CN104269732A - Method and device for generating microwave signal based on Brillouin amplification multi-wavelength laser device - Google Patents

Abstract

The invention discloses a method and a device for generating a microwave signal based on a Brillouin amplification multi-wavelength laser device. The device comprises a multi-wavelength laser device unit, a filter, a coupler, a photoelectric detector and the like, wherein the multi-wavelength laser device unit comprises a laser device unit, a coupler unit, an amplifier unit, a circulator unit, an optical fiber unit, a polarization controller unit and an isolator unit. The device and the method for generating the microwave signal not only can generate a high-frequency microwave signal and but also can acquire a multi-bandwidth tunable microwave signal. The device disclosed by the invention does not need an electronic device, so that the probability of electromagnetic interference and the like is greatly reduced; furthermore, the device has the advantages of low cost and simple structure.

Description

Based on the method and apparatus that the microwave signal of Brillouin amplification multiple-wavelength laser produces

Technical field

The present invention relates to the method and apparatus that a kind of microwave signal based on Brillouin amplification multiple-wavelength laser produces, be mainly used in the technical fields such as wireless sense network, optical fiber telecommunications system and Microwave photonics.

Background technology

Microwave signal source is as one of elemental device in microwave system, and its performance directly determines the service behaviour of system.At present, microwave signal source has been widely used in the modernization information systems such as microwave communication, radar guidance, remote sensing observing and controlling, electronic countermeasures, and along with developing rapidly of information technology, the microwave source of high-quality becomes the key of getting the upper hand of; Enriching constantly along with multimedia service on the other hand, the frequency spectrum resource taken constantly rises, the processing limit of electronic device has been approached based on digital electronic technology, there is the problem such as the restriction of bandwidth and the electronic bottleneck of switching system, the difficulty of further raising device processes speed is increasing, therefore, the requirement of setting up all-optical information system is proposed.Under this background, Microwave photonics occurs and progressively becomes the interdisciplinary technology that has merged microwave technology and photon technology, not only can overcome insurmountable electronic bottleneck problem in conventional radio frequency microwave system, and provide powerful support for contemporary high speed information network construction.Therefore, optical technology demonstrates the incomparable advantage of electronic technology in the generation etc. of microwave signal, and the superiority bandwidth making full use of optical technology realizes high speed full optical information technology and just seems extremely important.In fibre system, the microwave signal of transmission can be subject to the impact of the factors such as optical fiber dispersion and distortion and distortion occur, and the higher impact be subject to of microwave frequency is larger.Therefore, the method obtaining at present microwave signal mainly concentrates in the methods such as the method for optical heterodyne and microwave frequency shift modulation.In the method for microwave frequency shift modulation, must high-speed modulator etc. be used, limit the generation of high-frequency microwave signal, and expensive.The patent of invention (application number 200810061240.7) waiting proposition as bright in profound scholar, adopts the method for microwave source and electrooptic modulator to obtain the microwave signal of 11GHz.Some scholars propose and pass through Brillouin scattering, the scheme of microwave signal is obtained in conjunction with light heterodyne method, as the patent of invention (application number 200910155858.4) that Fu Jiaojiao etc. proposes, king is as just waited patent of invention (application number 201210341950.1) proposed, the patent of invention (application number 201410093542.8) of Zhou Feng etc., the difference frequency of Brillouin scattering and pump light is adopted to obtain microwave signal, there is certain use value, but, the tunable range producing microwave signal is less, and systematic comparison is complicated, limit its application in fields such as radars.

Summary of the invention

The present invention seeks to: the above-mentioned shortcoming overcoming prior art, in order to obtain the tunable microwave signal of high-frequency wideband, the invention provides the method and apparatus that a kind of adjustable microwave signal based on Brillouin amplification multiple-wavelength laser produces, the apparatus and method proposed can not only produce high-frequency microwave signal, and can obtain the tunable microwave signal source of bandwidth; The advantages such as meanwhile, it is low that this device has cost, and the microwave signal of output is stable.

