CN116482800B - Special optical fiber, laser and laser processing system - Google Patents
Special optical fiber, laser and laser processing system Download PDFInfo
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- CN116482800B CN116482800B CN202310728832.4A CN202310728832A CN116482800B CN 116482800 B CN116482800 B CN 116482800B CN 202310728832 A CN202310728832 A CN 202310728832A CN 116482800 B CN116482800 B CN 116482800B
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- 239000013307 optical fiber Substances 0.000 title claims abstract description 96
- 238000012545 processing Methods 0.000 title claims abstract description 18
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 115
- 238000012216 screening Methods 0.000 claims abstract description 78
- 238000001228 spectrum Methods 0.000 claims abstract description 78
- 239000002131 composite material Substances 0.000 claims abstract description 63
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 57
- 239000000835 fiber Substances 0.000 claims abstract description 54
- 238000005253 cladding Methods 0.000 claims abstract description 33
- 235000012239 silicon dioxide Nutrition 0.000 claims abstract description 27
- 238000005086 pumping Methods 0.000 claims description 38
- 238000003466 welding Methods 0.000 claims description 18
- -1 boron ions Chemical class 0.000 claims description 12
- 230000003595 spectral effect Effects 0.000 claims description 12
- 229910052796 boron Inorganic materials 0.000 claims description 4
- 229910052732 germanium Inorganic materials 0.000 claims description 3
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 3
- 238000003384 imaging method Methods 0.000 claims description 2
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 claims 1
- 230000003287 optical effect Effects 0.000 abstract description 22
- 101100456571 Mus musculus Med12 gene Proteins 0.000 abstract description 7
- 230000005540 biological transmission Effects 0.000 abstract description 6
- 238000010438 heat treatment Methods 0.000 abstract description 6
- 239000010410 layer Substances 0.000 description 160
- 239000004065 semiconductor Substances 0.000 description 11
- 238000010586 diagram Methods 0.000 description 7
- 238000009826 distribution Methods 0.000 description 7
- 150000002500 ions Chemical class 0.000 description 6
- 238000000034 method Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 230000009977 dual effect Effects 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 229910052731 fluorine Inorganic materials 0.000 description 3
- 239000011737 fluorine Substances 0.000 description 3
- 238000013461 design Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 230000003321 amplification Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 description 1
- 238000004372 laser cladding Methods 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 238000009774 resonance method Methods 0.000 description 1
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical compound [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
-
- 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
- H01S3/06708—Constructional details of the fibre, e.g. compositions, cross-section, shape or tapering
- H01S3/06729—Peculiar transverse fibre profile
- H01S3/06733—Fibre having more than one cladding
-
- 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
- H01S3/06791—Fibre ring lasers
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- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Optics & Photonics (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- General Physics & Mathematics (AREA)
- Lasers (AREA)
Abstract
The invention relates to the technical field of optical elements and provides a special optical fiber, a laser and a laser processing system, wherein the special optical fiber comprises a fiber core, a first silicon dioxide layer, an angular spectrum screening layer, a waveguide layer and other multi-cladding structures, so that the special optical fiber can realize a MOPA structure, can meet the requirement of higher-power composite output, can further amplify the light spot energy of the central area of an output composite light spot on the basis of signal light power, can improve the power of the central area of the composite light spot, and reduces the requirement on laser output by a resonant cavity. Moreover, as the annular area can realize high-brightness light spot output, the annular divergence angle of the whole optical path can be prevented from further increasing, the heating risk of the space optical device in the outer ring optical transmission process can be further avoided, the damage risk of the space optical path device is reduced, the combination of the MOPA structure and the composite light spot output is realized, and the complexity of the optical path is also reduced.
Description
Technical Field
The invention relates to the technical field of optical components, in particular to a special optical fiber, a laser and a laser processing system.
Background
The laser composite welding technology provides a feasible solving direction for high-quality precision welding. The conventional dual-path composite laser welding technology requires either a beam splitter to generate dual beams or two separate lasers to generate dual beams, and then utilizes a composite welding head of a dual main path to combine the two laser beams.
And the method is simpler, and can realize dual-wavelength composite light spots of central and annular output based on the beam combiner and the optical fiber design, so that high-quality processing can be realized. The central area is used as a light source by signal light, and the annular area is used as a light source by semiconductor pump light. The proposal shows the distribution of the compound light spots with the center added with the ring shape when observed from the angle of the transverse mode; viewed from the longitudinal mode, a dual wavelength output is presented. And on the spot energy distribution, the splashing of welding can be effectively restrained. From the wavelength utilization perspective, the pump light is directly utilized, the process of energy conversion of laser is omitted, the reduction of energy efficiency caused by quantum loss is avoided, and the pump light has smaller heating value under the same power. However, there are some aspects to be improved on such a scheme:
(1) In the conventional scheme, a light source in a central region outputs laser light by a direct resonance method. Therefore, in order to further increase the power of the central region of the composite spot, it is required to generate laser output by the resonant cavity while satisfying high brightness and high power, which is difficult.
