KR20070064404A - Apparatus and method for fabricating glass bodies using an aerosol delivery system - Google Patents

Abstract

A method of fabricating glass bodies containing an LVP(low vapor pressure) precursor dopant such as rare earth elements is provided to manage an LVP precursor without defects of typical liquid aerosol systems, to be applied to MCVD system or other optical fiber production systems such as OVD and VAD by filtering aerosol particles with size out of the desired range. The method includes the steps of: (a) forming first aerosol which contains first particles of first LVP precursor, the first particles only having the first LVP precursor; (b) generating vapor form of ingredients (wherein (a) and (b) steps are performed far from a vapor deposition device to form a glass body); (c) conducting convection of the aerosol and the vapor from (a) and (b) steps to the vapor deposition device containing a substrate; and (d) forming at least one doped layer, which contains the dopant of the aerosol and the vapor after the convection, on the surface of the substrate.

Description

Apparatus and method for fabricating glass bodies 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 partially isometric view illustrating an apparatus for making rare earth (RE) -doped optical fibers 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 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. FIG. The heaters 12.4a and 12.4b of part A are shown illustratively.

3 is a partial isometric view of a feed tube having a concentric inner tube embedded to vaporize before the aerosol is introduced into the MCVD matrix tube in accordance with another aspect of the present invention.

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

Cross Reference to Related Application

This application is filed on December 16, 2005 and is pending. US Provisional Patent Application No. 60 / entitled "Aerosol delivery method for optical fiber and fiber preform fabrication". Claims priority on 750,966.

Field of invention

FIELD OF THE INVENTION The present invention relates to glass bodies (eg, optical fibers, planar waveguides, glass soot), and more particularly to apparatus and methods for making rare earth (RE) doped optical fibers.

Discussion of related technologies

In standard MCVD techniques for making optical fibers, the substrate is made by flowing a relatively high vapor pressure (HVP) precursor glass (eg, SiCl ₄ , GeCl ₄ and POCl ₃ ) and oxygen down a rotating silica substrate tube. An external hydrogen-oxygen torch slowly crosses the tube length to locally heat the small compartment of the tube. The gas stream, which travels much faster than the torch, is heated as it approaches the torch compartment, causing the precursor to be hot enough to react with oxygen to form oxide aerosol particles. These particles colloid and coalesce with each other to increase in size. As the gas stream leaves the torch compartment, it remains hot relative to the tube wall. Due to this temperature gradient between the tube and the gas stream, aerosol particles travel along the tube wall and deposit on the tube wall to form a soot layer. As the torch passes through this soot layer, the soot is sintered and converted to a solid glass layer. The process is repeated to deposit a number of glass layers on the inner wall of the tube, for example hundreds of layers can be deposited to produce a core of conventional silica fibers, but typically a smaller number of layers (e.g. For example, 3 to 15 layers) are deposited to produce a RE-doped fiber core. After layer deposition is terminated, the tube is heat collapsed to form a solid rod known as a preform. Standard techniques are used to withdraw optical fibers from the substrate.

Not all suitable dopants can be delivered using this standard MCVD method because no suitable HVP precursor is present. Suitable precursors should have a relatively high vapor pressure (about 1 torr or more at room temperature) and contain no chemicals (eg hydrogen, water) that will adversely affect the properties of the deposited glass. Some preferred dopants such as RE elements (particularly erbium (Er) and ytterbium (Yb)) have low vapor pressure (LVP) precursors and cannot be delivered using convenient vapor phase approaches such as standard MCVD.

To solve this problem, several manufacturing methods using LVP RE precursors have been developed in the prior art, but they all have significant limitations. Below is a brief description of the most common methods and their most significant limitations.

Solution Doping Method : The soot layer is deposited on the inner wall of the substrate tube using a standard dopant, 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 that retains 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. The solution doping method has the following limitations: (i) the reproducibility of the LVP dopant concentration is poor depending on the base material; (ii) the amount of liquid held by the soot layer depends on porosity, which is very difficult to control; (iii) The process is very time consuming, taking 1-2 hours per deposited glass layer compared to about 10 minutes required for a standard MCVD glass layer.

Chelating method : A base material is manufactured using the chelate precursor of RE element. Chelates are large organo-metallic compounds with relatively high vapor pressures. Chelate processes have the following limitations: Chelates contain undesirable elements, such as hydrogen, and to date have not produced glass with the purity required for high quality optical fibers.

Vapor Delivery Method : An ampoule containing the desired LVP RE precursor is placed inside an MCVD substrate tube. The ampoule is heated to a temperature high enough to achieve the required vapor pressure using an external heating source (eg flame or furnace). See US Pat. No. 4,666,247, issued to MacChesney, JB, et al., May 19, 1987, which is incorporated herein by reference. The ampoule approach has the following limitations: (i) The precursor vapor pressure (and its delivery rate) is very sensitive to temperature, which is very difficult to control because the external heating source heats the RE source material disposed in several concentric glass tubes. ; (ii) flowing the gas stream cools the tubes, which leads to uncertainty of the actual heating source temperature; (iii) There is only a small surface area between the precursor and the carrier gas so that the precursor will not be saturated in the carrier gas. This changes the amount of precursor delivered when the surface size changes or the surface is covered by, for example, an RE oxide layer; (iv) When the precursor leaves the ampoule, some or all of the precursor reacts with the surrounding oxygen to form metal oxide aerosol particles. The size of these aerosol particles is not controlled. If large particles are formed, current techniques suggest that they form clusters that can be detrimental to RE-doped substrates and fibers.

