CN104635296A - Long-distance laser energy transmission optical fiber - Google Patents
Long-distance laser energy transmission optical fiber Download PDFInfo
- Publication number
- CN104635296A CN104635296A CN201410626272.2A CN201410626272A CN104635296A CN 104635296 A CN104635296 A CN 104635296A CN 201410626272 A CN201410626272 A CN 201410626272A CN 104635296 A CN104635296 A CN 104635296A
- Authority
- CN
- China
- Prior art keywords
- optical fiber
- refractive index
- covering
- cladding
- core
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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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
- G02B6/028—Optical fibres with cladding with or without a coating with core or cladding having graded refractive index
- G02B6/0283—Graded index region external to the central core segment, e.g. sloping layer or triangular or trapezoidal layer
Abstract
The invention discloses a long-distance laser energy transmission optical fiber. A fiber core is made of pure quartz, a cladding is made of fluorine doped quartz, and refractive index distribution of the cladding satisfies that refractive index of a corresponding point, in a distance r from the center of the fiber core, of the cladding is accordant with the equation: n(r)=n1+(n2-n1){(r-a1)/(a2-a1)}<2>, wherein n1 refers to the refractive index of the outer edge of the fiber core, n2 refers to the refractive index of the outer edge of the cladding, a1 refers to the radius of the fiber core, and a2 refers to the radius of the cladding. The refractive index of the cladding is gradually reduced outwards from the center of the optical fiber, mode field diameter of a basic mode can be effectively increased, and optical coupling and reduction of laser damages to the optical fiber are facilitated; by introduction of a gradually-changed refractive index distribution structure to the cladding, energy distribution of low-order modes in highly doped regions is reduced, and accordingly transmission loss is reduced; due to the fact that difference in refractive indexes of the outer edge of the cladding and the fiber core is still high and even can be higher, large numerical aperture of the optical fiber is guaranteed to further guarantee that laser can be effectively inputted and coupled into the optical fiber.
Description
Technical field
The present invention relates to fiber laser transmission field, be specially a kind of Laser energy transmission optical fiber.
Background technology
Fiber laser obtains a wide range of applications in field of laser processing, due to the flexibility of optical fiber, it can be applied to some special occasions, as carried out the occasion of laser treatment at narrow space, high-capacity optical fiber laser also for imderwater cutting provide efficiently, safety, the new method of environmental protection and approach.For adapting to the needs such as narrow space, underwater operation, require that laser is by the long distance of the dozens or even hundreds of rice of Optical Fiber Transmission, and the length of current most Laser energy transmission optical fiber is all at about 10 meters, this just significantly limit the application of fiber laser in these occasions.The Laser Transmission of long distance is had higher requirement to fibre-optic transmission system (FOTS), and on the one hand, the transmission of long distance needs the loss reducing optical fiber, thus ensures that output terminal has larger Output optical power; On the other hand, when there is certain loss, the laser power of injection fibre should be increased, thus increase fiber-optic output laser output power.
Most Laser energy transmission optical fiber uses pure silica core optical fiber, and its structure is common step index fiber structure, and namely fiber core refractive index is high, and cladding index is low, fibre core and cladding regions refractive index constant, this structure is the simplest.Its covering is divided into silica clad type and the large class of plastic packets stratotype two.Silica clad type energy optical fiber can transmit higher laser power, has good anti-light lesion capability and lower decay and higher light transmission rate (being 400nm ~ 1600nm near ultraviolet band to near-infrared band); The numerical aperture of plastic packets stratotype energy optical fiber is larger, be conducive to optically-coupled, but its anti-light functipnal capability is weaker than silica cladded fibre.For reducing the optical power density of Optical Fiber Transmission, avoid optical fiber to damage, the core diameter of Laser energy transmission optical fiber is generally between 100 ~ 1000 μm, and relative transport distance shorter (being less than 10m) is typical multimode optical fiber.Increase core size and can reduce optical power density, be conducive to reducing optical damage, but the flexibility of optical fiber also can be caused to be deteriorated, easy fracture.Because fibre diameter is larger, its mechanical bend performance is poorer, and therefore, desirable Laser energy transmission optical fiber under same fibre diameter, should have larger mode field area.
