CN101794964A - Photoproduction microwave device based on double-wavelength Brillouin optical fiber laser - Google Patents

Abstract

An optically-generated microwave device based on a dual-wavelength Brillouin fiber laser in the field of photoelectric technology, including: a DFB single-frequency laser, a fiber amplifier, a fiber circulator, an optical resonant cavity, a cascaded resonant cavity, a photodetector and a spectrum analyzer. The cascaded resonant cavities and the optical resonant cavities respectively generate single-mode lasers with different frequencies. The present invention does not need to use an additional microwave signal source for optical frequency stabilization or optical modulation, and is an all-fiber optical path structure, which has the advantages of simple structure and low cost, and the Brillouin lasers generated by the two resonators are all produced by the same Generated by DFB single-frequency laser pumping, the microwave signal generated by the beat frequency of this dual-wavelength Brillouin fiber laser has high frequency stability.

Description

Optically generated microwave device based on dual-wavelength Brillouin fiber laser

technical field

The invention relates to a device in the field of optoelectronic technology, in particular to an optically generated microwave device based on a dual-wavelength Brillouin fiber laser.

Background technique

The traditional method of generating high-frequency microwave signals is mainly to realize the step-by-step frequency multiplication of low-frequency microwave signals through complex electronic circuits - electro-generated microwave technology. Although this method is relatively mature in technology, the electronic circuit system used for high-frequency microwave signal generation is relatively complicated and expensive. Moreover, in many applications, the generated microwave signal needs to be transmitted over a long distance, and if it is transmitted through ordinary coaxial cables or air, the loss is very large (the transmission loss of 60GHz microwave in the atmosphere is 14dB/km). Therefore, electro-generated microwave technology has encountered bottlenecks that are increasingly difficult to overcome. In recent years, a new high-frequency microwave generation technology has been developed—optical microwave technology can overcome the current bottleneck encountered in the field of electric microwave technology. Due to the extremely high frequency of the optical signal, the frequency of the microwave signal generated by the beat frequency can easily reach GHz, or even tens of GHz. Optical signals are transmitted through optical fibers, and optical fibers have the characteristics of broadband, low loss, and low cost. Therefore, optically generated microwave signals can be transmitted over long distances, and the cost and complexity of the system are greatly reduced.

In the prior art, there are three ways to achieve optically generated microwaves: the first is to generate laser light by two independent single-frequency lasers to perform beating frequency, and the frequency of the beating frequency microwave signal is the difference between the output laser frequencies of the two lasers. However, in order to obtain microwave signals with low phase noise and high frequency stability, the phases of the two laser sources must be locked, which requires the use of optical injection locking technology or optical phase locked ring technology, and these two optical locking technologies require A high-stable microwave reference signal source; the second optical-generated microwave technology uses external modulation techniques, but this technology also requires a high-stable microwave reference signal source, which also increases the cost and complexity of the system; the third optical-generated microwave The technology uses a laser, which is a single longitudinal mode and dual-wavelength output. The optically generated microwave signal can be obtained by directly beating the dual-wavelength laser output. This technology has the characteristics of high frequency stability and low phase noise, and does not require Use a highly stable reference microwave signal source.

After searching the existing literature, it was found that Jianping Yao (Yao Jianping) from the University of Ottawa in Canada et al. wrote in IEEE Transactions on microwave theory and techniques, 2006, 54(2), 804-809 (2006 "Microwave Theory and Technology", Volume 54, No. 804-809 of Issue 2) published an article entitled "Photonic generation of microwavesignal using a dual-wavelength single-longitudinal-mode fiber ring laser (photonic generation of microwave signal using a dual-wavelength single-longitudinal-mode fiber ring laser)", This technology uses two specially made FBGs (Fiber Bragg Gratings) for laser mode selection. One FBG uses its transmission line, and the other FBG uses its reflection line. When the lines of the two FBGs overlap properly , this fiber ring laser can obtain single longitudinal mode and dual wavelength output, and the microwave signal can be obtained by directly beating the laser output. However, this technology has very strict requirements on the characteristics of the two FBGs, which increases the difficulty of making this FBG and also makes the system cost higher.