(2) In the existing dual-wavelength composite light spot output scheme, the light source of the annular region is a semiconductor laser. Because the brightness of the semiconductor laser is often lower, the annular divergence angle of the optical path of the whole laser can be further increased. This means that there is a risk of heating the space optics during the transmission of the external ring light after the laser output.
Disclosure of Invention
The invention provides a special optical fiber, a laser and a laser processing system, which are used for solving the defects in the prior art.
The invention provides a special optical fiber, comprising: the fiber core comprises a first silicon dioxide layer, an angular spectrum screening layer and a waveguide layer which are sequentially arranged on the outer side of the fiber core in a surrounding manner;
the fiber core is used for accessing signal light;
the waveguide layer is used for accessing pump light;
the angular spectrum screening layer is used for binding a first pumping component which is not lower than a brightness threshold value in the pumping light and allowing a second pumping component which is lower than the brightness threshold value to pass through the angular spectrum screening layer and the first silicon dioxide layer to the fiber core so as to amplify the signal light in the fiber core.
According to the special optical fiber provided by the invention, the waveguide layer comprises a second silicon dioxide layer and an outer cladding layer, wherein the second silicon dioxide layer is arranged on the outer side of the angular spectrum screening layer in a surrounding manner, and the outer cladding layer is arranged on the outer side of the second silicon dioxide layer in a surrounding manner;
the second silica layer has a refractive index higher than the refractive index of the outer cladding layer.
According to the special optical fiber provided by the invention, the fiber core is further used for outputting amplified target signal light, the angular spectrum screening layer is further used for outputting the first pumping component, and the target signal light and the pumping component form a composite light spot;
the power of the composite spot is tuned based on the power of the pump light and the power of the signal light.
According to the special optical fiber provided by the invention, the composite light spot comprises a central area and an annular area;
the power of the central region is determined based on the power of the signal light, the power of the pump light, the duty ratio of the second pump component, and the luminous efficiency;
the power of the annular region is determined based on the power of the pump light and the duty cycle of the first pump component.
According to the special optical fiber provided by the invention, the duty ratio of the first pumping component is determined based on the energy spectrum density of the pumping light and the numerical aperture of the angular spectrum screening layer;
the duty cycle of the second pump component is determined based on the duty cycle of the first pump component or based on the energy spectral density of the pump light and the numerical aperture of the angular spectral screening layer.
According to the special optical fiber provided by the invention, the power of the central area is determined based on the following formula:
；
the power of the annular region is determined based on the following formula:
；
wherein ,for the power of the central region, +.>For the power of the annular region, +.>For the energy spectral density of the pump light,NAscreening the angular spectrum for the numerical aperture of the layer, < >>For luminous efficiency, +.>For the power of the pump light,for the power of the signal light, +.>For the duty cycle of the second pump component, < > and>is the duty cycle of the first pump component.
According to the special optical fiber provided by the invention, the outer cladding is doped with fluorine ions or boron ions.
According to the special optical fiber provided by the invention, rare earth ions are doped in the fiber core.
According to the special optical fiber provided by the invention, the refractive index of the angular spectrum screening layer is larger than that of the first silicon dioxide layer.
According to the special optical fiber provided by the invention, the angular spectrum screening layer is doped with germanium ions.
The invention also provides a laser, which comprises a pumping light source, a resonant cavity, an output element and the special optical fiber;
the pump light source is used for providing the pump light for the special optical fiber;
the resonant cavity is used for providing the signal light for the special optical fiber;
the output element is used for transmitting the composite laser output by the special optical fiber.
According to the laser provided by the invention, the output element is a passive optical fiber;
the passive optical fiber has the same refractive index profile as the specialty optical fiber.
The laser provided by the invention further comprises a beam combining element, wherein the input end of the beam combining element is respectively connected with the output end of the pumping light source and the output end of the resonant cavity;
the beam combining element is used for combining the pump light and the signal light, and inputting a beam combining result into the special optical fiber so that the signal light is incident to the fiber core of the special optical fiber, and the pump light is incident to the waveguide layer or the waveguide layer and the angular spectrum screening layer of the special optical fiber.
The invention also provides a laser processing system which comprises a welding head and the laser, wherein the welding head is connected with an output element in the laser and is used for imaging a composite light spot of composite laser output by the laser to a workpiece to be processed for processing.
