CA2157514A1 - Method of fabricating a preform for an amplifying optical waveguide, and an optical waveguide - Google Patents
Method of fabricating a preform for an amplifying optical waveguide, and an optical waveguideInfo
- Publication number
- CA2157514A1 CA2157514A1 CA002157514A CA2157514A CA2157514A1 CA 2157514 A1 CA2157514 A1 CA 2157514A1 CA 002157514 A CA002157514 A CA 002157514A CA 2157514 A CA2157514 A CA 2157514A CA 2157514 A1 CA2157514 A1 CA 2157514A1
- Authority
- CA
- Canada
- Prior art keywords
- optical waveguide
- core
- ndf3
- substrate
- prf3
- 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.)
- Abandoned
Links
Classifications
-
- 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
- C03C13/00—Fibre or filament compositions
- C03C13/04—Fibre optics, e.g. core and clad fibre compositions
- C03C13/045—Silica-containing oxide glass compositions
-
- 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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/06—Construction or shape of active medium
- H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
- H01S3/067—Fibre lasers
-
- 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
- C03B2201/34—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi doped with rare earth metals, i.e. with Sc, Y or lanthanides, e.g. for laser-amplifiers
- C03B2201/36—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi doped with rare earth metals, i.e. with Sc, Y or lanthanides, e.g. for laser-amplifiers doped with rare earth metals and aluminium, e.g. Er-Al co-doped
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Physics & Mathematics (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Optics & Photonics (AREA)
- Manufacturing & Machinery (AREA)
- Electromagnetism (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Plasma & Fusion (AREA)
- Lasers (AREA)
- Optical Integrated Circuits (AREA)
- Glass Compositions (AREA)
- Optical Fibers, Optical Fiber Cores, And Optical Fiber Bundles (AREA)
- Manufacture, Treatment Of Glass Fibers (AREA)
Abstract
There is a considerable need for optical fibre amplifiers for the wavelength range around 1300 nm for information transmission.
The basic material for the amplifier light guide (10) needed therefor is to be silicon dioxide. The doping agents neodym and praseodym normally used for the desired wavelength range are, however, not suitable as they stand to obtain the required amplification. According to the invention, neodym or praseodym is used in combination with fluorine, preferably as the compound NdF3 or PrF3.
In a preferred production process, an easily evaporable complex is formed from NdP3 and a further compound, e.g. AIF3, and taken in vapour form to a substrate for a deposition from the vapour phase.
The basic material for the amplifier light guide (10) needed therefor is to be silicon dioxide. The doping agents neodym and praseodym normally used for the desired wavelength range are, however, not suitable as they stand to obtain the required amplification. According to the invention, neodym or praseodym is used in combination with fluorine, preferably as the compound NdF3 or PrF3.
In a preferred production process, an easily evaporable complex is formed from NdP3 and a further compound, e.g. AIF3, and taken in vapour form to a substrate for a deposition from the vapour phase.
Description
The invention concerns an optical waveguide according to the characterizing clause of patent claim 1.
An optical waveguide with the features mentioned therein is known in many instances, e.g. from telcom report 6 (1983) supplement: "Communication By Means Of Light", pages 29 - 35. Optical waveguides of such a structure and composition serve as the transmission medium of optical communication technology.
It is known from the February 1991 Journal of Lightwave Technology, Vol.9, No.2, pages 220 - 227, that light in the wavelength range around 1530 nm can be amplified with such optical waveguides, if their core contains erbium as the laser-active substance. On this basis, there are fiber-optic amplifiers being used very successfully in systems operating in the wavelength range around 1530 nm.
It is an entirely different matter with the 20 wavelength range around 1300 nm: As established in the introductory part of publication PD 12/1 to PD 12/4, OFC/IOOC '93, February 21 - 26, 1993, San Jose Convention Center, San Jose California, no practical realizable fiber-optic amplifiers exist so far for this wavelength range. The wavelength range around 1300 nm is used in many optical communication systems which are installed at the present time. The advantage lies in that the transmission characteristics of the optical waveguide of the kind mentioned in the beginning are more favorable in 30 the 1300 nm range than in the 1500 nm range, e.g. the minimum dispeIsion of such optical waveguides is around 1310 nm. It would therefore be desirable to have an optical waveguide for amplifying light in the wavelength range around 1300 nm.
