CN114389698A - Microwave signal generating device and method - Google Patents
Microwave signal generating device and method Download PDFInfo
- Publication number
- CN114389698A CN114389698A CN202111595088.2A CN202111595088A CN114389698A CN 114389698 A CN114389698 A CN 114389698A CN 202111595088 A CN202111595088 A CN 202111595088A CN 114389698 A CN114389698 A CN 114389698A
- Authority
- CN
- China
- Prior art keywords
- signal
- frequency
- circulator
- wave signal
- bragg grating
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000000034 method Methods 0.000 title claims abstract description 44
- 239000000835 fiber Substances 0.000 claims abstract description 153
- 239000013307 optical fiber Substances 0.000 claims abstract description 86
- 230000000694 effects Effects 0.000 claims abstract description 33
- 230000005540 biological transmission Effects 0.000 claims description 76
- 230000003287 optical effect Effects 0.000 claims description 39
- 238000001228 spectrum Methods 0.000 claims description 39
- 238000000411 transmission spectrum Methods 0.000 claims description 30
- 230000010287 polarization Effects 0.000 claims description 22
- 230000008878 coupling Effects 0.000 claims description 9
- 238000010168 coupling process Methods 0.000 claims description 9
- 238000005859 coupling reaction Methods 0.000 claims description 9
- 239000006185 dispersion Substances 0.000 claims description 6
- 238000005086 pumping Methods 0.000 claims description 4
- 238000010009 beating Methods 0.000 claims description 3
- 102100029469 WD repeat and HMG-box DNA-binding protein 1 Human genes 0.000 claims description 2
- 101710097421 WD repeat and HMG-box DNA-binding protein 1 Proteins 0.000 claims description 2
- 230000007274 generation of a signal involved in cell-cell signaling Effects 0.000 claims 2
- 230000010354 integration Effects 0.000 abstract description 2
- 238000010586 diagram Methods 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 238000004088 simulation Methods 0.000 description 5
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 230000035559 beat frequency Effects 0.000 description 2
- 238000005094 computer simulation Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000009022 nonlinear effect Effects 0.000 description 2
- 229910052691 Erbium Inorganic materials 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000013016 damping Methods 0.000 description 1
- UYAHIZSMUZPPFV-UHFFFAOYSA-N erbium Chemical compound [Er] UYAHIZSMUZPPFV-UHFFFAOYSA-N 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 230000009021 linear effect Effects 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 238000012163 sequencing technique Methods 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
- 230000008685 targeting Effects 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/25—Arrangements specific to fibre transmission
- H04B10/2575—Radio-over-fibre, e.g. radio frequency signal modulated onto an optical carrier
- H04B10/25752—Optical arrangements for wireless networks
- H04B10/25758—Optical arrangements for wireless networks between a central unit and a single remote unit by means of an optical fibre
- H04B10/25759—Details of the reception of RF signal or the optical conversion before the optical fibre
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/29—Repeaters
- H04B10/291—Repeaters in which processing or amplification is carried out without conversion of the main signal from optical form
- H04B10/2912—Repeaters in which processing or amplification is carried out without conversion of the main signal from optical form characterised by the medium used for amplification or processing
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/29—Repeaters
- H04B10/291—Repeaters in which processing or amplification is carried out without conversion of the main signal from optical form
- H04B10/293—Signal power control
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
- H04B10/501—Structural aspects
- H04B10/503—Laser transmitters
- H04B10/505—Laser transmitters using external modulation
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Optics & Photonics (AREA)
- Optical Communication System (AREA)
- Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)
Abstract
The invention discloses a microwave signal generating device and method, which adopts an all-optical device, utilizes the electro-optical modulation principle of a Mach-Zehnder modulator and the SBS effect in an optical fiber to generate microwave signals, has a simple system structure and few adopted devices, thereby having higher stability and being easier for photoelectric integration. In addition, the frequency of the microwave signal generated by the invention is in a multiple relation with the frequency of the radio frequency signal for driving the Mach-Zehnder modulator and the fiber Brillouin frequency shift, so that the frequency of the generated high-frequency microwave signal can be continuously tuned along with the frequency of the radio frequency signal for driving the Mach-Zehnder modulator by continuously adjusting the frequency of the radio frequency signal for driving the Mach-Zehnder modulator.
Description
Technical Field
The invention relates to the technical field of microwave photonics, in particular to a device and a method for generating a microwave signal.
Background
Microwave signals are preferred because of their high frequency, ability to resolve spectral congestion in the low frequency region, and ability to provide large transmission bandwidths. In the sub 6G frequency band of the current 5G base station, microwave signals are used as radio frequency carrier transmission signals. The quality of the radio frequency carrier transmission signal determines the data transmission rate in the wireless communication system, so how to generate the microwave signal with narrow line width, low phase noise and high stability is a hot spot of research of people at present.
Disclosure of Invention
The embodiment of the invention provides a device and a method for generating microwave signals, which are used for generating microwave signals with tunable frequency and low phase noise.
The embodiment of the invention provides a microwave signal generating device, which comprises: the device comprises a laser, a polarization controller, a Mach-Zehnder modulator, a first circulator, a fiber Bragg grating, an erbium-doped fiber amplifier, a second circulator, an optical fiber, a coupler and a photoelectric detector; wherein,
the laser is used for generating an optical signal and transmitting the optical signal to the polarization controller as a carrier signal;
the polarization controller is used for adjusting the polarization state of the optical signal and transmitting the optical signal to the Mach-Zehnder modulator;
the Mach-Zehnder modulator is used for being driven by a tunable radio-frequency signal and a direct-current signal, modulating the carrier signal, generating a modulation signal and outputting the modulation signal to the first circulator;
the first circulator is used for transmitting the modulation signal to the fiber Bragg grating and transmitting a reflection modulation signal reflected by the fiber Bragg grating to the erbium-doped fiber amplifier, and the reflection modulation signal is a part of the modulation signal frequency in the reflection spectrum of the fiber Bragg grating;
the fiber Bragg grating is used for transmitting a transmission modulation signal to the coupler, wherein the transmission modulation signal is the part of the modulation signal frequency in the transmission spectrum of the fiber Bragg grating;
the erbium-doped fiber amplifier is used for amplifying the power of the reflection modulation signal and transmitting the power of the reflection modulation signal to the second circulator as a pump wave signal, and the power of the pump wave signal is greater than the threshold value of the SBS effect generated by the fiber;
the second circulator is used for transmitting the pump wave signal to the optical fiber and transmitting a Stokes wave signal generated by the optical fiber to the coupler;
the optical fiber is used for being excited by the pump wave signal to generate the Stokes wave signal which is opposite to the transmission direction of the pump wave signal and is shifted in frequency by at least one Brillouin frequency shift;
the coupler is used for coupling the Stokes wave signal and the transmission modulation signal and then transmitting the coupling to the photoelectric detector;
and the photoelectric detector is used for beating the Stokes wave signal and the transmission modulation signal and generating a microwave signal with the frequency of the difference between the two frequencies.
In a possible implementation manner, in the microwave signal generating apparatus provided in the embodiment of the present invention, the modulation signal generated by the mach-zehnder modulator includes a +1 order sideband signal and a-1 order sideband signal of the modulation signal.
In a possible implementation manner, in the apparatus for generating a microwave signal provided in the embodiment of the present invention, the frequency of the +1 order sideband signal is within a transmission spectrum of the fiber bragg grating, and the transmission modulation signal is the +1 order sideband signal;
the frequency of the-1 order sideband signal is in the fiber Bragg grating reflection spectrum, and the reflection modulation signal is the-1 order sideband signal.
