JP2004347946A - Manufacture device and manufacture method of optical fiber coupler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide manufacture device of optical fiber coupler capable of preventing the enlargement of size of an optical fiber coupler. <P>SOLUTION: A fiber holding means holds one piece of optical fiber or holds plural pieces of optical fibers in such a manner that clads of the optical fibers come into contact with one another and the held optical fibers are elongated. First and second burners heat the optical fibers held by the fiber holding means. The second burner forms a flame finer than the flame formed by the first burner. A moving mechanism controls the attitudes of the first burner and the second burner in such a manner that either of the state that the flame formed by the first burner heats the optical fiber held by the fiber holding means and the state that the flame formed by the second burner heats the optical fiber held by the fiber holding means is brought about. The moving mechanism moves the second burner in the length direction of the optical fiber held by the fiber holding means. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical fiber coupler manufacturing apparatus and a manufacturing method, and in particular, an optical fiber coupler manufacturing apparatus and a manufacturing method in which one optical fiber is drawn in advance, and the drawn optical fiber and another optical fiber are fused. About.
[0002]
[Prior art]
In a wavelength division multiplexing (WDM) optical communication system, development of an optical fiber coupler with small wavelength dependence is expected. Non-Patent Document 1 discloses that one of two optical fibers is pre-drawn and thinned, and that the pre-drawn optical fiber and another optical fiber are fused to each other so as to have a small wavelength dependency. A theoretical consideration has been made on a two-branch optical fiber coupler.
[0003]
FIG. 3A is a plan view of two optical fibers in a state where fusion is performed. Part of the cladding 1C of the optical fiber 1 is exposed, and part of the cladding 2C of the optical fiber 2 is exposed. The optical fiber 2 is pre-drawn, a part of the exposed cladding 2C is thinned, and the thin part 4 has a substantially uniform thickness. A pair of fiber clamps 5 and 6 hold the exposed claddings 1C and 2C such that their side surfaces are in contact with each other. When the clad 2C is fixed at a point inside both ends of the portion 4 having a uniform thickness of the clad 2C, the side surfaces of the two clads 1C and 2C can be brought into contact.
[0004]
The portion 3 inside the position fixed by the pair of fiber clamps 5 and 6 is heated by a burner to fuse the claddings 1C and 2C.
[0005]
[Non-patent document 1]
K. OKAMOTO, Theoretical Investigation of Light Coupling Phenomena in Wavelength-Flattened Couplers, "Journal of Lightwave Technology." 8 No. 5, May 1990, p. 678-683
[0006]
[Problems to be solved by the invention]
A liquefied petroleum gas (LPG) burner, a hydrogen burner, or the like is used at the time of pre-drawing and fusing the optical fiber. Since backfire occurs when the tip of the LPG burner is made thicker, the thickness of the tip is set to about 1 mm. For this reason, the thickness of the flame formed by the LPG burner is at most about 4 mm. Due to the small size of the flame, the flame must be reciprocated along the length of the optical fiber in order to uniformly heat a long area when the optical fiber is fused.
[0007]
When the flame is reciprocated, the heating becomes excessive at the turning point of the flame (both ends of the heated portion), and the optical fiber may be locally thinned. When a thin portion is locally generated, an optical signal leaks therefrom, resulting in a large loss.
[0008]
When a hydrogen burner is used, a flame having a thickness of about 12 mm can be formed. When the thickness of the flame is about 12 mm, the optical fiber can be fused without moving the flame. However, in the method of performing the pre-stretching while fixing the hydrogen burner as in the case of the fusion, it is not possible to lengthen the thinned uniform portion.
[0009]
FIG. 3B shows a state where the clad 2C of the optical fiber 2 preliminarily stretched by fixing the hydrogen burner and the clad 1C of the optical fiber 1 not preliminarily stretched are held by the fiber clamps 5 and 6. FIG. Due to the short uniform thin portion 4, the fiber clamps 5 and 6 will hold the cladding 2C outside of both ends of the thin portion 4. Therefore, a gap is formed between the claddings 1C and 2C, and the claddings do not come into contact with each other. Even if heating is performed in this state, the claddings 1C and 2C cannot be fused.
[0010]
As shown in FIG. 3C, by moving the hydrogen burner 10 having the flame 11 reciprocated along the clad 2C of the optical fiber 2, a portion having a uniform thickness can be lengthened. The length of the uniform portion of the thickness is substantially equal to the amplitude d ₁ of the reciprocating movement of the hydrogen burner 10.
[0011]
A portion outside the both ends of the uniform thickness portion is exposed to the flame. Prior to the pre-stretching, the coating film that has been exposed to the flame must be removed. When the thickness of the flame 11 of the hydrogen burner 10 and d _2, stripping length length of the coating film will d _2/2 at the other. The length of the stripped fee will be d ₂ on both sides. If the thickness _{d 2} is 10mm of flame, it must ensure the stripping length of 10mm or more in total. This stripping margin increases the size of the optical fiber coupler.
