WO2002075393A1 - An optical fibre and a method for the manufacture of a preform for an optical fibre - Google Patents

An optical fibre and a method for the manufacture of a preform for an optical fibre Download PDF

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Publication number
WO2002075393A1
WO2002075393A1 PCT/FI2002/000222 FI0200222W WO02075393A1 WO 2002075393 A1 WO2002075393 A1 WO 2002075393A1 FI 0200222 W FI0200222 W FI 0200222W WO 02075393 A1 WO02075393 A1 WO 02075393A1
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WO
WIPO (PCT)
Prior art keywords
optical fibre
characterized
particles
part
cladding
Prior art date
Application number
PCT/FI2002/000222
Other languages
French (fr)
Inventor
Markku Rajala
Harri Valkonen
Simo Tammela
Original Assignee
Liekki Oy
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority to FI20010556 priority Critical
Priority to FI20010556A priority patent/FI20010556A/en
Application filed by Liekki Oy filed Critical Liekki Oy
Publication of WO2002075393A1 publication Critical patent/WO2002075393A1/en

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Classifications

    • CCHEMISTRY; METALLURGY
    • C03GLASS; MINERAL OR SLAG WOOL
    • C03CCHEMICAL COMPOSITION OF GLASSES, GLAZES, OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C25/00Surface treatment of fibres or filaments made from glass, minerals or slags
    • C03C25/10Coating
    • C03C25/104Coating to obtain optical fibres
    • CCHEMISTRY; METALLURGY
    • C03GLASS; MINERAL OR SLAG WOOL
    • C03BMANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01Manufacture of glass fibres or filaments
    • C03B37/012Manufacture of preforms for drawing fibres or filaments
    • C03B37/014Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
    • C03B37/01413Reactant delivery systems
    • CCHEMISTRY; METALLURGY
    • C03GLASS; MINERAL OR SLAG WOOL
    • C03CCHEMICAL COMPOSITION OF GLASSES, GLAZES, OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C25/00Surface treatment of fibres or filaments made from glass, minerals or slags
    • C03C25/10Coating
    • C03C25/465Coatings containing composite materials
    • C03C25/47Coatings containing composite materials containing particles, fibres or flakes, e.g. in a continuous phase
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B6/00Light guides
    • G02B6/02Optical fibre with cladding with or without a coating
    • G02B6/0229Optical fibre with cladding with or without a coating characterised by nanostructures, i.e. structures of size less than 100 nm, e.g. quantum dots
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B6/00Light guides
    • G02B6/02Optical fibre with cladding with or without a coating
    • G02B6/02295Microstructured optical fibre
    • CCHEMISTRY; METALLURGY
    • C03GLASS; MINERAL OR SLAG WOOL
    • C03BMANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2201/00Type of glass produced
    • C03B2201/06Doped silica-based glasses
    • CCHEMISTRY; METALLURGY
    • C03GLASS; MINERAL OR SLAG WOOL
    • C03BMANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2201/00Type of glass produced
    • C03B2201/06Doped silica-based glasses
    • C03B2201/30Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi
    • C03B2201/58Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi doped with metals in non-oxide form, e.g. CdSe
    • CCHEMISTRY; METALLURGY
    • C03GLASS; MINERAL OR SLAG WOOL
    • C03BMANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2203/00Fibre product details, e.g. structure, shape
    • C03B2203/10Internal structure or shape details
    • C03B2203/14Non-solid, i.e. hollow products, e.g. hollow clad or with core-clad interface
    • CCHEMISTRY; METALLURGY
    • C03GLASS; MINERAL OR SLAG WOOL
    • C03BMANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2203/00Fibre product details, e.g. structure, shape
    • C03B2203/42Photonic crystal fibres, e.g. fibres using the photonic bandgap PBG effect, microstructured or holey optical fibres

Abstract

The invention relates to an optical fibre consisting of at least a core part (11) and a cladding part (12), in which cladding partthere are single particles (42) whose refractive index deviates from the refractive index of the material of the cladding part, bymeans of which particles the variations in the refractive index that are necessary for the function of the optical fibre are implemented.

Description

An optical fibre and a method for the manufacture of a preform for an optical fibre

The invention relates to an optical fibre according to the preamble of claim 1 , and a method according to the preamble of claim 14 for the manufacture of a preform for an optical fibre.

Fiber optics is applied in a great variety of optical systems. Fiber optics has become especially significant in electric communication where a shift is taking place from conventional messages transmitted by electric current travelling in a conductor to messages transmitted in optical fibres by light impulses.