Object of the present invention is achieved through the following technical solutions:

Based on the device that the microwave signal of Brillouin amplification multiple-wavelength laser produces, it is characterized in that comprising multiple-wavelength laser unit, first, second coupler unit, first, second filter cell and the first photodetector unit, the output of multiple-wavelength laser unit is connected with the input of the first coupler unit, two outputs of the first coupler unit are respectively with first, the input of the second filter cell connects, first, the output of the second filter cell is connected with two inputs of the second coupler unit respectively, the output of the second coupler unit is connected with the input of the first photodetector unit, the output of the first photodetector unit exports microwave signal,

Described multiple-wavelength laser unit comprise laser element, the 3rd, the 4th coupler unit, fiber amplifier, the first isolator, the first Polarization Controller, the first circulator, the first fiber unit and Brillouin laser unit, the output of laser element is connected with an input of the 3rd coupler, and two outputs of the 3rd coupler are connected with the input of the first isolator and the 4th coupler respectively; The output of the first isolator is connected with the input of the first Polarization Controller, the output of the first Polarization Controller is connected with the first port of the first circulator, second port of the first circulator is connected through the output of the first fiber unit with Brillouin laser unit, and the 3rd port of the first circulator is connected with another input of the 3rd coupler; The input of an output connecting fiber amplifier of the 4th coupler, another output is as the output of multiple-wavelength laser unit, and the output of fiber amplifier connects the input of Brillouin laser unit;

Described Brillouin laser unit is made up of the second circulator, the second Polarization Controller, the second fiber unit and the 5th coupler unit, the output of fiber amplifier is connected with the first port of the second circulator, second port of the second circulator is connected with an output of the 5th coupler unit through the second Polarization Controller, the second fiber unit, 3rd port of the second circulator is connected with the input of the 5th coupler unit, and another output of the 5th coupler unit connects the first fiber unit.

Said apparatus is utilized to produce the method for microwave signal, it is characterized in that: the laser that laser element produces is divided into two bundles through the 3rd coupler, wherein light beam enters into the first port of the first circulator after the first isolator and the first Polarization Controller, enter the first fiber unit from the second port of the first circulator, this light beam produces brillouin scattering signal dorsad in the first fiber unit, the another light beam exported from the 3rd coupler is divided into two-way after the 4th coupler, one road light is as the output light of multiple-wavelength laser unit, one road light enters amplifier unit, light after amplifier amplifies is as the pump light of Brillouin laser unit, the flashlight exported from fiber amplifier enters laser element through the first port of the second circulator, the second Polarization Controller is entered into from the second port of the second circulator, this flashlight enters in the second fiber unit according to clockwise direction, Brillouin scattering is dorsad produced in the second fiber unit, this dorsad brillouin scattering signal again according to counterclockwise direction second Polarization Controller, 3rd port of the second circulator enters the 5th coupler, with the second fiber unit circle transmission, Brillouin signal is exported from another output of the 5th coupler, this Brillouin laser signal enters into the first fiber unit and is exaggerated, flashlight after amplification enters the input of the 3rd coupler through the 3rd port of the first circulator, as the pump spectrum signal of multiple-wavelength laser after the flashlight exported with laser element is coupled, the output light of multiple-wavelength laser unit is divided into two bundles through the first coupler, filtering is carried out respectively through the first filter cell and the second filter cell, filtered two-beam is coupled on the second coupler unit, is converted to microwave signal exports by the first photodetector unit.

Stimulated Brillouin scattering (SBS) can be understood as light (pump light, the stokes light) interaction in a fiber that two bundles are propagated in opposite directions, can describe SBS process in theory by Maxwell equation and Wei Na mono-Stokes equations.If stokes light is propagated along+Z-direction, and Brillouin's pump light transmit along a Z-direction, ignore the cross direction profiles of light field and utilize and slowly change amplitude and be similar to, in SBS process, the three couple waves equation of pump light, stokes light and sound wave can be described as