Compared with the prior art, the invention has the following beneficial effects:
the special optical fiber, the laser and the laser processing system provided by the invention comprise a fiber core, a first silicon dioxide layer, an angular spectrum screening layer, a waveguide layer and other multi-cladding structures, so that the special optical fiber can realize a MOPA structure, can meet the composite output of higher power, can further amplify the light spot energy of the central area of the output composite light spot on the basis of the signal light power, can improve the power of the central area of the composite light spot, and can reduce the requirement on the laser output by a resonant cavity. Moreover, as the annular area can realize high-brightness light spot output, the annular divergence angle of the whole optical path can be prevented from further increasing, the heating risk of the space optical device in the outer ring optical transmission process can be further avoided, the damage risk of the space optical path device is reduced, the combination of the MOPA structure and the composite light spot output is realized, and the complexity of the optical path is also reduced.
Drawings
In order to more clearly illustrate the invention or the technical solutions of the prior art, the following description will briefly explain the drawings used in the embodiments or the description of the prior art, and it is obvious to those skilled in the art that other drawings can be obtained according to these drawings without inventive effort.
FIG. 1 is a schematic diagram of a special optical fiber according to the present invention;
FIG. 2 is a second schematic diagram of a special optical fiber according to the present invention;
FIG. 3 is a schematic view of refractive index distribution of each layer in a special optical fiber provided by the invention;
FIG. 4 is a schematic diagram of input and output of a special fiber according to the present invention;
FIG. 5 is a schematic diagram of a laser according to the present invention;
FIG. 6 is a second schematic diagram of a laser according to the present invention;
fig. 7 is a schematic structural diagram of a laser processing system provided by the present invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is apparent that the described embodiments are some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Because the light source of the central area of the composite light spot obtained in the prior art outputs laser in a direct resonance mode, when the power of the central area of the composite light spot is further improved, the resonant cavity is required to generate laser output which simultaneously meets high brightness and high power, and the difficulty is high. The light source of the annular region of the composite light spot is a semiconductor laser. Due to the low brightness of the semiconductor laser, the output external ring light risks heating the spatial optics during transmission. Based on the above, in order to solve the problems existing in the special optical fiber in the prior art, the embodiment of the invention provides the special optical fiber.
Fig. 1 is a schematic cross-sectional structure of a special optical fiber according to an embodiment of the present invention, and as shown in fig. 1, the special optical fiber 10 includes: the core 1 and the first Silica (SiO) disposed around the outside of the core 1 in this order 2 ) Layer 2, angular spectrum screening layer 3 and waveguide layer 4.
The fiber core 1 is used for accessing signal light;
the waveguide layer 4 is used for accessing pump light;
the angular spectrum screening layer 3 is used for confining a first pump component which is not lower than a brightness threshold value in the pump light, and allowing a second pump component which is lower than the brightness threshold value to pass through the angular spectrum screening layer 3 and the first silica layer 2 to the fiber core 1, so as to amplify the signal light in the fiber core 1.
Specifically, the special optical fiber 10 sequentially comprises a fiber core 1, a first silicon dioxide layer 2, an angular spectrum screening layer 3 and a waveguide layer 4 from inside to outside, wherein the first silicon dioxide layer 2 is arranged around the fiber core 1, the angular spectrum screening layer 3 is arranged around the first silicon dioxide layer 2, and the waveguide layer 4 is arranged around the angular spectrum screening layer 3. The first silica layer 2, the angular spectrum screening layer 3 and the waveguide layer 4 may be respectively used as one cladding of the special optical fiber 10, and the special optical fiber 10 may be regarded as a three-cladding structure.
It should be understood that the three-clad structure is a general description herein, and the cladding structure of the special optical fiber 10 may be further subdivided according to the specific structure of the waveguide layer 4 when the waveguide layer 4 is regarded as a whole, for example, if the waveguide layer 4 is a single-layer structure, the special optical fiber 10 is actually a three-clad structure; if the waveguide layer 4 has a double-layer structure, the special optical fiber 10 has a four-clad structure. Generally, if the waveguide layer 4 has an n (n.gtoreq.1) layer structure, the special optical fiber 10 has an (n+2) cladding structure. The three-cladding structure and the (n+2) cladding structure are all different applications under the same principle.
The fiber core 1 can be used for receiving signal light, and the signal light can be provided by a resonant cavity of the laser, namely, the signal light can be obtained through the optical amplification effect of a gain medium in the resonant cavity. Typically, the refractive index of the core 1 is highest, i.e. the refractive index of the core 1 is higher than the refractive index of the first silica layer 2, and the signal light may be confined within the core 1 due to the presence of the first silica layer 2. The core 1 is also used for amplifying the signal light due to the presence of the angular spectrum screening layer 3 and may be transmitted based on the principle of total reflection.
Also, since the first silica layer 2 is located between the core 1 and the angular spectrum screening layer 3, it can be used to isolate the core 1 from the angular spectrum screening layer 3.
