Scalable light controlled transmit array architecture

Abstract

The application provides an extensible optical control transmitting array architecture, and relates to the field of phased array technology.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 to generate an optical signal;the electro-optical 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 plurality of splicable and parallel arranged dispersion delay channels, each dispersion delay channel generates a time delay through a dispersion optical fiber and the delay length is the same, so that the time delay of each channel output signal is the sum of the delay length of all the channels arranged in advance and the delay length of the channel;after all the optical delay signals pass through the photoelectric detectors, they are radiated to space through the antenna array to form a transmitting beam in the far field by superposition.The delay length can be adjusted by changing the wavelength of the light, and the number of channels can be flexibly increased or decreased through an expansion interface according to the requirement, so as to realize the flexible expansion of the array scale.

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 relatively mainstream technology in the field of radar technology. This technology forms a radar detection beam by controlling the phase of the array microwave signal and quickly adjusts the scanning angle of the detection beam, realizing rapid scanning and flexible scheduling of the radar detection beam in the airspace, solving the problems of slow scanning speed and poor detection beam flexibility of traditional mechanical radar antennas.

[0003] However, as the radar signal bandwidth increases, the phased array system will be affected by the effects of dispersion delay and aperture, 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] Optically controlled array transmit beam scanning technology combines optical and microwave technologies. A microwave signal is loaded onto an optical signal via an electro-optical modulator, converting the microwave signal's phase information into the optical signal's true delay information. The microwave signal's phase information is adjusted by precisely controlling the optical signal's delay, and the delay is flexibly altered by adjusting the optical wavelength. Because the optical signal frequency is many orders of magnitude higher than that of the microwave signal, the effect of microwave frequency changes on the optical signal's delay is negligible. The beam's pointing direction remains unchanged with changes in microwave signal frequency. The system maintains precise beam pointing at any frequency within the broadband signal range, and beam quality does not degrade with increasing frequency. Therefore, microwave photonic arrays are capable of effectively transmitting ultra-wideband signals.

[0005] Current optical array technology primarily uses single-mode optical fiber to transmit microwave signals, varying the optical signal's delay by changing the fiber's length. This method requires the preparation of a large number of optical fibers, each with its own precise length. Once the number and length of all fibers are determined, the corresponding beam direction and array size are also determined. Summary of the Invention

[0006] (1) Technical problems solved

[0007] In view of the shortcomings of the existing technology, 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] (2) 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-optical modulator is used to add a microwave signal to 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 optical 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 modular 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 portion 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 magnitude of the other 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 dispersion optical fiber.

[0024] (3) Beneficial effects

[0025] The present invention provides a scalable light-controlled emission array architecture. Compared with the prior art, it has the following advantages:

[0026] In the present invention, a light source is used to generate an optical signal; an electro-optical modulator is used to load a microwave signal onto the optical signal to generate a modulated signal; an optical delay network is composed of a number of dispersive delay channels that can be spliced ​​and arranged in parallel, each dispersive delay channel having the same delay length, 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; and an array antenna is used to radiate the photocurrents of all branches into space through the antenna array, so that they are superimposed in the far field to form a transmission beam. Because the optical delay network is formed by the rapid splicing of multiple dispersive delay channels, it can be expanded at the unit level and component level 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 following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 any creative work.

[0028] Figure 1 A schematic structural diagram 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] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort 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 a scalable 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 with reference to 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, which is characterized by including 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-optical modulator is used to add a microwave signal to 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 optical 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 multiple 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 embodiment 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 portion 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 magnitude of the other 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 the 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 changed by the change of the microwave wavelength.

[0049] For example, refer to Figure 1 Assuming that the optical delay network includes N dispersive delay channels and the number of corresponding photodetectors is also N, the working principle of the scalable optically controlled emission array architecture can be summarized as follows:

[0050] A tunable laser generates an optical signal. An electro-optical modulator loads the microwave signal to be transmitted onto the optical signal. The optical carrier signal (modulation signal) passes through optical delay channel 1 and is then split into two optical delay signals. One signal enters photodetector 1, and the other enters optical delay channel 2. The optical carrier signal (optical delay signal) passes through optical delay channel 2 and is further split into two optical delay signals. One signal enters photodetector 2, and the other enters optical delay channel 3. This continues in this manner until the optical carrier signal enters the Nth delay channel and the Nth photodetector. These N photodetectors convert the optical delay signals into photocurrents and send them to the array antenna.

[0051] Each dispersion-delay channel consists of an optical power splitter, a dispersion-delay fiber, and an optical attenuator. Its external interfaces include an optical input port, an optical output port, and an expansion port. Dispersion-delay channels are connected via the expansion port and the optical signal input port. The optical signal enters the dispersion-delay fiber through the optical input port, with a fixed delay length. After entering the optical splitter, the delayed optical signal is split into two paths. One path passes through the optical attenuator, exits the optical output port, and is fed into a photodetector. The other path is output through the expansion port and enters the optical input port of the next dispersion-delay channel. This continues in this order, with the optical signal sequentially entering all dispersion-delay channels of the optical delay network.