$\left\{\begin{array}{c}-\frac{\∂E_p}{\∂z}+\frac{n_{\mathrm{fg}}}{c}\frac{\∂E_p}{\∂t}=-\frac{\mathrm{\α}}{2}{E}_p+{\mathrm{ig}}_2{E}_s\mathrm{\ρ}\\ \frac{\∂E_s}{\∂z}+\frac{n_{\mathrm{fg}}}{c}\frac{\∂E_s}{\∂t}=-\frac{\mathrm{\α}}{2}{E}_s+{\mathrm{ig}}_2{E}_p{\mathrm{\ρ}}^{*}\\ \frac{\∂\mathrm{\ρ}}{\∂t}+(\frac{{\mathrm{\Γ}}_B}{2}-\mathrm{i\Δ\ω})\mathrm{\ρ}=i\frac{g_1}{\mathrm{\η}}{E}_p{E}_s^{*}\end{array}\right.---\left(1\right)$

Wherein, E _p, E _swith the complex amplitude that ρ is pump light, stokes light and sound wave respectively, n _fgbe the group index of optical fiber, α is the loss factor of optical fiber, γ=Γ _b/ 2 π are brillouin gain spectrum bandwidth, Δ ω=ω _p0-ω _s0-Ω _bdepart from brillouin gain spectrum center (ω _s0) mismatching angle, Ω _bthat the angular frequency of Brillouin scattering moves, ω _p0, ω _s0the centre frequency of pump light and stokes light, g ₂=γ _eω _p0/ (4cn _fρ ₀), η=cn _fε ₀/ 2, γ _ethe electrostriction coefficient in optical fiber, ε ₀the conductivity in vacuum, n _ffor the phase refractive index of optical fiber, ρ ₀the density of material, V _afor sound wave propagation velocity, ignore the loss of pump light, for weak Stokes light field, equation (1) can be reduced to:

$\left\{\begin{array}{c}\frac{\∂E_s}{\∂z}+\frac{n_{\mathrm{fg}}}{c}\frac{\∂E_s}{\∂t}={\mathrm{ig}}_2{E}_p{\mathrm{\ρ}}^{*}\\ \frac{{\∂\mathrm{\ρ}}^{*}}{\∂t}+(\frac{{\mathrm{\Γ}}_B}{2}+\mathrm{i\Δ\ω}){\mathrm{\ρ}}^{*}=-i\frac{g_1}{\mathrm{\η}}{E}_s{E}_p^{*}\end{array}\right.---\left(2\right)$

Through Fourier transform, equation (2) is transformed on frequency domain, can draw:

$\left\{\begin{array}{c}\frac{\∂{\tilde{E}}_s}{\∂z}-i(\mathrm{\ω}-{\mathrm{\ω}}_{s0})\frac{n_{\mathrm{fg}}}{c}{\tilde{E}}_s={\mathrm{ig}}_2{E}_p{\widetilde{\mathrm{\ρ}}}^{*}\\ [\frac{{\mathrm{\Γ}}_B}{2}-i({\mathrm{\ω}-\mathrm{\ω}}_{p0}+{\mathrm{\Ω}}_B)]{\widetilde{\mathrm{\ρ}}}^{*}=-i\frac{g_1}{\mathrm{\η}}{\tilde{E}}_s{E}_p^{*}\end{array}\right.---\left(3\right)$

Wherein with e respectively _sand ρ ^*fourier transform, to be disappeared ρ by equation (3) ^*, namely obtain frequency domain Stokes light equation:

$\left\{\begin{array}{c}\frac{\∂{\tilde{E}}_s}{\∂z}=i(\mathrm{\ω}-{\mathrm{\ω}}_{s0})\frac{n_{\mathrm{fg}}}{c}{\tilde{E}}_s+\frac{\frac{{2g}_1{g}_1}{{\mathrm{\η\Γ}}_B}{\left|E_p\right|}^2}{1-i2\mathrm{\δ\ω}/{\mathrm{\Γ}}_B}{\tilde{E}}_s\\ \frac{\∂{\tilde{E}}_s}{\∂z}=[i(\mathrm{\ω}-{\mathrm{\ω}}_{s0})\frac{n_{\mathrm{fg}}}{c}+\frac{g_0{I}_p/2}{1-i2\mathrm{\δ\ω}/{\mathrm{\Γ}}_B}]{\tilde{E}}_s\end{array}\right.---\left(4\right)$