Fig. 1 shows in a simplified manner the operating principle of a con- ventional optical fiber by means of a cross-sectional view. In its simplest form the optical fibre 10 consists of an inner layer i.e. core 11 , and an outer layer surrounding the core, i.e. a cladding 12. If the refractive index of the cladding material is sufficiently smaller than the refractive index of the core in the wavelength area in use, the beam of light 13 travelling in the core experiences total reflection in the interface of the core and the cladding. As a result of this, the beam of light remains in the core and the optical fibre can be used for conveying light.

Fig. 2 shows a method disclosed in the US patent 5,802,236 for the manufacture of a so-called holey in a fibre. In the holey-fibre, the refractive index difference intended to be reached by the total reflection is attained with small pipes 21 placed around the centre of the fibre. In connection with the manufacturing process of the fibre, the diameter of the pipes is reduced to such a small scale in relation to the wavelength of the light to be used that the light travelling in the fibre does not "see" them as individual interfaces, but experiences them as changes in the refractive index. As a result of the small size of these so-called capillary holes, part of the light penetrates inside the capillary and this part of the light "sees" the refractive index of the material inside the capillary (for example air, wherein n = 1.0). By placing these pipes in the desired manner, it is possible to attain a variation in the refractive index similar to a conventional fibre, in which the cladding and the core are made of different materials. Thus, the beam of light travelling in the area 22 restricted by the pipes 21 experiences total reflection while experiencing the variation in the refractive index that is caused by the pipes. Thus, the holey-fibre functions as a light-conveying element similar to a con- ventional fibre.

Communication systems based on optical fibres contain numerous different fibre optical elements, and the requirements set for the same vary a great deal. The aim is, for example, to make the losses in the transmission fibres as small as possible. In practice, it will, however, never be possible to make the transmission fibres completely loss-free. Thus, when the optical signal is transferred long distances, the optical signal to be transferred can be typically amplified at fixed intervals. For this purpose, for example special optical amplifiers have been de- veloped, in which the signal is amplified by utilizing stimulated emission. In stimulated emission the incident light (photon) causes the discharge of the excited state in the medium, and the photon produced thereby is identical with the stimulating photon. The generally used optical fibre amplifiers utilize an optical fibre in which the core is doped with the necessary active medium, for example erbium oxide.

The active medium is typically brought to the excited state by conveying to the active optical fibre located in the amplifier a wavelength shorter than the signal wavelength, i.e. radiation with a greater amount of energy, obtained for example from a semiconductor laser. This so- called pump light adjusts a chemical element, or compound, typically erbium, added for this purpose in the core of the optically active fibre. The signal light that transmits information and travels in the core can cause the discharge of this excited state through stimulated emission. To attain the amplification, the travel paths of the pump and signal radiation must intersect, so that the signal radiation could discharge the excitation states caused by the pump radiation from the erbium atoms located in this area. Thus, one of the challenges in the manufacture of optical amplifiers is the coupling of the pump light obtained from the pump laser and the signal light advantageously and with a good efficiency in the same fibre without significant losses. The double-clad structure shown in Fig. 3 is one known method for coupling a pump beam to a fibre. In the double-clad structure an inner cladding layer 32 is produced around the core 31 of the fibre, said cladding layer functioning as a light channel for the pump beam. The size of the core is typically in the same order of magnitude with the light beam 34 to be amplified that travels in the core. (To clarify the operating idea of the fibre, the core 31 is in Fig. 3 drawn so that it is considerably larger in relation to the diameter of the fibre than in reality.) Outside the inner cladding there is an outer cladding 33. The refractive indices of the core 31 and the inner cladding 32 are selected in such a manner that the amplified signal 34 travelling in the core experiences a reflection in the first interface 35a as presented above. To put it simple, it can be said that the beam 34 to be amplified that travels in parallel with the fibre in the core 31 and is in the same order of mag- nitude with the core constantly experiences total reflections over the entire area of the interface 35a. In a corresponding manner, the refractive indices of the inner and outer cladding are selected in such a manner that the pump beam 36 travelling in the inner cladding experiences a total reflection from the interface 35b.

In an ideal situation, the structure of the cross-section of the double- clad fibre is not circularly symmetrical. Different designs of the pump light channel are disclosed for example in the US patent 5,533,163.

