CN102086089A - Method for manufacturing rare-earth-doped fiber precast rod - Google Patents

Abstract

The invention discloses a method for manufacturing a rare-earth-doped fiber precast rod. The method comprises the following steps of: depositing a loose cigarette ash core layer on the inner surface of a quartz deposition pipe at a deposition temperature; then, soaking the loose cigarette ash core layer in a rare-earth-contained solution so that rare-earth elements in the solution are absorbed in holes of the loose cigarette ash core layer; then, arranging the deposition pipe in a sintering furnace and drying the loose cigarette ash core layer with inert gases; sintering the loose cigarette ash core layer at a low temperature into a glass layer; and finally, melting and concentrating the deposition pipe into a solid precast rod. The invention can effectively control the volatilization of P2O5, GeO2 and rare-earth elements of the loose cigarette ash core layer in the drying and sintering processes so that the high-concentration rare-earth elements can be doped in the precast rod core layer and can be more uniformly distributed on the precast rod core layer in the radial direction. Optical fiber drawn by the rare-earth-doped fiber precast rod which is manufactured in the invention can be used for manufacturing fiber amplifiers, fiber lasers and fiber sensors.

Description

A kind of method of making the rare earth doped fiber prefabricated rods

Technical field

The present invention relates to the manufacture method of preform, particularly relate to manufacture method as the preform of a kind of sandwich layer doped with rare-earth elements of fiber amplifier, optical fiber laser and Fibre Optical Sensor.

Background technology

The rare-earth doped optical fibre that doped with rare-earth elements obtains in the silica fibre can be used for making fiber amplifier, optical fiber laser and Fibre Optical Sensor.With the erbium-doped fiber is erbium-doped fiber amplifier (the erbium doped fiber amplifier of gain media, EDFA), not only solved the restriction of decay to optical-fiber network transfer rate and distance, and started the wavelength-division multiplex technique of 1.55 mu m wavebands, thereby ultra-high speed, vast capacity, over distance wavelength-division multiplex, dense wave division multipurpose, full light transmission, soliton transmission etc. will be become a reality.And with the Yb dosed optical fiber be gain media optical fiber laser especially with its good beam quality, compact construction, be easy to plurality of advantages such as integrated, be widely used in fields such as industry, medical treatment, military affairs, and be expected to replace most of traditional superpower laser.In addition, rare-earth doped optical fibre can also be used to make Fibre Optical Sensor.

Optical fiber is drawn by prefabricated rods and forms.Gas phase deposition technology is generally adopted in the manufacturing of preform at present, comprise axial vapor deposition method (vapor axial deposition, VAD), outside vapour deposition process (outside vapor deposition, OVD), modified chemical vapor deposition process (MCVD) (modified chemical vapor deposition, MCVD) and plasma chemical vapor deposition (plasma chemical vapor deposition, PCVD).Make the required raw material of prefabricated rods at normal temperatures normally gas (as O₂, Cl₂Deng) or liquid with higher vapor pressure (as SiCl₄, GeCl₄Deng).And when making the required rare earth dopant (being generally rare earth halide) of rare-earth doped optical fibre and only being heated to 500～1000 ℃, could guarantee enough vapour pressures, make its can with other popular response thing gas participation vapor deposition reaction.Therefore adopt conventional prefabricated rods manufacturing technology to be difficult to realize rear-earth-doped.The method that is used to make the rare-earth doped optical fibre prefabricated rods in the prior art comprise gas phase doping method, solute doping method, the direct sedimentation of nanoparticle (Direct Nanoparticle Deposition, DND), sol-gel method and solution atomization method.Wherein most widely used is the solute doping method.J. E. Townsend etc. is at " Solution-doping technique for fabrication of rare-earth-doped fibers ", Electronic letters, 1987,23 (7), the 329-331 page or leaf has been described and has been adopted the MCVD binding soln to soak the method for making rear-earth-doped prefabricated rods: (a) contain SiO with ordinary method formation of deposits in quartzy deposited tube 12₂-P₂O₅The optical fiberinner cladding 13 of-F, wherein P₂O₅Can reduce glass viscosity, make molten contracting be more prone to P₂O₅Doping improved quartzy specific refractory power, mix F and can reduce specific refractory power, thereby make the specific refractory power of inner cladding and the refractive index match of quartzy deposited tube.Oxyhydrogen flame blowtorch 11 is used for heating deposition pipe 12.(b) reduce the loose cigaretteash sandwich layer 14 of temperature deposition, shown in Figure 1A of the present invention.(c) take off depositedtube 12, in thesolution 10 that contains rare earth element, soaked about one hour, shown in Figure 1B of the present invention.(d) after soaking well, clean loose cigaretteash sandwich layer 14 with acetone, and reinstall on the lathe.(e) be warming up to 600 ℃ and feed Cl simultaneously₂Dehydrate.(f) the loose cigaretteash sandwich layer 14 of sintering is a transparent glass layer, shown in Fig. 1 C of the present invention.(g) shorten solid prefabricated rods into the depositedtube 12 that dehydrates is at high temperature molten.Fig. 2 A of the present invention and Fig. 2 B show before depositedtube 12 and loose cigaretteash sandwich layer 14 molten the contracting respectively and the cross sectional representation after molten the contracting.

