GB1593488A - Low loss high n a plastic clad optical fibres - Google Patents
Low loss high n a plastic clad optical fibres Download PDFInfo
- Publication number
- GB1593488A GB1593488A GB16250/78A GB1625078A GB1593488A GB 1593488 A GB1593488 A GB 1593488A GB 16250/78 A GB16250/78 A GB 16250/78A GB 1625078 A GB1625078 A GB 1625078A GB 1593488 A GB1593488 A GB 1593488A
- Authority
- GB
- United Kingdom
- Prior art keywords
- core
- silica
- optical fibre
- germania
- cladding
- 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.)
- Expired
Links
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
- G02B6/02033—Core or cladding made from organic material, e.g. polymeric material
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
- C03B37/014—Manufacture 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]
- C03B37/018—Manufacture 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] by glass deposition on a glass substrate, e.g. by inside-, modified-, plasma-, or plasma modified- chemical vapour deposition [ICVD, MCVD, PCVD, PMCVD], i.e. by thin layer coating on the inside or outside of a glass tube or on a glass rod
- C03B37/01807—Reactant delivery systems, e.g. reactant deposition burners
- C03B37/01815—Reactant deposition burners or deposition heating means
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
- C03B37/014—Manufacture 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]
- C03B37/018—Manufacture 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] by glass deposition on a glass substrate, e.g. by inside-, modified-, plasma-, or plasma modified- chemical vapour deposition [ICVD, MCVD, PCVD, PMCVD], i.e. by thin layer coating on the inside or outside of a glass tube or on a glass rod
- C03B37/01884—Means for supporting, rotating and translating tubes or rods being formed, e.g. lathes
- C03B37/01892—Deposition substrates, e.g. tubes, mandrels
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL 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
- C03C25/00—Surface treatment of fibres or filaments made from glass, minerals or slags
- C03C25/10—Coating
- C03C25/104—Coating to obtain optical fibres
- C03C25/105—Organic claddings
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2201/00—Type of glass produced
- C03B2201/06—Doped silica-based glasses
- C03B2201/20—Doped silica-based glasses doped with non-metals other than boron or fluorine
- C03B2201/28—Doped silica-based glasses doped with non-metals other than boron or fluorine doped with phosphorus
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2201/00—Type of glass produced
- C03B2201/06—Doped silica-based glasses
- C03B2201/30—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi
- C03B2201/31—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi doped with germanium
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2201/00—Type of glass produced
- C03B2201/06—Doped silica-based glasses
- C03B2201/30—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi
- C03B2201/40—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi doped with transition metals other than rare earth metals, e.g. Zr, Nb, Ta or Zn
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2201/00—Type of glass produced
- C03B2201/06—Doped silica-based glasses
- C03B2201/30—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi
- C03B2201/40—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi doped with transition metals other than rare earth metals, e.g. Zr, Nb, Ta or Zn
- C03B2201/42—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi doped with transition metals other than rare earth metals, e.g. Zr, Nb, Ta or Zn doped with titanium
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2201/00—Type of glass produced
- C03B2201/60—Silica-free oxide glasses
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2201/00—Type of glass produced
- C03B2201/60—Silica-free oxide glasses
- C03B2201/70—Silica-free oxide glasses containing phosphorus
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2201/00—Type of glass produced
- C03B2201/60—Silica-free oxide glasses
- C03B2201/78—Silica-free oxide glasses containing germanium
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2203/00—Fibre product details, e.g. structure, shape
- C03B2203/10—Internal structure or shape details
- C03B2203/22—Radial profile of refractive index, composition or softening point
- C03B2203/26—Parabolic or graded index [GRIN] core profile
Description
(54) LOW LOSS HIGH N.A. PLASTIC CLAD
OPTICAL FIBRES
(71) We INTERNATIONAL
STANDARD ELECTRIC COR
PORATION a Corpqration organised and existing under the Laws of the State of
Delaware, United States of America, of 320
Park Avenue, New York 22, State of New
York, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to low-loss optical fibres.
