CA1066570A - Optical fibres - Google Patents
Optical fibresInfo
- Publication number
- CA1066570A CA1066570A CA314,701A CA314701A CA1066570A CA 1066570 A CA1066570 A CA 1066570A CA 314701 A CA314701 A CA 314701A CA 1066570 A CA1066570 A CA 1066570A
- Authority
- CA
- Canada
- Prior art keywords
- tube
- glass
- vapor
- reagents
- bore
- 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
- 230000003287 optical effect Effects 0.000 title description 4
- 239000011521 glass Substances 0.000 claims abstract description 50
- 239000003153 chemical reaction reagent Substances 0.000 claims abstract description 33
- 238000010438 heat treatment Methods 0.000 claims abstract description 22
- 238000005253 cladding Methods 0.000 claims abstract description 21
- 239000000835 fiber Substances 0.000 claims abstract description 13
- 238000007496 glass forming Methods 0.000 claims abstract 9
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 31
- 239000011248 coating agent Substances 0.000 claims description 27
- 238000000576 coating method Methods 0.000 claims description 27
- 238000006243 chemical reaction Methods 0.000 claims description 19
- 238000004519 manufacturing process Methods 0.000 claims description 12
- 239000000463 material Substances 0.000 claims description 11
- 239000013307 optical fiber Substances 0.000 claims description 11
- 239000000377 silicon dioxide Substances 0.000 claims description 11
- 238000000034 method Methods 0.000 claims description 9
- 238000000151 deposition Methods 0.000 claims description 8
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 7
- 239000001301 oxygen Substances 0.000 claims description 7
- 229910052760 oxygen Inorganic materials 0.000 claims description 7
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 claims description 5
- 229910001882 dioxygen Inorganic materials 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 5
- 239000010410 layer Substances 0.000 claims 23
- 230000005540 biological transmission Effects 0.000 claims 2
- 239000011247 coating layer Substances 0.000 claims 2
- 239000012792 core layer Substances 0.000 claims 2
- 230000001747 exhibiting effect Effects 0.000 claims 2
- 125000002887 hydroxy group Chemical group [H]O* 0.000 claims 2
- 238000009740 moulding (composite fabrication) Methods 0.000 claims 2
- 238000007789 sealing Methods 0.000 claims 2
- 239000007787 solid Substances 0.000 abstract description 4
- 230000009850 completed effect Effects 0.000 description 4
- 239000005350 fused silica glass Substances 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- VXEGSRKPIUDPQT-UHFFFAOYSA-N 4-[4-(4-methoxyphenyl)piperazin-1-yl]aniline Chemical compound C1=CC(OC)=CC=C1N1CCN(C=2C=CC(N)=CC=2)CC1 VXEGSRKPIUDPQT-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- 238000005137 deposition process Methods 0.000 description 2
- 235000012239 silicon dioxide Nutrition 0.000 description 2
- 239000005049 silicon tetrachloride Substances 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- XJDNKRIXUMDJCW-UHFFFAOYSA-J titanium tetrachloride Chemical compound Cl[Ti](Cl)(Cl)Cl XJDNKRIXUMDJCW-UHFFFAOYSA-J 0.000 description 2
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000005587 bubbling Effects 0.000 description 1
- 239000012159 carrier gas Substances 0.000 description 1
- 150000001805 chlorine compounds Chemical class 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
Landscapes
- Manufacture, Treatment Of Glass Fibers (AREA)
Abstract
Abstract of the Disclosure The bore of a glass tube is coated with a layer of cladding glass.
By introducing glass forming vapor reagents into the bore of the tube and heating the reagents with a heating excitor moving relative to the tube.
The reagents proximate the heating excitor are converted to glass on the inside of the tube. The relative movement between the tube and excitor causes the glass layer to be uniform. In usual practice, the layer of cladding glass will be of equal or higher refractive index than that of the tube. A second layer of core glass of higher refractive index than that of the first layer may be deposited on the first layer. The conted tube is drawn into a fibre while collapsing the bore to form a solid core that may be surrounded by cladding.
By introducing glass forming vapor reagents into the bore of the tube and heating the reagents with a heating excitor moving relative to the tube.