Liquid Aerosol Delivery Method : A solution containing organo-metallic precursors for all dopants desired for organic solvents is sprayed into the liquid aerosol (droplets) and delivered 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 onto the substrate tube as a soot layer. Care is taken not to sinter the soot layer. Two documents, which are incorporated herein by reference: TOMorse, et al., J. Non-Crystal. Solids, Vol. 129, pp. 93-100 (1991); And J. Aerosol Sci., Vol, 22, No. 5, pp. 657-666 (1991). See Morse et al., J. Non-crystal. Solids, supra at page 96, column 2], "The solution must contain all the components of the glass structure in each aerosol particle to ensure microscopic uniformity to minimize crystalline inclusions in the glass" (underlined "each "And" all "are not in the literature but are added for emphasis). The phrase “all components” includes, for example, precursors of standard HVP dopants (eg Ge and / or P) as well as certain LVP RE elements (eg Nd and / or Er). This liquid aerosol approach has the following limitations: (i) the solution is flammable and can explode; (ii) a new solution must be prepared each time a different glass composition is required; (iii) the process is time consuming; And (iv) the process is not expected to have a very low glass loss as long as the reaction product contains not only contaminants such as H ₂ O and H ₂ , but also the preferred free oxides.

Accordingly, it would 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 would also be desirable to provide a delivery system that can be applied to MCVD systems as well as other optical fiber manufacturing systems such as OVD and VAD.

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

[Simple summary of invention]

In accordance with one aspect of the present invention, Applicant is directed to a glass body (eg, optical waveguide) comprising a plurality of components, wherein at least one component is a first dopant (eg, RE element) having a first LVP precursor. , A waveguide or a glass soot on the surface. The manufacturing method of the said glass body,

(A) producing a first single component aerosol (SCA) from the LVP precursor (ie each first aerosol particle comprises only the LVP precursor of the first dopant),

Step (b) of separately generating steam of the other components (the step of producing (a) and (b) is carried out at a location remote from the deposition system used to form the glass body),

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

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

In one aspect, the glass body comprises a second dopant having a second LVP precursor and the method includes a second single component aerosol (SCA) from the second LVP precursor (ie, each second aerosol particle is a second dopant). And only includes LVP precursors). The two aerosols can be kept separate from each other while convection to the deposition system. Alternatively, they may be mixed with each other and / or vapor of other components, which may then be convection to the deposition system.

According to another aspect of the present invention, the applicant,

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,

Generating a first aerosol comprising first particles comprising a first LVP precursor, including providing a vapor of the LVP precursor (a1) and supersaturating the LVP vapor to form an aerosol (a2) a),

(B) separately generating vapors of other components,

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

Claimed is a method of making a glass body, comprising the step (d) of forming at least one doped layer comprising aerosol convection in step (c) and a dopant contained in vapor on the surface of the substrate.

According to another aspect of the present invention, an aerosol generator comprises a container having a first chamber and a second chamber fluidly coupled to each other. In one aspect, the first chamber is a bubbler chamber and the second chamber is a condenser chamber. The heater surrounds the first chamber to keep its temperature essentially constant. The primary carrier gas is supplied to the bubbler chamber through the first inlet, and the colder secondary carrier gas is supplied to the condenser chamber through the second inlet. The outlet is coupled to the condenser chamber. In operation, the precursor (usually a solid at room temperature) is placed in a bubbler chamber and heated to a relatively high temperature sufficient to liquefy the precursor and obtain the desired vapor pressure of the precursor. The primary carrier gas convections the precursor vapor from the precursor liquid into the condenser chamber (preferably, the precursor vapor completely saturates the primary carrier gas). Since precursor vapor cannot be delivered at this high temperature (ie, precursor vapor will condense on the walls of the standard tubes used to deliver the vapor to the deposition system), the colder secondary carrier fed into the second inlet Cool by gas quickly. As a result, the aerosol of the precursor is formed in the chamber upon condensation and extracted through the outlet. The aerosol can be delivered through a standard tube without significant aggregation or deposition at room temperature or slightly higher, thereby allowing the aerosol to convex with the standard vapor species into a standard deposition system.

In another embodiment, the first chamber is a reaction chamber. In this case, a sub-precursor is placed in the first chamber, and the primary gas is a gas that reacts with the precursor to produce the precursor compound in vapor form. The vapor convection into the condenser chamber, the colder 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 invention can be applied to a method of making a glass body on a substrate. The glass body may take the form of a glass soot layer that is deposited on the surface of the heated substrate and then sintered to form the glass layer. Such glass layers 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 that is intentionally deposited on a heated substrate and not sintered but instead flows to a suitable collector (eg, the glass soot acts as an unheated substrate). Collected on the surface of the vacuum bag). Such a soot 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 includes one or more dopants having LVP precursors. Such dopants include RE-elements such as Er, Yb, Nd, Tm, Ho and La, or mixtures thereof, as well as aluminum (Al) and alkaline earth metals such as Be, Mg and Ca.

By way of example, the present invention can be applied to the manufacture of optical fibers by MCVD, which deposits a soot glass layer on the inner surface of a heated substrate tube, sinters the layer, collapses the tube into the substrate, and light from the substrate. Drawing the fibers together. In addition, the present invention can be applied to the production of optical fibers made of VAD and OVD, which requires the soot glass layer to be deposited on the outer or distal surface of the rotating cylinder, the soot layer is sintered and the optical fiber drawn out of the substrate. do. In contrast, the present invention can also be applied to the manufacture of planar optical waveguides, which involves depositing a glass layer on the major surface of the planar substrate. For simplicity and illustrative purposes only, the following description focuses on the manufacture of optical fibers using heated substrate tubes.

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

Single ingredient aerosol

According to one aspect of the present invention, as shown in FIG. 1, an apparatus 10 for manufacturing an optical fiber includes various components of the optical fiber (eg, a host material such as silica, the LVP dopant described above, and Ge and P). And a plurality of precursor sources 12 to produce precursors of standard HVP dopants). Source 12 contains one or more aerosol generators 12a that provide an SCA of LVP precursors such as RE chloride. (A separate aerosol generator, denoted by omission 12a ', may be used to generate an SCA of another LVP precursor.) In addition, the source 12 may include one or more conventional vapors that provide vapors of other fiber components. Generators (or bubblers) 12b, 12c, 12d, generally containing ones having HVP precursors (e.g. chlorides of Si, Ge and PO).

