CN102044827B - Optical fiber laser based on frequency pulling effect - Google Patents
Optical fiber laser based on frequency pulling effect Download PDFInfo
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- CN102044827B CN102044827B CN2010105688306A CN201010568830A CN102044827B CN 102044827 B CN102044827 B CN 102044827B CN 2010105688306 A CN2010105688306 A CN 2010105688306A CN 201010568830 A CN201010568830 A CN 201010568830A CN 102044827 B CN102044827 B CN 102044827B
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Abstract
一种激光技术领域的基于频率牵引效应的光纤激光器，包括：单频可调谐光源、光纤放大器、光学谐振腔和光纤拉伸装置，单频可调谐光源与光纤放大器相连传输单频激光信号，光纤放大器与光学谐振腔的输入端口相连传输放大后的单频激光信号，光学谐振腔中的单模光纤均匀地绕在光纤拉伸装置中且单模光纤的两端固定在光纤拉伸装置的两端。本发明通过对布里渊光纤激光器中作布里渊增益介质的光纤施加可调谐应力，改变其布里渊频移和布里渊增益曲线，进而通过频率牵引效应来精细调谐激光频率，结合泵浦光源的宽带调谐能力，实现了宽带且频率精细可调的光纤激光器，具有结构简单且成本低廉的优点。
A fiber laser based on the frequency pulling effect in the field of laser technology, comprising: a single-frequency tunable light source, an optical fiber amplifier, an optical resonator, and an optical fiber stretching device, the single-frequency tunable light source is connected to the fiber amplifier to transmit a single-frequency laser signal, and the optical fiber The amplifier is connected to the input port of the optical resonant cavity to transmit the amplified single-frequency laser signal. The single-mode fiber in the optical resonant cavity is evenly wound in the fiber stretching device and the two ends of the single-mode fiber are fixed on the two ends of the fiber stretching device. end. The invention applies tunable stress to the optical fiber used as the Brillouin gain medium in the Brillouin fiber laser, changes its Brillouin frequency shift and Brillouin gain curve, and then finely tunes the laser frequency through the frequency pulling effect, combined with pumping The broadband tuning capability of the light source realizes a fiber laser with broadband and finely adjustable frequency, and has the advantages of simple structure and low cost.
Description
Technical field
What the present invention relates to is a kind of device of laser technology field, specifically is a kind of broadband based on backlash, the meticulous adjustable fiber laser of frequency.
Background technology
The meticulous adjustable single frequency laser of broadband and frequency has widely to be used, like optical coherence image technique, sensor-based system, high meticulous spectrum analysis and dense wavelength division multiplexing system.In these all applications, the tuning capability of laser such as adjustable extent, tuned speed, particularly tuning precision are wherein crucial technology.Present stage, the adjustable extent of single frequency laser can reach hundred nanometers (nm) magnitude, and tuned speed also can reach (ns) magnitude of tens of nanoseconds, can satisfy application requirements basically.But the tuning precision of laser but is difficult to further improve.The reason one that tuning precision is difficult to be improved is the live width broad of main single frequency laser of present stage, is generally megahertz (MHz) magnitude like semiconductor laser, and fiber laser is generally tens of KHzs (kHz) magnitude; The 2nd, these lasers tuning all is based on the tuned optical method; Promptly in laserresonator, insert tunable optical filter and realize that laser frequency is tuning; Therefore its tuning precision will depend on the tuning precision of optical filter; And present stage tunable optical filter tuning precision be generally GHz (GHz) magnitude, so the tuned optical method be difficult to realize that laser superelevation fine frequency is tuning.
