A microwave photonic power equalizer and a microwave photonic power equalization method based on power monitoring and compensation.

Abstract

This invention discloses a microwave photonic power equalizer and a microwave photonic power equalization method based on power monitoring and compensation. The equalizer includes a light source, a carrier-suppressed double-sideband modulation module, an optical power control module, a data processing and driving module, an optical power detection module, and a photodetector. The light source is split into two paths via an optical coupler: one path inputs to the carrier-suppressed double-sideband modulation module, and the other path inputs to the optical power control module. The carrier-suppressed double-sideband modulation module also outputs a channel to the optical power detection module. This invention provides a microwave photonic power equalizer and a microwave photonic power equalization method based on power monitoring and compensation. It enables power equalization of broadband microwave signals in the optical domain, without being limited by the frequency and bandwidth of electronic devices. Power equalization can be performed in real time based on changes in the power of the input signal simply by changing the power of the optical carrier through the optical power control module. Furthermore, all components used can be integrated, achieving miniaturization.

Description

Technical Field

[0001] This invention relates to power equalizers and power equalization methods, and more particularly to a microwave photonic power equalizer and microwave photonic power equalization method based on power monitoring and compensation. Background Technology

[0002] With the development of modern radar electronics technology, small, lightweight, highly reliable, and wide-bandwidth microwave components are widely used in aerospace and remote sensing fields. In synthetic aperture radar (SAR) systems, the bandwidth of the radar receiver has a significant impact on the system bandwidth; the larger the signal bandwidth, the higher the ground resolution of the radar image. Due to various factors, such as amplifier gain unevenness and power attenuation caused by mixing and filtering of low-frequency signal sources, wide bandwidth often degrades the receiver's amplitude-frequency characteristics, resulting in high low-frequency power and low high-frequency power, thus damaging the flatness of the output signal within the band. Amplitude-frequency errors in the receiving system can cause a deterioration in the main lobe broadening and integral sidelobe ratio of the pulse compression output of the SAR system, and may even lead to the appearance of false targets. Power equalizers play a crucial role in broadband radar receivers; they provide a corresponding attenuation curve to compensate for gain fluctuations within the operating frequency band, obtaining flat output power and thus improving the system's amplitude-frequency characteristics.

[0003] At present, microwave power equalizers are mainly implemented using traditional electronic technologies, mainly including three types: lumped parameter type, waveguide type, coaxial type, and microstrip line type. Extensive research has been conducted on implementing microwave power equalization using these four methods, including a design method for compensating for the decreasing gain equalizer within the operating frequency band. This method uses theoretical analysis to set the initial values, uses computer optimization to determine the equalizer structure, and realizes the miniaturization requirements through the microstrip serpentine line structure. A miniaturized power equalizer in the L band was designed (Zheng Xiaoyu, Jian Chunxiao, Liu Luokun, Zhang Honggang. Research on the Design of Microstrip Power Equalizer [J]. Radar Science and Technology, 2015, 13(05): 543-548.), and from the perspective of engineering practice, a resistively loaded resonant network was given to form an X-band power equalizer. An input / output T-junction impedance matching device was added, and at the same time, the influence of the high-frequency distribution parameters of the microstrip line and lumped devices was fully considered to improve the input / output standing wave ratio and reduce the insertion loss at the high end of the equalizer (Li Jian, Li Yongli, Xiao Dengjun. Design and Implementation of an X-Band Broadband Low-Loss Power Equalizer [J]. Modern Radar, 2011, 33(03): 67-69+72.), etc. The first three methods are realized by changing the parameters of the resonant cavity, and there are problems such as large volume, complex structure, and poor stability. The fourth method is realized by forming an equalization circuit on the microstrip line, with small volume, light weight, and good stability. However, since the resistor is directly loaded on the main transmission line, the reflection of the circuit is greatly enhanced, which not only increases the input / output standing wave ratio of the system but also introduces a large high-end insertion loss. The microwave power equalizers designed by the above four methods all have the problem of fixed parameters and cannot cope with different gain fluctuations, and are limited by the electronic bottleneck, with limited ability to handle high-frequency and wide-bandwidth power equalization.

