High power tunable optical true time delay phased array transmitter based on light guiding devices
By combining optical waveguide devices and using fiber delay and spatial delay technologies, the problem of limited power capacity of single devices in optical waveguide RF systems has been solved, enabling multi-parameter adjustment and efficient output of high-power microwaves, which is suitable for high-power microwave source applications.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NAT UNIV OF DEFENSE TECH
- Filing Date
- 2023-12-25
- Publication Date
- 2026-05-19
AI Technical Summary
In existing optical waveguide RF systems, the power capacity of single-channel devices is limited, which restricts the maximum output power of a single optical waveguide RF system. Furthermore, traditional true delay technology is bulky, heavy, and slow to adjust, making it difficult to achieve effective output of high-power microwaves.
A high-power tunable optical true delay phased array transmitting system based on optical guide devices is adopted. Combining spatial optical delay and fiber delay technologies, the system achieves efficient laser beam splitting, delay, and synthesis through the combination of signal generator, electro-optic modulator, laser amplification module, optical path adjustment module, spatial optical delay module, optical coupling module, optical guide semiconductor module, and antenna array module. The combination of fiber delay module and spatial delay module improves delay accuracy and speed.
It achieves flexible adjustment of multiple parameters for high-power microwaves, with output power reaching the MW level. It features ultra-wideband, low loss, and strong anti-radiation interference capability, making it suitable for practical applications of high-power microwave sources.
Smart Images
Figure CN117792504B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of high-power microwave technology, and in particular to a high-power tunable optical true-delay phased array transmission system based on photoconductive devices. Background Technology
[0002] High-power microwave sources are widely used in applications such as pulse radar, continuous-wave radar, charged particle radio frequency accelerators, plasma heating, and directed energy systems. Previous research has focused on high-power microwave sources based on electron beam-free solid-state devices, leading to more efficient, miniaturized, and compact systems. In recent years, photoconductive radio frequency technology utilizing linear wide-bandgap photoconductive semiconductors and tunable laser sources has attracted significant attention. Its high-power microwave output offers advantages such as ultra-widebandwidth, low loss, low timing jitter, tunable frequency and pulse width, electromagnetic interference resistance, and small size and weight. The low timing jitter of its output waveform provides a significant advantage in power combining.
[0003] Optical guide semiconductor devices are a key component of narrowband high-power microwave sources. Third-generation semiconductors possess excellent properties such as wide bandgap, high electron saturation drift velocity, high carrier mobility, high critical breakdown field strength, and high thermal conductivity. In recent years, the characteristics and applications of third-generation semiconductors such as SiC and GaN in the field of optical guide radio frequency (RF) have been extensively studied. Currently, the power capacity of single-channel devices in optical guide RF systems is severely limited. The main factors limiting the maximum output power of a single channel in an optical guide RF system are the device's voltage withstand capability and response linearity. This means that the efficiency and linearity of current optical guide devices cannot be simultaneously optimized. Therefore, to realize high-power applications of optical guide microwaves, while continuously increasing the single-channel power capacity to the hundreds of kW level, it is necessary to overcome the technical challenges of array combining to achieve the goal of hundreds of megawatts of microwave output power while maintaining good linear response of each channel device.
[0004] Phased arrays possess excellent beam agility, but during wide-bandwidth angle scanning, transit time and aperture effects limit the instantaneous bandwidth of the signal. Therefore, true delay technology is introduced for delay compensation. Traditional TTDs are constructed from waveguides or coaxial cables, resulting in significant size and weight, which inconveniences both transmission loss and engineering implementation for broadband signals. Optical True Time Delay (OTTD) technology can avoid beam skew, and some of these techniques have already been applied to time-controlled links in microwave photonic power combining.
[0005] Spatial optical delay structures have advantages such as being able to withstand large optical power and continuously adjust the optical path, and they have high stability. The laser signal is almost unaffected by the environment during transmission, enabling high-fidelity and low-jitter transmission. However, they occupy a large space and the adjustment speed is slow when the spatial adjustment delay is large.
[0006] In summary, the present invention aims to provide a high-power microwave system that solves the problem of limited power capacity of single-channel devices, and can achieve high-power microwave output with adjustable macro pulse waveform, pulse cluster repetition frequency, pulse width, and pulse main frequency, wherein the output power of a single-channel photoconductor device can reach the MW level. Summary of the Invention
[0007] To address the aforementioned technical problems, this invention provides a high-power tunable optical true-delay phased array transmission system based on photoconductive devices, comprising a signal generator, a narrowband semiconductor laser, an arbitrary waveform generator, a first electro-optic modulator, a second electro-optic modulator, an optical isolator, a laser amplification module, a multiplexer, an optical path adjustment module, a spatial optical delay module, an optical coupling module, a photoconductive semiconductor module, and an antenna array module.
[0008] The output of the signal generator is connected to the electrical input of the first electro-optic modulator, and the output of the narrowband semiconductor laser is connected to the optical input of the first electro-optic modulator. The output of the first electro-optic modulator is connected to the electrical input of the second electro-optic modulator, and the output of the arbitrary waveform generator is connected to the optical input of the second electro-optic modulator. The output of the second electro-optic modulator is connected to the input of the optical isolator, and the output of the optical isolator is connected to the input of the laser amplification module. The output of the laser amplification module is connected to the input of the multi-channel beam splitter, and the output of the multi-channel beam splitter is connected to the input of the optical path adjustment module. The output of the optical path adjustment module is opposite to the input of the spatial optical delay module. The optical coupling module includes several arrayed optical couplers, and the inputs of the optical couplers are respectively opposite to the outputs of the corresponding spatial optical delay modules. The output of the optical coupling module is connected to the input of the optical guiding semiconductor module, and the output of the optical guiding semiconductor module is connected to the antenna array module.
[0009] The input of the multi-beam splitter is a high-power laser beam emitted from the laser amplification module, and the output is several high-power laser beams with equal angles and equal intensities. The optical path adjustment module includes several D-shaped mirrors arranged in an equidistant array, each D-shaped mirror being fixed at a certain angle. The incident ends of the D-shaped mirrors correspond to the high-power laser beams output by the multi-beam splitter, reflecting the several high-power laser beams with equal angles and equal intensities output by the multi-beam splitter into parallel laser beams that are emitted out.