In the prior art, the fine tune of distributed Feedback (DFB) and distributed Bragg reflection (DBR) semiconductor single frequency laser is mainly through changing conductor temperature or regulating its injection current size and realize that its tuning precision can reach tens of MHz.But, therefore be difficult to further improve its tuning precision because the live width broad of its semiconductor single frequency laser is generally several MHz.And the output frequency of DFB and dbr semiconductor single frequency laser is easy to receive the influence of ambient temperature and disturbance, therefore will realize the accurate tuning complex laser frequency regulator that needs of laser frequency, increases system complexity and cost greatly.The tuning of optical fiber single frequency laser mainly is in resonant cavity, to insert tunable optical filter to realize that the tunable optical filter that present stage uses mainly contains tunable F-P cavity filter, tunable fiber grating filter etc.The tuning precision of these tunable optical filters is generally the GHz magnitude, so generally also be the GHz magnitude based on the tuning precision of the laser of this tuning methods.In order further to improve the tuning precision of optical fiber single frequency laser; Can in its resonant cavity, insert piezoelectric ceramic (PZT); Realize stretching or the compression of PZT through changing temperature or voltage, thereby the chamber of meticulous adjusting laserresonator is long, can realize the tuning precision of the tens of MHz of laser like this.
Through existing literature search is found; People such as the breadboard E.Alleria of gondola Elettra are at Europhysics Letters; 2010; The article that is entitled as " Tunability of a seeded free-electron laser through frequency pulling (realizing injecting the tuning of free electron laser through frequency pulling) " is disclosed on 89 (6), 64005 (P1-P5) (" European physics wall bulletin " 89 in 2010 rolled up 64,005 first pages to the 5th page of the 6th phases).This article has just been set forth backlash theoretically and has been had the possibility of realization free electron laser (FEL) frequency fine tuning, and does not prove from the experiment aspect.And notional result only shows in ultrashort pulse FEL, could pass through backlash and realize frequency tuning, and is then not all right in standard injected pulse FEL.
Summary of the invention
The present invention is directed to the above-mentioned deficiency that prior art exists; A kind of fiber laser based on backlash is provided; Through the optical fiber of making the brillouin gain medium in the Brillouin optical fiber laser is applied tunable stress, change its Brillouin shift and brillouin gain curve, and then come the fine tuning laser frequency through backlash; In conjunction with the wide-band tuning ability of pump light source, realized the meticulous adjustable fiber laser of broadband and frequency.The present invention does not need humorous optical filter of extra adjustable and laserresonator chamber length regulating device, has advantage simple in structure and with low cost.
The present invention realizes through following technical scheme; The present invention includes: single frequency tunable light source, fiber amplifier, optical resonator and optical-fiber drawing device; Wherein: the single frequency tunable light source 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 the input port of optical resonator, the monomode fiber in the optical resonator equably in optical-fiber drawing device and the two ends of monomode fiber be fixed on the two ends of optical-fiber drawing device.
Described single frequency tunable light source is a kind of in DFB single frequency tunable light source, DBR single frequency tunable light source, external cavity type semiconductor single frequency tunable light source, carbon dioxide single frequency tunable light source or the dyestuff single frequency tunable light source.
Described fiber amplifier is used to amplify the single-frequency laser signal of single frequency tunable light source output; Comprise: first pumping source, second pumping source, first wavelength division multiplexer (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 single frequency tunable light source 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 transmission pump light that links to each other with second pumping source, and another partial wave end of the 2nd WDM links to each other with the input port of optical resonator to transmit the single-frequency laser signal after the amplification as the output port of described fiber amplifier.
Described doped fiber is a kind of in Er-doped fiber, Yb dosed optical fiber or the thulium doped fiber.
Described optical resonator is used to produce the meticulous adjustable laser of frequency; Comprise: optical fiber circulator, optical fiber polarization controller, monomode fiber and three port coupler; Wherein: first port of optical fiber circulator links to each other with the output port of fiber amplifier as the input port of described optical resonator; Second port of optical fiber circulator links to each other with an end of optical fiber polarization controller; The other end of optical fiber polarization controller links to each other with monomode fiber one end, and the monomode fiber other end links to each other with first output port of three port coupler, and the first input end mouth of three port coupler links to each other with the 3rd port of optical fiber circulator; Second output port of three port coupler is vacant, as the output port of fiber laser.
Described monomode fiber is a kind of in dispersion compensating fiber, dispersion shifted optical fiber, non-zero dispersion displacement optical fiber, general single mode fiber or the highly nonlinear optical fiber.