[0004] Therefore, in order to solve the problems of large volume, complex structure, and large standing wave ratio existing in microwave power equalizers designed by traditional electronic technologies, break through the bottleneck of low operating frequency and small bandwidth of power equalizers in the electronic field, and the problem of being unable to adapt to input signals with different power flatness, it is extremely important to adopt a structure based on microwave photon technology to overcome the above problems for the development of fields such as radar detection, wireless communication, and sensing. Summary of the Invention

[0005] The purpose of the present invention is to provide a microwave photon power equalizer and a microwave photon power equalization method based on power monitoring and compensation to solve the problems raised in the above background technology.

[0006] To achieve the above purpose, the present invention provides the following technical solution: A microwave photon power equalizer and a microwave photon power equalization method based on power monitoring and compensation, including a light source, a carrier suppression double-sideband modulation module, an optical power control module, a data processing and driving module, an optical power detection module, and a photodetector;

[0007] The light source is divided into two paths through an optical coupler. One path is input into the carrier-suppressed double-sideband modulation module, and the other path is input into the optical power control module. One branch of the carrier-suppressed double-sideband modulation module is input into one channel of the optical power detection module, and the other branch is coupled with the optical carrier after optical power control into one path. The coupled optical signal is further divided into two paths. One path is input into the other channel of the optical power detection module, and the other path is input into a photodetector for photoelectric conversion. The output data of the optical power detection module is input into the data processing and driving module, and then the optical power control module is driven according to the result to change the optical carrier power.

[0008] As a preferred technical solution of the present invention, the microwave signal to be equalized is a broadband signal corresponding to one frequency at a time, such as a chirp signal, a frequency-hopping signal, etc.

[0009] As a preferred technical solution of the present invention, the carrier-suppressed double-sideband modulation module is a Mach-Zehnder modulator or a phase modulator cascaded with an optical band-stop filter.

[0010] As a preferred technical solution of the present invention, the optical power detection module is a dual-channel optical power meter, which can simultaneously monitor the optical power before equalization and the optical power after equalization.

[0011] As a preferred technical solution of the present invention, the data processing and driving module is triggered by the synchronization signal of the microwave signal to be equalized.

[0012] As a preferred technical solution of the present invention, the optical power control module is an electrically controlled variable optical attenuator.

[0013] As a preferred technical solution of the present invention, it includes the following steps:

[0014] S1: The light source generates an optical carrier and is divided into two paths. One path is input into the carrier-suppressed double-sideband modulation module, and the other path is for power control.

[0015] S2: The carrier-suppressed double-sideband modulation module is used to modulate the microwave signal to be equalized onto the optical carrier to generate a carrier-suppressed double-sideband modulation optical signal.

[0016] S3: The output of the carrier-suppressed double-sideband modulator module is divided into two paths. One path is input into the optical power detection module, and the other path is coupled with the optical carrier after power control. The coupled optical signal is further divided into two paths. One path is input into the optical power detection module, and the other path is subjected to photoelectric conversion through a photodetector to output the equalized microwave signal.

[0017] As a preferred technical solution of the present invention, the optical power-time data obtained by the optical power detection module is processed and feedback compensation is made to drive the optical power control module to change the optical power value at each moment; at the same time, error analysis is performed on the equalized carrier-suppressed double-sideband optical signal and the optical power coupled from the optical carrier to determine whether equalization is needed again.

[0018] As a preferred technical solution of the present invention, when one of the channels of the optical power detection module scans out the value of the modulator output optical power changing with time after loading the broadband signal to be equalized, it is recorded as P1(t).