The cluster phenomenon takes place in rare earth element easily in quartz substrate, limited the doping content of rare earth element.Mix Al in the silica fibre sandwich layer₂O₃The cluster effect that can effectively suppress rare earth element improves the solubleness of rare earth element in quartz.While Al₂O₃Can reduce the volatilization of rare earth element.Yet Al₂O₃Doping content in quartz is subjected to the restriction of himself solubleness, works as Al₂O₃Concentration when surpassing 4mol%, will cause phase-splitting and crystallization.Know, mix P in the quartz₂O₅Can stop Al₂O₃Crystallization.P₂O₅To mix be at SiCl during by loose cigarette ash sandwich layer deposition₄Add POCl in the air-flow₃Gas is realized.High density P₂O₅Mix and not only can guarantee high-concentration dopant Al₂O₃Can not produce phase-splitting and crystallization, but also improve the doping content of rare earth element, and can improve the performance of rare earth element.

On the other hand, doped with Ge O in the fiber core layer₂, behind ultraviolet radiation, can cause the variation of defective in the optical fiber, thereby cause change of refractive.Utilize this principle, germnium doped fiber can form fiber grating through periodically producing index modulation.The photosensitivity of germnium doped fiber depends on the concentration of germanium in the optical fiber, and the concentration of germanium is high more, at high temperature decomposites more GeO, and the photosensitivity of optical fiber is just strong more.

Prior art adopts MCVD binding soln doping method manufacturing sandwich layer to contain P₂O₅Perhaps GeO₂The rare earth doped fiber prefabricated rods, can produce following problem: after (1) solution soaking is finished, deposited tube is reinstalled on the MCVD lathe P of loose cigarette ash sandwich layer internal surface in dry, the agglomerating process₂O₅Perhaps GeO₂Can produce volatilization, thereby cause the component of prefabricated rods sandwich layer to change, influence the final use properties of optical fiber.(2) P₂O₅And GeO₂The doping quartz can improve specific refractory power, POCl when depositing by controlling loose cigarette ash sandwich layer₃, GeCl₄With SiCl₄Gas flow ratio can control the parameter of optical fiber such as numerical value aperture (numerical aperture, NA), and P₂O₅, GeO₂Volatilization cause the control of optical fiber parameter become the difficulty.(3) field intensity of transmission light is approximated to Gaussian distribution in the optical fiber, and light intensity is in axis place maximum, and successively decreases to the periphery.Therefore the radial distribution of rare earth element in fiber core layer needs strict control, thereby makes its efficient reach maximization.Yet in drying, the sintering process, rare earth element can be along with P₂O₅Perhaps GeO₂Volatilization and run off, the distribution that finally causes rare earth element radially to be gone up at the preform sandwich layer is the central concave shape.

Summary of the invention

The technical assignment of the technical problem to be solved in the present invention and proposition is to overcome prior art to adopt MCVD binding soln doping method manufacturing sandwich layer to contain P₂O₅Perhaps GeO₂The existing loose cigarette ash sandwich layer that contains rare earth element of rare earth doped fiber prefabricated rods P in dry, sintering process₂O₅, GeO₂The volatilization problem, and by P₂O₅, GeO₂Volatilization and the optical fiber parameter that causes changes and rare earth element in distribution center's depression problem that the preform sandwich layer is radially gone up, a kind of method of making the rare earth doped fiber prefabricated rods is provided.

