CN112217565B - Method for suppressing third-order and fifth-order intermodulation distortion of microwave photon down-conversion link - Google Patents

Method for suppressing third-order and fifth-order intermodulation distortion of microwave photon down-conversion link Download PDF

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CN112217565B
CN112217565B CN202010825635.0A CN202010825635A CN112217565B CN 112217565 B CN112217565 B CN 112217565B CN 202010825635 A CN202010825635 A CN 202010825635A CN 112217565 B CN112217565 B CN 112217565B
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张进
张钧凯
沃江海
王亚兰
王安乐
罗雄
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Air Force Early Warning Academy
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    • H04—ELECTRIC COMMUNICATION TECHNIQUE
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    • H04—ELECTRIC COMMUNICATION TECHNIQUE
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Abstract

The invention relates to a method for suppressing third-order and fifth-order intermodulation distortion of a microwave photon down-conversion link.A laser emits a light beam, and the light beam is output after being modulated by a local oscillator signal received by a third phase modulator, wherein the modulation of the third phase modulator is controlled by controlling the power of the local oscillator signal, the signal modulated by the third phase modulator is divided into a first light beam and a second light beam by a 3dB coupler, the first light beam is modulated by a first phase modulator, then is subjected to a first optical filter, and is output to a first input end of a balance detector after passing through the first optical filter, so that a first branch is formed; and the second light beam is output to the second phase modulator after passing through the optical attenuator, is output to the second optical filter after being modulated by the second phase modulator, and is output to the second input end of the balance detector after passing through the second optical filter to form a second branch.

Description

Method for suppressing third-order and fifth-order intermodulation distortion of microwave photon down-conversion link
Technical Field
The invention relates to the field of optical communication and the technical field of microwave photons, in particular to a method for inhibiting third-order and fifth-order intermodulation distortion of a microwave photon down-conversion link.
Background
The microwave photon technology is used for transmitting, processing and applying microwave signals by utilizing an optical technology, combines the advantages of the microwave technology fineness and the photon technology broadband, and is widely applied to a plurality of military and civil fields such as satellite communication, broadcast television, light-operated phased array antenna, navigation and the like. Microwave Photonic Links (MPL) are one of the important applications of microwave photonic technology. Because the microwave photon technology has the characteristics of wide working frequency band, large instantaneous bandwidth, light weight, small volume, electromagnetic interference resistance and the like, the radar system designed based on the MPL has unique advantages. The microwave photon frequency conversion link realizes frequency mixing of the electric signal and the local oscillator signal by modulating the electric signal and the local oscillator signal to an optical domain, the optical signal after frequency mixing is reduced into the electric signal through a photoelectric conversion device, and an up-down frequency conversion signal output by frequency mixing can be respectively used in a transmitter or a receiver of a radio frequency front end.
The spurious-free dynamic range (SFDR) is an important performance index for measuring the MPL down-conversion link, and is defined as the corresponding rf signal input power range under the condition that the output power is greater than the noise power and the input intermodulation distortion power is less than the noise power. Thus, intermodulation distortion determines the range of the link that is tolerant to high power rf inputs. Under the condition of inputting a two-tone signal, the frequency term of Third-order intermodulation distortion (IMD 3) generated by the nonlinearity of a modulator is very close to the fundamental frequency term in the frequency domain, and is difficult to be filtered by a filter directly, so that the first factor for limiting the link SFDR is provided. After the IMD3 is suppressed, Fifth-order intermodulation distortion (IMD 5) very close to the fundamental frequency term becomes a main limiting factor for further improving the link SFDR, but few studies report. Therefore, in order to further break through the upper limit of the down-conversion link SFDR, how to realize the suppression of IMD5 on the basis of the suppression of IMD3 is an unavoidable problem, and has very important research significance.
Currently, most research approaches achieve SFDR boost for wave photon down-conversion links based on the suppression of IMD 3. In the early days, there are typical Dual Wavelength Modulation structure, local oscillator power control or polarization state transmission control of Link, realizing IMD3 suppression and Link frequency conversion (Haas B M, multiplex T E. linear descending Photonic Link Using Dual-Wavelength Phase Modulation and Optical Filtering [ J ]. IEEE Photonic Journal,2011,3(1):1-12.Pagan V R, Haas B M, multiplex T E, et al. linear electronic Microwave down conversion and Optical Filtering [ J ]. Optic Express,2011,19(2):883-895.Li, N L, Zhou T, et al. image downlink polar Modulation and Optical Filtering [ J ]. Optical Phase Modulation, 19(2):883-895.Li, N L, Zhou T, et al. image gain downlink polar Modulation [ J ]. 2641 ] and I, J. Optical Modulation [ 9 ]. In addition, a large number of schemes for improving SFDR by digital signal processing have been proposed, but the basis for the schemes needs to be based on analog-to-digital conversion. However, most of them have complicated structure, and the schemes based on MZM or dual-drive MZM based on MZM, dual-parallel MZM or parallel dual-parallel MZM have disadvantages, because MZM needs to introduce a direct current signal to determine the operation state, which introduces the problem of bias point drift. (Cui Y, Dai Y, Yin F, et al. enhanced spectral-Free Dynamic Range in inductive-Modulated Analog Photonic Link Using Digital Postprocessing [ J ]. IEEE Photonic Journal of 2014,6(2):1-8.Pan Y, Yan L, Chen Z, et al. adaptive linear macroscopic Conversion a single dual-electrode Mach-Zehnder modulator [ J ]. Optics Letters, 201540 (11):2649-2652.Huang L, Li R, Chen D, et al. Photonic Downconverter of Signals, III, Mo. F. III. IV. III; on the other hand, there are few reports on how to achieve IMD5 inhibition after IMD3 inhibition.
