KR101424998B1 - Apparatus and method for fabricating glass bodies using an aerosol delivery system - Google Patents

Abstract

The present invention is directed to a method of making a glass body comprising a plurality of components and wherein at least one of the components is a dopant (e.g., a rare earth element) having a low vapor pressure (LVP) precursor, wherein an aerosol is generated from the LVP precursor (B) heating the aerosol and the vapor to a vapor deposition system comprising a substrate; (c) forming at least one doped layer on the surface of the substrate; (d). < / RTI > In one embodiment, the method includes filtering the aerosol to remove aerosol particles outside of a particular range of sizes. The invention also relates to an inventive aerosol generator particularly useful for generating aerosols of rare earth dopants. The present invention describes certain aspects relating to Yb-doped optical fibers.

Optical fiber, LVP precursor, deposition system, glass body, rare earth dopant

Description

TECHNICAL FIELD [0001] The present invention relates to an apparatus and a method for manufacturing a glass body using an aerosol delivery system,

The present invention and its various features and advantages can be readily understood from the following detailed description with reference to the accompanying drawings.

1 is a partial isometric view illustrating an apparatus for fabricating a rare earth (RE) -doped optical fiber in accordance with an aspect of the present invention.

Figure 2 shows two side views (part (A) and part (B)] and an end view (part (C)) of an aerosol generator according to another aspect of the present invention. Part A is a side view along arrow A of part C while part B is a side view along arrow B of part C. [ The heaters 12.4a, 12.4b of the part (A) are shown schematically.

3 is a partial isometric view of a supply tube having a concentric inner tube embedded to vaporize the aerosol prior to introduction into the MCVD parent tube, in accordance with another aspect of the present invention.

4 is a graph showing how the transmittance of Yb-doped silica fibers is deteriorated (photodarkening) over time for two different cases.

Cross-reference to related application

This application is a continuation-in-part of U.S. Provisional Patent Application Serial No. 60 / 542,502, filed December 16, 2005, entitled " Aerosol Delivery Method for Optical Fiber and Fiber Preform Fabrication, " 750,966.

Field of invention

The present invention relates to glass bodies (e.g., optical fibers, planar waveguides, glass soot) and more particularly to apparatus and methods for manufacturing rare earth (RE) doped optical fibers.

Discussion of related technologies

In standard MCVD techniques for fabricating optical fibers, the parent material is prepared by flowing relatively high vapor pressure (HVP) precursor glasses (eg, SiCl ₄ , GeCl _4, and POCl ₃ ) and oxygen under a rotating silica base tube. The external hydrogen-oxygen torch slowly traverses the tube length direction to locally heat the small section of the tube. As the gas stream moving farther than the torch approaches the touched compartment, it is heated to a temperature sufficient to cause the precursor to react with oxygen to form oxide aerosol particles. These particles are colloidal and coalesce to increase in size. As the gas stream leaves the torpedo compartment, it remains hot compared to the tube wall. Due to this temperature gradient between the tube and the gas stream, aerosol particles migrate along the tube wall and are deposited on the tube wall to form a soot layer. As the torch passes through this soot layer, the soot is sintered and converted into a solid glass layer. Although the process may be repeated to deposit a plurality of glass layers on the inner wall of the tube, for example, hundreds of layers may be deposited to produce the cores of conventional silica fibers, typically a number of smaller number of layers 3 to 15 layers) are deposited to produce RE-doped fiber cores. After the layer deposition is terminated, the tube is heated to collapse to form a solid rod known as a preform. The optical fiber is drawn out from the base material using standard techniques.

Not all suitable dopants can be delivered using the standard MCVD method because there is no suitable HVP precursor. Suitable precursors should have relatively high vapor pressures (at least about 1 torr at room temperature) and should not contain any chemicals (e.g., hydrogen, water) that will adversely affect the properties of the deposited glass. Some desirable dopants, such as RE elements (especially erbium (Er) and ytterbium (Yb)) have low vapor pressure (LVP) precursors and can not be delivered using a convenient vapor phase approach such as standard MCVD.

To solve this problem, several manufacturing methods using LVP RE precursors have been developed in the prior art, but all have significant limitations. Below we briefly describe the most common methods and the most significant limitations of these methods.

Solution Doping : The soot layer is deposited on the inner wall of the substrate tube using standard dopants, but the soot layer is not sintered. The soot layer is immersed in a liquid solution containing the LVP RE precursor. When the solution is drained from the tube, the soot layer acts like a sponge holding a predetermined amount of solution in the pores of the soot. The soot layer containing the LVP precursor is dried, the LVP precursor is oxidized, and the soot layer is sintered. Solution doping has the following limitations: (i) the reproducibility of the LVP dopant concentration is poor depending on the parent material; (ii) the amount of liquid retained by the soot layer depends on the porosity, which is very difficult to control; (iii) the process is very time consuming, taking about 1-2 hours per deposited glass layer compared to about 10 minutes for a standard MCVD glass layer.

Chelation method : The base material is prepared using the chelate precursor of the RE element. Chelates are large organo-metallic compounds with relatively high vapor pressures. The chelating process has the following limitations: The chelate contains undesirable elements such as hydrogen and has not produced glass with the purity required to date for high quality optical fibers.

Steam transfer : An ampoule containing the desired LVP RE precursor is placed inside the MCVD substrate tube. The ampoule is heated to a temperature high enough to obtain the required vapor pressure using an external heating source (e.g., flame or furnace). See U.S. Patent No. 4,666,247, issued May 19, 1987 to MacChesney, JB et al., Which is incorporated herein by reference. The ample approach has the following limitations: (i) The precursor vapor pressure (and its transfer rate) is very sensitive to temperature, which is very difficult to control because the external source heats the RE source material placed in several concentric glass tubes ; (ii) flowing the gas stream causes the tube to cool, which makes the actual source temperature uncertain; (iii) there is only a small surface area between the precursor and the carrier gas, so that the precursor will not saturate in the carrier gas. This changes the amount of the delivered precursor when the surface size changes or when the surface is covered, for example, by a RE oxide layer; (iv) When the precursor leaves the ampoule, some or all of the precursor reacts with ambient oxygen to form metal oxide aerosol particles. The size of these aerosol particles is not controlled. Where large particles are formed, current techniques suggest that they may form clusters and be detrimental to RE-doped parent materials and fibers.

Liquid aerosol delivery : A solution containing an organo-metal precursor for all the dopants desired for the organic solvent is sprayed into the liquid aerosol (droplet) and transferred into the substrate tube. As the liquid aerosol approaches the heating zone, the solvent evaporates and the resulting solid aerosol particles are oxidized and deposited as a soot layer onto the substrate tube. Take care not to sinter the soot layer. Two references cited herein by reference (TFMorse, et al., J. Non-Crystal. Solids, Vol. 129, pp. 93-100 (1991); And J. Aerosol Sci., Vol. 22, No. 5, pp. 657-666 (1991). Morse et al., J. Non-crystal. According to Solids, supra at page 96, column 2, "the solution must contain all of the components of the glass structure within each aerosol particle to minimize microcrystalline inclusions in the glass to ensure micro-uniformity" (underlined ""And" all "are not in the literature, but are added for emphasis). The phrase "all components" includes certain LVP RE elements such as Nd and / or Er as well as precursors of standard HVP dopants such as Ge and / or P. This liquid aerosol approach has the following limitations: (i) the solution is flammable and can explode; (ii) a new solution should be prepared whenever a different glass composition is desired; (iii) the process is time consuming; And (iv) the process is not expected to be very low, as long as the reaction product contains contaminants such as H ₂ O and H ₂ as well as the preferred free oxides.