Source 12 is located far from glass-layer deposition system 16. By way of example, precursor sources 12 are connected in parallel with each other in fluid-flow delivery, or in series fluid-flow delivery with deposition system 16. Those skilled in the art will appreciate that system 16 may be, for example, an MCVD system, an OVD system, a VAD system, or any other deposition system compatible with the precursor delivery system of the present invention. For illustrative purposes only, the following description assumes that the deposition system 16 is a standard MCVD system.

Thus, the MCVD system 16 generally contains a feed tube 16.1, a substrate tube 16.2, and an outlet tube 16.3 arranged in series with each other. The feed tube, substrate tube and discharge tube rotate in the direction of arrow 16.4 around their common longitudinal axis, and the heating source (i.e. torch) 16.5 moves in the direction of arrow 16.6 along the longitudinal axis to move the substrate tube. Heat. Vapor and aerosol precursors enter feed tube 16.1 through a standard rotary union (not shown). The combination causes the feed tube to rotate in the MCVD lathe with the delivery tube 18 stationary. The aerosol precursor can be delivered to the system 16 as a vapor precursor using the same port, or can be delivered through a separate port. The inventors have found that it is convenient to deliver the aerosol precursor using its own port. In addition, the inventors have found that it is desirable to deliver the vapor precursor through the ports on the feed tube and shaft so that a minimum amount of tube bending is required. The design also allows the concentric tubes to be easily located in the feed tube 16.1 as shown in the tube 16.7 in the embodiment of FIG. 3.

“Delivery” means generating a precursor and transferring the associated gas from generator 12 to deposition system 16 through a conduit system (eg, 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 base tube collapses into the base material, and the base material is drawn out to the optical fiber.

Multiple sources 12 contain one source 12 for each component of the optical fiber to be formed. For example, to produce doped silica optical fibers with RE, Ge, and P, the aerosol generator 12a provides an SCA of an RE precursor (e.g., RE-chloride, such as ErCl ₃ or YbCl ₃ ), and a vapor generator ( 12b) provides a vapor of a silica precursor (eg SiCl ₄ ), vapor generator 12c provides a vapor of a Ge precursor (eg GeCl ₄ ), and steam generator 12d provides a P precursor (eg POCl _3). To provide steam.

Generally, the carrier gas used in precursor source 12 should be inert (e.g. He, Ar), advantageous in the manufacture of high quality glass (e.g. O ₂ ), or for other processing reasons that do not have a detrimental effect on the fiber. Useful (e.g. N ₂ , Cl ₂ ). In the aerosol generator 12a, He is generally used because it helps to minimize bubble formation during sintering. On the other hand, O ₂ is generally used in generators (bubble generators) 12b, 12c, 12d. (Because the bubbler is kept at a relatively low temperature (eg below 100 ° C.), the metal chloride precursor is not oxidized in the bubbler.)

Although not shown, the addition of a carrier gas (eg He, O ₂ ) that can be coupled directly to the delivery system, ie not connected via aerosol generator 12a or bubble generators 12b, 12c, 12d. Sources of (i) and / or additional sources of dopant gases (eg SiF ₄ ) that are vapor at room temperature are well known to those skilled in the art, and thus a bubbler does not have to generate the necessary vapor pressure.

Importantly, the aerosol generators 12a and 12a 'are high enough to allow LVP dopants (e.g., RE dopants) to be transferred to the MCVD system at low temperatures and maintain standard deposition rates.

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 (eg, exponentially rising dopants such as Ge and P), the precursors are generally heated to 30-50 ° C. (eg 38 ° C.). Moreover, in dopants derived from LVP precursors (e.g., RE dopants such as Er and Yb), the temperature is generally much higher to 800 to 1,100 ° C (e.g., 900 ° C for precursor ErCl ₃ ; 950 ° C for YbCl ₃ ). Some are severe. However, the tube 18 connecting the generator to the MCVD system 16 is generally at a much lower temperature than the LVP dopant source in the generator 12a [eg, 50-100 ° C .; Maintained by a heater (also known but not shown), and the hot LVP precursor gas is concentrated and deposited on the inner wall of the tube, so that the hot gas can be transferred to the MCVD system through a significantly lower temperature tube. Can't. The solution to the above problem is to produce the LVP fiber component as an aerosol that can be delivered to the MCVD system 16 through a tube 18 maintained at or slightly above room temperature. In all cases, if the aerosol is mixed with HVP vapor as shown in FIG. 1, the tube 18 is at a temperature higher than the temperature of the hottest bubbler 12b, 12c, 12d (eg 38 ° C.) (eg 70). ℃). On the other hand, if the aerosol is not first mixed with the HVP vapor and delivered directly to the deposition system 16, all the tubes connected to the output of the aerosol generator (eg 12a) may be present at room temperature.

Although the present invention is not bound by the following process theory, the inventors believe that the following phenomenon will occur. When the RE chloride aerosol enters the hot zone of an MCVD system that is also supplied with oxygen, most of the aerosol is vaporized with RE chloride vapor. The vaporized RE chloride (gas) molecules then oxidize the formed RE oxide molecules, which collide with other oxide molecules (eg SiO ₂ molecules) and deposit as soot inside the walls of the substrate tube. After sintering, the process forms a very homogeneous glass. Importantly, the present invention allows for independent control of two important processes (dopant delivery and oxidation). In an aerosol generator, a process is set up to produce particles that have a predetermined (eg, optimal or near optimal) size range and allow the desired LVP dopant concentration to be delivered to the headstock tube with low loss. As the aerosol particles reach the high temperature region, it is believed that as most of them vaporize into their respective molecules, they lose information about their previous size as particles. In the high temperature region, these vaporized molecules are oxidized. Conditions in the high temperature region can be set (eg optimized or nearly optimized regardless of all aerosol generator conditions) such that all dopants react together to form an essentially homogeneous glass.

