Single-mode optical fiber (options), and the manufacturing method (variants)

 

The invention relates to fiber optics and can be used in the manufacture of single-mode optical fibers for transmission based on division multiplexing wavelengths. Fiber is generated by the deposition of SiO2from the gas phase on the outer surface of the glass rod containing the core and the first portion of the shell, to form a second part of the casing, sintering and extrusion to obtain fiber. In the first embodiment the ratio of the diameter of the first portion of the shell to the core diameter is in the range from 4.0 to 4.8, and the concentration of HE in the core, the first and second parts of the shell not higher than 0.1 million shares. In the second variant the ratio of the diameter of the first portion of the shell to the core diameter is more than 4.8, and the concentration of HE in the core and the first part of the shell not higher than 0.1 million shares, while the second part of the shell does not exceed 100 ppm. Reduced losses in the fiber in the range of 1380 nm and increased resistance to hydrogen. 4 N. and 8 C.p. f-crystals, 4 Il.

The technical FIELD,

The present invention relates to a method of manufacturing a single-mode optical fiber for optical communication. In cha is Bladet low loss at the wavelength of 1380 nm and excellent resistance to hydrogen.

The LEVEL of TECHNOLOGY

Recently there have been significant technology improvements in the field of transmission systems based on division multiplexing wavelength (or, in other words, using wavelength division multiplexing), with an increasing flow of information exchange. To increase throughput, it is important to ensure the expansion of the available spectral range. Currently, as the spectral range in which can be amplified signal via an optical fiber doped with erbium, use C-band (transmission) or L-band. As a form of implementation over a wide spectral range are currently engaged in the development of optical fiber doped with thulium, in which amplification can be performed in the range S-band, and Raman amplifier based on Raman scattering, in which amplification can be performed at any wavelength. In result, it becomes possible to carry out the amplification in all ranges, corresponding to areas of low loss optical fibers, hence the need of obtaining an optical fiber with a region of low losses in all the 0 nm and a large peak or maximum loss at the wavelength of 1380 nm, due to the presence of hydroxyl ion (OH). The presence of such a peak losses caused by the material from which is formed the optical fiber. Optical fiber made of quartz glass (i.e. glass-based silicon dioxide) having a mesh structure in which the molecules of SiO2interconnected randomly in three-dimensional patterns. If the net structure of impurities or defects is the emergence of new and breaking of old ties, therefore, these factors lead to the absorption of optical radiation. By evaluation calculation of this absorption of optical radiation, it was found that loss at the wavelength of 1380 nm can be caused by the hydroxyl ion (OH) existing in the quartz glass. Therefore, the greater the number contained in the hydroxyl ions (Oh), the greater the amount of losses that occur at the wavelength of 1380 nm.

As the peak loss is wide, the spectral ranges on either side of the peak of the loss cannot be used for optical communication. From a practical point of view there is a potential for optical communication in a wide spectral range in the case, if in the spectral range of 1380 nm can be perceived by the losses in the spectral range of 1380 nm, caused by IT, can be lowered by adjusting the values of the relationship of the diameter of the shell to the core diameter (relationship D/d) within a certain interval of values.

There is a possibility of manufacturing optical fiber with losses less than 0.33 dB/km at a wavelength of 1380 nm, by use of the method, which is disclosed in the patent application of Japan, published under No. Hei 11-171575. This method refers to the method of manufacturing a shell on the base, made in the form of a tube made of quartz glass, and the advantage of this method is to reduce the manufacturing cost by using the basics, made in the form of a tube made of quartz glass.

However, there was a problem, due to the presence of bubbles remaining between the rod core and the tube made of quartz glass.

In addition, the quality of optical fibers depends on such factors as, for example, the concentration of HE or curvature of the tube made of quartz glass, so there was the problem of the need to ensure continuous and extremely strict quality control. As a result, this led to a decrease in productivity (ratio of output products) and, therefore, it was uselicenseserver problem, consisting in the fact that losses have increased due to diffusion of hydrogen from the outside. To date, however, there was no proper measures to counter this phenomenon.