Disclosure of Invention
Therefore, the invention provides a method for inhibiting third-order and fifth-order intermodulation distortion of a microwave photon down-conversion link, which not only adopts a phase modulator to avoid the problem of bias point drift, but also can solve the problem of simultaneously realizing IMD3 inhibition and IMD5 inhibition in the prior art.
In order to achieve the above object, the present invention provides a method for suppressing third-order and fifth-order intermodulation distortion of a microwave photonic downconversion link, wherein a laser generates a light beam, the light beam passes through a third phase modulator, the third phase modulator receives a local oscillation signal and modulates the local oscillation signal onto an optical signal in the light beam, the third phase modulator outputs the modulated light beam, the 3dB coupler divides the light beam modulated by the third phase modulator into a first light beam and a second light beam, the first light beam is output to the first phase modulator, the first phase modulator receives a first radio frequency signal emitted by a radio frequency signal and modulated by an electrical attenuator onto an optical signal in the first light beam, the first phase modulator outputs the modulated first light beam to a first optical filter, and the modulated first light beam is output to one end of a balance detector after passing through the first optical filter, forming a first branch;
the second light beam is output to an optical attenuator, the second light beam after passing through the optical attenuator is output to a second phase modulator, the second phase modulator receives a second radio frequency signal sent by the radio frequency signal and modulates the second radio frequency signal onto an optical signal in the second light beam after passing through the optical attenuator, the second phase modulator outputs the modulated second light beam to a second optical filter, the second light beam is output to the other end of a balance detector after passing through the second optical filter to form a second branch, and the balance detector demodulates the optical signals in the first branch and the second branch to obtain signals suppressed by IMD3 and IMD5 at the same time.
Further, an output end of the laser is connected to an input end of the third phase modulator, an output end of the third phase modulator is connected to an input end of the 3dB coupler, a first output end of the 3dB coupler is connected to an input end of the first phase modulator, an output end of the first phase modulator is connected to an input end of the first optical filter, and an output end of the first optical filter is connected to a first input end of the balanced detector;
a second output end of the 3dB coupler is connected to an input end of the optical attenuator, an output end of the optical attenuator is connected to an input end of the second phase modulator, an output end of the second phase modulator is connected to an input end of the second optical filter, and an output end of the second optical filter is connected to a second input end of the balanced detector.
Further, the local oscillator signal is input into the third phase modulator and used as a modulation signal of the third phase modulator to modulate an optical signal in a light beam emitted by the laser, the radio frequency signal is divided into two paths, wherein the first path forms a first radio frequency signal after passing through the electrical attenuator and is input into the first phase modulator and is used as a modulation signal of the first phase modulator to modulate the first light beam, and the second path is a second radio frequency signal and is directly input into the second phase modulator and is used as a modulation signal of the second phase modulator to modulate the second light beam.
Further, the beam optical signal S101 generated by the laser is represented as:
Figure BDA0002636054350000031
wherein E isS101For the light field emitted by the laser, TMAttenuation coefficient, P, generated for the transmission of the entire systemINIs the optical power output by the laser, j is an imaginary number, e is a natural constant, ωcIs the angular frequency of the optical carrier and t is a time variable.
Further, in the case of the two-tone test, the second rf signal S201 in the two-tone signal of the rf input is represented as:
VS201＝V1[sin(ω1t)+sin(ω2t)]
wherein, VS201For the output second radio frequency signal, ω1And ω2For the frequency of the diphone signal, t represents a time variable, V1Is the peak voltage, t is the time variable;
the attenuation power of the electric attenuator is x (dB) and leads
Figure BDA0002636054350000044
The first rf signal S202 is represented as:
VS202＝V2[sin(ω1t)+sin(ω2t)]
wherein, VS202Is the output first radio frequency signal, omega1And ω2Is the frequency of the diphone signal, t represents a time variable, t is a time variable, V2＝b·V1。
Further, the local oscillation signal S203 is represented as:
VS203＝V0sin(ωLOt)
wherein, VS203For output local oscillator signal, V0Is the peak voltage, ω, of the local oscillator signalLOIs the angular frequency of the local oscillator signal, and t is a time variable.
Further, the optical signal S102 modulated by the third phase modulator is represented as:
Figure BDA0002636054350000041
wherein E isS102For the optical signal output by the third phase modulator, TMAttenuation coefficient, P, generated for the transmission of the entire systemINIs the optical power output by the laser, j is an imaginary number, e is a natural constant, ωcIs the angular frequency of the optical carrier, t is a time variable, ωLOIs the angular frequency, m, of the local oscillator signal0Is the modulation index of the local oscillator signal,
Figure BDA0002636054350000042
V0is the peak voltage, V, of the local oscillator signalπIs a half-wave voltage, and m is a modulation index.
