FI117243B - Deposition of material for making optical fiber involves depositing at least one dopant deposition layer or part of deposition layer on the surface of material to be doped and/or on the surface of with the atom layer deposition - Google Patents

Abstract

A material is doped by depositing at least one dopant deposition layer or a part of a deposition layer on the surface of a material to be doped and/or on the surface of with the atom layer deposition method (ALD method). An independent claim is also included for an apparatus for doping material, comprising a mechanism for the ALD method to provide at least one dopant deposit layer or a part on the surface of the material being doped and/or on the surface of a part or parts by using the atom layer deposition method.

Description

χ 117243

METHOD FOR ALLOYING MATERIAL AND ALLOY MATERIAL

The invention relates to a method for doping porous glass material as defined in the preamble of claim 1, to doped porous glass material as defined in the preamble of claim 14 and to an optical wave guide according to claim 27.

10 PRIOR ART

The doped porous glass material is used, for example, in the manufacture of optical waveguides such as optical fibers and optical flat waveguides. By optical waveguide is meant the element used to transport the optical power.

The manufacture of optical fibers comprises 1) forming a porous glass blank during which the properties of the optical fiber are determined depending on various process parameters; 2) removing impurities from the porous glass blank; 3) sintering the porous glass blank into a solid glass blank and / or partially solid glass blank and finally 4) pulling the glass blank into an optic fiber. Optionally, glass can be added over the sintered glass blank to make the larger fibrous blank lii.

• *

Methods known in the art for producing porous fiber preforms include, for example, CVD- ····, * ··. (Chemical Vapor Deposition), OVD- (Outside Vapor Deposition), VAD- (Vapor Axial Deposition), MCVD- (Modi- 30fied Chemical Vapor Deposition), PCVD- (Plasma Activa- • 9 9 'lii). ted Chemical Vapor Deposition), DND (Direct Nanopar® ··· * tide Deposition) and sol-gel method. These methods are described, for example, in the "Handbook of Chemical Vapor Deposition: Principles, Technology, 35" and Applications, 2nd Ed., Hugh O. Pierson, 1999.

** · The CVD, OVD, VAD and MCVD methods are based on 2 117243 liquids with high vapor pressure at room temperature for use in the so-called. in a growth step wherein the liquid is evaporated to a carrier gas which is conveyed to a heated thermal reactor. In the reactor, the vaporized feedstock reacts with oxygen or an oxygen-containing compound to form oxides. Oxide particles grow as a result of agglomeration and co-sintering and drift into so-called. a collecting surface, which forms a porous glass layer of glass particles which can be further sintered into solid glass. The starting materials used in the above-mentioned processes are, for example, silicon tetrachloride SiCl4, the main raw material for quartz glass, the starting material for refractive GeO2, germanium tetrachloride GeCl4, and P205 for phosphorus oxychloride, which reduces the viscosity of the glass and thus facilitates sintering.

In addition, it is known to make optical fiber preforms by the sol-gel process. In the sol-gel process, the starting materials are generally alkoxides or salts of metals. The starting material is hydrolyzed in a solvent 20 whereby the starting material polymerizes to form a sol. When the sol is evaporated from the sol, it gels into a solid. Finally, upon heating the gel at high temperature, the remainder of the solvent and other organic material is removed and the gel crystallizes to its final form.

* 1 · 1,1 The problem with CVD, OVD, VAD, and MCVD methods in particular is that they cannot be used to produce optical fibers doped with rare earth metals. Rare earths do not contain 30 practical compounds with a vapor pressure sufficiently high at room temperature.

: 1! 1: For the preparation of optical fibers (RE-fibers) doped with rare-earth metals, it is known to use a so-called solution diluent, i.e., a cell-doping process with only basic substances. ': · The grown unalloyed fiber blank is dipped in a solution containing the alloying materials prior to sintering the fiber blank.

The problem of the solution mixing process is the poor homogeneity of the optical fibers produced and poor reproducibility of the parameters of the optical fibers between the fiber blanks. This is because manufacturing is dependent on a number of factors, for example, the penetration of a liquid into a porous material, the adherence of salts to the surface of a porous material, the penetration of gases into a material, the reaction of salts, doping, etc. which are difficult to control. For example, poor reproducibility affects the process rule and increases the cost of producing alloyed fibers.

Further, a method for producing doped optical fibers is known. by Direct Nanoparticle Deposition (DND). An advantage of said process over solution mixing is that the reactor 20 used in the process can be fed with liquid raw materials, whereby the glass particles are mixed in a flame reactor. In this way, a glass blank grown from doped glass particles is obtained which is more uniform than solution doping. Sat made. However, it is generally known that ♦ »» 25 nanoscale particles are difficult to collect because 5 * 5 li * particles follow the movements of gas flows. Also, the above method cannot be used to blend porous stains grown by other preforming methods.