The central wavelength of the signal light may be selected according to the need, and the range of the central wavelength may be 850nm to 2140nm, for example 980nm, 1310nm, 1350nm, etc., which is not particularly limited herein. In the embodiment of the invention, the wavelength of the signal light may be preferably 1030nm to 2140nm, for example 1080nm.
The waveguide layer 4 may be used to switch in pump light that may be provided as laser light output by the semiconductor laser, i.e. as the pump light. The pump light can be transmitted within the waveguide layer 4 based on the principle of total reflection. The central wavelength of the pump light may be selected as needed, and the signal light in the special optical fiber may be amplified, and the central wavelength may be in the range of 900nm to 1550nm, preferably 900nm to 1000nm, 1480nm to 1550nm, for example 915nm, 976nm, 980nm, 1480nm, 1060nm, or the like, and the present invention is not particularly limited.
Here, the signal light and the pump light may be first combined by the beam combining element, and the result of the beam combination is coupled to the special optical fiber 10, so that the signal light is connected to the core 1 of the special optical fiber 10, and the pump light is connected to the waveguide layer 4 of the special optical fiber 10.
The angular spectrum screening layer 3 is located between the first silica layer 2 and the waveguide layer 4, and has a function of screening a low-luminance component and a high-luminance component in the pump light. In detail, when the pump light is transmitted in the waveguide layer 4, a first pump component of the pump light not lower than the brightness threshold is bound by the angular spectrum screening layer 3, and the first pump component is output after being continuously transmitted in the angular spectrum screening layer 3, and a second pump component of the pump light lower than the brightness threshold passes through the angular spectrum screening layer 3 and continuously passes through the first silica layer 2 to reach the fiber core 1, so that the signal light in the fiber core 1 is amplified.
It will be appreciated that the brightness threshold, which may be characterized by the Numerical Aperture (NA) of the angular spectrum screening layer 3, may be set as desired. The numerical aperture may represent the ability of the end face of the angular spectrum screening layer 3 to receive light, and its value is the same as the ability of the optical fiber to receive light and the effect on the modal dispersion.
Here, the signal light generated by the resonant cavity is input to the fiber core 1, and is input to the waveguide layer 4 and amplified by the second pump component screened by the angular spectrum screening layer 3, so that a main oscillation amplifying (MOPA) structure can be formed, which is favorable for obtaining higher-power central light spot energy. Whereas the first pump component at the edge can obtain an edge spot of higher brightness because it is not lower than the brightness threshold.
The specialty fiber 10 may have a silica material as a substrate and form the core 1 and the angular spectrum screening layer 3, respectively, by doping different ions in corresponding regions of the substrate. The first silica layer 2 can avoid the functional failure caused by the mixing of the doped ions of the fiber core 1 and the angular spectrum screening layer 3.
The special optical fiber provided by the embodiment of the invention comprises a fiber core, a first silicon dioxide layer, an angular spectrum screening layer, a waveguide layer and other multi-cladding structures, so that the special optical fiber can realize a MOPA structure, can meet the composite output of higher power, can further amplify the light spot energy of the central area of the output composite light spot on the basis of the signal light power, can improve the power of the central area of the composite light spot, and reduces the requirement on laser output by a resonant cavity. Moreover, as the annular area can realize high-brightness light spot output, the annular divergence angle of the whole optical path can be prevented from further increasing, the heating risk of the space optical device in the outer ring optical transmission process can be further avoided, the damage risk of the space optical path device is reduced, the combination of the MOPA structure and the composite light spot output is realized, and the complexity of the optical path is also reduced.
On the basis of the embodiment, the waveguide layer comprises a second silicon dioxide layer and an outer cladding layer, wherein the second silicon dioxide layer is arranged on the outer side of the angular spectrum screening layer in a surrounding mode, and the outer cladding layer is arranged on the outer side of the second silicon dioxide layer in a surrounding mode;
the second silica layer has a refractive index higher than the refractive index of the outer cladding layer.
Specifically, as shown in fig. 2, the waveguide layer 4 includes a second silicon oxide (SiO 2 ) A layer 41 and an outer cladding 42, the second silica layer 41 being arranged around the outside of the angular spectrum screening layer 3, the outer cladding being arranged around the outside of the second silica layer 41.
Here, the outer cladding 42 may be a low refractive index layer, i.e., the refractive index of the outer cladding 42 is lower than that of the second silica layer 41, so that the pump light can be inputted into the second silica layer 41 and transmitted by being bound in the second silica layer 41 due to the presence of the outer cladding 42. The overclad layer 42 may be formed by doping a silica material with functional ions, or may be made of a low refractive index material such as a resin layer. The type of the functional ion may be selected as required to ensure that the refractive index of the outer cladding layer 42 is lower than that of the second silica layer 41, which is not particularly limited herein.