The reagents proximate the heating excitor are converted to glass on the inside of the tube. The relative movement between the tube and excitor causes the glass layer to be uniform. In usual practice, the layer of cladding glass will be of equal or higher refractive index than that of the tube. A second layer of core glass of higher refractive index than that of the first layer may be deposited on the first layer. The conted tube is drawn into a fibre while collapsing the bore to form a solid core that may be surrounded by cladding.
Description
~Q6 Ei57~
~8L~:~Yy~8 5_L~ _In~ention This application is a division oE appllcation 172,817~ filed May 31, 1973.
Field of the Invention mis invention relates to the manufacture of optical fibres and particularly to an improved m~thod of coatin~ the bore of a glass tube9 United States Patent No. 3,659,915 issued May 2~ 1972 describes a process for making optical fibres wherein a layer of doped fused silica is formed on the inside wall of a tube of pure fused silica and the composite structure is drawn to collapse the inner layer to for~ a solid core sur-rounded by pure fused silica. This process requires the use of a glass tube of high optical purity which is quite costly and the drawing step introduces undesired contamination.
Summary of the Invention Parent application 172,ôl7 relates to a method of making an optical fiber lncluding the steps of: heat treating the bore of a hollow silica glass tube under vaccuu~ to remove moisture and prevent formation of oxygen-hydro-gen compounds in the fiber; coating the heat treated bore with a first silica glass layer in a hydrogen-free atmosphere;coating a second silica layer on said first silica layer~ said second silica layer having a higher refractive index than said first silica layer; and collapsing said tube and coated bore to form a solid str~cture having a core and cladding layer, said core having ;
- a higher index of refraction than said cladding layer.
' According to the present inventiop there ls provdded a :ethod of ~ ~ .
: ~ .
~O~jt;57~3 making a coated tube suitable for drawing into an optical fiber including the steps of: depositing a core glass layer on the inside of a tube by introduc-ing g~ass ~orming vapor reagents into the bore of said tube; and heating said vapor reagents in said tube by means of a vapor reaction heating excitor mov-ing relative to said tube whereby the heated vapor reagents proximate the vapor reaction heating excitor are converted to glass on the inside of the tube, the relative movement between the tube and excitor causing a relatively uniform layer of glass to be deposited throughout the length of the tube to thereby form a coated tube.
The tube is not necessarily a self supporting structure but may take the form of a deposited layer lining the bore of another tube. Methods suit-able for depositing the glass layer include evaporation, radio frequency (r.f.) sputtering, and r.f. excited vapour reaction.
Brief Description of the Drawings In ~he accompanying drawings which illustrate two coated tubes and an exemplary embodiments of the present in~ention:
~igure 1 shows a structure of a known type having a single core glass coating;
Figure 2 depicts a twice coated tube before drawing into a fibre;
Figure 3 depicts apparatus for coating the bore of a tube.
Description of the_Preferred Embodiments Figure 1 depicts a structure of a known type produced by the deposi-tion of a layer 10 upon the bore of a hollow tube 11. The core of the com-pleted fibre is provided by the material of the deposited layer 10 while the cladding is provided by the material of the tube 11.
~ .
. . ~ : . . . .. . .
~--....... - , . . .. . .. .. - .;. - . - .. : . . , , : - . -.:. . ... :.. . .: . . .
, .. , . . , . , , . , .. :
- ~fà6~'70 Figure ? dcpicts a structure of the type produced according to the parent application. The bore of a ho~low silica glass tube 20, ~hich can be slightly impure and lossy, is lined with a first layer 21 of low absorption silica cladding glass and then a further layer 22 of doped silica core glass.
The core of the completed fibre is provided by the material of the second de-posited layer 22, while the inner and outer regions of the cladding are pro-vided respectively by the material of the first deposited layer 21 and the material of the tube 20. The tube is thus spaced from the core and is not in-volved to any extent in light propagation. The outer region of the cladding can safely be made ~ore lossy and of a less expensive glass than the other remainder of the fibre, but energy should not be coupled into it from the core. Therefore the outer tube refracti~e index is equal to or less than and no greater than that of the inner cladding. me refractive index of this in-ner cladding is in its turn, less than that of the core which is of a higher refractive index. It may be noted that the refractive index of an absorbing medium is strictly a complex quantity and that it is the real part of the refractive index of the tube 20 ~hich must be not greater than the refractive index of the layer ., .. ~ .. ....