Purpose of the present invention is achieved through the following technical solutions: a kind of method of making the rare earth doped fiber prefabricated rods is characterized in that may further comprise the steps:

The loose cigarette ash sandwich layer of internal surface deposition at quartzy deposited tube;

In containing the solution of rare earth element, soak described loose cigarette ash sandwich layer, the rare earth element in the solution is adsorbed in the hole of loose cigarette ash sandwich layer;

In sintering oven, use rare gas element and the described loose cigarette ash sandwich layer of dry chlorine;

The described loose cigarette ash sandwich layer of sintering is a glass coating;

Molten described quartzy deposited tube and the glass coating of contracting is solid preform.

As the optimization technique means, adopt the MCVD method to deposit described loose cigarette ash sandwich layer.

As the optimization technique means, described deposition is that the mixed gas with oxygen, silicon tetrachloride and impurity gas feeds and makes mixed gas generation chemical reaction form soot deposits by heating (as by the heating of oxyhydrogen flame blowtorch, also can be that other heating unit such as resistance furnace heat) in the described quartzy deposited tube to form described loose cigarette ash sandwich layer to the deposited tube internal surface; Described impurity gas is germanium tetrachloride or phosphorus oxychloride or the combination of the two.When implementing described sintering with the mixed gas of described impurity gas and oxygen, helium by described loose cigarette ash sandwich layer.

As the optimization technique means, described sedimentary temperature is 1200-1700 ℃.

As the optimization technique means, contain muriate or nitrate and a kind of co-dopant of at least a rare earth element in the described solution, described rare earth element ordination number is 57-71, described co-dopant is aluminum chloride or aluminum nitrate.

As the optimization technique means, described sintering carries out in sintering oven.

As the optimization technique means, described exsiccant temperature is 600-1300 ℃, and be 0.5-2 hour time of drying.

As the optimization technique means, described rare gas element when dry is a nitrogen.

As the optimization technique means, described agglomerating temperature is 1500-1600 ℃.

As the optimization technique means, the solvent of described solution is water or ethanol.

As the optimization technique means, the time that described loose cigarette ash sandwich layer soaks in solution is preferably 1 hour for being at least 0.5 hour.

The invention has the beneficial effects as follows: the sintering method of prior art is because torch flame temperature height causes P in the loose cigarette ash sandwich layer₂O₅, GeO₂Volatilization.Heating region generally only is about 2cm simultaneously, and the fluctuation of torch flame temperature and the fluctuation in the axial direction of deposited tube wall thickness all can cause the inhomogeneous of loose cigarette ash sandwich layer Heating temperature, thereby causes the axial ununiformity of prefabricated rods sandwich layer component and specific refractory power.By adopting the loose cigarette ash sandwich layer of sintering oven low-temperature sintering, make heat can be distributed in loose cigarette ash sandwich layer inside more equably, reduced the fluctuation of prefabricated rods sandwich layer component.The method according to this invention can effectively be controlled loose cigarette ash sandwich layer P in drying, sintering process₂O₅, GeO₂Volatilization, thereby the control of optical fiber parameter such as NA is more prone to, the further rare earth element that the prefabricated rods sandwich layer can doped with high concentration, the distribution that rare earth element is radially gone up at the prefabricated rods sandwich layer is more even.

Description of drawings

Figure 1A is the synoptic diagram of the loose cigarette ash sandwich layer of existing method deposition.

Figure 1B is existing method is soaked loose cigarette ash sandwich layer in solution a synoptic diagram.

Fig. 1 C is that the loose cigarette ash sandwich layer of existing method sintering is the synoptic diagram of transparent glass layer.

Fig. 2 A is the cross sectional representation of molten contract preceding deposited tube and loose cigarette ash sandwich layer.

Fig. 2 B is for melting the cross sectional representation of the deposited tube after contracting and the cigarette ash sandwich layer that loosens.

Fig. 3 A is the synoptic diagram of the loose cigarette ash sandwich layer of the inventive method deposition.

Fig. 3 B is the inventive method is soaked loose cigarette ash sandwich layer in solution a synoptic diagram.

Fig. 3 C is that the inventive method is dry in sintering oven, the synoptic diagram of the loose cigarette ash sandwich layer of sintering.

Number in the figure explanation: 11-blowtorch, 12-deposited tube, 13-inner cladding, the 14-cigarette ash sandwich layer that loosens, the 15-furnace core tube, the 16-heating member, 17-draws bar, 18-air feed port, 19-venting port.