Among fiber-optic amplifiers for the 1300 nm range suggested in the above mentioned publication, the amplifier wit~, the praseodymium (Pr)-doped fluoride fiber was indicated as the most promising. However, as is known from: "Lasers and Optronics", August 1991, pages 43 - 46, particularly the right column on page 44, optical waveguides with fluoride glass as the basic material exhibit great disadvantages when compared to optical waveguides wit:h silicon dioxide as the basic material, 10 since the former are weak, hygroscopic and cannot be spliced by fusion to sio2 optical waveguides. The same problem exists for fiber-optic amplifiers containing a neodymium (Nd)-fluoride fiber.
It woulcl therefore be desirable to have an amplifying optical waveguide for the 1300 nm range, which has silicon dioxide as its basic material. It is known from the above mentioned "Journal of Lightwave Technology" publication, left column on page 220, that it 20 is not a practical idea to dope the basic silicon dioxids material with Nd to obtain a fiber-optic amplifier that is suitable for the 1300 nm wavelength range, because at this wavelength the effectiveness is strongly limited by absorption uncler conditions of excitation.
It is known from FP-A-0 466 932 to insert a fluoride of a rare earth element, e.g. NdF2, and a fluoride of aluminum (AlF2) into porous glass rod preforms, because the fluorides have relatively lower melting points.
It is further known to heat the porous preforms in an 30 oxygen atmosphere prior to sintering, and (see page 9, lines 9-12) to sinter the porous glass preforms in a helium atmosphere that contains oxygen, in such a way that the glass rods produced by the sintering contain neodymium and fluorine among others, where neodymium is combined with oxygen (Nd2O2) and fluorine is not chemically combined with another element (page 11, line 56).
2l575l4 It is known from DE-A-4 120 054 (column 10, lines 3 to 30) to provide a SiO2 buffer layer on a substrate material made of a multi-component glass, with the layer containing at least one doping substance that controls the index of refraction, such as B, P, Ti, Ge, Ta, Al, F. In addition, one of two core waveguide contains at least one rare earth metal, such as Yb, Er or Nd, which contributes to the optical amplification.
Optical waveguides, which are doped with rare earth ions, 10 are known from the February 1991 "Journal of Lightwave Technology", Volume 9, no. 2, pages 234 to 250. The article discusses what could be an advantageous doping material, with the result that fluorine would not have any useful effect and that aluminum is seen as the most favorable additional doping material.
The tas~ of the invention is therefore to present the composition of an amplifier-opti~al waveguide, which is suitable for the 1300 nm wavelength range.
One solution of the task with neodymium as the doplng agent is indicated in cl~ A~_ /
/
solution with praseodymium as the doping agent is indicated in claim 2. Further developments are indicated in the subclaims. An advantageous method for producing the new optical waveguide is the subject of claims 6 to 9. One aspect of the invention is that the new optical waveguide also created a new fiber-optic amplifier. This is the subject of claim 9.
The invention will now be explained in greater detail by means of the drawings, which illustrate:
Figure 1 a fiber-optic amplifier for the wavelength range around 1300 nm, with the new optical waveguide as an amplifying optical waveguide, and Figure 2 a device for performing the preferred method to produce the new optical waveguide.
The reference number 10 in figure 1 denotes a schematically indicated amplifier-optical waveguide of a fiber-optic amplifier. At splicing points 11 and 12 it is connected to an optical waveguide 13 which conducts the optical input signal to be amplified, or to an optical waveguide 14 which conducts the amplified optical output signal of the fiber-optic amplifier. As is customary with fiber-optic amplifiers, a pumping light source 15 is ~rovided, which in the depicted case is coupled to the optical waveguide 13 by a coupler 16. As is often the case in such illustrations, the amplifier-optical waveguide 10 is drawn with a thicker line to distinguish it from the normal optical waveguides 13 and 14, even though it has the same diameter. The wavelength of the light passing through such a fiber-optic amplifier is in the range of 1300 nm. A digital signal is indicated at the input as well as at the output, which in the latter case is depicted as an amplified signal.
It is essential for the invention that the optical waveguide, which is designed as an amplifying optical 21~7~14 -waveguide for the 1300 nm range, has the following composition:
Silicon dioxide is the basic material of the entire optical waveguide; as is customary, the core of the optical waveguide contains a doping agent which increases the index of refraction, e.g. GeO2, and additionally neodymium (Nd) and fluorine in accordance with the invention. The composition of the sheath is not significant. It is important that the neodymium is combined with fluorine, i.e. that the neodymium is surrounded by fluorine ions. The fluorine ions may not be displaced by oxygen ions. The neodymium and fluorine medium provides the neodymium with the desired laser property, which is required to amplify light in the wavelength range around 1300 nm. One possibility of surrounding the neodymium with fluorine is for the core to contain neodymium and fluorine in the form of a compound NdF3.