[0010] The spatial optical delay module includes several fixed mirror groups, a horizontal displacement stage, and several movable mirror groups. The output optical path of the first output end of the optical path adjustment module does not have fixed or movable mirror groups. The fixed mirror groups are sequentially positioned opposite to the other output ends of the optical path adjustment module (excluding the first output end) and fixed to the base surface. The movable mirror groups are positioned on the horizontal displacement stage and sequentially parallel to the fixed mirror groups, with equal distances between each pair of fixed and movable mirror groups. The horizontal displacement stage is located on the base surface and connected to a host computer.
[0011] In each pair of fixed and movable mirror groups, the number of fixed and movable mirrors is the same; the number of mirrors in the fixed and movable mirror groups increases arithmetically in the order of arrangement, and the number of mirrors in each pair of fixed and movable mirror groups is 4i-4, where i is the optical path number output by the optical path adjustment module, i = 1, 2, 3...n.
[0012] The optical coupler includes at least a focusing lens and a three-dimensional adjuster. The focusing lens is the input end and is connected to the three-dimensional adjuster. The three-dimensional adjuster is fixed with a flange and an optical fiber connector. The optical fiber connector of the three-dimensional adjuster is connected to a multimode optical fiber as the output end.
[0013] A fiber optic delay module is further provided between the output end of the optical coupling module and the input end of the optical guiding semiconductor module. The fiber optic delay module includes an array of fiber optic delay components. The fiber optic delay components include a fiber optic beamsplitter and several optical delay line units. The input end of the fiber optic beamsplitter is connected to the output end of the corresponding optical coupler in the optical coupling module. The optical delay line units are equidistantly arrayed at the output end of the fiber optic beamsplitter. Each optical delay line unit includes an optical delay line for azimuth angle optical delay adjustment and a compensation fiber for azimuth angle phase compensation. The incident end of the optical delay line is connected to the output end of the fiber optic beamsplitter through the compensation fiber, and the emitting end of the optical delay line is connected to the input end of the corresponding optical guiding semiconductor device in the optical guiding semiconductor module through a multimode fiber. In the fiber optic delay components, the delay length of the optical delay lines in the optical delay line units decreases arithmetically from the array edge to the array center, while the length of the compensation fiber increases arithmetically. The optical delay lines are arranged centrally symmetrically along the array center.
[0014] The optical semiconductor module includes several arrayed optical semiconductor devices (PCSS devices), and the input end of each optical semiconductor device is connected to the corresponding output end of the optical fiber delay component; the antenna array module includes several arrayed antenna elements, and the output end of the optical semiconductor device is connected to the corresponding antenna element in the antenna array module through an RF adapter.
[0015] Working principle of the invention:
[0016] The signal generator produces a weak electrical signal with adjustable repetition rate and pulse width. This signal is input to the first electro-optic modulator to externally modulate the macropulse frequency and envelope of the laser output from the narrowband semiconductor laser. The arbitrary waveform generator produces a GHz-level master frequency signal, which is input to the second electro-optic modulator to externally modulate the master frequency of the laser output from the first electro-optic modulator. The signal generator and the arbitrary waveform generator can be connected to a host computer via a data cable, providing programmable control and adjustment capabilities. The laser output from the second electro-optic modulator is considered the seed light source of the system, featuring flexible adjustment of parameters such as master frequency, repetition rate, and pulse width.
[0017] The seed light source, modulated by the second electro-optic modulator, is input to the laser amplification module through an optical isolator. The optical isolator prevents the backward-transmitted laser from the laser amplification module from damaging the second electro-optic modulator. The laser amplification module amplifies the seed light source, significantly increasing the laser power. This ensures that the optical power input to the photoconductor remains at a high level after subsequent beam splitting and delay, ensuring that the trigger laser power exceeds the response threshold of the photoconductor and remains within its linear operating region.
[0018] The magnified laser input to the beam splitter is divided into n equal laser beams, which are output at equal angles to the optical path adjustment module directly in front. Preferably, the beam splitter uses a cascaded grating beam splitter, which spatially modulates the input laser using the principle of diffraction, thereby achieving beam splitting in the far field. The angle between the beams and the position of the beam distribution are controllable. This beam splitter, used in conjunction with a focusing lens, achieves collimated output, causing n light spots of equal intensity to converge and form an image on the focal plane.
[0019] Multiple beams emitted by the multi-beam splitter enter from the corresponding incident ends of the optical path adjustment module, and are reflected by the D-type mirror in the optical path adjustment module to output multiple parallel beams with a sufficiently large spacing, which then enter sequentially from the corresponding input end of the spatial light delay module.
[0020] In the spatial optical delay module, among the parallel laser beams output by the optical path adjustment module, the first laser beam from the first output end directly enters the corresponding optical coupler in the optical coupling module without being reflected by the fixed and movable mirror groups. Laser beams from other output ends are reflected by the fixed and movable mirror groups respectively, and are finally emitted by the fixed mirror group and enter the corresponding optical couplers in the optical coupling module. The horizontal displacement stage in the spatial optical delay module is controlled by the host computer to adjust the distance ΔL between the movable and fixed mirror groups. The mirrors in the fixed and movable mirror groups increase in arithmetic progression from top to bottom, achieving arithmetic progression of delay, which, combined with the movement of the horizontal displacement stage, achieves pitch angle scanning.
[0021] The optical coupling module outputs several laser beams with equal arithmetic delays. To achieve bidirectional elevation angle scanning, the input fiber section before the fiber delay module should undergo length compensation; the compensation length corresponding to the i-th fiber is... Where i = 1, 2, ..., n; D y For the longitudinal aperture of the array, The range is the unidirectional elevation angle scanning range, and n is the number of laser beams output by the optical coupling module.
[0022] This invention combines spatial delay and fiber delay by adding an optical fiber delay module. By combining the advantages of both, it improves the system's delay accuracy and speed, making it easier to adapt to different topologies. The optical fiber delay components in the optical fiber delay module are arranged in a longitudinal array, with the number equal to the number of optical couplers in the optical coupling module, and are sequentially positioned corresponding to the optical couplers. Each laser beam output from the optical coupling module is injected into an optical fiber delay component within the optical fiber delay module. Each optical fiber delay component's optical fiber beamsplitter receives the output laser beam from the corresponding optical coupler and further divides it into several beams, which are then emitted in a laterally equidistant array. The optical fiber delay module outputs a total of n×m beam arrays, where m is the number of beams emitted by each optical fiber beamsplitter, and the intensity uniformity meets the requirements of a phased array.
