the N delayed signals are Δl, 2Δl, ..., NΔl respectively.

[0078] The formula for the optical delay signal of the hth (h=1,2,…,N) channel is as follows:

[0079]

[0080] Among them, ω0hΔt is the phase change caused by time delay; hΔt is the time delay corresponding to the channel delay length.

[0081] Since the dispersion delay channel uses dispersion compensating optical fiber as a delay element, the time delay correspondence is as follows:

[0082] Δt=DΔlΔλ

[0083] Wherein, D is the dispersion coefficient of the dispersive fiber, in ps / nm / km; Δl is the delay length of the dispersive fiber, in km; Δλ is the spectral interval between the wavelength λ of the optical carrier signal generated by the tunable laser and the central wavelength λ0, in nm.

[0084] After the optical delay signal of the hth channel passes through the photodetector, the optical power is converted into photocurrent, and the DC term and high-frequency component in the photocurrent are filtered out. The photocurrent component containing the microwave signal can be expressed as:

[0085] I∝2ηJ0J1cos(ω RF t+ω RF hΔt)

[0086] Wherein, η is the photoelectric conversion efficiency.

[0087] The photocurrent output by each branch is radiated into space through the antenna array and superimposed in the far field to form a transmission beam. The superimposed field strength of each antenna unit signal in the far field direction is as follows:

[0088]

[0089] Among them, θ is the direction of the transmitting beam, λ is the wavelength corresponding to the angular frequency of the microwave signal, d is the spacing between antenna elements, and Δφ h is the phase delay of the hth optical signal (Δφ h =ω RF hΔt).

[0090] The direction function after summing and normalizing the geometric series is expressed as:

[0091]

[0092] The beam pointing is expressed as:

[0093]

[0094] Where Δφ is the phase difference produced by the dispersive fiber of adjacent dispersive delay channels:

[0095] Δφ=ω RF Δt=ω RF DΔlΔλ

[0096] The phase difference is related to the wavelength of light. By adjusting the wavelength of light, the phase between channels can be changed, thereby achieving flexible control of the beam pointing angle.

[0097] In summary, compared with the prior art, the present invention has the following beneficial effects:

[0098] 1. Larger working bandwidth: Dispersive optical fiber is used as the delay element. The delay length is determined by the length of the optical fiber itself and has nothing to do with the wavelength of the microwave signal. The beam pointing is not changed by the change of the microwave wavelength.

[0099] 2. More flexible beam pointing: The delay length of dispersive optical fiber is related to the wavelength of the optical carrier signal. By adjusting the wavelength of the optical carrier signal through a tunable laser, the optical fiber delay can be flexibly adjusted, so that the direction of the transmitted beam can be arbitrarily adjusted. The existing optical beam synthesis network uses single-mode optical fiber, the delay is fixed, and the beam pointing cannot be flexibly adjusted.

[0100] 3. The scale of the optical control array can be flexibly expanded: it adopts universal and modular optical delay channels, and the external interface, internal structure and delay amount of each delay channel are exactly the same. A large number of delay channels can be made in advance, and each channel can be quickly spliced ​​and combined into an optical delay network by connecting through an expansion interface. The number of optical delay channels can also be expanded by increasing the number of interfaces through the expansion interface.

[0101] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0102] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A scalable light-controlled emission array architecture, characterized in that: It includes a light source, an electro-optic modulator, an optical delay network, a plurality of photodetectors and an array antenna; The light source is used to generate a light signal; The electro-optic modulator is used to load the microwave signal onto the optical signal to generate a modulated signal; The optical delay network is composed of a plurality of dispersive delay channels that can be spliced ​​and arranged in parallel, and the delay length of each of the dispersive delay channels is the same, so that the modulated signal forms optical delay signals of different branches; Each of the photodetectors is used to convert the light delay signal of the corresponding branch into a photocurrent; The array antenna is used to radiate the photocurrents of all branches toward space through the antenna array, so as to be superimposed in the far field to form a transmission beam.

2. The scalable light-controlled emission array architecture according to claim 1, wherein: The light source is a wavelength tunable laser.

3. The scalable light-controlled emission array architecture of claim 1, wherein: Any of the dispersion delay channels adopts a standardized building block design architecture, including an optical input port, a delay element, an optical splitter, an expansion interface, an optical attenuator, and an optical output port; One end of the delay element is connected to the optical input port, and the other end is connected to the optical splitter, and is used to provide a fixed delay length to generate an optical delay signal; The optical splitter separates the expansion interface and the optical output port, and is used to divide the optical delay signal into two parts; The extension interface is connected to the optical input port of the next dispersion delay channel, and is used to output a part of the optical delay signal; The optical attenuator is located between the optical splitter and the optical output port, and is used to adjust the size of another part of the optical delay signal; The optical output port is connected to the corresponding photoelectric detector and is used to output the optical delay signal after the size adjustment as the optical delay signal of the branch.

4. The scalable light-controlled emission array architecture according to claim 3, wherein: The delay element is a dispersion optical fiber.

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