Instead of neodymium, the core may also contain praseodymium (Pr). The same applies to the surrounding by fluorine, and in the case of praseodymium it is also advantageous for the core to contain praseodymium and fluorine in the form of a compound PrF3.
Any method is suitable to manufacture the optical waveguide of the invention, if it combines neodymium and fluorine or praseodymium and fluorine in the core of an optical waveguide using silicon oxide as its basic material.
For example, it is possible to guide gaseous BF3 through heated NdF3 powder and in this way to transport the NdF3 to the place where it precipitates on a substrate, in order to dope the SiO2 material with NdF3.
2ls7sl4 -In a particularly advantageous method, NdF3 or PrF3 is brought close to a substrate as a complex with another vaporous combination, in conjunction with output materials of a chemical vapor reaction from which the core material originates, so that it can precipitate on the substrate together with the chemical vapor reaction products. The chemical vapor reaction can be performed in a substrate tube, for example in accordance with the known MCVD process, so that the substrate tube is coated on the inside. Such a process is explained in the following as an example of a method for precipitating a chemical vapor reaction.
As an alternative to such an MCVD process, wherein the substrate is a quartz tube which is coated on the inside, the method may also be one in which the substrate tube is a rod-shaped mandrel which is coated on the outside, or it may be a base that rotates around its axis, on which the glass core material and potentially also the glass sheath material is created by coating in the axial direction through a chemical vapor reaction.
The principle of these three known variations of methods to precipitate with a chemical vapor reaction is known from the above mentioned telcom report publication.
It is essential for the preferred method of producing the new optical waveguide, that NdF3 or PrF3 is guided to the substrate together with another suitable compound and the output materials of the chemical vapor reaction used to produce the glass core material, so that it can precipitate on the substrate together with the product of the chemical vapor reaction.
In the configuration example of a suitable method described below, the cited other compound is aluminum trifluoride (AlF3). Aluminum trifluoride is a compound that is suitable for forming a complex with NdF3 or PrF3, 21~7514 which has a clearly lower vaporization temperature than NdF3 or PrF3. Lanthanum trifluoride (LaF3) can also be used instead of aluminum trifluoride, or any other compound which is able to form the cited complex with a clearly lower vaporization temperature. In the case of AlF3 or LaF3, an optical waveguide is the result which, in addition to the components cited so far, contains the further comporlent aluminum or lanthanum, namely in an AlF3 or LaF3 compound. These components are a consequence of the productior~ method and do not achieve the desired optical properties.
The following is essential for the optical properties:
The core contains the neodymium or praseodymium built into a sio~ matrix, which has a fluorescence band that uniformly covers the range of 1280 to 1330 nm. Neodymium or praseodymium is always surrounded by fluorine. An amplifier-optical waveguide with such a core can be directly used in optical waveguide communication systems that utilize the 1330 nm range.
A conficJuration example of a preferred method is explained in ~he following by means of figure 2, which illustrates a device for carrying out the method.
The manufacture of an amplifying optical waveguide takes place with an optical waveguide preform in accordance with the MCDV process in such a way, that a rotating substrate tube, which is usually made of quartz glass, is clamped in a glass lathe, where it is coated with the sheath or core layers of an artificial glass during several passes. The output materials for the sheath or core layers are guided in gaseous form into the substrate tube. The continuous lengthwise heating of the substrate tube with an oxyhydrogen gas blow pipe produces a continuous layer of artificial glass of a predetermined 21~7514 composition on the inside wall of the substrate tube, through the precipitation from a chemical vapor reaction.
The length of the substrate tube is usually 1250 mm. The output materials for producing the layers of artificial glass for example are silicon tetrachloride (SiCl4), germanium tetrachloride (GeCl4), phosphorus oxytrichloride (OPCl3), and potentially hexafluorethane (C2F6) together with oxygen and helium.
Figure 2 illustrates part of a device for carrying out the method of the invention, clamped in a glass lathe. This clevice contains the tube 1 with a larger diameter at the left end. Its diameter corresponds approximately to the diameter of the substrate tube 5.
