KR100701727B1 - Method for Decreasing PMD of an Optical Fiber Using Heat Source and Apparatus for Manufacturing an Optical Fiber Using the Method - Google Patents

Abstract

The present invention relates to the manufacture of optical fibers, and more particularly, to a method and apparatus for reducing the polarization mode dispersion (PMD) of an optical fiber. According to the present invention, at least one heat source is disposed in the circumferential direction of the stranded spiral optical fiber, thereby forming a nonuniform temperature gradient in the circumferential direction of the spiral fiber by the heat source, and a nonuniform temperature gradient formed in the circumferential direction. By cooling the spliced fiber and causing a change in the internal structure of the optical fiber due to the cooling speed difference, the same effect as applying spin to the optical fiber without physical contact is obtained, thereby reducing the PMD of the optical fiber.

Optical fiber, polarization mode dispersion, PMD, birefringence, heat source, circumferential temperature gradient

Description

Method for Decreasing PMD of an Optical Fiber Using Heat Source and Apparatus for Manufacturing an Optical Fiber Using the Method

The following drawings attached to this specification are illustrative of preferred embodiments of the present invention, and together with the detailed description of the invention to serve to further understand the technical spirit of the present invention, the present invention is a matter described in such drawings It should not be construed as limited to

1 is a schematic diagram of an optical fiber manufacturing apparatus (drawing apparatus) according to a preferred embodiment of the present invention.

2 is a schematic diagram illustrating a method of applying non-uniform heat in the circumferential direction of an optical fiber according to the principles of the present invention, in the case of having one heat source rotating in the circumferential direction of an optical fiber according to an embodiment of the present invention. .

3 is a partial perspective view and a block diagram showing a specific configuration of the embodiment shown in FIG.

4 is a schematic diagram illustrating a method of applying non-uniform heat in the circumferential direction of an optical fiber according to the principles of the present invention, when a plurality of heat sources are provided in the circumferential direction of an optical fiber according to another embodiment of the present invention.

FIG. 5 is a schematic diagram illustrating a method of applying non-uniform heat in the circumferential direction of an optical fiber according to the principles of the present invention when a plurality of heat sources are provided in the circumferential direction of an optical fiber according to another embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

101: optical fiber base material 102: cutting line

103: bare optical fiber 104: outer diameter measuring instrument

105: cooling device 106: coating device

107: curing device 108: driver (capstan)

109: winding device 110: heating device

120, 120 ', 120 ": control unit

The present invention relates to the manufacture of optical fibers, and more particularly, to a method and apparatus for reducing the polarization mode dispersion (PMD) of an optical fiber.

Theoretically circular symmetric single mode optical fibers have two independent, mutually canceling orthogonal polarization modes. In general, the electric field of light propagating through an optical fiber can be seen as a linear superposition of these two polarization eigenmodes. In practice, single-mode optical fibers are canceled out of these two polarization modes by incomplete elements such as symmetrical lateral stresses or eccentricity of circular cores. These two modes propagate with different phase velocities, thereby propagating the two polarization modes with different propagation constants β ₁ and β ₂ . This difference in propagation constants is referred to as birefringence (Δβ), and the increase in birefringence means an increase in the speed difference between the two polarization modes. The differential time delay between two polarization modes is called polarization mode dispersion (hereinafter abbreviated as "PMD"), the presence of which makes it difficult to transmit high speed or analog data.

On the other hand, several methods for reducing PMD have been proposed.