." ' ' :
',: . , . . :
~0~i6570 21.
The manufacturing process can also be used to produce a succession o~ layers upon -the bore of a tube whose composition is chosen to produce a substantially quadratic grading of refract-ive index required in -the production of` a self-focusing multi-mode fibre. -~
In the manufacture of single mode fibre a dep~sited layer only 0.5~ thick may be required. This is within the known art of deposition of oxides without need for close matching of the expansion coefficients of the substrate and deposited layer glasses. More generally thicker layers are required, typically in the range 5 to lO~. in which case attention has to be paid to matching the various expansion coefficients. Suitable compositions can be selected from a wide range of known glasses, and in particular it is known that a variety of high silica content glasses can be adequately matched to a pure silica glass substrate.
A preferred manufacture for an optical fibre to carry GaAs laser radiation employs a silica tube 30, as shown in Figure 3, typically 7 mm external diameter with 1 mm wall thickness. The ~ ' 20 bore of the tube is flame polished and then vacuum baked to remove ~ ;
any traces of moisture. The presence of moisture may produce -OH groups in the completed fibre with their attendant undersi able absorption in the region of 0.9~ . After the tube has been ~ ~
baked it is placed so as to pass through the centre of an r.f. ~ ;
induction coil 31 and its ends are located in seals 32.
~'`'": ' The higher refractive index core glass coating generally ~ ;
first deposited upon the surface of the bore of the -tube is the product of a known r.f. vapour reaction process producing a silica glass containing a few percent titania. The chemical reagents for this process are silicon tetrachloride, titanium tetrachloride, and '~
4 `' 106ti570 oxygen. Both chlorides are liquids a-t roorn temperature, but are introduced to the reaction zone in vapour f'orm by bubbling dry nitrogen carrier gas through the liquid reagents maintained at constant temperature. The two liquid reagents are kept sep-arate, and two independent gas streams are used for the entrain-ment. This enables the relative proportions of the two vapours at the reaction zone readily to be controlled merely by altering the relative flow rates. In the bore of the tube 30 the two vapours become mixed with a supply of dry oxygen gas. The reaction does not proceed spontaneously at room temperatures but is promoted in the localized region of the r.f. excited glow discharge.
A uniform coating along the length of the bore of the tube is provided by progressive movement of the tube 30 through the coil 31 or by movement o~ the coil along the length of the tube.
Uniformity of the deposited layer may be enhanced by rotating the tube about its axis during the deposition process. A small recipro~
cating movement of the tube or coil in the axial direction may als~
be superimposed.
The drawing of the coated tube into a fibre in such a way as to collapse its bore is performed as a separate manufacturing step. The tip of the tube is introduced into a hot zone to soften it for pulling into a fibre. Surface tension alone will suffice to `;-convert the softened hollow tube into a solid structure, but may be assisted by maintaining the inside of the tube at a reduced pressure.
In the present case, where the quality of the initial silica tube is less pure, the supply of titanium tetrachloride vapour is shut off while a first cladding glass layer of pure silica of equal or higher refractive 65~
inde~ than the tube is deposited in situ. The deposition process is then repeated using both titanium and silicon tetrachloride vapours so as to produce a second doped silica layer of higher refractive index than that of the first layer and which will form the core of the completed fibre.
';
,.
. 6 ~ -. . --. : . : . . ~ ~ .. . . . - . .,
~8L~:~Yy~8 5_L~ _In~ention This application is a division oE appllcation 172,817~ filed May 31, 1973.
Field of the Invention mis invention relates to the manufacture of optical fibres and particularly to an improved m~thod of coatin~ the bore of a glass tube9 United States Patent No. 3,659,915 issued May 2~ 1972 describes a process for making optical fibres wherein a layer of doped fused silica is formed on the inside wall of a tube of pure fused silica and the composite structure is drawn to collapse the inner layer to for~ a solid core sur-rounded by pure fused silica. This process requires the use of a glass tube of high optical purity which is quite costly and the drawing step introduces undesired contamination.