About in the center of the device - its total length is approximately 350 mm - the tube 1 narrows into a tube 2 with a smaller diameter. Tube 2 is surrounded by another larger diameter tube 3, which is closed at the left end and is connected to tube 1, and which contains an enlargement 4 with rotational symmetry.
The substrate tube 5 to be coated is fused to the right end of t:ube 3. It has a length of 900 mm for example. The left end of the device, i.e. the tube 1, is able to rotate in the glass lathe 6 and is driven by drive 7.
When the device operates, the materials needed to carry out the method of the invention are contained in the enlargemer,t 4, namely aluminum fluoride (AlF3) as the complex builder and neodymium fluoride (NdF3). The aluminum fluoride and neodymium fluoride output materials are available in powder form.
They are filled into the enlargement at the ratio of 3-4 to l (3 to 4 parts of AlF3 to 1 part of NdF3). The enlargement 4 and the materials contained therein are not 21~7~ 1~
heated during this phase of the process. The enlargement 4 and the materials contained therein are only heated to 1400C when the core layer doped with the rare earth element is to be produced.
When the mixture of aluminum trifluoride and neodymium trifluoride is heated, the two form a complex containing a considerable vapor pressure, which is sufficient to insert the vaporized complex into the substrate tube.
A melting point of over 2000C is indicated for neodymium trilluoride. Heating this compound to a temperature ol 1300C would not produce the vapor pressure needed to insert this compound into the substrate tube.
The complex created with the mixture - the stoichiometry is assumed to be 3 (AlF3) x NdF3 - enters the substrate tube together with SiCl4, GeCl4, oxygen, helium and potentially hexafluorethane, where it is incorporated into the oxide mass behind the burner in a controlled "thermophoretic" manner. It is important for the complex (it could be called fluoro-complex) to be incorporated; the fluorine ions may not be displaced by oxygen ions.
When carrying out the suggested method to manufacture the optical waveguide preform with a core layer doped with NdF3 or PrF3 or both, it proved to be useful to manufacture another core layer without such doping in a subsequent step, after the NdF3 or PrF3 doped core layer has been produced, and then, before collapsing the substrate tube, to remove about 70% of the total thickness of the first and the second core layer by etching, for example with hexafluorethane. The result is 21 ~-751~
-a particularly pure core layer, which has a definite rectangular core profile.
An optical waveguide with the features mentioned therein is known in many instances, e.g. from telcom report 6 (1983) supplement: "Communication By Means Of Light", pages 29 - 35. Optical waveguides of such a structure and composition serve as the transmission medium of optical communication technology.
It is known from the February 1991 Journal of Lightwave Technology, Vol.9, No.2, pages 220 - 227, that light in the wavelength range around 1530 nm can be amplified with such optical waveguides, if their core contains erbium as the laser-active substance. On this basis, there are fiber-optic amplifiers being used very successfully in systems operating in the wavelength range around 1530 nm.
It is an entirely different matter with the 20 wavelength range around 1300 nm: As established in the introductory part of publication PD 12/1 to PD 12/4, OFC/IOOC '93, February 21 - 26, 1993, San Jose Convention Center, San Jose California, no practical realizable fiber-optic amplifiers exist so far for this wavelength range. The wavelength range around 1300 nm is used in many optical communication systems which are installed at the present time. The advantage lies in that the transmission characteristics of the optical waveguide of the kind mentioned in the beginning are more favorable in 30 the 1300 nm range than in the 1500 nm range, e.g. the minimum dispeIsion of such optical waveguides is around 1310 nm. It would therefore be desirable to have an optical waveguide for amplifying light in the wavelength range around 1300 nm.
Among fiber-optic amplifiers for the 1300 nm range suggested in the above mentioned publication, the amplifier wit~, the praseodymium (Pr)-doped fluoride fiber was indicated as the most promising. However, as is known from: "Lasers and Optronics", August 1991, pages 43 - 46, particularly the right column on page 44, optical waveguides with fluoride glass as the basic material exhibit great disadvantages when compared to optical waveguides wit:h silicon dioxide as the basic material, 10 since the former are weak, hygroscopic and cannot be spliced by fusion to sio2 optical waveguides. The same problem exists for fiber-optic amplifiers containing a neodymium (Nd)-fluoride fiber.
