A microwave photonic broadband directly modulated multi-beamforming network system

Abstract

The present invention proposes a microwave photon broadband direct modulation multi-beam forming network system, which relates to the fields of microwave photonics, true time delay beam forming, broadband multi-beam forming, etc. The present invention includes a direct modulation transmission module, an optical delay attenuation module, an optoelectronic conversion module, a beam reconstruction module and a beam control module. The optoelectronic conversion module includes an optical wavelength division multiplexer, an optical amplifier and a photodetector. The direct modulation transmission module includes 2n-way electro-optical direct modulation paths. The optical delay attenuation module includes 2n-way delay attenuation control paths. The 2n-way electro-optical direct modulation paths and the 2n-way delay attenuation control paths are connected in a one-to-one correspondence. The outputs of the 2n-way delay attenuation control paths are all connected to the optical wavelength division multiplexer. Based on the microwave photon direct modulation link and the optical control beam forming network, the present invention can improve the operating frequency band and instantaneous operating bandwidth of the system, and simultaneously realize wide-angle scanning and ultra-wideband, as well as beam splitting mode or beam combining mode, to ensure high-speed, large-capacity and reliable transmission of the application system.

Description

Technical Field

[0001] The present invention belongs to the fields of microwave photonics, true time-delay beamforming, broadband multi-beamforming, and the like, and particularly relates to a microwave photonic broadband direct modulation multi-beamforming network system. Background Art

[0002] Beamforming is a widely used array signal processing technology in fields such as satellite communications, radar, and electronic warfare. Its essence is to improve system performance by weighting the phase and amplitude of the signals transmitted by each channel of the array so that the main lobe of the array radiation pattern is aligned with the intended target and the null is aligned with the interference signal.

[0003] Microwave photonics technology is an emerging technology that integrates microwaves and light waves. It can modulate microwave signals onto optical carriers and generate, process, control and transmit microwave signals in the optical domain. It has many advantages such as broadband, high speed, parallelism and resistance to electromagnetic interference.

[0004] A phased array that uses an optical true-delay phase-shift network based on microwave photonics instead of a traditional electrical phase-shift network is called an optically controlled phased array. Because the RF signal is time-delayed in the optical domain through optical conversion, the optical true-delay phase-shift network inherits the advantages of both microwave and photonic technologies and offers several advantages over traditional electrical phase-shifting, including the following:

[0005] First, it expands the bandwidth of the phased array. Because the optical phase-shifting network implements true time delay for the electrical signal, the system eliminates beam skew and aperture transit time, achieving a wide instantaneous bandwidth. Furthermore, since microwave photonic devices typically have a large bandwidth, microwave signals can be beam-synthesized directly in the optical domain without down-conversion. Second, it reduces signal transmission loss. Optical signal transmission loss in optical fiber is extremely low. The optical transmission loss of a 1550nm laser is typically 0.2dB / km, which translates to an electrical signal loss of 0.4dB / km, which is negligible compared to the loss in coaxial cables or waveguides. Furthermore, because the frequency of microwave signals is much lower than that of light waves, the loss of RF signals of different frequencies in optical fiber is very consistent. Third, it reduces the weight and volume of the system. Optical fiber typically weighs 1.7kg / km, while coaxial cable weighs approximately 567kg / km. Using optical fiber to achieve time delay significantly reduces system weight. Furthermore, quartz fiber has a smaller cross-sectional diameter and smaller bend radius than coaxial cable, further reducing the system's volume. Fourth, anti-electromagnetic interference. Since microwave signals are transmitted through optical fibers on optical carriers, they are not interfered with by external electromagnetic radiation during transmission, and they also do not generate electromagnetic radiation.

[0006] Directly modulated microwave photonic links offer advantages such as simple structure, low cost, and ease of implementation, making them ideal for large-scale beamforming networks. Direct modulation involves directly modulating the RF signal onto an optical carrier wave using a directly modulated laser. By varying the laser's drive current, the intensity of the output lightwave changes, achieving optical intensity modulation. After passing through the true-delay beamforming network, the signal is converted to an electrical signal via photoelectric conversion using a photodetector.