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

Aerosol Particle Size

The size of the aerosol particles is preferably in the range of approximately 0.01 μm to 1.0 μm. On the other hand, particles of 10 μm can be delivered, if necessary, but care must be taken to minimize the distance between the aerosol generator and the substrate tube. When the particles are significantly larger than 1 μm, the particles may settle on the inner wall of the delivery tube due to their weight. When the particles are significantly smaller than 0.01 μm, they can deposit on the tube wall due to Brownian motion. In one aspect of the invention, large particles are removed during delivery, in most cases large particles create clusters in RE-doped fibers, and clusters are undesirable processes, for example, frequency up (up). -conversion), which is quite advantageous.

Although some RE-aerosol particles are originally removed from the tube 18 or other components of the delivery system (eg, condensation chamber 12.1 (described below)), this type of particle filtration process is not easily controlled. Thus, according to one aspect of the present invention, the particles pass through the filter 14, and the filter 14 is positioned between the aerosol generators 12a, 12a ′ and the deposition system 16. The filter may contain well known diffusion batteries to remove small particles (eg, particles of 0.01 μm or less). In addition, to remove large particles (eg, particles larger than 1.0 μm), filter 14 may have a well-known cyclone, or some bend (eg, coil), depending on how effectively the user wants to remove large particles. It may contain a series of tubes, or settling chambers.

The collection efficiency of a 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 the YbCl ₃ particles in He flowing through four tubes with internal diameters of 1.5, 2, 3 and 4 mm, each tube has two and a half loops. The collection efficiencies of the different diameter coils for the particles of 1.0 μm are about 92%, 65%, 27% and 12%, respectively, and for the particles of 1.4 μm the corresponding efficiencies are about 99%, 84%, 48%, and 26% and the corresponding efficiencies for the 2.0 μm particles are about 100%, 100%, 72%, and 42%, respectively. Thus, small diameter (1.5 mm and 2 mm) tubes collect almost all of the particles having a size of about 2 μm or more, while diameters until the particle size reaches about 4 μm (3 mm tube) and are at least 5 μm (4 mm tube) These large (3mm and 4mm) tubes collect almost no particles. See DYH Pui et al., Aerosol Sci. and Tech., Vol. 7, pp. 301-315 (1987).

Aerosol particle size is typically controlled by particle impingement and fusion time, which is described in more detail below in connection with the description of the aerosol generator 12a of FIG. 2.

Since aerosol particle size is important for effective delivery of LVP dopants, the size and / or number of particles delivered to the deposition system can be monitored and, in response, the operation of generators 12a, 12a 'and / or filter 14. It may be advantageous to include the feedback subsystem 30 in the delivery system to control the parameters. As shown in FIG. 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 signal generated by the sensor 30.1 and sends a control (e. G. Error) signal to the controller 30.3, which in turn sends 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. The above components contain a mass flow controller that controls the flow rate of the various gases and / or a heater that controls the temperature (s) of the aerosol generator 12a.

The monitor 30.2 may, for example, contain 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 schematic of the aerosol generators 12a, 12a 'is shown in FIG. According to this aspect of the invention, the aerosol generators 12a, 12a 'comprise a container 12.1, a first chamber 12.2 and a second chamber 12.3 connected in fluid-flow delivery to each other. In one embodiment, the first chamber is a bubbler chamber 12.2 located in the first (eg lower) portion and the second chamber is a cooler chamber 12.3 located in the second (eg upper) portion. The bulbous zone 12.S is connected to the bottom of the bubbler chamber 12.2. The first heater 12.4a surrounds the lower part, ie both the bubbler chamber 12.2 and the bulbous zone 12.8. The first inlet 12.5 allows the primary carrier gas (eg He) to be supplied through the tube 22 to the bulbous zone 12.8 and the second inlet 12.6 is the cooler second carrier gas (eg Allow room temperature He) to flow through the tube 24 into the cooler chamber 12.3. Preferably, the second heater surrounds all parts (or equivalent parts) of the cooler chamber 12.3. The second heater 12.4b maintains the cooler chamber 12.3 at a lower temperature than the bubbler 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 via an outlet 12.7.

Although the above description suggests that the bubbler chamber 12.2 and the cooler chamber 12.3 are located at the bottom and top of the generator 12a, respectively, those skilled in the art will appreciate that the two chambers may be divided into different portions (e.g., Will be located side to side).

In the process, the precursor zone 12.8 is charged with high purity LVP precursor solids 12.9 (e.g., 6 to 9 pure RE-chlorides commercially available), and the solids are liquefied to obtain the desired vapor pressure. Heating to a relatively high temperature (eg 800-1100 ° C.) sufficient to The primary carrier gas bubbles through the liquefied precursor, withdrawing the precursor vapor from the precursor liquid (hot zone) to the cooler chamber 12.3 (cold zone). (Preferably, the precursor vapor sufficiently saturates the primary carrier gas in the global zone 12.8.) However, in the cooler chamber 12.3, which is maintained at a significantly low temperature (eg 500 ° C.), the precursor vapor is supersaturated. . As a result, an RE aerosol 12.0 is formed in the cooler chamber 12.3 and exits the vessel through the outlet 12.7. The outlet port is in fluid-flow transfer with the MCVD system 16 via an outlet tube 26 and a delivery tube 18 (FIG. 1) that are maintained at room temperature or slightly above room temperature. More specifically, to prevent the HVP precursor from condensing in the tube during delivery, the tube 18 is slightly less than the highest temperature of the HVP bubbler (eg, 38 ° C. for the SiCl ₄ bubbler 12b in the embodiment of FIG. 1). It must be heated to high temperatures (eg 70 ° C). As mentioned above, depending on the delivery system design, the aerosol can be delivered at room temperature or slightly above room temperature. Once the aerosol reaches the high temperature region 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 aspect 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 sub-precursor to vaporize the precursor compound (eg Al ₂ Cl ₆ ) in vapor form. Gas to be produced (eg Cl ₂ ). The steam is convection circulated to the cooler chamber, a lower temperature secondary carrier gas (eg, He) is flowed through the cooler chamber and the aerosol is formed in the manner described above.