[0023] The optical delay line unit in the fiber delay module provides a rapidly adjustable optical delay with a large delay span for each laser beam output from the fiber optic beam splitter, forming a true delay unit for azimuth scanning. Specifically, in the fiber delay assembly, the delay length of the optical delay lines in the optical delay line unit decreases arithmetically from the array edge to the array center, while the length of the compensation fiber increases arithmetically. The optical delay lines are arranged centrally symmetrically along the array center, achieving high-precision adjustment while saving the length of the optical delay lines. The optical delay line unit has m / 2 types of optical delay lines and compensation fibers, with m being an even number by default. If m is odd, then m optical delay lines of (m+1) / 2 types are used. The length of the j-th compensation fiber in each fiber delay assembly is 0.5λ(j-1)tan(90°-θ), where λ is the wavelength, j≤m / 2, and θ is the required azimuth unidirectional scanning range. Following this is the optical delay line, and the required delay range for each optical delay line is D. x tanθ(mj) / (m-1)-0.5λ(j-1)tan(90°-θ), where, D x Let j be the transverse aperture of the array, and j ≤ m / 2. Due to the symmetry of the structure, the lengths of the portions j ≥ m / 2 are symmetrically distributed with respect to the lengths of the portions j ≤ m / 2.
[0024] The fiber delay module provides a rapidly adjustable optical path delay for n×m array elements. The output n×m laser beams are transmitted equidistantly via equal-length multimode fibers and then incident on the corresponding photoconductor semiconductor devices in the photoconductor semiconductor module. The multimode fibers are fixed to the photoconductor semiconductor devices via D80 matching connectors. A delay calibration is performed before terminal radiation, and the fiber length is adjusted by measuring weak light signals to reduce errors introduced by various front-end components.
[0025] The photoconductive semiconductor device is located in the high-voltage pulse power supply circuit and is connected in series with the output load (antenna element). The resistance of the photoconductive semiconductor device is inversely proportional to the incident light power, thus making the load output power directly proportional to the incident light power. When laser light is incident, the voltage drop across the photoconductive semiconductor device decreases, increasing the radiated power of the load (antenna element) connected in series. The photoconductive semiconductor module is crucial for achieving high photoelectric conversion efficiency and RF amplification efficiency in the system.
[0026] Each antenna element in the antenna array module is connected to the RF output connector of the corresponding RF semiconductor device in the RF semiconductor module, radiating the RF signal after true delay to achieve power combining and beam scanning of the planar phased array antenna.
[0027] To address the low radiation efficiency of unipolar output and ensure that the phase difference between the signals applied to the two photoconductive semiconductors of the same element remains constant while relative phase adjustment is performed between different array elements, this invention also provides a high-power tunable optical true-delay one-dimensional phased array transmission system based on photoconductive devices. This system employs a push-pull amplification method to convert non-zero-crossing signals into zero-crossing signals, resulting in an all-AC output signal that is easily radiated. The optical true-delay one-dimensional phased array transmission system includes a signal generator, a narrowband semiconductor laser, an arbitrary waveform generator, a first electro-optic modulator, a second electro-optic modulator, an optical isolator, a phase delay module, a laser amplification module, a beam splitter, an optical path adjustment module, a spatial optical delay module, an optical coupling module, a photoconductive semiconductor module, and an antenna array module.
[0028] The connection method of the signal generator, narrowband semiconductor laser, arbitrary waveform generator, first electro-optic modulator, second electro-optic modulator, and optical isolator is the same as that of the optical true delay phased array transmission system described above, and will not be repeated here. The difference is that the output end of the optical isolator is connected to the phase delay module. The phase delay module includes an optical coupling submodule, a pair of optical circulators, and an adjustable mirror group. The input end of the optical coupling submodule is connected to the output end of the optical isolator, and the output end of the optical coupling submodule is connected to the first port of the optical circulator. The second port of the optical circulator is positioned opposite to the adjustable mirror group through an optical fiber collimator. The third port of the optical circulator is the output end of the phase delay module.
[0029] The adjustable mirror assembly used in push-pull amplification includes a fixed mirror and a movable mirror. The movable mirror is connected to a stepper motor, and its one-dimensional displacement is achieved by driving the stepper motor, thereby changing the mirror assembly spacing L0. The relationship between the mirror assembly spacing L0 and the main frequency is as follows:
[0030]
[0031] Where c is the speed of light, τ is the optical signal delay, and f is the modulation frequency.
[0032] The laser amplification module includes two identical laser amplifiers. The input terminals of the two laser amplifiers are respectively connected to the third port of the optical circulator, and the output terminals are respectively connected to the multiplexer. The connection method of the multiplexer, optical path adjustment module, spatial optical delay module, and optical coupling module is the same as that of the aforementioned optical true delay phased array transmission system, and will not be repeated here. The photoconductive semiconductor module includes several arrayed photoconductive semiconductor components. Each photoconductive semiconductor component includes two parallel photoconductive semiconductors, two pulse power sources with opposite polarities, and a combiner. The two photoconductive semiconductors are respectively connected to the two pulse power sources, and the pulse power sources supply power to the photoconductive semiconductors. The input terminals of the two photoconductive semiconductors are respectively connected to the corresponding optical couplers in the optical coupling module, the output terminals of the two photoconductive semiconductors are connected to the input terminals of the combiner, and the output terminals of the combiner are connected to the corresponding antenna elements in the antenna array module.