Further, the optical signal S103 modulated by the first phase modulator is represented as:
Figure BDA0002636054350000043
the optical signal S104 modulated by the second phase modulator is represented as:
Figure BDA0002636054350000051
wherein E isS103Representing the optical signal modulated by the first phase modulator, ES104Representing the optical signal, T, modulated by a second phase modulatorMAttenuation coefficient generated for whole system transmission，PINIs the optical power output by the laser, j is an imaginary number, e is a natural constant, ωcIs the angular frequency of the optical carrier, t is a time variable, ωLOIs the angular frequency, m, of the local oscillator signal0Is the modulation index of the local oscillator signal,
Figure BDA0002636054350000052
ω1and ω2For the angular frequency of a diphone signal, the modulation index of the diphone signal is
Figure BDA0002636054350000053
V0Is the peak voltage of the local oscillator signal,
Figure BDA0002636054350000054
m2＝b·m1，Jn(m) n-th order Bessel coefficient class 1 of parameter m, n0、n1、n2Are all integers, VπIs a half-wave voltage, and m is a modulation index.
Further, the optical signal S105 selected by the first optical filter is represented as:
Figure BDA0002636054350000055
the optical signal S106 selected by the second optical filter is represented as:
Figure BDA0002636054350000056
wherein E isS105Optical signal representing selection of the first optical filter, ES106Optical signal, T, representing selection of a first optical filterMAttenuation coefficient, P, generated for the transmission of the entire systemINIs the optical power output by the laser, j is an imaginary number, e is a natural constant, ωcIs the angular frequency of the optical carrier, t is a time variable, ωLOIs the angular frequency, m, of the local oscillator signal0Is the modulation index of the local oscillator signal,
Figure BDA0002636054350000057
ω1and ω2For the angular frequency of a diphone signal, the modulation index of the diphone signal is
Figure BDA0002636054350000058
V0Is the peak voltage of the local oscillator signal,
Figure BDA0002636054350000059
m2＝b·m1，Jn(m) n-th order Bessel coefficient class 1 of parameter m, n0、n1、n2Are all integers, VπIs a half-wave voltage, and m is a modulation index.
Further, in the process of processing the optical signal S105 and the optical signal S106 by the balanced detector, firstly, the beat frequency is performed on the optical signal S105 and the optical signal S106, and then the difference value is output, after the beat frequency of the optical signal S105, the IMD3 component expression of the down-conversion signal is as follows:
Figure BDA0002636054350000061
wherein, I1-IMD3Representing IMD3, TMAttenuation coefficient, P, generated for the transmission of the entire systemINOptical power, omega, output by a lasercIs the angular frequency of optical carrier, t is time variable, and the modulation index of local oscillator signal is
Figure BDA0002636054350000062
The two-tone signal has a modulation index of
Figure BDA0002636054350000063
ωLOIs the angular frequency, omega, of the local oscillator signal1And ω2Is the angular frequency, J, of the diphone signaln(m) n-th order Bessel coefficient class 1 of parameter m, n0、n1、n2Are all integers, ω10＝ω1-ωLO，ω20＝ω2-ωLOIs a down-converted signal that is,
Figure BDA0002636054350000064
is to balance the responsivity, V, of the detectorπIs a half-wave voltage, and m is a modulation index.
Compared with the prior art, the method for suppressing the third-order and fifth-order intermodulation distortion of the microwave photon down-conversion link has the advantages that the laser emits light beams, the light beams are output after being modulated by the local oscillator signal received by the third phase modulator, the modulation of the third phase modulator is controlled by controlling the power of the local oscillator signal, the signal modulated by the third phase modulator is divided into a first light beam and a second light beam by the 3dB coupler, the first light beam is modulated by the first phase modulator, then is subjected to the first optical filter, and is output to the first input end of the balance detector after passing through the first optical filter, so that the first branch is formed. And the second light beam is output to the second phase modulator after passing through the optical attenuator, is output to the second optical filter after being modulated by the second phase modulator, and is output to the second input end of the balance detector after passing through the second optical filter to form a second branch. Through the arrangement of the first branch and the second branch, the optical power of the two branches is in a certain proportion to the power of the first radio-frequency signal and the power of the second radio-frequency signal in the process, and the first branch and the second branch are finally input into a balanced detector to demodulate to obtain signals which are simultaneously suppressed by IMD3 and IMD5, so that the spurious-free dynamic range of a down-conversion link is improved.
Furthermore, under the condition of the same radio frequency input power, the improvement effect of directly filtering out the upper sideband demodulation scheme after phase modulation is obvious, and the modulation effect of the phase modulator can be realized by controlling the power of the radio frequency signal, so that the controllability of the whole link is realized, and the spurious-free dynamic range of the down-conversion link is further improved.
Furthermore, the second branch is only added with an optical attenuator compared with the first branch in structure, so that the working states of the first branch and the second branch are consistent, the suppression of intermodulation distortion is realized by reasonably adjusting the relation ratio of the optical power ratio and the input radio frequency, and the control of the ratio of the whole link is realized by adjusting the optical attenuator and the electrical attenuator in the link. Meanwhile, the problem of bias point drift is avoided by adopting three phase modulators and adjusting modulation signals of the phase modulators.