In the embodiment of the invention, the second silicon dioxide layer and the outer cladding layer are included in the waveguide layer, so that the pump light can be transmitted in the second silicon dioxide layer, and the aim of dividing the pump light into the first pump component and the second pump component through the angular spectrum screening layer can be fulfilled.
On the basis of the above embodiment, the fiber core is further configured to output the amplified target signal light, and the angular spectrum screening layer is further configured to output the first pump component, where the target signal light and the pump component form a composite light spot;
the power of the composite spot is tuned based on the power of the pump light and the power of the signal light.
Specifically, the special optical fiber has a fiber core 1 capable of outputting a target signal light obtained by amplifying a signal light by a second pumping component, an angular spectrum screening layer 3 capable of outputting a first pumping component bound by the fiber core 1, and the angular spectrum screening layer 3 capable of jointly outputting a composite light spot. The composite spot may include a central region formed by the target signal light and an outer annular region formed by the first pump component.
Further, the power of the composite light spot can be tuned by the power of the pump light and the power of the signal light, i.e. by changing the power of the pump light and the power of the signal light, a change of the power of the composite light spot can be achieved.
Here, the user can pre-calibrate the cooperative variation of the power of the pump light and the power of the signal light according to the light spot power requirement, so that a composite light spot meeting the user requirement can be obtained.
In the embodiment of the invention, the power of the output composite light spot can be tuned by adjusting the power of the input special optical fiber, namely the pump light and the signal light, so that the subsequent application of the output special optical fiber in different scenes is facilitated.
On the basis of the embodiment, the composite light spot comprises a central area and an annular area;
the power of the central region is determined based on the power of the signal light, the power of the pump light, the duty ratio of the second pump component, and the luminous efficiency;
the power of the annular region is determined based on the power of the pump light and the duty cycle of the first pump component.
Specifically, the duty ratio of the first pumping component refers to the ratio of the first pumping component to the pump light, the duty ratio of the second pumping component refers to the ratio of the second pumping component to the pump light, and the luminous efficiency refers to the utilization ratio of the second pumping component.
When determining the power of the central area of the composite light spot, the contribution power of the second pumping component to the signal light can be determined by multiplying the power of the pumping light, the duty ratio of the second pumping component and the luminous efficiency, and then the power of the signal light and the contribution power of the second pumping component to the signal light are added to obtain the result of the addition, namely the power of the central area of the composite light spot.
Here, the power of the central region can be calculated by the following formula:
；
wherein ,for the power of the central region, +.>For luminous efficiency, +.>For the power of the pump light, +.>For the second pump component, +.>Is the power of the signal light.
In determining the power of the annular region, the power of the pump light and the duty cycle of the first pump component may be directly used for determination, for example, the product of the power of the pump light and the duty cycle of the first pump component may be used as the power of the annular region.
Here, the power of the annular region can be calculated by the following formula:
；
wherein ,power for annular region, +.>Is the duty cycle of the first pump component.
In the embodiment of the invention, the power of the central area and the power of the annular area can be respectively determined by means of the power of the signal light and the power of the pump light, so that theoretical basis can be provided for subsequent power determination and application of the composite light spot.
On the basis of the above embodiment, the duty ratio of the first pump component is determined based on the energy spectral density of the pump light and the numerical aperture of the angular spectrum screening layer;
the duty cycle of the second pump component is determined based on the duty cycle of the first pump component or based on the energy spectral density of the pump light and the numerical aperture of the angular spectral screening layer.
Specifically, the duty cycle of the first pump component can be calculated by the following formula:
；
wherein ,for the energy spectral density of the pump light,NAnumerical aperture of the layer is selected for angular spectrum, +.>Half the aperture angle of the angular spectrum screening layer.
The duty cycle of the second pump component may be calculated based on either of two formulas:
；
；
in the embodiment of the invention, the brightness threshold value can be adjusted by adjusting the numerical aperture of the angular spectrum screening layer, so that the duty ratio of the first pumping component and the second pumping component can be adjusted, and the tuning of the power distribution of the output composite light spot can be realized. And the duty ratio of the first pumping component is determined, so that the first pumping component can be rapidly determined, the duty ratio of the second pumping component can be determined through the energy spectrum density of the pumping light and the numerical aperture of the angular spectrum screening layer, and the duty ratio of the first pumping component and the duty ratio of the second pumping component can be verified to ensure the correctness of the two.