It would therefore be desirable to provide an aerosol delivery system capable of handling LVP precursors such as RE precursors that do not have one or more of the deficiencies of the liquid aerosol delivery system described above.

It is also desirable to provide a delivery system that can be applied to MCVD systems as well as other optical fiber manufacturing systems (e.g., OVD and VAD).

Finally, it is desirable to provide a delivery system that can be applied to the manufacture of glass bodies, which typically include glass fibers as well as glass fibers and planar waveguides.

[BRIEF SUMMARY OF THE INVENTION]

According to one aspect of the present invention, Applicants have discovered that a glass body (e.g., an optical waveguide) having a plurality of components and at least one component being a first dopant (e.g., an RE element) having a first LVP precursor , Planar waveguide or glass soot). The production method of the glass body,

(A) generating a first single component aerosol (SCA) from the LVP precursor (i. E., Each first aerosol particle comprises only the LVP precursor of the first dopant)

(B) the production step (a) and the production step (b) are carried out at a location remote from the deposition system used to form the glass body;

(C) convection of the aerosol of step (a) and the vapor of step (b) from a location remote from the deposition system to a deposition system via a conduit system and

(D) forming at least one doped layer on the surface of the substrate.

In one embodiment, the glass body comprises a second dopant having a second LVP precursor, and the method further comprises forming a second single component aerosol (SCA) from the second LVP precursor (i. E., Each second aerosol particle comprises a second dopant Of the LVP precursor). The two aerosols can be kept separate from one another while being convected to the deposition system. Alternatively, they may be mixed with each other and / or with other component vapors, and then the mixture may be convected to the deposition system.

According to another aspect of the present invention,

1. A method of making a glass body comprising a plurality of components and wherein at least one component is a first dopant having a first LVP precursor,

Providing a vapor of an LVP precursor (a1) and supersaturated LVP vapor to form an aerosol (a2) to produce a first aerosol comprising first particles comprising a first LVP precursor a),

(B), separately producing steam of the other components,

(C) convection of the aerosol of step (a) and the vapor of step (b) to a vapor deposition system comprising a substrate, and

And (d) forming on the surface of the substrate at least one doped layer comprising a vaporized aerosol and a dopant contained in the vapor in step (c).

According to another aspect of the present invention, an aerosol generator includes a vessel having a first chamber and a second chamber coupled to each other in fluid flow communication. In one embodiment, the first chamber is a bubbler chamber and the second chamber is a condenser chamber. A heater surrounds the first chamber and keeps its temperature essentially constant. A primary carrier gas is supplied to the bubbler chamber through a first inlet and a lower secondary carrier gas is supplied to the condenser chamber through a second inlet. The outlet is coupled to the condenser chamber. In operation, the precursor (usually solid at room temperature) is placed in a bubbler chamber, which is heated to a relatively high temperature sufficient to liquefy the precursor and obtain the desired vapor pressure of the precursor. The primary carrier gas conveys the precursor vapor from the precursor liquid into the condenser chamber (preferably, the precursor vapor completely saturates the primary carrier gas). Since the precursor vapor can not be delivered at such a high temperature (i. E., The precursor vapor will condense on the wall of a standard tube used to deliver the vapor to the deposition system), it is introduced into the second inlet Cool quickly by gas. As a result, the aerosol of the precursor is formed in the chamber at the time of condensation and is extracted through the outlet. The aerosol can be passed through a standard tube without significant aggregation or deposition at room temperature or slightly higher temperatures, whereby the aerosol can be convected into a standard vapor deposition system with standard vapor species.

In another embodiment, the first chamber is a reaction chamber. In this case, a sub-precursor is disposed in the first chamber, and the primary gas is a gas that reacts with the negatively charged spheres to produce a precursor compound in the form of a vapor. The vapor is convected into the condenser chamber and the cooler secondary carrier gas flows into the condenser chamber and the aerosol is formed in the manner described above.

The delivery system of the present invention can be used in conjunction with various glass deposition systems such as MCVD, OVD and VAD.

DETAILED DESCRIPTION OF THE INVENTION [

Delivery system

The present invention can be applied to a method of manufacturing a glass body on a substrate. The glass body may take the form of a glass soot layer which is deposited on the surface of the heated substrate and then sintered to form a glass layer. Such a glass layer can be used, for example, to form optical fibers. Alternatively, the glass body formed by the present invention may take the form of a glass soot which is not intentionally deposited and sintered on a heated substrate but instead flows into a suitable collector (for example, the glass soot acts as an unheated substrate Collected on the surface of the vacuum bag). Such a suit can be easily removed from the collector and then used, for example, in a sol-gel process for making optical fibers. In any case, the glass body comprises at least one dopant having an LVP precursor. Such dopants include aluminum (Al) and alkaline earth metals (e.g., Be, Mg and Ca) as well as RE-elements such as Er, Yb, Nd, Tm, Ho and La or mixtures thereof.

Illustratively, the present invention can be applied to the fabrication of optical fibers by MCVD, which involves depositing a soot glass layer on the interior surface of a heated substrate tube, sintering the layer, disrupting the tube into a parent material, Followed by withdrawing the fibers. The present invention can also be applied to the fabrication of optical fibers made of VAD and OVD, which requires deposition of a soot glass layer on the outer or distal surface of a rotating cylinder, sintering the soot layer, and withdrawing the optical fiber from the parent material do. On the other hand, the present invention can also be applied to the fabrication of planar optical waveguides, which involves depositing a glass layer on the major surface of the planar substrate. For purposes of simplification and illustration only, the following description focuses on the fabrication of optical fibers using heated substrate tubes.

Various aspects of the present invention include the generation of one or more aerosols of an LVP precursor and their delivery to a deposition system. The term "aerosol" Means a particle-gas combination in which solid or liquid LVP precursor particles are suspended in a carrier gas. Each particle contains a large number (usually thousands) of LVP precursor molecules. Generally, the aerosol may be a single component aerosol (SCA) or a multicomponent aerosol (MCA). In SCA, each particle contains a molecule consisting solely of a single LVP precursor. Even when two or more aerosols are mixed, the particles retain their distinct independence. That is, each particle contains a molecule consisting of only a single precursor. In contrast, in MCA each particle comprises two or more compounds containing a dopant or a precursor of the host material and / or an oxide of the dopant or host material.

Single component aerosol

According to one aspect of the present invention, as shown in FIG. 1, an apparatus 10 for fabricating an optical fiber includes various components of an optical fiber (e.g., a host material such as silica, the LVP dopant described above, and Ge and P Lt; RTI ID = 0.0 > HVP < / RTI > dopant). The source 12 contains one or more aerosol generators 12a that provide the SCA of the LVP precursor (e.g., RE chloride). (A separate aerosol generator indicated by an apostrophe 12a 'can be used to generate the SCA of another LVP precursor.) In addition, the source 12 can also include one or more conventional vapors (Or bubblers) 12b, 12c, 12d, generally HVP precursors (e.g., chlorides of Si, Ge and PO).