Embodiment

The present invention will be further described below in conjunction with Figure of description.

The method of manufacturing rare earth doped fiber prefabricated rods of the present invention may further comprise the steps:

At first quartzy depositedtube 12 is polished (as the thermal-flame polishing), in order to eliminate cut impurity, surface irregularity and the collapsed cell on depositedtube 12 surfaces.

Then contain SiO in depositedtube 12 internal surfaces deposition₂-P₂O₅Theinner cladding 13 of-F, deposition method can be used existing method.P wherein₂O₅Can reduce glass viscosity, make molten contracting be more prone to P₂O₅Doping improved quartzy specific refractory power, mix F and can reduce specific refractory power, thereby make the specific refractory power ofinner cladding 13 and the refractive index match of quartzy deposited tube 12.In the deposition process, the accurate control that feeds the flow of depositedtube 12 unstripped gases can (deposit used raw material SiCl by entering foamed pot₄, GeCl₄Be liquid under the normal temperature, SiCl₄57.65 ℃ of boiling points, GeCl₄Therefore 84 ℃ of boiling points need carrier gas such as oxygen to take it out of feeding deposited tube by foamed pot; MCVD all adopts these means) carrier gas flux or directly the pilot-gas flow realize.Depositedtube 12 and flow throughoxyhydrogen flame blowtorch 11 heating of gas by depositedtube 12 outsides in the pipe, for depositedtube 12 and interior gas thermally equivalent thereof, deposited tube should rotate along its axis in deposition process, and the tube wall of deposited tube and the distance of blowtorch just can be consistent, thereby are heated evenly.The temperature of depositedtube 12 is measured by infrared thermometer.Temperature controlling is based on computer and MFC(mass flowmeter) to the adjusting of gas flow.When reactant gases enters the hot-zone that produces because ofoxyhydrogen flame blowtorch 11 heating deposition pipes through the process that the end (inlet end) of depositedtube 12 enters bydeposited tube 12, reach the needed temperature of reaction and will form glass particle.These glass particles flow with the other end (exit end) of heated air to depositedtube 12, when reaching the cold zone of depositedtube 12, because the thermograde that the footpath makes progress, thereby cause that glass particle deposits to the tube wall thermophoresis.Not sedimentary glass particle then flows in the loose body particle collector with waste gas.Blowtorch 11 moves (being that the direction that moves ofoxyhydrogen flame blowtorch 11 is identical with flowing to of reactant gases) from the inlet end of depositedtube 12 to exit end in deposition process, whenblowtorch 11 arrives depositedtubes 12 terminal, will rapid return to the gas inlet end of deposited tube 12.Along with moving ofblowtorch 12, sinter particle into very thin glass coating from the heat of blowtorch 11.Thereby depositing temperature should enough highly make the deposited particles vitrifying saturating, exceeds but should keep not making depositedtube 12 to deform.Blowtorch 11 periodically moves around, and formation in layer contains theinner cladding 13 of specific components in depositedtube 12, andinner cladding 13 effect is to prevent that impurity in the depositedtube 12 is (as OH^-) be diffused into sedimentary subsequently loose cigaretteash sandwich layer 14.

Reduce temperature subsequently, as the loose cigaretteash sandwich layer 14 of Fig. 3 A deposition.Depositing temperature should be not too high, sinters glass coating into to avoid loose cigaretteash sandwich layer 14, causessandwich layer 14 porositys low excessively, can't adsorb the enough solution that contains rare earth element 10.Depositing temperature should be not low excessively yet simultaneously, has enough intensity to guarantee loose cigaretteash sandwich layer 14, prevents that loose cigaretteash sandwich layer 14 comes off in the solution soaking process.Therefore, depositing temperature is a key parameter of making the rare earth doped fiber prefabricated rods, and depositing temperature scope of the present invention is 1200-1700 ℃ (when specifically implementing, this temperature is corresponding with the component of loose cigarette ash sandwich layer, different component depositing temperature differences).For doping content that improves rare earth element or the photosensitivity that increases optical fiber, need in loose cigarette ash sandwich layer, mix POCl₃Gas or GeCl₄Gas forms P₂O₅Or GeO₂Mix.P₂O₅Or GeO₂SiCl when adulterated concentration deposits by the loose cigaretteash sandwich layer 14 of MFC control₄Gas flow and POCl₃Gas flow or GeCl₄The ratio of gas flow realizes.Preparation high-concentration dopant P₂O₅Loose cigaretteash sandwich layer 14 time, needing to adopt oppositely, deposition prevent the excessive sintering of deposition process to loose cigarette ash sandwich layer 14.Oppositely deposition is that the direction that moves ofoxyhydrogen flame blowtorch 11 is opposite with the flow direction of reactant gases.