[0007] At present, the microwave communication technology used in traditional satellite communication technology has problems such as severe bandwidth shortage, weak anti-interference ability, and limited satellite system payload and information processing capabilities, and cannot meet the growing communication needs. Summary of the Invention

[0008] In light of this, the present invention proposes a microwave photonic broadband direct-modulation multi-beamforming network system based on microwave photonic direct-modulation links and an optically controlled beamforming network. Based on microwave photonic direct-modulation links and an optically controlled beamforming network, the present invention improves the system's operating frequency band and instantaneous operating bandwidth, and enables either split-beam or combined-beam modes depending on the application, achieving high-speed, high-capacity, flexible, and reliable transmission for the application system.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is:

[0010] A microwave photon broadband direct modulation multi-beam forming network system includes a direct modulation transmission module, an optical delay attenuation module, a photoelectric conversion module, a beam reconstruction module, and a beam control module. The photoelectric conversion module includes an optical wavelength division multiplexer, an optical amplifier, and a photodetector connected in sequence. The direct modulation transmission module includes 2n electro-optical direct modulation paths. The optical delay attenuation module includes 2n delay attenuation control paths, where n is greater than or equal to 1. The 2n electro-optical direct modulation paths and the 2n delay attenuation control paths are connected in a one-to-one correspondence. The outputs of the 2n delay attenuation control paths are all connected to the optical wavelength division multiplexer.

[0011] The electro-optical direct modulation path includes a low-noise amplifier and a directly modulated laser connected in sequence. In the i-th electro-optical direct modulation path, the low-noise amplifier amplifies the input signal, and the amplified signal is modulated onto an optical carrier by the directly modulated laser, where i = 1, 2, ..., 2n.

[0012] The delay and attenuation control path includes an optical delay line and an optical attenuator connected in sequence; the i-th delay and attenuation control path receives the optical signal output by the i-th electro-optical direct modulation path, delays the optical signal through the optical delay line, and then attenuates the optical signal through the optical attenuator;

[0013] The beam control module calculates the delay value of the optical delay line and the attenuation value of the optical attenuator according to the external input scanning angle, and controls the optical delay line and the optical attenuator to adjust to the corresponding delay value and attenuation value;

[0014] The optical signals output from the first to the nth delay attenuation control paths are combined by a first optical wavelength division multiplexer, the combined signal is amplified by a first optical amplifier, and the amplified optical signal is photoelectrically converted by a first photodetector to obtain a first output electrical signal; the first output electrical signal is selected into a beam splitting or beam combining mode by a first electrical switch;

[0015] The optical signals output from the n+1th to 2nth delay attenuation control paths are combined by a second optical wavelength division multiplexer, the combined signal is amplified by a second optical amplifier, and the amplified optical signal is photoelectrically converted by a second photodetector to obtain a second output electrical signal; the second output electrical signal is selected as a beam splitting or beam combining mode by a second electrical switch.

[0016] Furthermore, the input signals of the 2n electro-optical direct modulation paths have the same frequency and power, the frequency range is 2 to 18 GHz, and the power range is -60 dBm to -40 dBm.

[0017] Furthermore, the beam control module is used to calibrate the optical delay attenuation module, setting the optical delay line so that the delay of each path is equal, and setting the optical attenuator so that the attenuation value of each path is equal; wherein, the optical delay line is set so that the delay of each path is equal, and the specific method is:

[0018] First, calculate the delay value of each optical delay line according to the external input scanning angle:

[0019]

[0020] Where d is the antenna element spacing, θ is the scanning angle, c is the speed of light, and τ i is the delay value of the i-th optical delay line;

[0021] Then, each optical delay line is controlled to adjust to the corresponding delay value.

[0022] Furthermore, the delay value of the optical delay line ranges from 0 ps to 500 ps, ​​and the attenuation value of the optical attenuator ranges from 0 dB to 20 dB.

[0023] Furthermore, the wavelengths of the optical signals in the 1st to 2nth electro-optical direct modulation paths / delay attenuation control paths decrease by 0.8 nm in sequence.

[0024] The beneficial effects of the present invention are:

[0025] 1. The present invention utilizes direct-modulation optical links and optical beamforming networks to construct a broadband direct-modulation beamforming network system, which can increase the operating frequency band and instantaneous operating bandwidth, and provide a beamforming network for application systems such as communications, electronic warfare, and radar.

[0026] 2. The present invention can improve the operating frequency band and instantaneous operating bandwidth of the system, realize wide-bandwidth angle scanning, and realize beam splitting mode or beam combining mode according to the application situation, thereby achieving high-speed, large-capacity, flexible and reliable transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the structure of a microwave photonic broadband direct-modulation multi-beam forming network system in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] A microwave photon broadband direct-modulation multi-beam forming network system is disclosed. The system is based on a direct-modulation optical link and an optically controlled beam forming network. The system comprises a direct-modulation transmission module comprising 2n low-noise amplifiers and direct-modulation lasers, an optical delay attenuation module comprising 2n optical delay lines and an attenuation module, two sets of photoelectric conversion modules comprising a wavelength division multiplexer, an optical amplifier and a photodetector, a beam reconstruction module comprising an electric switch and a power divider, and a control module, thereby constructing a microwave photon broadband direct-modulation multi-beam forming network system.

