CN109193336A - Method for suppressing stimulated Brillouin scattering by fiber laser oscillator - Google Patents
Method for suppressing stimulated Brillouin scattering by fiber laser oscillator Download PDFInfo
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- CN109193336A CN109193336A CN201811270199.4A CN201811270199A CN109193336A CN 109193336 A CN109193336 A CN 109193336A CN 201811270199 A CN201811270199 A CN 201811270199A CN 109193336 A CN109193336 A CN 109193336A
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- optical fiber
- laser oscillator
- fiber grating
- fibre laser
- inclined optical
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/30—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range using scattering effects, e.g. stimulated Brillouin or Raman effects
- H01S3/302—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range using scattering effects, e.g. stimulated Brillouin or Raman effects in an optical fibre
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/06—Construction or shape of active medium
- H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
- H01S3/067—Fibre lasers
- H01S3/0675—Resonators including a grating structure, e.g. distributed Bragg reflectors [DBR] or distributed feedback [DFB] fibre lasers
Abstract
The invention provides a method for inhibiting stimulated Brillouin scattering by a fiber laser oscillator, which is characterized in that an inclined fiber grating is connected into a fiber laser oscillator cavity, and laser injected into the inclined fiber grating is filtered by utilizing the high loss of the inclined fiber grating in a Brillouin wave band so as to inhibit the stimulated Brillouin scattering. The inclined fiber grating has high loss in the Brillouin waveband, has a good effect of inhibiting backward Stokes signal light generated by the fiber laser oscillator, can improve the SBS threshold of the whole fiber laser oscillator, greatly reduces the risk of the high-power Stokes signal light to the fiber laser oscillator, and improves the performance of the fiber laser oscillator.
Description
Technical field
The invention belongs to fiber laser technology fields more particularly to a kind of fibre laser oscillator to inhibit excited Brillouin
The method of scattering.
Background technique
Optical fiber laser have high-efficient, good beam quality, small in size, non-maintaining, low operating cost, high light beam quality,
The advantages that running life is long, is easy to modulate, compact-sized, is widely used in fields such as military affairs, industry.But it is limited to non-linear effect
It answers, light injury and the problems such as fuel factor, further promotes single fiber laser output power and face great technological challenge.Therefore, it adopts
Become the widespread consensus for further promoting optical fiber laser output power with multi-fiber power combing.Wherein, spectrum beam combination is because of its system
Structure is simple, stability is good and is easily achieved and controls by common concern.To obtain the output of high power spectrum beam combination, to optical fiber
The power of laser, line width have special requirement.High power narrow linewidth optical fiber laser is to meet having for these special applications
Imitate light source.
Currently, high power narrow linewidth optical fiber laser is realized using master oscillation power amplification (MOPA) structure in the world
's.In MOPA structured optical fiber laser, seriously limited along with the thermotropic mode wild effect that the promotion of output power generates
The beam quality and output power of optical fiber laser are made.Using the high-capacity optical fiber laser of oscillator structure, due to optical fiber
Grating is different to the reflection kernel wavelength of high-order mode and low-order mode, for specific wavelength design oscillator to the basic mode of the wavelength
There is higher reflectivity, while lower to higher order mode reflectivity.Therefore, oscillator structure can suppression mode be to a certain degree
Stablize.In addition, being had using the high-capacity optical fiber laser of oscillator structure, structure is simple, stability is good, low in cost etc. excellent
Point has great development prospect.
For high power narrow linewidth fibre laser oscillator, since fiber lengths are longer, fiber core sectional area is smaller, when
After transimission power reaches certain level, it is easy to generate all kinds of nonlinear effects.In various nonlinear effects, excited Brillouin
The threshold value for scattering (SBS) is minimum, is the primary limiting factor that current narrow linewidth oscillator power is promoted.Stimulated Brillouin scattering
(SBS) effect can be generated in fiber oscillator device it is high-power after to Stokes light, cause oscillator delivery efficiency to decline, seriously
Influence the normal work of oscillator.Currently, being suggested to inhibit stimulated Brillouin scattering (SBS) there are many method, application
It is more mainly have increase optical fiber effective core area, using highly doped or large mode field optical fiber with reduce optical fiber effective length,
Broaden brillouin gain spectrum.Wherein, the above two are limited to the manufacture craft of optical fiber, and the bigger meeting of optical fiber mode fields area is so that mould
The threshold value of unstable (MI) effect of formula is lower, is unfavorable for the stability and power ascension of optical fiber amplification system, using still extremely having
Limit.By applying temperature, stress gradient broadens the method that brillouin gain spectrum inhibits stimulated Brillouin scattering (SBS), and control is difficult
It spends larger, and is easy to be influenced by extraneous factor, system is also more complicated.