Drawings
Fig. 1 is a schematic block diagram of a microwave photon down-conversion link based on fifth-order intermodulation distortion suppression according to an embodiment of the present invention;
FIG. 2 is a diagram illustrating the improvement of the intermodulation distortion suppression under a constant input RF power in the embodiment of the present invention;
FIG. 3 is a diagram illustrating the results of the spurious-free dynamic range of the system under the condition of varying input RF power according to the embodiment of the present invention.
Detailed Description
In order that the objects and advantages of the invention will be more clearly understood, the invention is further described below with reference to examples; it should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only for explaining the technical principle of the present invention, and do not limit the scope of the present invention.
It should be noted that in the description of the present invention, the terms of direction or positional relationship indicated by the terms "upper", "lower", "left", "right", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, which are only for convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.
Furthermore, it should be noted that, in the description of the present invention, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
First, the noun terms to which one or more embodiments of the present specification relate are explained.
SFDR: english is called as a whole: spurrious-free dynamic range, which is called as follows: the spurious-free dynamic range, which is measured only by the worst-case spectral artifact relative to the full-scale range dBFS or the input signal level dBc of the converter, is one of the main performance indicators of the converter, and improving the spurious-free dynamic range of the converter plays an important role in improving the performance of the converter.
IMD 3: english is called as a whole: third order interaction description, Chinese full name: the third-order intermodulation distortion is very close to a fundamental frequency term in a frequency domain, is difficult to be filtered by a filter directly, and is the primary factor for limiting the SFDR of a link.
IMD 5: english is called as a whole: the Fifth order interaction description, Chinese full name: the fifth-order intermodulation distortion, which is very close to the fundamental frequency term in the frequency domain, becomes a main limiting factor for further improving the link SFDR.
The spurious-free dynamic range (SFDR) is an important performance index for measuring the MPL down-conversion link.
Referring to fig. 1, the present invention provides a method for suppressing third-order and fifth-order intermodulation distortion of a microwave photon down-conversion link, including a laser, a phase modulator, a 3dB coupler, an optical filter, a balanced detector, an optical attenuator, and an electrical attenuator.
Wherein the phase modulator comprises a first phase modulator, a second phase modulator and a third phase modulator, and the optical filter comprises a first optical filter and a second optical filter.
Specifically, in the embodiment of the present invention, the laser generates a light beam, the light beam passes through the third phase modulator, the third phase modulator receives a local oscillator signal and modulates the local oscillator signal onto an optical signal in the light beam, the third phase modulator outputs the modulated light beam, the 3dB coupler divides the light beam modulated by the third phase modulator into a first light beam and a second light beam, the first light beam is output to the first phase modulator, the first phase modulator receives a first radio frequency signal, which is sent by a radio frequency signal and passes through an electrical attenuator, and modulates the first radio frequency signal onto an optical signal in the first light beam, the first phase modulator outputs the modulated first light beam to a first optical filter, and the first light beam is output to one end of a balance detector after passing through the first optical filter, so as to form a first branch.
Specifically, in the embodiment of the present invention, the second light beam is output to an optical attenuator, the second light beam after passing through the optical attenuator is output to a second phase modulator, the second phase modulator receives a second radio frequency signal emitted by the radio frequency signal and modulates the second radio frequency signal onto an optical signal in the second light beam after passing through the optical attenuator, the second phase modulator outputs the modulated second light beam to a second optical filter, and the second light beam after passing through the second optical filter is output to the other end of the balanced detector, so as to form a second branch.
Specifically, in the embodiment of the present invention, an output end of the laser is connected to an input end of the third phase modulator, an output end of the third phase modulator is connected to an input end of the 3dB coupler, a first output end of the 3dB coupler is connected to an input end of the first phase modulator, an output end of the first phase modulator is connected to an input end of the first optical filter, and an output end of the first optical filter is connected to a first input end of the balanced detector.
Specifically, in this embodiment of the present invention, the second output terminal of the 3dB coupler is connected to the input terminal of the optical attenuator, the output terminal of the optical attenuator is connected to the input terminal of the second phase modulator, the output terminal of the second phase modulator is connected to the input terminal of the second optical filter, and the output terminal of the second optical filter is connected to the second input terminal of the balanced detector.
Specifically, in the embodiment of the present invention, the local oscillator signal is input to the third phase modulator and is used as a modulation signal of the third phase modulator to modulate an optical signal in an optical beam emitted by a laser, the radio frequency signal is divided into two paths, where the first path passes through an electrical attenuator to form a first radio frequency signal, the first radio frequency signal is input to the first phase modulator and is used as a modulation signal of the first phase modulator to modulate the first optical beam, and the second path is used as a second radio frequency signal, the second radio frequency signal is directly input to the second phase modulator and is used as a modulation signal of the second phase modulator to modulate the second optical beam.
Specifically, in the embodiment of the present invention, the laser emits a light beam, and the light beam is modulated by a local oscillator signal received by a third phase modulator and then output, where the modulation of the third phase modulator is controlled by controlling the power of the local oscillator signal, the signal modulated by the third phase modulator divides an optical signal into a first light beam and a second light beam by a 3dB coupler, the first light beam is modulated by a first phase modulator, then is subjected to a first optical filter, and is output to a first input end of the balanced detector after passing through the first optical filter, so as to form a first branch.