Laser energy transmission optical fiber should have low-loss and better stability, at 1064nm wave band, the loss of current complete quartzy Laser energy transmission optical fiber can reach 10 below dB/km, and spillage of material is the key factor of limit fibre loss, in addition, the leakage losses that high-order mode causes is a wherein important factor, on the other hand, during long range propagation, laser is subject to the impact of fibre-optical bending and extraneous stress, produce bending loss, this is one of key factor of restriction high power laser light transmission range.Loss not only decreases the laser power that optical fiber exports, and also brings the problems such as Transmission Fibers heat radiation, directly affects the distance of Optical Fiber Transmission high power laser light.
In recent years, occurred employing microstructured optical fibers [All-glass large-core leakage channel fibers (full glass large fibre core passage reveal optical fiber). IEEE J. Sel. Top. Quant. Electron.,
15(1): 47-53,2009], air-core photonic band pbg fiber [Hollow-core photonic crystal fibre for high power laser beam delivery (hollow-core photonic crystal fiber be used for high power laser light transmission). High Power Laser Science and Engineering
1(01): 17-28,2013], Bragg optical fiber [Solid-core photonic bandgap fibers for high-power fiber lasers (all solid state band gap fiber for high power optical fibre laser). IEEE Journal of Selected Topics in Quantum Electronics
15(1): 20-29,2009] etc. novel optical fiber structure is to transmit high power laser light, and except obtaining in dirigibility and Characteristics of modes and improving, the power of these novel optical fibers transmission laser not yet can exceed complete quartzy multimode optical fiber.
Laser energy transmission fiber end face damage threshold wants high.For obtaining high-power Laser output, under the prerequisite that there is certain loss, need the luminous power as far as possible improving energy-transmission optic fibre input end.Research shows: during high power laser light transmission, its damage often first from end face [fiber end face Nd:YAG Laser Induced Damage is analyzed. Acta Optica,
29(4): 923-926,2009].Except the method by increasing core area reduces end face optical power density, the method increasing input end face is adopted also to be a kind of wherein conventional method.
Due to the restriction of above-mentioned technology, yet there are no and grow distance and the Laser energy transmission optical fiber that can transmit high power laser light.
Summary of the invention
The object of the invention is for the deficiencies in the prior art, a kind of effective reduction fiber transmission attenuation is provided, increase laser input optical power and the Laser energy transmission optical fiber of the long range propagation of applicable dozens or even hundreds of rice.
For realizing object of the present invention, the technical solution used in the present invention is: the present invention is made up of fibre core and covering two parts, fibre core adopts pure quartz, covering is made up of the quartz mixing fluorine, cladding index is outwards reduced gradually by fiber optic hub, and the index distribution of covering meets: with the refractive index of the covering respective point at core centre distance r place be:
,
for the refractive index of fibre core outer,
for the refractive index of covering outer,
for the radius of fibre core,
for the radius of covering.
The refractive index of described fibre core outer
with the refractive index of covering outer
difference meet 0.01<
-
<0.025.
The radius of described fibre core
the best is 100 ~ 1000 μm, cladding layer width
d=
-
the best is 10 ~ 80 μm.
Technique effect of the present invention is:
1) covering of the present invention is graded index cladding structure, effectively can increase the mode field diameter of basic mode, contributes to the coupling of light and reduces laser to the damage of optical fiber.
2) the present invention is by introducing graded--index planar waveguides structure at covering, decrease the energy distribution of low-order mode in high-doped zone, thus reduce its loss (its spillage of material of doping multizone is high), simultaneously, because covering outer and fiber core refractive index difference are still very large, even can be higher, ensure that the large-numerical aperture that optical fiber has, ensure that laser can effectively input and be coupled in optical fiber.
3) method for making of the present invention and existing fiber manufacture craft compatibility, have the feature of transmission high power laser light, low transmission loss.
Accompanying drawing explanation
Fig. 1 is the radial refractive index distribution schematic diagram of the optical fiber in embodiment 1;
Fig. 2 is fiber core radius is in the step change type energy-transmission optic fibre of 52.5 μm, and the graph of relation of the coupling efficiency of input field and different mode, wherein, curve A is LP
01the coupling efficiency of mould, curve B is LP
02the coupling efficiency of mould, curve C is LP
03the coupling efficiency of mould;
Fig. 3 is the radial surface of intensity distribution of optical fiber of the present invention.
Embodiment
The present invention is made up of fibre core and covering two parts, and fibre core is made up of pure quartz, and covering is made up of the quartz mixing fluorine.Covering is coat, and coat adopts ultraviolet light polymerization high index of refraction coating, and also can adopt double-coating coating, the interlayer coatings of double-coating coating is ultraviolet light polymerization low-refraction silicon rubber, and outer layer coating is ultraviolet light polymerization high index of refraction coating.