[0012]
SUMMARY OF THE INVENTION An object of the present invention is to provide an optical fiber coupler manufacturing apparatus and a manufacturing method capable of preventing an increase in the size of an optical fiber coupler.
[0013]
[Means for Solving the Problems]
According to one aspect of the present invention, a fiber that holds one optical fiber or holds a plurality of optical fibers so that claddings of the optical fibers are in contact with each other, and can stretch the held optical fiber. Holding means, a first burner for heating the optical fiber held by the fiber holding means, and a flame formed by the first burner for heating the optical fiber held by the fiber holding means. An optical fiber coupler manufacturing apparatus is provided which has a second burner for forming a thin flame, and a moving mechanism for moving the second burner in a length direction of the optical fiber held by the fiber holding means. You.
[0014]
With this manufacturing apparatus, the following manufacturing method can be performed.
[0015]
According to another aspect of the present invention, (a) a flame is formed with a burner, the first optical fiber is heated while moving the flame in the longitudinal direction of the first optical fiber, and the heated portion is heated. (B) bringing the side surface of the drawn portion of the first optical fiber into contact with the side surface of at least one second optical fiber, and The portion where the first optical fiber and the second optical fiber are in contact with each other is heated with a thick flame, and the heated portion is stretched to fuse the first optical fiber and the second optical fiber. And a step of producing the optical fiber coupler.
[0016]
Since the thin flame is moved in the longitudinal direction at the time of the pre-stretching, it is possible to reduce the amount of stripping of the coating to be provided at both ends of the portion to be heated.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
1A and 1B are plan views of a main part of an optical fiber coupler manufacturing apparatus according to an embodiment. FIG. 1A shows a state in which one optical fiber 35 is predrawn, and FIG. 1B shows a state in which two optical fibers 35 and 38 are fused.
[0018]
As shown in FIG. 1A, a part of the coating film of the optical fiber 35 to be predrawn is peeled off, and the clad 35C is exposed. The fiber clamps 30 and 31 support the optical fiber 35 slightly inside both ends of the exposed clad 35C.
[0019]
The support member 24 is supported by the linear guide 25 so as to be movable in a direction parallel to the length direction of the optical fiber 35 held by the fiber clamps 30 and 31. The arms 22 and 23 are attached to the support member 24. The arms 22 and 23 can pivot around a pivot axis parallel to the length direction of the optical fiber 35. An LPG burner 20 and a hydrogen burner 21 are held at the tips of the arms 22 and 23, respectively.
[0020]
By moving the support member 24 along the linear guide 25, one of the LPG burner 20 and the hydrogen burner 21 can be disposed between the fiber clamps 30 and 31. FIG. 1A shows a state in which the LPG burner 20 is disposed between the fiber clamps 30 and 31.
[0021]
As shown in FIG. 1A, when the arm 22 is lowered, the tip of the LPG burner 20 is disposed slightly above the clad 35C fixed to the fiber clamps 30 and 31.
[0022]
FIG. 2A is a cross-sectional view of the vicinity of the tip of the LPG burner 20 in the state of FIG. The tip of the LPG burner 20 faces the side surface of the clad 35C. The clad 35C is heated by the flame 26 blown out from the tip of the LPG burner 20. The thickness of the flame 26 is about 4 mm.
[0023]
By reciprocating the support member 24 shown in FIG. 1A along the linear guide 25, a desired length portion of the clad 35C can be heated. The pre-drawing of the optical fiber 35 is performed while heating the exposed clad 35C. Since the thickness of the flame 26 is about 4 mm, the length of each of the stripping margins of the coating film to be secured on both sides of the thinned uniform thickness portion of the clad 35C may be about 2 mm.
[0024]
As shown in FIG. 1B, the pre-stretched optical fiber 35 and the non-pre-stretched optical fiber 38 are combined with a narrow clad 35C of the optical fiber 35 and an exposed clad 38C of the optical fiber 38. Are held by the fiber clamps 30 and 31 so that the side surfaces thereof contact each other.
[0025]
At this time, the fiber clamps 30 and 31 come into contact with the portion where the clad 35C is stretched and made uniform in thickness in the step shown in FIG. The distance between the fiber clamps 30 and 31 is smaller than the distance between the fiber clamps 30 and 31 during the pre-stretching shown in FIG. Since the fiber clamps 30 and 31 come into contact with the portions of the clad 35C having a uniform thickness, the side surfaces of the clads 35C and 38C can be easily brought into contact with each other.
[0026]
The support member 24 is moved along the linear guide 25, and the hydrogen burner 21 is disposed between the fiber clamps 30 and 31. The arm 23 is lowered, and the tip of the hydrogen burner 21 faces the mutually contacted portions of the clads 35C and 38C held by the fiber clamps 30 and 31.