First, WO83 / 00232, Japanese Patent Laid-Open No. 8-59278, Japanese Patent Laid-Open No. 7-69665, US Patent No. 5,943,466, US Patent No. 6,240,748, US Patent No. 5,298,047 and US Patent No. 6,076,376 As a method disclosed in the present invention and the like, it is a method of reducing PMD by twisting the optical fiber to a predetermined pitch when the optical fiber is drawn from the optical fiber base material so that gradual compensation is made due to the relative delay between polarization modes. However, this method twists the optical fiber along with the coating material coated on the optical fiber or the fiber surface to be edged, so that there is elastic torsional stress in the finished optical fiber, which deteriorates the optical loss characteristic, another important characteristic of the optical fiber. In particular, in the case of providing continuous spin in one direction, a separate re-spooling device is required to eliminate the twist. In addition, since the physical contact is used to apply spin to the optical fiber, the coating property of the optical fiber is weakened, which is likely to cause disconnection of the optical fiber, and mechanical failure occurs on the surface of the optical fiber, thereby weakening the strength of the optical fiber. Furthermore, in order to cope with the gradually increasing edge speed, the rotational speed of the base material or the optical fiber must be dramatically increased, which is commercially impractical.

Secondly, the method disclosed in Korean Patent Laid-Open Publication No. 2002-63409, which provides a gas flow path in the circumferential direction of the optical fiber inside the melting furnace for the edge line, and ejects the gas sequentially and periodically to periodically induce fine deformation in the optical fiber. How to control. In theory, however, the best conditions for the PMD of an optical fiber are when the base material is ideally manufactured, that is, when the core and cladding layers are perfectly circular, and in particular with the base material exactly centered, which is rather the optical fiber. It is very doubtful that the actual PMD will be improved since it would make these conditions worse by shaking.

Third, the method disclosed in U.S. Patent No. 5,992,181 is a method of controlling PMD by changing the characteristics of the optical fiber base material by irradiating the optical fiber base material periodically or non-periodically with a laser light of a specific wavelength band, especially a short wavelength band. However, the disadvantage of this method is that a high power laser of several hundred watts or more should be used to irradiate the laser light to change the base material properties of the optical fiber. The high power laser is expensive and the size of the device is too large to be mounted on the actual optical fiber edge device. it's difficult. Moreover, it is advantageous to rotate this laser light around the optical fiber for the adjustment of the PMD, which is practically very difficult to implement, and the PMD improvement effect is insignificant compared to the method of applying the spin.

Fourth, the method disclosed in Patent No. 417000 is a method of reducing PMD by removing residual stress remaining in an optical fiber by locally and periodically applying heat treatment using an auxiliary heat source fixed to one side of an optical fiber to be drawn. However, this method has a disadvantage in that the reaction speed is slow, which does not correspond to the increase in the cutting speed, and does not provide an effect such as applying spin in the circumferential direction of the optical fiber, which is advantageous for reducing the PMD.

As described above, various methods have been proposed for PMD reduction, but there is still a need for a PMD reduction method that is effective, practical, and suitable for high speed and mass production of optical fibers.

An object of the present invention is to provide a method capable of effectively and practically reducing PMD without physical contact with an optical fiber and an optical fiber manufacturing apparatus using the same.

The present inventors form a non-uniform temperature gradient in the circumferential direction of the stranded spiral optical fiber and cool the spiral fiber in which the temperature gradient is formed to cause a change in the internal structure of the optical fiber due to the cooling rate difference, thereby preventing the optical fiber without physical contact. The inventors have found out that the PMD of the optical fiber can be reduced by the same effect as applying spin to, and the present invention has been completed.

That is, the method of improving the PMD of the optical fiber according to an aspect of the present invention, the step of applying a non-uniform heat in the circumferential direction of the spiral fiber to the spiral optical fiber which is carried out from the optical fiber base material; And cooling the spiral fiber to which the non-uniform heat is applied in the circumferential direction. The internal structure of the spiral fiber in the cooling step by the circumferential temperature gradient of the spiral fiber formed by the non-uniform heating in the circumferential direction. This change allows the polarization mode dispersion of the completed optical fiber to be improved.

Here, the step of applying the non-uniform heat in the circumferential direction, is performed by rotating at least one heat source disposed in the circumferential direction of the filamentary fiber in the circumferential direction, or arrange a plurality of heat sources in the circumferential direction of the filamentous fiber And by operating the plurality of heat sources sequentially or out of sequence.