Summary of the invention
In view of the defects existing in the prior art, the present invention provides a kind of fibre laser oscillator inhibition stimulated Brillouin scattering
Method.
To realize the above-mentioned technical purpose, the technical scheme is that
The method that fibre laser oscillator inhibits stimulated Brillouin scattering, by by inclined optical fiber grating incoming fiber optic laser
In oscillator chamber, using inclined optical fiber grating Brillouin's wave band high lossy, to injection inclined optical fiber grating in laser
It is filtered, to inhibit stimulated Brillouin scattering.Inclined optical fiber grating its Brillouin's wave band have high lossy, to optical fiber swash
The backward Stokes signal light that optical generator generates has preferable inhibitory effect, is able to ascend fibre laser oscillator entirety
SBS threshold, and to weaken significantly as high-power Stokes signal light risk caused by fibre laser oscillator, change
The performance of kind fibre laser oscillator.
Fibre laser oscillator of the invention can shake for forward pumping fibre laser oscillator, backward pump optical-fiber laser
Swing device or two directional pump fibre laser oscillator.Forward pumping fibre laser oscillator, backward pump fibre laser oscillator
And two directional pump fibre laser oscillator is divided according to oscillator pump mode difference.Fibre laser oscillator includes
Pump LD light source, pump combiner, high reflective grid, doped fiber, low reflective grid.
About the setting position of inclined optical fiber grating, the present invention provides following several technical solutions:
Before the intracavitary low reflective grid of fibre laser oscillator are arranged in inclined optical fiber grating.The inclined optical fiber grating is only
Erect and set, inclined optical fiber grating preparation on an individual optical fiber its both ends by way of welding respectively with doped fiber
The connection of the input terminal of output end and low reflective grid.Alternatively, in order to further decrease splice loss, splice attenuation, the inclined optical fiber grating and
Over the same fiber, wherein inclined optical fiber grating is located between the front and the two holding centainly of low reflective grid for low reflective grid preparation
Away to optimize oscillator performance.
After the intracavitary reflective grid of height of fibre laser oscillator are arranged in inclined optical fiber grating.The inclined optical fiber grating is only
Erect and set, inclined optical fiber grating preparation on an individual optical fiber its both ends by way of welding respectively with high reflective grid
The connection of the input terminal of output end and doped fiber.Alternatively, in order to further decrease splice loss, splice attenuation, the inclined optical fiber grating and
Over the same fiber, wherein inclined optical fiber grating is located between the rear and the two holding centainly of high reflective grid the reflective grid preparation of height
Away to optimize oscillator performance.
Inclined optical fiber grating is directly scribed on the intracavitary doped fiber of fibre laser oscillator.Since optical-fiber laser shakes
It is higher to swing device intra-cavity energy density, loss has large effect to its efficiency.During actually building fibre laser oscillator,
Fiber grating has encapsulated, and inconvenience carries out fiber grating inscription, can directly prepare inclined optical fiber grating on doped fiber, with
The loss of oscillation chamber is further decreased, delivery efficiency is improved and fibre laser oscillator inside excited Brillouin phenomenon is pressed down
System.