In a possible implementation manner, in the apparatus for generating a microwave signal provided in the embodiment of the present invention, a frequency of the +1 order sideband signal is within a reflection spectrum of the fiber bragg grating, and the reflection modulation signal is the +1 order sideband signal;
the frequency of the-1 order sideband signal is in the transmission spectrum of the fiber Bragg grating, and the transmission modulation signal is the-1 order sideband signal.
In a possible implementation manner, in the microwave signal generating apparatus provided in the embodiment of the present invention, the second circulator includes 1 port, 2 ports, 3 ports, and 4 ports, and the optical fiber is connected between the 2 ports and the 3 ports of the second circulator;
the port 1 of the second circulator is used for receiving the pump wave signal and transmitting the pump wave signal to the port 2;
the port 2 of the second circulator is used for transmitting the pump wave signal into the optical fiber and transmitting a first-order Stokes wave signal generated by the optical fiber to the port 3; the transmission directions of the first-order Stokes wave signal and the pumping wave signal are opposite, and the frequency is shifted down by one Brillouin frequency shift;
the 3 ports of the second circulator are used for transmitting the primary Stokes wave signals into the optical fiber and transmitting the secondary Stokes wave signals generated by the optical fiber to the 4 ports; the transmission directions of the secondary Stokes wave signals and the primary Stokes wave signals are opposite, and the frequency is shifted down by one Brillouin frequency shift;
the 4 ports of the second circulator are used for transmitting the second-order Stokes wave signal to the coupler.
In a possible implementation manner, in the microwave signal generating apparatus provided in the embodiment of the present invention, the second circulator includes 1 port, 2 ports, and 3 ports, and the optical fiber is connected to the 2 ports of the second circulator;
the port 1 of the second circulator is used for receiving the pump wave signal and transmitting the pump wave signal to the port 2;
the port 2 of the second circulator is used for transmitting the pump wave signal into the optical fiber and transmitting a first-order Stokes wave signal generated by the optical fiber to the port 3; the transmission directions of the first-order Stokes wave signal and the pumping wave signal are opposite, and the frequency is shifted down by one Brillouin frequency shift;
the 3 ports of the second circulator are used for transmitting the first-order Stokes wave signal to the coupler.
In a possible implementation manner, in the apparatus for generating a microwave signal provided in the embodiment of the present invention, the first circulator includes 1 port, 2 ports, and 3 ports, and the fiber bragg grating is connected to the 2 ports of the first circulator;
the port 1 of the first circulator is used for receiving the modulation signal and transmitting the modulation signal to the port 2;
the 2 ports of the first circulator are used for transmitting the modulation signal to the fiber Bragg grating and transmitting a reflection modulation signal reflected by the fiber Bragg grating to the 3 ports;
and 3 ports of the first circulator are used for transmitting the reflection modulation signals to the erbium-doped fiber amplifier.
In a possible implementation manner, in the microwave signal generating apparatus provided in the embodiment of the present invention, the erbium-doped fiber amplifier is one, or the erbium-doped fiber amplifier is a plurality of erbium-doped fiber amplifiers connected in cascade.
In a possible implementation manner, in the apparatus for generating a microwave signal provided in an embodiment of the present invention, the optical fiber includes: single mode fibers or non-zero dispersion shifted fibers or dispersion shifted fibers.
On the other hand, the embodiment of the invention also provides a method for generating a microwave signal, which comprises the following steps:
the laser generates an optical signal and transmits the optical signal to the polarization controller as a carrier signal;
the polarization controller is used for adjusting the polarization state of the optical signal and transmitting the optical signal to the Mach-Zehnder modulator;
the Mach-Zehnder modulator is driven by a tunable radio-frequency signal and a direct-current signal, modulates the carrier signal, generates a modulation signal and outputs the modulation signal to the first circulator;
the first circulator transmits the modulation signal to a fiber Bragg grating;
the fiber Bragg grating transmits the transmission modulation signal with the modulation signal frequency within the fiber Bragg grating transmission spectrum to the coupler and reflects the reflection modulation signal with the modulation signal frequency within the fiber Bragg grating reflection spectrum back to the first circulator;
the first circulator transmits the reflection modulation signal to an erbium-doped fiber amplifier;
the erbium-doped fiber amplifier amplifies the power of the reflection modulation signal and transmits the power to the second circulator as a pump wave signal, and the power of the pump wave signal is greater than the threshold of the SBS effect generated by the fiber;
the second circulator transmits the pump wave signal to the optical fiber;
the optical fiber is excited by the pump wave signal to generate a SBS effect, generates a Stokes wave signal which is opposite to the transmission direction of the pump wave signal and is shifted in frequency by at least one Brillouin frequency shift, and transmits the Stokes wave signal to the second circulator;
the second circulator transmits a Stokes wave signal generated by the optical fiber to a coupler;
the coupler couples the Stokes wave signal and the transmission modulation signal and then transmits the coupling Stokes wave signal and the transmission modulation signal to the photoelectric detector;
and the photoelectric detector beats the Stokes wave signal and the transmission modulation signal to generate a microwave signal with the frequency of the difference between the two frequencies.
In a possible implementation manner, in the method for generating a microwave signal provided in an embodiment of the present invention, the mach-zehnder modulator is driven by a tunable radio frequency signal and a direct current signal, modulates the carrier signal, generates a modulation signal, and outputs the modulation signal to the first circulator, and specifically includes:
and adjusting a direct current signal for driving the Mach-Zehnder modulator to enable a bias point of the Mach-Zehnder modulator to be positioned at a minimum transmission point, and suppressing a carrier of the modulation signal, wherein the obtained modulation signal comprises a +1 order sideband signal and a-1 order sideband signal of the modulation signal.
In a possible implementation manner, in the method for generating a microwave signal provided in the embodiment of the present invention, the transmitting modulation signal with the modulation signal frequency within the fiber bragg grating transmission spectrum is transmitted to the coupler by the fiber bragg grating, and the reflecting modulation signal with the modulation signal frequency within the fiber bragg grating reflection spectrum is reflected back to the first circulator, which specifically includes:
controlling the transmission spectrum and the reflection spectrum of the fiber Bragg grating to enable the frequency of the +1 order sideband signal to be within the transmission spectrum of the fiber Bragg grating and the frequency of the-1 order sideband signal to be within the reflection spectrum of the fiber Bragg grating;
the grating fiber Bragg grating transmits the +1 order sideband signal to the coupler and reflects the-1 order sideband signal back to the first circulator.
In a possible implementation manner, in the method for generating a microwave signal provided in the embodiment of the present invention, the transmitting modulation signal with the modulation signal frequency within the fiber bragg grating transmission spectrum is transmitted to the coupler by the fiber bragg grating, and the reflecting modulation signal with the modulation signal frequency within the fiber bragg grating reflection spectrum is reflected back to the first circulator, which specifically includes:
controlling the transmission spectrum and the reflection spectrum of the fiber Bragg grating to enable the frequency of the +1 order sideband signal to be within the fiber Bragg grating reflection spectrum and the frequency of the-1 order sideband signal to be within the fiber Bragg grating transmission spectrum;
the fiber Bragg grating transmits the-1 order sideband signal to the coupler and reflects the +1 order sideband signal back to the first circulator.
In a possible implementation manner, in the method for generating a microwave signal provided in an embodiment of the present invention, the exciting, by the pump wave signal, an SBS effect of the optical fiber is generated, a stokes wave signal with a frequency shifted down by at least one brillouin frequency in a direction opposite to a transmission direction of the pump wave signal is generated, and the stokes wave signal is transmitted to the second circulator, which specifically includes:
the optical fiber is excited by the pump wave signal to generate a SBS effect, generates a first-order Stokes wave signal which is opposite to the transmission direction of the pump wave signal and is shifted down by one Brillouin frequency shift in frequency, and transmits the first-order Stokes wave signal back to the second circulator;
the second circulator transmits the first-order stokes wave signal to the optical fiber;
the optical fiber is excited again by the SBS effect by the primary Stokes wave signal, generates a secondary Stokes wave signal which is opposite to the transmission direction of the primary Stokes wave signal and is shifted down in frequency by one Brillouin frequency shift, and transmits the secondary Stokes wave signal to the second circulator so that the second circulator transmits the secondary Stokes wave signal to the coupler.