In some embodiments, the vapor convection circulated to the second (cooler) chamber 12.3 contains one or more chemical elements derived from LVP material (precursor or subprecursor), which element ultimately forms a dopant in the formed glass body. do. The connection between precursor source 12 and MCVD system 16 is illustratively controlled by three-way valves 13a-d. Each valve has an off vent and run position. As shown, the valve is in the vent position to allow the generator to continue to move and deliver the precursor to the MCVD system 16 only when necessary. This feature reduces fluctuations at startup. When the device 10 is ready to deliver the precursor aerosol to the MCVD system 16, the preselected valve is rotated to its run position, which places the corresponding selected source 12 in fluid-flow delivery with the system 16. Let's do it.

As described above, aerosol particle size is typically measured by particle collision and fusion time. The impact time, which depends on the volume fill (aerosol volume per carrier gas volume), depends on the temperature of the heater 12.4a (ie, the temperature of RE chloride (12.9)), the flow rate of the primary carrier gas into the tube 22 and the dilution gas. Control at the flow rate to the tube 24. The fusion time, on the other hand, is the temperature of the heater 12.4b (ie, the temperature of the cooler chamber 12.3), the ratio of the cooler chamber not surrounded by the heater 12.4b, the shape of the cooler chamber outlet 12.7, the dilution gas It is controlled by 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, for example 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 for a relatively long time (e.g. long residence time) when the carrier gas is bubbled in contact with the precursor. The ability to produce (large surface-to-volume ratio) allows precursor vapors 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 settling time between MCVD substrates, such as substrates made only with HVP dopants. (3) The aerosol generator of the present invention is independent of the other parts of the system. This feature allows any number of aerosol generators (many latent dopants) to be added to the deposition system. (As mentioned above, the aerosol generators are exemplarily added in parallel or in series.) Furthermore, the delivery system of the present invention, and thus the entire fiber production system incorporating the delivery system, is a system operator or device. 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 is more clearly known than the prior art approach. Moreover, the three-way switch ensures that the LVP precursor generator (and standard bubble generator) of the present invention always reaches equilibrium. (The precursor vapor pressure does not change significantly over time.)

Operating conditions

This paragraph describes exemplary operating conditions for MCVD fabrication of Yb-doped optical fibers in accordance with one aspect of the present invention. Aerosol generator 12a contains precursor YbCl ₃ . The amount of YbCl ₃ and the shape of the generator causes YbCl ₃ to reach its equilibrium vapor pressure when the primary He flow through the tube 22 flows (bubble) through the tube 22. The standard operating temperature of the generator is 950 ° C., however, if a high or low aerosol volume fill is desired, it can be raised or lowered as desired (eg 800 ° C. to 1100 ° C.). As described above, there are generally cases where two Hes flow through the tubes 22, 24 to the aerosol generator 12a. The primary He flow through the tube 22 flows to the bottom of the bulbous zone 12.8 that is bubbled through liquefied YbCl ₃ (12.9). Optionally, but preferred, the tube 24, the second He flow through the room temperature to 950 ℃ (example: 500 ℃) occurs and cool the saturated YbCl ₃ vapor from, a condenser chamber (12.3 to supersaturation to form an aerosol of YbCl ₃ vapor Flow). Secondary He flow also dilutes the aerosol volume fill. In general, the total flow rate (bubbling volume and dilution amount) 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. The general range is about 0.2-1 l / min, but higher or lower flow rates can be used.

The temperature of the heaters 12.4a and 12.4b and the flow rate of the He Kaer gas are set before the start of the run so that the system runs at equilibrium conditions. During startup or whenever no YbCl ₃ aerosol is 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 up and operated in a standard manner. Assuming a non-Yb doped glass layer is desired, for example in fiber cladding, the layers are made with a closing valve 13a, otherwise using standard MCVD techniques. By way of example, Yb doping is present only in the fiber core and the Yb distribution is essentially radially uniform. At the end of the last cladding layer, switch valve 13a is turned on so that YbCl ₃ aerosol flows into the delivery tube. The aerosol flows into the rotating seal with all of the other selected vapor dopants. For example, SiCl ₄ and GeCl ₄ are selected by turning on the valves 13b and 13c and turning off the valve 13d. Soot is formed, deposited and sintered inside the walls of the substrate tube 16.2 using standard MCVD methods and temperatures. No further purification process is 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 to 13d, respectively. The pressure in the substrate tube 16.2 decreases, and the tube 16.2 collapses to the substrate using standard MCVD techniques. Subsequently, the base material is drawn back to a suitable length of optical fiber using standard fiber drawing techniques.

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

Five or more cores are generally passed through so that the corresponding five or more RE-doped core layers are deposited (heating source 16.6 along substrate tube 16.2 is switched). Of course, more than five or less than five layers can be deposited.

Suitable tubes for delivering aerosol and vapor from the generator 12 to the rotating chamber contain Teflon tubes 18 with an outer diameter of 3/8 inch. Suitable sedimentation chambers (as any filter 14) for filtering large YbCl ₃ particles include a tube with an internal diameter of 3 inches, which reduces the flow rate sufficiently to allow large particles to settle out of the carrier gas stream due to weight. Let's do it.

In yet another embodiment, the process of the present invention does not use any organic compounds (such as solvents or precursors), and by itself is also an undesired contaminant (such as a byproduct of the use of such compounds of the prior art). : 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 further purification steps to remove the above contaminants.

Example

These examples describe the preparation of Yb-doped silica optical fibers. 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 noted. In these embodiments, YbCl ₃ is the LVP precursor of Yb and Yb is used as a dopant in silica fibers. (Yb is actually incorporated into the fiber as an oxide, but as is well known in the art, it is the Yb element that changes the particle properties of the doped silica.) The settling chamber is used as the filter 14.

