CN102120685A - Method for manufacturing optical fiber prefabricated rod - Google Patents

Abstract

The invention relates to a method for manufacturing an optical fiber prefabricated rod, comprising the steps of: (1) growing a passivation layer on a fluorine-doped layer of a quartz base tube; (2) generating an evacuating nozzle; (3) sleeving and connecting the tube and a rod; (4) shrinking; and (5) grinding. The method provided by the invention has good process repeatability, and the manufactured optical fibers have favorable radiation resistance and have low loss in a near infrared band, an ultraviolet band and an invisible light band.

Description

The manufacture method of preform

Technical field

The present invention relates to a kind of making method of quartzy core fibre prefabricated rods, particularly a kind of making method of prefabricated bar of optical fiber with quartz core and fluorine adulterated clad.

Background technology

In people's lives and military field, extensively need high power laser, visible light, UV-light transmission medium and radioprotective optical fiber.For example, high-power ytterbium-doping optical fiber laser needs powerful pump light, and the luminous energy that single semiconductor laser can provide is limited, therefore, the laser that need send more semiconductor laser converges to together, and optical fiber with quartz core and fluorine adulterated clad just plays this light beam medium; Optical fiber with quartz core and fluorine adulterated clad can also be used to making the required multi-mode coupler of optical fiber laser.In addition, optical fiber with quartz core and fluorine adulterated clad medically is being used to medical diagnosis on disease and treatment because lower UV-light transmission loss is arranged; Because optical fiber with quartz core and fluorine adulterated clad also has good radiation-resisting performance, so be used as the data transmission line of naval vessel and aircraft.

At present, external making prefabricated bar of optical fiber with quartz core and fluorine adulterated clad is that using plasma external sediment technology (POD) is produced, carry out the growth of rock quartz core rod headed by its making method earlier, approach one deck fluoro-alloyed quartz glass in the plug outside deposition of thin that generates then, form the heavily doped fluorine cladded-fiber of quartzy core prefabricated component, under hot conditions, stretch again.POD method principle is simple, and its material source and reactant gases be all by plasma shower nozzle reacting by heating be ejected into the quartz pushrod surface, but its microwave takes place, control, transmission and to participate in chemical reaction be a quite complicated process.So it is that technology is simple, the equipment complexity.POD equipment complex and expensive, 1,000,000 Euros of POD apparatus values be the more important thing is the at present domestic this equipment that do not have.

The traditional technology of making the large core fiber prefabricated rods both at home and abroad has two kinds, promptly improved chemical vapor deposition method (MCVD technology) and plasma activated chemical vapour deposition technology (PCVD technology), and its basic step is identical substantially, and making processes is as follows:

Adopt photoconduction level silica tube as reaction tubes, in pipe, feed reactant gases and material source SiC14, POCl3, F12, O2, light heating source then, if use the MCVD glass work lathe, just light the oxyhydrogen flame heating source, if use the PCVD glass work lathe, just open the moving plasma heating source of microwave, purpose is identical, makes to generate SiO2, P2O5, SiF4 glass by material source and the gas generation chemical reaction that feeds, deposit to the internal surface of silica tube, form so-called optical fiber sealing coat, when treating that this settled layer grows into design thickness, carry out the growth of fiber core layer.

During the sandwich layer growth, feed reactant gases and material source SiC14, GeCl4, O2 in pipe, improve depositing temperature, the sandwich layer glass of growing layer by layer when thickness to be grown reaches design requirements, can stop.Further improve depositing temperature then, this silica tube is shrunk to rod, form fibre-optical preform.Like this, inject material source, carry saturated material source gas and enter crystal reaction tube, under hot conditions, carry out chemical reaction, generate different doped-glasses with the sealing coat zone, form fiber optical waveguide through wire drawing at core by oxygen.