In a possible implementation manner, in the method for generating a microwave signal provided in an embodiment of the present invention, the exciting, by the pump wave signal, an SBS effect of the optical fiber is generated, a stokes wave signal with a frequency shifted down by at least one brillouin frequency in a direction opposite to a transmission direction of the pump wave signal is generated, and the stokes wave signal is transmitted to the second circulator, which specifically includes:
the optical fiber is excited by the pump wave signal to generate a SBS effect, generates a first-order Stokes wave signal which is opposite to the transmission direction of the pump wave signal and is shifted down in frequency by one Brillouin frequency shift, and transmits the first-order Stokes wave signal back to the second circulator, so that the second circulator transmits the first-order Stokes wave signal to the coupler.
In a possible implementation manner, in the method for generating a microwave signal provided in an embodiment of the present invention, the method further includes:
adjusting the frequency of the radio frequency signal driving the mach-zehnder modulator so as to obtain a tunable microwave signal.
The invention has the following beneficial effects:
the microwave signal generating device and method provided by the embodiment of the invention adopt all-optical devices, generate microwave signals by using the electro-optic modulation principle of the Mach-Zehnder modulator and the SBS effect in the optical fiber, have simple system structure and few adopted devices, and have higher stability and are easier for photoelectric integration. In addition, the frequency of the microwave signal generated by the invention is in a multiple relation with the frequency of the radio frequency signal for driving the Mach-Zehnder modulator and the fiber Brillouin frequency shift, so that the frequency of the generated high-frequency microwave signal can be continuously tuned along with the frequency of the radio frequency signal for driving the Mach-Zehnder modulator by continuously adjusting the frequency of the radio frequency signal for driving the Mach-Zehnder modulator.
Drawings
Fig. 1 is a schematic structural diagram of a microwave signal generating apparatus according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of another microwave signal generating apparatus according to an embodiment of the present invention;
FIG. 3 is a schematic illustration of a suppressed carrier double sideband modulated signal output by a Mach-Zehnder modulator;
FIG. 4 is a schematic diagram of the spectrum at various points in FIG. 1;
FIGS. 5a and 5b are schematic frequency spectrums of microwave signals generated when the frequency of the RF driving signal is 10GHz in simulation, respectively;
FIGS. 6a and 6b are schematic frequency spectrums of microwave signals generated when the frequency of the RF driving signal is 15GHz in simulation, respectively;
fig. 7 is a flowchart illustrating a method for generating a microwave signal according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present disclosure more apparent, the technical solutions of the embodiments of the present disclosure will be described clearly and completely with reference to the drawings of the embodiments of the present disclosure. It is to be understood that the described embodiments are only a few embodiments of the present disclosure, and not all embodiments. And the embodiments and features of the embodiments in the present disclosure may be combined with each other without conflict. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the disclosure without any inventive step, are within the scope of protection of the disclosure.
Unless otherwise defined, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure belongs. The use of the word "comprising" or "comprises", and the like, in this disclosure is intended to mean that the elements or items listed before that word, include the elements or items listed after that word, and their equivalents, without excluding other elements or items.
It should be noted that the sizes and shapes of the various figures in the drawings are not to scale, but are merely intended to illustrate the present disclosure. And the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.
The traditional method of generating microwave signals is to use electronic devices to generate microwave signals in the electrical domain. This approach is limited by the inherent electronic bottlenecks of the electronics, such as the small bandwidth of the electrical modulators and demodulators, resulting in an insufficiently high frequency of the generated signal. In addition, due to some electrical characteristics of the electronic device, the problems of large noise of generated microwave signals and the like are easily caused.
The use of optical techniques to generate microwave signals is one way to address the electrical limitations described above. There are three methods for generating microwave signals using optical techniques. The first is to directly modulate the light source generated by the laser, however, the frequency of the signal generated by the direct modulation method is not high enough, and in addition, the output of the directly modulated laser is accompanied by chirp and has poor stability. The second method is to beat the two optical waves at the photodetector by using the frequency difference of the two optical waves. If two optical waves of the beat frequency are generated by two independent lasers, the phase difference between them will result in a large phase noise of the generated microwave signal. The third one is to use the electro-optical modulation and the non-linear effect of the optical fiber, the microwave signal generated by the method has high frequency, is tunable and has low noise, and the method is a commonly used method for generating the microwave signal by using the optical technology at present. For example, 4-fold frequency multiplication is achieved by using a single Mach-Zehnder modulator and driving the Mach-Zehnder modulator with a modulation signal that is biased at a maximum bias point, resulting in a microwave signal with a frequency 4 times the original driving signal frequency of the Mach-Zehnder modulator (ref [1]: O' Reilly J.J., Lane P.M. fiber-supported optical generation and delivery of 60GHz signals [ J ]. Electronics Letters,1994, V30(16): 1329-. In another example, two Mach-Zehnder modulators are cascaded using a tunable optical phase shifter to generate Microwave signals with frequencies 6 times the original signal frequency (reference [2]: Wei Z, Wang R, Pu T, et al. Microwave frequency sequencing generation based on modulator and branched-associated side-filtering [ C ]. International Conference on Microwave and Millimeter Wave technology.2012: 1-3).
Although microwave signals of 4 times and 6 times of the original signal frequency can be generated by utilizing the electro-optical modulation and the nonlinear effect of the optical fiber, in the 4-time-multiplication scheme, the frequency of the generated microwave signals cannot be tunable; in the 6-frequency multiplication scheme, the device becomes complicated and unstable due to the need for a tunable optical phase shifter to cascade the two mach-zehnder modulators.
In order to improve the quality of the generated microwave signal, the invention provides a device and a method for generating the microwave signal, which adopt a single light source and a Mach-Zehnder modulator, and utilize the Stimulated Brillouin Scattering (SBS) effect of an optical fiber to generate the microwave signal with tunable frequency and low phase noise.
The microwave signal generating apparatus provided in the embodiment of the present invention, as shown in fig. 1 and fig. 2, may specifically include: the device comprises a laser 1, a polarization controller 2, a Mach-Zehnder modulator 3, a first circulator 4, a fiber Bragg grating 5, an erbium-doped fiber amplifier 6, a second circulator 7, an optical fiber 8, a coupler 9 and a photoelectric detector 10; wherein,
the laser 1 may be used to generate an optical signal and transmit it as a carrier signal to the polarization controller 2;
the polarization controller 2 is used for adjusting the polarization state of the optical signal and transmitting the optical signal to the Mach-Zehnder modulator 3;
the Mach-Zehnder modulator 3 is used for being driven by the tunable radio-frequency signal and the direct-current signal, modulating the carrier signal, generating a modulation signal and outputting the modulation signal to the first circulator 4;
the first circulator 4 is used for transmitting the modulation signal to the fiber bragg grating 5 and transmitting the reflection modulation signal reflected by the fiber bragg grating 5 to the erbium-doped fiber amplifier 6, wherein the reflection modulation signal is the part of the modulation signal frequency in the reflection spectrum of the fiber bragg grating 5;
the fiber bragg grating 5 is used for transmitting a transmission modulation signal to the coupler 9, wherein the transmission modulation signal is a part of the modulation signal frequency in the transmission spectrum of the fiber bragg grating 5;
the erbium-doped fiber amplifier 6 is used for amplifying the power of the reflected modulation signal and transmitting the power to the second circulator 7 as a pump wave signal, and the power of the pump wave signal is greater than the threshold value of the SBS effect generated by the fiber 8;
the second circulator 7 is used for transmitting a pump wave signal to the optical fiber 8 and transmitting a stokes wave signal generated by the optical fiber 8 to the coupler 9;
the optical fiber 8 is used for being excited by the pump wave signal to generate a Stokes wave signal which is opposite to the transmission direction of the pump wave signal and has at least one Brillouin frequency shift shifted downwards in frequency;
the coupler 9 is used for coupling the stokes wave signal and the transmission modulation signal and then transmitting the coupling signal to the photoelectric detector 10;
the photodetector 10 is used to beat the stokes wave signal and the transmission modulation signal to generate a microwave signal having a frequency that is the difference between the two frequencies.