Wherein, g ₀=4g ₁g ₂/ (η Γ _b) be gain factor, δ ω=ω-ω _p0+ Ω _b, I _pit is pump light intensities.On frequency domain, consider the stokes light of edge+Z-direction transmission, then have:

$\frac{\∂{\tilde{E}}_s}{\∂z}=i[k_s\left(\mathrm{\ω}\right)-k_s\left({\mathrm{\ω}}_{s0}\right)]{\tilde{E}}_s---\left(5\right)$

Can be drawn by equation (4) and (5):

$k_s\left(\mathrm{\ω}\right)-k_s\left({\mathrm{\ω}}_{s0}\right)=\mathrm{\ω}\frac{n_{\mathrm{fg}}}{c}-i\frac{g_0{I}_p/2}{1-i2\mathrm{\δ\ω}{/\mathrm{\Γ}}_B}-{\mathrm{\ω}}_{s0}\frac{n_{\mathrm{fg}}}{c}---\left(6\right)$

Can be drawn by equation (6):

$k_s\left(\mathrm{\ω}\right)=\mathrm{\ω}\frac{n_f}{c}-i\frac{g_0{I}_p/2}{1-i2\mathrm{\δ\ω}{/\mathrm{\Γ}}_B}\≡\widetilde{n_s}\frac{\mathrm{\ω}}{c}---\left(7\right)$

According to equation (7), effective complex refractivity index of stokes wave can be expressed as:

$\widetilde{n_s}=n_{\mathrm{fg}}-i\frac{c}{2\mathrm{\ω}}\frac{g_0{I}_p}{1-i2\mathrm{\δ\ω}{/\mathrm{\Γ}}_B}---\left(8\right)$

Single color plane ripple propagation velocity is in a fiber phase velocity, and when wave envelope is propagated in a fiber, each plane phase velocity of wave of composition envelope is different, and the propagation velocity at definition wave envelope center is group velocity.Can find out that stokes wave experienced by gain and the dispersion of Lorentz shape resonance spectrum from equation (8), the real part of complex refractivity index is the refractive index of stokes wave the imaginary part of complex refractivity index is relevant with the gain coefficient of Stokes, group index n _g=n _s+ ω (dn _s/ d ω), the gain of stokes wave can be expressed as:

$g_s\left(\mathrm{\ω}\right)=\frac{g_0{I}_p}{1+4{({\mathrm{\ω}-\mathrm{\ω}}_{p0}+{\mathrm{\Ω}}_B)}^2/{\mathrm{\Γ}}_B^2}---\left(9\right)$

As can be seen from equation (9), when the frequency of flashlight equals the frequency of pump light, the gain of flashlight reaches maximum.Therefore, in our invention system, fiber unit 108 and 110 is identical optical fiber, namely Brillouin shift is identical, or adopt the optical fiber that Brillouin shift is close, so just can ensure that flashlight is identical with the frequency of pump light or at utmost close, make the gain characteristic that flashlight reaches maximum.Again by the circulation pumping of coupler 102, so just multiple-wavelength laser can be obtained.In order to control the quality of microwave signal, add the first isolator 113 and two Polarization Controllers 107,112.

Described Brillouin laser unit 105 is single-frequency Brillouin laser, also can be the Brillouin laser unit of other structure.

Described two fiber units 108,110 can be the different fiber that identical optical fiber or Brillouin shift are close, can be monomode fibers, also can be other kind of type optical fibers.

Described first photodetector unit 118 can be balanced detector, also can be the photodetector of other kind.

The tunability of described microwave signal, can obtain by regulating the pumping wavelength of laser 101, or obtained by the brillouin frequency in-migration of change first fiber unit 110 and the second fiber unit 108, can also be obtained by the centre wavelength changing filter unit median filter unit 115 and 116.