The numerical aperture of an optical fibre is generally designated as the sine of half of the acceptance angle of a coated fibre. When n1 is the refractive index of the fibre core and nO is that of the cladding the numerical aperture, (N.A.) equals (n12-n02)1=Sin fl. The larger the value of the effective N.A., therefore the larger the amount of light that enters the fibre. Since the numerical aperture is related to the difference between the refractive indices of the core and the cladding, attempts have been made to increase the difference by continuously increasing the refractive index of the core and decreasing that of the cladding.
With glass-on-glass optical fibres, the purest optical fibres are obtained by doping silica with a higher refractive index material to increase the refractive index of the core and either using silica per se, or silica with an added material to decrease the refractive index of the silica, for a cladding layer. The N.A. for glass-on-glass optical fibres is limited by the amount of refractive index increasing material that can be added to the silica before the thermal expansion properties of the overall fibre become substantially affected. When too much index raising material is added to the silica, the thermal coefficient of expansion of the doped core increases to a point where a mismatch occurs between the doped core and the undoped cladding. The differential thermal expansion between the highly doped silica core and the undoped silica cladding causes the preform to shatter upon cooling. Hence the amount of dopant that can be added to the core material to increase the N.A. is limited by the thermal expansion differential between the core material and the cladding. Attempts to decrease the refractive index of the cladding by adding dopants to lower the refractive index cause a thermal mismatch between the cladding materials and the silica substrate when the cladding is doped beyond a certain limited amount.
An object of this invention is to provide an optical fibre having a highly doped silica core and a high N.A. without causing a thermal mismatch between the optical fibre core and the optical fibre cladding.
According to the present invention, there is provided a high purity optical fibre having a large numerical aperture comprising a core of a doped silica material having a refractive index of at least 1.50, and a cladding layer surrounding said core consisting of a silicone resin material having a refractive index less than 1.50.
According to the present invention, there is further provided a method of making a high purity optical fibre which includes passing a mixture of gaseous germanium chloride and silicon tetrachloride through a tubular carbon mandrel while the gases are subjected to heating, in the presence of a free-oxygen-containing gas the proportion of germanium chloride to silicon tetrachloride in said gas flow being determined by the doping ratio required in the final product, so that a chemical vapour deposition process takes place to deposit a layer of germania silicate glass on the inner surface of the carbon cylinder, removing the carbon cylinder, e.g. by heat which renders it incandescent, so as to leave a germania silicate glass preform, drawing said preform to produce a fibre of said glass, and applying to said fibre a cladding of a dimethyl siloxane based silicone resin material.
The use of the resin, and especially the
use of a silicone resin, as a cladding for a
heavily-doped, high purity core, especially
of silica, formed by the chemical vapour
deposition (CVD) process overcomes the
shattering difficulty referred to above.
Embodiments of the invention will now
be described with reference to the
accompanying drawings, in which:
Figure 1 is a graphic representation of
the variation in N.A. with the difference in
refractive indices between the core and
cladding of an optical fibre;
Figure 2 is a graphic representation of
the variation in refractive index with
increasing germania content in the fibre
core;
Figure 3 is a graphic representation of the variation of the refractive index with increasing boron oxide content in the fibre
core;
Figure 4 is a perspective view of a disposable mold for forming the core material for the fibre of this invention
Figure 5 is a perspective view of the mold of Figure 4 containing the high purity core material for the fibre of this invention;
Figure 6 is a sectional view of a glass lathe for use with the mold of Figure 5;
Figure 6a is a cross-section of the material taken from the mold of Figure 5;
Figure 7 is a cross-section of the material of Figure 6a in solid form; and
Figure 7a is a cross-section of the material of Figure 7 after drawing into an optical fibre.
Doped silica core optical fibres have been made by the method of chemical vapour deposition with increasing concentrations of dopant to determine the highest possible N.A. attainable by standard methods of fibre manufacture.
The fibres were made by depositing increasing amounts of germania silicate on the inner surface of a silica substrate; collapsing the coated substrate and drawing the resultant preform into an optical fibre.