It woulcl therefore be desirable to have an amplifying optical waveguide for the 1300 nm range, which has silicon dioxide as its basic material. It is known from the above mentioned "Journal of Lightwave Technology" publication, left column on page 220, that it 20 is not a practical idea to dope the basic silicon dioxids material with Nd to obtain a fiber-optic amplifier that is suitable for the 1300 nm wavelength range, because at this wavelength the effectiveness is strongly limited by absorption uncler conditions of excitation.
It is known from FP-A-0 466 932 to insert a fluoride of a rare earth element, e.g. NdF2, and a fluoride of aluminum (AlF2) into porous glass rod preforms, because the fluorides have relatively lower melting points.
It is further known to heat the porous preforms in an 30 oxygen atmosphere prior to sintering, and (see page 9, lines 9-12) to sinter the porous glass preforms in a helium atmosphere that contains oxygen, in such a way that the glass rods produced by the sintering contain neodymium and fluorine among others, where neodymium is combined with oxygen (Nd2O2) and fluorine is not chemically combined with another element (page 11, line 56).
2l575l4 It is known from DE-A-4 120 054 (column 10, lines 3 to 30) to provide a SiO2 buffer layer on a substrate material made of a multi-component glass, with the layer containing at least one doping substance that controls the index of refraction, such as B, P, Ti, Ge, Ta, Al, F. In addition, one of two core waveguide contains at least one rare earth metal, such as Yb, Er or Nd, which contributes to the optical amplification.
Optical waveguides, which are doped with rare earth ions, 10 are known from the February 1991 "Journal of Lightwave Technology", Volume 9, no. 2, pages 234 to 250. The article discusses what could be an advantageous doping material, with the result that fluorine would not have any useful effect and that aluminum is seen as the most favorable additional doping material.
The tas~ of the invention is therefore to present the composition of an amplifier-opti~al waveguide, which is suitable for the 1300 nm wavelength range.
One solution of the task with neodymium as the doplng agent is indicated in cl~ A~_ /
/
solution with praseodymium as the doping agent is indicated in claim 2. Further developments are indicated in the subclaims. An advantageous method for producing the new optical waveguide is the subject of claims 6 to 9. One aspect of the invention is that the new optical waveguide also created a new fiber-optic amplifier. This is the subject of claim 9.
The invention will now be explained in greater detail by means of the drawings, which illustrate:
Figure 1 a fiber-optic amplifier for the wavelength range around 1300 nm, with the new optical waveguide as an amplifying optical waveguide, and Figure 2 a device for performing the preferred method to produce the new optical waveguide.
The reference number 10 in figure 1 denotes a schematically indicated amplifier-optical waveguide of a fiber-optic amplifier. At splicing points 11 and 12 it is connected to an optical waveguide 13 which conducts the optical input signal to be amplified, or to an optical waveguide 14 which conducts the amplified optical output signal of the fiber-optic amplifier. As is customary with fiber-optic amplifiers, a pumping light source 15 is ~rovided, which in the depicted case is coupled to the optical waveguide 13 by a coupler 16. As is often the case in such illustrations, the amplifier-optical waveguide 10 is drawn with a thicker line to distinguish it from the normal optical waveguides 13 and 14, even though it has the same diameter. The wavelength of the light passing through such a fiber-optic amplifier is in the range of 1300 nm. A digital signal is indicated at the input as well as at the output, which in the latter case is depicted as an amplified signal.
It is essential for the invention that the optical waveguide, which is designed as an amplifying optical 21~7~14 -waveguide for the 1300 nm range, has the following composition:
Silicon dioxide is the basic material of the entire optical waveguide; as is customary, the core of the optical waveguide contains a doping agent which increases the index of refraction, e.g. GeO2, and additionally neodymium (Nd) and fluorine in accordance with the invention. The composition of the sheath is not significant. It is important that the neodymium is combined with fluorine, i.e. that the neodymium is surrounded by fluorine ions. The fluorine ions may not be displaced by oxygen ions. The neodymium and fluorine medium provides the neodymium with the desired laser property, which is required to amplify light in the wavelength range around 1300 nm. One possibility of surrounding the neodymium with fluorine is for the core to contain neodymium and fluorine in the form of a compound NdF3.
Instead of neodymium, the core may also contain praseodymium (Pr). The same applies to the surrounding by fluorine, and in the case of praseodymium it is also advantageous for the core to contain praseodymium and fluorine in the form of a compound PrF3.
Any method is suitable to manufacture the optical waveguide of the invention, if it combines neodymium and fluorine or praseodymium and fluorine in the core of an optical waveguide using silicon oxide as its basic material.