The object of the invention is to eliminate the above mentioned: alloying of porous glass material; ···; ···. problems with known methods.

** «·. In particular, it is an object of the present invention to provide a novel, simple and inexpensive method for doping a glassy material of remarkable size. It is an object of the invention to provide a method which has a higher reproducibility than the prior art methods, and which ensures a uniform quality of the doped glass material. It is a further object of the invention to provide a new, improved and more uniform doped porous glass material which can be used to make optical waveguides such as optical fibers and optical flat waveguides.

SUMMARY OF THE INVENTION

The process according to the invention, the alloyed porous glass material and the optical waveguide are characterized by what is claimed.

The invention is based on research work that has surprisingly found that a method of doping a layer of dopant on a surface of a porous glass material and / or on a portion (s) of the porous glass material (ALD, Atomic Layer Deposition) ).

The Atomic Layer Growth Method is a CVD (Chemical Vapor Deposition) method in which the starting materials are applied to the substrate one at a time. After each start - "* e. Pulse of the substance, the substrate is flushed with an inert gas, leaving a chemically adsorbed mono · · · 25 layer on one surface. This layer reacts with the next • * · 1.1 starting material to form a defined partial · ··· * layer. The desired material ···· The thickness of the desired material ···· layer can be accurately determined by the number of cycles * ...: rackets required. In the present application, the atomic layer method refers to any conventional ALD method and / or method. any application and / or modification by one of ordinary skill in the art.

By the method of the invention, the layers of the dopant can be applied to all surfaces of the porous glass material, including inside the pores, so that the desired surface of the porous glass material is formed. layer of dopant.

The dopant may be one or more substances selected from substances comprising a rare earth metal such as erbium, ytterbium, neodymium and cerium, a boron group such as boron and aluminum, a carbon group substance such as germanium, tin and silicon, a nitrogen group phosphorus, a fluorine grouping agent such as fluorine, and / or silver and / or any other suitable material for porous glass. The substance may be in elemental or compound form. By way of example, the ALD method can be used to deposit oxide layers of the above materials or layers of other compounds on porous glass material.

In one embodiment of the invention, the porous glass material is a porous glass material used to make an optical fiber. The porous glass material may also be a porous glass material for use in the manufacture of an optical flat waveguide. The porous glass material may also be a porous glass material used to make any other similar element.

• 4 «; ·. The dopable porous glass material of the invention, for example a glass blank, can be produced by any conventional method such as CVD (Chemical Vapor Deposition), OVD (Outside Vapor Position). , VAD (Vapor Axial Deposition), MCVD (Modified Chemical Vapor Deposition), PCVD (Plasma Activated Chemical Vapor Deposition), DND (Direct Nano: Particle Deposition), sol-gel method. it mil- · »· · ** '. by any other similar method. By means of the said methods, for example, unalloyed porous glass material grown from simple basic materials ** .. * 35 can be stored and then, if necessary, mixed according to the present invention and further processed. »·» Sit ♦ • 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 43 43 11 11 43 11 11 11 11 11 11 43 11 11 11 11 11 11 11 11 11 11 11 11 11 sit 11 11 *

During the production of the porous glass material, it must be ensured that the porous glass material comprises reactive groups on the surface of the porous glass material and / or on a part (s) thereof. Reactive groups may be OH groups, OR groups (α coke di groups), SH groups, NH 1-4 groups, and / or any other conventional dopant reactive groups that may be doped with dopants. In one embodiment, the reactive groups are hydroxyl groups with which the dopants react during growth of the dopant layer.

By adjusting the amount of reactive groups on the surface of the porous glass material, the amount of dopant on the surface of the porous glass material can be controlled.

The hydroxyl groups are formed in the glass material in the presence of hydrogen to form both Si-H and Si-OH groups. Reactive groups such as hydroxy-20 alkyl groups may be added to the surface of the porous glass material by treating the glass material with a gas and / or a liquid containing hydrogen and / or a hydrogen compound. high temperature. In addition, reactive groups:. may be added by treating the glass material with radiation, * ** 25 such as electromagnetically or • * ·

Absorb with radiation, and then and / or before treating with, for example, hydrogen and / or hydrogen compound. The irradiated region may also be treated with any other similar agent to form reactive groups on the surface of the porous glass material and / or on any portion (s) thereof.