In addition, an optical fiber manufacturing apparatus according to another aspect of the present invention, means for cutting the optical fiber base material to form a spiral optical fiber; At least one heat source rotatably disposed in the circumferential direction of the spiral fiber to form a non-uniform temperature gradient in the circumferential direction by applying uneven heat in the circumferential direction; Control means for controlling power and rotational speed and / or direction of the at least one heat source; Means for cooling the filamentous fiber in which the non-uniform temperature gradient is formed in the circumferential direction; Means for coating at least one coating layer around the cooled spliced fiber; Capstan for controlling the cutting speed of the optical fiber; And a winding bobbin for winding the optical fiber passing through the capstan to the bobbin.

Furthermore, an optical fiber manufacturing apparatus according to another aspect of the present invention includes means for cutting the optical fiber base material to form spiral fiber; A plurality of heat sources arranged in the circumferential direction of the filamentous fiber to form a non-uniform temperature gradient in the circumferential direction by applying uneven heat in the circumferential direction; Control means for controlling the operation of the plurality of heat sources; Means for cooling the filamentous fiber in which the non-uniform temperature gradient is formed in the circumferential direction; Means for coating at least one coating layer around the cooled spliced fiber; Capstan for controlling the pulling speed of the optical fiber; And a winding bobbin for winding the optical fiber passing through the capstan to the bobbin.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the present specification and claims should not be construed as being limited to the common or dictionary meanings, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

1 shows a schematic configuration of an optical fiber manufacturing apparatus according to the present invention.

Referring to FIG. 1, the optical fiber manufacturing apparatus (drawing apparatus) 100 of the present invention includes a heating apparatus 110 and a control apparatus 120 as a furnace 102, an outer diameter measuring instrument 104, and a PMD reducing means. ), A cooling device 105, a coating device 106, a curing device 107, a driver (capstan) 108, and a winding device (winding bobbin) 109.

In the apparatus shown in FIG. 1, the optical fiber base material 101 is heated to a high temperature in the edge line 102, and is drawn to the bare optical fiber 103 from the neck-down point of the softened base material. The edged spiral fiber 103 is heated unevenly in the circumferential direction by the heating device 110 controlled by the control device 120 through the outer diameter measuring unit 104, thereby forming a non-uniform temperature gradient in the circumferential direction, The cooling unit 105 is fixed while cooling. At this time, the cooling fiber having a cooling rate difference according to the temperature gradient has an internal structure deformed in the circumferential direction. The cooled spiral fiber is coated at least once with an ultraviolet curable resin in the coating device 106, and the coated optical fiber coated in the coating device is cured in the curing device 107, and then the driver 108 for controlling the cutting speed of the optical fiber. It is conveyed to the odor device 109 through the odor.

The above-described optical fiber manufacturing apparatus is substantially the same as the general tower-type optical fiber cutting apparatus except for the heating device 110 and the control device 120, so the following specific configuration of the heating device 110 and the control device 120 The present invention will be described in detail by explaining operations and operations, and detailed description of the remaining components will be omitted.

2 and 3 illustrate the configuration of a heating apparatus and a control apparatus according to an embodiment of the present invention. The PMD improvement method and the optical fiber manufacturing apparatus of the present embodiment will be described in detail with reference to FIGS. 2 and 3.

In the present embodiment, the heating device 110 is disposed so that one heat source 111 is rotatable in the circumferential direction of the filamentary fiber 103. Specifically, the heat source 111 may be made of, for example, a heating wire such as a nichrome wire that emits red light or infrared light having a wavelength of 600 nm or more. Such a heating element can be made smaller in size, which makes it easier to apply to an optical fiber edge device than a conventional laser beam irradiation method, and because it is an electric system, it is operated by controlling the on / off control and the applied power. Overheating can be controlled easily.