The manufacture of both the aforementioned fibres of prior art is difficult. In the manufacture of holey-fibres problems are caused by the fact that the dimensions of the pipes easily change in connection with the drawing of the fibre, and thus it is difficult to control the geometry of the fibre. If the pipe collapses at some point, the refractive index in said point is greater than that in the non-collapsed point. As a result of this, the desired total reflection does not occur in said point, and the radiation travelling in the core escapes to the cladding material, thus causing losses. The solution based on pipes does not function efficiently as a cladding structure of a multimode channel, because then the different modes can couple to leaking modes as a result of scattering and the reflecting uneven surface. It is difficult to manufacture the double-clad structure, because the differences in materials in different layers are typically implemented by doping different constituents that change the refractive index in the same basic material. Large dopant concentrations must be used to at- tain sufficient refractive index differences necessary for a functional double-clad structure. However, for example different refractive indices of dopants result in that stresses are produced in the fibre. To maintain a sufficiently small optical double refraction caused by the stresses in the fibre, these stresses must be as symmetrical as possible, and this, in turn, considerably restricts the use of other than circularly symmetrical structures in the cross-sections of the cladding layers.

In prior art, attempts have been made to solve the above-mentioned problems of the double-clad structure by using different polymers in the outer cladding layer, by means of which small refractive indices are attained when compared to pure silicon dioxide. Because the glass transition temperatures of polymers are low and they are reasonably elastic materials, they do not cause stresses to such an extent as conventional solutions. The mechanical strength of polymers are, however, significantly lower than the mechanical strength of glass typically used in the inner parts. This results in that the glass parts of the fibre are primarily responsible for the mechanical strength of the fibre. This, in turn, requires an unsymmetrical glass part (that thus forms the shape of the pump light channel). This hampers the geometrical optimization of the pump light channel.

It is an aim of the present invention to provide a novel light guide that eliminates the problems of prior art. The light guide according to the invention is characterized in what will be presented in the characterizing part of claim 1. The method according to the invention is characterized in what will be presented in the characterizing part of claim 14. Advantageous embodiments of the invention will be presented in the dependent claims.

It is easier to manufacture the light guide according to the invention than the holey optical fibre or prior art. In connection with the manufacture of an optical fibre preform the particles grown on the cladding part of the fibre do not lose their shape as easily as long tube-like structures. Since the grown particles are substantially smaller than the wavelength of light when seen in perpendicular to the propagation of light, the absence of single particles in the structure does not signifi- cantly affect the behaviour of light.

By means of the solution according to the invention it is easy to adjust the variations in the refractive index produced in the optical fibre either by varying the concentration of the particles or the diameter of the same in the direction of the radius of the fibre.

In the following, the invention will be described in detail with reference to the appended drawings, in which

Fig. 1 shows the operating principle of an optical fibre of prior art,

Fig. 2 shows the structure of a holey optical fibre of prior art,

Fig. 3 shows the basic structure of a double-clad optical fibre,

Fig. 4 shows the manufacturing process of an optical fibre according to an embodiment of the invention,

Fig. 5 shows a flow chart of a method according to an embodiment of the invention, and

Fig. 6 shows an embodiment of the light guide according to the invention.

Figs 1, 2 and 3 have been discussed above in connection with the de- scription of prior art.

It is a known fact that when the light meets a group of particles in which the size of the particles in relation to the wavelength of radiation is small, the radiation does not experience the object as single particles but as an optical change in the medium in such a manner that the optical properties of the particle group that are experienced by light are a combination of the original medium and the small particles added thereto. Naturally, this only applies in such a case where the optical properties of the particles differ from the refractive index of the medium. In the solution according to the invention, this fact has been utilized in order to produce the variation in the refractive index, necessary in the optical fibre.

Deviating from the solutions of prior art, the scattering objects are single particles in the solution according to the invention. In this context the term particle refers not only to conventional solid particles, but also to single objects, such as gas bubbles, produced of a gaseous or liquid medium. These particles can be produced in the fibre advantageously when the so-called preforms for the fibre are manufactured. In the act of drawing an optical fibre the preform of the fibre is passed at low speed to a fibre drawing furnace and it is drawn from the furnace at a considerably higher speed. Thus, the dimensions of the preform to be drawn are reduced, and the very thin glass bar produced thereby is thus called a fibre.