[0033] The working principle of the high-power tunable optical true delay one-dimensional phased array transmission system based on optical guide devices is as follows:
[0034] Its implementation principle is basically the same as the working principle described above. The differences are described below:
[0035] The seed light source output from the optical isolator is input into the phase delay module. After 1×2 beam splitting by the optical coupling submodule within the phase delay module, the light is input to the first port of the optical circulator. The output light exits from the second port of the optical circulator and is connected to the fiber optic collimator via a pigtail fusion splice. The laser emitted from the fiber optic collimator is perpendicular to the adjustable mirror assembly. One of the two mirrors in the adjustable mirror assembly is fixed, while the other can be driven by a stepper motor to achieve one-dimensional displacement, thus making the mirror spacing L0 adjustable. By adjusting the stepper motor according to the change in the dominant frequency f, a fixed phase difference that varies with the dominant frequency can be achieved. After the reflected light passes through the collimator and enters the second port of the optical circulator, it exits from the third port of the optical circulator, which is the output of the phase delay module. After being output from the phase delay module, the two laser beams enter two identical laser amplifiers in the laser amplification module. The amplified laser beams share a multiplexer to achieve uniform beam splitting at different spatial angles. Then, the optical path is adjusted by a D-shaped mirror in the optical path adjustment module. After that, every two laser beams with a certain phase difference share a spatial optical delay module. After being processed by the spatial optical delay module, the beams are output to the corresponding optical guiding semiconductor components in the optical coupling module through the optical coupler in the optical coupling module. In each group of optical guiding semiconductor components, two parallel optical guiding semiconductors receive the two laser beams, and the output radio frequency signals are combined by a combiner and input to the corresponding antenna element in the antenna array module to radiate the radio frequency signals after true delay.
[0036] The beneficial effects of this invention are:
[0037] This invention leverages the advantages of single-path optical guide devices to perform array power combining, constructing a high-power tunable optical true-delay phased array transmission system. It employs a method combining spatial and fiber delay, integrating the advantages of both to improve system delay accuracy and speed, and making it easier to topologically adapt. Multiple high-power pulsed lasers are input into an equal number of optical guide devices, achieving photoelectric conversion and RF power amplification. The amplified electrical signals are input into an equal number of phased array elements through RF connectors, achieving single-source power at the hundreds of kilowatt level through spatial radiation and power combining. The linear operating mode of the optical guide devices allows their output parameters to be adjusted using weak electrical signals from signal generators, thus giving the system a multi-parameter flexible adjustable characteristic, with its main frequency P-L band continuously adjustable. This invention features ultra-wideband low loss, strong anti-radiation interference capability, multi-parameter flexible adjustment, and wide bandwidth angle scanning, providing a reference for the practical application of optical guide semiconductor devices in high-power microwave sources. Attached Figure Description
[0038] Figure 1 This is a schematic diagram of the overall structure of Embodiment 1 of the present invention;
[0039] Figure 2 This is a schematic diagram of the spatial optical delay module structure of the present invention;
[0040] Figure 3 This is a schematic diagram of the fiber delay module structure according to Embodiment 1 of the present invention;
[0041] Figure 4 This is a schematic diagram of the overall structure of Embodiment 2 of the present invention;
[0042] Figure 5 This is a schematic diagram of the two-π phase delay module structure according to an embodiment of the present invention;
[0043] Figure 6 This is a schematic diagram of the single-pulse push-pull and continuous-wave push-pull test results in Embodiment 2 of the present invention;
[0044] 1. Signal generator; 2. Narrowband semiconductor laser; 3. Arbitrary waveform generator; 4. First electro-optic modulator; 5. Second electro-optic modulator; 6. Optical isolator.
[0045] 7. Laser Amplification Module 701, Laser Amplifier;
[0046] 8. Multi-channel splitter;
[0047] 9. Optical path adjustment module 901; D-shaped reflector;
[0048] 10. Spatial light delay module 1001, fixed reflector group 1002, horizontal displacement stage 1003, moving reflector group;
[0049] 11. Optical coupling module 1101. Optical coupler;
[0050] 12. Optical semiconductor module 1201. Optical semiconductor device;
[0051] 13. Antenna array module 1301, antenna element;
[0052] 14. Fiber optic delay module 1401, fiber optic delay assembly 1402, fiber optic beam splitter 1403, optical delay line unit 1404, optical delay line 1405, compensation fiber;
[0053] 15. π phase delay module 1501, optical coupling submodule 1502, optical circulator 1503, adjustable reflector group. Detailed Implementation
[0054] Example 1
[0055] See Figure 1-3As shown: This embodiment provides a high-power tunable optical true-delay phased array transmission system based on optical guide devices, including a signal generator 1, a narrowband semiconductor laser 2, an arbitrary waveform generator 3, a first electro-optic modulator 4, a second electro-optic modulator 5, an optical isolator 6, a laser amplification module 7, a multiplexer 8, an optical path adjustment module 9, a spatial optical delay module 10, an optical coupling module 11, an optical guide semiconductor module 12, and an antenna array module 13;
[0056] The output terminal of the signal generator 1 is connected to the electrical input terminal of the first electro-optic modulator 4, and the output terminal of the narrowband semiconductor laser 2 is connected to the optical input terminal of the first electro-optic modulator 4. The output terminal of the first electro-optic modulator 4 is connected to the electrical input terminal of the second electro-optic modulator 5, and the output terminal of the arbitrary waveform generator 3 is connected to the optical input terminal of the second electro-optic modulator 5. The output terminal of the second electro-optic modulator 5 is connected to the input terminal of the optical isolator 6, and the output terminal of the optical isolator 6 is connected to the input terminal of the laser amplification module 7 through an optical fiber collimator. The output terminal of the laser amplification module 7 is connected to the input terminal of the laser amplification module 7 through an optical fiber collimator. The optical coupling module 11 is connected to the input of the multi-channel beam splitter 8, and the output of the multi-channel beam splitter 8 is connected to the input of the optical path adjustment module 9. The output of the optical path adjustment module 9 is opposite to the input of the spatial optical delay module 10. The optical coupling module 11 includes n arrayed optical couplers 1101, and the input of each optical coupler 1101 is opposite to the output of the corresponding spatial optical delay module 10. The output of the optical coupling module 11 is connected to the input of the optical guiding semiconductor module 12, and the output of the optical guiding semiconductor module 12 is connected to the antenna array module 13 through an RF adapter.
[0057] The input of the multi-beam splitter 8 is a high-power laser beam emitted from the laser amplification module 7, and the output is n high-power laser beams with equal angles and equal intensities. The optical path adjustment module 9 includes n D-shaped reflectors 901 arranged in an equidistant array, each D-shaped reflector 901 being fixed at a certain angle. The incident ends of the D-shaped reflectors 901 correspond to the high-power laser beams output from the multi-beam splitter 8, reflecting the n high-power laser beams with equal angles and equal intensities output from the multi-beam splitter 8 into n parallel laser beams that are emitted.