Contents of the invention

The object of the present invention is to overcome the above-mentioned deficiencies of the prior art, and provide an optically generated microwave device based on a dual-wavelength Brillouin fiber laser. The present invention achieves the generation of microwave signals with high frequency stability by beating the dual-wavelength output of the laser, without using an additional reference microwave signal source for optical frequency stabilization or optical modulation, and is an all-fiber optical path structure with The advantages of simple structure and low cost.

The present invention is achieved through the following technical solutions, the present invention includes: DFB (distributed feedback semiconductor) single-frequency laser, optical fiber amplifier, optical fiber circulator, optical resonant cavity, cascaded resonant cavity, photodetector and spectrum analyzer, wherein: DFB The single-frequency laser is connected to the fiber amplifier to transmit the single-frequency laser signal, the fiber amplifier is connected to the first port of the fiber circulator to transmit the amplified single-frequency laser signal, and the second port of the fiber circulator is connected to the optical resonator to transmit the amplified The single-frequency laser signal, the optical resonator is connected to the cascade resonator to transmit the amplified single-frequency laser signal, the third port of the fiber circulator is connected to the photodetector to transmit the dual-wavelength laser signal, and the photodetector is connected to the spectrum analyzer Transmission of beat frequency microwave signals.

The cascaded resonant cavity and the optical resonant cavity respectively generate single-mode lasers with different frequencies.

The optical fiber amplifier is used to amplify the single-frequency laser signal output by the DFB single-frequency laser, including: the first pump source, the second pump source, the first WDM (wavelength division multiplexer), the second WDM and doping Optical fiber, wherein: the first pumping source is connected to one split-wave end of the first WDM to transmit pump light, the DFB single-frequency laser is connected to the other split-wave end of the first WDM to transmit a single-frequency laser signal, and the combination of the first WDM The wave end is connected to one end of the doped fiber to transmit the laser signal, the other end of the doped fiber is connected to the multiplex end of the second WDM to transmit the laser signal, and one end of the second WDM is connected to the second pump source to transmit the pump The other demultiplexing end of the second WDM is connected to the first port of the fiber circulator to transmit the amplified single-frequency laser signal.

The doped fiber is one of erbium-doped fiber, ytterbium-doped fiber and thulium-doped fiber.

The optical resonant cavity is used to generate the first wavelength laser, including: a first four-port coupler, a first isolator and a first optical fiber, wherein: the first input end of the first four-port coupler and the fiber circulator The second port is connected, the second input end of the first four-port coupler is connected with the input end of the first isolator, the output end of the first isolator is connected with one end of the first optical fiber, and the other end of the first optical fiber is connected with the first end of the first optical fiber. The first output end of the first four-port coupler is connected, and the second output end of the first four-port coupler is connected with the cascade resonant cavity.

The first optical fiber is one of DCF (dispersion compensation fiber), DSF (dispersion-shifted fiber), NZDSF (non-zero dispersion-shifted fiber), SMF (single-mode fiber) and HNLF (high nonlinear fiber).

The cascaded resonant cavity is used to generate the second wavelength laser, including: a second four-port coupler, a second isolator and a second optical fiber, wherein: the first input end of the second four-port coupler is connected to the first four-port coupler The second output end of the port coupler is connected, the second input end of the second four-port coupler is connected with the input end of the second isolator, the output end of the second isolator is connected with one end of the second optical fiber, and the second optical fiber The other end of is connected to the first output end of the second four-port coupler, and the second output end of the second four-port coupler is vacant.

The second optical fiber is one of DCF, DSF, NZDSF, SMF and HNLF.

The working principle of the present invention is: DFB single-frequency laser is used as a signal source, and the single-frequency laser signal output by it is amplified by a fiber amplifier and then passed through a fiber circulator, and then input as Brillouin pump light into an optical resonator and a cascade resonator respectively. The two resonators are respectively embedded with different types of optical fibers as the Brillouin gain medium, then the frequency of the first-order Brillouin laser excited in the resonator is

f＝f ₀ +v _B (1)

Among them: f ₀ is the frequency of Brillouin pumping light, that is, the output frequency of DFB single-frequency laser, and v _B is the Brillouin frequency shift corresponding to the embedded fiber when the wavelength of Brillouin pumping light is λ _P , which is :

v _B ＝2nυ _A /λ _P (2)

Where: n is the refractive index at the pump wavelength λ _P. υ _A is the speed of sound in the fiber, it is only related to the properties of the fiber itself, and has

${\mathrm{<span\; class="notranslate">\; \&upsi;</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; =</span>\sqrt{\mathrm{<span\; class="notranslate">\; \&gamma;</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; \&rho;</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

Among them: γ is the Young's modulus of the fiber material, and ρ is the bulk density of the fiber material.