Summary of the Invention Parent application 172,ôl7 relates to a method of making an optical fiber lncluding the steps of: heat treating the bore of a hollow silica glass tube under vaccuu~ to remove moisture and prevent formation of oxygen-hydro-gen compounds in the fiber; coating the heat treated bore with a first silica glass layer in a hydrogen-free atmosphere;coating a second silica layer on said first silica layer~ said second silica layer having a higher refractive index than said first silica layer; and collapsing said tube and coated bore to form a solid str~cture having a core and cladding layer, said core having ;
- a higher index of refraction than said cladding layer.
' According to the present inventiop there ls provdded a :ethod of ~ ~ .
: ~ .
~O~jt;57~3 making a coated tube suitable for drawing into an optical fiber including the steps of: depositing a core glass layer on the inside of a tube by introduc-ing g~ass ~orming vapor reagents into the bore of said tube; and heating said vapor reagents in said tube by means of a vapor reaction heating excitor mov-ing relative to said tube whereby the heated vapor reagents proximate the vapor reaction heating excitor are converted to glass on the inside of the tube, the relative movement between the tube and excitor causing a relatively uniform layer of glass to be deposited throughout the length of the tube to thereby form a coated tube.
The tube is not necessarily a self supporting structure but may take the form of a deposited layer lining the bore of another tube. Methods suit-able for depositing the glass layer include evaporation, radio frequency (r.f.) sputtering, and r.f. excited vapour reaction.
Brief Description of the Drawings In ~he accompanying drawings which illustrate two coated tubes and an exemplary embodiments of the present in~ention:
~igure 1 shows a structure of a known type having a single core glass coating;
Figure 2 depicts a twice coated tube before drawing into a fibre;
Figure 3 depicts apparatus for coating the bore of a tube.
Description of the_Preferred Embodiments Figure 1 depicts a structure of a known type produced by the deposi-tion of a layer 10 upon the bore of a hollow tube 11. The core of the com-pleted fibre is provided by the material of the deposited layer 10 while the cladding is provided by the material of the tube 11.
~ .
. . ~ : . . . .. . .
~--....... - , . . .. . .. .. - .;. - . - .. : . . , , : - . -.:. . ... :.. . .: . . .
, .. , . . , . , , . , .. :
- ~fà6~'70 Figure ? dcpicts a structure of the type produced according to the parent application. The bore of a ho~low silica glass tube 20, ~hich can be slightly impure and lossy, is lined with a first layer 21 of low absorption silica cladding glass and then a further layer 22 of doped silica core glass.
The core of the completed fibre is provided by the material of the second de-posited layer 22, while the inner and outer regions of the cladding are pro-vided respectively by the material of the first deposited layer 21 and the material of the tube 20. The tube is thus spaced from the core and is not in-volved to any extent in light propagation. The outer region of the cladding can safely be made ~ore lossy and of a less expensive glass than the other remainder of the fibre, but energy should not be coupled into it from the core. Therefore the outer tube refracti~e index is equal to or less than and no greater than that of the inner cladding. me refractive index of this in-ner cladding is in its turn, less than that of the core which is of a higher refractive index. It may be noted that the refractive index of an absorbing medium is strictly a complex quantity and that it is the real part of the refractive index of the tube 20 ~hich must be not greater than the refractive index of the layer ., .. ~ .. ....
." ' ' :
',: . , . . :
~0~i6570 21.
The manufacturing process can also be used to produce a succession o~ layers upon -the bore of a tube whose composition is chosen to produce a substantially quadratic grading of refract-ive index required in -the production of` a self-focusing multi-mode fibre. -~
In the manufacture of single mode fibre a dep~sited layer only 0.5~ thick may be required. This is within the known art of deposition of oxides without need for close matching of the expansion coefficients of the substrate and deposited layer glasses. More generally thicker layers are required, typically in the range 5 to lO~. in which case attention has to be paid to matching the various expansion coefficients. Suitable compositions can be selected from a wide range of known glasses, and in particular it is known that a variety of high silica content glasses can be adequately matched to a pure silica glass substrate.