For example, it is possible to guide gaseous BF3 through heated NdF3 powder and in this way to transport the NdF3 to the place where it precipitates on a substrate, in order to dope the SiO2 material with NdF3.
2ls7sl4 -In a particularly advantageous method, NdF3 or PrF3 is brought close to a substrate as a complex with another vaporous combination, in conjunction with output materials of a chemical vapor reaction from which the core material originates, so that it can precipitate on the substrate together with the chemical vapor reaction products. The chemical vapor reaction can be performed in a substrate tube, for example in accordance with the known MCVD process, so that the substrate tube is coated on the inside. Such a process is explained in the following as an example of a method for precipitating a chemical vapor reaction.
As an alternative to such an MCVD process, wherein the substrate is a quartz tube which is coated on the inside, the method may also be one in which the substrate tube is a rod-shaped mandrel which is coated on the outside, or it may be a base that rotates around its axis, on which the glass core material and potentially also the glass sheath material is created by coating in the axial direction through a chemical vapor reaction.
The principle of these three known variations of methods to precipitate with a chemical vapor reaction is known from the above mentioned telcom report publication.
It is essential for the preferred method of producing the new optical waveguide, that NdF3 or PrF3 is guided to the substrate together with another suitable compound and the output materials of the chemical vapor reaction used to produce the glass core material, so that it can precipitate on the substrate together with the product of the chemical vapor reaction.
In the configuration example of a suitable method described below, the cited other compound is aluminum trifluoride (AlF3). Aluminum trifluoride is a compound that is suitable for forming a complex with NdF3 or PrF3, 21~7514 which has a clearly lower vaporization temperature than NdF3 or PrF3. Lanthanum trifluoride (LaF3) can also be used instead of aluminum trifluoride, or any other compound which is able to form the cited complex with a clearly lower vaporization temperature. In the case of AlF3 or LaF3, an optical waveguide is the result which, in addition to the components cited so far, contains the further comporlent aluminum or lanthanum, namely in an AlF3 or LaF3 compound. These components are a consequence of the productior~ method and do not achieve the desired optical properties.
The following is essential for the optical properties:
The core contains the neodymium or praseodymium built into a sio~ matrix, which has a fluorescence band that uniformly covers the range of 1280 to 1330 nm. Neodymium or praseodymium is always surrounded by fluorine. An amplifier-optical waveguide with such a core can be directly used in optical waveguide communication systems that utilize the 1330 nm range.
A conficJuration example of a preferred method is explained in ~he following by means of figure 2, which illustrates a device for carrying out the method.
The manufacture of an amplifying optical waveguide takes place with an optical waveguide preform in accordance with the MCDV process in such a way, that a rotating substrate tube, which is usually made of quartz glass, is clamped in a glass lathe, where it is coated with the sheath or core layers of an artificial glass during several passes. The output materials for the sheath or core layers are guided in gaseous form into the substrate tube. The continuous lengthwise heating of the substrate tube with an oxyhydrogen gas blow pipe produces a continuous layer of artificial glass of a predetermined 21~7514 composition on the inside wall of the substrate tube, through the precipitation from a chemical vapor reaction.
The length of the substrate tube is usually 1250 mm. The output materials for producing the layers of artificial glass for example are silicon tetrachloride (SiCl4), germanium tetrachloride (GeCl4), phosphorus oxytrichloride (OPCl3), and potentially hexafluorethane (C2F6) together with oxygen and helium.
Figure 2 illustrates part of a device for carrying out the method of the invention, clamped in a glass lathe. This clevice contains the tube 1 with a larger diameter at the left end. Its diameter corresponds approximately to the diameter of the substrate tube 5.
About in the center of the device - its total length is approximately 350 mm - the tube 1 narrows into a tube 2 with a smaller diameter. Tube 2 is surrounded by another larger diameter tube 3, which is closed at the left end and is connected to tube 1, and which contains an enlargement 4 with rotational symmetry.
The substrate tube 5 to be coated is fused to the right end of t:ube 3. It has a length of 900 mm for example. The left end of the device, i.e. the tube 1, is able to rotate in the glass lathe 6 and is driven by drive 7.
When the device operates, the materials needed to carry out the method of the invention are contained in the enlargemer,t 4, namely aluminum fluoride (AlF3) as the complex builder and neodymium fluoride (NdF3). The aluminum fluoride and neodymium fluoride output materials are available in powder form.