Specifically, in the embodiment of the present invention, the second light beam passes through the optical attenuator and is output to the second phase modulator, is modulated by the second phase modulator and is output to the second optical filter, and is output to the second input end of the balanced detector after passing through the second optical filter, so as to form the second branch.
The modulation signal of the first phase modulator in the first branch is a first radio frequency signal, the modulation signal of the second phase modulator in the second branch is a second radio frequency signal, the first radio frequency signal forms a first radio frequency signal after passing through the electric attenuator and is input into the first phase modulator, and the second radio frequency signal is directly input into the second phase modulator. The optical power of the first branch and the second branch has a certain proportional relationship with the power of the first radio frequency signal and the power of the second radio frequency signal, the optical signals input into the balanced detector by the first branch and the second branch are demodulated in the balanced detector to obtain signals which are simultaneously suppressed by the IMD3 and the IMD5, and therefore the spurious-free dynamic range of the down-conversion link is improved.
Specifically, in this embodiment of the present invention, an optical signal of a light beam generated by the laser is S101, the local oscillator signal is S203, and the local oscillator signal S203 is input to the third phase modulator and modulated onto the optical signal S101 received by the third phase modulator and emitted by the laser, so as to form an optical signal S102. The optical signal S102 is split into a first beam and a second beam after passing through the 3dB coupler,
specifically, in the embodiment of the present invention, the first light beam is output to the first phase modulator, wherein the first path of radio frequency signal is connected in series with an electrical attenuator, and is attenuated by the electrical attenuator to form a first radio frequency signal S202 and is input to the first phase modulator, the first phase modulator modulates the first light beam by using the first radio frequency signal S202, the first phase modulator outputs a modulated optical signal S103, the first optical filter receives the optical signal S103 modulated by the first phase modulator and selects the optical signal S103 to form an optical signal S105, and the first optical filter outputs the selected optical signal S105 to the first input end of the balanced detector.
Specifically, in this embodiment of the present invention, the optical power of the optical signal in the second optical beam is attenuated by an optical attenuator and then output to the second phase modulator, the second phase modulator receives the second radio frequency signal S201 output by the radio frequency, the second phase modulation signal modulates the second radio frequency signal S201 onto the second optical beam attenuated by the optical attenuator, the second phase modulator outputs the modulated optical signal S104, the second optical filter receives the optical signal S104 modulated by the second phase modulator and selects the optical signal S104 to form the optical signal S106, and the second optical filter outputs the selected optical signal S106 to the second input end of the balanced detector.
Specifically, in the embodiment of the present invention, the balanced detector performs photoelectric conversion on the received optical signal S105 of the first branch and the received optical signal S106 of the second branch, and outputs an electrical signal to the spectrometer for analysis.
The optical signal of the beam generated by the laser is S101, which is expressed as:
Figure BDA0002636054350000101
wherein E isS101For the light field emitted by the laser, TMAttenuation coefficient, P, generated for the transmission of the entire systemINIs the optical power output by the laser, j is an imaginary number, e is a natural constant, ωcIs the angular frequency of the optical carrier and t is a time variable.
In the case of the two-tone test, the second rf signal S201 of the input two-tone signal can be represented as:
VS201＝V1[sin(ω1t)+sin(ω2t)]
wherein, VS201For the output second radio frequency signal, ω1And ω2For the frequency of the diphone signal, t represents a time variable, V1Is the peak voltage and t is the time variable.
The attenuation power of the electric attenuator is x (dB) and leads
Figure BDA0002636054350000114
The first rf signal S202 may be represented as:
VS202＝V2[sin(ω1t)+sin(ω2t)]
wherein, VS202Is the output first radio frequency signal, omega1And ω2Is the frequency of the diphone signal, t represents a time variable, t is a time variable, V2＝b·V1。
The local oscillation signal S203 is represented as:
VS203＝V0sin(ωLOt)
wherein, VS203To be transportedOutput local oscillator signal, V0Is the peak voltage, ω, of the local oscillator signalLOIs the angular frequency of the local oscillator signal, and t is a time variable.
The optical signal S102 modulated by the third phase modulator is represented as:
Figure BDA0002636054350000111
wherein E isS102For the optical signal output by the third phase modulator, TMAttenuation coefficient, P, generated for the transmission of the entire systemINIs the optical power output by the laser, j is an imaginary number, e is a natural constant, ωcIs the angular frequency of the optical carrier, t is a time variable, ωLOIs the angular frequency, m, of the local oscillator signal0Is the modulation index of the local oscillator signal,
Figure BDA0002636054350000112
V0is the peak voltage, V, of the local oscillator signalπIs a half-wave voltage.
The optical signal S103 modulated by the first phase modulator can be represented as:
Figure BDA0002636054350000113
wherein E isS103Representing the optical signal, T, modulated by the first phase modulatorMAttenuation coefficient, P, generated for the transmission of the entire systemINIs the optical power output by the laser, j is an imaginary number, e is a natural constant, ωcIs the angular frequency of the optical carrier, t is a time variable, ωLOIs the angular frequency, m, of the local oscillator signal0Is the modulation index of the local oscillator signal,
Figure BDA0002636054350000121
ω1and ω2For the angular frequency of a diphone signal, the modulation index of the diphone signal is
Figure BDA0002636054350000122
V0Is the peak voltage of the local oscillator signal,
Figure BDA0002636054350000123
m2＝b·m1，Jn(m) n-th order Bessel coefficient class 1 of parameter m, n0、n1、n2Are all integers. VπIs a half-wave voltage.