[0019] As a preferred embodiment of the present invention, the data processing and driving module drives the optical power control module to change the optical carrier power value at each moment according to P2(t) based on the collected optical power change value P1(t). The relationship between P1(t) and P2(t) is as follows:

[0020] P1(t) + P2(t) = C

[0021] Where C is a constant.

[0022] As a preferred technical solution of the present invention, the output optical power of the other channel of the optical power detection module after the equalization of the carrier suppression double-sideband modulation module and the optical power control module is scanned and denoted as P3(t). This is used to judge the equalization effect. When P3(t)-C<=▽ (▽ is the defined minimum error value), the equalization is judged to be completed. If it is not satisfied, the equalization is performed again.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: The microwave photonic power equalizer and microwave photonic power equalization method based on power monitoring and compensation of the present invention can perform power equalization of broadband microwave signals in the optical domain, without being limited by the frequency and bandwidth of electronic devices. Power equalization can be performed in real time according to the power change of the input signal simply by changing the power of the optical carrier through the optical power control module. Moreover, all the devices used can be integrated to achieve miniaturization. Attached Figure Description

[0024] Figure 1 This is a structural block diagram of a microwave photonic power equalizer based on power monitoring and compensation according to the present invention.

[0025] Figure 2 This is a flowchart of the power monitoring and compensation method of the present invention;

[0026] Figure 3 This is a structural block diagram of a microwave photonic power equalizer based on a Mach-Zehnder modulator in one embodiment of the present invention;

[0027] Figure 4This is a schematic diagram of the time variation of the optical power curve in one embodiment of the present invention. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention have been clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Please see Figure 1-4 This invention provides a microwave photonic power equalizer and a microwave photonic power equalization method based on power monitoring and compensation, comprising a light source, a carrier-suppressed double-sideband modulation module, an optical power control module, a data processing and driving module, an optical power detection module, and a photodetector. The light source is split into two paths by an optical coupler: one path is input to the carrier-suppressed double-sideband modulation module, and the other path is input to the optical power control module. The output of the carrier-suppressed double-sideband modulation module is split into one channel input to the optical power detection module, and the other path is coupled to the optical carrier after optical power control. The coupled optical signal is then split into another channel input to the optical power detection module, and the other path is input to the photodetector for photoelectric conversion. The output data of the optical power detection module is input to the data processing and driving module, which then drives the optical power control module to change the optical carrier power based on the result.

[0030] The specific functions of each module are as follows:

[0031] The light source is used to generate an optical carrier wave, which is divided into two paths: one path modulates the microwave signal to be equalized, and the other path performs power control.

[0032] The carrier-suppressed double-sideband modulation module is used to modulate the microwave signal to be equalized onto the optical carrier and to achieve carrier-suppressed double-sideband modulation.

[0033] Optical power control module, used to control the power of optical carrier;

[0034] The optical power monitoring module is used to simultaneously monitor the optical power before and after equalization.

[0035] The data processing and driving module is used to process and analyze optical power monitoring data, and drive the optical power control module based on the results.

[0036] A photodetector is used to convert equalized optical signals into electrical signals.

[0037] Furthermore, the carrier-suppressed double-sideband modulation module can be implemented in various existing or future ways, such as using a Mach-Zehnder modulator or using a phase modulator plus an optical bandstop filter.

[0038] Based on the above microwave photon power equalizer based on power monitoring and compensation, the present invention also provides a power equalization method, including the following steps:

[0039] S1: The light source generates an optical carrier and divides it into two paths. One path is input into the carrier-suppressed double-sideband modulation module, and the other path is for power control.

[0040] S2: The carrier-suppressed double-sideband modulation module is used to modulate the microwave signal to be equalized onto the optical carrier to generate a carrier-suppressed double-sideband modulated optical signal.

[0041] S3: The output of the carrier-suppressed double-sideband modulator module is divided into two paths. One path is input into the optical power detection module, and the other path is coupled with the optical carrier after power control. The coupled optical signal is further divided into two paths. One path is input into the optical power detection module, and the other path undergoes photoelectric conversion through a photodetector to output the equalized microwave signal.