The source 12 is located remote from the glass-bed deposition system 16. Illustratively, the precursor source 12 is connected to the fluid-flow transfer path in parallel to one another, or to the deposition system 16 in series fluid-flow transfer. Those skilled in the art will recognize that the system 16 may be compatible with the precursor delivery system of the present invention, for example a MCVD system, an OVD system, a VAD system, or any other deposition system. For illustrative purposes only, the following discussion assumes that the deposition system 16 is a standard MCVD system.

Thus, the MCVD system 16 generally contains a supply tube 16.1, a substrate tube 16.2, and an exhaust tube 16.3 arranged in series with one another. The heating source (i.e., torch) 16.5 is moved in the direction of arrow 16.6 along the longitudinal axis to cause the substrate tube, substrate tube, and discharge tube to rotate in the direction of arrow 16.4 about their common longitudinal axis, And heated. The vapor and aerosol precursors enter the feed tube 16.1 through a standard rotating assembly (not shown). The assembly allows the supply tube to rotate on the MCVD lathe while the delivery tube 18 is stationary. The aerosol precursor may be delivered to the system 16 as a vapor precursor using the same port or may be delivered through a separate port. The present inventors have found that it is convenient to deliver the aerosol precursor using its own port. The inventors have also found that it is desirable to deliver the vapor precursor through the supply tube and the port on the axis so that a minimum amount of tube bending is required. The design also allows the concentric tube to be easily positioned within the supply tube 16.1, as shown in tube 16.7 in the embodiment of FIG.

"Transfer" means generating a precursor and transferring the associated gas from the generator 12 to the deposition system 16 via a conduit system (e.g., tube 18).

After delivery to the MCVD feed tube 16.1, the aerosol and vapor precursor are oxidized in the high temperature region of the substrate tube 16.2, the oxide forms a deposited soot inside the substrate tube 16.2, and the deposited soot is sintered The substrate tube collapses into the base material, and the base material is drawn out to the optical fiber.

A plurality of sources 12 contain one source 12 for each of the components of the optical fiber to be formed. For example, to produce a silica optical fiber doped with RE, Ge, and P, the aerosol generator 12a provides the SCA of an RE precursor (e.g., RE-chloride such as ErCl ₃ or YbCl ₃ ) 12b) is a silica precursor (for example, providing a vapor of SiCl _4), and a steam generator (12c) is a Ge precursor (such as GeCl ₄₎ provide the steam and the steam generator (12d) of the P precursor (e.g., POCl ₃ ) ≪ / RTI >

In general, the carrier gas used for the precursor source 12 must be inert (e.g., He, Ar), advantageous in the production of high quality glass (e.g., O ₂ ), or other processing reasons Useful (e.g., N ₂ , Cl ₂ ). In the aerosol generator 12a, He is generally used because it helps to minimize foaming during sintering. On the other hand, O ₂ is commonly used in generators (bubble generators) 12b, 12c, 12d. (The metal chloride precursor is not oxidized in the bubbler since the bubbler is kept at a relatively low temperature (e.g., below 100 ° C)).

Although not shown, the addition of a carrier gas (e.g., He, O ₂ ) that can be coupled directly to the delivery system, i.e., not connected through the aerosol generator 12a or bubble generator 12b, 12c, Further sources of source (i) and / or dopant gas (e.g. SiF ₄ ), which is a vapor at room temperature, are well known to those skilled in the art, and thus it is not necessary for the bubbler to produce an essential vapor pressure.

Importantly, the aerosol generators 12a, 12a 'are so dense that the LVP dopant (e.g. RE dopant) is transferred from the low temperature to the MCVD system and maintains the standard deposition rate.

Each source 12 heats the precursor to a temperature much higher than room temperature to produce the precursor gas at the desired vapor pressure. For example, in silica and conventional dopants (such as exponentially-growing dopants such as Ge and P), the precursors are generally heated to 30 to 50 占 폚 (e.g., 38 占 폚). Furthermore, the dopants derived from the LVP precursors (e.g., RE dopants such as Er and Yb) are much more likely to be heated to 800 to 1100 ° C (eg, 900 ° C for precursor ErCl ₃ ; 950 ° C for YbCl ₃ ) There are also severe cases. However, the tube 18 connecting the generator to the MCVD system 16 is typically at a much lower temperature than the LVP dopant source in the generator 12a (e.g., 50-100 DEG C; (By a well known but not shown) heater, and the hot LVP precursor gas is concentrated and deposited on the inner wall of the tube so that the hot gases are delivered to the MCVD system through a significantly lower temperature tube I can not. The solution to this problem is to generate the LVP fiber component as an aerosol that can be delivered to the MCVD system 16 through the tube 18 maintained at room temperature or slightly above room temperature. In all cases, if the aerosol is mixed with the HVP vapor as shown in FIG. 1, the tube 18 is heated to a temperature higher than the temperature of the hottest bubblers 12b, 12c, 12d Lt; 0 > C). On the other hand, if the aerosol is delivered directly to the deposition system 16 without first being mixed with the HVP vapor, then all tubes connected to the output of the aerosol generator (e.g. 12a) may be at room temperature.

Although the present invention is not limited to the following process theory, the present inventors believe that the following phenomenon will occur. When the RE chloride aerosol enters the high temperature region of the MCVD system where oxygen is also fed, most of the aerosol is vaporized with RE chloride vapor. Then, vaporized RE chloride (gas) molecules to oxidize the RE oxide molecule formed, the art oxide molecules other oxide molecules (such as: SiO ₂ molecules) is in conflict with and deposited as soot on the inner wall of the substrate tube. After sintering, the process forms a very homogeneous glass. Significantly, the present invention allows independent control of two critical processes (dopant transport and oxidation). In the aerosol generator, a process is set up to produce particles that have a predetermined (e.g., optimal or near optimal) size range and the desired LVP dopant concentration is delivered to the headstock tube with low loss. It is believed that as aerosol particles reach the hot zone, most of them lose information about their previous size as particles as they are vaporized into their respective molecules. In the high temperature region, these vaporized molecules are oxidized. The conditions in the high temperature region can be set (e.g., optimized or nearly optimized independent of all the aerosol generator conditions) so that all of the dopants react together to form essentially homogeneous glass.

It should be noted that clusters of LVP dopants may be desirable in the rare case of glass. In this situation, the aerosol particles must be oxidized before reaching the hot zone. The LVP oxide particles should then be filtered before delivery so that the optimal cluster size is formed in the glass. Since the particles do not vaporize (change in size) in the high temperature region, the cluster size is measured by the transferred dopant oxide in this case.