Since the theoretical value of refractive index for pure germania approaches 1.60 the germania silicate composition was enriched in germania for a series of optical fibres to determine the practical limit in refractive index attainable. By careful heating and annealing, optical fibres containing doped germania silicate cores and silica claddings with N.A. values of approximately 0.24 have been made. The refractive index of the doped silica core for these fibres measured approximately 1.50 and refractive index of the cladding measured approximately 1.46. As shown in
Figure 1, the N.A. is proportional to the difference between the refractive indices of the core (n,) and cladding (nO) respectively.
Due to the differences in thermal properties of the doped silica with increasing germania content, the refractive index for the dqped core reached approximately 1.50 before the differential expansion properties caused the preform to shatter upon cooling after the deposition process.The published relationship involving the index of refraction of germania doped silica is shown in Figure 2.
The theoretical value of 1.60 for nearly pure germania is unattainable with silica since the clad optical fibre's thermal expansion characteristics adversely affect the drawn fibre when the concentration of dopant reaches approximately 20 to 40% germania.
Since the N.A. is proportional to the difference in the refractive indices of the core and cladding, various attempts were made to decrease the refractive index of the cladding. Figure 3 shows the published relation between the refractive index of doped silica and increasing quantities of boron oxide.
The index of refraction for silica doped with increasing quantities of boron oxide is shown to decrease with the addition of a small amount of boron oxide and to increase for larger concentrations.
Cladding materials have been attained by doping silica with boron oxide to achieve an index of refraction of as low as 1.45. Using a germania doped silica core having a refractive index of 1.50 and a cladding consisting of silica doped with boron oxide and having a refractive index of 1.45 resulted in an optical fibre whose measured value of N.A. is 0.36. Attempts to raise the
N.A. value of doped core and doped cladding fibres beyond 0.40 have not heretofore been continuously successful.
Very carefully controlled deposition techniques and careful handling of the uncollapsed preforms resulted in slight increases in N.A. values in excess of 0.36 but the degree of control involved in the coating and annealing procedures make further increases in N.A. prohibitively expensive.
To increase the N.A. beyond that for the doped silica core other materials having a refractive index of less than 1.45 were investigated for use as a cladding material.
One material with a refractive index of approximately 1.41 that did not interfere with the expansion properties of the doped silica core was a highly purified silicone resin having the generic structure of dimethyl siloxane. The resin material provided high clarity for optical transmission, plus good adherence to the doped silica core material without thermal expansion mismatch with the doped silica core. Coating the doped silica core materials with the highly purified silicone resin resulted in optical fibres having N.A.
values of 0.43 with stable physical properties upon cooling.
The high concentration of pure germania silicate glass was provided by chemical vapour deposition of silica and germania materials within the inner confines of a silica tube. The tube containing an interior coating of germania silicate glass was then heated to a collapsing temperature to form a solid cylinder having a high germania silicate interior surrounded by a cladding of pure silica provided by the tube. The outer silica was then removed by grinding away the silica until only the inner germania silicate glass remained. The germania silicate cylinder was then mounted in a glass fibre processing tower and heated and drawn into an optical fibre. During the drawing, the fibre was directed through a container of high purity dimethyl siloxane resin to coat the exterior surface of the fibre with a continuous layer of silicone. The amount of germania in the germanium silicate glass was limited solely by the differential thermal properties between the doped silica core materials and the silica tubing after the deposition.
Highly doped silica preforms can be made by depositing high purity glass from the vapour phase using a plasma or oxyhydrogen torch. The glass can be grown as a form of boule, which is then drawn into a fibre and coated with silicone resin.
Higher doped silica glasses can readily be obtained by chemical vapour deposition within a disposable carbon cylinder and heating the deposited glass to consolidate it into a solid form. The carbon container can be removed by heating the carbon to its incandescence temperature in air and burning away the carbon so that no thermal mismatch occurs upon cooling. Since the high germania content glass no longer has to rely on a silica cladding layer for optical guiding properties, the thermal mismatch problems between germania doped silica and silica per se no longer exist. High germania containing glasses can be fabricated within the disposable carbon cylinder and the silicone cladding material can subsequently be applied without in any way affecting the properties of the glass.