The fibre core of optical fiber of the present invention adopts pure quartz, and to reduce the reduction of the loss of doping to Laser Transmission and the damage threshold to optical fiber, the covering of optical fiber adopts the quartz composition mixing fluorine.The index distribution of covering meets: with the refractive index of the covering respective point at core centre distance r place be:
, wherein,
for the refractive index of fibre core outer,
for the refractive index of covering outer,
for the radius of fibre core,
for the radius of covering, cladding layer width
,
for the distance of covering respective point and core centre.It can thus be appreciated that cladding index is outwards reduced gradually by fiber optic hub, it is a kind of graded index structure.
Compare conventional simple step change type energy transmission optical fibre structure, and the ratio of doped cladding layer fluorine of the present invention is determined according to index requirements, and the ratio of mixing fluorine is obtained by following formula: d
f=(n
silica-n
f)/4.665 × 10
-3(mol%), in formula, n
silicafor the refractive index of pure quartz, n
ffor the refractive index of fluorine-doped quartz.For pure quartz, its refractive index n
silicacan be obtained by following formula:
, the numerical value of each term coefficient in formula is:
=0.6961663,
=0.0684043 × 10
-6,
=0.4079426,
=0.1162414 × 10
-6,
=0.8974794,
=9.896161 × 10
-6,
it is optical wavelength.Work as optical wavelength
when being 1064 nm, refractive index n
silica=1.44963.
The radius of fibre core
the best is 100 ~ 1000 μm, corresponding cladding layer width
dthe best is 10 ~ 80 μm.The refractive index of fibre core outer
with the refractive index of covering outer
difference should meet 0.01<
-
<0.025.The refractive index of covering outer
with the refractive index of fibre core outer
difference still can reach the level of step change type energy-transmission optic fibre even can be higher, thus ensure that optical fiber still has large numerical aperture, therefore it still can effectively collect input laser.Meanwhile, owing to not increasing fibre diameter, do not affect the mechanical bend performance of optical fiber.
Long its transmission range of distance Laser energy transmission optical fiber provided by the invention can reach 50 ~ 400 m.
Below provide 3 embodiments of the present invention, with silica fibre, operation wavelength is 1064 nm is example.
embodiment 1
See the xsect radial refractive index distribution of the optical fiber of the present invention of Fig. 1, ordinate is refractive index n, and horizontal ordinate is fiber radius R.Fig. 1 center line 1 is the radial refractive index distribution line of fibre core, and line 2 is radial refractive index distribution lines of covering.Host material adopts pure quartz, and covering is the quartz mixing fluorine.Wherein fiber core radius
=52.5 μm, cladding radius
=62.5 μm, i.e. cladding layer width
d=10 μm, the refractive index of fibre core outer
=1.44963, the refractive index of covering outer
=1.43663, namely have
-
=0.013.The foundational model field diameter of optical fiber can reach 78.5 μm, and basic mode light intensity drops to less than 0.1% of core centre energy at distance core centre 53.5 μm of places.The covering that this position is corresponding and fiber core refractive index difference are only 0.0003.Therefore, optical fiber basic mode can transmit in low doped region, and its loss can low 0.5 more than dB/km compared to step change type energy-transmission optic fibre.
Fig. 2 is fiber core radius is in the step change type energy-transmission optic fibre of 52.5 μm, the relation curve of the coupling efficiency of input field and different mode.In figure, horizontal ordinate is the mode field diameter of input field.Ordinate is the coupling efficiency of the corresponding modes in input field and step change type energy-transmission optic fibre.In Fig. 2, curve A, B, C refer to the LP in step optical fiber respectively
01, LP
02, LP
03the coupling efficiency of mould.As seen from Figure 2, optical fiber basic mode (i.e. LP
01mould) to account for transmitting energy ratio in optical fiber the highest for energy, even if when input field effective diameter reaches 125 μm, its coupling efficiency still can reach more than 70%.Therefore, the transmission situation of optical fiber basic mode will be the principal element determining Laser energy transmission performance.
Fig. 3 is the radial surface of intensity distribution of optical fiber of the present invention.As seen from Figure 3, outside along core centre, its light intensity energy is class Gaussian, and in clad region, its light intensity value is very little.