In addition, the heat source 111 is fixedly disposed to face the light fiber 103 inside the driven pulley 116 to transmit the rotational force of the motor 119 through the rotational force transmission means such as the active pulley 117 and the belt 118. It is arranged to rotate in the circumferential direction of the filamentary fiber 103 by being supplied. In FIG. 3, reference numerals 112 and 113 are rotating electrodes of the heat source 111 fixed to the upper and lower surfaces of the driven pulley 116 made of an insulator and rotating together with the driven pulley 116, and 114 and 115 are electrodes of the heat source ( 112 and 113, a fixed electrode in the form of a brush for applying a current.

In addition, a heat source power supply device 123 is connected to the heat source 111, and the control device 200 supplies an ON / OFF control signal and a power value (power) control signal of power supplied to the heat source 111 to supply the heat source power. By applying to the device 123, the operation and heat generation amount of the heat source 111 is controlled. On the other hand, the motor power supply 124 is connected to the motor 119, the control device 200 by applying a motor on / off control signal, a motor speed control signal, and a rotation direction control signal, Control operation, direction and speed of rotation. Therefore, by adjusting the power applied to the motor 119, it is possible to easily control the rotational movement of the motor, so-called modulation is possible. In other words, compared to a configuration in which the optical fiber is applied to spin to reduce the PMD, the rotational speed, direction, and period of the motor are particularly provided while giving an effect such as applying spin by rotating a heat source linked to the motor without physical contact with the optical fiber. It is possible to give as many spins as possible within a given bit length by simply adjusting the back, and furthermore, modulation that is known to have an excellent effect on PMD improvement by changing the speed and direction of the spins aperiodically. .

In addition, the control device 200 may be provided with a user interface 121 so that a user may input information for controlling power or movement of the heat source 111 and the motor 119. In addition, the control device 200 may be provided with a display device 122 to display information input by a user or an operating state of the heat source 111 or the motor 119. Therefore, the user can easily control the heat source 111 and the motor 119. Specifically, the user can, with respect to the heat source 111, ① maintain a constant power (i.e. calorific value), ② change the power in the form of a predefined periodic function, ③ change the power aperiodically, ④ The heat source can be controlled by turning on / off the power periodically or aperiodically or by combining the above ① to ④. Similarly, the motor can be rotated at a constant speed in the form of a predefined cycle function. The motor 119 may be controlled by a method of changing the rotation speed, ⑦ a method of changing the rotation speed aperiodically, ⑧ a method of changing the rotation direction periodically or aperiodically, or a combination of the above ⑤ to ⑧. .

Next, a mechanism for reducing the PMD of the optical fiber by using the apparatus of the present embodiment configured as described above will be described.

When the helical fiber 103 drawn from the optical fiber edge 102 enters the heating device 110 where the calorific value, the rotational speed and the direction are controlled by the control device 120, in the circumferential direction of the helical fiber 103. Uneven heat is applied to create a temperature gradient in the circumferential direction. In this way, when the optical fiber 103 having a temperature gradient formed in the circumferential direction enters the cooling device 105, a change occurs in the internal structure of the optical fiber during cooling due to a difference in cooling rate according to the temperature gradient. This change in the internal structure of the fiber leads to PMD reduction.

Meanwhile, in the above-described embodiment, the case where the heating device 110 is provided with one heat source 111 has been described. However, the present invention is not necessarily limited thereto. For example, by arranging two or three or more heat sources symmetrically in the driven pulley 116 of FIG. 3, even when the cutting speed is high speed, it can be sufficiently coped.

In addition, although the active pulley 117, the driven pulley 116, and the belt 118 are illustrated and described as an example of the rotational force transmitting means in the above-described embodiment, power transmission means such as gears or chains may be adopted. Of course.