[0030] Specifically, if Figure 1 As shown, it includes a direct modulation transmission module, an optical delay attenuation module, an optoelectronic conversion module, a beam reconstruction module and a beam control module (not shown).

[0031] The direct-modulation transceiver module includes a first low-noise amplifier, a first direct-modulation laser, a second low-noise amplifier, a second direct-modulation laser, a third low-noise amplifier, a third direct-modulation laser, a fourth low-noise amplifier, a fourth direct-modulation laser, a fifth low-noise amplifier, a fifth direct-modulation laser, a sixth low-noise amplifier, a sixth direct-modulation laser, a seventh low-noise amplifier, a seventh direct-modulation laser, an eighth low-noise amplifier, and an eighth direct-modulation laser.

[0032] The optical delay attenuation module includes a first optical delay line, a first optical attenuator, a second optical delay line, a second optical attenuator, a third optical delay line, a third optical attenuator, a fourth optical delay line, a fourth optical attenuator, a fifth optical delay line, a fifth optical attenuator, a sixth optical delay line, a sixth optical attenuator, a seventh optical delay line, a seventh optical attenuator, an eighth optical delay line, and an eighth optical attenuator.

[0033] The photoelectric conversion module includes an optical wavelength division multiplexer 1 , an optical amplifier 1 , a photodetector 1 , an optical wavelength division multiplexer 2 , an optical amplifier 2 and a photodetector 2 .

[0034] The beam reconstruction module includes an electrical switch 1, an electrical switch 2 and a power divider.

[0035] In the direct modulation transceiver module, the frequency of the first input signal is f 1入 , power P 1入， The first low noise amplifier amplifies the gain of the first input signal, and the amplified signal is modulated onto the optical carrier through the first direct-modulated laser. The wavelength of the optical carrier is 1552.52nm. The frequency of the second input signal is f 2入 Power P 2入， The second low noise amplifier amplifies the gain of the second input signal, and the amplified signal is modulated onto the optical carrier through the second direct-modulated laser. The wavelength of the optical carrier is 1551.72nm. The frequency of the third input signal is f 3入 , power P 3入， The third low noise amplifier performs gain amplification on the third input signal, and the amplified signal is modulated onto an optical carrier through a third direct-modulated laser. The wavelength of the optical carrier is 1550.92nm. The frequency of the fourth input signal is f 4入 , power P 4入， The fourth low noise amplifier amplifies the fourth input signal, and the amplified signal is modulated onto an optical carrier through a fourth direct-modulated laser. The wavelength of the optical carrier is 1550.12nm. The frequency of the fifth input signal is f 5入 Power P 5入， The fifth low noise amplifier amplifies the fifth input signal, and the amplified signal is modulated onto an optical carrier through the fifth direct-modulated laser. The wavelength of the optical carrier is 1549.32nm. The frequency of the sixth input signal is f 6入 , power P 6入， The sixth low noise amplifier amplifies the sixth input signal, and the amplified signal is modulated onto an optical carrier through the sixth direct-modulated laser. The wavelength of the optical carrier is 1548.51nm. The frequency of the seventh input signal is f 7入 , power P 7入， The seventh low noise amplifier amplifies the seventh input signal, and the amplified signal is modulated onto the optical carrier through the seventh direct-modulated laser. The wavelength of the optical carrier is 1547.72nm. The frequency of the eighth input signal is f 8入 , power P 8入， The eighth low noise amplifier performs gain amplification on the eighth input signal, and the amplified signal is modulated onto an optical carrier through an eighth directly modulated laser, and the wavelength of the optical carrier is 1546.92 nm.

[0036] In the optical delay attenuation module, the first input optical signal has an optical carrier wavelength of 1552.52nm, which is delayed by the first optical delay line and then attenuated by the first attenuator. The second input optical signal has an optical carrier wavelength of 1551.72nm, which is delayed by the second optical delay line and then attenuated by the second attenuator. The third input optical signal has an optical carrier wavelength of 1550.92nm, which is delayed by the third optical delay line and then attenuated by the third attenuator. The fourth input optical signal has an optical carrier wavelength of 1550.12nm, which is delayed by the fourth optical delay line and then attenuated by the fourth attenuator. Attenuation is performed. The optical carrier wavelength of the fifth input optical signal is 1549.32nm. It is delayed by the fifth optical delay line and then attenuated by the fifth attenuator. The optical carrier wavelength of the sixth input optical signal is 1548.51nm. It is delayed by the sixth optical delay line and then attenuated by the sixth attenuator. The optical carrier wavelength of the seventh input optical signal is 1547.72nm. It is delayed by the seventh optical delay line and then attenuated by the seventh attenuator. The optical carrier wavelength of the eighth input optical signal is 1546.92nm. It is delayed by the eighth optical delay line and then attenuated by the eighth attenuator.