Aerosol particle size

The size of the aerosol particles is preferably in the range of approximately 0.01 탆 to 1.0 탆. On the other hand, particles of 10 [mu] m can be delivered if necessary, but care must be taken to minimize the distance between the aerosol generator and the substrate tube. When the particle is significantly larger than 1 [mu] m, the particle can settle in the inner wall of the transfer tube due to its weight. When the particles are significantly smaller than 0.01 占 퐉, the particles can be deposited on the wall of the tube due to Brownian motion. In one aspect of the invention, large particles are removed during transfer, and in most cases large particles create clusters in the RE-doped fibers, and clusters are formed in undesirable processes, such as frequency up- -conversion), which is quite advantageous.

Although some RE-aerosol particles are originally removed from other components of the tube 18 or delivery system (e.g., condensation chamber 12.1 (described below)), this type of particle filtration process is not readily controlled. Thus, in accordance with one aspect of the present invention, the particles pass through a filter 14, and the filter 14 is positioned between the aerosol generators 12a, 12a 'and the deposition system 16. The filter may contain a well known diffusion battery to remove small particles (e.g., particles below 0.01 탆). In addition, to remove large particles (e.g., particles greater than 1.0 microns), the filter 14 may be a well-known cyclone, or some bend (e. G., A coil), depending on how effectively the user wishes to remove the large particles. A series of tubes, or a settling chamber.

The collection efficiency of the tube coil for a given particle size is a function of the inner diameter of the tube, the number of loops in the coil, the flow rate, and the gas and particle properties. For example, looking at YbCl ₃ particles in He flowing through four tubes with internal diameters of 1.5, 2, 3, and 4 mm, each tube has two half loops. The collection efficiencies of the different diameter coils for the 1.0 urn particles are about 92%, 65%, 27% and 12%, respectively, and the corresponding efficiencies for the 1.4 urn particles are about 99%, 84%, 48% 26%, and the corresponding efficiencies for the particles of 2.0 [mu] m are about 100%, 100%, 72%, and 42%, respectively. Thus, while small diameter (1.5 mm and 2 mm) tubes collect almost all of the particles with a size of at least about 2 microns, the diameter of the tube reaches a diameter of about 4 microns (3 mm tube) These large (3 mm and 4 mm) tubes do not collect nearly all the particles. Reference is made to DYH Pui et al., Aerosol Sci. and Tech., Vol. 7, pp. 301-315 (1987).

The aerosol particle size is typically controlled by the particle collision and fusion time, which is described in more detail below with respect to the description of the aerosol generator 12a of FIG.

Since the aerosol particle size is important for effective delivery of the LVP dopant, it is desirable to monitor the size and / or number of particles delivered to the deposition system and, in response thereto, the operation of the generator 12a, 12a 'and / It may be advantageous to include the feedback subsystem 30 in the delivery system to control the parameters. As shown in Figure 1, the feedback subsystem 30 contains a sensor 30.1 that detects the size and / or number of particles produced by the aerosol generator 12a. The monitor 30.2 processes the signals generated by the sensor 30.1 and sends a control (e.g., error) signal to the controller 30.3 to alternately transmit one or more control signals on the output bus 30.4. Subsequent control signals control the components of the delivery system that change the size and number of aerosol particles. Said components contain a mass flow controller for controlling the flow rate of the various gases and / or a heater for controlling the temperature (s) of the aerosol generator 12a.

The monitor 30.2 may contain, for example, a commercially available particle size spectrometer (not shown).

Aerosol generator

Although several methods for producing aerosols suitable for use in the present invention are taught in the prior art, a preferred scheme of the aerosol generators 12a, 12a 'is shown in FIG. According to this aspect of the invention, the aerosol generators 12a, 12a 'include a vessel 12.1, a first chamber 12.2 and a second chamber 12.3 connected in fluid-flow communication with each other. In one embodiment, the first chamber is a bubble generator chamber 12.2 located in a first (e.g., lower) portion and the second chamber is a cooler chamber 12.3 located in a second (e.g., upper) portion. The spherical section 12.8 is connected to the bottom of the bubble generator chamber 12.2. The first heater 12.4a surrounds the lower portion, i.e. both the bubble generator chamber 12.2 and the bulbous zone 12.8. The first inlet 12.5 allows a first carrier gas (e.g. He) to be fed through the tube 22 to the bulbous zone 12.8 and the second inlet 12.6 allows a cooler second carrier gas Room temperature He) through tube 24 to cooler chamber 12.3. Preferably, the second heater surrounds all (or a substantial portion) of the cooler chamber 12.3. The second heater 12.4b maintains the cooler chamber 12.3 at a temperature lower than the bubble generator chamber 12.2 to minimize condensation in the glass wall and produce the desired aerosol particle size (s). The discharge tube 26 is connected to the cooler chamber 12.3 through an outlet 12.7.

Although the above description has been proposed that the bubble generator chamber 12.2 and the cooler chamber 12.3 are respectively located at the bottom and the top of the generator 12a, one skilled in the art will appreciate that the two chambers may have different portions To side-to-side).

In the process, the spheroidal zone 12.8 is filled with a high purity LVP precursor solids (12.9) (e.g., 6 to 9 commercially available pure RE-chlorides), the solids are liquefied with the precursor and the desired vapor pressure is obtained To a relatively high temperature (e.g., 800-1,100 [deg.] C) sufficient for the following. The primary carrier gas bubbles through the liquefied precursor as it exits the precursor vapor from the precursor liquid (hot zone) to the cooler chamber 12.3 (colder zone). (Preferably, the precursor vapor sufficiently saturates the primary carrier gas in the spheroidal zone 12.8.) However, in the cooler chamber 12.3, which is maintained at a significantly low temperature (e.g., 500 ° C), the precursor vapor is supersaturated . As a result, the RE aerosol 12.0 is formed in the cooler chamber 12.3 and exits the vessel through outlet 12.7. The outlet is connected to the MCVD system 16 via a discharge tube 26 and a transfer tube 18 (Fig. 1) maintained at room temperature or slightly above room temperature by a fluid-flow transfer. More specifically, the tube 18 to prevent the HVP precursor is fused in the tube while passing the maximum temperature of the HVP bubble generator: slightly more (e.g., 38 ℃ for SiCl ₄ bubble generator (12b) in the embodiment of Fig. 1) It should be heated to a high temperature (eg 70 ° C). As described above, depending on the delivery system design, the aerosol may be delivered at room temperature or at a temperature slightly above room temperature. Once the aerosol reaches the hot zone of the MCVD system where deposition occurs in the substrate tube 16.2, the aerosol is vaporized and converted to oxide as described above.

In another embodiment of the generator 12a, the first chamber 12.2 is a reaction chamber. In this case, a sub-precursor (eg Al metal) is placed in the first chamber and heated, and the primary gas reacts with the negatively charged spheroids to form precursor compounds (eg, Al ₂ Cl ₆ ) (For example, Cl ₂ ). The vapor is convectively circulated to the chiller chamber, a lower temperature secondary carrier gas (e.g., He) flows through the chiller chamber, and the aerosol is formed in the manner described above.