The INVENTION

The present invention was created in view of the above problems. The aim of the present invention is to provide a method of manufacturing a single-mode optical fiber, which has a lower initial losses in the spectral range of 1380 nm and can maintain a lower level of losses in the spectral range of 1380 nm than in conventional optical fiber, even in the case of penetration of hydrogen from the outside due to the diffusion.

To solve the above problems according to the first features of the present invention, a method for manufacturing a single-mode optical fiber that includes a stage, which is made of a glass rod having a core in which the refractive index is higher, and the first part of the shell, in which the refractive index is lower than in the core; stage, during which the deposition of, for example, particles of SiO2from the gas phase on (around) the outer periphery (i.e., circumferential peripheral surface) of the glass is of a glass preform; and the stage during which perform an operation of drawing a glass preform for manufacturing an optical fiber, where a value of D/d, i.e., the ratio of the diameter D of the first part of the shell to the diameter d of the core, is in the range from 4.0 to 4.8; the concentration of HE in the core, in the first part of the shell and the second part does not exceed 0.1 million shares.

Through this way you can even more reduce the number of bubbles arising at the interface between the core and the shell or between the first part of the shell and the second part of the shell, as compared with the case in which in is used as a base tube made of quartz glass. It is easy to perform the dehydration of the porous soot (i.e., a layer of ultra-fine precipitated particles of silicon dioxide), the formation of which carry the deposition from the gas phase; therefore, there is a possibility to control or adjust the desired image concentration. Moreover, since the quartz tube is not used, then there are no problems caused by the bending of the rod core and shell, made in the form of a tube made of quartz glass; consequently, increases productivity (ratio of output of indelibility.

According to other features of the present invention, a method for manufacturing a single-mode optical fiber, characterized in that it contains: stage, which is made of a glass rod having a core in which the refractive index is higher, and the first part of the shell, in which the refractive index is lower than in the core; stage, during which the deposition of, for example, particles of SiO2from the gas phase on (around) the outer periphery (i.e., circumferential peripheral surface) of the glass rod to create the second part of the shell and bake (annealed) glass rod for manufacturing a glass preform; and stage, during which perform an operation of drawing a glass preform for manufacturing an optical fiber, where a value of D/d, i.e., the ratio of the diameter D of the first part of the shell to the diameter d of the core, satisfies the condition D/d>4,8; the concentration of HE in the core and the first part of the shell does not exceed 0.1 million shares; and the concentration of IT in the second part of the membrane does not exceed 100 ppm.

According to the third features a method of manufacturing a single-mode optical fiber, this fiber has a spectrum in the range of 1380 nm to be 0.35 dB/km

In this case, the peak (losses) in the spectral range of 1380 nm is small, and both edges of the spectral range can be used for optical communication. Moreover, since it is possible to maintain the loss in the spectral range of 1380 nm after hydrogen diffusion below 0,35 dB/km, there is a possibility to put a single-mode optical fiber with low loss in the spectral range of 1380 nm in the presence of hydrogen diffusion and low-cost.

According to fourth features of the method of manufacturing a single-mode optical fiber drawing process used to manufacture the optical fiber, the operation of drawing the glass preform is performed by using the device drawing with annealing device.

Through this way you can maintain a low level concentrations arising radical SiO. Therefore, there is a possibility of making such a single-mode optical fiber, where the loss in the spectral range of 1380 nm does not increase even when the penetration of hydrogen by diffusion from the outer side (outside) of the optical fiber, which ensures its efficiency and reliability during Alekna annealing device contains a furnace with an inclined heating zone and the tube annealing.

According to sixth features of the method of manufacturing a single-mode optical fiber device of the annealing gas environment for annealing is any of the following environments: air, argon (ar), nitrogen (N2) or their mixture.

According to the seventh features of the present invention a single-mode optical fiber is manufactured by a manufacturing method in accordance with any of the above features of the present invention from the first to the sixth.