In the present invention: for high anti-grating operation at laser works wavelength, the reflectivity of high reflective grid is typically larger than 99%,
Three dB bandwidth is usually 2-4nm, is prepared on the identical optical fiber of same pump combiner its output optical fibre.Doped fiber should choose with
The doped fiber that high reflective grid match, is typically the LMA-YDF-20/400-M optical fiber of Nufern company.Low reflective grid it is anti-
The rate of penetrating is usually more than 10%, and three dB bandwidth is usually more than 1nm.The middle cardiac wave of low its central wavelength of reflective grid and high reflective grid
Long identical or its difference range with the central wavelength of high reflective grid is between ± 0.4nm.
It, can be by increasing inclined optical fiber grating number in fibre laser oscillator is intracavitary to further increase inhibitory effect
Purpose mode, to further increase inhibition ratio.I.e. by the identical inclined optical fiber grating of multiple parameters by way of welding each other
The intracavitary corresponding position of fibre laser oscillator is accessed after being cascaded.It, can by the control to inclined optical fiber grating number
To accomplish that inhibition ratio is adjusted flexibly.
Inclined optical fiber grating is to be presented periodic refractive index modulation along optical fiber axial direction in fibre core, but its grating planar
With optical fiber tangentially in certain inclination angle.It is preceding to the fibre core intermode with reverse transfers in addition to existing due to the presence of tilt angle
Coupling is outer, and there is also the cladding modes or radiation mode of the core mode of fl transmission and reverse transfers (assuming that cladding diameter is infinitely great
In the case of) between coupling.It will appear many discrete resonance peaks in the transmitted spectrum intermediate waves region of inclined optical fiber grating.These
Discrete resonance peak bandwidth in 0.2nm magnitude, can be used as fiber grating narrow-band filter.It in this way can will be special
The long core light of standing wave is filtered out into covering.In general, influence inclined optical fiber grating transmitted spectral characteristics because be known as screen periods,
Tilt angle, modulation depth etc. are balanced by the selection to these factors, its resonance peak wave-length coverage can be adjusted,
And it is used as fiber grating filter.It is analogous to the condition of resonance of Bragg fiber grating, for common Bragg light
Fine grating, the resonance wavelength for meeting Bragg diffraction conditions can indicate are as follows:
WhereinIt is the effective refractive index of core mode, ΛgIt is screen periods.It can be seen that screen periods determine grating
Central wavelength.For inclined optical fiber grating, Bragg resonance wavelength expression formula are as follows:
In formula, θ is inclined optical fiber grating tilt angle.Due to the presence at inclination angle, Bragg resonance wavelength can change
Become, while the core mode for having part fl transmission is coupled in the cladding mode of reverse transfer, resonance wavelength can be expressed as:
WhereinIt is the effective refractive index of the i-th rank cladding mode.
Screen periods determine raster center wavelength.Currently, often using operation wavelength 1,1.5,2 micro- for fibre laser oscillator
Rice, can realize the covering of inclined optical fiber grating operation wavelength by the adjustment to screen periods.With the increasing of tilt angle
Greatly, it may appear that more high-order cladding mode resonants spectrally show as resonance envelope and integrally move to shortwave direction, and bandwidth
Widen therewith, but the depth shallower of transmission spectrum.The modulation depth of inclined optical fiber grating directly determines the depth of transmission peaks, thoroughly
The depth for penetrating peak is to filter out the important indicator of Brillouin's Stokes signal light.The modulation depth of inclined optical fiber grating is stronger, transmission
Peak depth is deeper, it is meant that better to the filtration result of Brillouin's Stokes signal light.Inclined optical fiber grating can achieve most
Big modulation depth depends primarily on the photosensitive amount of optical fiber used by inscribing inclined optical fiber grating, and the photosensitive amount of optical fiber is bigger,
It is bigger to inscribe the attainable maximum percentage modulation of inclined optical fiber grating institute.Although optical fiber itself has light sensitivity, it is still desirable to logical
The mode of overload hydrogen can further enhance its light sensitivity, and it is different because of optical fiber concrete type to carry the hydrogen time.It is big for big core diameter
Mould field optical fiber is often 8 weeks.Therefore the filtration result that can reach according to actual needs treats the light for inscribing inclined optical fiber grating
Fibre selection is suitable to carry the hydrogen time.But the difficulty that excessive tilt angle can be such that inclined optical fiber grating inscribes increases, therefore wants
Tilt angle is reasonably selected according to required operation wavelength, to reach optimal filtration result.In general, when SBS effect occurs,
Spectrally Stokes signal light and signal light are spaced in 0.08nm magnitude, can be carried out according to this to the parameter of inclined optical fiber grating
It calculates.Typically for inclined optical fiber grating, it is contemplated that its effective refractive index desirable 1.443 after inclination, according to wavelength and period
Corresponding relationship λ=2neffΛ can calculate its screen periods of inclined optical fiber grating.For the tilt angle of inclined optical fiber grating, examine
Consider wavelength interval, inscribe the various factors such as complexity, generally takes between 4-6 °；Specific value should inscribe production according to practical
Inclined optical fiber grating spectrum out is accepted or rejected.