[0058] The spatial light delay module 10 includes (n-1) fixed reflector groups 1001, a horizontal displacement stage 1002, and (n-1) movable reflector groups 1003. The output light path of the first output end of the optical path adjustment module 9 does not have fixed reflector groups 1001 or movable reflector groups 1003. The fixed reflector groups 1001 are sequentially arranged opposite to the other output ends of the optical path adjustment module 9 (excluding the first output end) and fixed on the base surface. The movable reflector groups 1003 are arranged on the horizontal displacement stage 1002, sequentially parallel to the fixed reflector groups 1001, with equal distances between each pair of fixed reflector groups 1001 and movable reflector groups 1003. The horizontal displacement stage 1002 is located on the base surface and connected to the host computer.
[0059] In each pair of fixed mirror group 1001 and movable mirror group 1003, the number of fixed mirrors and movable mirrors is the same; the number of mirrors in the fixed mirror group 1001 and movable mirror group 1003 increases arithmetically from top to bottom, and the number of mirrors in each pair of fixed mirror group 1001 and movable mirror group 1003 is 4i-4 (see...). Figure 2 (0 for the first path, 4 for the second path, and 8 for the third path), where i is the optical path number output by the optical path adjustment module 9, i = 1, 2, 3...n; this makes the number of spatial light folds increase sequentially, providing continuously adjustable and equally distributed optical delay for each laser beam output by the multi-path beam splitter, thus forming a true delay unit for elevation angle scanning.
[0060] In the spatial optical delay module 10, the optical path differences corresponding to each row of array elements are 0, 2ΔL, 4ΔL, ... (2n-2)ΔL, where ΔL is the distance between the front and rear mirror groups. The required maximum value of ΔL is determined by the pitch angle. The value is determined by the radiation frequency f, and its maximum value is There are requirements for the upper limit of the moving length of the horizontal displacement stage 1002 and the separation angle of the spatial beam splitter. The horizontal displacement stage 1002 is controlled by the host computer through a serial port. When the horizontal displacement stage 1002 moves, the moving mirror group 1003 moves accordingly. Theoretically, when ΔL is scanned from 0mm to 129.9mm, a scanning of pitch angle ±60° can be completed.
[0061] The optical coupler 1101 includes at least a focusing lens and a three-dimensional adjuster. The focusing lens is the input end and is connected to the three-dimensional adjuster. A flange and a D80 fiber optic connector are fixed on the three-dimensional adjuster. The D80 fiber optic connector of the three-dimensional adjuster is connected to a multimode fiber as the output end.
[0062] A fiber optic delay module 14 is further provided between the output end of the optical coupling module 11 and the input end of the photoconductive semiconductor module 12. The fiber optic delay module 14 includes n sets of vertically arrayed fiber optic delay components 1401. Each fiber optic delay component 1401 includes a fiber optic beamsplitter 1402 and m optical delay line units 1403. The input end of the fiber optic beamsplitter 1402 is connected to the output end of the corresponding optical coupler 1101 in the optical coupling module 11. The m optical delay line units 1403 are horizontally equidistantly arrayed at the output end of the fiber optic beamsplitter 1402. The fiber optic beamsplitter 1402 is connected to the subsequent optical delay line units 1403 via pigtail fusion splices. The delay line unit 1403 includes an optical delay line 1404 for azimuth angle optical delay adjustment and a compensation fiber 1405 for azimuth angle phase compensation. The incident end of the optical delay line 1404 is connected to the output end of the fiber optic beam splitter 1402 through the compensation fiber 1405, and the emitting end of the optical delay line 1404 is connected to the input end of the corresponding optical guiding semiconductor device 1201 in the optical guiding semiconductor module 12 through a multimode fiber of equal length. In each group of fiber delay components 1401, the delay length of the optical delay line 1404 in the optical delay line unit 1403 decreases arithmetically from the array edge to the array center, and the length of the compensation fiber 1405 increases arithmetically. The optical delay line 1404 is arranged in a centrally symmetrical manner along the array center.
[0063] The optical semiconductor module 12 includes n×m optical semiconductor devices 1201 arranged in an array, and the input end of each optical semiconductor device 1201 is connected to the corresponding output end of the optical fiber delay component 1401; the antenna array module 13 includes n×m antenna elements 1301 arranged in an array, and the output end of the optical semiconductor device 1201 is connected to the corresponding antenna element 1301 in the antenna array module 13 through an RF adapter.
[0064] The working principle of this embodiment:
[0065] The signal generator 1 generates a weak electrical signal with adjustable repetition rate and pulse width. This signal is input to the first electro-optic modulator 4 to externally modulate the macropulse frequency and envelope of the laser output from the narrowband semiconductor laser 2. The arbitrary waveform generator 3 generates a GHz-level master frequency signal, which is input to the second electro-optic modulator 5 to externally modulate the master frequency of the laser output from the first electro-optic modulator 4. The signal generator 1 and the arbitrary waveform generator 3 can be connected to a host computer via a data line (such as RS232) and have programmable control and adjustment capabilities. The laser output from the second electro-optic modulator 5 is considered as the seed light source of the system, and its master frequency, repetition rate, and pulse width are flexibly adjustable.
[0066] The seed light source, modulated by the second electro-optic modulator 5, is input to the laser amplification module 7 via an optical isolator 6. The optical isolator 6 prevents the backward-transmitted laser light from the laser amplification module 7 from damaging the second electro-optic modulator 5. The laser amplification module 7 amplifies the seed light source, significantly increasing the laser power. This ensures that the optical power input to the photoconductor after subsequent beam splitting and delay remains at a high level, ensuring that the trigger laser power exceeds the response threshold of the photoconductor and remains within the linear operating region of the device.
[0067] The magnified laser input to the multiplexer 8 is divided into n equal laser beams, which are output at equal angles to the optical path adjustment module 9 directly in front. Preferably, the multiplexer 8 is a cascaded grating beam splitter. This beam splitter uses the principle of diffraction to spatially modulate the input laser, thereby achieving beam splitting in the far field. The angle between the beams and the position of the beam distribution are controllable. This beam splitter, in conjunction with a focusing lens, achieves collimated output, causing n light spots of equal intensity to converge and form an image on the focal plane.
[0068] The n beams emitted by the multi-beam splitter 8 are respectively injected into the corresponding incident ends of the optical path adjustment module 9. After being reflected by the D-type reflector in the optical path adjustment module 9, n parallel beams with a sufficiently large spacing are output and are sequentially injected into the corresponding input ends of the spatial light delay module 10.