Specifically, in the embodiment of the present invention, the devices included in the microwave signal generating apparatus may be connected by using pigtails, the generating apparatus uses an all-optical device, generates a microwave signal by using the electro-optical modulation principle of the mach-zehnder modulator 3 and the SBS effect in the optical fiber 8, and has a simple system structure and fewer devices, so that the system has higher stability and is easier to integrate by using the optical and electronic systems. Furthermore, since the frequency of the microwave signal generated by the present invention is in a multiple relationship with the frequency of the radio frequency signal driving the mach-zehnder modulator 3 and the brillouin shift of the optical fiber 8, the frequency of the generated high-frequency microwave signal can be continuously tuned by continuously adjusting the frequency of the radio frequency signal driving the mach-zehnder modulator 3.
Further, in the embodiment of the present invention, the system expandability is good, and the erbium-doped fiber amplifier 6 may be one, or may be a plurality of cascaded amplifiers, so that the pump wave signal can be amplified to a higher frequency, and thus a more multistage SBS effect is excited in the fiber 8 to generate a more multistage stokes wave signal, so that the frequency of the finally generated microwave signal is higher.
In particular, in the embodiment of the present invention, the tunable laser 1 can generate a center frequency f0For example, in computer simulation, the center wavelength of the tunable laser 1 can be set to 1550.38nm, corresponding to the center frequency f0At 193.474THz, the output power may be set to 14.7 dBm. An optical signal output from the laser 1 passes through a polarization controller 2 and is incident on a mach-zehnder modulator 3 as a carrier signal.
The mach-zehnder modulator 3 is an intensity modulator and functions to modulate a radio frequency electrical signal onto a carrier signal into a signal suitable for transmission in a channel. In the present invention, the carrier signal is an optical signal and the channel is an optical fiber 8. The Mach-Zehnder modulator 3 being fed with a frequency fmAnd the tunable radio frequency signal with lower frequency and a direct current signal drive the carrier signal incident to the mach-zehnder modulator 3. The rf signal and the dc signal may be generated by an external signal generator, and therefore, in the microwave signal generating apparatus provided in the embodiment of the present invention, as shown in fig. 1 and fig. 2, the apparatus may further include an rf signal generator 11 and a dc signal generator 12, where the frequency f of the rf signal ismTypically Hz, MHz or GHz, the centre frequency f of the carrier signal0In units of THz. The mach-zehnder modulator 3 has a transmission response diagram in a linear region, and the direct current signal for driving the mach-zehnder modulator 3 is changed, so that the mach-zehnder modulator 3 is biased at different positions and can output modulation signals with different frequency spectrums. The direct current bias point of the mach-zehnder modulator 3 is adjusted to be biased at the minimum transmission point, so that double-sideband modulation of the suppressed carrier signal can be realized, and finally, the modulation signal output from the mach-zehnder modulator 3 is a +1 order sideband signal and a-1 order sideband signal of the suppressed carrier. FIG. 3 shows a simulated suppressed carrier double sideband modulated signal with a +1 order sideband signal having a frequency f0+fmAnd the frequency of the-1 st order sideband signal is f0-fmThe power is 20dB higher than the power of the carrier signal.
Alternatively, in the embodiment of the present invention, as shown in fig. 1 and 2, the first circulator 4 may include 1 port, 2 ports, and 3 ports, the transmission sequence of the signal in the first circulator 4 is as shown by arrows in fig. 1 and 2, and the fiber bragg grating 5 is connected to the 2 ports of the first circulator 4. The port 1 of the first circulator 4 is used for receiving the modulation signal and transmitting the modulation signal to the port 2; the port 2 of the first circulator 4 is used for transmitting the modulation signal to the fiber bragg grating 5 and transmitting the reflection modulation signal reflected by the fiber bragg grating 5 to the port 3; the port 3 of the first circulator 4 is used to transmit the reflected modulated signal to the erbium doped fiber amplifier 6.
Specifically, the modulated signal output by the mach-zehnder modulator 3 and suppressing the carrier double-sideband enters the first circulator 4 through the port 1 of the first circulator 4, and enters the fiber bragg grating 5 located in the upper branch from the port 2 of the first circulator 4. The fiber bragg grating 5 has reflection and transmission characteristics, and divides the modulation signal output by the mach-zehnder modulator 3 into two paths, wherein the modulation signal part with the frequency in the transmission spectrum of the fiber bragg grating 5, namely, the transmission modulation signal, reaches a point b in fig. 1 and 2 through the fiber bragg grating 5, and the modulation signal part with the frequency in the reflection spectrum of the fiber bragg grating 5, namely, the reflection modulation signal, is reflected back by the fiber bragg grating 5, passes through the first circulator 4, then is incident to the lower branch circuit, and reaches a point c in fig. 1 and 2.
Specifically, the central wavelength of the transmission spectrum and the central wavelength of the reflection spectrum of the fiber bragg grating 5 can be adjusted, so that the +1 order sideband signal and the-1 order sideband signal of the modulation signal for suppressing the carrier double sideband respectively fall in the transmission spectrum and the reflection spectrum of the fiber bragg grating 5. For example, if the central wavelength of the transmission spectrum of the fiber bragg grating 5 is set to be 1550.598nm, the frequency of the +1 order sideband signal is within the transmission spectrum of the fiber bragg grating 5, and the frequency of the-1 order sideband signal is within the reflection spectrum of the fiber bragg grating 5, so that the fiber bragg grating 5 transmits the +1 order sideband signal to the point b in fig. 1 and 2, and the-1 order sideband signal is reflected by the fiber bragg grating 5, enters the first circulator 4 from the port 2 of the first circulator 4, passes through the port 3 of the first circulator 4, enters the lower branch, and reaches the point c in fig. 1 and 2. Or, the central wavelength of the reflection spectrum of the fiber bragg grating 5 may be set to be 1550.598nm, and then the frequency of the +1 order sideband signal is within the reflection spectrum of the fiber bragg grating 5, and the frequency of the-1 order sideband signal is within the transmission spectrum of the fiber bragg grating 5, so that the fiber bragg grating 5 transmits the-1 order sideband signal to the point b in fig. 1 and 2, and the +1 order sideband signal is reflected by the fiber bragg grating 5, enters the first circulator 4 from the port 2 of the first circulator 4, passes through the port 3 of the first circulator 4, and then enters the lower branch to reach the point c in fig. 1 and 2. Hereinafter, the fiber Bragg grating 5 will be described by taking an example in which +1 order sideband signals are transmitted and-1 order sideband signals are reflected.
Specifically, the-1 order sideband signal incident to the lower branch is amplified by the power of the erbium-doped fiber amplifier 6, and when the power of the reflected modulation signal is amplified to be large enough to reach the threshold value of the SBS effect generated by the fiber 8, the signal can be used as a pump wave signal to excite the SBS effect in the fiber 8 to generate at least one Brillouin frequency shift v opposite to the transmission direction of the pump wave signal and with the frequency shifted downwardsBThe stokes wave signal of (a).