On the basis of the above embodiment, the power of the central region is determined based on the following formula:
；
the power of the annular region is determined based on the following formula:
；
wherein ,for the power of the central region, +.>Power for annular region, +.>For the energy spectral density of the pump light,NAnumerical aperture of the layer is selected for angular spectrum, +.>For luminous efficiency, +.>For the power of the pump light, +.>For the power of the signal light, +.>For the second pump component, +.>Is the duty cycle of the first pump component.
On the basis of the above embodiment, the outer cladding is doped with fluorine ions or boron ions, i.e. the functional ions may be fluorine ions or boron ions, so as to ensure that the refractive index of the outer cladding is smaller than that of the second silicon dioxide layer and also smaller than that of the first silicon dioxide layer.
On the basis of the above embodiment, the core is doped with rare earth ions, which may include Yb, er, tm, ho plasma, where Yb may be preferred.
On the basis of the embodiment, the refractive index of the angular spectrum screening layer is larger than that of the first silicon dioxide layer, so that the first pumping component can be smoothly transmitted and output in the angular spectrum screening layer.
It is understood that the refractive index of the core 1 and the refractive index of the angular spectrum screening layer 3 are independent from each other, i.e. the refractive index of the core 1 is not necessarily greater than the refractive index of the angular spectrum screening layer 3, and the refractive index of the core 1 may be greater than the refractive index of the angular spectrum screening layer 3 or less than the refractive index of the angular spectrum screening layer 3, which is not particularly limited herein.
On the basis of the above embodiment, the angular spectrum screening layer 3 may be doped with germanium (Ge) ions, so that it is possible to ensure that the refractive index of the angular spectrum screening layer 3 is greater than that of the first silicon dioxide layer 2.
FIG. 3 is a schematic view of the refractive index distribution of each layer in the specialty fiber shown in FIG. 2. The refractive index of the fiber core 1 is larger than that of the first silica layer 2, the refractive index of the first silica layer 2 is smaller than that of the angular spectrum screening layer 3, the materials of the first silica layer 2 and the second silica layer 41 are the same, the refractive index of the first silica layer 2 and the refractive index of the second silica layer 41 are equal, the refractive index of the outer cladding 42 is smaller than that of the second silica layer 41, the second silica layer 41 and the outer cladding 42 form a waveguide layer 4 for transmitting pump light, the pump light can be subjected to angular spectrum screening of the angular spectrum screening layer 3 under the design effect of the numerical aperture of the angular spectrum screening layer 3, so that a high-brightness first pump component is restrained in the angular spectrum screening layer 3 for transmission and output, and a low-brightness second pump component is allowed to pass through the angular spectrum screening layer 3 and enter the fiber core 1 and is restrained by the fiber core 1, so that the low-brightness second pump component can amplify signal light transmitted in the fiber core 1.
Specifically, the special optical fiber 10 outputs a composite light spot including a central area and an annular area, wherein pump light is input to the second silica layer 41 and is transmitted in the waveguide layer 4 formed by the second silica layer 41 and the outer cladding layer 42, and is subjected to angular spectrum screening by the angular spectrum screening layer 3, wherein a high-brightness first pump component not lower than a brightness threshold can be transmitted in space with a smaller divergence angle, and a low-brightness second pump component lower than the brightness threshold can be transmitted in space with a larger divergence angle, and the angular spectrum screening layer 3 can bind the high-brightness second pump component, so that a high-brightness light spot in the annular area is output, high-brightness output of the annular light spot is realized, the requirement on the light source angle of the pump light is reduced, and the high-brightness outer annular light spot is favorable for reducing the damage risk of a space optical path device due to the smaller divergence angle; the divergence angle of the second pump component with low brightness is larger and cannot be bound by the angular spectrum screening layer 3, and the second pump component can pass through the angular spectrum screening layer 3 and enter the fiber core 1 and be bound in the fiber core 1, and is further amplified by signal optical coupling, so that the power of the light spot output from the center area of the fiber core 10 is improved, namely, the light spot energy of the center with higher power is favorably obtained.
Fig. 4 is a schematic diagram of input and output of the special fiber shown in fig. 2. In fig. 4, the open thick arrow indicates the pump light, the open thin arrow indicates the first pump component, the solid thin arrow indicates the signal light, and the solid thick arrow indicates the target signal light.
As shown in fig. 5, on the basis of the above embodiments, there is further provided a laser 20 according to an embodiment of the present invention, including a pump light source 51, a resonant cavity 52, an output element 53, and the special optical fiber 10 provided in each of the above embodiments;
the pump light source 51 is used for providing pump light for the special optical fiber 10;
the resonant cavity 52 is used for providing signal light for the special optical fiber 10;
the output element 53 is used for transmitting the composite laser light output from the special optical fiber 10.
Specifically, in the embodiment of the present invention, the laser 20 may be a laser with an all-fiber structure, that is, devices inside the laser 20 are connected through optical fibers, or connected through self-contained optical fibers.