The attenuation power of the optical attenuator is
Figure BDA0002636054350000124
The optical signal S104 modulated by the second phase modulator can be represented as:
Figure BDA0002636054350000125
wherein E isS104Representing the optical signal, T, modulated by a second phase modulatorMAttenuation coefficient, P, generated for the transmission of the entire systemINIs the optical power output by the laser, j is an imaginary number, e is a natural constant, ωcIs the angular frequency of the optical carrier, t is a time variable, ωLOIs the angular frequency, m, of the local oscillator signal0Is the modulation index of the local oscillator signal,
Figure BDA0002636054350000126
ω1and ω2For the angular frequency of a diphone signal, the modulation index of the diphone signal is
Figure BDA0002636054350000127
V0Is the peak voltage of the local oscillator signal,
Figure BDA0002636054350000128
m2＝b·m1，Jn(m) n-th order Bessel coefficient class 1 of parameter m, n0、n1、n2Are all integers. VπIs a half-wave voltage, and m is a modulation index.
The optical signal S105 selected by the first optical filter can be expressed as:
Figure BDA0002636054350000129
wherein E isS105Optical signal, T, representing selection of a first optical filterMAttenuation coefficient, P, generated for the transmission of the entire systemINIs the optical power output by the laser, j is an imaginary number, e is a natural constant, ωcIs the angular frequency of the optical carrier, t is a time variable, ωLOIs the angular frequency, m, of the local oscillator signal0Is the modulation index of the local oscillator signal,
Figure BDA0002636054350000131
ω1and ω2For the angular frequency of a diphone signal, the modulation index of the diphone signal is
Figure BDA0002636054350000132
V0Is the peak voltage of the local oscillator signal,
Figure BDA0002636054350000133
m2＝b·m1，Jn(m) n-th order Bessel coefficient class 1 of parameter m, n0、n1、n2Are all integers. VπIs a half-wave voltage, and m is a modulation index.
The optical signal S106 selected by the second optical filter can be represented as:
Figure BDA0002636054350000134
wherein E isS106Optical signal, T, representing selection of a first optical filterMAttenuation coefficient, P, generated for the transmission of the entire systemINIs the optical power output by the laser, j is an imaginary number, e is a natural constant, ωcIs the angular frequency of the optical carrier, t is a time variable, ωLOIs the angular frequency, m, of the local oscillator signal0Is the modulation index of the local oscillator signal,
Figure BDA0002636054350000135
ω1and ω2For the angular frequency of a diphone signal, the modulation index of the diphone signal is
Figure BDA0002636054350000136
V0Is the peak voltage of the local oscillator signal,
Figure BDA0002636054350000137
m2＝b·m1，Jn(m) n-th order Bessel coefficient class 1 of parameter m, n0、n1、n2Are all integers. VπIs a half-wave voltage, and m is a modulation index.
In the process of processing the optical signals S105 and S106 by the balanced detector, firstly, the beat frequency is performed on the optical signals S105 and S106, and then the difference is output. After the optical signal S105 is beat-frequency, the IMD3 component of the down-converted signal is expressed as follows:
Figure BDA0002636054350000138
wherein, I1-IMD3Representing IMD3, TMAttenuation coefficient, P, generated for the transmission of the entire systemINOptical power, omega, output by a lasercIs the angular frequency of optical carrier, t is time variable, and the modulation index of local oscillator signal is
Figure BDA0002636054350000139
The two-tone signal has a modulation index of
Figure BDA00026360543500001310
ωLOIs the angular frequency, omega, of the local oscillator signal1And ω2The angular frequency of the diphone signal. J. the design is a squaren(m) n-th order Bessel coefficient class 1 of parameter m, n0、n1、n2Are all integers. VπIs half-wave voltage, m is modulation index, omega10＝ω1-ωLO，ω20＝ω2-ωLOIs a down-converted signal that is,
Figure BDA0002636054350000143
is to balance the detector responsivity.
When the equation satisfies m02.166, IMD3 in the first branch is suppressed. IMD3 in S106 is also suppressed similarly.
The general expression of the electric signal output by the balance detector after being expanded by the Taylor expansion is as follows:
Figure BDA0002636054350000141
wherein the content of the first and second substances,
Figure BDA0002636054350000142
is the coefficient resulting from the taylor expansion of the system at a certain point a.
The input x to the SFDR is the two-tone signal S201 or S202. The component corresponding to IMD5 term is x5Thus, the output expression of IMD5, which may be expressed as optical signal S105, is:
I1-IMD5＝h5·{V2[sin(ω1t)+sin(ω2t)]}5＝h5(bV1)5{[sin(ω1t)+sin(ω2t)]}5
h5is the constant obtained by taylor series expansion of the transfer function of the first branch, and is important to be a definite and unique constant for any system. Omega1And ω2Is the angular frequency, V, of the diphone signal1Is the peak voltage, where V2＝b·V1And t is a time variable.