The invention has the beneficial effects as follows: the method and apparatus that a kind of microwave signal based on Brillouin amplification multiple-wavelength laser that the present invention proposes produces, by controlling the power of pump light, the tunable high-frequency microwave signal in many broadbands can be obtained; The present invention is by designing simple multiple-wavelength laser, and by controlling the Brillouin shift of its gain fibre, or obtain tunable microwave signal source by the centre wavelength of adjustment two filters, can also by the frequency regulating the wavelength etc. of laser to carry out regulation output microwave signal.The apparatus and method of the microwave signal that the present invention designs can not only produce high-frequency microwave signal, and can obtain multi-band wide tunable microwave signal; Apparatus of the present invention do not need electronic device, greatly reduce electromagnetic interference etc., and have with low cost, the simple advantage of structure.

Accompanying drawing explanation

Fig. 1 is the structural representation of the embodiment of the present invention one.

Fig. 2 is the structural representation of the embodiment of the present invention two.

Fig. 3 is the spectrum of the multiple-wavelength laser that the embodiment of the present invention obtains.

Fig. 4 is the 10.8GHz microwave signal frequency spectrum that the embodiment of the present invention obtains.

Fig. 5 is the 21.6GHz microwave signal frequency spectrum that the embodiment of the present invention obtains.

Fig. 6 is the 32.4GHz microwave signal frequency spectrum that the embodiment of the present invention obtains.

Embodiment

Below in conjunction with drawings and Examples the present invention be described in further detail and describe.

Embodiment one:

The present embodiment provides a kind of high-frequency tunable microwave signal generation device based on Brillouin amplification multiple-wavelength laser, all can conveniently be built by the fiber plant of existing laser and Brillouin principle.As shown in Figure 1, the present embodiment comprises laser element 101, this laser is tunable laser (Agilent lightwave measurement system8164B), arranging output wavelength is 1550nm, power is 0dBm, its light exported is divided into two bundles by the 3rd coupler unit 102 (50:50) of 3dB, wherein the light of a port of 50% enters into the first isolator 113, the signal exported from the first isolator 113 to enter into the first port of the first circulator 111 through the first Polarization Controller 112, the first fiber unit 110 is entered from the second port of the first circulator 111, first fiber unit 110 is the monomode fiber of 20km, light signal produces brillouin scattering signal dorsad in the first fiber unit 110, another road signal exported from the 3rd coupler unit 102 enters erbium-doped fiber amplifier 104 (KPS-BT2-C-30-PB-FA) through a port of the 4th coupler unit 103 (80:20) 20%, peak power output 30dBm, the signal exported from erbium-doped fiber amplifier 104 is as the pumping source of Brillouin laser unit 105.Brillouin laser unit 105 comprises the second circulator 106, second Polarization Controller 107, second fiber unit 108 (general single mode fiber of 6m) and the 5th coupler 109 (70:30), the flashlight exported from fiber amplifier 104 enters laser element 105 through the first port of the second circulator 106, the second Polarization Controller 107 is entered into from the second port of the second circulator 106, this flashlight enters in the second fiber unit 108 according to clockwise direction, Brillouin scattering is dorsad produced in the second fiber unit 108, this dorsad brillouin scattering signal again according to counterclockwise direction second Polarization Controller 107, 3rd port of the second circulator 106 enters the 5th coupler 109, by the 5th coupler 109 70% output port and the second fiber unit 108 circle transmission, from the output port output Brillouin signal of 30% of the 5th coupler 109, this Brillouin signal enters the first fiber unit 110.80% multiwavelength laser exported from the 4th coupler 103 is divided into two bundles through first coupler unit 114 of 3dB, one road signal is through the first filter (FBG filter) 115 filtering, another road signal is through the second filter (tunable filter) 116 (Santec OTF-300) filtering, two paths of signals enters into the first photodetector unit 118 after being coupled on second coupler unit 117 of 3dB, and this detector cells is u ²t high speed photodetector, bandwidth is 50GHz, be converted to microwave signal by the first photodetector unit 118 to export, output signal carries out Measurement and analysis through Agilent spectrum analyzer (Agilent E4440A), and light signal is analyzed by spectroanalysis instrument (Agilent86140B Optical Spectrum Ananlyzer).Pass through emulation experiment, obtain spectrum, 10.8GHz microwave signal, 21.6GHz microwave signal, the 32.4GHz microwave signal of the multiple-wavelength laser as shown in Fig. 3,4,5,6, the tuning centre wavelength by adjustment filter of the present embodiment microwave signal realizes.The tuning of microwave signal by regulating the pumping wavelength of laser 101, or can also be realized by the brillouin frequency in-migration of change two fiber units 110,108.As can be seen from the spectrum of Fig. 3 multiple-wavelength laser, obtain 11 grades of multi-wavelength Brillouin scattered signals, utilize the multi-wavelength Brillouin signal obtained to carry out difference frequency and obtain tunable high-frequency signal, the frequency signal obtained is respectively 10.8,21.6 and 32.4GHz, can find out that the present invention effectively can obtain the microwave signal of high-frequency tunable from the result of experiment.