[0069] In the spatial optical delay module 10, among the parallel laser beams output by the optical path adjustment module 9, the first laser beam output from the first output end directly enters the corresponding optical coupler 1101 in the optical coupling module 11 without being reflected by the fixed reflector group 1001 and the moving reflector group 1003. The laser beams output from the other output ends besides the first output end are reflected by the fixed reflector group 1001 and the moving reflector group 1003 respectively, and are finally emitted by the fixed reflector group 1001 and enter the corresponding optical coupler 1101 in the optical coupling module 11. The horizontal displacement stage 1002 in the spatial optical delay module 10 is controlled by the host computer to perform horizontal displacement, adjusting the distance ΔL between the moving reflector group 1003 and the fixed reflector group 1001. The mirrors in the fixed reflector group 1001 and the moving reflector group 1003 increase in arithmetic progression from top to bottom to achieve arithmetic progression of delay, and the movement of the horizontal displacement stage 1002 achieves pitch angle scanning.
[0070] Optical coupling module 11 outputs several laser beams with equal arithmetic delay distributions. To achieve bidirectional elevation angle scanning, the input fiber section before fiber delay module 14 should undergo length compensation, with the compensation length corresponding to the i-th fiber being... Where i = 1, 2, ..., n; Dy is the longitudinal aperture of the array. The range is the unidirectional elevation angle scanning range, and n is the number of laser beams output by the optical coupling module.
[0071] This embodiment combines spatial delay and fiber delay by adding an optical fiber delay module 14. By combining the advantages of both, the system's delay accuracy and speed are improved. The optical fiber delay module 14 includes n longitudinally arrayed optical fiber delay components 1401, sequentially corresponding to optical couplers 1101. Each laser beam output from the optical coupler module 11 is injected into its corresponding optical fiber delay component 1401 within the optical fiber delay module 14. The optical fiber beam splitter 1402 in each optical fiber delay component 1401 receives the output laser beam from the corresponding optical coupler 1101 and further divides it into m beams, which are emitted in a laterally equidistant array. The optical fiber delay module 14 outputs a total of n×m beam arrays, whose intensity uniformity meets the requirements of a phased array.
[0072] The optical delay line unit 1403 in the fiber delay module 14 provides a rapidly adjustable optical delay with a large delay span for each laser beam output by the fiber optic beam splitter 1402, forming an azimuth angle scanning true delay unit. Specifically, in the fiber delay assembly 1401, the delay lengths of the optical delay lines 1404 in the optical delay line unit 1403 decrease arithmetically from the array edge to the array center, while the lengths of the compensation fibers 1405 increase arithmetically. The optical delay lines 1404 are arranged centrally symmetrically along the array center, achieving high-precision adjustment while saving the length of the optical delay lines 1404. Component 1403 has optical delay lines 1404 of m / 2 different lengths and compensation fibers 1405. The default value for m is even; if m is odd, then m optical delay lines 1404 of (m+1) / 2 different types are used. In this embodiment, assuming the required azimuth scanning range is ±60°, the length of the j-th compensation fiber 1405 in each fiber delay component 1401 is 0.5λ(j-1)tan30°=86.7×(j-1)(mm), where λ is the wavelength and j≤m / 2. This is followed by optical delay lines 1404, and the required delay range for each optical delay line 1404 is D. x tanθ(mj) / (m-1)-0.5λ(j-1)tan(30°)mm, where D x Let j be the transverse aperture of the array, and j ≤ m / 2. Due to the symmetry of the structure, the lengths of the portions j ≥ m / 2 are symmetrically distributed with respect to the lengths of the portions j ≤ m / 2.
[0073] The fiber delay module 14 provides a rapidly adjustable optical path delay for n×m array elements, enabling azimuth angle scanning of ±60°. The output n×m laser beams are transmitted equidistantly via equal-length multimode fibers and then incident on the corresponding optical guiding semiconductor device 1201 in the optical guiding semiconductor module 12. The multimode fiber is fixed to the optical guiding semiconductor device 1201 via a D80 matching connector. A delay calibration is performed before terminal radiation, and the fiber length is adjusted by measuring weak light signals to reduce errors introduced by various front-end components.
[0074] The photoconductor semiconductor device (6H-SiC PCSS Devices) 1201 is located in the high-voltage pulse power supply circuit and is connected in series with the output load (antenna unit 1301). The resistance of the photoconductor semiconductor device 1201 is inversely proportional to the incident light power, thus making the load output power directly proportional to the incident light power. When laser light is incident, the voltage drop across the photoconductor semiconductor device 1201 decreases, increasing the radiated power of the load (antenna unit 1301) connected in series with it. The photoconductor semiconductor module 12 is crucial for achieving high photoelectric conversion efficiency and RF amplification efficiency in the system.
[0075] Each antenna element 1301 in the antenna array module 13 is connected to the RF output connector of the corresponding RF semiconductor device 1201 in the RF semiconductor module 12, radiating the RF signal after true delay to realize power synthesis and beam scanning of the planar phased array antenna.
[0076] Example 2
[0077] See Figure 4-5 As shown: This embodiment provides a high-power tunable optical true-delay one-dimensional phased array transmitting system based on optical guide devices. It employs a push-pull amplification method to convert non-zero-crossing signals into zero-crossing signals, resulting in an all-AC output signal. The optical true-delay one-dimensional phased array transmitting system includes a signal generator 1, a narrowband semiconductor laser 2, an arbitrary waveform generator 3, a first electro-optic modulator 4, a second electro-optic modulator 5, an optical isolator 6, a π-phase delay module 15, a laser amplification module 7, a multiplexer 8, an optical path adjustment module 9, a spatial optical delay module 10, an optical coupling module 11, an optical guide semiconductor module 12, and an antenna array module 13.
[0078] The connection methods of the signal generator 1, narrowband semiconductor laser 2, arbitrary waveform generator 3, first electro-optic modulator 4, second electro-optic modulator 5 and optical isolator 6, as well as the connection methods of the multi-channel beam splitter 8, optical path adjustment module 9, spatial optical delay module 10 and optical coupling module 11 are the same as those of the optical true delay phased array transmission system described in Embodiment 1, and will not be repeated here.