Further, in the above-described embodiment, the heat source 111 is shown and described as being fixed in the driven pulley 116 so as to be rotatable only in the circumferential direction of the optical fiber, but the heat source is, for example, an optical fiber by a linear reciprocating drive means such as a solenoid. It may be arranged to be retractable in the radial direction of 103. In this case, by advancing and retreating the heat source in the radial direction of the optical fiber, an effect similar to controlling the amount of heat generated by adjusting the power of the heat source can be obtained.

4 is a view schematically showing the configuration of a heating apparatus according to another embodiment of the present invention.

Referring to FIG. 4, the heating apparatus according to the present embodiment will be described with reference to differences from the above-described embodiment.

In the above-described embodiment, one heat source 111 is rotated along the circumferential direction of the optical fiber, but in the present embodiment, the plurality of heat sources 111a to 111d are fixedly arranged along the circumferential direction of the helical fiber 103 (Fig. 4 shows four heat sources arranged at approximately 90 degree intervals, but the number is not particularly limited). And, unlike the rotation of the heat source by the motor 119 of the above-described embodiment, the control device 120 'of the present embodiment is to turn on / off and power sequentially or non-sequentially for the plurality of heat sources (111a to 111d). By controlling, the same effect as rotating the heat source periodically or aperiodically in the above-described embodiment is obtained.

Therefore, in the present embodiment, similarly to the above-described embodiment, the non-uniform heating in the circumferential direction of the filamentary fiber 103 can be performed, and thus a temperature gradient can be given in the circumferential direction, thereby applying spin to the optical fiber without physical contact. The same effect can be obtained. Particularly, in the present embodiment, mechanical elements such as a motor or a pulley are not required, and thus the entire device can be easily implemented, and there is no mechanical failure due to the rotation of the heat source, thereby improving durability and reliability of the device.

On the other hand, the larger the number of the heat source (111a to 111d) disposed in the circumferential direction of the optical fiber 103 in the present embodiment can obtain a similar effect to the rotation of the heat source in the above-described embodiment, but the spatial limit according to the size of the heat source This can make it difficult to place a large number of heat sources. In this case, a large number of heat sources can be arranged without difficulty by arranging the plurality of heat sources helically along the axis of the optical fiber 103 without placing them on the same plane. When a plurality of heat sources are arranged in a spiral like this, in particular, it is possible to sufficiently cope with a high cutting speed.

Also, in the present embodiment, as in the above-described embodiment, all or part of the plurality of heat sources 111a to 111d may be arranged to be able to move forward and backward in the radial direction of the optical fiber. In particular, when all of the plurality of heat sources are arranged to be retractable in the radial direction of the optical fiber, the heat source may be periodically or non-periodically rotated by turning on all the heat sources during the cutting process and retreating the heat sources sequentially or non-sequentially with respect to the optical fiber. A similar effect can be obtained.

In addition, the plurality of heat sources 111a to 111d may be arranged to be spaced apart from the optical fiber 103 by the same distance, or may be arranged to have different separation distances. Although not illustrated in FIG. 4, the user interface and the display device may be connected to the control device 120 ′ as in FIG. 3.

5 is a view schematically showing the configuration of a heating apparatus according to another embodiment of the present invention.

Referring to FIG. 5, the heating apparatus according to the present embodiment will be described with reference to differences from the above-described embodiments.

The heating apparatus of the present embodiment includes the plurality of heat sources 111a to 111d as in the embodiment described with reference to FIG. 4. However, the heat sources 111a to 111d of the present embodiment are not fixed and are disposed on the rails 125a to 125d so as to be able to linearly reciprocate in the tangential direction of the optical fiber while being spaced apart from the optical fiber 103 by a predetermined distance. The linear motion of the heat sources 111a to 111d may be implemented by a gear method using, for example, a rack and pinion, or may be implemented using a solenoid.

