CN103018820A - Flat-top optical fiber - Google Patents
Flat-top optical fiber Download PDFInfo
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- CN103018820A CN103018820A CN2012105826428A CN201210582642A CN103018820A CN 103018820 A CN103018820 A CN 103018820A CN 2012105826428 A CN2012105826428 A CN 2012105826428A CN 201210582642 A CN201210582642 A CN 201210582642A CN 103018820 A CN103018820 A CN 103018820A
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- refractive index
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Abstract
The invention discloses a flat-top optical fiber. A host material (1) and high-refractive-index dielectric cylinders (2) arranged in regular grids form a fiber core, and the host material (1) and low-refractive-index holes (3) form a covering layer. The refractive index nh of the high-refractive-index dielectric cylinders is larger than the refractive index nb of the host material, and the refractive index nl of the low-refractive-index holes is smaller than the refractive index nb of the host material. The diameter dm of the outmost high-refractive-index dielectric cylinders of the fiber core is larger than the diameter dh of other high-refractive-index dielectric cylinders. The high-refractive-index dielectric cylinders of different sizes are adopted to form refractive index distribution required by flat-top light beams, the technical obstacle of failure in practical manufacturing due to excessively small changes of refractive index distribution of the fiber core when a normal optical fiber structure is adopted. The low-refractive-index holes are used for constraining light to enable steep optical field distribution of light beams. The flat-top optical fiber can be applied to output ends of optical fiber lasers to realize flat-top light beam output in large mode fields.
Description
Technical field
The present invention relates to the fiber laser field, be specially a kind of flat-top optical fiber of big mode field area characteristic.
Background technology
It has been an indispensable link in the Laser Processing that laser beam is carried out shaping, for example in laser bonding, in order to obtain preferably welding effect, solder joint is heated evenly, and this is flat-head type with regard to the optical field distribution that requires laser beam.The method that obtains the flat-top laser beam is a lot, and wherein a kind of method is to utilize flat-top optical fiber incoming laser beam to be shaped as the laser beam with flat-head type optical field distribution.So-called flat-top optical fiber, the laser beam of namely exporting through its has the mode-field structure of flat-head type.As everyone knows, the light field of laser beam on cross section of optic fibre from ordinary optic fibre output is to be the class gaussian shaped profile.Obtain the light field of flat-head type, will adopt special optical fiber structure.The leaded light principle of ordinary optic fibre is all optical communication, and its basic structure is: internal layer is core region, and skin is clad region, and the refractive index of the refractive index ratio clad region of core region is slightly large, in order to light is constrained in core region and forward transmission.Because near the refractive index the ordinary optic fibre axle center is larger, causes the laser light field of fiber-optic output inhomogeneous in cross direction profiles, be Gauss or nearly gaussian shaped profile.
In order to obtain flat top beam, need to improve optical fiber structure.A kind of structure slightly proposed (beam shaping optical fibre, application number: 200410024873.2) than the beam shaping optical fibre of ordinary optic fibre complexity by people such as Lu Xingqiang, Zhou Qinling in 2004.This optical fiber comprises core region and clad region, and different with ordinary optic fibre is that its core region and clad region all are comprised of two-layer.Core region comprises interior core region and outer core region, and outer core region is filled high-index material, and interior core region is formed by low-index material, and the shape of this core region is consistent with the shape of optical fiber output facula.Clad region is comprised of inner cladding region and outer cladding region, and the refractive index of inner cladding region material therefor is less than the refractive index of interior core region, and outer cladding region is formed by the material of low-refraction more.This beam shaping optical fibre can carry out spacing shaping to the laser that imports, obtain the Laser output of light field middle part flat-top or medial recess, collapse side effect and design of the gain that can be applied to laser shaping, homogenising, compensate for laser has in the fields such as fiber laser of special light field distribution.
During the transmission high power laser light, in order effectively to reduce nonlinear effect to the impact of transmitting beam, need to adopt the optical fiber with big mode field area.When high power laser light uses, in order to obtain uniform and stable Laser output, need equally the optical fiber of flat-head type beam distribution.Flat-top optical fiber technology with big mode field area is anxious to be developed.
Summary of the invention
For above deficiency, the objective of the invention is to propose a kind of novel optical fiber that has big mode field area and can realize flat top beam output.