The generation of SBS effect can be described as pump light and Stokes signal light by acoustic wavefield carry out it is non-linear mutually
Effect.It can cause the generation of refractive-index grating in optical fiber when pumping light power reaches certain level, which passes through Prague
Diffraction scattering pump light, to Stokes signal light after formation.Backward Stokes signal light is interfered with pump light, by electroluminescent
Flex effect generates sound wave, the acoustic wavefield back scattering of modulated media refractive index and enhancing to pumping laser in turn.By inclining
Oblique fiber grating introduces the loss near Stokes signal light wavelength, even if the power density of pump light reaches in optical fiber laser
The Stokes signal light of generation is depleted by its power threshold, apparent stimulated Brillouin scattering phenomenon will not be generated, more
Apparent stimulated Brillouin scattering phenomenon can be just seen under high power level, to obtain higher SBS threshold.Therefore, lead to
The tilt angle for crossing adjustment inclined optical fiber grating is lost Stokes signal light wavelength nearby larger, in optical fiber
To the intensity of Stokes signal light after capable of being significantly inhibited in laser oscillator.Meanwhile near signal light wavelength, pole is lost
It is small, other higher losses will not be introduced to influence fibre laser oscillator efficiency, so that the ability under higher output power
It observes SBS, to achieve the purpose that inhibit SBS, the SBS threshold of fibre laser oscillator is improved, so as to improve optical-fiber laser
The output characteristics of oscillator.
Compared with the prior art, the advantages of the present invention are as follows:
1, inclined optical fiber grating is simple for production, and screen periods, tilt angle, modulation can be adjusted flexibly according to actual needs deeply
The parameters such as degree, to match different inhibition wave bands.
2, inclined optical fiber grating is lost small in signal light-wave strong point, has high loss in Brillouin's wave band Stokes signal light
Property.Convenient simultaneously to be prepared on different type optical fiber, stability is good, has wide range of applications.Inclined optical fiber grating can be direct
It is prepared on doped fiber, further decreases overall losses.
3, by controlling the number of the concatenated inclined optical fiber grating of welding, inhibition ratio is adjusted flexibly.
4, good buffer action can be played to Stokes signal light to rear.
Detailed description of the invention
Fig. 1 is the schematic diagram of the embodiment of the present invention 1；
Fig. 2 is the schematic diagram of the embodiment of the present invention 2；
Fig. 3 is the schematic diagram of the embodiment of the present invention 3；
Fig. 4 is the schematic diagram of the embodiment of the present invention 4；
Fig. 5 is the schematic diagram of the embodiment of the present invention 5；
Fig. 6 is the schematic diagram of the embodiment of the present invention 6；
Fig. 7 is the schematic diagram of the embodiment of the present invention 7；
Fig. 8 is the schematic diagram of the embodiment of the present invention 8；
Fig. 9 is the schematic diagram of the embodiment of the present invention 9；
Figure 10 is the schematic illustration of inclined optical fiber grating used in the present invention；
Figure 11 is the typical transmission spectrogram and partial enlarged view of inclined optical fiber grating used in the present invention；
Figure 12 is typical Stokes signal light inhibitory effect figure of the invention.
Specific embodiment
With reference to the accompanying drawing, embodiments of the present invention are described in further detail.