If different kinds of optical fibers are embedded in different resonators, the two resonators will excite two kinds of Brillouin lasers with different frequencies, and the Brillouin frequency shifts are v _B1 and v _B2 respectively. Because in the optical fiber, the stimulated Brillouin light only occurs in the backward direction relative to the running direction of the Brillouin pump light (defined as the forward direction), so the Brillouin light of two different frequencies produced by the two resonators The laser light will be output from the third port of the fiber optic circulator, and when it is connected to the photodetector, the beat frequency microwave signals of the two Brillouin lasers can be obtained, and the frequency of the obtained beat frequency microwave signals is

f _RF ＝|v _B1 -v _B2 | (4)

Compared with the prior art, the beneficial effect of the present invention is that it does not need to use an additional microwave signal source for optical frequency stabilization or optical modulation, and it is an all-fiber optical path structure, which has the advantages of simple structure and low cost, and two resonant The Brillouin laser generated by the cavity is all pumped by the same DFB single-frequency laser, so the microwave signal generated by the beat frequency of this dual-wavelength Brillouin fiber laser has high frequency stability.

Description of drawings

Fig. 1 is a structural representation of the present invention;

Among them: 1-DFB single-frequency laser; 2-first pump source; 3-first WDM; 4-doped fiber; 5-second WDM; 6-second pump source; 7-fiber circulator; 8 -first four-port coupler; 9-first optical fiber; 10-first isolator; 11-second four-port coupler; 12-second optical fiber; 13-second isolator; 14-photodetector; 15 -Spectrum Analyzer.

Fig. 2 is the structural representation of four-port coupler;

Among them: 16-the first input port; 17-the second input port; 18-the second output port; 19-the first output port.

Fig. 3 is the beat frequency microwave signal spectrogram that embodiment obtains;

Wherein: (a) is the beat frequency microwave signal spectrum diagram that embodiment 1 obtains; (b) is the beat frequency microwave signal spectrum diagram that embodiment 2 obtains; (c) is the beat frequency microwave signal spectrum diagram that embodiment 3 obtains; (d) is the beat frequency microwave signal spectrum diagram that embodiment 4 obtains; (e) is the beat frequency microwave signal spectrum diagram that embodiment 5 obtains; (f) is the beat frequency microwave signal spectrum diagram that embodiment 6 obtains.

Fig. 4 is a schematic diagram showing the variation of the frequency of the beat frequency microwave signal obtained in Example 2 with the output frequency of the DFB laser.

FIG. 5 is a schematic diagram showing the variation of the frequency of the beat-frequency microwave signal obtained in Example 2 with the measurement time.

Detailed ways

The embodiments of the present invention are described in detail below in conjunction with the accompanying drawings: this embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating procedures are provided, but the protection scope of the present invention is not limited to the following the described embodiment.

Example 1

As shown in Figure 1, the present embodiment includes: DFB single-frequency laser 1, erbium-doped fiber amplifier, fiber circulator 7, optical resonator, cascade resonator, photodetector 14 and spectrum analyzer 15, wherein: DFB single-frequency The laser 1 is connected to the input end of the erbium-doped fiber amplifier to amplify the single-frequency laser signal output by the DFB single-frequency laser 1. The output end of the erbium-doped fiber amplifier is connected to the first port of the fiber circulator 7, and its second port is connected to the optical resonance The optical resonator is connected to the cascade resonator, the amplified single-frequency laser is sequentially input into the optical resonator and the cascade resonator through the second port of the circulator 7, and the third port of the fiber circulator outputs a dual-wavelength Bri The third port of the laser signal of the deep fiber laser is connected to the photodetector 14 to beat the laser signal, and the photodetector 14 is connected to the spectrum analyzer 15 to measure the microwave signal obtained by the beat frequency.