The provision of a disposable carbon deposition substrate allows high germania glasses to be manufactured such that the theoretically attainable values as high as 1.6 in refractive index, as shown in Figure 2, may be attainable since thermal mismatch between the cladding and core materials no longer exist. The silicone material has excellent flexibility and readily adheres to the exterior surface of high germaniacontaining glasses without causing the glass to become fractured.
By the use of a disposable carbon mandrel as a deposition substrate for core materials, concentrations of germania are attainable in excess of 70% germania, giving a refractive index of approximately 1.55.
Using the silicone resin material as an outer cladding layer would thus result in N.A.
values in excess of 0.60.
For certain short-haul application where the fibre strength does not have to be exceptionally high, an optical fibre having pure germania core material and a silicone cladding could result in effective N.A.
values in excess of 0.80. The short lengths of high N.A. fibres could also be used to couple from light emitting diodes into long haul optical fibres having smaller values of
N.A. Other materials that can be used per se to form high refractive index cores are the fused oxides of zinc, phosphorus, titanium, aluminium, and zirconium. These materials can also be used in high concentrations with silica to form their respective glasses.
A disposable carbon substrate 13 for depositing high doped silica core materials is shown in Figure 4. The carbon substrate
13 is loaded in the glass lathe 19 of Figure 6 within a special water cooled cylinder 10 having a water inlet 2 and outlet 3 to ensure that the cylinder 10 does not become heated during the deposition process.
Heating is provided by the radio frequency coil 15 surrounding the water cooled silica jacket 10. The carbon cylinder 13 is loaded within the lathe 19 such that a space remains between the inner surface of the water cooled jacket 10 and the outer surface of the carbon substrate 13 for providing a steady flow of inert gas by means of intake nozzles 24 and 24'. The presence of the inert gas atmosphere prevents the carbon substrate 13 from becoming heated and oxidized during the vapour deposition process. The chemical vapour deposition materials are introduced into the carbon cylinder 13 by the cylinder end 20 and by intake tube 21 which carries
the requisite germanium chloride and
silicon tetrachloride gases along with the
necessary amount of oxygen. The chemical
vapour deposition reaction occurs in the
usual manner wherein the gaseous products
become heated under the influence of the
R.F. field and become deposited as
germania silicate glass upon the inner
surface of the cylinder 13.
The coated cylinder 13 is shown in Figure
5 after a layer of germania silicate glass 11
has been deposited upon the inner surface.
The carbon substrate 13 is removed after deposition' by shutting off the flow of inert gas and heating and allowing the carbon cylinder to become heated to incandescence in air. The remaining germania silicate glass shown in Figure 6a is then allowed to become heated to collapse into a solid rod as shown in Figure 7. The rod of solid germania silicate glass 11 is then placed in a drawing tower and is heated and drawn into an optical fibre core.
The optical fibre core 11 is then provided with a pure silicone resin cladding 12 to form a completed optical communication fibre 14 having an optical core 11 and an outer cladding 12.
Although optical communications fibres having large values of numerical aperture, are disclosed for optical communication purposes. This is by way of example only.
The glass fibres having high N.A. values readily provide application wherever such fibres should be employed.
WHAT WE CLAIM IS:
1. A high purity optical fibre having a large numerical aperture comprising a core of a doped silica material having a refractive index of at least 1.50 and a cladding layer surrounding said core consisting of a silicone resin material having a refractive index less than 1.50.
2. An optical fibre as claimed in claim 1 wherein the silica is doped with a material selected from the group consisting of germania, phosphorus oxide, titania, zinc oxide and alumina.
3. An optical fibre as claimed in claim I or 2, wherein the cladding material has dimethyl siloxane as the backbone of the cladding polymer.
4. An optical fibre as claimed in claim 1, 2 or 3, wherein the core has a graded index profile.
5. A method for forming high purity optical fibres having a large numerical aperture, including the steps of doping silica with a material having a higher refractive index than the silica to provide a fibre optic core material, drawing the doped silica material into an optical fibre, and coating the doped optical fibre with a silicone resin having an index of refraction lower than that of silica.