The depositedtube 12 that will contain loose cigaretteash sandwich layer 14 then is immersed in (referring to Fig. 3 B) in thesolution 10 that contains rare earth element.Contain muriate or nitrate and a kind of co-dopant of at least a rare earth element in the solution, the rare earth element ordination number is 57-71, and co-dopant is aluminum chloride or aluminum nitrate.Wherein the solvent of solution is water or ethanol.The concentration of rare earth chloride or nitrate is 0.001-0.1 mol/L, and the concentration of aluminum chloride or aluminum nitrate is 0-1.25 mol/L.The time of soaking is answered sufficiently long, so that contain in the hole that the solution of rare earth element can fully enter loose cigarette ash sandwich layer 14.Soak time was at least 0.5 hour, was preferably 1 hour.

After immersion is finished, discharge rest solution.Shown in Fig. 3 C depositedtube 12 is installed on the anchor clamps that drawbar 17,bar 17 is drawn in slow decline enters in the sintering oven deposited tube 12.Sintering oven is by heating member 16(resistance furnace or other heating unit) heatingfurnace core tube 15, heating zone length 400mm(± 25 ℃), depositedtube 12 is positioned at heating zone central authorities.Gas enters sintering oven fromair feed port 18, flows through loose cigaretteash sandwich layer 14 from the deposited tube lower port, flows out from sinteringoven venting port 19 through depositedtube 12 upperport.Drawing bar 17 speed of rotation is 3-10rpm.At first feed inert nitrogen gas and purge, elevated temperature is to 600-1300 ℃ then, and aerating oxygen, chlorine and helium dehydrate, to remove the OH in the loose cigarette ash sandwich layer^-Its reaction equation is:

2Cl₂?+?2H₂O?=?O₂?+?4HCl

2Si-OH?+?2Cl₂?=?2Si-Cl?+?O₂?+?2HCl

The main effect of He is auxiliary dehydration, atomic volume is little, diffusivity is high, the characteristics of stable performance because He has, penetrate into inside and can the performance of prefabricated rods not exerted an influence so it is easy to hole by loose cigaretteash sandwich layer 14, helium is brought Cl on the one hand into₂, O₂, make it fully to contact with loose cigaretteash sandwich layer 14, on the other hand, the waste gas and the moisture of dehydration reaction is brought out; O₂Effect be in order to prevent doped element (for example Ge, P) and Cl₂Halogenating reaction taking place volatilize away, causes Ge, P to run off.Be 0.5-2 hour time of drying.In the exsiccant process, rare earth chloride generally is converted into oxide compound under lower temperature.Adopt alap oxidizing temperature can reduce the volatilization of rare earth element.

After the drying and dehydrating, feed He, O₂Carry out sintering, the agglomerating temperature range is 1500-1600 ℃.The mixed gas of the contained impurity gas of oxygen, helium and deposition sandwich layer is by described loose cigaretteash sandwich layer 14 in the sintering step.Because 14 P that mixed in loose cigarette ash sandwich layer₂O₅, then when sintering, feed POCl₃Flow throughsandwich layer 14 and generate P with oxygen reaction₂O₅The volatilization of compensation P.

After sintering is finished, depositedtube 12 is promoted to the cooling of sintering oven outside, the cross section that attaches the deposited tube thatinner cladding 13, loose cigaretteash sandwich layer 14 are arranged this moment is shown in Fig. 2 A.At last depositedtube 12 is reinstalled on the MCVD lathe, (2200-2300 ℃) melts the transparent solid glass rods that shorten into shown in Fig. 2 B withinner cladding 13, loose cigaretteash sandwich layer 14 with depositedtube 12 under the high temperature.