The erbium-doped fiber amplifier is used to amplify the single-frequency laser signal output by the DFB single-frequency laser 1 as Brillouin pumping light, including: the first 980nm pumping source 2, the second 980nm pumping source 6, the first WDM3, the second WDM 5, and EDF (erbium-doped fiber) 4, wherein: one branch port of the first WDM 3 is connected to the DFB single-frequency laser 1, and the first 980nm pump source 2 is connected to the other branch port of the first WDM 3 The wave port of the first WDM 3 is connected to one end of the EDF 4, the other end of the EDF 4 is connected to the wave port of the second WDM 5, and the wave port of the second WDM 5 is connected to the second 980 pump source 6 Connect, another demultiplexing port of the second WDM 5 is connected with the 1 port of the optical fiber circulator 7 as the output port of the erbium-doped fiber amplifier.

Described optical resonant cavity is used for producing first wavelength laser, comprises: first four-port coupler 8, first isolator 10 and DCF 9, wherein: described first four-port coupler 8 is that coupling ratio is 50/ The four-port coupler of 50, its first input port is connected with the second port of fiber optic circulator 7, and the second input port is connected with the input end of the first isolator 10, and the output end of the first isolator 10 is connected with DCF 9 one end The other end of the DCF 9 is connected to the first output port of the first four-port coupler 8, and the second output port of the first four-port coupler 8 is used as the extraction port of another part of the Brillouin pump light and the second four-port The first input port of the coupler 11 is connected.

Described cascaded resonator is used to produce the second wavelength laser, comprises: the second four-port coupler 11, the second isolator 13 and DSF 12, wherein: the second four-port coupler 11 is that the coupling ratio is 50/50 Four-port coupler, its first input port is connected with the second output port of the first four-port coupler 8, and the second input port of the second four-port coupler 11 is connected with the second isolator 13 input , the output end of the second isolator 13 is connected to one end of the DSF 12, the other end of the DSF 12 is connected to the first output port of the second four-port coupler 11, and the second output port of the second four-port coupler 11 is vacant.

A schematic structural diagram of the four-port coupler is shown in FIG. 2 .

The wavelength of the DFB single-frequency laser 1 described in this embodiment is 1544nm.

The maximum output power of the first 980nm pump source 2 is 330mW, and the maximum output power of the second 980nm pump source 6 is 250mW, and the power of the two 980nm pump sources can be continuously adjusted.

The length of the erbium-doped optical fiber 4 is 13.5m, and the doping concentration is 400ppm.

The length of said DCF 9 is 200m, and its Brillouin frequency shift is 9.77GHz.

The length of the DSF 12 is 500m, and its Brillouin frequency shift is 10.718GHz.

During the work of the present embodiment, the output signal optical power of the DFB single-frequency laser 1 is adjusted to the maximum (10mW), the output power of the two 980nm pump sources is adjusted to the maximum, and the power of the signal light rises to 206mW, and then pass through the specific wavelength (1550nm) fiber circulator 7 to filter out the redundant 980nm pump light and then input the two resonators as the Brillouin pump light, the optical resonator and the cascade resonator respectively excite the Brillouin pump light of different wavelengths The deep laser is finally output to the photodetector 14 through the third port of the optical fiber circulator 7 for beating frequency. The frequency of the beating frequency microwave signal is 948.0MHz, and the spectrum diagram of the obtained microwave signal is shown in Fig. 3(a).

Example 2

The difference between this embodiment and Embodiment 1 is that: in this embodiment, the second optical fiber in the cascaded resonator is HNLF, the length of the HNLF is 253 m, and the corresponding Brillouin frequency shift is HNLF: 9.405 GHz.

The measurement resolution of the spectrum analyzer 15 is 0.1 MHz.

The frequency of the beat-frequency microwave signal obtained in this embodiment is 365.6 MHz, and its frequency spectrum is shown in FIG. 3( b ).

The schematic diagram of the frequency change of the beat-frequency microwave signal obtained in this embodiment is shown in Figure 4. From Figure 4, it can be seen that the frequency of the beat-frequency microwave signal varies with the frequency of the pump light by a very small amount, which is smaller than the measurement resolution of the spectrum analyzer. 0.1MHz.

After two hours of measurement, the schematic diagram of the frequency of the beat frequency microwave signal obtained in this embodiment varies with the measurement time, as shown in Figure 5. As can be seen from Figure 5, the frequency of the beat frequency microwave signal is very little affected by the surrounding environment parameters (temperature, humidity) , less than the measurement resolution of the spectrum analyzer 0.1MHz.