Technical scheme of the present invention is: comprise fibre core and covering, it is characterized in that: described fibre core is comprised of host material and the high refractive index medium post that is arranged in the regular grid, and described covering is comprised of host material (1) and low-refraction hole; The refractive index n of described high refractive index medium post
hRefractive index n greater than host material (1)
b, the refractive index n in described low-refraction hole
lRefractive index n less than host material
b, the high refractive index medium column diameter d of outermost one deck in the described fibre core
mHigh refractive index medium column diameter d greater than internal layer
h, the diameter d in described low-refraction hole
lHigh refractive index medium column diameter d greater than outermost one deck
m
As a further improvement on the present invention, the span of the periods lambda of described high refractive index medium post is: 3 ~ 8 μ m; The high refractive index medium column diameter d of the periods lambda of described high refractive index medium post, outermost one deck
mHigh refractive index medium column diameter d with internal layer
hBetween the pass be: d
m/ Λ=0.3 ~ 0.8, d
h/ Λ=0.1 ~ 0.4, and d is arranged
m-d
h〉=0.05 Λ; The refringence of described high refractive index medium post and host material is closed: n
h-n
b=0.001 ~ 0.003.
Described low-refraction hole is airport or is comprised of the quartz material that mixes; The diameter d in described low-refraction hole
lSpan be: 10 ~ 40 μ m.
Technique effect of the present invention: adopt the high refractive index medium post of different size to form the required index distribution of flat top beam, when having solved employing ordinary optic fibre structure, the index distribution of fibre core changes too small and technology barrier can't actual fabrication.Adopt low-refraction hole constraint light, and make light beam have steep optical field distribution.Optical fiber of the present invention can be applied to optical fiber laser output end, to realize the flat top beam output of large mould field.
Description of drawings
The radial refractive index distribution synoptic diagram of the symmetrical flat-top optical fiber of a kind of common circle of Fig. 1;
Fig. 2 is the mould field pattern of structure shown in Figure 1;
Fig. 3 is a kind of cross-sectional structure synoptic diagram of optical fiber of the present invention;
The mould field pattern of Fig. 4 optical fiber of the present invention;
Wherein, 1 is host material, and 2 is the high refractive index medium post, and 3 is the low-refraction hole.
Embodiment
The basic mode of ordinary optic fibre has the Gaussian field distribution, if will obtain the flat-head type light field, can be by reducing the refractive index of core centre, thus make light field to the expansion of the fibre core outside, form flat top beam, as shown in Figure 1.When requiring optical fiber to be large mould field optical fiber, require the fibre core zones of different to have little refringence.For example, when core diameter was 30 microns, the refractive index decrease of the fibre core inside of its requirement was 10
-4Magnitude.This is so that the extremely difficult realization of general optical fiber fabrication technique.Simultaneously, the accuracy requirement of the optical fiber birefringence rate variance of this structure is also very high.For example, Fig. 2 (a) and (b) to be respectively in the structure shown in Figure 3 when fibre core two parts refringence be 0.0008 and 0.0006 result, as seen both mould field distribution are fully different.Therefore, this flat-top optical fiber fabrication difficulty is very large.
For this reason, it is the less high refractive index medium post 2 of diameter that the present invention proposes to adopt fibre core inner, the outside larger high refractive index medium post 2 of diameter that adopts of fibre core, thereby the index distribution of acquisition better effects if.Can regulate the equivalent refractive index of fibre core zones of different by cycle and the diameter of adjusting the medium post, thereby make the index distribution of core region more accurate.When making, the refractive index of high refractive index medium post is identical, has also reduced the complexity of manufacture craft, simultaneously, has also overcome the poor difficulty of low-refraction that directly obtains the fibre core zones of different by mixing.
When distance between the high refractive index medium post was very large, its structure just became a kind of multi-core fiber, i.e. light independent transmission in the different medium post.For obtaining flat top beam output, the spacing of medium post can not be excessive.Simultaneously, the medium column diameter is too small, also can cause the optical fiber fabrication difficulty.Therefore, requiring the centre distance (being the periods lambda of medium post) of adjacent high refractive index medium post 2 is 3 ~ 8 μ m.Because the cycle variation range of medium post is limited, in order to obtain the flat-top optical fiber of different mode field areas, the quantity of capable of regulating medium post realizes.