··· *. When compounding porous glass material, the ALD- *; · * method removes reactive groups, pre-* · * ··· * 35, such as hydroxyl groups, from effectively porous ·: · glass material, e.g. by reacting with said reactive groups * · 7 117243. If necessary, the doped porous glass material after doping can be purified by removing any remaining reactive groups and any other impurities therein.

In one embodiment, the porous glass material is silica glass, i.e., silica (SiO 2). The glass material may also be any other glass-forming oxide such as B 2 O 3, GeO 2 and P 4 O 10. The porous glass material may also be phosphor glass, fluoride glass, sulfide glass and / or any other conventional glass material.

In one embodiment, the porous glass material is partially or completely doped with one or more materials comprising germanium, phosphorus, fluorine, boron, tin, titanium and / or any other similar material.

The desired specific surface area of the porous glass material is achieved by adjusting the particle size in the manufacture of the porous glass material. When the 20 mass / volume flow is high, for example 1-100 g / min, the glass particles grow large, for example in the submicron or micron size range, before adhering to the collection surface: ·. Then the pores between the particles are I · «; ·. micrometers. With a mass / volume flow of less than 25 microns, particles of the size of 1 µm are formed on the collection surface to form a foam product, such as an optical waveguide, with a smaller pore size. Particle size can-

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...! can also be adjusted in any other way by adjusting the process parameters during the growth of the porous glass material 30. In one embodiment, the porous glass material preferably has a specific surface area of> 1 · ***. m2 / g, more preferably> 10 m2 / g, and most preferably> 100 ··· _ \ «/ g-

Once the porous glass material has been doped in accordance with the present invention, it can be further processed by conventional steps to the desired final. After the alloying of the porous glass material, it can be sintered into a solid, non-porous glass material, whereby the alloying agents diffuse into the glass material. The solid sintered glass material 5 can be further processed, for example, drawn into an optical fiber.

The invention is further based on an optical waveguide, such as an optical fiber or a planar optical waveguide, manufactured using 10 porous glass materials doped by the process of the present invention.

An advantage of the invention is that porous glass material made by several known alternative methods can be used in the process. This 15 porous glass material can be made in storage for use, for example, in the manufacture of optical fibers, or other end products, as needed. The process of the invention provides for the doping of a porous glass material with the desired dopant 20 with great precision, of uniform quality and with better reproducibility of production than by known methods.

A further advantage of the invention is that the porous • »·; ·. the ALD method used for compounding glass material * · 1. 25 allows the required amount of dopant to be increased to the desired amount and the thickness of dopant layer can be varied accurately, even to the accuracy of a partial atomic layer —ί, between glass materials.

A further advantage of the invention is that method 30 enables Sn alloying which has not previously been possible.

· · ·

A further advantage of the invention is that an accurate ··· \ adjustable process provides a commercially · 1 «inexpensive process which ensures the production of exactly the desired alloy porous glass material ··· without wasting material. .

···· · · · · ♦ • «9 117243

LIST OF FIGURES

The invention will now be described in more detail by way of exemplary embodiments with reference to the accompanying drawings, in which: Figure 1 shows a flow diagram of the manufacture of an optical fiber, and

Figure 2 illustrates the steps of making a porous glass material to seal the blank.

DETAILED DESCRIPTION OF THE INVENTION

Example 1: Preparation of Al203 / Er203 Alloyed Glass Blank

The functionality of the present invention, i.e. the use of the ALD-15 method in doping porous glass material, was investigated by applying an Ai203 / Er203 layer to the surfaces of a porous glass blank used for optical fiber production (Figure 2).

The porous glass blank was prepared according to the sol-gel method known in the art. The glass blank can also be prepared by any other conventional method of making porous glass blank. The porous glass blank was a SiO 2 blank (Figure 1, «« «** Step 1).

»# · \" 25 In the preparation of the porous glass blank by the sol-gel process, the glass blank itself contained more than * "··· * 200 ppm (w / w) hydroxyl groups. To obtain an effective ALD process, the amount of hydroxyl groups was further increased by treating the glass blank with hydrogen after irradiation of the glass blank (Figure 1, Step 2). After treatment, the amount of hydroxyl groups was ··· 1000 ppm.

After the preparation of the glass blank, the <tb> * · ί Al203 / Er203 layers were grown on the porous glass blank surfaces *. · 35 using the ALD method (Figure 1 # step 3).

m ... Al203 can be used as a starting material, for example. as the following starting materials: • ··· »10 1 17243 A1X3, where X is F, Cl, Br or I, X3AI, i.e. an organometallic compound where X is H, CH3, CH3CH2, (ΟΗ3) 2αΗ2 etc., A1X3 / wherein X is an oxygen or nitrogen co-ordinated ligand, for example, ethoxide, isopropoxide, 2,2,6,6, -tetramethylheptanedione, acetylacetonate or Ν, Ν-dialkylacetamidinate.

