Microwave photon broadband direct modulation multi-beam forming network system

Abstract

The invention provides a microwave photon broadband direct modulation multi-beam forming network system, and relates to the fields of microwave photonics, true time delay beam forming, broadband multi-beam forming and the like. The device comprises a direct modulation transmitting module, an optical delay attenuation module, a photoelectric conversion module, a beam reconstruction module and a beam control module, the photoelectric conversion module comprises an optical wavelength division multiplexer, an optical amplifier and a photoelectric detector, the direct modulation transmitting module comprises 2n electro-optical direct modulation paths, and the optical delay attenuation module comprises 2n delay attenuation control paths, the 2n electro-optical direct modulation paths and the 2n delay attenuation control paths are connected in a one-to-one correspondence mode, and the outputs of the 2n delay attenuation control paths are all connected with the optical wavelength division multiplexer. Based on the microwave photon direct modulation link and the light-operated beam forming network, the working frequency band and the instantaneous working bandwidth of the system can be improved, wide-angle scanning, ultra wide band and a beam splitting mode or a beam combining mode are achieved at the same time, and high-speed, large-capacity and reliable transmission of an application system is guaranteed.

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 in particular relates to a microwave photonic broadband direct modulation multi-beamforming network system. Background Art

[0002] In the fields of satellite communications, radar, electronic warfare, etc., beamforming is a widely used array signal processing technology. 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 expected target and the null is aligned with the interference signal.

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

[0004] The phased array that uses an optical true time-delay phase-shift network based on microwave photonics to replace the traditional electrical phase-shift network is called an optically controlled phase-shift array. Since the RF signal is time-delayed in the optical domain after optical conversion, the optical true time-delay phase-shift network inherits the advantages of both microwave and photonic technologies and has many advantages over traditional electrical phase shifting, as follows:

[0005] First, the bandwidth of the phased array is expanded. Since the optical phase-shifting network realizes the true delay of the electrical signal, the system eliminates the beam deflection phenomenon and the aperture transit time, and can achieve a larger instantaneous bandwidth. In addition, since microwave photonic devices usually have a larger bandwidth, microwave signals do not need to be down-converted and can be directly synthesized in the optical domain. Secondly, the signal transmission loss is reduced. The loss of optical signals in optical fiber is extremely low. The optical transmission loss of 1550nm laser is generally 0.2dB / km, which is equivalent to 0.4dB / km of electrical signal loss, which is almost negligible compared to the loss of coaxial cable or waveguide. At the same time, since the frequency of microwave signals is much smaller than the frequency of light waves, the loss consistency of RF signals of different frequencies in optical fiber is very good. Third, the weight and volume of the system are reduced. The weight of optical fiber is usually 1.7kg / km, while the weight of coaxial cable is about 567kg / km. Using optical fiber to achieve delay will greatly reduce the weight of the system. In addition, quartz optical fiber has a smaller cross-sectional diameter and a smaller bending radius than coaxial cable, so the volume of the system can be further reduced. Fourth, anti-electromagnetic interference. Since microwave signals are transmitted through optical fibers on optical carriers, they are not interfered by external electromagnetic radiation during transmission, and do not generate electromagnetic radiation.

[0006] Direct modulation microwave photonic links have the advantages of simple structure, low cost, and easy implementation, so they are very suitable for large-scale beamforming networks. Direct modulation is to modulate the RF signal directly onto the optical carrier by directly modulating the laser, and to change the intensity of the output light wave by changing the driving current of the laser to achieve light intensity modulation. After passing through the true delay beamforming network, it is converted into an electrical signal through photoelectric conversion by 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 view of this, the present invention proposes a microwave photon broadband direct modulation multi-beam forming network system based on a microwave photon direct modulation link and an optically controlled beam forming network. The present invention is based on a microwave photon direct modulation link and an optically controlled beam forming network, which can improve the operating frequency band and instantaneous operating bandwidth of the system, and can realize a split beam mode or a combined beam mode according to the application situation, so as to realize high-speed, large-capacity, flexible and reliable transmission of 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 comprises a direct modulation transmission module, an optical delay attenuation module, an optoelectronic conversion module, a beam reconstruction module and a beam control module, wherein the optoelectronic conversion module comprises an optical wavelength division multiplexer, an optical amplifier and a photodetector connected in sequence, the direct modulation transmission module comprises 2n electro-optical direct modulation paths, the optical delay attenuation module comprises 2n delay attenuation control paths, n≥1, the 2n electro-optical direct modulation paths and the 2n delay attenuation control paths are connected in a one-to-one correspondence, and 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 direct modulation 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 through the direct modulation laser, i=1,2,...,2n;

[0012] The delay attenuation control path includes an optical delay line and an optical attenuator connected in sequence; the i-th delay 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 1st to the nth delay attenuation control paths are combined by the first optical wavelength division multiplexer, the combined signal is amplified by the first optical amplifier, the amplified optical signal is photoelectrically converted by the first photodetector to obtain a first output electrical signal; the first output electrical signal is selected as a beam splitting or beam combining mode by the first electrical switch;

[0015] The optical signals output from the n+1th to 2nth delay attenuation control paths are combined by the second optical wavelength division multiplexer, the combined signal is amplified by the second optical amplifier, the amplified optical signal is photoelectrically converted by the 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 the second electrical switch.