Fig. 4 shows a preferred embodiment of the method according to the invention. In the method the fibre preform 40 is manufactured by spraying a cladding part 47 around a core part 46 of the fibre by means of a flame spraying apparatus 41. The spraying apparatus can be for example a flame spraying apparatus described in the patent application WO0020346. By means of the apparatus it is possible to produce the basic material of the cladding part 47 and to attain the desired concentration of particles 42 with a desired diameter and composition in the material to be sprayed. To arrange the material to be sprayed in the desired manner around the core part 46, it is possible to advantageously change the spraying point for example by moving the spray 41 or by moving/rotating the preform 40.

In the solution described in Fig. 4, the cladding layer 47 is sprayed around a finished core part 46. The method according to the invention is not, however, restricted solely to the solution of the described kind, because the method can also be applied for example in cases where the core part is first produced by spraying and the cladding part is produced on top of the same by means of a second spraying. Thus, the solution according to the invention is not restricted to the spraying in the direction of the radius of the fibre preform according to Fig. 4. The spraying can also take place in the direction of the axis of the preform. This is a possible alternative for the manufacture the core part of the fibre, wherein there is no object in use around which the layer to be formed could be sprayed.

The flow chart of Fig. 5 shows by way of example the use of an embodiment of the method according to the invention for the manufacture of an optical fibre according to the invention. At the first stage 51 of the method, a core preform is produced for example by means of solution doping method or another method known as such. The core preform produced at stage 52 is formed into the desired shape. At stage 53, a layer containing particles is grown on top of the core preform with the desired shape for example by means of the above-described spraying or another outside vaporphase deposition (OVD) method. At stage 54, the layer containing particles is sintered to obtain the desired density. Thereafter the preform is formed into the desired shape at stage 55. In the case of a conventional fibre, the fibre is advantageously formed into an asymmetrical shape, but for example in the case of a double-clad fibre, it is advantageously possible to use other shapes as well.

At stage 56 the preform is positioned in a manner known as such inside a so-called sleeving pipe protecting the preform at the drawing stage, and the desired negative pressure is adjusted in the pipe. At the final stage of the process, the fibre is drawn, wherein optical fibre is drawn from the preform by advantageously adjusting the drawing tension, the drawing temperature and drawing speed. Thus, the sleeving pipe collapses on top of the centre of the fibre, thus forming the outer- most cladding part of the fibre.

All things considered, the method according to the invention is a very flexible method for producing optical fibres, because by means of the method it is possible to easily produce different kinds of layers in the optical fibre by varying not only the basic material to be sprayed, but also the concentration, diameter and material of the particles supplied in the material. By adjusting the size of the particles it is also possible to partly control the coupling of the optical modes propagating in the inner cladding layer to each other. This can be attained for example in such a manner that in the interface between the core and the cladding total reflection is controlled by means of one of the aforementioned methods in such a manner that the desired optical modes propagating in the core are coupled to each other in the desired manner. This is useful when an even distribution of the optical efficiency is desired in the multimode light channel.

Fig. 6 shows an embodiment of the optical fibre according to the invention. Inside the optical fibre 60, several successive layers have been produced in the same fibre preform for example by spraying with the above-described apparatus. By using the same basic material all the time, but varying the properties of particles in different layers, refractive index variations 61 have been produced in the fibre. The desired variations in the refractive index can be attained for example by increasing the concentration of the particles between different spraying occasions. If the basic material in use is glass and the particles, for example gas bubbles or polymer particles, have a smaller refractive index than glass, this results in that it is possible to produce interfaces in the fibre in which the refractive index changes in the desired manner. This enables the conveying of light in the fibre by means of total reflection.

In another preferred embodiment of the invention the desired refractive index variation is attained by varying the diameter of the particles when moving further apart from the core of the fibre. It is possible to implement a refractive index variation that is advantageous in view of the function of the fibre for example in such a manner that the particles located closer to the core of the fibre have a smaller diameter than the particles located further away from the core of the fibre. The most useful particle sizes vary between 0.001 and 0.5 micrometers.

When the above-described two advantageous embodiments are compared to the double-clad optical fibre solution of Fig. 3, it would mean that the first interface 35a could be formed either by using fewer or smaller particles when compared to the second interface 35b. A special advantage of the solution according to the invention is that the fibre preform and thus the cladding and core parts of the optical fibre formed of the fibre preform can be made of the same basic material. The advantage is especially emphasized for example in the manufacture of structures containing several layers that are used for example in optical amplification and are similar to the double-clad fibre, because by means of the solution according to the invention it is possible to concentrate more on the optimization of the geometry of the optical fibre for example in such a manner that the variation in the re- tractive index experienced by the radiation travelling in the cladding part is of such a quality that the pump radiation travels through the core part as often as possible.