By optical-fiber laser defect theory, optical power density during Optical Fiber Transmission is lower, and optical fiber is more not easy to produce damage.For this reason, analyze and there is identical fibre core but the mode field diameter situation of cladding index distributes different three kinds of optical fiber (step change type energy-transmission optic fibre, optical fiber of the present invention and covering adopt the energy-transmission optic fibre of linear refractive index change curve).Such as, core parameters is identical, fibre core is also identical with covering (or covering outer) refringence step change type energy-transmission optic fibre, optical fiber of the present invention and covering adopt the foundational model field diameter of the energy-transmission optic fibre of linear refractive index change curve to be respectively: 73.5,78.5,76 μm.Visible, optical fiber of the present invention has maximum mode field diameter.According to mode field area computing formula, can obtain: optical fiber of the present invention increases 14% than the mode field area of step change type energy-transmission optic fibre.And be the energy-transmission optic fibre of graded index structure, single refractive index cladding structure according to fibre core, its mode field diameter is only 18.5 μm.Therefore, adopt optical fiber structure of the present invention, effectively can increase the mode field diameter of optical fiber basic mode, reduce laser to the damage of optical fiber.
Because fiber core is pure quartz, and covering is the quartz material of doping, and doping causes the increase of optical transmission loss and the reduction of laser damage threshold.The loss of doped region is directly related with doping.For this reason, the basic mode and the low step mode that make to account for most of energy appear at non-impurity-doped (core region) and low-doped clad region, thus decrease the optical transmission loss caused due to doping.As seen from Figure 3, its basic mode light distribution of optical fiber mainly concentrates on fibre core and low-doped region.In the clad region away from fibre core, highly doped (low-refraction), its energy distribution is few.Therefore, this structure can reduce the damage from laser and loss of adulterating and causing.
embodiment 2
Host material adopts pure quartz, and covering is the quartz mixing fluorine.Wherein fiber core radius
=100 μm, cladding radius
=115 μm, the refractive index of fibre core outer
with the refractive index of covering outer
both differences
-
=0.014.The foundational model field diameter of optical fiber can reach 145 μm, and basic mode light intensity drops to less than 0.1% of core centre energy at distance core centre 84 μm of places, and this position is still in core region.Therefore, optical fiber basic mode can transmit in low doped region, and its loss can low 0.6 more than dB/km compared to step structured optical fiber.
embodiment 3
Host material adopts pure quartz, and covering is the quartz mixing fluorine.Wherein fiber core radius
=300 μm, cladding radius
=330 μm, the refractive index of fibre core outer
with the refractive index of covering outer
both differences
-
=0.012.The foundational model field diameter of optical fiber can reach 424 μm, and basic mode light intensity drops to less than 0.1% of core centre energy at distance core centre 300 μm of places.Therefore, optical fiber basic mode can transmit in low doped region, and its loss can low 1 more than dB/km compared to step structured optical fiber.
Claims (5)
1. one kind long distance Laser energy transmission optical fiber, be made up of fibre core and covering two parts, it is characterized in that: fibre core adopts pure quartz, covering is made up of the quartz mixing fluorine, cladding index is outwards reduced gradually by fiber optic hub, and the index distribution of covering meets: with the refractive index of the covering respective point at core centre distance r place be:
,
for the refractive index of fibre core outer,
for the refractive index of covering outer,
for the radius of fibre core,
for the radius of covering.
2. long apart from Laser energy transmission optical fiber according to claim 1, it is characterized in that: the refractive index of fibre core outer
with the refractive index of covering outer
difference meet 0.01<
-
<0.025.
3. long apart from Laser energy transmission optical fiber according to claim 1, it is characterized in that: the radius of fibre core
the best is 100 ~ 1000 μm, cladding layer width
d=
-
the best is 10 ~ 80 μm.
4. long apart from Laser energy transmission optical fiber according to claim 1, it is characterized in that: the ratio d of doped cladding layer fluorine
f=(n
silica-n
f)/4.665 × 10
-3(mol%), n
silicafor the refractive index of pure quartz, n
ffor the refractive index of fluorine-doped quartz
,
=0.6961663,
=0.0684043 × 10
-6,
=0.4079426,
=0.1162414 × 10
-6,
=0.8974794,
=9.896161 × 10
-6,
it is optical wavelength.
5. long apart from Laser energy transmission optical fiber according to claim 1, it is characterized in that: covering is coat, coat adopts ultraviolet light polymerization high index of refraction dope layer or double-coating coating, the interlayer coatings of double-coating coating is ultraviolet light polymerization low-refraction silicon rubber, and outer layer coating is ultraviolet light polymerization high index of refraction coating.