The pump light source 51 may be a semiconductor pump light source, or may be any laser light source output by an optical fiber. For example, the pumping light source 51 may include at least one of a semiconductor laser, a direct semiconductor laser, and a short wavelength fiber laser. Further, the pump light may be pump light emitted from a semiconductor pump light source, and the wavelength thereof may be 900nm to 1000nm.
The cavity 52 may be a cavity of a laser, in which a gain medium may be disposed, and the signal light is finally obtained by continuously absorbing the pump light injected into the cavity 52 by the gain medium. Wherein the wavelength and effect of the pump light injected into the cavity 52 are different from those of the pump light provided by the pump light source 51. The pump light injected into the resonator 52 serves to generate pump light that amplifies the signal light.
The output element 53 may be a passive optical fiber having a refractive index distribution matching that of the special optical fiber 10, and the composite laser light output from the special optical fiber 10 is output from the output element 53.
It is understood that the composite laser is a laser in which the central region is the target signal light and the outer annular region is the first pump component.
The laser provided by the embodiment of the invention can output the composite light spot with high light spot energy in the central area and high light spot brightness in the outer annular area due to the introduction of the special optical fiber, has a simple structure, and can be suitable for scenes with high requirements on the light spot output by the laser, namely, the light spot with high energy in the middle area and the light spot with high brightness in the edge area. The laser device outputs two (or more) composite lasers with different powers, different wavelengths and different spot qualities simultaneously in a single optical fiber output head. Because the first pumping component in the pumping light is directly output, and part of the signal light in the cladding can be utilized, the wall-plug efficiency of the laser can be higher than that of a traditional optical fiber laser, and the advantages of a direct semiconductor laser and the optical fiber laser are combined. The spot in the annular region has a higher brightness. The high-brightness annular light spot enables the beam energy to be more concentrated, and the requirement on preheating power in the subsequent processing application can be further reduced.
On the basis of the embodiment, the output element is a passive optical fiber;
the passive optical fiber has the same refractive index profile as the specialty optical fiber.
Specifically, in order to ensure that the composite light spot output by the special optical fiber is identical to the composite light spot output by the laser, that is, in order to reduce the influence of the output element on the composite light spot output by the special optical fiber, the passive optical fiber can be configured to have the same refractive index distribution as the special optical fiber.
On the basis of the embodiment, the device further comprises a beam combining element, wherein the input end of the beam combining element is respectively connected with the output end of the pumping light source and the output end of the resonant cavity;
the beam combining element is used for combining the pump light and the signal light, and inputting a beam combining result into the special optical fiber so that the signal light is incident to the fiber core of the special optical fiber, and the pump light is incident to the waveguide layer or the waveguide layer and the angular spectrum screening layer of the special optical fiber.
Specifically, as shown in fig. 6, the laser 20 further includes a beam combining element 54, and the beam combining element 54 may be a beam combiner having two input ends and one output end, where the two input ends may be connected to the output end of the pump light source 51 and the output end of the resonant cavity 52, respectively, and the one output end is used for inputting a result of combining the pump light and the signal light into the special optical fiber 10.
After that, the signal light is incident on the core 1 of the special optical fiber 10, and the pump light is incident on the waveguide layer 4 of the special optical fiber 10 or on the waveguide layer 4 and the angular spectrum screening layer 3 of the special optical fiber 10.
In the embodiment of the invention, the beam combining element is introduced to optically couple the pump light and the signal into the special optical fiber, so that the difficulty of accessing the pump light and the signal light into the special optical fiber can be reduced, the access accuracy is improved, and the effect of outputting the composite light spot is further improved.
As shown in fig. 7, on the basis of the above embodiment, a laser processing system 30 is further provided in the embodiment of the present invention, which includes a welding head 71 and the laser 20 provided in each embodiment, where the welding head 71 is connected to the output element 53 in the laser 20, and is used to image a composite light spot of the composite laser light output by the laser to the workpiece 72 to be processed for processing.
In particular, the laser machining system 30 may be used for laser welding, laser cladding, or other laser applications. Further, the laser welding may be laser continuous welding. The laser continuous welding may be a processing mode different from spot welding, and the laser processing system may continuously output laser light to process the workpiece 72 to be processed.
In the embodiment of the invention, the laser processing system 30 can process the workpiece 72 to be processed by outputting composite laser at the laser 20 and a special optical fiber 10, preheat the surface of the workpiece 72 to be processed by using the annular region of the composite laser to form a smoother molten pool, and form a keyhole on the preheated region of the surface of the workpiece 72 to be processed by using the central region of the composite laser to obtain larger penetration depth, and the two light beams are not required to be combined by using an additional composite welding head, so that the processing cost is reduced. Meanwhile, the requirement of the annular region of the composite laser on the preheating power in the welding process can be further reduced.