As explained above, according to the present invention by forming a glass preform by a vapor deposition of SiO2forming a second portion of the sheath around the outside of the outer circumferential peripheral surface of the glass rod containing the core and the first portion of the shell may be an optical fiber by performing the operation of drawing the glass preform. Therefore, the possibility exists to an even greater extent to reduce the number of bubbles arising at the interface between the core and the shell or between the first part of the shell and the second part of the shell, as compared with the case in which in is used as a base tube made of quartz glass. In addition, the village is the R particles of silicon dioxide, at which carry out the deposition from the gas phase, it is possible to create an optical fiber by adjusting the desired image concentration contained hydroxyl HE-ions. Moreover, since the quartz tube is not used, then there are no problems caused by the bending of the rod core and tube made of quartz glass, which forms a shell. So you can increase productivity (the ratio of the yield of the product), therefore, it is possible to make single-mode optical fiber with low cost.

Moreover, the optical fiber is made so that the ratio D/d, i.e., the relationship of the diameter D of the first part of the shell to the diameter d of the core, ranged from 4.0 to 4.8, and the concentration of HE in the core, in the first part of the shell and in the second part of the membrane is not more than 0.1 million shares, to the value of the ratio D/d, i.e., the ratio of the diameter of the first portion of the shell to the core diameter, to satisfy the condition D/d>4,8, the concentration of HE in the core and the first part of the shell is not more than 0.1 million shares, and the concentration of IT in the second part of the membrane does not exceed 100 ppm. Therefore, there is a maybe, since the peak (maximum loss) in the spectral range of 1380 nm is small, it becomes possible to use ranges, located on either side of this peak, for optical communication.

Moreover, because of the possibility to limit the loss in the spectral range of 1380 nm so that after diffusion of hydrogen they do not exceed 0,35 dB/km, it is possible to set a single-mode optical fiber with low loss in the spectral range of 1380 nm, even in the presence of hydrogen diffusion and low-cost.

Besides, at the stage of extrusion, carried out by the operation of extrusion using a pulling device containing annealing device, it is possible to restrict the generation of radical SiOthus, to ensure the lowest levels. Therefore there is only a small increase in losses in the spectral range of 1380 nm, due to the presence of hydrogen, even when the hydrogen penetrates by diffusion from the external side optical fiber, hence there is the possibility of creating a single-mode optical fiber, which keeps the efficiency and reliability during long is the rotary above method of manufacture, not exceed in the spectral range of 1380 nm values at 0.31 dB/km, and the peak in the spectral range of 1380 nm can be small. Therefore, for optical communication, you can use both sides of the spectral range. Moreover, because of the possibility of loss in the spectral range of 1380 nm so that after diffusion of hydrogen they do not exceed 0,35 dB/km, the optical connection in the spectral range of 1380 nm can be realized with low loss even in the presence of hydrogen diffusion.

BRIEF DESCRIPTION of DRAWINGS

In Fig.1 shows the cross section of the glass preform from which to create a single-mode optical fiber according to the present invention.

In Fig.2 shows an example of the pulling device, which is used in the method of manufacturing a single-mode optical fiber according to the present invention.

In Fig.3 shows another example of the pulling device, which is used in the method of manufacturing a single-mode optical fiber according to the present invention.

In Fig.4 shows an example of a conventional pulling device.

DETAILED description of the INVENTION

The following is an explanation of the present invention with reference to the drawings.

In Fig.1 image is SNO present invention.

In Fig.1 number 1 is the core, which has a high refractive index. Number 2 is the first part of the membrane, which is located around the outer periphery (ring peripheral surface) of the core 1 and has a lower refractive index than the core 1. Number 3 marked the second part of the shell that has the same refractive index as the first part 2 of the shell.

Below is a description of the method of manufacturing a glass preform and the optical fiber, which is created by performing the operation of drawing the glass preform.