Example  One:

Example 1 describes a Yb-AI-doped silica matrix prepared according to the present invention. YbCl ₃ aerosol generator 12a is maintained at 975 ° C. to achieve high concentrations 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-AI-doped silica soot layer are performed using standard MCVD techniques with an aerosol three-way valve 13a set to vent. For the deposition of the Yb-AI-doped layer, the valve 13a is switched so that the aerosol enters the delivery tube and mixes with other precursors and process gases (eg, He, O ₂ ). SiCl ₄ bubbler 12b is maintained at 38 ° C. 100 sccm of O _{2 is} bubbled through the SiCl ₄ precursor. Al ₂ Cl ₆ vapor is used as precursor for Al (incorporated as oxides in silica) and flows directly into substrate tube 16.2 at a rate of 6.7 sccm. In addition to the precursors, 900 sccm of O ₂ and 400 sccm of He are flowed to assist oxidation and sintering, respectively. The precursor is oxidized by traversing the H ₂ / O ₂ torch 16.5 through the substrate tube 16.2 to heat the outer surface of the tube to 2,100 ° C.

A suitable number of cladding layers are first deposited. Subsequently, after eight Yb-AI-doped core layers have been deposited, return valve 13a to the vent position, reduce the pressure in the substrate tube, and seal the substrate tube containing the deposited layer in a conventional manner. To collapse. The relative index difference between the Yb-Al-doped zone and the undoped zone of the base material is 0.007 and the Yb concentration is approximately 1.6% by weight. The eight layers produce a cross section area of 7 mm ² .

Example  2:

Example 2 describes the production of another Yb-AI-doped silica matrix, and fibers drawn therefrom. The aerosol generator 12a is maintained at 950 ° C. 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 prior to the deposition of Yb-AI-doped silica are performed using standard MCVD techniques with an aerosol three-way valve 13a set to vent. For the deposition of the Yb-AI-doped layer, the valve 13a is switched on so that the aerosol enters the delivery tube and mixes with other precursors and process gases. SiCl ₄ bubbler 12b is maintained at 38 ° C. 100 sccm of O _{2 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 into the substrate tube 16.2 at a rate of 5 sccm. In addition to the precursor, O ₂ 900sccm and He 200sccm are flowed to assist oxidation and sintering respectively. The precursor is oxidized by crossing the H ₂ / O ₂ torch through the substrate tube 16.2 to heat the outer surface of the tube to 2,000 ° C.

A suitable number of cladding layers are first deposited. Subsequently, after eight Yb-AI-doped core layers have been deposited, return valve 13a to the vent position, reduce the pressure in the substrate tube, and seal the substrate tube containing the deposited layer in a conventional manner. To collapse. The relative index difference between the Yb-Al-doped zone and the undoped zone of the base material is 0.006 and the Yb concentration is approximately 0.8% by weight. The eight layers produce a cross section area of 7 mm ² .

The base material is then jacketed with a silica tube and drawn into a fiber to obtain accurate core / clad geometry to maintain single-cross-mode operation at a pump wavelength of 975 nm.

Optical fibers with Yb-AI-doped core zones, prepared as described above, exhibit reduced light blackening significantly lower than the best known commercially available fibers. More specifically, FIG. 3 compares the two cases. Curve I-a commercially available Yb-doped fiber promoted and sold as low photoblackened fiber, and curve II-YbCl ₃ -precursor prepared using a standard MCVD system in which it is delivered as SCA according to one aspect of the present invention. Yb-doped fibers.

A commercially available fiber (curve I) loses about 8% of its original power after 1,000 seconds, but the fiber of the invention is four times better than the fiber with only about 2% of its original power lost at the same time interval. Is performed. To the best of our knowledge, the fibers of the present invention exhibit the best photodarkening properties of any high concentration of Yb-doped silica fibers.

Alternative aspects

The above-described arrangement is only one example of many possible specific embodiments, and it is understood that the principles of the invention can be applied with this assumption. Those skilled in the art can make numerous and various other arrangements in accordance with the principles of the invention without departing from the principles and scope of the invention.

In particular, there are many ways to form SCA. It is desirable to rapidly cool the carrier gas stream saturated with precursor vapors, causing high saturation, and alternately generating precursors into homogeneous nucleates to form aerosol particles. Cooling may occur by conduction cooling, radial cooling mixing, or adiabatic expansion (SK Friedlander, Snore Dust and [laze, John Wiley & Sons, New York, NY, 1977, which is incorporated herein by reference]]. . However, chemical reactions can also be used to form aerosols. For example, as described above, RE chloride is reacted with oxygen at a temperature at which RE chloride is steam (eg, 950 ° C.). At these high temperatures the oxide can form a RE oxide aerosol. On the other hand, a precursor, for example aluminum (Al), may react with Cl ₂ to produce Al ₂ Cl ₆ vapor (eg at 350 ° C.), which may then be cooled to form an aerosol (see: The above description of the generator (12a) wherein the first chamber (12.2) is a reaction chamber.

It may also be advantageous to vaporize the aerosol particles before they flow into the performance tube 16.2. As shown in FIG. 3, the aerosol 12.0 flows into a tube 16.7 located concentrically inside the feed tube 16.1. Near its end, the inner tube (16.7) is heated with an external heating source (16.9). The aerosol 12.0 is vaporized and then flows into the base tube 16.2 as steam (FIG. 1). Oxygen flows into feed tube 16.1 to oxidize the aerosol and vapor that is delivered to the delivery system of FIG. 1. Alternatively, 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 so that the aerosol is not oxidized beforehand, ie before the aerosol is vaporized.)

If the aerosol particles are larger for high weight charges, or if the aerosol particles are agglomerated too much (in spite of filtration) due to the long delivery residence time and the fibers begin to signal undesirable rare earth clustering, the method is preferred. can do. When the heated tube 16.7 is not used, the particles are vaporized by being oxidized before they approach or vaporize the hot zone of the MCVD system forming the ideal (LVP vapor mixed with HVP vapor). If the particles are completely vaporized before they are oxidized, the size of the delivered particles is important in terms of transfer efficiency, but not in terms of the optical properties of the fibers. There are several indications of what happens with YbCl ₃ . However, the RE-chloride particles may first be oxidized with other RE dopants, in which case the size of the particles may affect the size of the oxide particles, so that their size is important and the size as small as possible needs to be.