[0027]
FIG. 2B is a sectional view of the hydrogen burner 21. At the tip of the hydrogen burner 21, a columnar cavity 21b whose lower end is open and whose upper end is closed is defined. The diameter of the cavity 21b is about 12 mm. A hydrogen gas flow path 21a is opened on the upper surface of the cavity 21b. Hydrogen gas is supplied from the hydrogen gas passage 21a into the cavity 21b, and a flame 27 blows out from the lower end of the cavity 21b. The diameter of the flame 27 amounts to about 12 mm. The claddings 35C and 38C pass through the interior of the flame 27.
[0028]
Returning to FIG. 1B, the description will be continued. The optical fibers 35 and 38 are drawn without moving the position of the hydrogen burner 21. Thereby, the claddings 35C and 38C can be fused. Since the hydrogen burner 21 is not moved, excessive heating of the turn-back position that occurs when the hydrogen burner 21 is moved back and forth does not occur. For this reason, the cladding can be prevented from being locally thinned, and an increase in loss can be prevented.
[0029]
During pre-stretching, the clad is heated while reciprocating a burner that forms a thin flame, so that the stripping amount of the coating of the optical fiber can be reduced as compared with a case where a burner that forms a thick flame is reciprocated. This makes it possible to reduce the size of the optical fiber coupler.
[0030]
In the above embodiment, an LPG burner is used for pre-drawing one optical fiber, and a hydrogen burner is used for fusing two optical fibers. However, other burners may be used. At this time, when the flame formed by the burner used at the time of fusion is thicker than the flame formed by the burner used at the time of pre-stretching, the same effect as that of the first embodiment is expected. . At the time of pre-stretching, it is preferable to use a burner which forms a flame having a thickness of 3 to 6 mm, and at the time of fusion, it is preferable to use a burner which forms a flame having a thickness of 7 to 15 mm.
[0031]
Further, in the above embodiment, a two-branch optical fiber coupler is manufactured by fusing two optical fibers, but a multi-branch optical fiber coupler is manufactured using three or more optical fibers. The method according to the above embodiment can be applied. When three or more optical fibers are to be fused, one optical fiber is pre-drawn while a burner with a thin flame is used and the burner is reciprocated. The pre-drawn optical fiber and two or more non-pre-drawn optical fibers are fused by using a burner with a thick flame and fixing the burner. Preferably, the plurality of optical fibers that have not been pre-drawn are arranged at substantially equal intervals around the optical fiber that has been pre-drawn.
[0032]
Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. For example, it will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.
[0033]
【The invention's effect】
As described above, according to the present invention, during pre-drawing of an optical fiber, a flame smaller than the flame used at the time of fusion is used, and the flame is reciprocated. It is possible to shorten the stripping allowance of the covering film. This makes it possible to reduce the size of the optical fiber coupler.
[Brief description of the drawings]
FIG. 1 is a plan view of an optical fiber coupler manufacturing apparatus according to an embodiment.
FIG. 2 is a cross-sectional view near the tips of an LPG burner and a hydrogen burner.
FIGS. 3A and 3B are a plan view of a portion where two optical fibers are to be fused and a diagram showing a state of reciprocation of a burner in a pre-stretching step. FIGS.
[Explanation of symbols]
1, 2 Optical fiber 1C, 2C Cladding 3 Heated portion 4 Uniform thickness 5, 6 Fiber clamp 10 Hydrogen burner 11 Flame 20 LPG burner 21 Hydrogen burner 22, 23 Arm 24 Support member 25 Linear guide 26, 27 Flame 30 , 31 Fiber clamp 35, 38 Optical fiber 35C, 38C Cladding

Claims (4)

Fiber holding means for holding one optical fiber, or holding a plurality of optical fibers so that claddings of the optical fibers are in contact with each other, and extending the held optical fiber;
A first burner for heating the optical fiber held by the fiber holding means,
A second burner for heating the optical fiber held by the fiber holding means and forming a flame smaller than the flame formed by the first burner;
A moving mechanism for moving the second burner in the longitudinal direction of the optical fiber held by the fiber holding means. Further, a state in which the flame formed by the first burner heats the optical fiber held by the fiber holding means, and a state in which the flame formed by the second burner is held by the fiber holding means. 2. The optical fiber coupler manufacturing apparatus according to claim 1, further comprising a burner driving mechanism that controls a posture of the first burner and the second burner so as to be in a state of heating the optical fiber. 3. . (A) forming a flame with a burner, heating the first optical fiber while moving the flame in the longitudinal direction of the first optical fiber, and stretching the heated portion;
(B) bringing the side face of the drawn portion of the first optical fiber into contact with the side face of at least one second optical fiber, and using a flame larger than the flame used in the step (a), Heating the contacted portion between the first optical fiber and the second optical fiber, stretching the heated portion, and fusing the first optical fiber and the second optical fiber. Optical fiber coupler manufacturing method. 4. The method according to claim 3, wherein in the step (b), heating is performed on a portion in contact with the first optical fiber and the second optical fiber without relatively moving a flame for heating. Optical fiber coupler manufacturing method.

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