In an optional embodiment, the vapor that has been convectively circulated to the second (cooler) chamber 12.3 contains at least one chemical element derived from the LVP material (precursor or negatively charged), which in the ultimately formed glass body has a dopant do. The connection between the precursor source 12 and the MCVD system 16 is illustratively controlled by a three-way valve 13a-d. Each valve has an off-vent and a run position. As shown, the valve is in the vent position to cause the generator to continue to move and transfer the precursor to the MCVD system 16 only when necessary. This feature reduces variability at start-up. When the device 10 is ready to deliver the precursor aerosol to the MCVD system 16, it rotates the pre-selected valve into its running position, which positions the corresponding selected source 12 in fluid- .

As described above, the aerosol particle size is typically measured by particle impact and fusion time. The impact time, which varies with the volume of charge (aerosol volume per carrier gas), depends on the temperature of the heater 12.4a (i.e. the temperature of the RE chloride 12.9), the flow rate of the primary carrier gas into the tube 22, To the tube 24 of the tube. On the other hand, the fusing time depends on the temperature of the heater 12.4b (i.e. the temperature of the cooler chamber 12.3), the ratio of the cooler chamber not surrounded by the heater 12.4b, the form of the cooler chamber outlet 12.7, The flow rate to the tube 24, and the temperature of the diluent gas.

The system of the present invention has a number of important features and advantages. (1) The ability to use high purity precursors, such as metal chlorides, eliminates the need for additional purification steps. (2) The size and design of the aerosol generator of the present invention allows the aerosol generator to produce essentially the same weight output over a relatively long period of time (e.g., long residence time) when bubbles are generated upon contact of the carrier gas with the precursor, (Large surface-to-volume ratio) causes the precursor vapor to reach equilibrium with the carrier gas. The generator can be easily designed to require recharging only after thousands of hours of use, which speeds up the setup time between MCVD substrates, such as a base material made only with HVP dopants. (3) The aerosol generator of the present invention is independent of other components of the system. This feature allows any number of aerosol generators (many potential dopants) to be added to the deposition system. (As mentioned above, the aerosol generators are illustratively added in parallel or successively.) The entire fiber manufacturing system incorporating the delivery system of the present invention, and thus the delivery system, It is less dependent on its performance. That is, the aerosol precursor of the present invention reaches saturation with the carrier gas, and the temperature is easier to control and more clearly known than prior art approaches. Moreover, the three-way switch allows the LVP precursor generator (and standard bubble generator) of the present invention to always reach equilibrium. (Precursor vapor pressure does not change significantly over time.)

Operating Conditions

This paragraph describes exemplary operating conditions for the MCVD fabrication of Yb-doped optical fibers according to one embodiment of the present invention. The aerosol generator (12a) contains a precursor YbCl _3. The amount of YbCl ₃ and the form of the generator allows YbCl ₃ to reach its equilibrium vapor pressure when the primary He flow through the tube 22 is flowing (bubbling) through the tube 22. The standard operating temperature of the generator is 950 ° C., but if desired, a higher or lower aerosol volume charge can be raised or lowered as desired (eg 800 ° C. to 1,100 ° C.). As described above, there are cases where generally two He flows through the tubes 22 and 24 to the aerosol generator 12a. The primary He flow through the tube 22 flows to the bottom of the bulbous section 12.8 where it is bubbled through the liquefied YbCl ₃ (12.9). An optional but preferred secondary He flow through the tube 24 occurs at room temperature to 950 캜 (e.g., 500 캜), cooling the saturated YbCl ₃ vapor, cooling the YbCl ₃ vapor to a cooler chamber 12.3 ). In addition, the secondary He flow dilutes the aerosol bulk filler. In general, the total flow rate (bubble generator volume and dilution volume) is constant and ranges from about 0.5 to 2 L / min. The standard flow rate is about 0.5 l / min for each He flow rate. A typical range is about 0.2 to 1 L / min, but higher or lower flow rates can be used.

The temperature of the heaters (12.4a, 12.4b) and the flow rate of the He carrier gas are set before the start of the run so that the system is run in equilibrium conditions. During start-up or whenever the YbCl ₃ aerosol is not delivered to the MCVD system 16, the aerosol is sent to the vent instead of the system 16 using the three-way valve 13a.

The MCVD system 16 is set and operated in a standard manner. Assuming that a non-Yb doped glass layer is desired, for example, in a fiber cladding, the layers are fabricated as a closing valve 13a, otherwise using standard MCVD techniques. Illustratively, Yb doping is only present in the fiber core, and the Yb distribution is essentially radially uniform. At the end of the last cladding layer, the valve 13a is switched so that the YbCl ₃ aerosol flows into the delivery tube. The aerosol flows with the other selected vapor dopant into the rotating seal. By turn on the valves (13b, 13c) switch off the valve (13d) switch, for example, selects the SiCl ₄ and GeCl _4. A soot is formed, deposited, and sintered inside the walls of the substrate tube 16.2 using standard MCVD methods and temperatures. No further purification steps are necessary. When the desired number of Yb-doped core layers are deposited, the flow of all aerosol and vapor dopants is stopped using three-way valves 13a-13d, respectively. The pressure in the substrate tube 16.2 decreases and the tube 16.2 collapses into the base material using standard MCVD techniques. Subsequently, the base material is again withdrawn using a standard fiber drawing technique to an optical fiber of suitable length.

Exemplary conditions for the deposition of the core layer and flow rates are as follows. (1) YbCl ₃ aerosol generator 12a: temperature of heater 12.4a = 950 ° C; The temperature of the heater 12.4b = 500 占 폚 (generally from room temperature to the temperature of the heater 12.4a); Flow velocity of the primary He (bubble generator flow velocity) = 0.5 l / min; And (2) the SiCl ₄ generator 12b: the temperature of the heater = 38 占 폚 (suitable range: 25 to 60 占 폚); the flow rate of the secondary He (dilution flow rate) = 0.5 l / min; Or flow rate = 100 sccm (suitable range: 50 to 2,000 sccm) through the steam generator 12b; And addition of O through the generator (12b) ₂ flow rate = 900sccm (preferred range: 0 to 2,000sccm); The transverse speed of the torch 16.5 = 80 mm / min (suitable range: 40 to 200 mm / min); And the deposition / sintering temperature of the base material tube 16.2 = 2,000 占 폚 (suitable range: 1,700 to 2500 占 폚).

In general, more than five cores pass (the heating source 16.6 along the substrate tube 16.2 is switched) so that a corresponding five or more RE-doped core layers are deposited. Of course, not less than five or not more than five layers may be deposited.

Suitable tubes for delivering aerosols and vapors from the generator 12 to the spinning chamber contain a Teflon tube 18 having an outer diameter of 3/8 inch. A suitable settling chamber (as optional filter 14) for filtering large YbCl ₃ particles comprises a tube with an inner diameter of 3 inches, which is capable of reducing the flow rate sufficiently to allow large particles to settle out of the carrier gas stream due to gravity .

In a still further embodiment, the process of the present invention can be carried out without the use of any organic compound (e.g. solvent or precursor) and with the use of undesirable contaminants which are by-products of the prior art use of the compound : H ₂ O and other hydrogen-containing species). In particular, the LVP aerosol particles and the carrier gas do not contain organic compounds. As a result, the process of the present invention does not require any additional purification steps to remove such contaminants.