Hereinabove, some embodiments of the method and optical fibre ac- cording to the invention have been described, but the invention is not restricted solely to these embodiments, but it can vary within the scope of the appended claims.

Claims

Claims:
1. An optical fibre consisting of at least a core part (11) and a cladding part (12), in which cladding part there are objects whose refractive in- dex deviates from the refractive index of the material of the cladding part, characterized in that said objects are single particles (42).
2. The optical fibre according to claim 1 , characterized in that the variation in the refractive index of the cladding material that is experi- enced by the radiation travelling in the cladding part is such that the direction of the radiation travelling in the cladding material changes as a result of variations in the refractive index in such a manner that the radiation travels through the core part more than once.
3. The optical fibre according to claim 1 , characterized in that the refractive index of the single particles (42) is smaller than the refractive index of the cladding material (47).
4. The optical fibre according to claim 1 , characterized in that the size of the single particles (42) is 0.001 to 0.5 micrometers.
5. The optical fibre according to claim 1 , characterized in that said particles (42) are gas bubbles.
6. The optical fibre according to claim 1 , characterized in that said particles (42) are polymer particles.
7. The optical fibre according to claim 1 , characterized in that said particles (42) are metal particles.
8. The optical fibre according to claim 1, characterized in that the diameter of said particles (42) is dimensioned in such a manner that in the total reflection between the core and the cladding a desired amount of coupling of light takes place between the different modes propagating in the core.
9. The optical fibre according to claim 1 , characterized in that the concentration of said particles (42) grows while moving further away from the core part of the fibre.
10. The optical fibre according to claim 1 , characterized in that the diameter of said particles (42) grows while moving further away from the core part of the fibre.
11. The optical fibre according to claim 1 , characterized in that the optical fibre is a fibre (30) with a double-clad structure.
12. The optical fibre according to claim 1, characterized in that the light guide layer surrounding the core part of the double-clad structure functions as said cladding part.
13. The optical fibre according to claim 1 , characterized in that the fibre is intended for optical amplification of the radiation travelling in the core part.
14. Method for the manufacture of a preform for an optical fibre containing at least a core part (11) and a cladding part (12), characterized in that the manufacturing process comprises a stage in which single particles (42) are produced in at least one part of the preform, said particles deviating from the refractive index of the material of said part.
15. The method according to claim 14, characterized in that the method comprises a stage in which the part to be manufactured is manufactured by spraying a material in an object.
16. The method according to claim 15, characterized in that said particles (42) are brought in said part in connection with spraying.
PCT/FI2002/000222 2001-03-19 2002-03-19 An optical fibre and a method for the manufacture of a preform for an optical fibre WO2002075393A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
FI20010556 2001-03-19
FI20010556A FI20010556A (en) 2001-03-19 2001-03-19 The optical fiber and a method for producing valokuituaihion

Publications (1)

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WO2002075393A1 true WO2002075393A1 (en) 2002-09-26

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Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1564569A1 (en) * 2004-02-12 2005-08-17 Samsung Electronics Co., Ltd. Porous optical fiber and method for manufacturing the same
WO2007055881A1 (en) * 2005-11-08 2007-05-18 Corning Incorporated Microstructured optical fiber and its manufacturing method
WO2008110668A1 (en) * 2007-03-15 2008-09-18 Liekki Oy Optical fiber structure and a method of producing thereof
US7433566B2 (en) 2006-06-30 2008-10-07 Corning Incorporated Low bend loss optical fiber with high modulus coating
WO2008140767A1 (en) 2007-05-08 2008-11-20 Corning Incorporated Method to produce microstructured optical fibers comprising voids
US7505660B2 (en) 2006-06-30 2009-03-17 Corning Incorporated Microstructured transmission optical fiber
US7526169B2 (en) 2006-11-29 2009-04-28 Corning Incorporated Low bend loss quasi-single-mode optical fiber and optical fiber line
US7567742B2 (en) 2003-10-30 2009-07-28 Virginia Tech Intellectual Properties, Inc. Holey optical fiber with random pattern of holes and method for making same
US7787731B2 (en) 2007-01-08 2010-08-31 Corning Incorporated Bend resistant multimode optical fiber
US7844154B2 (en) 2007-05-07 2010-11-30 Corning Incorporated Optical fiber for optical power transmission
US8175437B2 (en) 2008-02-07 2012-05-08 Corning Incorporated Microstructured transmission optical fiber
US8406592B2 (en) 2007-12-13 2013-03-26 Corning Incorporated Bend resistant multimode optical fiber
US9481599B2 (en) 2010-12-21 2016-11-01 Corning Incorporated Method of making a multimode optical fiber