Embodiment 1

Quartzy depositedtube 12 carries out high temperature (1800-2100 ℃) flame polish, eliminates cut impurity, surface irregularity and the collapsed cell on depositedtube 12 surfaces.Contain SiO for 10 layers in depositedtube 12 internal surfaces deposition under 1870 ℃ (general in 1800-2000 ℃ temperature range all can)₂-P₂O₅To beblowtorch 11 move 10 times and carry outdeposition 10 times to exit end from the inlet end of depositedtube 12 for 10 layers of described depositions of the inner cladding 13(of-F, actual formed 10 layers ofinner cladding 13 boundlessness on the transverse section, show as successive one deck, the deposition that following examples are addressed is same notion for 10 layers).Reduce depositing temperature to 1280 ℃, feed SiCl₄And GeCl₄The gas aggradation cigaretteash sandwich layer 14 that loosens.The depositedtube 12 that will contain loose cigaretteash sandwich layer 14 is immersed in the ErCl that contains 0.01 mol/L₃6H₂O, the YbCl of 0.05 mol/L₃6H₂The AlCl of O and 0.3 mol/L₃6H₂In theaqueous solution 10 of O about 1 hour.Subsequently, discharge excessive solution, depositedtube 12 is put into sintering oven, feed nitrogen and blow 30min, then progressively elevated temperature to 600-1300 ℃ of (the dry needs between a heating zone, in this temperature range all are drying processs), aerating oxygen, chlorine and helium dehydrate, and be 1.5 hours time of drying.After the drying and dehydrating, feed He, O₂Loose cigaretteash sandwich layer 14 is carried out sintering, and the agglomerating temperature is 1500 ℃.Feed GeCl in the sintering process₄Gas stream is crossed loose cigarette ash sandwich layer 14.At last depositedtube 12 is reinstalled on the MCVD lathe, shorten transparent solid glass rod into depositedtube 12 is molten under 2200 ℃ (in temperature ranges of 2000-2300 ℃ all can).(electron probe microanalysis, EPMA) test obtains GeO to present embodiment preform sandwich layer through electronic probe₂Concentration is 10wt%, Yb₂O₃Concentration be 1 wt%, Er₂O₃Concentration be 0.2 wt%, be drawn into optical fiber after, its numerical aperture is 0.12, naked fine diameter is 125 μ m, core diameter is 10 μ m, can be used for making Erbium-Doped Fiber Amplifier.

Embodiment 2

Quartzy depositedtube 12 carries out the thermal-flame polishing, eliminates cut impurity, surface irregularity and the collapsed cell on depositedtube 12 surfaces.Contain SiO for 10 layers in depositedtube 12 internal surfaces deposition under 1870 ℃₂-P₂O₅Theinner cladding 13 of-F.1550 ℃ are adopted oppositely deposition down, feed SiCl₄And POCl₃The gas aggradation cigaretteash sandwich layer 14 that loosens.The depositedtube 12 that will contain loose cigaretteash sandwich layer 14 is immersed in the YbCl that contains 0.07 mol/L₃6H₂The AlCl of O and 0.5 mol/L₃6H₂In theaqueous solution 10 of O about 1.5 hours.Subsequently, discharge excessive solution, depositedtube 12 is put into sintering oven, feed nitrogen and blow 30min, progressively elevated temperature is to 600-1300 ℃ then, and aerating oxygen, chlorine and helium dehydrate, and be 2 hours time of drying.After the drying and dehydrating, feed He, O₂Loose cigaretteash sandwich layer 14 is carried out sintering, and the agglomerating temperature is 1550 ℃.Feed POCl in the sintering process₃Gas stream is crossed loose cigarette ash sandwich layer 14.At last depositedtube 12 is reinstalled on the MCVD lathe, shorten transparent solid glass rod into depositedtube 12 is molten under 2200 ℃.Present embodiment preform sandwich layer obtains P through electron probe test₂O₅Concentration is 15wt%, Yb₂O₃Concentration be 3 wt%, be drawn into optical fiber after, its numerical aperture is 0.15, naked fine diameter is 125 μ m, core diameter is 11 μ m, can be used for making ytterbium-doping optical fiber laser.