[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 in the figure, after entering the dispersive delay channel, an optical signal (assuming wavelength λ, center wavelength λ0, and wavelength difference Δλ = λ - λ0) first passes through a dispersive fiber with a delay length of Δl (dispersion coefficient D) and then splits into two paths. One path enters photodetector 1 and is converted into an electrical signal I1(Δl). This signal has a delay of Δl, while the other path enters dispersive delay channel 2. After entering delay channel 2, the optical signal again passes through a dispersive fiber with a fixed length of Δl and then splits into two paths. One path enters photodetector 2 and is converted into an electrical signal I2(2Δl). This signal has a delay of 2Δl, which is the sum of the delay lengths of delay channel 1 and delay channel 2. The other path enters dispersive delay channel 3. After entering delay channel 3, the optical signal passes through a dispersion optical fiber with a fixed length of Δl in the same way and is then split into two paths. One path enters photodetector 3 and is converted into an electrical signal I3(3Δl). The delay of this path is 3Δl, which is the sum of the delay lengths of delay channels 1, 2, and 3. The other path enters dispersion delay channel 4. Similarly, it enters 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 of each branch of the delay structure is the same. The microwave signals radiated from each branch through the antenna array element are superimposed with equal phases at the infinite distance of the antenna array, and the synthetic transmission beam points to 0° in azimuth.

[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). As a result, the main beam of the demodulated microwave signal will be deflected in the counterclockwise direction. 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 be deflected in the clockwise direction.

[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 serves as the optical input port of the optical delay network, the expansion port of dispersion delay channel N serves as the expansion port of the optical delay network, and the optical output ports of dispersion delay channels 1, 2, 3, ..., N serve 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 port of dispersion delay channel N is connected to the optical input port of dispersion delay channel N+1 to achieve channel expansion. Amplitude balancing between channels is achieved by adjusting the optical attenuator.

[0057] A more accurate understanding is that, in fact, the dispersion delay channels provided by the embodiments of the present invention can be spliced ​​through standardized interfaces to form an optical delay network and achieve 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, with the fiber length within the module uniformly calibrated in advance. The module features an optical input port, an optical output port, and an expansion interface. The optical input port of an expansion channel is directly connected to the expansion interface of the existing channel to quickly expand a single channel. Expansion of multiple channels is similar to expanding a single channel, connecting the channels together using the same interface connection method.

[0059] Component-level expansion uses multiple channels as a standard functional module. The fiber lengths of each channel within the module are pre-matched, with a uniform length difference. The module features an optical input port, multiple delayed output ports, and an expansion interface. The optical input port of the expansion module connects directly to the expansion interface of the original module to quickly expand a component. Expanding multiple components is similar to expanding a single component, connecting the channels together through the same interface connection method, allowing for rapid channel addition.

[0060] Furthermore, in order to better understand the embodiments of the present invention, combined with the working principle introduced above, Figure 1 Taking the scalable optical 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] Where ω0 is the angular frequency of the optical signal, E0 is the amplitude of the optical signal, and t is 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] After the microwave signal is modulated by the electro-optical modulator, it is loaded onto the optical signal, generating a modulated signal expressed as:

[0069]

[0070] Where, 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 into Bessel functions while ignoring higher-order terms yields:

[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 split through the optical delay network to form multiple optical delay signals.

[0077] The optical delay network consists of multiple single-path dispersive delay channels, each with a fixed delay length of Δl. Ultimately, the optical signal enters each of N delay channels, generating N delayed signals that enter the photodetector. The delays of these N delayed signals are Δl, 2Δl, …, NΔl, in sequence.

[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] Where 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 separation 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. After filtering out the DC term and high-frequency components in the photocurrent, the photocurrent component containing the microwave signal can be expressed as:

[0085] I∝2ηJ0J1cos(ω RF t+ω RF hΔt)

[0086] Where 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 the signals from each antenna unit in the far field direction is as follows:

[0088]

[0089] Among them, θ is the direction of the transmitted beam, λ is the wavelength corresponding to the angular frequency of the microwave signal, d is the spacing between antenna elements, and Δφ is the wavelength of the microwave signal. h is the phase delay of the h-th 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 caused by the dispersive fiber of adjacent dispersion 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 is changed, thereby achieving flexible control of the beam pointing angle.

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

[0098] 1. Wider working bandwidth: Using dispersive optical fiber 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 affected by changes in the microwave wavelength.

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

[0100] 3. Flexible expansion of the size of the optical control array: The general and modular optical delay channels are used, and the external interface, internal structure and delay length of each delay channel are completely the same. A large number of delay channels can be prepared in advance, and the optical delay network can be quickly spliced and combined by connecting the channels through the 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 text, relational terms such as first and second are used only to distinguish one entity or operation from another, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment. Without more limitations, the element defined by the statement "including a" does not exclude the presence of other identical elements in the process, method, article or equipment including the element.

[0102] The above embodiments are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A scalable optical 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; The light source is used to generate a light signal; The electro-optical modulator is used to add a microwave signal to 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 optical 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 superimpose in the far field to form a transmission beam; 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 portion 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 magnitude of the other 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.

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

3. The scalable optical emission array architecture according to claim 1, wherein: The delay element is a dispersion optical fiber.

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