6. A method us claimed in claim 5, wherein the steps of doping the silica comprise depositing germania and silica on a substrate and collapsing the resulting germania-silicate glass tube to form a solid preform.
7. A method as claimed in claim 5, wherein the doping material is selected from the group consisting of the oxides of germanium, phosphorus, titanium, zinc and aluminium.
8. A method of making a high purity optical fibre which includes passing a mixture of gaseous germanium chloride and silicon tetrachloride through a tubular carbon mandrel while the gases are subjected to heating, in the presence of the free oxygen-containing gas, the proportion of germanium chloride to silicon tetrachloride in said gas flow being determined by the doping ratio required in the final product, so that a chemical vapour deposition process takes place to deposit a layer of germania silicate glass on the inner surface of the carbon cylinder, removing the carbon cylinder, e.g. by heating in air which renders it incandescent, so as to leave a germania silicate glass preform, drawing said preform to produce a fibre of said glass, and applying to said fibre a cladding of a dimethyl siloxane based silicone resin material.
9. A method as claimed in claim 8, wherein the heating to which said gases are subjected is effected by radio frequency heating while the carbon cylinder is cooled by an inert gas flow over its outer surface, and wherein to cause said incandescence of the cylinder the inert gas flow is cut off so that the cylinder is heated from the glass layer deposited thereon.
10. A high purity optical fibre having a large numerical aperture, which includes a core of a glass material having a refractive index of at least 1.50, said glass core being heavily doped silica and having been prepared by a chemical vapour deposition process, and a cladding of a silicone resin material having a refractive index less than 1.50.
11. An optical fibre as claimed in claim 10 in which the dopant used for the silica core is germania, and wherein the silicone resin material has the generic structure of dimethyl siloxane.
12. An optical fibre as claimed in claim 10 or 11, and wherein the core has a graded index profile.
13. An optical fibre substantially as described with reference to the accompanying drawings.
14. A method of making an optical fibre substantially as described with reference to the accompanying drawings.
Reference has been directed in pursuance of section 9, subsection (1) of the
Patents Act 1949, to patent No. 1,152,953.
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (14)
1. A high purity optical fibre having a large numerical aperture comprising a core of a doped silica material having a refractive index of at least 1.50 and a cladding layer surrounding said core consisting of a silicone resin material having a refractive index less than 1.50.
2. An optical fibre as claimed in claim 1 wherein the silica is doped with a material selected from the group consisting of germania, phosphorus oxide, titania, zinc oxide and alumina.
3. An optical fibre as claimed in claim I or 2, wherein the cladding material has dimethyl siloxane as the backbone of the cladding polymer.
4. An optical fibre as claimed in claim 1, 2 or 3, wherein the core has a graded index profile.
5. A method for forming high purity optical fibres having a large numerical aperture, including the steps of doping silica with a material having a higher refractive index than the silica to provide a fibre optic core material, drawing the doped silica material into an optical fibre, and coating the doped optical fibre with a silicone resin having an index of refraction lower than that of silica.
6. A method us claimed in claim 5, wherein the steps of doping the silica comprise depositing germania and silica on a substrate and collapsing the resulting germania-silicate glass tube to form a solid preform.
7. A method as claimed in claim 5, wherein the doping material is selected from the group consisting of the oxides of germanium, phosphorus, titanium, zinc and aluminium.
8. A method of making a high purity optical fibre which includes passing a mixture of gaseous germanium chloride and silicon tetrachloride through a tubular carbon mandrel while the gases are subjected to heating, in the presence of the free oxygen-containing gas, the proportion of germanium chloride to silicon tetrachloride in said gas flow being determined by the doping ratio required in the final product, so that a chemical vapour deposition process takes place to deposit a layer of germania silicate glass on the inner surface of the carbon cylinder, removing the carbon cylinder, e.g. by heating in air which renders it incandescent, so as to leave a germania silicate glass preform, drawing said preform to produce a fibre of said glass, and applying to said fibre a cladding of a dimethyl siloxane based silicone resin material.