Fig. 1 is the structural schematic diagram of the embodiment of the present invention 1.It is forward pumping fibre laser oscillator in embodiment 1.Fig. 2
It is the structural schematic diagram of the embodiment of the present invention 2.It is backward pump fibre laser oscillator in embodiment 2.Embodiment 2 removes pumping side
Formula is different from embodiment 1 outer, and the setting of inclined optical fiber grating and embodiment 1 are consistent.Fig. 3 is the structure of the embodiment of the present invention 3
Schematic diagram.It is two directional pump fibre laser oscillator in embodiment 3.Embodiment 3 in addition to pump mode is different from embodiment 1,
The setting of inclined optical fiber grating and embodiment 1 are consistent.Fibre laser oscillator in embodiment 1,2 and 3 includes pumping LD light
Source 1, pump combiner 2, high reflective grid 3, doped fiber 4, low reflective grid 6.Embodiment 1,2 and 3 is by inclined optical fiber grating 5
It is arranged in front of the intracavitary low reflective grid 6 of fibre laser oscillator.
It is described in detail by taking embodiment 1 shown in FIG. 1 as an example below.Pumping LD light source 1 has multiple, each pumping LD light
The output tail optical fiber in source 1 is connected in each pumping arm of pump combiner 2.For common fibre laser oscillator, pumping
Source wavelength is chosen as 976nm or 915nm, and output power is in hectowatt magnitude；In actual use, the ginseng of LD light source is pumped
Number, selection wavelength, output power etc. are because practical and different, without particular/special requirement.Pumping in forward pumping fibre laser oscillator
Bundling device 2 is usually 7*1 pump combiner.It typically is 6+1*1 pump combiners for backward pump fibre laser oscillator.Pumping
The output tail optical fiber of bundling device 2 is large mode field optical fiber, is typically the LMA-GDF-20/400-M optical fiber of Nufern company.Beam is closed in pumping
High reflective grid 3, doping grating 4, inclined optical fiber grating 5 and low reflective grid 6 are sequentially connected after the output tail optical fiber of device 2.This reality
Applying inclined optical fiber grating 5 and the preparation of low reflective grid 6 in example, over the same fiber, wherein inclined optical fiber grating 5 is located at low anti-
The front of grating 6 and the two keeps a fixed spacing to optimize oscillator performance.The output tail optical fiber of pump combiner 2 and high reflective grid
Pass through the side of welding between 3, between high reflective grid 3 and doping grating 4 and between doped fiber 4 and inclined optical fiber grating 5
Formula is attached, and fusing point 7 is formed at posetionof weld.Pumping LD light source 1, high reflective grid 3, doped fiber 4, inclines at pump combiner 2
The fibre laser oscillator that oblique fiber grating 5, low reflective grid 6 and fusing point 7 are constituted.High reflective grid 3 are in fibre laser oscillator
Operating wave strong point, reflectivity are typically larger than 99%, and three dB bandwidth is usually 2-4nm, are prepared in same pump combiner output optical fibre phase
On same optical fiber.Doped fiber 4 should choose the doped fiber to match with high reflective grid 3, be typically the LMA- of Nufern company
YDF-20/400-M optical fiber.Low reflective its reflectivity of grid 6 for output is usually more than 10%, and three dB bandwidth is usually more than
1nm, central wavelength is differed with the central wavelength of high reflective grid 3 should be not more than ± 0.4nm.
It pumps LD light source 1 and pump light necessary to generating laser is provided, pump light couples supreme anti-via pump combiner 2
At grating 3.High reflective grid 3, only in signal light-wave strong point, as there is reflection at 1080nm, are pumping light wave with low reflective grid 6
Strong point does not reflect, only lossy.Pump light is injected into doped fiber 4 via high reflective grid 3.Doped fiber 4 usually adulterates
The rare earth elements such as ytterbium can absorb pump light and inspire signal light.