They are filled into the enlargement at the ratio of 3-4 to l (3 to 4 parts of AlF3 to 1 part of NdF3). The enlargement 4 and the materials contained therein are not 21~7~ 1~
heated during this phase of the process. The enlargement 4 and the materials contained therein are only heated to 1400C when the core layer doped with the rare earth element is to be produced.
When the mixture of aluminum trifluoride and neodymium trifluoride is heated, the two form a complex containing a considerable vapor pressure, which is sufficient to insert the vaporized complex into the substrate tube.
A melting point of over 2000C is indicated for neodymium trilluoride. Heating this compound to a temperature ol 1300C would not produce the vapor pressure needed to insert this compound into the substrate tube.
The complex created with the mixture - the stoichiometry is assumed to be 3 (AlF3) x NdF3 - enters the substrate tube together with SiCl4, GeCl4, oxygen, helium and potentially hexafluorethane, where it is incorporated into the oxide mass behind the burner in a controlled "thermophoretic" manner. It is important for the complex (it could be called fluoro-complex) to be incorporated; the fluorine ions may not be displaced by oxygen ions.
When carrying out the suggested method to manufacture the optical waveguide preform with a core layer doped with NdF3 or PrF3 or both, it proved to be useful to manufacture another core layer without such doping in a subsequent step, after the NdF3 or PrF3 doped core layer has been produced, and then, before collapsing the substrate tube, to remove about 70% of the total thickness of the first and the second core layer by etching, for example with hexafluorethane. The result is 21 ~-751~
-a particularly pure core layer, which has a definite rectangular core profile.
Claims (9)
1. An optical waveguide made of silicon dioxide as the basic material, with a core and a sheath, where the core contains one or more doping agents which increase the index of refraction, characterized in that the core additionally contains neodymium combined with fluorine.
2. An optical waveguide made of silicon dioxide as the basic material, with a core and a sheath, where the core contains one or more doping agents which increase the index of refraction, characterized in that the core additionally contains praseodymium combined with fluorine.
3. An optical waveguide as claimed in claim 1 or 2, characterized in that the core contains neodymium or praseodymium, further in combination with fluorine as the compound NdF3 or PrF3.
4. An optical waveguide as claimed in one of the preceding claims, characterized in that the core additionally contains aluminum or lanthanum, or an element which is able to form a compound forming a complex with NdF3 or PrF3, the vaporization temperature of which is lower than that of NdF3 or PrF3.
5. An optical waveguide as claimed in claim 4, characterized in that the core contains aluminum or lanthanum is a compound AlF3 or LaF3.
6. A method for manufacturing all optical waveguide in accordance with one of the preceding claims, in which the core material and possibly also the sheath material is produced by precipitation from a chemical vapor reaction on a substrate, and where the produced material is further processed into an optical waveguide, characterized in that a complex is formed with neodymium fluoride (NdF3) or praseodymium (PrF3) and another compound, and is supplied in vapor form to the substrate together with the output materials of the chemical vapor reaction, so that the product of the chemical vapor reaction and the complex are precipitated on the substrate.
7. A method as claimed in claim 6, characterized in that aluminum trifluoride (AlF3) or lanthanum trifluoride (LaF3) or another compound is used as the compound which forms a complex with NdF3 or PrF3, whose vaporization temperature is clearly lower than that of NdF3 or PrF3.
8. A method as claimed in claim 6 or 7, in which a quartz tube is used as a substrate, and the output products of a chemical vapor reaction are inserted into the substrate tube, characterized in that the output products of the chemical vapor reaction are inserted into the substrate tube together with the vaporized complex, so that the substrate tube is coated on the inside by precipitation of the products from the chemical vapor reaction and the complex, and that the internally coated substrate tube is further processed in the known manner into an optical waveguide.