Example

These examples describe the preparation of Yb-doped silica optical fibers. The various materials, areas and operating conditions are provided by way of example only and are not to be construed as limiting the scope of the invention unless otherwise indicated. In these examples, YbCl ₃ is the LVP precursor of Yb and Yb is used as the dopant in the silica fiber. (Yb is actually incorporated into the fiber as an oxide, but it is the Yb element that alters the particle characteristics of the doped silica, as is well known in the art.) The settling chamber is used as the filter 14.

Example  One:

Example 1 describes a Yb-Al-doped silica matrix material prepared according to the present invention. The YbCl ₃ aerosol generator 12a is maintained at 975 ° C to achieve a high concentration of Yb. The primary He flow bubbled through the molten YbCl ₃ is set to 0.5 l / min and the secondary He flow to cool the saturated YbCl ₃ vapor in the cooler chamber 12.1 is set to 0.3 l / min. The above conditions for the aerosol generator are maintained for 1 hour before delivery to allow the system to reach equilibrium.

The MCVD system 16 is set up in a general manner and all steps prior to deposition of the Yb-Al-doped silica soot layer are performed using a standard MCVD technique with an aerosol three-way valve 13a set as a vent. For deposition of the Yb-Al-doped layer, the valve 13a is switched so that the aerosol enters the transfer tube and is mixed with other precursors and process gases (e.g., He, O ₂ ). SiCl ₄ maintains the bubble generator (12b) in 38 ℃. O ₂ 100 sccm is bubbled through the SiCl ₄ precursor. Al ₂ Cl ₆ vapor is used as a precursor for Al (incorporated as oxide of silica) and flows directly into the substrate tube 16.2 at a rate of 6.7 sccm. In addition to the precursor, 900 sccm of O ₂ and 400 sccm of He flow to assist oxidation and sintering, respectively. The precursor is oxidized by heating the outer surface of the tube to 2,100 ° C by traversing the H ₂ / O ₂ torch (16.5) through the substrate tube (16.2).

A suitable number of cladding layers are deposited first. Subsequently, after the eight Yb-Al-doped core layers are deposited, the valve 13a is returned to the vent position, the pressure in the substrate tube is reduced, and the substrate tube containing the deposited layer is sealed . The relative index difference between the Yb-Al-doped region and the undoped region of the base material is 0.007 and the Yb concentration is approximately 1.6% by weight. Eight layers produce a cross-sectional area of 7 mm ² .

Example  2:

Example 2 describes the preparation of another Yb-Al-doped silica base material, and fibers drawn therefrom. The aerosol generator 12a is maintained at 950 占 폚. The primary He flow bubbled through the molten YbCl ₃ is set to 0.38 l / min and the secondary He flow to cool the saturated YbCl ₃ vapor in the cooler chamber 12.1 is set to 0.5 l / min. The above conditions for the aerosol generator are maintained for 1 hour before delivery to allow the system to reach equilibrium.

The MCVD system 16 is set up in a general manner and all steps before the deposition of the Yb-Al-doped silica are carried out using standard MCVD techniques with an aerosol three-way valve 13a set as a vent. For deposition of the Yb-Al-doped layer, the valve 13a is switched so that the aerosol enters the transfer tube and is mixed with the other precursor and process gas. SiCl ₄ maintains the bubble generator (12b) in 38 ℃. O ₂ 100 sccm is bubbled through the SiCl ₄ precursor. As in Example 1, Al ₂ Cl ₆ vapor is used as a precursor for Al and flows directly to the substrate tube 16.2 at a rate of 5 sccm. In addition to the precursor, 900 sccm of O ₂ and 200 sccm of He flow to assist oxidation and sintering, respectively. The precursor H ₂ / O ₂ torch described by crossing through the tube (16.2) is oxidized by heating the outer surface of the tube to 2,000 ℃.

A suitable number of cladding layers are deposited first. Subsequently, after the eight Yb-Al-doped core layers are deposited, the valve 13a is returned to the vent position, the pressure in the substrate tube is reduced, and the substrate tube containing the deposited layer is sealed . The relative index difference between the Yb-Al-doped and undoped regions of the base material is 0.006 and the Yb concentration is approximately 0.8% by weight. Eight layers produce a cross-sectional area of 7 mm ² .

The precursor core / clad geometry is then obtained to jacket the base material into a silica tube and draw it into the fiber to maintain single-transverse-mode operation at a pump wavelength of 975 nm.

An optical fiber with a Yb-Al-doped core zone prepared as described above exhibits significantly reduced photo-blackening than the best known commercially available fibers. More specifically, FIG. 3 compares two cases. Curves I - commercially available Yb-doped fibers promoted and sold as low photo-induced black fibers, and Curve II - YbCl ₃ - precursors were prepared using a standard MCVD system delivered as SCA in accordance with one embodiment of the present invention Yb-doped fibers.

Commercially available fibers (Curve I) lose about 8% of their original power after 1,000 seconds, but the fibers of the present invention exhibit four times better performance than the fibers, with only about 2% of their original power being lost at the same time intervals . As far as the present inventors are aware, the fibers of the present invention exhibit the best optical blackness characteristics of any high density Yb-doped silica fibers.

Alternative mode

It is to be understood that the arrangement described above is merely one example of many possible specific embodiments, and that the principles of the present invention may be applied based on this assumption. Numerous and varied other arrangements may be devised in accordance with the principles of the present invention without departing from the spirit and scope of the present invention by those skilled in the art.

In particular, there are many ways to form SCAs. It is desirable to rapidly cool the carrier gas stream saturated with the precursor vapor to cause supersaturation and alternately generate the precursor as homogeneous nucleate to form aerosol particles. Cooling may occur by conduction cooling, spin cooling, mixing, or adiabatic expansion (SK Friedlander, Smoke Dust and Haze, John Wiley & Sons, New York, NY, 1977 . However, chemical reactions can also be used to form aerosols. For example, RE chloride is reacted with oxygen at a temperature (e.g., 950 ° C) where RE chloride is vapor, as described above. At these high temperatures, oxides can form RE oxide aerosols. On the other hand, the negatively charged sphere, for example aluminum (Al), reacts with Cl ₂ to produce Al ₂ Cl ₆ vapor (for example at 350 ° C), which can then be cooled to form an aerosol The above description of the generator 12a in which the first chamber 12.2 is the reaction chamber).

It may also be advantageous to vaporize the aerosol particles before flowing into the working tube 16.2. As shown in Figure 3, the aerosol 12.0 flows into the tube 16.7 concentrically located within the supply tube 16.1. And the inner tube 16.7 is heated to an external heating source 16.9 near its end. The aerosol 12.0 is vaporized and then flows to the base material tube 16.2 as vapor (Fig. 1). Oxygen flows to the feed tube 16.1 to oxidize aerosols and vapors delivered to the delivery system of FIG. Alternatively, the oxygen can flow into the inner tube 16.7 and the aerosol can flow into the feed tube 16.1. (The primary purpose of the inner tube is to maintain the aerosol and oxygen, respectively, before the aerosol is pre-oxidized, ie, before the aerosol is vaporized.)