A preferred manufacture for an optical fibre to carry GaAs laser radiation employs a silica tube 30, as shown in Figure 3, typically 7 mm external diameter with 1 mm wall thickness. The ~ ' 20 bore of the tube is flame polished and then vacuum baked to remove ~ ;
any traces of moisture. The presence of moisture may produce -OH groups in the completed fibre with their attendant undersi able absorption in the region of 0.9~ . After the tube has been ~ ~
baked it is placed so as to pass through the centre of an r.f. ~ ;
induction coil 31 and its ends are located in seals 32.
~'`'": ' The higher refractive index core glass coating generally ~ ;
first deposited upon the surface of the bore of the -tube is the product of a known r.f. vapour reaction process producing a silica glass containing a few percent titania. The chemical reagents for this process are silicon tetrachloride, titanium tetrachloride, and '~
4 `' 106ti570 oxygen. Both chlorides are liquids a-t roorn temperature, but are introduced to the reaction zone in vapour f'orm by bubbling dry nitrogen carrier gas through the liquid reagents maintained at constant temperature. The two liquid reagents are kept sep-arate, and two independent gas streams are used for the entrain-ment. This enables the relative proportions of the two vapours at the reaction zone readily to be controlled merely by altering the relative flow rates. In the bore of the tube 30 the two vapours become mixed with a supply of dry oxygen gas. The reaction does not proceed spontaneously at room temperatures but is promoted in the localized region of the r.f. excited glow discharge.
A uniform coating along the length of the bore of the tube is provided by progressive movement of the tube 30 through the coil 31 or by movement o~ the coil along the length of the tube.
Uniformity of the deposited layer may be enhanced by rotating the tube about its axis during the deposition process. A small recipro~
cating movement of the tube or coil in the axial direction may als~
be superimposed.
The drawing of the coated tube into a fibre in such a way as to collapse its bore is performed as a separate manufacturing step. The tip of the tube is introduced into a hot zone to soften it for pulling into a fibre. Surface tension alone will suffice to `;-convert the softened hollow tube into a solid structure, but may be assisted by maintaining the inside of the tube at a reduced pressure.
In the present case, where the quality of the initial silica tube is less pure, the supply of titanium tetrachloride vapour is shut off while a first cladding glass layer of pure silica of equal or higher refractive 65~
inde~ than the tube is deposited in situ. The deposition process is then repeated using both titanium and silicon tetrachloride vapours so as to produce a second doped silica layer of higher refractive index than that of the first layer and which will form the core of the completed fibre.
';
,.
. 6 ~ -. . --. : . : . . ~ ~ .. . . . - . .,
Claims (9)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a method of making a coated tube suitable for drawing into an optical fiber by sequentially coating the base of the tube with at least two glass layers, the steps of: depositing at least one of the glass layers on the inside of the tube by introducing glass forming vapor reagents into the bore of said tube; and heating said vapor reagents in said tube by means of a vapor reaction heating excitor moving relative to said tube whereby the heated vapor reagents proximate the vapor reaction heating excitor are con-verted to glass on the inside of the tube, the relative movement between the tube and excitor causing a relatively uniform layer of glass to be deposited throughout the length of the tube to thereby form a coated tube.