First get porous soot, i.e., the layer of ultra-fine precipitated particles of silicon dioxide, containing a core 1 having a high refractive index, and the first portion of the shell having a lower refractive index than the refractive index of the core 1, through the use of conventional devices of the axial vapor deposition (hereinafter referred to as device OOLL (from the English. Vapor phase axial deposition (VAD)). The core 1 is produced by deposition of particles GeO2and particles of SiO2. The first part 2 of the shell is obtained by deposition of particles of SiO2. The difference And the refractive indices of the core 1 and the first part 2 obuchenie diameter of the first part 2 of the shell (with diameter D) to the diameter of the core 1 (with diameter d), in the preferred embodiment, should be less than about 4.0. The reason why the value of the ratio D/d in the preferred embodiment, should have such a value is as follows.

In the case when the ratio D/d takes a value in the range from 4.0 to 4.8, there is a possibility of limiting the source of losses in the spectral range of 1380 nm so that they do not exceed at 0.31 dB/km, by limiting the concentration of HE in the second part 3 shell size not exceeding 0.1 million shares. In the case when the value D/d satisfies, for example, the condition D/d>4,8, there is the ability to limit losses in the spectral range of 1380 nm so that they do not exceed at 0.31 dB/km, and it is not necessary to perform the dehydration with the use of gaseous chlorine, because it has only a small effect due to the concentration of HE in the second part 3 of the shell.

As explained above, if there is the possibility of such loss in the spectral range of 1380 nm, so they are not exceeded at 0.31 dB/km, it is possible to realize optical communication using a wider spectral range.

However, if the value D/d condition D/d<4,0, Exodus part 3 of the shell is limited to the value, not exceeding 0.1 million shares, and therefore, the purpose of the present invention cannot be achieved.

As described above, the preferred option is one in which the value of the ratio D/d, representing a ratio of the diameter D of the first part 2 of the shell to the diameter d of the core 1 must be in the range from 4.0 to 4.8, and in which the concentration of HE in the core 1, in part 2 of the shell and the second part 3 of the shell should not exceed 0.1 million shares.

Another preferred variant is one in which the value of the ratio D/d, through which indicate the ratio of the diameter D of the first part 2 of the shell to the diameter d of the core 1, must satisfy the relation D/d>4,8, the concentration of HE in the core 1 and the first part 2 of the shell should not exceed 0.1 million shares, and the concentration of IT in the second part 3 of the shell shall not exceed 100 ppm.

Then carry out the dehydration and sintering of the porous soot, i.e., a layer of ultra-fine precipitated particles to create a glass rod. In this case, if the value of D/d is in the range from 4.0 to 4.8, the dehydration operation is performed in the environment of gaseous chlorine or in a mixed environment of gaseous chlorine and gaseous/176.gif">C.

The second part 3 of the shell is formed by performing deposition of particles of SiO2from the gas phase on the outer side of the above glass rod. The thickness of the second part 3 shell set in accordance with the diameter, which creates a glass rod. For example, if the diameter of the optical fiber is 125 micrometers (μm), the deposition of particles of SiO2from the gas phase on the outer side of the workpiece can be performed so that the thickness of the second part 3 of the shell was equal to 43 μm or less. When the thickness of the second part 3 of the shell exceeds 43 μm, it is not preferable because it increases the initial loss in the spectral range of 1380 nm.

In that case, if according to the value of D/d you must complete dehydration, the dehydration of the glass rod on the outer side of the second deposition portion 3 of the shell from the gas phase, is carried out in a medium of gaseous chlorine or in a mixed environment of gaseous chlorine and gaseous oxygen. The sintering operation to create a glass preform perform in an environment of gaseous helium at a temperature of 1450C.

After that create the optical fiber by you the emer if the rate of extrusion is 600 meters per minute (m/min) or more, immediately after the operation of pulling perform the cooling of the optical fiber. Therefore, the preferred option is the one that uses the pulling device containing annealing device located at the outlet of the furnace for drawing.

An example of a pulling device, which is used in the drawing process shown in Fig.2 and Fig.3.