[0079] The requirement is that while relative phase adjustment is performed between different array elements, the phase difference of the signals applied to the two photoconductive semiconductors of the same array element remains constant at π, that is, the optical signal delay τ is adjusted accordingly as the modulation frequency f changes.
[0080] Therefore, the difference in this embodiment is that the output end of the optical isolator 6 is connected to the π phase delay module 15. The π phase delay module 15 includes an optical coupling submodule 1501, a pair of optical circulators 1502, and an adjustable mirror group 1503. The input end of the optical coupling submodule 1501 is connected to the output end of the optical isolator 6, and the output end of the optical coupling submodule 1501 is connected to the first port of the optical circulator 1502. The second port of the optical circulator 1502 is opposite to the adjustable mirror group 1503 through an optical fiber collimator. The third port of the optical circulator 1502 is the output end of the π phase delay module 15.
[0081] The adjustable reflector assembly 1503 includes a fixed reflector and a movable reflector. The movable reflector is connected to a stepper motor, and its one-dimensional displacement is achieved by driving the stepper motor, thereby changing the distance L0 between the reflectors. The relationship between the distance L0 between the reflectors and the main frequency is as follows:
[0082]
[0083] Where c is the speed of light, τ is the optical signal delay, and f is the modulation frequency.
[0084] The laser amplification module 7 includes two identical laser amplifiers 701 and 702. The input terminals of laser amplifiers 701 and 702 are respectively connected to the third port of optical circulator 1502, and the output terminals are respectively connected to multiplexer 8.
[0085] The optical semiconductor module 12 includes n arrayed optical semiconductor components 1202. Each optical semiconductor component 1202 includes two parallel optical semiconductors 1203, two pulse power sources 1204 with opposite polarities, and a combiner 1205. The two optical semiconductors 1203 are respectively connected to the two pulse power sources 1204, and the pulse power sources 1204 supply power to the optical semiconductors 1203. The input terminals of the two optical semiconductors 1203 are respectively connected to the corresponding optical couplers 1101 in the optical coupling module 11, and the output terminals of the two optical semiconductors 1203 are connected to the input terminals of the combiner 1205. The output terminal of the combiner 1205 is connected to the corresponding antenna element 1301 in the antenna array module 13.
[0086] The working principle of this embodiment:
[0087] Its implementation principle is basically the same as that of Embodiment 1. The differences are described below:
[0088] The seed light source output from the optical isolator 6 is input into the π-phase delay module 15. After 1×2 beam splitting by the optical coupling submodule 1501 in the π-phase delay module 15, the light is input to the first port of the optical circulator 1502. The output light exits from the second port of the optical circulator 1502 and is connected to the fiber optic collimator via a pigtail fusion splice. The laser emitted from the fiber optic collimator is perpendicular to the adjustable mirror group 1503. One of the two mirrors in the adjustable mirror group 1503 is fixed, while the other can be driven by a stepper motor to achieve one-dimensional displacement, thus the mirror spacing L0 is adjustable. By adjusting the stepper motor according to the change of the main frequency f, a fixed phase difference that changes with the main frequency can be achieved. After the reflected light passes through the collimator and enters the second port of the optical circulator 1502, it exits from the third port of the optical circulator 1502, that is, the output end of the π-phase delay module 15. After two laser beams are output from the π phase delay module 15, they enter two identical laser amplifiers 701 in the laser amplification module 7. The amplified laser beams share a multiplexer 8 to achieve uniform beam splitting at different spatial angles. Then, the optical path is adjusted by the D-shaped reflector 901 in the optical path adjustment module 9. After that, every two laser beams with a certain phase difference share a spatial optical delay module 10. After being processed by the spatial optical delay module 10, the beams are output to the corresponding optical guiding semiconductor component 1202 in the optical guiding semiconductor module 12 through the optical coupler 1101 in the optical coupling module 11. In each group of optical guiding semiconductor components 1202, two parallel optical guiding semiconductors receive the two laser beams, and the output radio frequency signals are combined by a combiner and input to the corresponding antenna element 1301 in the antenna array module 13 to radiate the radio frequency signals after true delay.
[0089] A simulation model of a dual-path optical guide device and an RF beam combiner was constructed, and preliminary verifications were performed on single-pulse push-pull and continuous-wave push-pull models, with the output results as follows: Figure 6 As shown, (a) and (c) are time-domain output signals, and (b) and (d) are frequency-domain output signals, proving the feasibility of combining push-pull beamforming with time delay.
Claims
1. A high-power tunable optical true-delay phased array transmission system based on an optical guide device, characterized in that: It includes a signal generator, a narrowband semiconductor laser, an arbitrary waveform generator, a first electro-optic modulator, a second electro-optic modulator, an optical isolator, a laser amplification module, a multiplexer, an optical path adjustment module, a spatial optical delay module, an optical coupling module, a photoconductive semiconductor module, and an antenna array module; The output of the signal generator is connected to the electrical input of the first electro-optic modulator, and the output of the narrowband semiconductor laser is connected to the optical input of the first electro-optic modulator. The output of the first electro-optic modulator is connected to the optical input of the second electro-optic modulator, and the output of the arbitrary waveform generator is connected to the electrical input of the second electro-optic modulator. The output of the second electro-optic modulator is connected to the input of the optical isolator, and the output of the optical isolator is connected to the input of the laser amplification module. The output of the laser amplification module is connected to the input of the multi-channel beam splitter, and the output of the multi-channel beam splitter is connected to the input of the optical path adjustment module. The output of the optical path adjustment module is positioned opposite to the input of the spatial optical delay module. The optical coupling module includes several arrayed optical... The input terminals of the optical couplers are respectively positioned opposite to the output terminals of the corresponding spatial optical delay modules; the output terminals of the optical couplers are connected to the input terminals of the optical guiding semiconductor modules, and the output terminals of the optical guiding semiconductor modules are connected to the antenna array modules; the input of the multi-channel beam splitter is a high-power laser beam emitted from the laser amplification module, and the output is several high-power laser beams with equal angles and equal intensities; the spatial optical delay module includes several fixed mirror groups, a horizontal displacement stage, and several movable mirror groups; in each pair of fixed mirror groups and movable mirror groups, the number of fixed mirrors and movable mirrors is the same, and the total number of fixed mirrors plus movable mirrors is 4i-4, where i is the optical path number output by the optical path adjustment module, i=1, 2, 3...n; A fiber optic delay module is further provided between the output end of the optical coupling module and the input end of the optical guiding semiconductor module. The fiber optic delay module includes an array of fiber optic delay components. The fiber optic delay components include a fiber optic beamsplitter and several optical delay line units. The input end of the fiber optic beamsplitter is connected to the output end of the corresponding optical coupler in the optical coupling module. The optical delay line units are equidistantly arrayed at the output end of the fiber optic beamsplitter. In the fiber optic delay components, the delay length of the optical delay lines in the optical delay line units from the edge of the array to the center of the array decreases arithmetically, while the length of the compensating fiber increases arithmetically. The optical delay lines are arranged centrally symmetrically along the center of the array.