The IMD5 in the optical signal S106 is derived from the 5 th power of the two-tone signal, and can be represented as:
I2-IMD5＝a·h5·(V1)5{[sin(ω1t)+sin(ω2t]}5
h5is a constant term obtained by taylor series expansion of the transfer function of the first branch. Omega1And ω2Is the angular frequency, V, of the diphone signal1Is the peak voltage. Since the first branch and the second branch are operated in the same state, only one optical attenuator is structurally different, and therefore the factor alpha is added.
Finally, the output of the balanced probe with respect to IMD5 at this time may be expressed as:
BPD-IMD 5∝a·h5·(V1)5{[sin(ω1t)+sin(ω2t)]}5-h5·(bV1)5{[sin(ω1t)+sin(ω2t)]}5
h5is a constant term, omega, obtained by Taylor series expansion of the transfer function of the first branch1And ω2Is the angular frequency, V, of the diphone signal1Is the peak voltage, where V2＝b·V1. A and b are constant factors introduced by the attenuator. The link satisfies the relationship a- (b)5IMD5 was also inhibited at 0. Wherein a set of typical values is
Figure BDA0002636054350000151
b0.644. In the embodiment of the invention, the suppression of intermodulation distortion is realized by reasonably adjusting the relation ratio of the optical power ratio and the input radio frequency, and it is obvious that the patent includes but is not limited to realizing the control of the ratio by an attenuator.
Referring to fig. 2, a comparison graph of Optisystem simulation of the demodulation scheme and the proposed scheme with phase modulation and direct filtering of the upper sideband under the same rf input power is shown. When the input power of the local oscillator signal is 29.8dBm and the input power of the double tone signal is 28.9dBm, the CIR of the IMD3 at 450MHz is about 59.5dB, and is improved by 30.6 dB.
Please refer to fig. 3, which shows a fitting result chart of spurious-free dynamic range obtained by performing Optisystem simulation analysis under different rf input powers. Under the condition that the noise floor is-166 dBm, the spurious-free dynamic range of the proposed scheme can reach 127.4 dB-Hz6/7。
So far, the technical solutions of the present invention have been described in connection with the preferred embodiments shown in the drawings, but it is easily understood by those skilled in the art that the scope of the present invention is obviously not limited to these specific embodiments. Equivalent changes or substitutions of related technical features can be made by those skilled in the art without departing from the principle of the invention, and the technical scheme after the changes or substitutions can fall into the protection scope of the invention.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention; various modifications and alterations to this invention will become apparent to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (4)

1. A method for suppressing the third-order and fifth-order intermodulation distortion of microwave photon down-conversion link is characterized by that the laser generates light beam, the light beam passes through the third phase modulator, the third phase modulator receives the local oscillator signal and modulates the local oscillator signal onto the optical signal in the optical beam, the third phase modulator outputs the modulated light beam, the 3dB coupler divides the light beam modulated by the third phase modulator into a first light beam and a second light beam, the first light beam is output to the first phase modulator, the first phase modulator receives a first radio frequency signal from the radio frequency signal via the electrical attenuator and modulates the first radio frequency signal onto the optical signal in the first optical beam, the first phase modulator outputs the modulated first light beam to a first optical filter, and the first light beam is output to one end of a balance detector after passing through the first optical filter to form a first branch;
the second light beam is output to an optical attenuator, the second light beam after passing through the optical attenuator is output to a second phase modulator, the second phase modulator receives a second radio-frequency signal sent by the radio-frequency signal and modulates the second radio-frequency signal onto an optical signal in the second light beam after passing through the optical attenuator, the second phase modulator outputs the modulated second light beam to a second optical filter, the second light beam is output to the other end of a balance detector after passing through the second optical filter to form a second branch, and the balance detector demodulates the optical signals in the first branch and the second branch to obtain signals suppressed by IMD3 and IMD 5;
the beam optical signal S101 generated by the laser is represented as:
Figure FDA0003375584560000011
wherein E isS101For the light field emitted by the laser, TMAttenuation coefficient, P, generated for the transmission of the entire systemINIs the optical power output by the laser, j is an imaginary number, e is a natural constant, ωcIs the angular frequency of the optical carrier, t is the time variable;
in the case of the two-tone test, the second rf signal S201 of the two-tone signals of the rf input is represented as:
VS201＝V1[sin(ω1t)+sin(ω2t)]
wherein, VS201For the output second radio frequency signal, ω1And ω2For the frequency of the diphone signal, t represents a time variable, V1Is the peak voltage, t is the time variable;
the attenuation power of the electric attenuator is x (dB) and leads
Figure FDA0003375584560000012
The first rf signal S202 is represented as:
VS202＝V2[sin(ω1t)+sin(ω2t)]
wherein, VS202Is the output first radio frequency signal, omega1And ω2Is the frequency of the diphone signal, t represents a time variable, t is a time variable, V2＝b·V1；
The local oscillation signal S203 is represented as:
VS203＝V0sin(ωLOt)
wherein, VS203For output local oscillator signal, V0Is the peak voltage, ω, of the local oscillator signalLOIs the angular frequency of the local oscillator signal, t is the time variable;