[0042] S4: The data processing and driving module and the optical power detection module are synchronized with the microwave signal. The optical power-time data obtained by the optical power detection module is processed and feedback compensation is made to drive the optical power control module to change the optical power value at each moment. At the same time, error analysis is performed on the optical power of the coupled carrier-suppressed double-sideband optical signal and the optical carrier after equalization to determine whether re-equalization is required.

[0043] When the value of the optical power output by the modulator after loading the broadband signal with time is scanned by one channel of the optical power detection module, it is recorded as P1(t). The data processing and driving module drives the optical power control module to change the optical carrier power value at each moment according to the collected optical power change value P1(t) output by the carrier-suppressed double-sideband modulation module. The relationship between P1(t) and P2(t) is:

[0044] P1(t) + P2(t) = C

[0045] where C is a constant.

[0046] The other channel of the optical power detection module scans the optical power output after coupling the carrier-suppressed double-sideband modulation module and the optical power control module after equalization, which is recorded as P3(t), and is used to judge the equalization effect. When P3(t) - C <= ▽ (▽ is the defined minimum error value), it is determined that the equalization is completed. If not, re-equalization is performed. The flow chart of the algorithm in the whole power equalization process is as Figure 2 shown.

[0047] The following is one embodiment of the present invention. This embodiment uses a Mach-Zehnder modulator and proposes a microwave photonic power equalizer based on power monitoring and compensation, which can perform power equalization on broadband microwave signals in the optical domain and convert them to electrical domain output.

[0048] like Figure 3 The diagram shown is a structural block diagram of the power equalizer in this embodiment, including:

[0049] The light source is used to generate an optical carrier wave, which is divided into two paths: one path modulates the microwave signal to be equalized, and the other path performs power control.

[0050] A Mach-Zehnder modulator is used to modulate the microwave signal to be equalized onto an optical carrier and adjust the bias voltage to achieve carrier-suppressed double-sideband modulation.

[0051] Optical power control module, used to control the power of optical carrier;

[0052] The optical power monitoring module is used to simultaneously monitor the optical power before and after equalization.

[0053] The data processing and driving module is used to process and analyze optical power monitoring data, and drive the optical power control module based on the results.

[0054] A photodetector is used to convert equalized optical signals into electrical signals.

[0055] The following is combined Figure 3 and Figure 4 The principle of the microwave power equalizer of the present invention will be explained and described in detail.

[0056] The light source is split into two paths by an optical coupler. One path is input to a Mach-Zehnder modulator to modulate the microwave signal to be equalized, achieving carrier-suppressed double-sideband modulation. The other path is input to the optical power control module. The output of the Mach-Zehnder modulator is split into one channel of the optical power detection module and the other path is coupled to the optical carrier after optical power control. The coupled optical signal is then split into another channel of the optical power detection module and another path is input to a photodetector for photoelectric conversion. The output data of the optical power detection module is input to the data processing and driving module, which drives the optical power control module to change the optical carrier power based on the result.

[0057] Now, assuming that the microwave signal to be equalized is modulated onto an optical carrier, the relationship between the optical power output of the carrier-suppressed double-sideband modulation module and time is P1(t), and its curve is as follows: Figure 4 As shown in (a), the data processing and driving module drives the optical power control module to change the optical power of the optical carrier according to P2(t) based on the value of P1(t) and the desired power constant C for equalization. The curve of P2(t) is shown in Figure 1. Figure 4As shown in (b), the carrier-suppressed double-sideband optical signal and the optical carrier signal are coupled into one channel, and the output optical power is denoted as P3(t), and its curve is shown in Figure 1. Figure 4 As shown in (c), the data processing and driving module calculates the difference between P3(t) and C. When P3(t) - C <= ▽ (▽ is the defined minimum error value), the equalization is considered complete. If the condition is not met, the equalization is performed again.