The advantage that tradition MCVD technology and PCVD technology are made the large core fiber prefabricated rods is that equipment is relatively cheap, have only 30～400,000 Euros as the MCVD equipment price, but all there are many defectives: still be PCVD technology no matter with MCVD, because growth that will be in layer, so its process of growth all is very long, wastes time and energy; And the transformation efficiency of material source has only 40%, the material quilt waste in vain of considerable part has been arranged, the cost height; Owing to the coefficient of expansion difference between the covering of core district of mixing Ge and no Ge is very big, cause in prefabricated component making processes, very easily burst, yield rate reduces.

Summary of the invention

In order to solve above-mentioned drawback, the invention provides a kind of method of making preform, on fluorine-doped quartz substrate tube basis, make preform, it is characterized in that may further comprise the steps:

(1) mixes at the silica based bottom tube and carry out passivation layer growth on the fluorine layer: in mixing the fluorine pipe, feed reactant gases and material source, open heating source, under 1600 ℃～2400 ℃ temperature, mix the fluorine pipe to whole and carry out the passivation layer growth; Reactant gases is an oxygen, and material source is SiC14;

(2) mouth of finding time generates: process the mouth of finding time that is used to vacuumize on the fluorine-doped quartz substrate tube that passivation is good;

(3) manage excellent socket: will handle clean rock quartz core rod and put into the fluorine-doped quartz pipe of being with the mouth of finding time, one end of scorification substrate tube, make itself and quartz pushrod closely sintering manage internal pore then and clean together, clean finish after again with substrate tube and quartz pushrod sintering together at the other end; Heating whole should the quartz external member and vacuumize from the mouth of finding time, and treats to seal the mouth of finding time after vacuum tightness reaches requirement;

(4) shrink: the quartzy external member of handling through (3) step is fixed on the glass work lathe, in 1600～2400 ℃ temperature range, is shrunk to the fibre-optical preform of real core;

(5) grind: adopt grinding machinery, the outmost quartzy covering of above-mentioned fibre-optical preform is ground away, expose the fluorine-doped quartz covering.

Embodiment

In the present embodiment, will select for use MCVD technology (equipment) to make prefabricated bar of optical fiber with quartz core and fluorine adulterated clad, the fluorine-doped quartz substrate tube of employing is made by PCVD technology, and external diameter is that 28mm, wall thickness are 2mm, to mix the fluorine layer thickness be 1.5mm.Because the fluorine-doped quartz substrate tube is contaminated in processes such as carrying, it is not really clean to mix the fluorine laminar surface, so at first need to carry out polished finish:

At fluorine-doped quartz pipe two ends with in the oxyhydrogen flame welding near the quartzy supporting tube of fluorine-doped quartz bore, at ambient temperature, use pure hydrofluoric acid (HF) flushing fluorine-doped quartz pipe, after the time reached for 10～300 seconds, with the deionized water at normal temperature flushing, use 50～100 ℃ of deionized water rinsings more earlier; The SF6 and the flow that feed flow then and be 500ml/m in mixing the fluorine pipe are the O2 of 1000ml/m, light the hydrogen-oxygen torch, under 2000 ℃ of temperature, move back and forth along silica tube, and whole silica tube polished.Polishing gas and material source can also comprise helium and F12.

After polished finish is finished, mix at the silica based bottom tube and to carry out passivation layer growth on the fluorine layer: close and cut off SF6 material source and hydrogen-oxygen torch, GeCl4, the BBr3 of 5ml/m etc. of F12, the 5ml/m of the POCl3 of SiC14, the 25ml/m of feeding 400ml/m and 5ml/m in mixing the fluorine pipe, again open the hydrogen-oxygen torch and move along silica tube, under 2000 ℃ of temperature, mix the fluorine pipe to whole and carry out the passivation layer growth, passivation layer thickness is 3～120 μ m.

Passivation Treatment finishes, and by the method for mechanical workout, processes a mouth of finding time that is used to vacuumize on the silica based bottom tube.