The apparatus embodiments described above are merely illustrative, wherein the elements illustrated as separate elements may or may not be physically separate, and the elements shown as elements may or may not be physical elements, may be located in one place, or may be distributed over a plurality of network elements. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art will understand and implement the present invention without undue burden.
From the above description of the embodiments, it will be apparent to those skilled in the art that the embodiments may be implemented by means of software plus necessary general hardware platforms, or of course may be implemented by means of hardware. Based on this understanding, the foregoing technical solution may be embodied essentially or in a part contributing to the prior art in the form of a software product, which may be stored in a computer readable storage medium, such as ROM/RAM, a magnetic disk, an optical disk, etc., including several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the method described in the respective embodiments or some parts of the embodiments.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (13)
1. A specialty fiber, comprising: the fiber core comprises a first silicon dioxide layer, an angular spectrum screening layer and a waveguide layer which are sequentially arranged on the outer side of the fiber core in a surrounding manner;
the fiber core is used for accessing signal light;
the waveguide layer is used for accessing pump light;
the angular spectrum screening layer is used for binding a first pumping component which is not lower than a brightness threshold value in the pumping light and allowing a second pumping component which is lower than the brightness threshold value to pass through the angular spectrum screening layer and the first silicon dioxide layer to the fiber core so as to amplify the signal light in the fiber core; the brightness threshold is characterized by the numerical aperture of the angular spectrum screening layer;
the refractive index of the angular spectrum screening layer is larger than that of the first silicon dioxide layer;
the fiber core is also used for outputting amplified target signal light, the angular spectrum screening layer is also used for outputting the first pumping component, and the target signal light and the first pumping component form a composite light spot.
2. The special optical fiber according to claim 1, wherein,
the waveguide layer comprises a second silicon dioxide layer and an outer cladding layer, the second silicon dioxide layer is arranged on the outer side of the angular spectrum screening layer in a surrounding mode, and the outer cladding layer is arranged on the outer side of the second silicon dioxide layer in a surrounding mode;
the second silica layer has a refractive index higher than the refractive index of the outer cladding layer.
3. The specialty fiber of claim 1, wherein the power of the composite spot is tuned based on the power of the pump light and the power of the signal light.
4. The specialty fiber of claim 3, wherein said composite spot comprises a central region and an annular region;
the power of the central region is determined based on the power of the signal light, the power of the pump light, the duty ratio of the second pump component, and the luminous efficiency;
the power of the annular region is determined based on the power of the pump light and the duty cycle of the first pump component.
5. The specialty fiber of claim 4, wherein the first pump component is determined based on the energy spectral density of the pump light and the numerical aperture of the angular spectrum screening layer;
the duty cycle of the second pump component is determined based on the duty cycle of the first pump component or based on the energy spectral density of the pump light and the numerical aperture of the angular spectral screening layer.
6. The specialty fiber of claim 5, wherein the power of said central area is determined based on the formula:
；
the power of the annular region is determined based on the following formula:
；
wherein ,for the power of the central region, +.>For the power of the annular region, +.>For the energy spectral density of the pump light,NAscreening the angular spectrum for the numerical aperture of the layer, < >>For luminous efficiency, +.>For the power of the pump light, +.>For the power of the signal light, +.>For the duty cycle of the second pump component, < > and>is the duty cycle of the first pump component.
7. The specialty fiber of claim 2 wherein said outer cladding is doped with fluoride or boron ions.
8. The specialty fiber of any of claims 1-7, wherein said core is doped with rare earth ions.
9. The specialty fiber of any of claims 1-7, wherein said angular spectrum screening layer is doped with germanium ions.
10. A laser comprising a pump light source, a resonant cavity, an output element and a specialty fiber according to any of claims 1 to 9;
the pump light source is used for providing the pump light for the special optical fiber;
the resonant cavity is used for providing the signal light for the special optical fiber;
the output element is used for transmitting the composite laser output by the special optical fiber.
11. The laser of claim 10, wherein the output element is a passive optical fiber;
the passive optical fiber has the same refractive index profile as the specialty optical fiber.
12. The laser of claim 10, further comprising a beam combining element having an input coupled to the output of the pump light source and the output of the resonant cavity, respectively;
the beam combining element is used for combining the pump light and the signal light, and inputting a beam combining result into the special optical fiber so that the signal light is incident to the fiber core of the special optical fiber, and the pump light is incident to the waveguide layer or the waveguide layer and the angular spectrum screening layer of the special optical fiber.
13. A laser processing system comprising a welding head and a laser as claimed in any one of claims 10 to 12, the welding head being connected to an output element in the laser for imaging a composite spot of composite laser light output by the laser onto a workpiece to be processed.
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