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 aerosol generator 12a, 12a ′ and the deposition system 16. The oxidant can separate the oxidation chamber 20 as shown in FIG. 1 or simply the upper chamber 12.3 of the generator 12a (O ₂ flows into the tube 24 and He flows into the tube 22). May be). However, the oxide can have an extremely low vapor pressure, which means that the oxide particles are not vaporized in the high temperature region of the substrate tube, so that they can be less homogenized in the deposited glass layer. Nevertheless, those skilled in the art will appreciate that when the use of oxides improves the delivery of aerosol particles, for example, or when the use of oxides has only one method for forming aerosols of a particular dopant, It will be appreciated for this reason that it is advantageous to deliver the aerosol as an oxide.

Finally, certain aspects of the aerosol process of the present invention have been described and claimed as a method / apparatus for manufacturing an optical waveguide, and in the case of manufacturing optical fibers, firstly preparing a base material and subsequently drawing fibers therefrom. It is intended to contain detailed processes.

Multicomponent  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 precursor of a host material (eg chloride) and / or an oxide of the dopant or host material. For example, MCA includes particles in which each particle is a composite of two (or more than two) RE dopant precursors, such as YbCl ₃ and ErCl ₃ . Alternatively, the MCA includes particles in which each particle is a composite of a RE dopant precursor and a non-RE LVP dopant, for example YbCl ₃ and AlO ₃ (alumina). MCA, on the other hand, includes particles in which each particle is a composite of an oxide of an RE dopant precursor (eg YbCl ₃ ) and an HVP dopant (eg Ge ₂ O ₃ ) and / or an oxide of a host material (eg SiO ₂ ). .

The MCA aerosol can be produced, for example, using generator 12a of FIG. 2. Thus, the lower temperature secondary carrier gas of the generator 12a may contain suitable seed particles to initiate condensation of RE vapors. Alternatively, the seed particles may themselves be produced by another separate generator. In general, the seed particles may be LVP precursors or oxides such as RE chloride, or alumina, or the seed particles may be HVP oxides such as SiO ₂ or Ge ₂ O ₃ , or combinations thereof, ie, Component seed aerosol.

In the latter case, the seed particles are preferably a homogeneous blend of the respective aerosol components, which is advantageous in the production of homogeneous glass bodies, in particular optical fibers.

Thus, according to another aspect of the invention, the invention is 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 is produced. Generating (a) a first aerosol comprising first particles containing a first LVP precursor, comprising (a) and supersaturating the LVP vapor to form an aerosol; Separately generating steam of the other components; (C) convection circulating the aerosol of step (a) and the vapor of step (b) to a deposition system containing a substrate; And (d) forming on the surface of the substrate at least one doped layer comprising a dopant containing convection circulated aerosol and vapor in step (c). In this aspect of the invention, the aerosol can be MCA or SCA.

The method can be carried out using the apparatus described above in connection with FIGS.

The aerosol delivery system according to the present invention can easily handle LVP precursors such as RE precursors in a short time, and can be used in conjunction with various glass deposition systems such as MCVD, OVD and VAD, as well as fiber optic and planar waveguides. It can also be applied to the manufacture of a glass body comprising.

Claims (52)