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

[0017] Further, the beam control module is used to calibrate the optical delay attenuation module, set the optical delay line so that the delay of each path is equal, and set 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, the delay value of each optical delay line is calculated 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 a 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 improve the working frequency band and instantaneous working 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 angular scanning, and can realize split-beam mode or combined-beam mode according to the application situation, thereby realizing 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 in conjunction with the accompanying drawings and specific implementation methods.

[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, and comprises a direct modulation transmitting module including 2n low noise amplifiers and direct modulation lasers, an optical delay attenuation module including 2n optical delay lines and an attenuation module, two sets of photoelectric conversion modules including a wavelength division multiplexer, an optical amplifier and a photoelectric detector, a beam reconstruction module including an electric switch and a power divider, and a control module, so as to construct 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 electric switch 1, an electric 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 performs gain amplification on the first input signal, and the amplified signal is modulated onto an optical carrier through the first direct-modulated laser, and 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 performs gain amplification on the second input signal, and the amplified signal is modulated onto an optical carrier through a second direct modulation laser, and 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, and 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 performs gain amplification on the fourth input signal, and the amplified signal is modulated onto an optical carrier through a fourth direct-modulated laser, and 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 performs gain amplification on the fifth input signal, and the amplified signal is modulated onto an optical carrier through the fifth direct-modulated laser, and 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 performs gain amplification on the sixth input signal, and the amplified signal is modulated onto an optical carrier through the sixth direct modulation laser, and 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 performs gain amplification on the seventh input signal, and the amplified signal is modulated onto an optical carrier through the seventh direct modulation laser, and 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 direct-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. The fifth input optical signal has an optical carrier wavelength of 1549.32nm, which is delayed by the fifth optical delay line and then attenuated by the fifth attenuator. The sixth input optical signal has an optical carrier wavelength of 1548.51nm, which is delayed by the sixth optical delay line and then attenuated by the sixth attenuator. The seventh input optical signal has an optical carrier wavelength of 1547.72nm, which is delayed by the seventh optical delay line and then attenuated by the seventh attenuator. The eighth input optical signal has an optical carrier wavelength of 1546.92nm, which 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 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 optical amplifier 1. The amplified optical signal is photoelectrically converted by photoelectric detector 1 to obtain output electrical signal 1 with a frequency of f 出1 , power is P 出1

[0038] The last 4 optical signals after optical delay and optical attenuation are combined through 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, and the frequency is 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 the power divider according to control. Electrical signal 2 passes through electrical switch 2 and can be output to sub-beam 2 or transmitted to the power divider according to control. The power divider outputs a 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 of 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 should be greater than 30dB.

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

[0050] First, through the direct modulation transceiver module, the 8 input electrical signals are amplified and modulated onto optical carriers of different wavelengths. 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 to the optical carrier passes through the optical delay attenuation module, and the 8 optical delay lines and optical attenuation values ​​are adjusted according to the scanning angle.

[0052] Finally, the regulated optical signal is divided into two beams through the optoelectronic conversion module for combination, and optical amplification and optoelectronic detection are performed to obtain an electrical signal, which is then controlled to a beam splitting mode or a beam combining mode according to the electrical switch to complete the direct modulation beam forming.

[0053] The direct modulation 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 a direct modulation link, the performance is improved while avoiding the use of expensive modulators, thereby 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 working frequency band and instantaneous working 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 protection scope of the present invention is not limited thereto. Any changes or substitutions 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 within the protection scope of the present invention.

Claims

1. A microwave photon broadband direct modulation multi-beam forming network system, characterized in that: 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. The optoelectronic 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. n≥1. The 2n electro-optical direct modulation paths and the 2n delay attenuation control paths are connected one by one. The outputs of the 2n delay attenuation control paths are all connected to the optical wavelength division multiplexer. The electro-optical direct modulation path includes a low noise amplifier and a direct modulation 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 through the direct modulation laser, i=1,2,...,2n; The delay attenuation control path includes an optical delay line and an optical attenuator connected in sequence; the i-th delay 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 1st to the nth delay attenuation control paths are combined by the first optical wavelength division multiplexer, the combined signal is amplified by the first optical amplifier, the amplified optical signal is photoelectrically converted by the first photodetector to obtain a first output electrical signal; the first output electrical signal is selected as a beam splitting or beam combining mode by the first electrical switch; 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 signals are amplified by a second optical amplifier, and the amplified optical signals are 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 through a second electrical switch.

2. A microwave photonic broadband direct modulation multi-beam forming network system as claimed in claim 1, characterized in that: 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.

3. A microwave photonic broadband direct modulation multi-beam forming network system as claimed in claim 1, characterized in that: The beam control module is used to calibrate the optical delay attenuation module, set the optical delay line so that the delay of each path is equal, and set 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: First, the delay value of each optical delay line is calculated 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 a corresponding delay value.

4. A microwave photonic broadband direct modulation multi-beam forming network system as claimed in 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. A microwave photonic broadband direct modulation multi-beam forming network system as claimed in claim 1, characterized in that: 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.

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