In Fig.2 number 10 indicated a furnace for drawing. By means of the heater 12 in the furnace 10 for pulling perform an operation of drawing a glass preform 11, which receive the optical fiber 13 without coating. After cooling the optical fiber 13 without coating in the tube 14 of annealing on the optical fiber 13 without coating applied to the polymer through the device causing the polymer, resulting receive one strand or core optical fiber. On the surface of the tube 14 annealing the formed hole 15 for gas supply. As the cooling gas may be air, argon (ar), nitrogen (N2or any mixture of these gases.

In addition, the device of the drawing, depicted in Fig.3, instead of the tube 14 annealing, which is shown in Fig.2, provided with a furnace with a sloping area 16 heating to cooling core 13 the optical position of Fig.2. The preferred option is the one in which the furnace with a sloping area 16 of the heating maintains a lower temperature than the temperature of the heater 12 in the node of the furnace 10 for extrusion, for example from 400With up to 1800C. the Most preferred option is the one in which the inclined furnace can change the temperature in different areas present within it.

In contrast, in Fig.4 shows a conventional oven for extrusion, in which there is no annealing device. Through each of the item numbers in Fig.4 indicated the device, which are indicated by the same item number in Fig.2. When using such a furnace for drawing in which there is no annealing device, the effect of annealing is insufficient, and the radicals SiOremain in the optical fiber. Therefore, after the diffusion of hydrogen increased loss in the spectral range of 1380 nm.

After creating the optical fiber in the above manner, the optical fiber is exposed to gaseous hydrogen with a partial pressure of 0.01 atmosphere within ten days. Then carry out the measurement of the losses after the diffusion of hydrogen. In that case, if the pot is LEM with the implementation of optical communication using a wide spectral range. However, if losses in the spectral range of 1380 nm after hydrogen diffusion exceed 0,35 dB/km, the first goal of the present invention is impossible.

Below are examples of single-mode optical fiber that is created through the above manufacturing method.

Example 1

Was produced glass preform in which the ratio D/d, through which indicate the ratio of the diameter D of the first part 2 of the shell to the diameter d of the core 1, is equal to 4.3, and the concentration of IT in the second part 3 of the shell does not exceed 0.1 million shares. After this was made single-mode optical fiber by the operation of pulling the unit pulling with annealing device. Losses in the spectral range of 1380 nm was 0,285 dB/km, This value is smaller than at 0.31 dB/km; therefore, the intermediate value losses in the spectral range of 1380 nm is acceptable. It was also performed a measurement of the losses in the spectral range of 1380 nm after exposure to hydrogen. As a result of loss was 0,320 dB/km, This value is less than 0,35 dB/km, and the loss in the spectral range of 1380 nm, obtained as the final result, in example 1, allauto denote the ratio of the diameter D of the first part 2 of the shell to the diameter d of the core 1, equal to 4.9, and the concentration of IT in the second part 3 of the shell is equal to 40 million shares or less. After this was made single-mode optical fiber by the operation of pulling the unit pulling with annealing device. Losses in the spectral range of 1380 nm was 0,308 dB/km, This value is smaller than at 0.31 dB/km, so the intermediate value losses in the spectral range of 1380 nm is acceptable. It was also performed a measurement of the losses in the spectral range of 1380 nm after exposure to hydrogen. As a result of loss was 0,341 dB/km, This value is less than 0,35 dB/km; therefore, the loss in the spectral range of 1380 nm, obtained as the final result, in Example 2, are acceptable.

Example 1 for comparison,

Was produced glass preform in which the ratio D/d, through which indicate the ratio of the diameter D of the first part 2 of the shell to the diameter d of the core 1, is equal to 4.1, and the concentration of IT in the second part 3 of the shell does not exceed 0.1 million shares. After this was made single-mode optical fiber by the operation of extrusion using a pulling device, which was not supplied with the unit is m, therefore, the intermediate value losses in the spectral range of 1380 nm is acceptable. It was also performed a measurement of the losses in the spectral range of 1380 nm after exposure to hydrogen. However, the resulting net loss was 0,359 dB/km, This value exceeds 0,35 dB/km, and the loss in the spectral range of 1380 nm, obtained as the final result, in example 1, for comparison, are unacceptable.