Embodiment 3

Quartzy depositedtube 12 carries out the thermal-flame polishing, eliminates cut impurity, surface irregularity and the collapsed cell on depositedtube 12 surfaces.Contain SiO for 10 layers in depositedtube 12 internal surfaces deposition under 1870 ℃₂-P₂O₅Theinner cladding 13 of-F.Reduce depositing temperature to 1250 ℃, feed SiCl₄, GeCl₄And POCl₃The gas aggradation cigaretteash sandwich layer 14 that loosens.The depositedtube 12 that will contain loose cigaretteash sandwich layer 14 is immersed in the TmCl that contains 0.03 mol/L₃6H₂The Al(NO of O and 0.3 mol/L₃)₃9H₂In theethanolic soln 10 of O about 1 hour.Subsequently, discharge excessive solution, depositedtube 12 is put into sintering oven, feed nitrogen and blow 30min, progressively elevated temperature is to 600-1300 ℃ then, and aerating oxygen, chlorine and helium dehydrate, and be 1 hour time of drying.After the drying and dehydrating, feed He, O₂Loose cigaretteash sandwich layer 14 is carried out sintering, and the agglomerating temperature is 1600 ℃.Feed GeCl in the sintering process₄And POCl₃Gas stream is crossed loose cigarette ash sandwich layer 14.At last depositedtube 12 is reinstalled on the MCVD lathe, shorten transparent solid glass rod into depositedtube 12 is molten under 2200 ℃.Present embodiment preform sandwich layer obtains GeO through electron probe test₂Concentration is 8wt%, P₂O₅Concentration is 5wt%, Tm₂O₃Concentration be 0.3 wt%, be drawn into optical fiber after, its numerical aperture is 0.16, naked fine diameter is 125 μ m, core diameter is 8 μ m, can be used for making S-band thulium doped fiber amplifier and 2 mum wavelength optical fiber lasers.

The inventive method is not limited to the doping of rare earth element, can also be used for transition metal such as nickel, cobalt, chromium, the doping of metallic element bismuth and semiconductor-quantum-point.

Need to prove, the mode of the foregoing description only limits to describe embodiment, but the present invention is not confined to aforesaid way, and those skilled in the art can modify in not departing from the scope of the present invention in view of the above easily, and therefore scope of the present invention should comprise the disclosed principle and the maximum range of new feature.

Claims (10)

1. method of making the rare earth doped fiber prefabricated rods is characterized in that may further comprise the steps:

The loose cigarette ash sandwich layer of internal surface deposition at quartzy deposited tube;

In containing the solution of rare earth element, soak described loose cigarette ash sandwich layer;

In sintering oven, use rare gas element and the described loose cigarette ash sandwich layer of dry chlorine;

The described loose cigarette ash sandwich layer of sintering is a glass coating;

Molten described quartzy deposited tube and the glass coating of contracting is solid preform.

2. a kind of method of making the rare earth doped fiber prefabricated rods according to claim 1 is characterized in that: adopt the MCVD method to deposit described loose cigarette ash sandwich layer.

3. a kind of method of making the rare earth doped fiber prefabricated rods according to claim 1 is characterized in that: described deposition is that the mixed gas with oxygen, silicon tetrachloride and impurity gas feeds and makes mixed gas generation chemical reaction form soot deposits by heating in the described quartzy deposited tube to form described loose cigarette ash sandwich layer to the deposited tube internal surface; Described impurity gas is germanium tetrachloride or phosphorus oxychloride or the combination of the two.

4. a kind of method of making the rare earth doped fiber prefabricated rods according to claim 3 is characterized in that: when implementing described sintering with the mixed gas of described impurity gas and oxygen, helium by described loose cigarette ash sandwich layer.

5. a kind of method of making the rare earth doped fiber prefabricated rods according to claim 1 is characterized in that: described sedimentary temperature is 1200-1700 ℃.

6. a kind of method of making the rare earth doped fiber prefabricated rods according to claim 1, it is characterized in that: the muriate or nitrate and a kind of co-dopant that contain at least a rare earth element in the described solution, described rare earth element ordination number is 57-71, and described co-dopant is aluminum chloride or aluminum nitrate.

7. a kind of method of making the rare earth doped fiber prefabricated rods according to claim 1, it is characterized in that: described sintering carries out in sintering oven.

8. a kind of method of making the rare earth doped fiber prefabricated rods according to claim 1 is characterized in that: described exsiccant temperature is 600-1300 ℃, and be 0.5-2 hour time of drying.

9. a kind of method of making the rare earth doped fiber prefabricated rods according to claim 1 is characterized in that: described rare gas element when dry is a nitrogen.

10. a kind of method of making the rare earth doped fiber prefabricated rods according to claim 1 is characterized in that: described agglomerating temperature is 1500-1600 ℃.

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