In addition, the control device 200 ″ of the present embodiment controls linear reciprocating motions on the rails 125a to 125d as well as on / off or power of the respective heat sources 111a to 111d. Thus, the heat sources 111a to A similar effect to the rotation of the heat source can be obtained by simultaneously rotating 111d) in the same direction in the clockwise or counterclockwise direction, and furthermore, regularly or irregularly, without linearly moving the heat sources 111a to 111d in the same direction. It is also possible to linearly move in a non-constant direction (mixing clockwise and counterclockwise directions) to obtain more various modulation effects.

On the other hand, also in this embodiment, a plurality of heat sources can be arranged helically along the axis of the optical fiber 103 without being disposed on the same plane, and the separation distance of the heat sources 111a to 111d from the optical fiber 103 is the same or mutually. can be different. In addition, a user interface and a display device may be connected to the control device 120 ″.

As described above, according to the present invention, by using a relatively small and various controllable heat source, the same effect as applying spin to the optical fiber without twisting the optical fiber itself or physical contact can be obtained with a simple configuration.

Although the present invention has been described above by means of limited embodiments and drawings, the present invention is not limited thereto and will be described below by the person skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of the claims.

According to the present invention, it is possible to reduce the PMD in a non-contact manner without physically contacting the optical fiber or applying twist stress to the outside of the optical fiber.

In addition, it is possible to implement a PMD reduction device that can easily select and control various operation modes at a lower cost and simplicity.

Claims (22)