In addition to the above, compounds wherein the ligands are combinations of the above may be used.

Examples of starting materials for erbium include the following:

ErX3 where X is F, Cl, Br, I or nitrate, Er (X) 3 or Er (X) 3Z, where X is an oxygen coordinated ligand, for example one or more of the following: 2,2,6,6, -tetramethyloctane dione, 2,2,6,6, -tetramethyl heptane dione or acetylacetate or the like; and Z is, for example, tetraglyme, pyridine N-oxide, 2,2'-bipyridyl or 1,10-20 tenanthroline or a similar neutral ligand, X3Er or X3ErZ, wherein X is C5Z5 (Z = H or R) or a derivative thereof or the like ηχ, η5 or η8- choor; ·. a dinated ligand and Z is a neutral ligand, • * «• · β ErX3, where X is nitrogen coordinated •» »\. A ligand, for example, alkylsilylamido or N, N- * * *, [· '] dialkylacetamidinate.

• For both aluminum and erbium starting materials, an oxygen-containing compound such as water, hydrogen peroxide, oxygen, ozone or various metal alkoxides may be used as the second starting material.

. ···. In this experiment, (CH 3) 3 Al and Er (thd) 3 (thd = C n H 2 O 2) were used as starting materials. Water and ozone were used as the oxygen source. At 35 ° C 300 ° C was used. The growth sequence was performed by changing the pulse ratio between Er (thd) 3/03 and (CH 3) 3Al / H 2 O between 1: 0 and 0: 1.

• ·· • »11 1,17243

The ALD doping involved two steps (Figure 1, Step 3). First, an Al 2 O 3 layer (as Ax in Figure 1) using the starting materials (CH 3) 3A 1 and H 2 O (as shown in Figure 1 5) and then an Er 2 O 3 layer (as shown in Figure 1 by using starting materials) was applied to the glass blank surfaces. Er (thd) 3 and 03 (starting materials 3 and 4 shown in Figure 1). The cycle was continued until a sufficiently thick layer * 10 ALD method was found to be an effective method for the preparation of Al 2 O 3 / Er 2 O 3 porous glass preform. The amounts required in a typical Er blend and the ratios of the substances to be doped were achieved by the ALD method at low cycle numbers. Thus, process time and costs remained low.

Further, it was found that Al 2 O 3 doping can be used to increase the refractive index instead of the expensive 20 GeO 2 doping conventionally used to increase the refractive index.

After doping, the remaining OH groups were removed (Figure 1, Step 4) and then the porous glass blank was compacted (Figure 1, Step 5), during which the di fusion forces smoothed the surface of the pores. while forming the concentration ratio of the glass blank

• · »J

• * * evenly porous Al203 and Er203 doped porous blanks.

• "** ·;" Then a m * · * · * silica sheath was formed around the blank (Figure 1, Step 6). Finally, the blank and sheath were sintered (Figure 1, Step 7), resulting in a clear fiber blank which was pulled into fiber (Figure 1, Step 8).

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The invention is not limited to the above embodiment only, but many modifications are possible within the scope of the inventive idea defined by the claims.

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Claims (27)