Since oscillator chamber self-energy density is higher, loss has large effect to its efficiency.Inclined optical fiber grating 5 with
Low reflective grid 6 due to prepare over the same fiber, therefore between there is no fusing point, with further decrease oscillation chamber loss, improve
Delivery efficiency.Optical fiber used in inclined optical fiber grating 5 need to match fibre laser oscillator.When signal light intensity in fibre laser oscillator
When degree is more than certain threshold value, SBS effect can be generated, the pump light for continuing injection at this time can be converted to Stokes light rapidly, be formed
Stronger backward Stokes light, as shown in hollow arrow in Fig. 1,2,3.It include two kinds of light of signal light and backward Stokes light
When laser passes through inclined optical fiber grating 5, since inclined optical fiber grating optical fiber 5 is small in the loss of signal light-wave strong point, believe in Stokes
Number light wave strong point has high lossy, and the Stokes signal in laser is optically coupled to fibre cladding and loses, in laser
Stokes signal light intensity can generate decaying, to inhibit the generation of excited Brillouin process, so that amplifying in higher level-one
Excited Brillouin process could be generated under power condition, to have the function that improve SBS threshold.
Inclined optical fiber grating 5 is due to its unique Mode Coupling characteristic, the interior Stokes signal light meeting transmitted of fiber core
It intercouples with the mode in covering, it is caused to be coupled to fibre cladding and is scattered and lost, so that inclined optical fiber grating 5 is in Stokes
The signal light-wave strong point loss spectra narrow there are a very bandwidth, the Stokes signal light intensity in laser can generate decaying, as shown in figure 1
Shown in filled arrows.In this way, decayed by introducing high loss at Stokes wavelength to Stokes signal strength, thus
Inhibit the generation of excited Brillouin process.So that excited Brillouin mistake could be generated under the conditions of higher level-one amplifying power
Journey, to have the function that improve SBS threshold.The addition of inclined optical fiber grating 5 has inhibiting effect to Stokes light to rear, from
And risk is reduced, and play buffer action.In order to further enhance fibre laser oscillator SBS inhibitory effect, multiple parameters phase
Same inclined optical fiber grating accesses in fibre laser oscillator after being together in series by way of welding, inhibits than suitable
Inhibit the superposition of ratio in multiple inclined optical fiber gratings.By the control to inclined optical fiber grating number, can accomplish to inhibition ratio
Be adjusted flexibly.
Fig. 4 is the structural schematic diagram of the embodiment of the present invention 4.It is forward pumping fibre laser oscillator in embodiment 4.Fig. 5
It is the structural schematic diagram of the embodiment of the present invention 6.It is backward pump fibre laser oscillator in embodiment 7.Except pump mode and reality
It is different outer to apply example 4, the setting of inclined optical fiber grating and embodiment 4 are consistent.Fig. 6 is the structural schematic diagram of the embodiment of the present invention 6.
It is two directional pump fibre laser oscillator in embodiment 6.In addition to pump mode is different from embodiment 4, inclined optical fiber grating
Setting is consistent with embodiment 4.Pump LD light source 1, pump combiner 2, high reflective grid 3, inclined optical fiber grating 5, doped fiber 4,
The fibre laser oscillator that low reflective grid 6 and fusing point 7 are constituted.Embodiment 4,5 and 6 is that the setting of inclined optical fiber grating 5 exists
After the intracavitary reflective grid 3 of height of fibre laser oscillator.At high reflective grid 3 compared to low reflective grid 6 at, have higher energy
Density inhibits initial Stokes signal light after inclined optical fiber grating 5 is placed in high reflective grid 3, is excited cloth to whole
In deep process have more good inhibitory effect.
When signal light intensity is more than certain threshold value in fibre laser oscillator, SBS effect can be generated, continues to inject at this time
Pump light can be converted to Stokes light rapidly, stronger backward Stokes light is formed, as shown in hollow arrow in Fig. 4,5,6.
Include the laser of signal light and backward two kinds of light of Stokes light by inclined optical fiber grating 5 when, due to inclined optical fiber grating light
Fibre 5 is small in the loss of signal light-wave strong point, has high lossy in Stokes signal light-wave strong point, the Stokes signal light in laser
It is coupled to fibre cladding and loses, the Stokes signal light intensity in laser can generate decaying, to inhibit excited Brillouin
The generation of process, so that excited Brillouin process could be generated under the conditions of higher level-one amplifying power, to reach raising
The effect of SBS threshold.