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, (A) producing a first aerosol comprising first particles of a first LVP precursor, each first particle comprising only the first LVP precursor of the first dopant, Step (b) of separately generating steam of the other components (the step of producing (a) and (b) is carried out at a location remote from the deposition system used to form the glass body), (C) convection the aerosol of step (a) and the vapor of step (b) to a deposition system comprising a substrate from a location remote from the deposition system and And (d) forming at least one doped layer on the surface of the substrate, the at least one doped layer comprising the aerosol convection in step (c) and the dopant contained in the vapor. The method of claim 1, further comprising filtering the first aerosol to remove aerosol particles that fall outside a range of sizes and to permeate only aerosol particles belonging to the same size range, wherein the filtering step comprises aerosol generation step (a). A process for producing a glass body, characterized in that it is carried out by at least one component that does not contain any of the generators used in or the tubes used in the convection step (c). The method of claim 2, wherein the filtration step removes particles outside the size range of about 0.01 to 10 μm and permeates only aerosol particles belonging to the same range. The process of claim 1 wherein the producing step (a) comprises heating the LVP precursor at a first temperature above room temperature, and the convection step (c) convections the aerosol through a tube maintained at a temperature below the first temperature. Method for producing a glass body, characterized in that it comprises a step of. The method of claim 1 wherein the generating step (a) Providing an LVP precursor to a first chamber of the vessel (a1), Heating the LVP precursor to provide its vapor (a2), Flowing a carrier gas into the first chamber to produce a gas mixture containing the precursor in a second chamber of the vessel (a3), (A4) flowing a colder carrier gas into the second chamber to condense the vapor and form an aerosol of the precursor and Extracting the aerosol from the container (a5). The method of claim 5, wherein the carrier gas is saturated with the precursor. The method of claim 1, wherein the glass body is a planar waveguide. The method of claim 1, wherein the waveguide is made as a silica optical fiber. The method of claim 8, The deposition system comprises an MCVD system, the substrate comprises a substrate tube, the MCVD system comprises a feed tube axially coupled to the substrate tube and a concentric inner tube disposed inside the feed tube, Convection step (c) comprises convection the aerosol into one of the inner tube and the feed tube and heating the aerosol to vapor phase prior to entering the substrate tube, thereby producing a glass body. Way. The method of claim 1, Another component is a second dopant having a second LVP precursor, Further comprising a further step of separately producing a second aerosol comprising second particles of a second LVP precursor, each second particle of which comprises only a second LVP precursor of a second dopant, Method for producing a glass body. The method of claim 10, further comprising the step of maintaining the first aerosol and the second aerosol in parallel fluid delivery with respect to each other. The method of claim 10, further comprising mixing the aerosols of step (a) with each other before convection to the deposition system. The method of claim 1, further comprising mixing the aerosols of step (a) with the vapor of step (b) before convection to the deposition system. 9. The method of claim 8, further comprising the step of forming a base material comprising one or more doped layers and withdrawing the optical fiber from the base material. The method of claim 1, wherein the first LVP particles and the carrier gas do not contain any organic compounds. The method of claim 1, wherein the first LVP precursor is chloride. The method of claim 16, wherein the first particles are suspended in a carrier gas of He. 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 light aging of the optical fiber is reduced when the light rays develop along at least the Yb-doped region. The method of claim 1, wherein the first dopant is selected from the group consisting of Er, Yb, Nd, Tm, Ho and La. The method of claim 1, wherein the deposition system oxidizes and vaporizes the precursors delivered to the system, and vaporizes in the deposition system before most of the LVP precursors are oxidized. The method of claim 1, wherein most of the aerosol particles are oxidized before delivery to the deposition system. The method of claim 1, wherein the forming step (a) and the forming step (b) reach equilibrium before the base material forming convection step (c). The method of claim 1, further comprising the step of monitoring the size, number, or both of the first particles produced in step (a) and controlling the operating parameters of step (a) corresponding to the monitoring step. Characterized in that the glass body manufacturing method. The method of claim 1, wherein the glass body is made of glass soot. A method of making an optical fiber comprising a plurality of components and wherein at least one component is a first rare earth dopant having a first LVP precursor, Providing an LVP precursor to a first chamber of the vessel (a1), heating the LVP precursor to a temperature above room temperature to provide a vapor of a carrier gas containing the first precursor in the second chamber of the vessel (a2), Flowing a carrier gas into the first chamber to produce a gas mixture containing the precursor in a second chamber of the vessel (a3), wherein a lower temperature carrier gas is flowed into the second chamber to condense vapor and Forming aerosol (a4) and extracting the aerosol from the vessel (a5), wherein the first particles of the first LVP precursor comprise first particles of each of the first dopants Generating a first aerosol comprising (a), (B) generating steam of the silica precursor separately (the production step (a) and the production step (b) are performed at a location remote from the deposition system used to form the optical fiber), (C) convection the first aerosol and silica vapor from a location remote from the deposition system, through a tube maintained at room temperature or slightly higher, to the MCVD system comprising the substrate, (D) forming a layer of silica doped from the aerosol particles and vapor convection in step (c) on the inner wall of the substrate tube, and And (e) disintegrating the substrate tube to form a fiber base material. 27. The method of claim 26, further comprising filtering the first aerosol to remove aerosol particles that fall outside of a range of sizes and permeate only aerosol particles belonging to the same size range, wherein the filtering step comprises aerosol generation step (a). A method for producing an MCVD silica fiber, characterized in that it is carried out by at least one component which does not comprise the generator used in the convection or the tube used in the convection step (c). 27. The system of claim 26, wherein the MCVD system comprises a feed tube axially coupled to the substrate tube and a concentric inner tube disposed inside the feed tube, Convection step (c) comprises convection the aerosol into the inner tube and heating the aerosol to vapor phase before entering the substrate tube. 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 when light rays develop along the Yb-doped region, light aging of the optical fiber is reduced. 27. The method of claim 26, wherein the first LVP particles and the carrier gas do not contain any organic compounds. 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, Generating a first aerosol comprising first particles comprising a first LVP precursor, including providing a vapor of the LVP precursor (a1) and supersaturating the LVP vapor to form an aerosol (a2) a), (B) separately generating vapors of other components, (C) convection the aerosol of step (a) and the vapor of step (b) to a deposition system comprising a substrate and Forming (d) at least one doped layer from the aerosol and vapor contained dopant in step (c) on the surface of the substrate. 35. The glass body of claim 34, wherein step (a2) comprises flowing the primary carrier gas through the LVP vapor to accompany the LVP vapor and condensing the vapor accompanied to form an aerosol. Manufacturing method. 36. The method of claim 35, characterized in that the condensation step comprises a lower temperature secondary carrier gas through the vapor entrained. 35. The method of claim 34, wherein step (a1) causes a chemical reaction to flow the reactive gas onto the precursor of the LVP precursor to produce an LVP precursor vapor. 38. The method of claim 37, wherein the subprecursor comprises a metal body and 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) adiabaticly 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 do not contain any organic compounds. The method of claim 34, wherein in step (a2) the first LVP precursor is condensed on the seed aerosol. 43. The method of claim 42, wherein the seed aerosol comprises an LVP material. The method of claim 43, wherein the seed aerosol is selected from the group consisting of RE precursor aerosols and alumina aerosols. 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 dopants and host materials. 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 producing step (a) and producing step (b) are performed at a distance from the deposition system used to form the glass body, and convection step (c) is performed with the aerosol of producing step (a). Characterized in that 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 step of removing the aerosol particles that fall outside a certain range of sizes and filtering the first aerosol to permeate only aerosol particles belonging to the same size range, wherein the filtering step comprises aerosol generation step ( A process for producing a glass body, characterized in that it is carried out by one or more parts which do not contain the generator used in a) or the tube used in the convection step (c). The method of claim 46, wherein the filtration step removes particles outside the size range of about 0.01 to 10 μm and permeates only aerosol particles belonging to the same range. 35. The method of claim 34, further comprising the step of monitoring the size, number or both of the first particles produced in step (a) and controlling the operating parameters of step (a) in response to the monitoring step. Characterized in that the glass body manufacturing method. A container having a first chamber and a second chamber in fluid communication with each other (the first chamber is designed to contain LVP material), A heater designed to heat the LVP material embedded in the first chamber, A first inlet designed to flow a primary gas into the first chamber to produce a vapor compound in the second chamber comprising one or more elements of the LVP material, A second inlet designed to flow colder carrier gas into the second chamber and An aerosol generator comprising an outlet designed to extract an aerosol from a vessel.

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