Example 2 for comparison,

Was produced glass preform in which the ratio D/d, through which indicate the ratio of the diameter D of the first part 2 of the shell to the diameter d of the core 1, is equal to 3.8, and the concentration of IT in the second part 3 of the shell does not exceed 0.1 million shares. After this was made single-mode optical fiber by the operation of extrusion using a pulling device, which was not provided with a device annealing. Losses in the spectral range of 1380 nm was 0,320 dB/km, This value exceeds at 0.31 dB/km; therefore, the intermediate value losses in the spectral range of 1380 nm is unacceptable. It was also performed a measurement of the losses in the spectral range of 1380 nm after exposure to hydrogen. However, the obtained result pocenia as the final result in example 2 for comparison, are unacceptable.

Example 3 for comparison

Was produced glass preform in which the ratio D/d, through which indicate the ratio of the diameter D of the first part 2 of the shell to the diameter d of the core 1, is equal to 4.3, and the concentration of IT in the second part 3 of the shell is equal to 35 million shares. After this was made single-mode optical fiber by the operation of extrusion using a pulling device, which was not provided with a device annealing. Losses in the spectral range of 1380 nm was MX 0.317 dB/km, This value exceeds at 0.31 dB/km, so the intermediate value losses in the spectral range of 1380 nm is unacceptable. It was also performed a measurement of the losses in the spectral range of 1380 nm after exposure to hydrogen. However, the resulting net loss was 0,365 dB/km, This value exceeds 0,35 dB/km, and the loss in the spectral range of 1380 nm, obtained as the final result in example 3 for comparison, are unacceptable.

The results obtained in the above examples, are given in Table 1.

By means of the method of manufacturing a single-mode optical fiber, which is shown in privavcy 11, created by deposition from the gas phase the second part of the shell, is made of particles of SiO2on the outer circumferential peripheral surface of the glass rod containing the core 1 and the first part 2 of the shell, and the operation of drawing the glass preform 11. Through this method of manufacture can significantly reduce the number of bubbles arising at the interface between the core and the shell or between the first part 2 of the shell and the second part 3 of the shell. Moreover, it is easy to perform the dehydration of the porous layer of ultra-fine precipitated particles of silicon dioxide, by deposition from the gas phase; therefore, there is a possibility of creating the optical fiber when the regulation is desirable, concentrations of IT.

Moreover, since the quartz tube is not used, then there is no impact due to, for example, by bending a tube made of quartz glass, which forms the core of the core or shell. Therefore, increases productivity (the ratio of the yield of the product), and you can create a single-mode optical fiber with low cost.

Moreover, optical fiber is the diameter d of the core 1, ranged from 4.0 to 4.8, and the concentration of HE in the core 1, in part 2 of the shell and the second part 3 of the shell does not exceed 0,1 million shares; to the value of the ratio D/d, i.e., the relationship of the diameter of the first portion of the shell to the core diameter, to satisfy the condition D/d>4,8, the concentration of HE in the core 1 and the first part 2 of the shell is not more than 0.1 million shares, and the concentration of IT in the second part 3 of the shell does not exceed 100 ppm. Therefore it is possible to limit the sources of losses in the spectral range of 1380 nm so that they do not exceed at 0.31 dB/km in addition, since the peak (losses) at the wavelength of 1380 nm is small, you can use for optical communication at both sides of the spectral range.

Moreover, since it is possible to limit the loss in the spectral range of 1380 nm so that after diffusion of hydrogen they do not exceed 0,35 dB/km, there is the possibility of supplying the market with a single-mode optical fiber with low loss in the spectral range of 1380 nm and having low cost.