Fig. 7 is the structural schematic diagram of the embodiment of the present invention 7.It is forward pumping fibre laser oscillator in embodiment 7.Fig. 8
It is the structural schematic diagram of the embodiment of the present invention 8.It is backward pump fibre laser oscillator in embodiment 8.Except pump mode and reality
It is different outer to apply example 7, the setting of inclined optical fiber grating and embodiment 7 are consistent.Fig. 9 is the structural schematic diagram of the embodiment of the present invention 9.
It is two directional pump fibre laser oscillator in embodiment 9.In addition to pump mode is different from embodiment 7, inclined optical fiber grating
Setting is consistent with embodiment 7.Pump LD light source 1, pump combiner 2, high reflective grid 3, doped fiber 4, inclined optical fiber grating 5,
The fibre laser oscillator that low reflective grid 6 and fusing point 7 are constituted.Embodiment 7,8 and 9 is directly to carve inclined optical fiber grating 5
It writes on the intracavitary doped fiber 4 of fibre laser oscillator.Since oscillator chamber self-energy density is higher, loss has its efficiency
Large effect.During actually building oscillator, fiber grating has been encapsulated, and inconvenience carries out fiber grating inscription, can be incited somebody to action
Inclined optical fiber grating 5 is directly scribed on the intracavitary doped fiber 4 of fibre laser oscillator, to further decrease the damage of oscillation chamber
Consumption improves delivery efficiency.
Figure 10 is the schematic illustration of inclined optical fiber grating used in the present invention.It is similar with common Bragg fiber grating,
Inclined optical fiber grating is also that periodic refractive index modulation is presented along optical fiber axial direction in fibre core, be a difference in that grating planar with
Optical fiber is tangentially in certain inclination angle.Due to the presence of tilt angle, in addition to there is the preceding coupling to the fibre core intermode with reverse transfers
Outside closing, there is also the cladding modes or radiation mode of the core mode of fl transmission and reverse transfers (assuming that the feelings of cladding diameter infinity
Under condition) between coupling.It will appear many discrete resonance peaks in the transmitted spectrum intermediate waves region of inclined optical fiber grating, here it is
The coupling phenomenon of core mode and covering intermode.
Figure 11 is that the typical transmission spectrum for the inclined optical fiber grating that the present invention uses and partial enlarged view, wave band are selected as inhibiting
The backward Stokes signal light wavelength 1064.06nm of 1064nm laser.In actual use, the central wavelength of inclined optical fiber grating is needed
Actual needs is matched by design.Its fiber type should flexible choice according to actual needs.
Figure 12 is typical Stokes signal light inhibitory effect figure of the invention.When accessing inclined optical fiber grating, higher
Pump power under, just it is observed that apparent Stokes light echo, SBS threshold, which has, to be obviously improved；With pump power into
One step is promoted, and when the power of Stokes light echo is not compared to grating is accessed, is decreased obviously, and with inclined optical fiber grating
Welding serial number purpose increases, and Stokes light echo power can further decline.
The foregoing is merely a preferred embodiment of the present invention, are not intended to restrict the invention, for this field
For technical staff, the invention may be variously modified and varied.All within the spirits and principles of the present invention, made any
Modification, equivalent replacement, improvement etc., should all be included in the protection scope of the present invention.
Claims (10)
1. a kind of method that fibre laser oscillator inhibits stimulated Brillouin scattering, which is characterized in that by the way that optical fiber light will be tilted
Grid incoming fiber optic laser oscillator is intracavitary, using inclined optical fiber grating Brillouin's wave band high lossy, to injection oblique light
Laser in fine grating is filtered, to inhibit stimulated Brillouin scattering.
2. the method that fibre laser oscillator according to claim 1 inhibits stimulated Brillouin scattering, which is characterized in that light
Fine laser oscillator is that forward pumping fibre laser oscillator, backward pump fibre laser oscillator or two directional pump optical fiber swash
Optical generator.