In particular, in an embodiment of the present invention, the brillouin frequency shift v of the SBS effect of the optical fiber 8BThe size being determined by the type of fibre 8, the Brillouin frequency shift v being determined using different types of fibre 8BThere will be a change, Brillouin frequency shift vBBasically around 10GHz-11 GHz. Alternatively, in the embodiment of the present invention, the optical fiber 8 may specifically adopt a single mode fiber or a non-zero dispersion shifted fiber or a dispersion shifted fiber.
For example, in the lower branch, the-1 order sideband signal can be incident into the dispersion-shifted fiber with a length of 4km at a power of 15dBm output by an erbium-doped fiber amplifier 6, so that the-1 order sideband signal can be used as a pump wave signal to excite the SBS effect in the dispersion-shifted fiber.
Specifically, the SBS process in the optical fiber 8 can be regarded as a nonlinear process in which the pump wave, the stokes wave, and the acoustic wave interact with each other. A complete theoretical analysis of the SBS process requires solving differential equations for the three. However, in the frequency domain, when the frequency difference between the pump wave and the signal transmitted in reverse thereto and the relative frequency difference of the SBS frequency shift do not exceed the SBS gain bandwidth, the finite phonon damping time is negligible, and in this simplified condition, the SBS process can be analyzed by the intensity coupling equation describing both the pump wave and the stokes wave, as shown in the following equation (1-1):
in the formula IPu(z, t) and ISt(z, t) represent the intensity of the pump wave and the Stokes wave, respectively, g (v) is the SBS gain, and α is the loss system of the optical fiber 8The propagation velocity of the light waves, v, in the optical fiber 8. The boundary conditions of the above formula (1-1) are:
IPu(0,t)＝IC
ISt(L,t)＝Im0+Im1cos(ωt) (1-2)
where L is the length of the optical fiber 8. Here, the stokes wave in the initial condition is regarded as an oscillation with a small amplitude, and thus the solution of the above equation (1-1) is shifted to the frequency domain.
When solving the time domain solution of the above equation, it can be written as:
IPu(z,t)＝IP0(z)+Re{IP(z)exp(jωt)}
ISt(z,t)＝IS0(z)+Re{IS(z)exp(jωt)} (1-3)
in the formula IP0(z) and Is0(z) is a stable solution of formula (3-4) and can be solved by the targeting method.
In small signal modulation (I)m0＞＞Im1) By substituting formula (1-3) into formula (1-1), formula (1-1) can be simplified as follows:
under normal conditions, the pump wave and the Stokes wave satisfy IC＞＞Im0The second equation in equations (1-4) can be directly solved, and a closed form solution about the intensity of the stokes wave can be obtained in the frequency domain, as shown in equations (1-5) below:
in the formula (1-5), g (v) is an SBS gain expression and can be written as:
in the formula, uBRepresenting the SBS frequency shift, gBAnd [ Delta ] vBRepresenting the SBS peak gain and SBS gain bandwidth, respectively. v represents the relative frequency with respect to the frequency at the SBS gain peak. When the length L and the position z of the optical fiber 8 are determined, the intensity or power of the stokes wave can be directly obtained from the equations (1-5). Further, the optical field expression E of the Stokes wave can be obtainedSt(t)。
Under small signal modulation conditions, the output optical field expression of the mach-zehnder modulator 3 may be written as:
Eout(t)＝A[J-1(m)cos(2π(f0-fm)t)-J1(m)cos(2π(f0+fm)t)] (1-7)
in the formula Jn(. DEG) represents a Bessel function of order n, m is the modulation depth, f0Frequency of light source carrier wave, fmRepresenting the frequency of the radio frequency signal driving the mach-zehnder modulator 3. Optical field expression E of upper sideband of modulation signal1t(t) can be directly obtained from the formula (1-7) when it and the lower sideband are subjected to the SBS process to produce the secondary Stokes wave ESt(t) beating in the photodetector 10, the intensity of the output photocurrent can be expressed as:
I∝|E1t(t)+Est(t)|2 (1-8)
its frequency can be written as:
f＝2(fm+υB) (1-9)
specifically, in the embodiment of the present invention, the-1 st order sideband signal may have a two-stage SBS effect occurring in the optical fiber 8, i.e., the signal finally output from the second circulator 7 is shifted down by two brillouin frequency shifts with respect to the pump wave signal frequency. At this time, optionally, in the embodiment of the present invention, the second circulator 7 may adopt a two-in two-out circulator, as shown in fig. 1, and may specifically include 1 port, 2 ports, 3 ports, and 4 ports, and the signal is transmitted in the second circulatorThe transmission sequence in 7 is shown by the arrows in fig. 1, and the two ends of the optical fiber 8 are respectively connected to the ports 2 and 3 of the second circulator 7 to form a loop. The pump wave signal of the lower branch, i.e., -1 order sideband signal, passes through the port 1 of the second circulator 7 and enters the optical fiber 8 from the port 2, so that the-1 order sideband signal is used as the pump wave signal to excite the SBS effect in the optical fiber 8, and a V frequency shift opposite to the transmission direction of the-1 order sideband signal and downward is generated in the optical fiber 8BOf a first-order Stokes wave signal having a center frequency f0-fm-vB. The power of the-1 order sideband signal is mostly transferred into the first order stokes wave signal. The first-order stokes wave signal is transmitted in the reverse direction in the optical fiber 8, so that the first-order stokes wave signal enters from the port 2 of the second circulator 7, passes through the port 3 and then enters the optical fiber 8 again. When the power of the first-stage Stokes wave signal is the same as the power of the optical fiber 8, the SBS effect can be excited again in the optical fiber 8 to generate a second-stage Stokes wave signal with the transmission direction opposite to that of the first-stage Stokes wave signal, and the frequency of the second-stage Stokes wave signal is shifted downwards by v relative to the first-stage Stokes wave signalBSo that the center frequency of the second-order Stokes wave is f0-fm-2vBThe frequency of the second-order stokes wave signal is shifted down by a 2-fold brillouin frequency shift with respect to the pump wave signal. The second-order stokes wave signal passes through the 3 ports of the second circulator 7 and then is output from the 4 ports of the second circulator 7 to the point d.
Alternatively, in the embodiment of the present invention, the-1 st order sideband signal may also have a first order SBS effect occurring in the optical fiber 8, i.e., the signal finally output from the second circulator 7 is shifted down by one brillouin frequency shift with respect to the pump wave signal frequency. At this time, optionally, in the embodiment of the present invention, as shown in fig. 2, the second circulator 7 may also include 1 port, 2 ports, and 3 ports, a transmission sequence of signals in the second circulator 7 is shown by arrows in fig. 2, and both ends of the optical fiber 8 are respectively connected to the 2 ports of the second circulator 7 to form a loop. The pump wave signal of the lower branch, i.e., -1 order sideband signal, passes through port 1 of the second circulator 7 and enters the optical fiber 8 from port 2, so that the-1 order sideband signal is used as the pump wave signal to excite the SBS effect in the optical fiber 8 and generate in the optical fiber 8A frequency shift v opposite to the transmission direction of the-1 st order sideband signalBOf a first-order Stokes wave signal having a center frequency f0-fm-vB. The power of the-1 order sideband signal is mostly transferred into the first order stokes wave signal. The first-order stokes wave signal is transmitted in the reverse direction in the optical fiber 8, so that the first-order stokes wave signal enters from the port 2 of the second circulator 7 and is output to the point d after passing through the port 3.
Specifically, for example, when the lower branch generates the second-stage SBS effect, the frequency at the b point of the upper branch is f0+fmThe +1 order sideband signal and the frequency f generated by the lower branch after passing through the optical fiber 80-fm-2vBAfter passing through a coupler 9, the second-order stokes wave signal is incident into a photodetector 10 for beat frequency, and a microwave signal with the frequency difference of the two is generated, wherein the frequency is f-2 (f)m+vB). Fig. 4 shows a schematic spectrum diagram at points a, b, c, d in fig. 1. As shown in fig. 1 and 2, a spectrum analyzer 13 may be externally connected to the output end of the photodetector 10 to observe the power spectrum of the generated microwave signal. By adjusting the frequency of the radio frequency signal driving the mach-zehnder modulator 3 and the output power of the erbium-doped fiber amplifier 6, a continuously tunable high-frequency microwave signal can be obtained.