Method for doping a porous glass material, characterized in that in the process a layer of a dopant is deposited on the surface of the porous glass material and / or on the surface of a part / parts thereof by an atomic layer deposition technique (ALD technique). - Method according to claim 1, characterized in that the dopant comprises one or more substances comprising a rare earth metal, such as erbium, outer bium, neodymium and cerium, a substance in the boron group such as boron and aluminum, a substance in the carbon group, such as germanium, tin and silicon, a substance in the nitrogen group, such as phosphorus, a substance in the fluorine group, such as fluorine, and / or silver. 15 3. A method according to claim 1 or 2, characterized in that the porous glass material is a porous glass material used in the production of an optical fiber or an optical flat guide. Process according to any of claims 1-3, characterized in that the porous glass material is a glass semi-finished product. Process according to any of claims 1-4, characterized in that the porous glass material is prepared by one of the following techniques: CVD (Chemical Vapor), OVD (Outside Vapor Deposition) ), VAD- • · * '! (Vapor Axial Deposition), MCVD (Modified Chemical Vapor · ** ···· Deposition), PCVD (Plasma Activated Chemical Vapor Deposition), DND (Direct Nanoparticle Deposition) and Solgel - the technique. 30 Method according to any one of claims 1-5, characterized in that the glass material comprises reactive groups to which the dopants adhere. 7. Method according to claim 6, characterized in that the amount of dopant on the m-m surface of the porous glass material is controlled by controlling the amount of reactive groups in the * * / *: the porous glass material. 117243 Process according to claim 6 or 7, characterized in that the reactive groups are OH groups, OR groups, SH groups and / or NH 1 - groups. Process according to any of claims 6-8, 5, characterized in that the amount of reactive groups on the surface of the porous glass material is increased by treating the glass material with a gas and / or a liquid comprising hydrogen and / or a hydrogen compound at a high temperature. . Process according to any of claims 6-8, 10, characterized in that the amount of reactive groups on the surface of the porous glass material is increased by treating the glass material by means of a combination of radiation and treatment with hydrogen. Process according to any of claims 1-10, characterized in that the porous glass material is quartz glass, phosphorus glass, fluoride glass and / or sulfide glass. Process according to any one of claims 1-11, characterized in that the porous glass material is partially or completely doped with one or more substances comprising germanium, phosphorus, fluorine, boron, tin and / or titanium. Method according to any of claims 1-12, characterized in that the specificity of the porous glass material. fair area is> 1 m2 / g, advantageously> 10 m2 / g and more preferably> 100 m2 / g. • *. ***. 25 Doped porous glass material, characterized in that a layer of a dopant is deposited on the surface of the porous glass material and / or the surface of a part (s) thereof by an atomic layer deposition technique (ALD technique). . # 15. Doped porous glass material according to claim 14, characterized in that the dopant comprises one ***** or more substances comprising a rare earth metal, such as erbium, outer bium, neodymium. and cerium, a substance in boron. The group such as boron and aluminum, a substance in the carbon group, such as germanium, tin and silicon, a substance in the nitrogen group, such as phosphorus, a substance in the fluorine group, such as fluorine, * / ·: and / or silver 15 Vapor Deposition), DND (Direct Nanoparticle Deposition) and Solgel Technology. Doped porous glass material according to claim 14 or 15, characterized in that the porous glass material is a porous glass material used in the production of an optical fiber or an optical planar conductor. Doped porous glass material according to any of claims 14-16, characterized in that the porous glass material is a glass semi-finished product. Doped porous glass material according to any of claims 14-17, characterized in that the porous glass material is produced by one of the following techniques: CVD (Chemical Vapor Deposition), OVD (Outside Vapor Deposition), VAD- ( Vapor Axial Deposition, MCVD (Modified Chemical Vapor Deposition), PCVD (Plasma Activated Chemical) Doped porous glass material according to any of claims 14-18, characterized in that the glass material comprises reactive groups to which the doping agents adhere. Doped porous glass material according to claim 19, characterized in that the amount of dopant on the surface of the porous glass material is regulated by regulating! * · *. the amount of reactive groups in the porous glass material. • V: Doped porous glass material according to claim 19 • 25 or 20, characterized in that the reactive groups are · # * OH groups, OR groups, SH groups and / or NH 1 groups. * 1111 22. Doped porous glass material according to any of claims 19-21, characterized in that the amount is reactive. groups on the surface of the porous glass material are increased by treating the glass material with a gas and / or a liquid which comprises * hydrogen, and / or a hydrogen compound at a high temperature. ·· ratur. «« «« · * · * ► 23. Doped porous glass material according to any of the claims »» »\ tent claims 19-21, characterized in that the amount of reactive • M 35 groups on the porous glass material surface is increased by V *: treating the glass material using a combination of straining and treatment with hydrogen. Doped porous glass material according to any of claims 14-23, characterized in that the porous glass material is quartz glass, phosphor glass, fluoride glass and / or sulfide glass. Doped porous glass material according to any of claims 14-24, characterized in that the porous glass material is partially or completely doped with one or more airmen comprising germanium, phosphorus, fluorine, boron, tin 10 and / or titanium. Doped porous glass material according to any of claims 14-25, characterized in that the specific surface of the porous glass material is> 1 m2 / g, advantageously> 10 m2 / g and more preferably> 100 m2 / g. 27. Optical guidance, the preparation of which used a porous glass material doped by a method according to claim 1. «# 1 • 1 2 3» i • i • 1 • ·· »· • 1« • · «• · «« · • »» 1 «•» • «···« · · 9 9 9 · «« m «» ··· t II · ··· ··· • 9 • t 2 9 9 • 3 · «·· • · • I · • M * ·