Described optical-fiber drawing device is used for the monomode fiber of optical resonator is applied tunable stress; Comprise: first drum, second drum, one dimension translation stage and substrate; Wherein: first drum is fixed in the one dimension translation stage, and the one dimension translation stage is fixed in substrate, and second drum is fixed in substrate.Described monomode fiber one end is fixed on first drum, and the other end is fixed on second drum, and mid portion is equably around between first drum and second drum.
Operation principle of the present invention is: the single frequency tunable light source is as signal source; The single-frequency laser signal of its output is input in the optical resonator as Brillouin's pump light after fiber amplifier amplifies; When the Brillouin's pumping light power that injects surpasses resonant cavity stimulated Brillouin scattering threshold value; To form Brillouin laser in the resonant cavity, this moment, laser was a Brillouin optical fiber laser, and the frequency f of Brillouin laser is f=f
0-v
B(1)
Wherein: f
0Be Brillouin's pump light frequency, also be the output frequency of single frequency tunable light source, v
BFor Brillouin's pump light wavelength is λ
pThe time monomode fiber Brillouin shift, be v
B=2n υ
A/ λ
p(2)
Wherein: λ
p=c/ (nf
0) (3)
N is that monomode fiber is in pump wavelength
pThe refractive index at place, c is the light velocity in the vacuum.υ
ABe the velocity of sound in the optical fiber, it is only relevant with the character of optical fiber own, and has
Wherein: γ is the Young's modulus of fiber optic materials, and ρ is the volume density of fiber optic materials.When receiving tensile stress, optical fiber does the time spent, the velocity of sound υ in the optical fiber
ACan become big, Brillouin shift v
BAlso can become big.
Can know by (1) formula, as the Brillouin shift v of optical fiber
BIn the time of fixedly, the Brillouin laser frequency f receives Brillouin's pump light frequency f
0Control.In fact, the tuning range of Brillouin's pump light, tuned speed and tuning precision all will pass to Brillouin laser.Generally speaking, the tuning range of Brillouin's pump light can reach hundred nm magnitudes, so the tuning range of Brillouin laser also will reach hundred nm magnitudes.But the tuning precision of Brillouin's pump light generally has only 10 micromicrons (pm), also is the GHz magnitude, so rely on Brillouin's pump light merely, the tuning precision of Brillouin laser also can only reach the GHz magnitude.For the frequency of fine tuning Brillouin laser more, can apply tunable stress to the monomode fiber of doing the brillouin gain medium in the laserresonator through optical-fiber drawing device, change the velocity of sound υ in the optical fiber
AWith Brillouin shift v
B, and then fine tuning Brillouin laser frequency f.
The brillouin gain spectrum width of monomode fiber is generally 20～50MHz; In order to make Brillouin optical fiber laser operate in the single longitudinal mode state; Also be the output of strict guarantee laser single-frequency; The free spectrum width of laser will near or greater than the brillouin gain spectrum width, in the brillouin gain bandwidth, then can guarantee to have only single longitudinal mode vibration like this.Formula by the free spectrum width (FSR) of laser:
Can know that bigger in order to make FSR, the simplest method reduces the laserresonator length L exactly.When Brillouin's pump light frequency f
0In the time of fixedly, to making the monomode fiber stress application of brillouin gain medium in the laserresonator, with the Brillouin shift v that increases monomode fiber
B, also will change the position of its brillouin gain frequency spectrum.Backlash by laser can be known; Oscillation mode in the Brillouin optical fiber laser (single longitudinal mode) will certain distance along with moving of brillouin gain frequency spectrum on frequency axis, also be Brillouin optical fiber laser can be in certain scope continuous tuning.In a free spectrum width, based on the continuous adjustable extent Δ f of the Brillouin optical fiber laser of backlash be:
Wherein: σ
cBe the resonant cavity live width of Brillouin optical fiber laser, σ
gBrillouin gain spectrum width for monomode fiber.Generally speaking, so in the laser tuning process, will have the mode hopping phenomenon, also promptly there is the laser frequency jumping phenomenon less than FSR in Δ f.In a free spectrum width, the laser frequency sudden change size that mode hopping causes is (FSR-Δ f).
The characteristics of above-mentioned tuning methods are that it does not directly carry out tuning to laser frequency; But suc as formula shown in (1); It is tuning that it has the frequency of sound wave of remote-effects to carry out to laser frequency, and then realize the tuning of laser frequency, therefore is different from the traditional optical tuning methods; Above-mentioned laser tuning method can be thought based on the Acoustic treatment method, also promptly may be defined as acoustically tuned method.Because Brillouin shift (frequency of sound wave) size is generally the 10GHz magnitude, than little 4 magnitudes of optical frequency 200 Terahertzs (THz), so the tuning precision of acoustically tuned method will improve greatly, generally can reach tens of kHz magnitudes.
Compared with prior art; The invention has the beneficial effects as follows: compare with the laser that uses the traditional optical tuning methods, the tuning precision of the meticulous adjustable fiber laser of the broadband based on backlash, the frequency that the present invention realizes can improve three to four one magnitude.And need not use humorous optical filter of extra adjustable and laserresonator chamber length regulating device, can realize the meticulous adjusting of laser frequency, have advantage simple in structure and with low cost.
Description of drawings
Fig. 1 is a structural representation of the present invention;
Fig. 2 is the structural representation of three port coupler;
Fig. 3 is a laser output frequency fine tuning sketch map;
Wherein: 1 single frequency tunable light source, 2 first pumping sources, 3 the one WDM, 4 doped fibers, 5 the 2nd WDM, 6 second pumping sources, 7 optical fiber circulators, 8 optical fiber polarization controllers, 9 monomode fibers, 10 3 port coupler, 11 substrates, 12 one dimension translation stages, 13 first drums, 14 second drums, 15 first input end mouths, 16 first output ports, 17 second output ports.
Embodiment
Elaborate in the face of embodiments of the invention down, present embodiment provided detailed execution mode and concrete operating process, but protection scope of the present invention is not limited to following embodiment being to implement under the prerequisite with technical scheme of the present invention.
As shown in Figure 1; Present embodiment comprises: single frequency tunable light source 1, fiber amplifier, optical resonator and optical-fiber drawing device; Wherein: single frequency tunable light source 1 links to each other with the fiber amplifier input; To amplify the single-frequency laser signal of single frequency tunable light source 1 output, the output of fiber amplifier links to each other with the input of optical resonator, and the single-frequency laser signal after amplifying with input is made Brillouin's pump light.Monomode fiber 9 two ends in the fiber resonance cavity are separately fixed at the two ends of optical-fiber drawing device, the mid portion of monomode fiber 9 equably on the optical-fiber drawing device to apply tunable stress.
The single-frequency laser signal that described fiber amplifier is used to amplify 1 output of single frequency tunable light source is to make Brillouin's pump light; Comprise: first pumping source 2, second pumping source 6, a WDM 3, the 2nd WDM 5, doped fiber 4; Wherein: the partial wave port of a WDM 3 links to each other with single frequency tunable light source 1; First pumping source 2 links to each other with another partial wave port of a WDM 3; The ripple port that closes of the one WDM 3 links to each other with doped fiber 4 one ends; The other end of doped fiber 4 links to each other with the ripple port that closes of the 2nd WDM 5, and the partial wave port of the 2nd WDM 5 links to each other with second pumping source 6, and another partial wave port of the 2nd WDM 5 links to each other with the input port of optical resonator as the output port of fiber amplifier.
Described optical resonator is used to produce Brillouin laser; Comprise: optical fiber circulator 7; Optical fiber polarization controller 8, monomode fiber 9 and three port coupler 10, wherein: first port of optical fiber circulator 7 links to each other with the partial wave port of the 2nd WDM 5 as the input port of described optical resonator; Second port of optical fiber circulator 7 links to each other with a port of optical fiber polarization controller 8; The another port of optical fiber polarization controller 8 links to each other with a port of monomode fiber 9, and the another port of monomode fiber 9 links to each other with first output port of three port coupler 10, and the first input end mouth of three port coupler 10 links to each other with the 3rd port of optical fiber circulator 7; Second output port of three port coupler 10 is vacant, as the output port of Brillouin optical fiber laser.
Described optical-fiber drawing device is used for monomode fiber 9 is applied tunable stress; And then realize the fiber laser frequency tuning, comprising: substrate 11, one dimension translation stage 12, first drum 13 and second drum 14; Wherein: first drum 13 is fixed in one dimension translation stage 12; One dimension translation stage 12 is fixed in substrate 11, the second drums 14 and is fixed in substrate 11, and monomode fiber 9 one ends are fixed in first drum 13; Monomode fiber 9 other ends are fixed in second drum 14, and monomode fiber 9 mid portions are evenly around between first drum 13 and second drum 14.
The structural representation of described three port coupler is as shown in Figure 2.
Single frequency tunable light source 1 described in the present embodiment is an external cavity type semiconductor single frequency tunable light source, and tuning range is 1468-1589nm, and tuning precision is 10pm.
Described first pumping source, 2 output wavelengths are 980nm, and peak power output is 330mW, and second pumping source, 6 output wavelengths are 980nm, and peak power output is 250mW, and the power of two pumping sources can be regulated continuously.
Described doped fiber 4 is an Er-doped fiber, and length is 22m, and doping content is 400ppm.
Described monomode fiber 9 is common healthy and free from worry monomode fiber, and model is SMF-28, and length is 10m.
During present embodiment work; The Output optical power of single frequency tunable light source 1 is transferred to maximum (1mW); The power output of first pumping source 2 and second pumping source 6 is transferred to maximum; Simple signal light amplifies back power through fiber amplifier and rises to 208mW, again through being input to optical resonator as Brillouin's pump light behind the unnecessary 980nm pump light of optical fiber circulator 7 filterings.Stretch through 12 pairs of monomode fibers 9 of one dimension translation stage, can apply the stress of different sizes, and then can change the Brillouin shift size of monomode fiber 9, realize the meticulous adjusting of laser output frequency monomode fiber 9.Laser output frequency is as shown in Figure 3 with the variation sketch map that monomode fiber 9 stretches.As shown in Figure 3, in a free spectral range (20.1MHz) of laser, adjustable extent is 6.2MHz continuously, and the mode hopping size is 13.9MHz, and its tuning precision can reach 14.2kHz.
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| CN102522678A (en) * | 2011-12-14 | 2012-06-27 | 上海交通大学 | Tunable precision frequency photoproduction microwave apparatus based on cascade Brillouin laser |
| CN103972772B (en) * | 2014-04-24 | 2016-06-15 | 上海交通大学 | A kind of single frequency tunable 2 micrometer pulse fiber laser device |
| CN109286120A (en) * | 2018-11-13 | 2019-01-29 | 深圳市杰普特光电股份有限公司 | A kind of polarization-maintaining fiber laser |
| CN110932064A (en) * | 2019-11-07 | 2020-03-27 | 上海大学 | Optical fiber laser with orthogonal polarization mode selection output |
| CN118198844B (en) * | 2024-05-20 | 2024-07-23 | 山东省科学院激光研究所 | Control method and control system for wavelength stability of single-frequency fiber laser |
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| US6078716A (en) * | 1999-03-23 | 2000-06-20 | E-Tek Dynamics, Inc. | Thermally expanded multiple core fiber |
| US7817684B2 (en) * | 2006-11-16 | 2010-10-19 | Ofs Fitel Llc | Passively modelocked figure eight fiber laser |
| CN101728752B (en) * | 2008-10-22 | 2011-06-01 | 中国科学院半导体研究所 | A wavelength-tunable fiber laser |
| CN101667710B (en) * | 2009-10-09 | 2011-01-05 | 北京航空航天大学 | Tunable single-frequency single polarization fiber laser based on polarization-preserved fiber grating |
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