It is also possible to restrict the generation of radical SiOthus, to ensure that Nobunaga the annealing device, which is used in the drawing process. Therefore, there is a possibility of supplying the market with a single-mode optical fiber with low loss in the spectral range of 1380 nm, and also keeping the performance and reliability when used for a long period of time even in the case of penetration of hydrogen from the outside due to the diffusion.

Besides the initial loss in single-mode optical fiber, which is created by the above manufacturing method, do not exceed at 0.31 dB/km Therefore, the peak (losses) in the spectral range of 1380 nm can be small, so you can use both sides of the peak for optical communication. Also, it is possible to limit the loss in the spectral range of 1380 nm so that after diffusion of hydrogen they do not exceed 0,35 dB/km Therefore, it is possible to carry out optical communication in the spectral range of 1380 nm, even in the presence of hydrogen diffusion.

Claims

1. A method of manufacturing a single-mode optical fiber containing phase, which form a glass rod having a core and a first portion of the shell having a bol is th shell on the first part of the shell, is sintered glass rod having first and second parts of the shell, to obtain a glass preform, and perform an operation of drawing a glass preform for obtaining an optical fiber, in which the ratio of the diameter D of the first part of the shell to the diameter d of the core is in the range from 4.0 to 4.8, and the concentration of HE in the core, the first part of the shell and the second part of the shell not higher than 0.1 million shares.

2. The method according to p. 1, in which the original loss in the spectral range of 1380 nm is not exceeded at 0.31 dB/km, and the loss in the spectral range of 1380 nm after diffusion of hydrogen does not exceed 0,35 dB/km

3. The method according to p. 2, in which at the stage of the drawing operation of the drawing of the glass preform is carried out by means of a device drawing with annealing device.

4. The method according to p. 3, in which the annealing device contains a furnace with an inclined heating zone and the tube annealing.

5. The method according to p. 4, in which the device of the annealing gas environment for annealing is any of the following environments: air, argon (ar), nitrogen (N2) or their mixture.

6. A method of manufacturing a single-mode optical fiber containing phase, which form a glass rod having a core and a first portion of the shell, have the ROI part of the shell on the first part of the shell, is sintered glass rod having first and second parts of the shell, to obtain a glass preform, and perform an operation of drawing a glass preform for obtaining an optical fiber, in which the ratio of the diameter of the first portion of the shell to the core diameter is more than 4.8, the concentration of HE in the core and the first part of the shell not higher than 0.1 million shares, and the concentration of IT in the second part of the membrane does not exceed 100 ppm.

7. The method according to p. 6, in which the original loss in the spectral range of 1380 nm is not exceeded at 0.31 dB/km, and the loss in the spectral range of 1380 nm after diffusion of hydrogen does not exceed 0,35 dB/km

8. The method according to p. 7, in which at the stage of the drawing operation of the drawing of the glass preform is carried out by means of a device drawing with annealing device.

9. The method according to p. 8, in which the annealing device contains a furnace with an inclined heating zone and the tube annealing.

10. The method according to p. 9, in which the device of the annealing gas environment for annealing is any of the following environments: air, argon (ar), nitrogen (N2) or their mixture.

11. Single-mode optical fiber made by the method of manufacturing according to any one of paragraphs.1-5.

12. Single-mode optical

 

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FIELD: optical fibers production techniques.

SUBSTANCE: the invention is dealt with optical fibers production techniques. For production of optical fiber billets particles of a glass first are synthesized in the oxygen-hydrogenous torch flame. Production a porous billet is made by settling the particles in a radial direction on the external surface of the parent element with following sintering of the porous billet. At that definite ratio between the speed of flow of a starting gaseous material or a gas mixture consisting of the starting gaseous material and an additive gas and a speed of flow of a noble gas should be maintained. The torch has four channels for feeding of gases. The sizes of channels of the torch ensure the definite ratio of the indicated speeds.

EFFECT: The invention ensures an increase of quality of the optical fiber billets.

4 cl, 2 dwg

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