[0037] In the photoelectric conversion module, the first four optical signals that have undergone optical delay and optical attenuation are combined through the optical wavelength division multiplexer 1. The wavelength of the first channel of the wavelength division multiplexer is 1552.52nm, the wavelength of the second channel is 1551.72nm, the wavelength of the third channel is 1550.92nm, and the wavelength of the fourth channel is 1550.12nm. The combined signal is amplified by the optical amplifier 1. The amplified optical signal is photoelectrically converted by the photodetector 1 to obtain the output electrical signal 1 with a frequency of f 出1 , power is P 出1

[0038] The last four optical signals that have undergone optical delay and optical attenuation are combined by optical wavelength division multiplexer 2. The wavelength of the fifth channel is 1549.32nm, the wavelength of the sixth channel is 1548.51nm, the wavelength of the seventh channel is 1547.72nm, and the wavelength of the eighth channel is 1546.92nm. The combined signal is amplified by optical amplifier 2. The amplified optical signal is converted into an output electrical signal 2 by photoelectric detector 2 with a frequency of f 出2 , power is P 出2 .

[0039] In the beam reconstruction module, electrical signal 1 passes through electrical switch 1 and can be output to sub-beam 1 or transmitted to a power splitter according to control. Electrical signal 2 passes through electrical switch 2 and can be output to sub-beam 2 or transmitted to a power splitter according to control. The power splitter outputs the combined beam.

[0040] In the direct modulation transceiver module, f 1入 、f2入 、f 3入 、f 4入 、f 5入 、f 6入 、f 7入 、f 8入 The setting range is 2~18GHz, and f 1入 =f 2入 =f 3入 =f 4入 =f 5入 =f 6入 =f 7入 =f 8入 .P 1入 、P 2入 、P 3入 、P 4入 、P 5入 、P 6入 、P 7入 、P 8入 The setting range is -60dBm~-40dBm, and P 1入 =P 2入 =P 3入 =P 4入 =P 5入 =P 6入 =P 7入 =P 8入 .

[0041] The control module first calibrates the delay attenuation module, sets the optical delay line so that the delay of each path is equal, that is, τ1 = τ2 = τ3 = τ4 = τ5 = τ6 = τ7 = τ8, and sets the optical attenuator so that the attenuation value of each path is equal, that is, A1 = A2 = A3 = A4 = A5 = A6 = A7 = A8.

[0042] The method for setting the optical delay line so that the delay of each path is equal is as follows:

[0043] First, calculate the delay value of the optical delay line according to the external input scanning angle:

[0044]

[0045] Where d is the antenna element spacing, θ is the scanning angle, and c is the speed of light.

[0046] Then, each optical delay line is controlled to be adjusted to a corresponding delay value simultaneously.

[0047] The optical delay value of the optical delay line can be set in the range of 0ps to 500ps, which can meet the scanning angle of ±45°. The optical attenuation value of the optical attenuator can be set in the range of 0dB to 20dB.

[0048] In the photoelectric conversion module, the output signal frequency f is generated 出=f 1入 =f 2入 =f 3入 =f 4入 =f 5入 =f 6入 =f 7入 =f 8入 , power P 出 =P 1入 +A1, A1 must be greater than 30dB.

[0049] The working principle of the present invention is as follows:

[0050] First, the 8 input electrical signals are amplified and modulated onto optical carriers of different wavelengths through the direct modulation transceiver module. The first wavelength is 1552.52nm, the second wavelength is 1551.72nm, the third wavelength is 1550.92nm, the fourth wavelength is 1550.12nm, the fifth wavelength is 1549.32nm, the sixth wavelength is 1548.51nm, the seventh wavelength is 1547.72nm, and the eighth wavelength is 1546.92nm.

[0051] Then, the optical signal modulated into the optical carrier passes through the optical delay attenuation module, and the 8-way optical delay line and optical attenuation value are adjusted according to the scanning angle.

[0052] Finally, the modulated optical signal is divided into two beams through the optoelectronic conversion module and combined, and optical amplification and optoelectronic detection are performed to obtain an electrical signal. The signal is then controlled to a split beam mode or a combined beam mode according to the electrical switch to complete the direct modulation beam forming.