From Fig. 4 and Fig. 5, it can be seen that the microwave signal obtained in this embodiment has high frequency stability.

Example 3

The difference between this embodiment and Embodiment 1 is that the second optical fiber in the cascaded resonator in this embodiment is NZDSF, the length of the NZDSF is 350 m, and the corresponding Brillouin frequency shift is 10.895 GHz.

The frequency of the beat-frequency microwave signal obtained in this embodiment is 1115.0 MHz, and its frequency spectrum is shown in FIG. 3( c ).

Example 4

The difference between this embodiment and Embodiment 3 is that: in this embodiment, the first optical fiber in the optical resonant cavity is a DSF, the length of the DSF is 200 m, and the corresponding Brillouin frequency shift is 10.718 GHz.

The frequency of the beat-frequency microwave signal obtained in this embodiment is 175.0 MHz, and its frequency spectrum is shown in FIG. 3( d ).

Example 5

As shown in Figure 1, this embodiment includes: DFB single-frequency laser 1, ytterbium-doped fiber amplifier, fiber circulator 7, optical resonant cavity, cascaded resonant cavity, photodetector 14 and spectrum analyzer 15, wherein: DFB single-frequency The laser 1 is connected to the input end of the ytterbium-doped fiber amplifier to amplify the single-frequency laser signal output by the DFB single-frequency laser 1. The output end of the ytterbium-doped fiber amplifier is connected to the first port of the fiber circulator 7, and its second port is connected to the optical resonance The optical resonator is connected to the cascade resonator, the amplified single-frequency laser is sequentially input into the optical resonator and the cascade resonator through the second port of the circulator 7, and the third port of the fiber circulator outputs a dual-wavelength Bri For the laser signal of the deep fiber laser, its 3 ports are connected to the photodetector 14 to beat the laser signal, and the photodetector 14 is connected to the spectrum analyzer 15 to measure the microwave signal obtained by the beat frequency.

The ytterbium-doped fiber amplifier is used to amplify the single-frequency laser signal output by the DFB single-frequency laser 1 as Brillouin pumping light, including: the first 980nm pumping source 2, the second 980nm pumping source 6, the first WDM 3, the second WDM 5 and YbDF 4, wherein: one demultiplexing port of the first WDM 3 is connected to the DFB single-frequency laser 1, and the first 980nm pump source 2 is connected to another demultiplexing port of the first WDM 3, The multiplex port of the first WDM 3 is connected to one end of the YbDF 4, the other end of the YbDF 4 is connected to the multiplex port of the second WDM 5, the one-demultiplex port of the second WDM 5 is connected to the second 980 pump source 6, and the second Another demultiplexing port of the WDM 5 is connected with the 1 port of the optical fiber circulator 7 as the output port of the ytterbium-doped fiber amplifier.

Described optical resonant cavity is used for producing first wavelength laser, comprises: first four-port coupler 8, first isolator 10 and SMF 9, wherein: described first four-port coupler 8 is that coupling ratio is 50/ The four-port coupler of 50, its first input port is connected with the second port of fiber optic circulator 7, and the second input port is connected with the input end of the first isolator 10, and the output end of the first isolator 10 is connected with SMF 9 one ends The other end of the SMF 9 is connected to the first output port of the first four-port coupler 8, and the second output port of the first four-port coupler 8 is used as the extraction port of another part of the Brillouin pump light and the second four-port The first input port of the coupler 11 is connected.

Described cascaded resonator is used to produce the second wavelength laser, comprises: the second four-port coupler 11, the second isolator 13 and NZDSF 12, wherein: the second four-port coupler 11 is that the coupling ratio is 50/50 Four-port coupler, its first input port is connected with the second output port of the first four-port coupler 8, and the second input port of the second four-port coupler 11 is connected with the second isolator 13 input , the output end of the second isolator 13 is connected to one end of the NZDSF 12, the other end of the NZDSF 12 is connected to the first output port of the second four-port coupler 11, and the second output port of the second four-port coupler 11 is vacant.

The wavelength of the DFB single-frequency laser 1 is 1575nm.

The maximum output power of the first 980nm pump source 2 is 330mW, the maximum output power of the second 980nm pump source 6 is 250mW, and the power of the two 980nm pump sources can be continuously adjusted.

The length of the ytterbium-doped optical fiber 4 is 7.5m.