Citations (4)

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Publication number Priority date Publication date Assignee Title
US5191206A (en) * 1991-04-16 1993-03-02 Electric Power Research Institute, Inc. Distributed fiber optic sensor using clad material light backscattering
EP0556580A1 (en) * 1992-02-21 1993-08-25 Corning Incorporated Method of doping porous glass preforms
US5778129A (en) * 1996-01-12 1998-07-07 Fujitsu Limited Doped optical fiber having core and clad structure for increasing the amplification band of an optical amplifier using the optical fiber
WO2000020346A1 (en) * 1998-10-05 2000-04-13 Liekki Oy Method and device for spraying of a material

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5191206A (en) * 1991-04-16 1993-03-02 Electric Power Research Institute, Inc. Distributed fiber optic sensor using clad material light backscattering
EP0556580A1 (en) * 1992-02-21 1993-08-25 Corning Incorporated Method of doping porous glass preforms
US5778129A (en) * 1996-01-12 1998-07-07 Fujitsu Limited Doped optical fiber having core and clad structure for increasing the amplification band of an optical amplifier using the optical fiber
WO2000020346A1 (en) * 1998-10-05 2000-04-13 Liekki Oy Method and device for spraying of a material

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8861912B2 (en) 2003-10-30 2014-10-14 Virginia Tech Intellectual Properties, Inc. Holey optical fiber with random pattern of holes and method for making same
US8983258B2 (en) 2003-10-30 2015-03-17 Virginia Tech Intellectual Properties, Inc. Holey optical fiber with random pattern of holes and method for making same
US7567742B2 (en) 2003-10-30 2009-07-28 Virginia Tech Intellectual Properties, Inc. Holey optical fiber with random pattern of holes and method for making same
US7286739B2 (en) 2004-02-12 2007-10-23 Samsung Electronics Co., Ltd. Porous optical fiber and method for manufacturing the same
EP1564569A1 (en) * 2004-02-12 2005-08-17 Samsung Electronics Co., Ltd. Porous optical fiber and method for manufacturing the same
WO2007055881A1 (en) * 2005-11-08 2007-05-18 Corning Incorporated Microstructured optical fiber and its manufacturing method
US7450806B2 (en) 2005-11-08 2008-11-11 Corning Incorporated Microstructured optical fibers and methods
US7930904B2 (en) 2005-11-08 2011-04-26 Corning Incorporated Method of making an optical fiber having voids
US7505660B2 (en) 2006-06-30 2009-03-17 Corning Incorporated Microstructured transmission optical fiber
US7433566B2 (en) 2006-06-30 2008-10-07 Corning Incorporated Low bend loss optical fiber with high modulus coating
US7526169B2 (en) 2006-11-29 2009-04-28 Corning Incorporated Low bend loss quasi-single-mode optical fiber and optical fiber line
US7787731B2 (en) 2007-01-08 2010-08-31 Corning Incorporated Bend resistant multimode optical fiber
WO2008110668A1 (en) * 2007-03-15 2008-09-18 Liekki Oy Optical fiber structure and a method of producing thereof
US8620126B2 (en) 2007-03-15 2013-12-31 Nlight Oy Optical fiber structure and a method of producing thereof
US7844154B2 (en) 2007-05-07 2010-11-30 Corning Incorporated Optical fiber for optical power transmission
US8464556B2 (en) 2007-05-08 2013-06-18 Corning Incorporated Microstructured optical fibers and methods
WO2008140767A1 (en) 2007-05-08 2008-11-20 Corning Incorporated Method to produce microstructured optical fibers comprising voids
US8406592B2 (en) 2007-12-13 2013-03-26 Corning Incorporated Bend resistant multimode optical fiber
US8474287B2 (en) 2008-02-07 2013-07-02 Corning Incorporated Microstructured transmission optical fiber
US8175437B2 (en) 2008-02-07 2012-05-08 Corning Incorporated Microstructured transmission optical fiber
US9481599B2 (en) 2010-12-21 2016-11-01 Corning Incorporated Method of making a multimode optical fiber

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FI20010556D0 (en)
FI20010556A (en) 2002-09-20

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