2. The high-power tunable optical true-delay phased array transmission system based on an optical guide device according to claim 1, characterized in that: The optical path adjustment module includes several D-shaped reflectors arranged in an equidistant array, each D-shaped reflector being fixed at a certain angle; the incident ends of the D-shaped reflectors correspond to the high-power laser beams output by the multi-channel beam splitter, reflecting the several high-power laser beams of equal angle and intensity output by the multi-channel beam splitter into parallel laser beams that are emitted out.
3. The high-power tunable optical true-delay phased array transmission system based on an optical guide device according to claim 1, characterized in that: The optical path of the first output end of the optical path adjustment module does not have a fixed reflector group or a movable reflector group. The fixed reflector group is arranged in sequence opposite to the other output ends of the optical path adjustment module except for the first output end, and is fixed on the base surface. The movable reflector group is arranged on the horizontal displacement stage and is arranged in sequence parallel to the fixed reflector group. The distance between each pair of fixed reflector groups and movable reflector groups is equal. The horizontal displacement stage is arranged on the base surface and is connected to the host computer.
4. A high-power tunable optical true-delay phased array transmission system based on an optical guide device according to claim 1, characterized in that: The optical delay line unit includes an optical delay line for azimuth angle optical delay adjustment and a compensation fiber for azimuth angle phase compensation. The incident end of the optical delay line is connected to the output end of the fiber optic beam splitter through the compensation fiber. The emitting end of the optical delay line is connected to the input end of the corresponding optical guiding semiconductor device in the optical guiding semiconductor module through a multimode fiber.
5. A high-power tunable optical true-delay phased array transmission system based on an optical guide device according to claim 1, characterized in that: The optical semiconductor module includes several optical semiconductor devices arranged in an array, and the input end of each optical semiconductor device is connected to the corresponding output end of the optical fiber delay component; the antenna array module includes several antenna elements arranged in an array, and the output end of the optical semiconductor device is connected to the corresponding antenna element in the antenna array module through an RF adapter.
6. A high-power tunable optical true-delay phased array transmission system based on an optical guide device, characterized in that: It includes a signal generator, a narrowband semiconductor laser, an arbitrary waveform generator, a first electro-optic modulator, a second electro-optic modulator, an optical isolator, a laser amplification module, a multiplexer, an optical path adjustment module, a spatial optical delay module, an optical coupling module, a photoconductive semiconductor module, and an antenna array module; The output of the signal generator is connected to the electrical input of the first electro-optic modulator, and the output of the narrowband semiconductor laser is connected to the optical input of the first electro-optic modulator. The output of the first electro-optic modulator is connected to the optical input of the second electro-optic modulator, and the output of the arbitrary waveform generator is connected to the electrical input of the second electro-optic modulator. The output of the second electro-optic modulator is connected to the input of the optical isolator, and the output of the optical isolator is connected to the input of the laser amplification module. The output of the laser amplification module is connected to the input of the multi-channel beam splitter, and the output of the multi-channel beam splitter is connected to the input of the optical path adjustment module. The output of the optical path adjustment module is positioned opposite to the input of the spatial optical delay module. The optical coupling module includes several arrayed optical... The input terminals of the optical couplers are respectively positioned opposite to the output terminals of the corresponding spatial optical delay modules; the output terminals of the optical couplers are connected to the input terminals of the optical guiding semiconductor modules, and the output terminals of the optical guiding semiconductor modules are connected to the antenna array modules; the input of the multi-channel beam splitter is a high-power laser beam emitted from the laser amplification module, and the output is several high-power laser beams with equal angles and equal intensities; the spatial optical delay module includes several fixed mirror groups, a horizontal displacement stage, and several movable mirror groups; in each pair of fixed mirror groups and movable mirror groups, the number of fixed mirrors and movable mirrors is the same, and the total number of fixed mirrors plus movable mirrors is 4i-4, where i is the optical path number output by the optical path adjustment module, i=1, 2, 3...n; A phase delay module is provided between the optical isolator and the laser amplification module; The output of the optical isolator is connected to the phase delay module. The phase delay module includes an optical coupling submodule, a pair of optical circulators, and an adjustable mirror group. The input of the optical coupling submodule is connected to the output of the optical isolator, and the output of the optical coupling submodule is connected to the first port of the optical circulator. The second port of the optical circulator is positioned opposite to the adjustable mirror group through an optical fiber collimator. The third port of the optical circulator is the output of the phase delay module. The adjustable reflector assembly includes a fixed reflector and a movable reflector. The movable reflector is connected to a stepper motor, and its one-dimensional displacement is achieved by driving the stepper motor, thereby changing the spacing L0 between the reflectors. The relationship between the spacing L0 and the main frequency is as follows: Where c is the speed of light. f is the optical signal delay, and f is the modulation frequency.
7. A high-power tunable optical true-delay phased array transmission system based on an optical guide device according to claim 6, characterized in that: The laser amplification module includes two identical laser amplifiers, the input terminals of which are respectively connected to the third port of the optical circulator, and the output terminals of which are respectively connected to the multiplexer; the optical guiding semiconductor module includes several arrayed optical guiding semiconductor components, each of which includes two parallel optical guiding semiconductors, two pulse power sources with opposite polarities, and a combiner, with the two optical guiding semiconductors respectively connected to the two pulse power sources, and the pulse power sources supplying power to the optical guiding semiconductors; The input terminals of the two photoconductive semiconductors are connected to the corresponding optical couplers in the optical coupling module, the output terminals of the two photoconductive semiconductors are connected to the input terminals of the combiner, and the output terminals of the combiner are connected to the corresponding antenna elements in the antenna array module.