9. A method as claimed in claim 8, wherein the heating to which said gases are subjected is effected by radio frequency heating while the carbon cylinder is cooled by an inert gas flow over its outer surface, and wherein to cause said incandescence of the cylinder the inert gas flow is cut off so that the cylinder is heated from the glass layer deposited thereon.
10. A high purity optical fibre having a large numerical aperture, which includes a core of a glass material having a refractive index of at least 1.50, said glass core being heavily doped silica and having been prepared by a chemical vapour deposition process, and a cladding of a silicone resin material having a refractive index less than 1.50.
11. An optical fibre as claimed in claim 10 in which the dopant used for the silica core is germania, and wherein the silicone resin material has the generic structure of dimethyl siloxane.
12. An optical fibre as claimed in claim 10 or 11, and wherein the core has a graded index profile.
13. An optical fibre substantially as described with reference to the accompanying drawings.
14. A method of making an optical fibre substantially as described with reference to the accompanying drawings.
Reference has been directed in pursuance of section 9, subsection (1) of the
Patents Act 1949, to patent No. 1,152,953.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US79242377A | 1977-04-29 | 1977-04-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1593488A true GB1593488A (en) | 1981-07-15 |
Family
ID=25156848
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB16250/78A Expired GB1593488A (en) | 1977-04-29 | 1978-04-25 | Low loss high n a plastic clad optical fibres |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS53135655A (en) |
| AU (1) | AU3539778A (en) |
| DE (1) | DE2818152A1 (en) |
| FR (1) | FR2389146A1 (en) |
| GB (1) | GB1593488A (en) |
| NL (1) | NL7804448A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2118320A (en) * | 1982-04-09 | 1983-10-26 | Western Electric Co | Doped optical fiber |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS56117204A (en) * | 1980-02-21 | 1981-09-14 | Nippon Telegr & Teleph Corp <Ntt> | Manufacture of optical fiber |
| DE3304721A1 (en) * | 1983-02-11 | 1984-08-16 | Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt | METHOD FOR PRODUCING A PREFORM FOR LIGHTWAVE GUIDES |
| JPH0378714A (en) * | 1989-08-23 | 1991-04-03 | Fujikura Ltd | Coated fiber for power transmission |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL6706652A (en) * | 1965-07-07 | 1967-12-11 | ||
| DE1494872B2 (en) * | 1965-07-07 | 1971-04-29 | Jenaer Glaswerk Sdhott & Gen , 6500 Mainz | METHOD FOR MANUFACTURING LIGHT GUIDING SYSTEMS |
| US3711262A (en) * | 1970-05-11 | 1973-01-16 | Corning Glass Works | Method of producing optical waveguide fibers |
| JPS5326289B2 (en) * | 1972-05-30 | 1978-08-01 | ||
| JPS49131208A (en) * | 1973-04-23 | 1974-12-16 | ||
| US4360250A (en) * | 1974-05-31 | 1982-11-23 | National Research Development Corp. | Optical waveguides |
-
1978
- 1978-04-19 JP JP4543778A patent/JPS53135655A/en active Pending
- 1978-04-24 AU AU35397/78A patent/AU3539778A/en active Pending
- 1978-04-25 GB GB16250/78A patent/GB1593488A/en not_active Expired
- 1978-04-26 NL NL7804448A patent/NL7804448A/en not_active Application Discontinuation
- 1978-04-26 FR FR7812276A patent/FR2389146A1/en not_active Withdrawn
- 1978-04-26 DE DE19782818152 patent/DE2818152A1/en not_active Withdrawn
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2118320A (en) * | 1982-04-09 | 1983-10-26 | Western Electric Co | Doped optical fiber |
Also Published As
| Publication number | Publication date |
|---|---|
| NL7804448A (en) | 1978-10-31 |
| AU3539778A (en) | 1979-11-01 |
| FR2389146A1 (en) | 1978-11-24 |
| JPS53135655A (en) | 1978-11-27 |
| DE2818152A1 (en) | 1978-11-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PS | Patent sealed | ||
| 732 | Registration of transactions, instruments or events in the register (sect. 32/1977) | ||
| PCNP | Patent ceased through non-payment of renewal fee |