Embodiment two: as shown in Figure 2, compared with the microwave signal generation device structure of embodiment one, the structure of multi-wavelength Brillouin laser unit 100 is identical, difference is: the output signal of multi-wavelength Brillouin laser unit 100 enters into fiber grating unit 119, the output of fiber grating unit 119 connects the second isolator 120, the output of the second isolator 120 connects the 3rd filter unit (tunable filter unit) 121, the output of the 3rd filter unit 121 is connected to the second photodetector unit 122, be converted to microwave signal by the second photodetector unit 122 to export..The 3rd filter unit 121 in embodiment two can adopt the tunable filter unit same with the second filter unit 116 in embodiment one, and the second photodetector unit 122 can adopt the photodetector same with the first photodetector unit 118 in embodiment one.

Although the present invention is described by specific embodiment, specific embodiments and the drawings are not used for limiting the present invention.Those skilled in the art in the scope of spirit of the present invention, can make various distortion and improvement, and these distortion and improvement do not exceed the scope of protection of present invention.

Claims (10)

1. based on the device that the microwave signal of Brillouin amplification multiple-wavelength laser produces, it is characterized in that comprising multiple-wavelength laser unit (100), first, second coupler unit (114,117), first, second filter cell (115,116) and the first photodetector unit (118)

The output of multiple-wavelength laser unit (100) is connected with the input of the first coupler unit (114), two outputs of the first coupler unit (114) are respectively with first, second filter cell (115, 116) input connects, first, second filter cell (115, 116) output is connected with two inputs of the second coupler unit (117) respectively, the output of the second coupler unit (117) is connected with the input of the first photodetector unit (118), the output of the first photodetector unit (118) exports microwave signal,

Described multiple-wavelength laser unit (100) comprises laser element (101), 3rd, 4th coupler unit (102, 103), fiber amplifier (104), first isolator (113), first Polarization Controller (112), first circulator (111), first fiber unit (110) and Brillouin laser unit (105), the output of laser element (101) is connected with an input of the 3rd coupler (102), two outputs of the 3rd coupler (102) are connected with the input of the first isolator (113) and the 4th coupler (103) respectively, the output of the first isolator (113) is connected with the input of the first Polarization Controller (112), the output of the first Polarization Controller (112) is connected with the first port of the first circulator (111), second port of the first circulator (111) is connected through the output of the first fiber unit (110) with Brillouin laser unit (105), and the 3rd port of the first circulator (111) is connected with another input of the 3rd coupler (102), the input of an output connecting fiber amplifier (104) of the 4th coupler (103), another output is as the output of multiple-wavelength laser unit (100), and the output of fiber amplifier (104) connects the input of Brillouin laser unit (105),

Described Brillouin laser unit (105) is by the second circulator (106), second Polarization Controller (107), second fiber unit (108) and the 5th coupler unit (109) are formed, the output of fiber amplifier (104) is connected with the first port of the second circulator (106), second port of the second circulator (106) is through the second Polarization Controller (107), second fiber unit (108) is connected with an output of the 5th coupler unit (109), 3rd port of the second circulator (106) is connected with the input of the 5th coupler unit (109), another output of 5th coupler unit (109) connects the first fiber unit (110).