2. The method of making an optical fiber preform which is substant-ially free of OH radicals whose presence attenuates light wave transmission therethrough at certain frequencies including the steps of: selecting a silica tube having a first index of refraction; heat treating the bore of said tube to remove from said bore substantially all traces of moisture;
sealing said tube at the ends thereof to exclude therefrom substantially all moisture and, throughout the remaining steps hereof, maintaining said bore free of OH groups; introducing into the sealed bore of said tube a first coating material in the form of flowing dry oxygen gas and glass form-ing reagents in unreacted vapor form; generating a moving hot zone by moving a vapor reaction heat excitor relative to the tube containing the flowing vapor so as to raise the temperature of said reagents sufficiently to cause said vapors to react to as to be transformed directly from a vapor state to a glass state to deposit and form a first glass coating, having an index of refraction equal to or higher than that of the tube upon said bore so as to form a cladding layer; rotating said tube during the above step to uniform coat said bore with said first glass coating; introducing into the sealed bore of said tube a second coating material in the form of flowing dry oxy-gen gas and glass forming reagents in unreacted vapor form different in com-position from said first coating material and mixing said oxygen and reagents forming a core glass coating on said cladding layer by heating said oxygen and reagents, with the moving vapor reaction heat excitor, to a temperature sufficiently high to cause said oxygen and reagents to react so as to be transformed directly from the vapor state to deposit and form a second glass coating or core upon said cladding layer, said core coating exhibiting an index of refraction that is higher than the index of refraction of said cladding layer; rotating said tube during the core glass coating step to uniformly coat said core layer on said clad layer to thereby form an opti-cal fibre preform.
sealing said tube at the ends thereof to exclude therefrom substantially all moisture and, throughout the remaining steps hereof, maintaining said bore free of OH groups; introducing into the sealed bore of said tube a first coating material in the form of flowing dry oxygen gas and glass form-ing reagents in unreacted vapor form; generating a moving hot zone by moving a vapor reaction heat excitor relative to the tube containing the flowing vapor so as to raise the temperature of said reagents sufficiently to cause said vapors to react to as to be transformed directly from a vapor state to a glass state to deposit and form a first glass coating, having an index of refraction equal to or higher than that of the tube upon said bore so as to form a cladding layer; rotating said tube during the above step to uniform coat said bore with said first glass coating; introducing into the sealed bore of said tube a second coating material in the form of flowing dry oxy-gen gas and glass forming reagents in unreacted vapor form different in com-position from said first coating material and mixing said oxygen and reagents forming a core glass coating on said cladding layer by heating said oxygen and reagents, with the moving vapor reaction heat excitor, to a temperature sufficiently high to cause said oxygen and reagents to react so as to be transformed directly from the vapor state to deposit and form a second glass coating or core upon said cladding layer, said core coating exhibiting an index of refraction that is higher than the index of refraction of said cladding layer; rotating said tube during the core glass coating step to uniformly coat said core layer on said clad layer to thereby form an opti-cal fibre preform.
3. A method according to claim 1 or 2 wherein the heating excitor is an r.f. coil.
4. A method of making a coated tube suitable for drawing into an optical fiber including the steps of: depositing a core glass layer on the inside of a tube by introducing glass forming vapor reagents into the bore of said tubes and heating said vapor reagents in said tube by means of a vapor reaction heating excitor moving relative to said tube whereby the heated vapor reagents proximate the vapor reaction heating excitor are con-verted to glass on the inside of the tube, the relative movement between the tube and excitor causing a relatively uniform layer of glass to be deposited throughout the length of the tube to thereby form a coated tube.
5. A method according to claim 4 including: depositing a second glass layer on the inside of the first glass layer by introducing second glass forming vapor reagents into the bore of said tube; and heating said second vapor reagents in said tube by means of the vapor reaction heating excitor moving relative to said tube whereby the heated vapor reagents proximate the vapor reaction heating excitor are converted to a glass layer having a second refractive index deposited on the first glass layer.
6. A method of making a coated tube suitable for drawing into an optical fiber including the steps of: depositing a plurality of glass layers having different indices of refraction on the inside of a tube by sequen-tially introducing mixtures of glass forming vapor reagents, for producing glass of different indices of refraction from others into the bore of said tube; heating said vapor reagents in said tube as they are sequentially introduced into the tube by means of a vapor reaction heating excitor moving relative to said tube whereby each of the heated vapor reagents proximate the vapor reaction heating excitor are converted to a glass layer of one index of refraction on the inside of the tube, the relative movement between the tube and excitor causing a relatively uniform layer of glass throughout the length of the tube; sequentially building up layers of glass coating of different indices of refraction on the inside of the tube and each succeed-ing coating to produce a self-focusing, multi-mode fiber having a substant-ially quadratic grading.