If the aerosol particles become larger for a higher charge mass, or if the aerosol particles aggregate too much (despite filtration) due to the longer transfer residence time and the fibers begin to exhibit undesirable signals of rare earth clustering, can do. When the heated tube 16.7 is not used, the particles are vaporized by oxidizing the particles prior to approaching or vaporizing the hot zone of the MCVD system forming the ideal (LVP vapor mixed with HVP vapor). If the particles are completely vaporized before being oxidized, the size of the delivered particles is important in terms of transport efficiency, but not in terms of optical properties of the fibers. There are some indications of what is happening with YbCl ₃ . However, RE-chloride particles can be first oxidized with other RE dopants, in which case the size of the particles can affect the size of the oxide particles, the size of which is important and needs to be as small as possible.

Instead of delivering the aerosol as a metal chloride to the deposition system, the aerosol may be delivered as an oxide. For example, any oxidant may be placed between each of the aerosol generators 12a, 12a 'and the deposition system 16. The upper chamber of the oxidizing agent is a bar to isolate the oxidation chamber 20, or simply as generator (12a) (O ₂ flows into the tube 24, and He is flowing into the tube 22) shown in Figure 1 (12.3 ). However, the oxides can have extremely low vapor pressures, which means that the oxide particles are not vaporized in the high temperature region of the substrate tube, and can be less homogenized in the deposited glass layer. Nevertheless, those skilled in the art will appreciate that, for example, when the use of an oxide improves the delivery of aerosol particles, or when the use of the oxides has only one method for forming an aerosol of a particular dopant, It will be appreciated that it is advantageous to deliver the aerosol as an oxide.

Finally, certain aspects of the aerosol process of the present invention are described and claimed as a method / apparatus for manufacturing an optical waveguide, and in the case of manufacturing an optical fiber, first of all the details of fabricating the base material and subsequently drawing the fiber therefrom Process. ≪ / RTI >

Multi-component  Aerosol

As described above, the aerosol used in the present invention may be SCA or MCA. In the case of MCA, each aerosol particle comprises two or more compounds containing a dopant or a precursor (e.g., chloride) of a host material and / or an oxide of a dopant or host material. For example, MCA includes particles wherein each particle is a composite of two (or more) RE dopant precursors, such as YbCl ₃ and ErCl ₃ . Alternatively, the MCA comprises particles wherein each particle is a composite of a RE dopant precursor and a non-RE LVP dopant, such as YbCl ₃ and Al ₂ O ₃ (alumina), respectively. MCA, on the other hand, includes particles in which each particle is a composite of an oxide of a RE dopant precursor (e.g. YbCl ₃ ) and an oxide of an HVP dopant (e.g. Ge ₂ O ₃ ) and / or an oxide of a host material (e.g. SiO ₂ ) .

The MCA aerosol may be generated using, for example, the generator 12a of FIG. Thus, the cooler secondary carrier gas of the generator 12a may contain seed particles suitable for initiating the condensation of the RE vapor. Alternatively, the seed particles may themselves be generated by another separate generator. In general, the seed particles are LVP precursor or oxide, for example, RE chloride, or may be alumina or, seed particles HVP oxide, e.g., SiO ₂ or Ge ₂ O _3, or a combination thereof, that is, Component seed aerosol.

In the latter case, the seed particles are preferably homogeneous blends of the respective aerosol components, which are advantageous in the production of homogeneous glass bodies, especially optical fibers.

Thus, in accordance with another aspect of the present invention, the present invention provides a method of making a glass body comprising a plurality of components, wherein at least one of the components is a first dopant having a first LVP precursor, wherein the vapor of the LVP precursor Providing a first aerosol comprising a first particle containing a first LVP precursor, comprising: (a) providing a first LVP precursor; and (a2) superposing the LVP vapor to form an aerosol; (B) generating the vapors of the other components separately; (C) convectively circulating the aerosol of step (a) and the vapor of step (b) to a vapor deposition system containing the substrate; And (d) forming on the surface of the substrate at least one doped layer comprising a vapor-containing dopant and a convectively circulated aerosol in step (c). In this aspect of the invention, the aerosol may be MCA or SCA.

The method can be carried out using the apparatus described above with reference to Figures 1-2.

The aerosol delivery system according to the present invention can easily handle LVP precursors such as RE precursors in a short period of time and can be used in conjunction with various glass deposition systems such as MCVD, OVD and VAD and can be used in conjunction with optical fibers and planar waveguides, The present invention can be applied to the manufacture of a glass body which also includes

Claims (52)