Next manage excellent socket: with diameter is that the rock quartz core rod of 20mm is put into the good fluorine-doped quartz substrate tube of passivation, adopt an end of hydrogen-oxygen torch scorification silica based bottom tube, make the tight sintering of itself and rock quartz core rod together, and the central axis of rock quartz core rod and silica based bottom tube is coincided, the silica based bottom tube the other end is reserved as sour water and is handled mouth; After adopting hydrofluoric acid and high purity deionized water to clean the space that forms between rock quartz core rod and the silica based bottom tube, shut sour water with the hydrogen-oxygen torch and handle mouthful this end; Heat the whole aqueous vapor evaporation that should the quartz external member make wherein, and chew from finding time and to find time, vacuum tightness is 1 * 10-3～8 * 10-1 torr, treat that vacuum tightness meets the demands after, as 1 * 10-1 torr, shut the mouth of finding time with oxyhydrogen flame.

Manage and carry out shrink process after excellent socket finishes: this quartz external member is retightened on the MCVD glass work lathe, light the hydrogen-oxygen torch, 2200 ℃ of condition lower edge silica tube operations, silica based bottom tube 9 is shunk, sinter a real core fibre prefabricated component into rock quartz core rod 8.

At last, carry out the grinding of the quartzy part of fibre-optical preform substrate tube: the real core fibre prefabricated component of above-mentioned preparation is taken off, carry out the radial refractive index distribution measurement judging whether it meets the demands, and determine to mix the outward flange diameter of fluorine layer; With grinding machinery the quartzy part of the outmost substrate tube of this fibre-optical preform is ground away, expose and mix the fluorine covering, after hydrofluoric acid and deionized water processing, prepare wire drawing.

Can see that by the foregoing description the inventive method adopts common MCVD equipment, and is simple, cheap with POD equipment structure compared.On the other hand, the inventive method does not need grow layer by layer sandwich layer and sealing coat, and is therefore time saving and energy saving, also improved the transformation efficiency of material source simultaneously, reduced cost; Because the coefficient of thermal expansion differences of mixing between fluorine covering and the quartzy core is little, so with respect to traditional technology, dwindled the coefficient of thermal expansion differences between covering and the core district, makes that prefabricated component is difficult for bursting in making processes, has improved yield rate.In a word, the inventive method almost can solve all problems that is present in the traditional technology.

The foregoing description has selected for use MCVD technology (equipment) to make prefabricated bar of optical fiber with quartz core and fluorine adulterated clad, this just explanation for example.Obviously, according to the inventive method, can also select for use PCVD technology (equipment) to make prefabricated bar of optical fiber with quartz core and fluorine adulterated clad.Other aspects can suitably be adjusted according to inventive concept as reactant gases, material source, Heating temperature etc., and described embodiment should not be construed as limitation of the present invention.

Claims (1)

1. the manufacture method of a preform is made preform on fluorine-doped quartz substrate tube basis, it is characterized in that may further comprise the steps:

(1) mixes at the silica based bottom tube and carry out passivation layer growth on the fluorine layer: in mixing the fluorine pipe, feed reactant gases and material source, open heating source, under 1600 ℃～2400 ℃ temperature, mix the fluorine pipe to whole and carry out the passivation layer growth; Reactant gases is an oxygen, and material source is SiCl4;

(2) mouth of finding time generates: process the mouth of finding time that is used to vacuumize on the fluorine-doped quartz substrate tube that passivation is good;

(3) manage excellent socket: will handle clean rock quartz core rod and put into the fluorine-doped quartz pipe of being with the mouth of finding time, one end of scorification substrate tube, make itself and quartz pushrod closely sintering manage internal pore then and clean together, clean finish after again with substrate tube and quartz pushrod sintering together at the other end; Heating whole should the quartz external member and vacuumize from the mouth of finding time, and treats to seal the mouth of finding time after vacuum tightness reaches requirement;

(4) shrink: the quartzy external member of handling through (3) step is fixed on the glass work lathe, in 1600～2400 ℃ temperature range, is shrunk to the fibre-optical preform of real core;

(5) grind: adopt grinding machinery, the outmost quartzy covering of above-mentioned fibre-optical preform is ground away, expose the fluorine-doped quartz covering.