7. A method according to claim 4, 5 or 6 including rotating said tube during the process of being coated whereby more uniform coating layers of glass are deposited on the inside of said tube.
8. The method of making an optical fiber from an optical fiber preform which is substantially free of OH radicals whose presence attenuates light wave transmission therethrough at certain frequencies including the steps of: selecting a silica tube having a first index of refraction; heat treating the bore of said tube to remove from said bore substantially all traces of moisture; sealing said tube at the ends thereof to exclude therefrom substantially all moisture and, throughout the remaining steps hereof, maintaining said bore free of OH groups; introducing into the sealed bore o-E
said tube a first coating material in the form of flowing dry oxygen gas and glass forming reagents in unreacted vapor form; gen-erating a moving hot zone by moving a vapor reaction heat excitor relative to the tube containing the flowing vapor so as to raise the temperature of said reagents sufficiently to cause said vapors to react so as to be transformed directly from a vapor state to a glass state to deposit and form a first glass coating, having an index of refraction equal to or higher than that of the tube upon said bore so as to form a cladding layer; rotating said tube during the above step to uniformly coat said bore with said first glass coating;
introducing into the sealed bore of said tube a second coating material in the form of flowing dry oxygen gas and glass forming reagents in unreacted vapor form different in composition from the said first coating material and mixing said oxygen and reagents;
forming a core glass coating on said cladding layer by heating said oxygen and reagents, with the moving vapor reaction heat excitor, to a temperature sufficiently high to cause said oxygen and rea-gents to react so as to be transformed directly from the vapor state to deposit and form a second glass coating or core upon said cladding layer, said core coating exhibiting an index of refraction that is higher than the index of refraction of said cladding layer; rotating said tube during the core glass coating step to uniformly coat said core layer on said clad layer;
subjecting the tip of said cladded and coated tube to a heat sufficient to soften it to collapse said bore having cladding and coating layers thereon to form a structure; and drawing said heated structure into an optical fiber
said tube a first coating material in the form of flowing dry oxygen gas and glass forming reagents in unreacted vapor form; gen-erating a moving hot zone by moving a vapor reaction heat excitor relative to the tube containing the flowing vapor so as to raise the temperature of said reagents sufficiently to cause said vapors to react so as to be transformed directly from a vapor state to a glass state to deposit and form a first glass coating, having an index of refraction equal to or higher than that of the tube upon said bore so as to form a cladding layer; rotating said tube during the above step to uniformly coat said bore with said first glass coating;
introducing into the sealed bore of said tube a second coating material in the form of flowing dry oxygen gas and glass forming reagents in unreacted vapor form different in composition from the said first coating material and mixing said oxygen and reagents;
forming a core glass coating on said cladding layer by heating said oxygen and reagents, with the moving vapor reaction heat excitor, to a temperature sufficiently high to cause said oxygen and rea-gents to react so as to be transformed directly from the vapor state to deposit and form a second glass coating or core upon said cladding layer, said core coating exhibiting an index of refraction that is higher than the index of refraction of said cladding layer; rotating said tube during the core glass coating step to uniformly coat said core layer on said clad layer;
subjecting the tip of said cladded and coated tube to a heat sufficient to soften it to collapse said bore having cladding and coating layers thereon to form a structure; and drawing said heated structure into an optical fiber
9. The method of claim 4 or 8 wherein the heating excitor is an r.f. coil.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA314,701A CA1066570A (en) | 1972-06-08 | 1978-10-30 | Optical fibres |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB2677072A GB1427327A (en) | 1972-06-08 | 1972-06-08 | Glass optical fibres |
| CA172,817A CA1054795A (en) | 1972-06-08 | 1973-05-31 | Optical fibres |
| CA314,701A CA1066570A (en) | 1972-06-08 | 1978-10-30 | Optical fibres |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1066570A true CA1066570A (en) | 1979-11-20 |
Family
ID=27162824
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA314,701A Expired CA1066570A (en) | 1972-06-08 | 1978-10-30 | Optical fibres |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1066570A (en) |
-
1978
- 1978-10-30 CA CA314,701A patent/CA1066570A/en not_active Expired
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