1. A method of making a glass body comprising a plurality of components and at least one component being a first dopant having a first LVP precursor, (A) generating a first aerosol comprising first particles of a first LVP precursor, each of the first particles comprising only a first LVP precursor of a first dopant, (B) the production step (a) and the production step (b) are carried out at a location remote from the deposition system used to form the glass body; (C) convection of the aerosol of step (a) and the vapor of step (b) from a location remote from the deposition system to a deposition system comprising the substrate, and (D) forming at least one doped layer on the surface of the substrate, the doped layer comprising a vaporized aerosol and vapor in step (c). 2. The method of claim 1 further comprising filtering the first aerosol to remove aerosol particles outside the specified range of sizes and to transmit only aerosol particles within the same size range, Characterized in that it is carried out by means of at least one part which does not contain any of the tubes used in the step (c) or the generator used in step (c). 3. The method of claim 2, wherein the filtering step removes particles outside the size range of 0.01 to 10 micrometers and allows only aerosol particles within the same range to permeate. 2. The method of claim 1, wherein the producing step (a) comprises heating the LVP precursor at a first temperature above room temperature, wherein the convection step (c) is conducted by passing the aerosol through a tube maintained at a temperature lower than the first temperature ≪ / RTI > comprising the steps of: The method of claim 1, wherein the generating step (a) (A1) providing an LVP precursor to a first chamber of the vessel, (A2) heating the LVP precursor to provide its vapor, (A3) flowing a carrier gas into the first chamber to produce a gas mixture containing the precursor in a second chamber of the vessel, Flowing a lower-temperature carrier gas into the second chamber to condense the vapor and form an aerosol of the precursor (a4); and ≪ / RTI > comprising the step of (a5) extracting the aerosol from the vessel. 6. The method of claim 5, wherein the carrier gas is saturated with the precursor. The method of claim 1, wherein the glass body is made of a planar waveguide. The method of claim 1, wherein the waveguide is fabricated as a silica optical fiber. 9. The method of claim 8, Wherein the deposition system comprises a MCVD system, the substrate comprises a substrate tube, the MCVD system comprises a supply tube axially coupled to the substrate tube and a concentric inner tube disposed within the supply tube, Characterized in that the convection step (c) comprises convection of the aerosol into one of the inner tube and the feed tube, and heating the aerosol before entering the substrate tube to convert it to a vapor state. Way. The method according to claim 1, Another component is a second dopant having a second LVP precursor, Further comprising the additional step of separately producing a second aerosol comprising second particles of a second LVP precursor and each of the second particles comprising only a second LVP precursor of a second dopant. A method of manufacturing a glass body. 11. The method of claim 10, further comprising the step of causing the first aerosol and the second aerosol to maintain parallel fluid flow delivery to each other. 11. The method of claim 10, further comprising mixing the aerosols of step (a) with each other before convection to the deposition system. 2. The method of claim 1, further comprising mixing the aerosols of step (a) with the vapor of step (b) prior to convection to the deposition system. 9. The method of claim 8, further comprising the additional step of forming a base material comprising at least one doped layer and withdrawing optical fibers from the base material. The method of claim 1, wherein the first LVP particles and the carrier gas are free of any organic compounds. The method of claim 1, wherein the first LVP precursor is chloride. 17. The method of claim 16, wherein the first particles are suspended in a carrier gas of He. 17. The method of claim 16, wherein the glass body is a Yb-doped optical fiber. 19. The method of claim 18, wherein the optical fiber comprises a Yb-doped region and the photodarkening of the optical fiber is reduced when the light beam is developed along at least the Yb-doped region. Way. The method of claim 1, wherein the first dopant is selected from the group consisting of Er, Yb, Nd, Tm, Ho and La. 2. The method of claim 1, wherein the deposition system oxidizes and vaporizes the precursor delivered to the system and is vaporized in the deposition system before the LVP precursor is oxidized. The method of claim 1, wherein the aerosol particles are oxidized prior to delivery to the deposition system. The method of claim 1, wherein the producing step (a) and the producing step (b) are equilibrated before the base material forming convection step (c). 2. The method of claim 1, further comprising the step of monitoring the size, number or both of the first particles generated in step (a) and controlling the operating parameters of step (a) corresponding to the monitoring step ≪ / RTI > The method of claim 1, wherein the glass body is made of a glass soot. 1. A method for producing MCVD of a silica optical fiber comprising a plurality of components and wherein at least one component is a first rare earth dopant having a first LVP precursor, (A1) providing a first LVP precursor in a first chamber of the vessel, heating the first LVP precursor to a temperature above room temperature to provide its vapor (a2), flowing the carrier gas into the first chamber (A3) generating a vapor of a carrier gas containing the first precursor in a second chamber of the vessel, flowing a lower temperature carrier gas into the second chamber to condense the vapor and to condense the first aerosol (A4) and a step (a5) of extracting a first aerosol from the vessel, wherein each first particle comprises a first LVP precursor of a first dopant, (A), < / RTI > (B) [producing step (a) and producing step (b) are carried out at a location remote from the deposition system used to form the optical fiber] (C) convection of the first aerosol and silica vapor from a location remote from the deposition system, through a tube maintained at room temperature or slightly higher temperature, to a MCVD system comprising a substrate tube, (D) forming a layer of silica doped from the vaporized aerosol particles and vapor in step (c) on the inner wall of the substrate tube; and And (e) disintegrating the substrate tube to form a fiber preform. 27. The method of claim 26 further comprising filtering the first aerosol to remove aerosol particles outside the predetermined range of sizes and to transmit only aerosol particles within the same size range, Characterized in that it is carried out by at least one part which does not contain any of the tubes used in the generator or convection step (c) used in the MCVD. 27. The method of claim 26 wherein the MCVD system comprises a supply tube axially coupled to a substrate tube and a concentric inner tube disposed within the supply tube, Wherein the convection step (c) comprises convection of the first aerosol into the inner tube and heating of the aerosol before entering the substrate tube to convert it to a vapor state. 27. The method of claim 26, wherein the first LVP precursor is chloride. 30. The method of claim 29, wherein the first particles are suspended in a carrier gas of He. 30. The method of claim 29, wherein the optical fiber is a Yb-doped optical fiber. 32. The method of claim 31, wherein the optical fiber comprises a Yb-doped region, and the optical blackening of the optical fiber is reduced when the light is developed along the Yb-doped region. 27. The method of claim 26, wherein the first LVP particles and the carrier gas are free of any organic compounds. 1. A method of making a glass body comprising a plurality of components and wherein at least one component is a first dopant having a first LVP precursor, Providing a vapor of an LVP precursor (a1) and supersaturated LVP vapor to form an aerosol (a2) to produce a first aerosol comprising first particles comprising a first LVP precursor a), (B), separately producing steam of the other components, (C) convection of the aerosol of step (a) and the vapor of step (b) to a vapor deposition system comprising a substrate, and And (d) forming at least one doped layer from a dopant contained in the vapor and an aerosol convected in step (c) on the surface of the substrate. 35. The method of claim 34, wherein step (a2) comprises flowing a primary carrier gas through the LVP vapor to accompany the LVP vapor, and condensing the accompanying vapor to form an aerosol. ≪ / RTI > 36. The method of claim 35, comprising flowing a lower temperature secondary carrier gas through the vapor accompanied by the condensation step. 35. The method of claim 34, wherein step (a1) causes a reactive gas to flow onto the negatively charged phase of the LVP precursor causing a chemical reaction to produce the LVP precursor vapor. 38. The method of claim 37, wherein the negatively charged spherical body comprises a metal body, wherein the metal comprises a first dopant. 35. The method of claim 34, wherein step (a2) comprises rapidly cooling the LVP vapor. 35. The method of claim 34, wherein step (a2) adiabatically expands the primary carrier gas and the LVP vapor to condense the LVP vapor. 35. The method of claim 34, wherein the first LVP particles and the carrier gas are free of any organic compounds. 35. The method of claim 34, wherein in step (a2) the first LVP precursor is condensed onto the seed aerosol. 43. The method of claim 42, wherein the seed aerosol comprises an LVP material. 44. The method of claim 43, wherein the seed aerosol is selected from the group consisting of an RE precursor aerosol and an alumina aerosol. 43. The method of claim 42, wherein the seed aerosol comprises an aerosol of an oxidized HVP compound. 46. The method of claim 45, wherein the HVP compound is selected from the group consisting of a dopant and a host material. 47. The method of claim 46, wherein the seed aerosol comprises a homogeneous multicomponent oxide comprising at least two HVP compounds. 35. The method of claim 34, wherein the producing step (a) and the producing step (b) are performed at a location remote from the deposition system used to form the glass body, and the convection step (c) Wherein the vapor of the production step (b) is transferred to a deposition system from a location remote from the deposition system. 35. The method of claim 34, further comprising the additional step of filtering the first aerosol to remove aerosol particles outside the specified range of sizes and to transmit only aerosol particles belonging to the same size range, characterized in that it is carried out by at least one part which does not contain any of the tubes used in step (c) or the generator used in step a) or convection step (c). 47. The method of claim 46, wherein the filtering step removes particles outside the size range of 0.01 to 10 占 퐉 and allows only aerosol particles within the same range to permeate. 35. The method of claim 34, further comprising the step of monitoring the size, number or both of the first particles generated in step (a) and controlling the operating parameters of step (a) corresponding to the monitoring step ≪ / RTI > A container having a first chamber and a second chamber fluidly fluidly transferred to each other (the first chamber is designed to contain LVP material) A heater designed to heat the LVP material, A first inlet designed to flow a primary gas into the first chamber to produce a vapor compound in the second chamber comprising at least one element of the LVP material, A second inlet designed to flow a cooler carrier gas into the second chamber to condense the vapor and form an aerosol therefrom; and An aerosol generator comprising an outlet designed to extract an aerosol from a vessel.

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