the optical signal S102 modulated by the third phase modulator is represented as:
Figure FDA0003375584560000021
wherein E isS102For the optical signal output by the third phase modulator, TMAttenuation coefficient, P, generated for the transmission of the entire systemINIs the optical power output by the laser, j is an imaginary number, e is a natural constant, ωcIs the angular frequency of the optical carrier, t is a time variable, ωLOIs the angular frequency, m, of the local oscillator signal0Is the modulation index of the local oscillator signal,
Figure FDA0003375584560000022
V0is the peak voltage, V, of the local oscillator signalπIs half-wave voltage, and m is modulation index;
the optical signal S103 modulated by the first phase modulator is represented as:
Figure FDA0003375584560000023
the optical signal S104 modulated by the second phase modulator is represented as:
Figure FDA0003375584560000024
wherein E isS103Representing the optical signal modulated by the first phase modulator, ES104Representing the optical signal, T, modulated by a second phase modulatorMAttenuation coefficient, P, generated for the transmission of the entire systemINIs the optical power output by the laser, j is an imaginary number, e is a natural constant, ωcBeing light carriersAngular frequency of the wave, t being a time variable, ωLOIs the angular frequency, m, of the local oscillator signal0Is the modulation index of the local oscillator signal,
Figure FDA0003375584560000025
ω1and ω2For the angular frequency of a diphone signal, the modulation index of the diphone signal is
Figure FDA0003375584560000026
V0Is the peak voltage of the local oscillator signal,
Figure FDA0003375584560000027
m2＝b·m1，Jn(m) n-th order Bessel coefficient class 1 of parameter m, n0、n1、n2Are all integers, VπIs half-wave voltage, and m is modulation index;
the optical signal S105 selected by the first optical filter is represented as:
Figure FDA0003375584560000031
the optical signal S106 selected by the second optical filter is represented as:
Figure FDA0003375584560000032
wherein E isS105Optical signal representing selection of the first optical filter, ES106Optical signal, T, representing selection of a first optical filterMAttenuation coefficient, P, generated for the transmission of the entire systemINIs the optical power output by the laser, j is an imaginary number, e is a natural constant, ωcIs the angular frequency of the optical carrier, t is a time variable, ωLOIs the angular frequency, m, of the local oscillator signal0Is the modulation index of the local oscillator signal,
Figure FDA0003375584560000033
ω1and ω2For the angular frequency of a diphone signal, the modulation index of the diphone signal is
Figure FDA0003375584560000034
V0Is the peak voltage of the local oscillator signal,
Figure FDA0003375584560000035
m2＝b·m1，Jn(m) n-th order Bessel coefficient class 1 of parameter m, n0、n1、n2Are all integers, VπIs a half-wave voltage, and m is a modulation index.
2. The method of claim 1, wherein an output of the laser is connected to an input of the third phase modulator, an output of the third phase modulator is connected to an input of the 3dB coupler, a first output of the 3dB coupler is connected to an input of the first phase modulator, an output of the first phase modulator is connected to an input of the first optical filter, and an output of the first optical filter is connected to a first input of the balanced detector;
a second output end of the 3dB coupler is connected to an input end of the optical attenuator, an output end of the optical attenuator is connected to an input end of the second phase modulator, an output end of the second phase modulator is connected to an input end of the second optical filter, and an output end of the second optical filter is connected to a second input end of the balanced detector.
3. The method according to claim 2, wherein the local oscillator signal is input to the third phase modulator and used as a modulation signal of the third phase modulator to modulate an optical signal in a light beam emitted by a laser, the radio frequency signal is divided into two paths, the first path passes through an electrical attenuator to form a first radio frequency signal, the first radio frequency signal is input to the first phase modulator and used as a modulation signal of the first phase modulator to modulate the first light beam, and the second path is used as a second radio frequency signal, the second radio frequency signal is directly input to the second phase modulator and used as a modulation signal of the second phase modulator to modulate the second light beam.
4. The method according to claim 3, wherein during the processing of the optical signals S105 and S106 by the balanced detector, the optical signals S105 and S106 are first beaten, and then the difference is output, and after the beating of the optical signals S105, the IMD3 component of the down-converted signal is expressed as follows:
Figure FDA0003375584560000041
wherein, I1-IMD3Representing IMD3, TMAttenuation coefficient, P, generated for the transmission of the entire systemINOptical power, omega, output by a lasercIs the angular frequency of optical carrier, t is time variable, and the modulation index of local oscillator signal is
Figure FDA0003375584560000042
The two-tone signal has a modulation index of
Figure FDA0003375584560000043
ωLOIs the angular frequency of the local oscillator signal omega1And ω2Is the angular frequency, J, of the diphone signaln(m) n-th order Bessel coefficient class 1 of parameter m, n0、n1、n2Are all integers, ω10＝ω1-ωLO，ω20＝ω2-ωLOIs a down-converted signal that is,
Figure FDA0003375584560000044
is to balance the responsivity, V, of the detectorπIs a half-wave voltage, and m is a modulation index.
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"基于五阶交调抑制的大动态微波光子下变频链路";张钧凯等人;《空军预警学院学报》;20181231;第32卷(第6期);参见该论文1-4页，附图1-4 *

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