For ease of making, high refractive index medium post 2 can not be too small with the refringence of host material 1.The refringence pass of generally getting high refractive index medium post 2 and host material 1 is: n
h-n
b=0.001 ~ 0.003.Because both refractive indexes are larger, in order to make the distribution of light field in fibre core comparatively even, high refractive index medium post proportion in fibre core is smaller.The size of the outermost high refractive index medium post 2 of fibre core can be larger, thereby light field is extended to the fibre core outside.Therefore, require the periods lambda of high refractive index medium post, the diameter d of high refractive index medium post
m, d
hBetween the pass be: d
m/ Λ=0.3 ~ 0.8, d
h/ Λ=0.1 ~ 0.4, and d is arranged
m-d
h〉=0.05 Λ.
Constraint light is mainly played in low-refraction hole 3 in the covering.Because the equivalent refractive index of fibre core is general only a little more than the refractive index of host material, in order effectively to fetter light, needs to reduce the refractive index of covering.The introducing in low-refraction hole 3 can realize fettering the purpose of light effectively.By the theory of microstructured optical fibers, low-refraction hole 3 refractive indexes own can be very low, but its equivalent cladding index can be higher.Therefore, can make fibre core and covering keep less refringence, reduce the appearance of high-order mode.Simultaneously, the refractive index in low-refraction hole 3 itself is lower, can establishment light to the expansion of clad region, can make the edge of flat-top die field more steep.Low-refraction hole 3 can form for airport or by the quartz material that mixes.Its diameter d
lTypical span be: 10 ~ 40 μ m.
Embodiment:
Optical fiber structure as shown in Figure 3.Host material 1 is pure quartz, and high refractive index medium post 2 is 0.0015 with the refringence of host material 1, and the diameter of high refractive index medium post is respectively d
m=2.4 μ m, and d
h=1.2 μ m.Low-refraction hole 3 is 0.005 with the refringence of host material 1, and the diameter in low-refraction hole 3 is 26 μ m, and low-refraction hole 3 is 40 μ m with the distance of fiber optic hub.The mould field distribution of optical fiber as shown in Figure 4.During optical fiber fabrication, can adopt the substep method of piling to make preform.Namely at first make fiber core with method of piling, the fibre core that then will obtain through wire drawing and quartz ampoule or the combination of doping quartz pushrod obtain required optical fiber structure through wire drawing again.
Above-mentioned accompanying drawing only is explanatory view, protection scope of the present invention is not formed restriction.Should be understood that these embodiment just in order to demonstrate the invention, but not limit the scope of the invention by any way.
Claims (5)
1. flat-top optical fiber, comprise fibre core and covering, it is characterized in that: described fibre core is comprised of host material (1) and the high refractive index medium post (2) that is arranged in the regular grid, and described covering is comprised of host material (1) and low-refraction hole (3); The refractive index n of described high refractive index medium post (2)
hRefractive index n greater than host material (1)
b, the refractive index n in described low-refraction hole (3)
lRefractive index n less than host material (1)
b, high refractive index medium post (2) diameter d of outermost one deck in the described fibre core
mHigh refractive index medium post (2) diameter d greater than internal layer
h, the diameter d in described low-refraction hole (3)
lHigh refractive index medium post (2) diameter d greater than outermost one deck
m
2. a kind of flat-top optical fiber according to claim 1, it is characterized in that: the span of the periods lambda of described high refractive index medium post (2) is: 3 ~ 8 μ m; High refractive index medium post (2) diameter d of the periods lambda of described high refractive index medium post (2), outermost one deck
mHigh refractive index medium post (2) diameter d with internal layer
hBetween the pass be: d
m/ Λ=0.3 ~ 0.8, d
h/ Λ=0.1 ~ 0.4, and d is arranged
m-d
h〉=0.05 Λ.
3. a kind of flat-top optical fiber according to claim 1 is characterized in that: described high refractive index medium post (2) closes with the refringence of host material (1) and is: n
h-n
b=0.001 ~ 0.003.
4. a kind of flat-top optical fiber according to claim 1 is characterized in that: described low-refraction hole (3) forms for airport or by the quartz material that mixes.