delete As a method of improving the polarization mode dispersion of an optical fiber, With respect to the spiral optical fiber which runs along the edge of the optical fiber base material, at least one heat source is arranged in the circumferential direction of the spiral fiber, and the heat source is rotated in the circumferential direction, thereby causing uneven heat in the circumferential direction of the spiral fiber. Applying; And Cooling the fluorescence fiber is applied non-uniform heat in the circumferential direction; including, Polarization mode dispersion of the optical fiber, characterized in that the polarization mode dispersion of the finished optical fiber is improved by changing the internal structure of the optical fiber in the cooling step by the circumferential temperature gradient of the optical fiber formed by the non-uniform heating in the circumferential direction How to improve. The method of claim 2, And at least one heat source is rotated periodically or aperiodically in the circumferential direction. The method of claim 2 or 3, And said at least one heat source is rotated in one direction or in one direction and in a direction opposite to this direction. The method of claim 2 or 3, The at least one heat source in addition to the circumferential rotation, the polarization mode dispersion improvement method of the optical fiber, characterized in that for moving forward and backward in the radial direction of the fiber. As a method of improving the polarization mode dispersion of an optical fiber, With respect to the spiral optical fiber which is lined up from the optical fiber base material, a plurality of heat sources are arranged in the circumferential direction of the spiral fiber, and the plurality of heat sources are operated sequentially or non-sequentially, thereby making it uneven in the circumferential direction of the spiral fiber. Applying heat; And Cooling the fluorescence fiber is applied non-uniform heat in the circumferential direction; including, Polarization mode dispersion of the optical fiber, characterized in that the polarization mode dispersion of the finished optical fiber is improved by changing the internal structure of the optical fiber in the cooling step by the circumferential temperature gradient of the optical fiber formed by the non-uniform heating in the circumferential direction How to improve. The method of claim 6, And the plurality of heat sources are sequentially operated in one direction or one direction and a direction opposite to the one direction along the circumferential direction. The method according to claim 6 or 7, The plurality of heat sources are the polarization mode dispersion improvement method of the optical fiber, characterized in that for moving forward and backward in the radial direction of the fiber. As a method of improving the polarization mode dispersion of an optical fiber, A circumferential circumference of the helical fiber is obtained by arranging a plurality of heat sources in the circumferential direction of the helical fiber, and reciprocating the plural heat sources in the tangential direction of the helical fiber with respect to the helical optical fiber which is drawn from the optical fiber base material. Applying non-uniform heat in the direction; And Cooling the fluorescence fiber is applied non-uniform heat in the circumferential direction; including, Polarization mode dispersion of the optical fiber, characterized in that the polarization mode dispersion of the finished optical fiber is improved by changing the internal structure of the optical fiber in the cooling step by the circumferential temperature gradient of the optical fiber formed by the non-uniform heating in the circumferential direction How to improve. The method according to claim 6 or 9, The plurality of heat sources are disposed along the circumferential direction, but also disposed along the advancing direction of the filamentous fiber, and arranged spirally with respect to the filamentary fiber. The method according to claim 2, 6 or 9, The heat source is a polarization mode dispersion improvement method of the optical fiber, characterized in that consisting of a heating element radiating heat rays of 600nm or more. Means for cutting the optical fiber base material to form bare fiber; At least one heat source rotatably disposed in the circumferential direction of the spiral fiber to form a non-uniform temperature gradient in the circumferential direction by applying uneven heat in the circumferential direction; Control means for controlling power and rotational speed and / or direction of the at least one heat source; Means for cooling the filamentous fiber in which the non-uniform temperature gradient is formed in the circumferential direction; Means for coating at least one coating layer around the cooled spliced fiber; Capstan for controlling the cutting speed of the optical fiber; And It includes; winding bobbin for winding the optical fiber passed through the capstan to the bobbin, And said control means rotates said at least one heat source periodically or aperiodically in said circumferential direction. delete The method of claim 12, And said control means rotates said at least one heat source in one direction or in one direction and in a direction opposite to said one direction. The method of claim 12, The at least one heat source is disposed rotatably in the circumferential direction, and is arranged to be retractable in the radial direction of the filamentary fiber, And said control means advances said at least one heat source periodically or aperiodically in a radial direction of said helical fiber. The method of claim 12, The heat source is an optical fiber manufacturing apparatus, characterized in that consisting of a heating element radiating a heat ray with a wavelength of 600nm or more. delete Means for cutting the optical fiber base material to form bare fiber; A plurality of heat sources arranged in the circumferential direction of the filamentous fiber to form a non-uniform temperature gradient in the circumferential direction by applying uneven heat in the circumferential direction; Control means for controlling the operation of the plurality of heat sources; Means for cooling the filamentous fiber in which the non-uniform temperature gradient is formed in the circumferential direction; Means for coating at least one coating layer around the cooled spliced fiber; Capstan for controlling the cutting speed of the optical fiber; And It includes; winding bobbin for winding the optical fiber passed through the capstan to the bobbin, And said control means operates said plurality of heat sources sequentially or non-sequentially in one direction or one direction and a direction opposite to said one direction along said circumferential direction. The method of claim 18, The plurality of heat sources are arranged to be retractable in the radial direction of the gliding fiber, And said control means advances said plurality of heat sources periodically or aperiodically in the radial direction of said filamentous fiber. Means for cutting the optical fiber base material to form bare fiber; A plurality of heat sources arranged in the circumferential direction of the filamentous fiber to form a non-uniform temperature gradient in the circumferential direction by applying uneven heat in the circumferential direction; Control means for controlling the operation of the plurality of heat sources; Means for cooling the filamentous fiber in which the non-uniform temperature gradient is formed in the circumferential direction; Means for coating at least one coating layer around the cooled spliced fiber; Capstan for controlling the cutting speed of the optical fiber; And It includes; winding bobbin for winding the optical fiber passed through the capstan to the bobbin, The plurality of heat sources are arranged to reciprocate in the tangential direction of the filamentary fiber, And said control means reciprocates said plurality of heat sources periodically or aperiodically in a tangential direction of said helical fiber. The method of claim 18 or 20, The plurality of heat sources are arranged along the circumferential direction, but also arranged along the advancing direction of the filamentary fiber, characterized in that arranged in a spiral with respect to the filamentary fiber. The method of claim 18 or 20, The heat source is an optical fiber manufacturing apparatus, characterized in that consisting of a heating element radiating a heat ray with a wavelength of 600nm or more.

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