The length of the SMF 9 is 300m, and the corresponding Brillouin frequency shift is 11.01GHz.

The length of the NZDSF 12 is 350m, and the corresponding Brillouin frequency shift is 10.895GHz.

During the work of this embodiment, the output signal optical power of the DFB single-frequency laser 1 is adjusted to the maximum (8mW), the output power of the two 980nm pump sources is adjusted to the maximum, and the power of the signal light rises to 160mW, the excess 980nm pump light is filtered out by the fiber circulator 7 and then input into two resonant cavities as the Brillouin pump light. The optical resonant cavity and the cascaded resonant cavity respectively excite Brillouin lasers of different wavelengths, and finally output to the photodetector 14 through the third port of the fiber circulator 7 for beating frequency. The frequency of the beating frequency microwave signal is 115.0MHz, and its The graph is shown in Fig. 3(e).

Example 6

As shown in Figure 1, the present embodiment includes: DFB single-frequency laser 1, thulium-doped fiber amplifier, fiber circulator 7, optical resonant cavity, cascaded resonant cavity, photodetector 14 and spectrum analyzer 15, wherein: DFB single-frequency The laser 1 is connected to the input end of the thulium-doped fiber amplifier to amplify the single-frequency laser signal output by the DFB single-frequency laser 1. The output end of the thulium-doped fiber amplifier is connected to the first port of the fiber circulator 7, and its second port is connected to the optical resonance The optical resonator is connected to the cascade resonator, the amplified single-frequency laser is sequentially input into the optical resonator and the cascade resonator through the second port of the circulator 7, and the third port of the fiber circulator outputs a dual-wavelength Bri The third port of the laser signal of the deep fiber laser is connected to the photodetector 14 to beat the laser signal, and the photodetector 14 is connected to the spectrum analyzer 15 to measure the microwave signal obtained by the beat frequency.

The thulium-doped fiber amplifier is used to amplify the single-frequency laser signal output by the DFB single-frequency laser 1 as Brillouin pumping light, including: the first 1064nm pumping source 2, the second 1064nm pumping source 6, the first WDM 3, the second WDM 5, and TDF (thulium-doped fiber) 4, wherein: one sub-wave end of the first WDM 3 is connected to the DFB single-frequency laser 1, and the first 1064nm pump source 2 is connected to the other end of the first WDM 3 The demultiplexing terminal is connected, the multiplexing terminal of the first WDM 3 is connected to one end of the TDF 4, the other end of the TDF 4 is connected to the multiplexing terminal of the second WDM 5, and the demultiplexing terminal of the second WDM 5 is connected to the second 1064nm pump source 6 are connected, and the multiplex end of the second WDM 5 is connected with the 1 port of the optical fiber circulator 7 as the output port of the thulium-doped fiber amplifier.

Described optical resonant cavity is used for producing first wavelength laser, comprises: first four-port coupler 8, first isolator 10 and DSF 9, wherein: described first four-port coupler 8 is that coupling ratio is 50/ The four-port coupler of 50, its first input port is connected with the second port of optical fiber circulator 7, and the second input port is connected with the input end of the first isolator 10, and the output end of the first isolator 10 is connected with DSF 9 one ends The other end of the DSF 9 is connected to the first output port of the first four-port coupler 8, and the second output port of the first four-port coupler 8 is used as the extraction port of another part of the Brillouin pump light and the second four-port The first input port of the coupler 11 is connected.

Described cascaded resonator is used for producing the second wavelength laser, comprises: the second four-port coupler 11, the second isolator 13 and SMF 12, wherein: the second four-port coupler 11 is that the coupling ratio is 50/50 Four-port coupler, its first input port is connected with the second output port of the first four-port coupler 8, and the second input port of the second four-port coupler 11 is connected with the second isolator 13 input , the output end of the second isolator 13 is connected to one end of the SMF 12, the other end of the SMF 12 is connected to the first output port of the second four-port coupler 11, and the second output port of the second four-port coupler 11 is vacant.

The wavelength of the DFB single-frequency laser 1 is 1510nm.

The maximum output power of the first 1064nm pump source 2 is 300mW; the maximum output power of the second 1064nm pump source 6 is 250mW, and the power of the two pump sources can be continuously adjusted.

The length of the thulium-doped optical fiber 4 is 8m.

The said DSF 9 has a length of 200m, and its corresponding Brillouin frequency shift is 10.718GHz.