3. the method that fibre laser oscillator according to claim 2 inhibits stimulated Brillouin scattering, which is characterized in that light
Fine laser oscillator includes pumping LD light source, pump combiner, high reflective grid, doped fiber, low reflective grid.
4. the method that fibre laser oscillator according to claim 3 inhibits stimulated Brillouin scattering, which is characterized in that will
Before the intracavitary low reflective grid of fibre laser oscillator are arranged in inclined optical fiber grating.
5. the method that fibre laser oscillator according to claim 4 inhibits stimulated Brillouin scattering, which is characterized in that institute
Inclined optical fiber grating is stated to be independently arranged, inclined optical fiber grating preparation on an individual optical fiber its both ends by way of welding
It is connect respectively with the input terminal of the output end of doped fiber and low reflective grid；
Alternatively, the inclined optical fiber grating and low reflective grid preparation are over the same fiber, wherein inclined optical fiber grating is located at low
The front of reflective grid and the two keeps a fixed spacing to optimize oscillator performance.
6. the method that fibre laser oscillator according to claim 3 inhibits stimulated Brillouin scattering, which is characterized in that will
After the intracavitary reflective grid of height of fibre laser oscillator are arranged in inclined optical fiber grating.
7. the method that fibre laser oscillator according to claim 6 inhibits stimulated Brillouin scattering, which is characterized in that institute
Inclined optical fiber grating is stated to be independently arranged, inclined optical fiber grating preparation on an individual optical fiber its both ends by way of welding
It is connect respectively with the input terminal of the output end of high reflective grid and doped fiber；
Alternatively, the inclined optical fiber grating and high reflective grid preparation are over the same fiber, wherein inclined optical fiber grating is located at height
The rear of reflective grid and the two keeps a fixed spacing to optimize oscillator performance.
8. the method that fibre laser oscillator according to claim 3 inhibits stimulated Brillouin scattering, which is characterized in that will
Inclined optical fiber grating is directly scribed on the intracavitary doped fiber of fibre laser oscillator.
9. inhibiting stimulated Brillouin scattering to fibre laser oscillator described in any claim in 8 according to claim 1
Method, which is characterized in that the identical inclined optical fiber grating of multiple parameters is one another in series by way of welding and is followed by together
Enter the intracavitary corresponding position of fibre laser oscillator, by way of increasing inclined optical fiber grating number, to further increase suppression
Ratio processed.
10. the method that fibre laser oscillator according to claim 3 inhibits stimulated Brillouin scattering, which is characterized in that
High anti-grating operation is at laser works wavelength, and the reflectivity of high reflective grid is greater than 99%, and three dB bandwidth is usually 2-4nm, system
It is standby on the identical optical fiber of same pump combiner its output optical fibre；Doped fiber should choose the doping light to match with high reflective grid
It is fine；The reflectivity of low reflective grid is not more than 10%, and three dB bandwidth is usually more than 1nm；Low its central wavelength of reflective grid and height are reflective
The central wavelength of grid is identical or its difference range with the central wavelength of high reflective grid is between ± 0.4nm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811270199.4A CN109193336B (en) | 2018-10-29 | 2018-10-29 | Method for suppressing stimulated Brillouin scattering by fiber laser oscillator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811270199.4A CN109193336B (en) | 2018-10-29 | 2018-10-29 | Method for suppressing stimulated Brillouin scattering by fiber laser oscillator |
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| CN112332203A (en) * | 2020-09-17 | 2021-02-05 | 中国电子科技集团公司第十一研究所 | Optical fiber amplifier |
| CN115498486A (en) * | 2022-11-18 | 2022-12-20 | 中国航天三江集团有限公司 | Method and system for improving SBS (styrene-butadiene-styrene) threshold of high-power laser by utilizing magnetostrictive effect |
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| CN112332203A (en) * | 2020-09-17 | 2021-02-05 | 中国电子科技集团公司第十一研究所 | Optical fiber amplifier |
| CN115498486A (en) * | 2022-11-18 | 2022-12-20 | 中国航天三江集团有限公司 | Method and system for improving SBS (styrene-butadiene-styrene) threshold of high-power laser by utilizing magnetostrictive effect |
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