2. according to the device that the microwave signal based on Brillouin amplification multiple-wavelength laser described in claim 1 produces, it is characterized in that: described first, second fiber unit (110,108) is identical fiber unit, or the fiber unit that Brillouin shift is close.

3. the device of the generation of the microwave signal based on Brillouin amplification multiple-wavelength laser according to claim 1, is characterized in that: described Brillouin laser unit (105) is single-frequency Brillouin laser.

4. the device of the generation of the microwave signal based on Brillouin amplification multiple-wavelength laser according to claim 1, is characterized in that: described first photodetector unit (118) is balanced detector.

5. the device of the generation of the microwave signal based on Brillouin amplification multiple-wavelength laser according to claim 1, it is characterized in that: be connected with multiple-wavelength laser unit (100) first, second coupler unit (114, 117), first, second filter cell (115, 116) and the first photodetector unit (118) replaces with fiber grating unit (119), second isolator (120), 3rd filter unit (121) and the second photodetector unit (122), multiple-wavelength laser unit (100) and fiber grating unit (119), second isolator (120), 3rd filter unit (121) is connected in turn with the second photodetector unit (122), the output of the second photodetector unit (122) exports microwave signal.

6. utilize the device described in claim 1 to produce the method for microwave signal, it is characterized in that: the laser that laser element (101) produces is divided into two bundles through the 3rd coupler (102), wherein light beam enters into the first port of the first circulator (111) after the first isolator (113) and the first Polarization Controller (112), enter the first fiber unit (110) from the second port of the first circulator (111), this light beam produces brillouin scattering signal dorsad in the first fiber unit (110), the another light beam exported from the 3rd coupler (102) is divided into two-way after the 4th coupler (103), one road light is as the output light of multiple-wavelength laser unit (100), one road light enters amplifier unit (104), light after amplifier (104) amplifies is as the pump light of Brillouin laser unit (105), the flashlight exported from fiber amplifier (104) enters laser element (105) through the first port of the second circulator (106), the second Polarization Controller (107) is entered into from the second port of the second circulator (106), this flashlight enters in the second fiber unit (108) according to clockwise direction, Brillouin scattering is dorsad produced in the second fiber unit (108), this dorsad brillouin scattering signal again according to counterclockwise direction second Polarization Controller (107), 3rd port of the second circulator (106) enters the 5th coupler (109), with the second fiber unit (108) circle transmission, Brillouin signal is exported from another output of the 5th coupler (109), this Brillouin laser signal enters into the first fiber unit (110) and is exaggerated, flashlight after amplification enters the input of the 3rd coupler (102) through the 3rd port of the first circulator (111), as the pump spectrum signal of multiple-wavelength laser (100) after the flashlight exported with laser element (101) is coupled, the output light of multiple-wavelength laser unit (100) is divided into two bundles through the first coupler (114), filtering is carried out respectively through the first filter cell (115) and the second filter cell (116), filtered two-beam, in the upper coupling of the second coupler unit (117), is converted to microwave signal by the first photodetector unit (118) and exports.

7. the method for generation microwave signal according to claim 6, is characterized in that by regulating the pumping wavelength of laser element (101) to obtain tunable microwave signal.

8. the method for generation microwave signal according to claim 6, is characterized in that the brillouin frequency in-migration by changing the first fiber unit (110) and the second fiber unit (108) obtains tunable microwave signal; The Brillouin shift changing gain fibre is realized by temperature controller or Stress Control device.

9. the method for generation microwave signal generation according to claim 6, is characterized in that the centre wavelength by changing first, second filter cell (115,116) obtains tunable microwave signal.

10. the method for generation microwave signal according to claim 6, is characterized in that the Brillouin laser signal that control Brillouin laser unit (105) exports is identical with the wavelength entering the brillouin scattering signal dorsad produced in fiber unit 110 through the first circulator (111) second ports, direction is identical.