[0058] In summary, this invention constructs a microwave power equalizer using a light source, a carrier-suppressed double-sideband modulation module, an optical power control module, an optical power detection module, a data processing and driving module, and a photodetector. This equalizer is capable of power equalization of broadband microwave signals in the optical domain, without being limited by the frequency and bandwidth of electronic devices. Power equalization can be performed in real time according to the power changes of the input signal simply by changing the power of the optical carrier through the optical power control module. Moreover, all the components used can be integrated to achieve miniaturization.

[0059] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A microwave photonic power equalizer and a microwave photonic power equalization method based on power monitoring and compensation, comprising a light source, a carrier-suppressed double-sideband modulation module, an optical power control module, a data processing and driving module, an optical power detection module, and a photodetector; The light source is split into two paths by an optical coupler: one path is input to the carrier-suppressed double-sideband modulation module, and the other path is input to the optical power control module. The carrier-suppressed double-sideband modulation module outputs one path to one channel of the optical power detection module, and the other path is coupled to the optical carrier after optical power control. The coupled optical signal is then split into another path and input to the other channel of the optical power detection module, and the other path is input to the photodetector for photoelectric conversion. The output data of the optical power detection module is input to the data processing and driving module, which then drives the optical power control module to change the optical carrier power based on the result. The data processing and driving module is synchronized with the microwave signal, processes the optical power-time data obtained by the optical power detection module, and makes feedback compensation to drive the optical power control module to change the optical power value at each moment; at the same time, it performs error analysis on the equalized carrier-suppressed double-sideband optical signal and the optical power coupled from the optical carrier to determine whether it needs to be equalized again. When one channel of the optical power detection module scans and detects the change in modulator output optical power over time after loading the broadband signal to be equalized, it is recorded as follows: ; The data processing and driving module calculates the changes in optical power based on the acquired values. Drive the optical power control module according to Change the optical carrier power value at each moment. and The relationship is: ； in, C is a constant; The optical power detection module scans the output optical power of the coupled carrier-suppressed double-sideband modulation module and optical power control module through another channel, denoted as . Used to judge the equilibrium effect, when the following conditions are met. hour, The minimum error value is defined as the time to determine if the balancing is complete. If the minimum error value is not met, the balancing process is repeated.

2. The microwave photonic power equalizer based on power monitoring and compensation according to claim 1, characterized in that: The microwave signal to be equalized is a linear frequency modulated signal or a frequency hopping signal.

3. The microwave photonic power equalizer based on power monitoring and compensation according to claim 1, characterized in that: The carrier-suppressed double-sideband modulation module is a Mach-Zehnder modulator or a phase modulator of a cascaded optical bandstop filter.

4. The microwave photonic power equalizer based on power monitoring and compensation according to claim 1, characterized in that: The optical power detection module is a dual-channel optical power meter that can simultaneously monitor the optical power before and after equalization.

5. The microwave photonic power equalizer based on power monitoring and compensation according to claim 1, characterized in that: The data processing and driving module is triggered by the synchronization signal of the microwave signal to be equalized.

6. The microwave photonic power equalizer based on power monitoring and compensation according to claim 1, characterized in that: The optical power control module is an electrically adjustable optical attenuator.

7. A power equalization method using the power equalizer as described in claim 1, characterized in that, Includes the following steps: S1: The light source generates an optical carrier and splits it into two paths. One path is input to the carrier suppression double-sideband modulation module, and the other path is used for power control. S2: The carrier-suppressed double-sideband modulation module is used to modulate the microwave signal to be equalized onto the optical carrier to generate a carrier-suppressed double-sideband modulated optical signal. S3: The output of the carrier-suppressed double-sideband modulator module is divided into two paths. One path is input to the optical power detection module, and the other path is coupled to the optical carrier after power control. The coupled optical signal is then split into two paths and input to the optical power detection module. The other path is converted into a photoelectric signal by a photodetector and outputs a balanced microwave signal.

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