The simulation results obtained by verifying the microwave signal generating device provided by the embodiment of the present invention through computer simulation are shown in fig. 5a to 6 b. In the simulation, as shown in FIG. 5a, f is setm10GHz Brillouin frequency shift vBSetting the frequency to 10GHz, obtaining a microwave signal with the frequency of 40 GHz; compared with the laser 1 shown in fig. 5a, which adopts an ideal line width, the line width of the laser 1 is adjusted to be 100KHz, and as shown in fig. 5b, the noise platform for obtaining the microwave signal is improved. As shown in fig. 6a, set fm15GHz Brillouin frequency shift vBSetting the frequency to 10GHz, a microwave signal with the frequency of 50GHz can be obtained; compared with the laser 1 shown in fig. 6a adopting an ideal line width, the line width of the laser 1 is adjusted to be 100KHz, and as shown in fig. 6b, the noise platform for obtaining the microwave signal is improved. Based on the simulation results, the method can be seenThe noise floor of the finally generated microwave signal is in positive correlation with the line width of the laser 1, and the narrower the optical signal line width output by the laser is, the smaller the noise of the finally generated microwave signal is.
Based on the same inventive concept, the embodiment of the present invention further provides a method for generating a microwave signal, and since the principle of the method for generating a microwave signal to solve the problem is similar to that of the aforementioned generating apparatus, the implementation of the method for generating a microwave signal can be referred to the implementation of the apparatus, and repeated details are not repeated.
The method for generating a microwave signal according to the embodiment of the present invention, as shown in fig. 7, may specifically include the following steps:
and S1, generating an optical signal by the laser and transmitting the optical signal to the polarization controller as a carrier signal.
And S2, the polarization controller is used for adjusting the polarization state of the optical signal and transmitting the optical signal to the Mach-Zehnder modulator.
And S3, the Mach-Zehnder modulator is driven by the tunable radio-frequency signal and the direct-current signal, modulates the carrier signal, generates a modulation signal and outputs the modulation signal to the first circulator.
Specifically, the direct current signal driving the mach-zehnder modulator may be adjusted to position the bias point of the mach-zehnder modulator at the minimum transmission point, and the double sidebands of the carrier signal are suppressed, so that the obtained modulation signal includes a +1 order sideband signal and a-1 order sideband signal of the carrier signal.
And S4, the first circulator transmits the modulation signal to the fiber Bragg grating.
S5, the fiber Bragg grating transmits the transmission modulation signal of the modulation signal frequency in the fiber Bragg grating transmission spectrum to the coupler, and reflects the reflection modulation signal of the modulation signal frequency in the fiber Bragg grating reflection spectrum back to the first circulator.
Specifically, the transmission and reflection spectra of the fiber bragg grating may be controlled such that the frequency of the +1 order sideband signal is within the fiber bragg grating transmission spectrum and the frequency of the-1 order sideband signal is within the fiber bragg grating reflection spectrum, the fiber bragg grating transmitting the +1 order sideband signal to the coupler and reflecting the-1 order sideband signal back to the first circulator. Alternatively, the transmission and reflection spectra of the fiber bragg grating may be controlled such that the frequency of the +1 order sideband signal is within the fiber bragg grating reflection spectrum and the frequency of the-1 order sideband signal is within the fiber bragg grating transmission spectrum, the fiber bragg grating transmitting the-1 order sideband signal to the coupler and reflecting the +1 order sideband signal back to the first circulator.
S6, the first circulator transmits the reflection modulation signal to the erbium-doped fiber amplifier.
And S7, amplifying the power of the reflected modulation signal by the erbium-doped fiber amplifier, and transmitting the power of the reflected modulation signal to the second circulator as a pump wave signal, wherein the power of the pump wave signal is greater than the threshold of the SBS effect generated by the fiber.
S8, the second circulator transmits the pump wave signal to the optical fiber.
And S9, the optical fiber is excited by the pump wave signal to generate a Stokes wave signal which is opposite to the transmission direction of the pump wave signal and is shifted down in frequency by at least one Brillouin frequency shift, and the Stokes wave signal is transmitted to the second circulator.
Specifically, the optical fiber is excited by the pump wave signal to generate a first-stage Stokes wave signal which is opposite to the transmission direction of the pump wave signal and has the frequency shifted down by one Brillouin frequency shift, and the first-stage Stokes wave signal is transmitted back to the second circulator; then, the first-order Stokes wave signals are transmitted to the optical fiber by the second circulator; then, the optical fiber is excited by the first-order Stokes wave signal to generate a second-order Stokes wave signal which is opposite to the transmission direction of the first-order Stokes wave signal and is shifted down in frequency by one Brillouin frequency shift, and the second-order Stokes wave signal is transmitted to the second circulator. Or the optical fiber is excited by the pump wave signal to generate a first-order Stokes wave signal which is opposite to the transmission direction of the pump wave signal and is shifted down by one Brillouin frequency shift in frequency, and the first-order Stokes wave signal is transmitted back to the second circulator.
And S10, the second circulator transmits the Stokes wave signal generated by the optical fiber to the coupler.
And S11, the coupler couples the Stokes wave signal and the transmission modulation signal and transmits the coupled Stokes wave signal and the transmission modulation signal to the photodetector.
S12, the photoelectric detector beats the Stokes wave signal and the transmission modulation signal to generate a microwave signal with the frequency difference between the two frequencies.
In the method provided by the embodiment of the present invention, the frequency of the radio frequency signal driving the mach-zehnder modulator may be specifically adjusted, so as to obtain the tunable microwave signal.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (16)
1. An apparatus for generating a microwave signal, comprising: the device comprises a laser, a polarization controller, a Mach-Zehnder modulator, a first circulator, a fiber Bragg grating, an erbium-doped fiber amplifier, a second circulator, an optical fiber, a coupler and a photoelectric detector; wherein,
the laser is used for generating an optical signal and transmitting the optical signal to the polarization controller as a carrier signal;
the polarization controller is used for adjusting the polarization state of the optical signal and transmitting the optical signal to the Mach-Zehnder modulator;
the Mach-Zehnder modulator is used for being driven by a tunable radio-frequency signal and a direct-current signal, modulating the carrier signal, generating a modulation signal and outputting the modulation signal to the first circulator;
the first circulator is used for transmitting the modulation signal to the fiber Bragg grating and transmitting a reflection modulation signal reflected by the fiber Bragg grating to the erbium-doped fiber amplifier, and the reflection modulation signal is a part of the modulation signal frequency in the reflection spectrum of the fiber Bragg grating;
the fiber Bragg grating is used for transmitting a transmission modulation signal to the coupler, wherein the transmission modulation signal is the part of the modulation signal frequency in the transmission spectrum of the fiber Bragg grating;
the erbium-doped fiber amplifier is used for amplifying the power of the reflection modulation signal and transmitting the power of the reflection modulation signal to the second circulator as a pump wave signal, and the power of the pump wave signal is greater than the threshold value of the SBS effect generated by the fiber;
the second circulator is used for transmitting the pump wave signal to the optical fiber and transmitting a Stokes wave signal generated by the optical fiber to the coupler;
the optical fiber is used for being excited by the pump wave signal to generate the Stokes wave signal which is opposite to the transmission direction of the pump wave signal and is shifted in frequency by at least one Brillouin frequency shift;
the coupler is used for coupling the Stokes wave signal and the transmission modulation signal and then transmitting the coupling to the photoelectric detector;
and the photoelectric detector is used for beating the Stokes wave signal and the transmission modulation signal and generating a microwave signal with the frequency of the difference between the two frequencies.