The length of the SMF 12 is 300m, and its corresponding Brillouin frequency shift is 11.01GHz.

During the work of this embodiment, the output signal optical power of the DFB single-frequency laser 1 is adjusted to the maximum (10mW), the output power of the two 1064nm pump sources is adjusted to the maximum, and the power of the signal light rises to 180mW, and then the redundant 1064nm pump light is filtered by the fiber circulator 7 and then input into two cascaded resonators as Brillouin pump light. Finally, through the third port of the optical fiber circulator 7, it is output to the photodetector 14 for beating frequency. The frequency of the beating frequency microwave signal is 290.0 MHz, and its frequency spectrum is shown in FIG. 3(f).

Claims (7)

1. photoproduction microwave device based on the dual wavelength Brillouin optical fiber laser, comprise: the DFB single frequency laser, optical fiber circulator, photodetector and frequency spectrograph, it is characterized in that, also comprise: fiber amplifier, optical resonator and cascade resonator, wherein: the DFB single frequency laser links to each other with fiber amplifier and transmits the single-frequency laser signal, the fiber amplifier single-frequency laser signal of transmission after amplifying that link to each other with first port of optical fiber circulator, second port of the optical fiber circulator single-frequency laser signal of transmission after amplifying that link to each other with optical resonator, the optical resonator single-frequency laser signal of transmission after amplifying that link to each other with cascade resonator, the 3rd port of optical fiber circulator links to each other with photodetector and transmits the dual-wavelength laser signal, and photodetector links to each other with frequency spectrograph and transmits the beat frequency microwave signal.

2. the photoproduction microwave device based on the dual wavelength Brillouin optical fiber laser according to claim 1, it is characterized in that, described fiber amplifier comprises: first pumping source, second pumping source, the one WDM, the 2nd WDM and doped fiber, wherein: first pumping source links to each other with the partial wave end of a WDM and transmits pump light, the DFB single frequency laser links to each other with another partial wave end of a WDM and transmits the single-frequency laser signal, the one WDM close the ripple end link to each other with an end of doped fiber the transmission laser signal, the other end of doped fiber and the 2nd WDM close the ripple end transmission laser signal that links to each other, the partial wave end of the 2nd WDM links to each other with second pumping source and transmits pump light, and another partial wave end of the 2nd WDM links to each other with first port of optical fiber circulator with the single-frequency laser signal after the transmission amplification.

3. the photoproduction microwave device based on the dual wavelength Brillouin optical fiber laser according to claim 2 is characterized in that, described doped fiber is a kind of in Er-doped fiber, Yb dosed optical fiber and the thulium doped fiber.

4. the photoproduction microwave device based on the dual wavelength Brillouin optical fiber laser according to claim 1, it is characterized in that, described optical resonator comprises: the one or four port coupler, first isolator and first optical fiber, wherein: the first input end of the one or four port coupler links to each other with second port of optical fiber circulator, second input of the one or four port coupler links to each other with the input of first isolator, the output of first isolator links to each other with an end of first optical fiber, the other end of first optical fiber links to each other with first output of the one or four port coupler, and second output of the one or four port coupler links to each other with cascade resonator.

5. the photoproduction microwave device based on the dual wavelength Brillouin optical fiber laser according to claim 4, it is characterized in that described first optical fiber is a kind of in dispersion compensating fiber, dispersion shifted optical fiber, non-zero dispersion displacement optical fiber, monomode fiber and the highly nonlinear optical fiber.

6. the photoproduction microwave device based on the dual wavelength Brillouin optical fiber laser according to claim 1, it is characterized in that, described cascade resonator produces and comprises: the two or four port coupler, second isolator and second optical fiber, wherein: the first input end of the two or four port coupler links to each other with second output of the one or four port coupler, second input of the two or four port coupler links to each other with the input of second isolator, the output of second isolator links to each other with an end of second optical fiber, the other end of second optical fiber links to each other with first output of the two or four port coupler, and second output of the two or four port coupler is vacant.

7. the photoproduction microwave device based on the dual wavelength Brillouin optical fiber laser according to claim 6, it is characterized in that described second optical fiber is a kind of in dispersion compensating fiber, dispersion shifted optical fiber, non-zero dispersion displacement optical fiber, monomode fiber and the highly nonlinear optical fiber.

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