[0053] The directly modulated multi-beamforming network constructed by the present invention can achieve an operating frequency band of 2 to 18 GHz, an instantaneous operating bandwidth of 500 MHz, a gain of 30 dB, a noise figure of 4.5, and a scanning angle of ±45°. By utilizing directly modulated links, the performance is improved while avoiding the use of expensive modulators, thus saving costs.

[0054] In summary, the present invention constructs a broadband direct-modulation multi-beamforming network system based on optical devices such as direct-modulation links and optical delay lines, which can improve the operating frequency band and instantaneous operating bandwidth, and provide beamforming network technology support for application systems such as communications, electronic warfare, and radar.

[0055] The above description is only a specific implementation of the present invention in the embodiment, but the scope of protection of the present invention is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with the field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A microwave photonic broadband direct modulation multi-beam forming network system, characterized in that: The optical transmission system comprises a direct modulation transmission module, an optical delay attenuation module, an optoelectronic conversion module, a beam reconstruction module, and a beam control module. The optoelectronic conversion module comprises a first optical wavelength division multiplexer, a first optical amplifier, and a first photodetector connected in sequence, and a second optical wavelength division multiplexer, a second optical amplifier, and a second photodetector connected in sequence. The direct modulation transmission module comprises 2n-channel electro-optical direct modulation paths. The optical delay attenuation module comprises 2n-channel delay attenuation control paths, where n≥1. The 2n-channel electro-optical direct modulation paths and the 2n-channel delay attenuation control paths are connected in a one-to-one correspondence. The outputs of the 1st to nth delay attenuation control paths are all connected to the first optical wavelength division multiplexer, and the outputs of the n+1th to 2nth delay attenuation control paths are all connected to the second optical wavelength division multiplexer. The beam reconstruction module comprises a first electrical switch, a second electrical switch, and a power splitter. The electro-optical direct modulation path includes a low-noise amplifier and a directly modulated laser connected in sequence. In the i-th electro-optical direct modulation path, the low-noise amplifier amplifies the input signal, and the amplified signal is modulated onto an optical carrier by the directly modulated laser, where i = 1, 2, ..., 2n. The delay and attenuation control path includes an optical delay line and an optical attenuator connected in sequence; the i-th delay and attenuation control path receives the optical signal output by the i-th electro-optical direct modulation path, delays the optical signal through the optical delay line, and then attenuates the optical signal through the optical attenuator; The beam control module calculates the delay value of the optical delay line and the attenuation value of the optical attenuator according to the external input scanning angle, and controls the optical delay line and the optical attenuator to adjust to the corresponding delay value and attenuation value; The optical signals output from the first to the nth delay attenuation control paths are combined by a first optical wavelength division multiplexer, the combined signal is amplified by a first optical amplifier, and the amplified optical signal is photoelectrically converted by a first photodetector to obtain a first output electrical signal. The first output electrical signal is selected into a beam splitting or beam combining mode by a first electrical switch. The optical signals output from the (n+1)th to (2n)th delay attenuation control paths are combined by a second optical wavelength division multiplexer, the combined signal is amplified by a second optical amplifier, and the amplified optical signal is photoelectrically converted by a second photodetector to obtain a second output electrical signal. The second output electrical signal is selected into a beam splitting mode or a beam combining mode through a second electrical switch.

2. The microwave photonic broadband directly modulated multi-beam forming network system according to claim 1, characterized in that: The input signals of the 2n electro-optical direct modulation channels have the same frequency and power, the frequency range is 2 to 18 GHz, and the power range is -60 dBm to -40 dBm.

3. The microwave photonic broadband directly modulated multi-beam forming network system according to claim 1, characterized in that: The beam control module is used to calibrate the optical delay attenuation module. The optical delay line is set to make the delay of each path equal, and the optical attenuator is set to make the attenuation value of each path equal. The specific method of setting the optical delay line to make the delay of each path equal is as follows: First, calculate the delay value of each optical delay line according to the external input scanning angle: Where d is the antenna element spacing, θ is the scanning angle, c is the speed of light, and τ i is the delay value of the i-th optical delay line; Then, each optical delay line is controlled to adjust to the corresponding delay value.

4. The microwave photonic broadband directly modulated multi-beam forming network system according to claim 1, characterized in that: The delay value of the optical delay line ranges from 0ps to 500ps, and the attenuation value of the optical attenuator ranges from 0dB to 20dB.

5. The microwave photonic broadband directly modulated multi-beam forming network system according to claim 1, characterized in that: The wavelengths of the optical signals in the 1st to 2nth electro-optical direct modulation paths decrease by 0.8 nm in sequence, and the wavelengths of the optical signals in the 1st to 2nth delay attenuation control paths decrease by 0.8 nm in sequence.

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