2. A microwave signal generation apparatus in accordance with claim 1, wherein the modulation signal generated by the mach-zehnder modulator comprises +1 order sideband signal and-1 order sideband signal of the carrier signal.
3. A microwave signal generating apparatus as claimed in claim 2, wherein the frequency of the +1 order sideband signal is within the fiber bragg grating transmission spectrum, and the transmission modulation signal is the +1 order sideband signal;
the frequency of the-1 order sideband signal is in the fiber Bragg grating reflection spectrum, and the reflection modulation signal is the-1 order sideband signal.
4. A microwave signal generating apparatus as claimed in claim 2, wherein the frequency of the +1 order sideband signal is within the fiber bragg grating reflection spectrum, and the reflection modulation signal is the +1 order sideband signal;
the frequency of the-1 order sideband signal is in the transmission spectrum of the fiber Bragg grating, and the transmission modulation signal is the-1 order sideband signal.
5. The apparatus of any of claims 1-4, wherein the second circulator includes 1 port, 2 ports, 3 ports, and 4 ports, and the optical fiber is connected between the 2 ports and the 3 ports of the second circulator;
the port 1 of the second circulator is used for receiving the pump wave signal and transmitting the pump wave signal to the port 2;
the port 2 of the second circulator is used for transmitting the pump wave signal into the optical fiber and transmitting a first-order Stokes wave signal generated by the optical fiber to the port 3; the transmission directions of the first-order Stokes wave signal and the pumping wave signal are opposite, and the frequency is shifted down by one Brillouin frequency shift;
the 3 ports of the second circulator are used for transmitting the primary Stokes wave signals into the optical fiber and transmitting the secondary Stokes wave signals generated by the optical fiber to the 4 ports; the transmission directions of the secondary Stokes wave signals and the primary Stokes wave signals are opposite, and the frequency is shifted down by one Brillouin frequency shift;
the 4 ports of the second circulator are used for transmitting the second-order Stokes wave signal to the coupler.
6. A microwave signal generating apparatus as claimed in any one of claims 1 to 4, wherein said second circulator includes 1 port, 2 ports and 3 ports, and said optical fiber is connected to 2 ports of said second circulator;
the port 1 of the second circulator is used for receiving the pump wave signal and transmitting the pump wave signal to the port 2;
the port 2 of the second circulator is used for transmitting the pump wave signal into the optical fiber and transmitting a first-order Stokes wave signal generated by the optical fiber to the port 3; the transmission directions of the first-order Stokes wave signal and the pumping wave signal are opposite, and the frequency is shifted down by one Brillouin frequency shift;
the 3 ports of the second circulator are used for transmitting the first-order Stokes wave signal to the coupler.
7. The apparatus for generating a microwave signal according to any one of claims 1 to 4, wherein the first circulator includes 1 port, 2 ports, and 3 ports, and the fiber Bragg grating is connected to the 2 ports of the first circulator;
the port 1 of the first circulator is used for receiving the modulation signal and transmitting the modulation signal to the port 2;
the 2 ports of the first circulator are used for transmitting the modulation signal to the fiber Bragg grating and transmitting a reflection modulation signal reflected by the fiber Bragg grating to the 3 ports;
and 3 ports of the first circulator are used for transmitting the reflection modulation signals to the erbium-doped fiber amplifier.
8. A microwave signal generation apparatus according to any one of claims 1 to 4, wherein the erbium-doped fiber amplifier is one, or a plurality of erbium-doped fiber amplifiers are cascaded.
9. A microwave signal generating apparatus according to any one of claims 1 to 4, wherein the optical fiber comprises: single mode fibers or non-zero dispersion shifted fibers or dispersion shifted fibers.
10. A method of generating a microwave signal, comprising:
the laser generates an optical signal and transmits the optical signal to the polarization controller as a carrier signal;
the polarization controller is used for adjusting the polarization state of the optical signal and transmitting the optical signal to the Mach-Zehnder modulator;
the Mach-Zehnder modulator is driven by a tunable radio-frequency signal and a direct-current signal, modulates the carrier signal, generates a modulation signal and outputs the modulation signal to the first circulator;
the first circulator transmits the modulation signal to a fiber Bragg grating;
the fiber Bragg grating transmits the transmission modulation signal with the modulation signal frequency within the fiber Bragg grating transmission spectrum to the coupler and reflects the reflection modulation signal with the modulation signal frequency within the fiber Bragg grating reflection spectrum back to the first circulator;
the first circulator transmits the reflection modulation signal to an erbium-doped fiber amplifier;
the erbium-doped fiber amplifier amplifies the power of the reflection modulation signal and transmits the power to the second circulator as a pump wave signal, and the power of the pump wave signal is greater than the threshold of the SBS effect generated by the fiber;
the second circulator transmits the pump wave signal to the optical fiber;
the optical fiber is excited by the pump wave signal to generate a SBS effect, generates a Stokes wave signal which is opposite to the transmission direction of the pump wave signal and is shifted in frequency by at least one Brillouin frequency shift, and transmits the Stokes wave signal to the second circulator;
the second circulator transmits a Stokes wave signal generated by the optical fiber to a coupler;
the coupler couples the Stokes wave signal and the transmission modulation signal and then transmits the coupling Stokes wave signal and the transmission modulation signal to the photoelectric detector;
and the photoelectric detector beats the Stokes wave signal and the transmission modulation signal to generate a microwave signal with the frequency of the difference between the two frequencies.
11. The method for generating a microwave signal according to claim 10, wherein the mach-zehnder modulator is driven by a tunable rf signal and a dc signal, modulates the carrier signal, generates a modulation signal, and outputs the modulation signal to the first circulator, and specifically includes:
and adjusting a direct current signal for driving the Mach-Zehnder modulator to enable a bias point of the Mach-Zehnder modulator to be positioned at a minimum transmission point, and suppressing a carrier of the modulation signal, wherein the obtained modulation signal comprises a +1 order sideband signal and a-1 order sideband signal of the modulation signal.
12. The method for generating a microwave signal according to claim 11, wherein the fiber bragg grating transmits the transmission modulation signal having the modulation signal frequency within the fiber bragg grating transmission spectrum to the coupler and reflects the reflection modulation signal having the modulation signal frequency within the fiber bragg grating reflection spectrum back to the first circulator, specifically comprising:
controlling the transmission spectrum and the reflection spectrum of the fiber Bragg grating to enable the frequency of the +1 order sideband signal to be within the transmission spectrum of the fiber Bragg grating and the frequency of the-1 order sideband signal to be within the reflection spectrum of the fiber Bragg grating;
the fiber Bragg grating transmits the +1 order sideband signal to the coupler and reflects the-1 order sideband signal back to the first circulator.
13. The method for generating a microwave signal according to claim 11, wherein the fiber bragg grating transmits the transmission modulation signal having the modulation signal frequency within the fiber bragg grating transmission spectrum to the coupler and reflects the reflection modulation signal having the modulation signal frequency within the fiber bragg grating reflection spectrum back to the first circulator, specifically comprising:
controlling the transmission spectrum and the reflection spectrum of the fiber Bragg grating to enable the frequency of the +1 order sideband signal to be within the fiber Bragg grating reflection spectrum and the frequency of the-1 order sideband signal to be within the fiber Bragg grating transmission spectrum;
the fiber Bragg grating transmits the-1 order sideband signal to the coupler and reflects the +1 order sideband signal back to the first circulator.