9. Fiber-optic amplifier (16, 10, 15) with an optical waveguide (10) as the amplifying element, characterized in that the optical waveguide (10) contains the features of one of the preceding claims 1 to 5 (figure 1).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE4306933A DE4306933A1 (en) | 1993-03-05 | 1993-03-05 | Method of making a reinforcement optical fiber preform |
| DEP4306933.9 | 1993-03-05 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2157514A1 true CA2157514A1 (en) | 1994-09-15 |
Family
ID=6482030
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002157514A Abandoned CA2157514A1 (en) | 1993-03-05 | 1994-02-05 | Method of fabricating a preform for an amplifying optical waveguide, and an optical waveguide |
Country Status (11)
| Country | Link |
|---|---|
| EP (1) | EP0687391B1 (en) |
| JP (1) | JPH08507490A (en) |
| KR (1) | KR960701494A (en) |
| CN (1) | CN1065080C (en) |
| AU (1) | AU682490B2 (en) |
| CA (1) | CA2157514A1 (en) |
| DE (2) | DE4306933A1 (en) |
| ES (1) | ES2103576T3 (en) |
| FI (1) | FI954137A0 (en) |
| RU (1) | RU2141707C1 (en) |
| WO (1) | WO1994021010A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11502474B2 (en) | 2019-02-19 | 2022-11-15 | Thorlabs, Inc. | High efficiency 1.3μm emission in praseodymium doped conventional glass and fiber |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4420287A1 (en) * | 1994-06-10 | 1995-12-14 | Sel Alcatel Ag | Optical fiber for fiber optic amplifiers for the wavelength range around 1550 nm |
| DE19723833A1 (en) * | 1997-06-06 | 1998-12-10 | Alsthom Cge Alcatel | Amplifying fiber optic cable and method for its production |
| DE102004006017B4 (en) * | 2003-12-08 | 2006-08-03 | Heraeus Quarzglas Gmbh & Co. Kg | Production of blanks for laser-active quartz glass components involves granulation of suspension containing silica and dopants, heating product, and sintering product in reducing atmosphere |
| RU2627547C1 (en) * | 2016-08-16 | 2017-08-08 | Федеральное государственное бюджетное учреждение науки Научный центр волоконной оптики Российской академии наук (НЦВО РАН) | Fiber lightguide for amplifying optical radiation in spectral area of 1500-1800 nm, method of its manufacture and broadband fiber amplifier |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5262365A (en) * | 1990-02-05 | 1993-11-16 | The Furukawa Electric Co., Ltd. | Quartz glass doped with rare earth element and production thereof |
| JP2806602B2 (en) * | 1990-06-18 | 1998-09-30 | 東京瓦斯株式会社 | Fluidic flow meter |
| JP2755471B2 (en) * | 1990-06-29 | 1998-05-20 | 日立電線株式会社 | Rare earth element doped optical waveguide and method of manufacturing the same |
-
1993
- 1993-03-05 DE DE4306933A patent/DE4306933A1/en not_active Withdrawn
-
1994
- 1994-02-05 AU AU60390/94A patent/AU682490B2/en not_active Ceased
- 1994-02-05 EP EP94906907A patent/EP0687391B1/en not_active Expired - Lifetime
- 1994-02-05 KR KR1019950703724A patent/KR960701494A/en not_active Application Discontinuation
- 1994-02-05 WO PCT/EP1994/000329 patent/WO1994021010A1/en active IP Right Grant
- 1994-02-05 DE DE59402236T patent/DE59402236D1/en not_active Expired - Fee Related
- 1994-02-05 ES ES94906907T patent/ES2103576T3/en not_active Expired - Lifetime
- 1994-02-05 RU RU95121600A patent/RU2141707C1/en active
- 1994-02-05 JP JP6519503A patent/JPH08507490A/en active Pending
- 1994-02-05 CA CA002157514A patent/CA2157514A1/en not_active Abandoned
- 1994-02-05 CN CN941913775A patent/CN1065080C/en not_active Expired - Fee Related
-
1995
- 1995-09-04 FI FI954137A patent/FI954137A0/en unknown
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11502474B2 (en) | 2019-02-19 | 2022-11-15 | Thorlabs, Inc. | High efficiency 1.3μm emission in praseodymium doped conventional glass and fiber |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH08507490A (en) | 1996-08-13 |
| EP0687391B1 (en) | 1997-03-26 |
| AU6039094A (en) | 1994-09-26 |
| WO1994021010A1 (en) | 1994-09-15 |
| CN1119052A (en) | 1996-03-20 |
| FI954137A (en) | 1995-09-04 |
| DE4306933A1 (en) | 1994-09-08 |
| FI954137A0 (en) | 1995-09-04 |
| EP0687391A1 (en) | 1995-12-20 |
| RU2141707C1 (en) | 1999-11-20 |
| CN1065080C (en) | 2001-04-25 |
| AU682490B2 (en) | 1997-10-09 |
| KR960701494A (en) | 1996-02-24 |
| DE59402236D1 (en) | 1997-04-30 |
| ES2103576T3 (en) | 1997-09-16 |
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