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|---|---|---|---|
| CN201410626272.2A CN104635296A (en) | 2014-11-10 | 2014-11-10 | Long-distance laser energy transmission optical fiber |
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|---|---|---|---|
| CN201410626272.2A CN104635296A (en) | 2014-11-10 | 2014-11-10 | Long-distance laser energy transmission optical fiber |
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|---|---|
| CN104635296A true CN104635296A (en) | 2015-05-20 |
Family
ID=53214243
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106443871A (en) * | 2016-09-27 | 2017-02-22 | 南京鸿照科技有限公司 | Method for changing numerical aperture of plastic fiber |
| CN110073257A (en) * | 2016-07-29 | 2019-07-30 | 康宁股份有限公司 | Low-loss single-mode optical fiber with chlorine doped core |
| CN110224754A (en) * | 2018-03-02 | 2019-09-10 | 韩国光技术院 | Optical communication system |
| CN112099130A (en) * | 2020-09-25 | 2020-12-18 | 东北大学 | Slope-type refractive index distribution multi-core optical fiber with low crosstalk between cores |
| CN114839714A (en) * | 2022-04-27 | 2022-08-02 | 南京邮电大学 | Temperature-tunable ultra-negative dispersion twin-core photonic crystal fiber |
| CN117111206A (en) * | 2023-10-23 | 2023-11-24 | 武汉市飞瓴光电科技有限公司 | High non-linear quartz optical fiber |
Citations (4)
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|---|---|---|---|---|
| US4893896A (en) * | 1987-07-10 | 1990-01-16 | Mitsubishi Cable Industries, Ltd. | Energy transmission optical fiber |
| JPH10139472A (en) * | 1996-11-06 | 1998-05-26 | Nippon Sheet Glass Co Ltd | Glass composition for clad of refractive index distribution type optical element having core/clad structure |
| JPH10293226A (en) * | 1997-04-21 | 1998-11-04 | Yasuhiro Koike | Multimodal optical fiber |
| KR20010083495A (en) * | 2000-02-15 | 2001-09-01 | 김효근 | Optical fiber with a cladding having an outwardly graded index and fiber-optic filter using the same |
-
2014
- 2014-11-10 CN CN201410626272.2A patent/CN104635296A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4893896A (en) * | 1987-07-10 | 1990-01-16 | Mitsubishi Cable Industries, Ltd. | Energy transmission optical fiber |
| JPH10139472A (en) * | 1996-11-06 | 1998-05-26 | Nippon Sheet Glass Co Ltd | Glass composition for clad of refractive index distribution type optical element having core/clad structure |
| JPH10293226A (en) * | 1997-04-21 | 1998-11-04 | Yasuhiro Koike | Multimodal optical fiber |
| KR20010083495A (en) * | 2000-02-15 | 2001-09-01 | 김효근 | Optical fiber with a cladding having an outwardly graded index and fiber-optic filter using the same |
Non-Patent Citations (1)
| Title |
|---|
| 彭江得: "《光电子技术基础》", 30 June 1988 * |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110073257A (en) * | 2016-07-29 | 2019-07-30 | 康宁股份有限公司 | Low-loss single-mode optical fiber with chlorine doped core |
| CN106443871A (en) * | 2016-09-27 | 2017-02-22 | 南京鸿照科技有限公司 | Method for changing numerical aperture of plastic fiber |
| CN110224754A (en) * | 2018-03-02 | 2019-09-10 | 韩国光技术院 | Optical communication system |
| CN110224754B (en) * | 2018-03-02 | 2022-01-21 | 韩国光技术院 | Optical communication system |
| CN112099130A (en) * | 2020-09-25 | 2020-12-18 | 东北大学 | Slope-type refractive index distribution multi-core optical fiber with low crosstalk between cores |
| CN114839714A (en) * | 2022-04-27 | 2022-08-02 | 南京邮电大学 | Temperature-tunable ultra-negative dispersion twin-core photonic crystal fiber |
| CN117111206A (en) * | 2023-10-23 | 2023-11-24 | 武汉市飞瓴光电科技有限公司 | High non-linear quartz optical fiber |
| CN117111206B (en) * | 2023-10-23 | 2024-01-30 | 武汉市飞瓴光电科技有限公司 | High non-linear quartz optical fiber |
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