14. A method of generating a microwave signal according to any of claims 10-13, wherein the optical fiber is excited by the pump wave signal to an SBS effect, generates a stokes wave signal that is opposite to the direction of transmission of the pump wave signal and shifted in frequency by at least one brillouin shift, and transmits to the second circulator, in particular comprising:
the optical fiber is excited by the pump wave signal to generate a SBS effect, generates a first-order Stokes wave signal which is opposite to the transmission direction of the pump wave signal and is shifted down by one Brillouin frequency shift in frequency, and transmits the first-order Stokes wave signal back to the second circulator;
the second circulator transmits the first-order stokes wave signal to the optical fiber;
the optical fiber is excited again by the SBS effect by the primary Stokes wave signal, generates a secondary Stokes wave signal which is opposite to the transmission direction of the primary Stokes wave signal and is shifted down in frequency by one Brillouin frequency shift, and transmits the secondary Stokes wave signal to the second circulator so that the second circulator transmits the secondary Stokes wave signal to the coupler.
15. A method of generating a microwave signal according to any of claims 10-13, wherein the optical fiber is excited by the pump wave signal to an SBS effect, generates a stokes wave signal that is opposite to the direction of transmission of the pump wave signal and shifted in frequency by at least one brillouin shift, and transmits to the second circulator, in particular comprising:
the optical fiber is excited by the pump wave signal to generate a SBS effect, generates a first-order Stokes wave signal which is opposite to the transmission direction of the pump wave signal and is shifted down in frequency by one Brillouin frequency shift, and transmits the first-order Stokes wave signal back to the second circulator, so that the second circulator transmits the first-order Stokes wave signal to the coupler.
16. A method of generating a microwave signal in accordance with any of claims 10 to 13, further comprising:
adjusting the frequency of the radio frequency signal driving the mach-zehnder modulator so as to obtain a tunable microwave signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111595088.2A CN114389698B (en) | 2021-12-24 | 2021-12-24 | Microwave signal generating device and method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111595088.2A CN114389698B (en) | 2021-12-24 | 2021-12-24 | Microwave signal generating device and method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN114389698A true CN114389698A (en) | 2022-04-22 |
| CN114389698B CN114389698B (en) | 2024-05-14 |
Family
ID=81197816
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111595088.2A Active CN114389698B (en) | 2021-12-24 | 2021-12-24 | Microwave signal generating device and method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114389698B (en) |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104993358A (en) * | 2015-07-07 | 2015-10-21 | 中国科学院半导体研究所 | Single-sideband optical carrier microwave signal generating device based on stimulated Brillouin scattering |
| CN105607302A (en) * | 2016-03-21 | 2016-05-25 | 中国科学院半导体研究所 | Tunable single-passband microwave photonic filter based on Brillouin optical carrier recovery |
| CN106027152A (en) * | 2016-05-12 | 2016-10-12 | 西安电子科技大学 | Method for generating 120GHz millimeter waves based on octuple frequency of Mach-Zehnder modulator |
| CN108988105A (en) * | 2018-07-27 | 2018-12-11 | 南京邮电大学 | A kind of generation device and its method of the super flat microwave frequency comb in high power broadband |
| CN109450540A (en) * | 2018-08-10 | 2019-03-08 | 电子科技大学 | A kind of tunable dual-passband microwave photon filter realization device and method |
| CN111141318A (en) * | 2020-01-17 | 2020-05-12 | 安捷光通科技成都有限公司 | Brillouin optical time domain clash type distributed optical fiber sensor |
| CN113078545A (en) * | 2021-03-30 | 2021-07-06 | 电子科技大学 | Tunable dual-frequency photoelectric oscillator device based on stimulated Brillouin scattering |
-
2021
- 2021-12-24 CN CN202111595088.2A patent/CN114389698B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104993358A (en) * | 2015-07-07 | 2015-10-21 | 中国科学院半导体研究所 | Single-sideband optical carrier microwave signal generating device based on stimulated Brillouin scattering |
| CN105607302A (en) * | 2016-03-21 | 2016-05-25 | 中国科学院半导体研究所 | Tunable single-passband microwave photonic filter based on Brillouin optical carrier recovery |
| CN106027152A (en) * | 2016-05-12 | 2016-10-12 | 西安电子科技大学 | Method for generating 120GHz millimeter waves based on octuple frequency of Mach-Zehnder modulator |
| CN108988105A (en) * | 2018-07-27 | 2018-12-11 | 南京邮电大学 | A kind of generation device and its method of the super flat microwave frequency comb in high power broadband |
| CN109450540A (en) * | 2018-08-10 | 2019-03-08 | 电子科技大学 | A kind of tunable dual-passband microwave photon filter realization device and method |
| CN111141318A (en) * | 2020-01-17 | 2020-05-12 | 安捷光通科技成都有限公司 | Brillouin optical time domain clash type distributed optical fiber sensor |
| CN113078545A (en) * | 2021-03-30 | 2021-07-06 | 电子科技大学 | Tunable dual-frequency photoelectric oscillator device based on stimulated Brillouin scattering |
Also Published As
| Publication number | Publication date |
|---|---|
| CN114389698B (en) | 2024-05-14 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US6535328B2 (en) | Methods and devices based on brillouin selective sideband amplification | |
| CN108199776B (en) | Microwave photon up-conversion device and method based on photoelectric oscillator | |
| Zeng et al. | Investigation of phase-modulator-based all-optical bandpass microwave filter | |
| Wiberg et al. | Microwave-photonic frequency multiplication utilizing optical four-wave mixing and fiber Bragg gratings | |
| US9698913B2 (en) | System and method for distortion correction in phase-encoded photonic links | |
| US20080310464A1 (en) | Device for Generating and Modulating a High-Frequency Signal | |
| Morrison et al. | Tunable microwave photonic notch filter using on-chip stimulated Brillouin scattering | |
| Schneider et al. | Generation of millimetre-wave signals by stimulated Brillouin scattering for radio over fibre systems | |
| US20070139762A1 (en) | Translation of individual and entangled states of light by four-wave mixing in fibers | |
| US11609474B2 (en) | Terahertz signal generation apparatus and terahertz signal generation method using the same | |
| Zhu et al. | Optical millimeter-wave signal generation by frequency quadrupling using one dual-drive Mach–Zehnder modulator to overcome chromatic dispersion | |
| CN107947867B (en) | Single-sideband spectrum generation device and method based on multi-frequency phase modulation | |
| US10897313B2 (en) | Apparatus and method for reducing distortion of an optical signal | |
| JP2018169487A (en) | Phase conjugate light generator and optical communication system, and phase conjugate light generation method | |
| Tang et al. | Inline frequency-non-degenerate phase-sensitive fibre parametric amplifier for fibre-optic communication | |
| Junker et al. | A comparative test of Brillouin amplification and erbium-doped fiber amplification for the generation of millimeter waves with low phase noise properties | |
| CN114389698B (en) | Microwave signal generating device and method | |
| Mohamed et al. | Efficient photonic generation of millimeter-waves using optical frequency multiplication in radio-over-fiber systems | |
| CN114336227A (en) | Microwave signal generating device based on low-distortion dissipative Kerr soliton | |
| Cheng et al. | 20 GHz self‐oscillating parametric optical frequency comb generator using an electroabsorption modulated laser based dual‐loop optoelectronic oscillator | |
| Alom et al. | Photonic mixer incorporating all-optical microwave frequency generator based on stimulated Brillouin scattering using single laser source | |
| Shin et al. | Low phase-noise 40 GHz optical pulses from a self-starting electroabsorption-modulator-based optoelectronic oscillator | |
| Baskaran et al. | Photonic generation of microwave pulses using Stimulated Brillouin Scattering (SBS)-based carrier processing and data transmission for Radio over Fiber (RoF) systems | |
| CN114337833B (en) | IM-DD OFDM transmission system based on OPC dispersion compensation | |
| Junker et al. | High quality millimeter wave generation via stimulated Brillouin scattering |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |