The full optical fiber Mode-locked laser of a kind of dual resonant cavity device
Technical field
The full optical fiber Mode-locked laser device that the invention discloses a kind of splitter with dual resonance cavity structure, belongs to laser technology, fiber optics and non-linear optical field.
Background technology
Fiber laser has the advantages such as volume is little, lightweight, conversion efficiency is high, output beam quality is good, has obtained in recent years fast development.Ultrashort pulse fiber laser is with its good beam quality, unrivaled heat dissipation characteristics, electro-optical efficiency, compact apparatus structure, stable laser activity and progressively obtain increasing user's favor and the market share compared with low maintenance operation expense in fields such as materials processing, laser medicine, industrial manufacture, national defense and military and scientific researches efficiently, and further becomes the focus of each research institution's research and development.
In the research of current mode locked fiber laser, the method that obtains mode locking pulse mainly contains active mode locking and passive mode locking technology.Active mode locking need to be used the control of additional modulator, can make light path design more complicated, and cost is higher, is unfavorable for industrialized development.Passive mode locking does not need to introduce external signal and produces pulse, normally a saturable absorber is placed in laser cavity, utilize its quick saturable absorption characteristic to cause the automodulation of light wave, the characteristic that to be transmitance increase with the increase of light intensity, light intensity is little compared with the loss when the saturable absorber of strong part, and transmitance is high; Light intensity compared with weak part during by saturable absorber loss large, transmitance is low, thereby produces pulse output.
At present the most frequently used saturable absorber is semiconductor saturable absorbing mirror (SESAM), but domestic cannot the production of SESAM can only dependence on import, has limited the reduction of optical fiber mode locked laser production cost.Development along with new material, Graphene, graphene oxide, carbon nano-tube (SWNT), topological insulator have all shown good saturable absorption characteristic, use new material as the mode locked fiber laser of saturable absorber, can break away from the dependence to external import SESAM in domestic ultrashort pulse fiber laser industry, break blockade on new techniques, make product have better promotion prospect, strengthened its industrial competition.
Summary of the invention
In order to solve, system complex in Active Mode-locked Fiber Laser, cost are high, poor anti jamming capability; The problems such as semiconductor saturable absorbing mirror (SESAM) manufacture craft is difficult simultaneously, production cost is high, the object of the invention is to based on splitter with dual resonance cavity structure, utilize new material saturable absorber to realize passive mode locking, full fiberize design is without extra modulation device, greatly reduce the loss of resonator, realize highly integrated stabilized lasers system.
For achieving the above object, it is the full optical fiber Mode-locked laser of a kind of dual resonant cavity device that the present invention adopts following technical scheme, and this laser comprises pumping and relevant apparatus, laserresonator, gain fibre, saturable absorption device, laser output device and other servicing unit.
Pumping and relevant apparatus comprise pumping source, optical-fiber bundling device or wavelength division multiplexer; Laserresonator comprises that reflection-type optical fiber Bragg grating comprises the first reflection-type optical fiber Bragg grating, the second reflection-type optical fiber Bragg grating, the 3rd reflection-type optical fiber Bragg grating, the 4th reflection-type optical fiber Bragg grating or total reflective mirror.
Gain fibre comprises the first gain fibre, the second gain fibre; Wherein, the first gain fibre is placed in resonant cavity II, and the second gain fibre is placed in resonant cavity II exterior resonant cavity I; Saturable absorption element comprises saturable absorber; Laser output device comprises optical isolator, circulator or beam splitter; Other servicing unit comprises filter.
Laserresonator can be linear or loop configuration; The resonant cavity of whole laser is divided into resonant cavity I resonant cavity II two parts, the exocoel that wherein resonant cavity I is laser, the inner chamber that resonant cavity II is laser; Resonant cavity I is comprised of linear resonant cavity or ring resonator; Resonant cavity II is comprised of linear resonant cavity; Each of resonant cavity I and resonant cavity II is to being equipped with gain fibre between reflection-type optical fiber Bragg grating; Wherein, saturable absorber is placed in resonant cavity II, it has quick saturable absorption characteristic, the characteristic that to be transmitance increase with the increase of light intensity, when the part that light intensity is stronger is passed through saturable absorber, the little transmitance of loss is high, light intensity compared with weak part during by saturable absorber loss large, transmitance is low, thereby produces pulse output; First pump light is injected in the gain fibre of resonant cavity I and is produced continuous laser, the laser producing subsequently enters the gain fibre of pump cavity II in resonant cavity II, and inhale protecting and absorption generation pulse laser of element by saturable, this pulse laser again enters in resonant cavity I and is further amplified afterwards, finally by laser output device output high-power pulse laser.
When being linear resonance cavity configuration, the first reflection-type optical fiber Bragg grating and the second reflection-type optical fiber Bragg grating form resonant cavity II, comprise the first gain fibre and saturable absorption element in resonant cavity II; The 3rd reflection-type optical fiber Bragg grating and the 4th reflection-type optical fiber Bragg grating form resonant cavity I, in resonant cavity II exterior resonant cavity I, comprise the second gain fibre; Or, in device, form the 3rd reflection-type optical fiber Bragg grating of resonant cavity I or any one of the 4th reflection-type optical fiber Bragg grating and can replace forming resonant cavity I by total reflective mirror, other the first reflection-type optical fiber Bragg grating and the 3rd reflection-type optical fiber Bragg grating can also replace forming resonant cavity I resonant cavity II by total reflective mirror 12 simultaneously.
When being annular resonance cavity configuration, by the second gain fibre, the 3rd reflection-type bragg grating and circulator, form annular chamber, i.e. resonant cavity I; The first reflection-type optical fiber Bragg grating and the second reflection-type optical fiber Bragg grating form resonant cavity II, comprise the first gain fibre and saturable absorption element in resonant cavity II.
Pumping source produces pump light, by optical-fiber bundling device or wavelength division multiplexer, is coupled in resonant cavity I, under the effect of the second gain fibre 4, produces continuous laser; The continuous laser that resonant cavity I produces afterwards enters pumping the first gain fibre in resonant cavity II, and be subject to can protecting with the effect of absorber element and producing pulse laser in resonant cavity II, the pulse laser that resonant cavity II produces afterwards enters the amplification obtaining in resonant cavity I again, finally by laser output device, realizes high power pulsed laser and exports.
Described reflection-type optical fiber Bragg grating is a kind of diffraction grating that the refractive index generation axial cyclic modulation of fiber core is formed by certain method, and its reflectivity and reflection wavelength can customize on demand.The first described reflection-type optical fiber Bragg grating and the second reflection-type optical fiber Bragg grating adopt Same Wavelength parameter, and reflectivity can be different; The 3rd reflection-type optical fiber Bragg grating and the 4th reflection-type optical fiber Bragg grating adopt Same Wavelength parameter, and reflectivity can be different; Described optical-fiber bundling device can also change wavelength division multiplexer into; Described the first reflection-type optical fiber Bragg grating and the 3rd reflection-type optical fiber Bragg grating can also change total reflective mirror into, the reflectivity of the first reflection-type optical fiber Bragg grating, the second reflection-type optical fiber Bragg grating, the 3rd reflection-type optical fiber Bragg grating, the 4th reflection-type optical fiber Bragg grating and total reflective mirror is R, wherein 0<R<1.
In described annular resonance cavity configuration, the second gain fibre can also be arranged between the common port and the 3rd Fiber Bragg Grating FBG of circulator; Described the second gain fibre can also be arranged between the incident end and the second Fiber Bragg Grating FBG of circulator; The second described gain fibre can also be arranged between the exit end of circulator and the common port of division multiplexer; Described wavelength division multiplexer can also change optical-fiber bundling device into.
In described annular resonance cavity configuration, optical isolator also can be put between the first reflection-type optical fiber Bragg grating and the second gain fibre, and after optical isolator, add beam splitter, simultaneously described circulator, the 3rd reflection-type optical fiber Bragg grating is replaceable is filter.
Described pumping source is semiconductor laser, solid state laser, gas laser, fiber laser or Raman laser, and the scope of the centre wavelength of output pump light is: 700nm-2000nm.
Described the first gain fibre and the second gain fibre are optical fiber or the photonic crystal fibers that is mixed with rare earth element, and wherein the rare earth element of doping is one or more in ytterbium (Yb), erbium (Er), holmium (Ho), thulium (Tm), samarium (Sm), bismuth (Bi).
Described saturable absorber is a kind of in Graphene, graphene oxide, carbon nano-tube, topological insulator.
Described pump mode is the single-ended pumping of fibre core, fibre core both-end pumping, the single-ended pumping of covering or covering both-end pumping.
Described optical-fiber bundling device is a kind of in polarized light beam combining device or non-polarized light bundling device.
The splitting ratio of described fiber optic splitter is between 0 to 1.
Described filter is a kind of in melting cone fiber filter, Fabry-Perot filter, multilayer thin-film-filter, Mach-Zehnder interference filter, body grating filter, array waveguide grating filter (AWG), fiber grating filter, acousto-optic tunable filter.
Compared with prior art, the present invention has following beneficial effect.
1, the present invention utilizes gain fibre and saturable absorber to produce ultrashort laser pulse in conjunction with splitter with dual resonance cavity structure, does not need extraneous additional modulation source, full optical fiber design.
2, the present invention adopts a kind of as saturable absorber in Graphene, graphene oxide, carbon nano-tube, topological insulator, and its quick saturable absorption characteristic can produce ultrashort pulse output.
3, simplicity of design of the present invention, compact conformation, ultra-short pulse laser that simultaneously can output stability is high, pulse energy is large, is easy to realize industrialization.
Accompanying drawing explanation
Fig. 1 is the full optical fiber Mode-locked laser device basic principle figure of splitter with dual resonance cavity structure.
Fig. 2 is the schematic diagram of resonant cavity while being linear structure.
Schematic diagram when Fig. 3 is total reflective mirror replacement reflection-type optical fiber Bragg grating.
Fig. 4 is the schematic diagram of resonant cavity while being loop configuration.
Fig. 5 is the full optical fiber Mode-locked laser device work of embodiment 1 schematic diagram.
Fig. 6 is the full optical fiber Mode-locked laser device work of embodiment 2 schematic diagram.
Fig. 7 is the full optical fiber Mode-locked laser device work of embodiment 3 schematic diagram.
In figure: 1, pumping source, 2, optical-fiber bundling device, the 3, first gain fibre, 4, the second gain fibre, 5, saturable absorber, the 6, first reflection-type optical fiber Bragg grating, 7, the second reflection-type optical fiber Bragg grating, the 8, the 3rd reflection-type optical fiber Bragg grating, the 9, the 4th reflection-type optical fiber Bragg grating, 10, optical isolator, 11, circulator, 12, total reflective mirror, 13, beam splitter, 14, filter, 15, wavelength division multiplexer.
Embodiment
Below in conjunction with drawings and Examples, the present invention is described in further detail.
As Figure 1-4, a kind of full optical fiber Mode-locked laser device of splitter with dual resonance cavity structure, this laser comprises pumping and relevant apparatus, laserresonator, gain fibre, saturable absorption element, laser output device and other servicing unit.
Laserresonator can be linear or loop configuration; The resonant cavity of whole laser is divided into resonant cavity I resonant cavity II two parts, the exocoel that wherein resonant cavity I is laser, the inner chamber that resonant cavity II is laser; Resonant cavity I is comprised of linear resonant cavity or ring resonator; Resonant cavity II is comprised of linear resonant cavity; Each of resonant cavity I and resonant cavity II is to being equipped with gain fibre between reflection-type optical fiber Bragg grating; Wherein, saturable absorption element is placed in resonant cavity II, it has quick saturable absorption characteristic, the characteristic that to be transmitance increase with the increase of light intensity, when the part that light intensity is stronger is passed through saturable absorber, the little transmitance of loss is high, light intensity compared with weak part during by saturable absorber loss large, transmitance is low, thereby produces pulse output; First pump light is injected in the gain fibre of resonant cavity I, the laser producing enters in resonant cavity II, the gain fibre of the laser pumping resonant cavity II that resonant cavity I produces, and produce pulse laser by protecting with absorption of saturable absorption element, this pulse laser again enters in resonant cavity I and is amplified afterwards, finally by laser output device output high-power pulse laser.
Pumping and relevant apparatus comprise pumping source 1, optical-fiber bundling device 2 or wavelength division multiplexer 15; Laserresonator comprises that reflection-type optical fiber Bragg grating comprises the first reflection-type optical fiber Bragg grating 6, the second reflection-type optical fiber Bragg grating 7, the 3rd reflection-type optical fiber Bragg grating 8, the 4th reflection-type optical fiber Bragg grating 9 or total reflective mirror 12.
Gain fibre comprises the first gain fibre 3, the second gain fibre 4; Wherein, the first gain fibre is placed in resonant cavity II, and the second gain fibre 4 is placed in resonant cavity II exterior resonant cavity I; Saturable absorption element comprises saturable absorber 5; Laser output device comprises optical isolator 10, circulator 11 or beam splitter 13; Other servicing unit comprises filter 14.
When being linear resonance cavity configuration, the first reflection-type optical fiber Bragg grating 6 and the second reflection-type optical fiber Bragg grating 7 form resonant cavity II; In resonant cavity II, comprise the first gain fibre 3 and saturable absorber 5; The 3rd reflection-type optical fiber Bragg grating 8 and the 4th reflection-type optical fiber Bragg grating 9 form resonant cavity I; Outside resonant cavity II and in resonant cavity I, comprise the second gain fibre 4; In device, form the 3rd reflection-type optical fiber Bragg grating 7 of resonant cavity I or any one of the 4th reflection-type optical fiber Bragg grating 8 and can replace forming resonant cavity I by total reflective mirror 12.Other the first reflection-type optical fiber Bragg grating 6 and the 3rd reflection-type optical fiber Bragg grating 8 can replace forming resonant cavity I resonant cavity II by total reflective mirror 12 simultaneously.
When being annular resonance cavity configuration, the second gain fibre 4, the 3rd reflection-type bragg grating 8 and circulator 11 or composition annular chamber, i.e. resonant cavity I; The first reflection-type optical fiber Bragg grating 6 and the second reflection-type optical fiber Bragg grating 7 form resonant cavity II, comprise the first gain fibre 3 and saturable absorber 5 in resonant cavity II.
Pumping source 1 produces pump light, by optical-fiber bundling device 2 or wavelength division multiplexer 15, is coupled in resonant cavity I, under the effect of the second gain fibre 4, produces continuous laser; The continuous laser that resonant cavity I produces afterwards enters pumping the first gain fibre 3 in resonant cavity II again, and be subject to can protecting with the effect of absorber 5 and producing pulse laser in resonant cavity II, the pulse laser that resonant cavity II produces afterwards enters resonant cavity I again, the amplification obtaining in resonant cavity I, finally realizes high power pulsed laser by laser output device and exports.
Described reflection-type optical fiber Bragg grating is a kind of diffraction grating that the refractive index generation axial cyclic modulation of fiber core is formed by certain method, and its reflectivity and reflection wavelength can customize on demand.The first described reflection-type optical fiber Bragg grating 6 and the second reflection-type optical fiber Bragg grating 7 adopt Same Wavelength parameter, and reflectivity can be different; The 3rd reflection-type optical fiber Bragg grating 8 and the 4th reflection-type optical fiber Bragg grating 9 adopt Same Wavelength parameter, and reflectivity can be different;
Described optical-fiber bundling device 2 can also change wavelength division multiplexer 15 into; Described the first reflection-type optical fiber Bragg grating 6 and the 3rd reflection-type optical fiber Bragg grating 8 can also change total reflective mirror 12 into, the reflectivity of the first reflection-type optical fiber Bragg grating 6, the second reflection-type optical fiber Bragg grating 7, the 3rd reflection-type optical fiber Bragg grating 8, the 4th reflection-type optical fiber Bragg grating 9 and total reflective mirror 12 is R, wherein 0<R<1.
In described annular resonance cavity configuration, the second gain fibre 4 can also be arranged between the common port and the 3rd Fiber Bragg Grating FBG 8 of circulator 11; Described the second gain fibre 4 can also be arranged between the incident end and the second Fiber Bragg Grating FBG 7 of circulator 11; The second described gain fibre 4 can also be arranged between the exit end of circulator 11 and the common port of division multiplexer 15; Described wavelength division multiplexer 15 can also change optical-fiber bundling device 2 into.
In described annular resonance cavity configuration, optical isolator 10 also can be put between the first reflection-type optical fiber Bragg grating 6 and the second gain fibre 4, and after optical isolator 10, add beam splitter 13, simultaneously described circulator 11, the 3rd reflection-type optical fiber Bragg grating 8 is replaceable is filter 14.
Described pumping source 1 is semiconductor laser, solid state laser, gas laser, fiber laser or Raman laser, and the scope of the centre wavelength of output pump light is: 700nm-2000nm.
Described the first gain fibre 3 and the second gain fibre 4 are optical fiber or the photonic crystal fibers that are mixed with rare earth element, and wherein the rare earth element of doping is one or more in ytterbium (Yb), erbium (Er), holmium (Ho), thulium (Tm), samarium (Sm), bismuth (Bi).
Described saturable absorber 5 is a kind of in Graphene, graphene oxide, carbon nano-tube, topological insulator.
Described pump mode is the single-ended pumping of fibre core, fibre core both-end pumping, the single-ended pumping of covering or covering both-end pumping.
Described optical-fiber bundling device 2 is a kind of in polarized light beam combining device or non-polarized light bundling device.
The splitting ratio of described fiber optic splitter 13 is between 0 to 1.。
Described filter 14 is a kind of in melting cone fiber filter, Fabry-Perot filter, multilayer thin-film-filter, Mach-Zehnder interference filter, body grating filter, array waveguide grating filter (AWG), fiber grating filter, acousto-optic tunable filter.
Embodiment 1
As shown in Figure 5, in figure, pumping source 1 is the semiconductor laser diode of 976nm for selecting centre wavelength; Optical-fiber bundling device 2 is for can select (2+1) * 1 pump signal bundling device, as 6/125 type or 20/125 type; 3, the 4th, rare earth doped fiber, the high-performance Yb dosed optical fiber that can select U.S. Nufern company to produce; The 5th, saturable absorber, can select Graphene, carbon nano-tube or topological insulator; The first reflection-type optical fiber Bragg grating 6, the second reflection-type optical fiber Bragg grating 7, the 3rd reflection-type optical fiber Bragg grating 8, optional type or the part reflection-type grating of being all-trans of the 4th reflection-type optical fiber Bragg grating 9, reflectivity is R, wherein 0<R<1; The optional polarization independent optical isolator of optical isolator 10.
Pump light enters into the second gain fibre 4 by the pumping end of optical-fiber bundling device 2, then arrive the 4th reflection-type optical fiber Bragg grating 9, its reflectivity is R(0<R<1), the light of this central wavelength can be reflected back, reverberation is successively through the second gain fibre 4, optical-fiber bundling device 2, the second reflection-type optical fiber Bragg grating 7, the rear arrival saturable absorber 5 of the first gain fibre 3, its quick saturable absorption characteristic, the characteristic that to be transmitance increase with the increase of light intensity, when light intensity is passed through saturable absorber compared with strong part, loss is little, transmitance is high, when light intensity is passed through saturable absorber compared with weak part, loss is large, transmitance is low, thereby produce pulse output, pulse laser arrives successively the first reflection-type optical fiber Bragg grating 6 and the 3rd reflection-type optical fiber Bragg grating 8 after saturable absorber 5, between the first reflection-type optical fiber Bragg grating 6 and the second reflection-type optical fiber Bragg grating 7, form resonant cavity II, between the 3rd reflection-type optical fiber Bragg grating 8 and the 4th reflection-type optical fiber Bragg grating 9, form resonant cavity I, splitter with dual resonance cavity structure can make laser operation more stable, the energy producing is larger, meet the laser produced under the condition of laser generation after the 3rd reflection-type optical fiber Bragg grating 8 from optical isolator 10 outputs.
Embodiment 2
As shown in Figure 6, in figure, pumping source 1 is the semiconductor laser diode of 976nm for selecting centre wavelength; Optical-fiber bundling device 2 is for can select (2+1) * 1 pump signal bundling device, as 6/125 type or 20/125 type; 3, the 4th, rare earth doped fiber, the high-performance Yb dosed optical fiber that can select U.S. Nufern company to produce; The 5th, saturable absorber, can select Graphene, carbon nano-tube or topological insulator; The first reflection-type optical fiber Bragg grating 6, the second reflection-type optical fiber Bragg grating 7, optional type or the part reflection-type grating of being all-trans of the 3rd reflection-type optical fiber Bragg grating 8, reflectivity is R, wherein 0<R<1; The optional polarization independent optical isolator of optical isolator 10; With total reflective mirror 12, replace the 4th reflection-type optical fiber Bragg grating 9.
Pump light enters into the second gain fibre 4 by the pumping end of optical-fiber bundling device 2, then arrive total reflective mirror 12, its reflectivity is R(0<R<1), the light being reflected arrives saturable absorber 5 successively after the second gain fibre 4, optical-fiber bundling device 2, the second reflection-type optical fiber Bragg grating 7, the first gain fibre 3, its quick saturable absorption characteristic, the characteristic that to be transmitance increase with the increase of light intensity, light intensity is little compared with the loss when the saturable absorber of strong part, and transmitance is high, when light intensity is passed through saturable absorber compared with weak part, loss is large, transmitance is low, thereby produce pulse output, pulse laser arrives successively the first reflection-type optical fiber Bragg grating 6 and the 3rd reflection-type optical fiber Bragg grating 8 after saturable absorber 5, between the first reflection-type optical fiber Bragg grating 6 and the second reflection-type optical fiber Bragg grating 7, form resonant cavity II, between the 3rd reflection-type optical fiber Bragg grating 8 and total reflective mirror 12, form resonant cavity I, splitter with dual resonance cavity structure can make laser operation more stable, the energy producing is larger, meet the laser produced under the condition of laser generation after the 3rd reflection-type optical fiber Bragg grating 8 from optical isolator 10 outputs.
Embodiment 3
As shown in Figure 7, to select centre wavelength be the semiconductor laser diode of 976nm to pumping source 1; Wavelength division multiplexer 15 is selected 980/1060nm single mode wavelength division multiplexer; The first gain fibre 3, the second gain fibre 4 are rare earth doped fibers, the high-performance Yb dosed optical fiber that can select U.S. Nufern company to produce; Saturable absorber 5 can be selected Graphene, carbon nano-tube or topological insulator; The first reflection-type optical fiber Bragg grating 6, optional type or the part reflection-type grating of being all-trans of the second reflection-type optical fiber Bragg grating 7, its reflectivity is R(0<R<1); The 10th, optical isolator, optional polarization independent optical isolator; Beam splitter 13 can be selected 90:10 fiber optic splitter; The optional 1um wave band of optical fiber filter 14 narrow band filter.
Pump light is held by the 980nm of wavelength division multiplexer 15, enter into the second gain fibre 4, through filter 14, select to arrive beam splitter 13 after wavelength, outside 10% output cavity, 90% gets back in chamber, by reaching saturable absorber 5 after the second reflection-type optical fiber Bragg grating 7 and the first gain fibre 3, its quick saturable absorption characteristic, the characteristic that to be transmitance increase with the increase of light intensity, light intensity compared with strong part during by saturable absorber 5 loss little, transmitance is high; When light intensity is passed through saturable absorber 5 compared with weak part, loss is large, transmitance is low, thereby produce pulse output, pulse laser arrives reflection-type optical fiber Bragg grating 6 after saturable absorber 5, between reflection-type optical fiber Bragg grating 6 and reflection-type optical fiber Bragg grating 7, form resonant cavity II, connect afterwards optical isolator 10, the 1060nm end that optical isolator 10 other ends connect wavelength division multiplexer 15 forms annular chamber, this annular chamber is resonant cavity I, exports meeting the laser of producing under the condition of laser generation after beam splitter 13.