5. a kind of flat-top optical fiber according to claim 1 is characterized in that: the diameter d in described low-refraction hole (3)
lSpan be: 10 ~ 40 μ m.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210582642.8A CN103018820B (en) | 2012-12-28 | 2012-12-28 | Flat-top optical fiber |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210582642.8A CN103018820B (en) | 2012-12-28 | 2012-12-28 | Flat-top optical fiber |
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| CN103018820A true CN103018820A (en) | 2013-04-03 |
| CN103018820B CN103018820B (en) | 2014-06-25 |
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|---|---|---|---|
| CN201210582642.8A Expired - Fee Related CN103018820B (en) | 2012-12-28 | 2012-12-28 | Flat-top optical fiber |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104316991A (en) * | 2014-11-05 | 2015-01-28 | 国家电网公司 | Flat-top photonic band gap fiber |
| CN106908894A (en) * | 2017-03-23 | 2017-06-30 | 燕山大学 | A kind of dispersion flattene consolidates microstructured optical fibers entirely |
| CN109283637A (en) * | 2018-11-13 | 2019-01-29 | 南京理工大学 | One kind being used for the homogenized fiber coupled laser of interference pattern background |
| CN114740566A (en) * | 2022-03-11 | 2022-07-12 | 中国科学院西安光学精密机械研究所 | Polymer microstructure optical fiber for terahertz wave high-performance imaging and optical fiber image transmission bundle |
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| US20040114897A1 (en) * | 2002-12-10 | 2004-06-17 | Sumitomo Electric Industries, Ltd. | Optical fiber |
| JP2004184635A (en) * | 2002-12-02 | 2004-07-02 | Occ Corp | Submarine optical cable and coated optical fiber |
| US20050018986A1 (en) * | 2001-12-17 | 2005-01-27 | Alexander Argyros | Ring structures in optical fibres |
| CN1584644A (en) * | 2004-06-02 | 2005-02-23 | 中国科学院上海光学精密机械研究所 | Beam shaping optical fibre |
| US20050157998A1 (en) * | 2004-01-16 | 2005-07-21 | Liang Dong | Large core holey fibers |
| CN101339273A (en) * | 2008-08-12 | 2009-01-07 | 江苏大学 | Optical fibre mode converter |
| EP2455788A1 (en) * | 2009-07-17 | 2012-05-23 | Sumitomo Electric Industries, Ltd. | Photonic crystal fiber |
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2012
- 2012-12-28 CN CN201210582642.8A patent/CN103018820B/en not_active Expired - Fee Related
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20050018986A1 (en) * | 2001-12-17 | 2005-01-27 | Alexander Argyros | Ring structures in optical fibres |
| JP2004184635A (en) * | 2002-12-02 | 2004-07-02 | Occ Corp | Submarine optical cable and coated optical fiber |
| US20040114897A1 (en) * | 2002-12-10 | 2004-06-17 | Sumitomo Electric Industries, Ltd. | Optical fiber |
| US20050157998A1 (en) * | 2004-01-16 | 2005-07-21 | Liang Dong | Large core holey fibers |
| CN1584644A (en) * | 2004-06-02 | 2005-02-23 | 中国科学院上海光学精密机械研究所 | Beam shaping optical fibre |
| CN101339273A (en) * | 2008-08-12 | 2009-01-07 | 江苏大学 | Optical fibre mode converter |
| EP2455788A1 (en) * | 2009-07-17 | 2012-05-23 | Sumitomo Electric Industries, Ltd. | Photonic crystal fiber |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104316991A (en) * | 2014-11-05 | 2015-01-28 | 国家电网公司 | Flat-top photonic band gap fiber |
| CN104316991B (en) * | 2014-11-05 | 2017-10-31 | 国家电网公司 | Flat-top photon band-gap optical fiber |
| CN106908894A (en) * | 2017-03-23 | 2017-06-30 | 燕山大学 | A kind of dispersion flattene consolidates microstructured optical fibers entirely |
| CN106908894B (en) * | 2017-03-23 | 2020-01-07 | 燕山大学 | Chromatic dispersion flat full-solid microstructure optical fiber |
| CN109283637A (en) * | 2018-11-13 | 2019-01-29 | 南京理工大学 | One kind being used for the homogenized fiber coupled laser of interference pattern background |
| CN114740566A (en) * | 2022-03-11 | 2022-07-12 | 中国科学院西安光学精密机械研究所 | Polymer microstructure optical fiber for terahertz wave high-performance imaging and optical fiber image transmission bundle |
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| CN103018820B (en) | 2014-06-25 |
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Address after: 212114 Zhenjiang, Zhejiang Province, Dantu high capital street, Xiangshan Road, No. 1 Patentee after: Jiangsu University Address before: 211200 Jiangsu Province, Lishui District Yong Yang Town Bridge Road, No. 688 Patentee before: Jiangsu University |
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