JP3243002B2 - Optical coupler manufacturing method and manufacturing apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing an optical coupler used for optical communication, optical measurement, etc., and more particularly to a method for manufacturing two optical fibers by a melt drawing method. The present invention relates to a method for manufacturing a stretchable optical coupler and a manufacturing apparatus therefor.

[0002]

2. Description of the Related Art Optical couplers are widely used for optical communication, optical measurement, and the like. These optical couplers are generally manufactured by a melt drawing method using an optical fiber. In carrying out the melt drawing method, it is necessary to bring the coating removal portions of two optical fibers installed in parallel into contact with each other.

Conventionally, a method of contacting the stripped portions of two optical fibers with each other is disclosed in JP-A-60-13.
As disclosed in Japanese Patent No. 4208, two optical fibers arranged in parallel, two positions separated by a predetermined distance are fixedly clamped by blocks, respectively, and the optical fiber fixed to one of the blocks By releasing and twisting the optical fiber to knit it and fixing it to the block again,
There is a method in which the coating removal portions of two optical fibers are brought into contact with each other.

[0004]

According to the above-mentioned contact method, the coating removal portions of the two optical fibers can be brought into extremely effective contact, and a melt-stretched optical coupler can be suitably manufactured. However, this method
It is necessary to adjust the twist position of the optical fiber and control the tension of the optical fiber so that a certain amount of tension is not applied to the optical fiber during the twisting operation. It is extremely difficult at present to automate such tension management, and manual tension management is inevitable.

Further, when an optical coupler using a polarization-maintaining fiber is manufactured by a melt drawing method, it is necessary that the optical fiber be contacted in parallel without being twisted. Can not.

[0006] For this purpose, in this case, while observing with a microscope, a method is used in which the coating removal portions of the two optical fibers are manually pressed and brought into contact with each other, or described in, for example, US Patent No. 4,632,513. As described above, there is a method in which both sides of the stripped portion of the two optical fibers are manually contacted with each other by tying them with a cord or the like.Either method is used for contact work depending on the skill of the worker. There has been a problem that variations occur, and therefore, the excess loss of the manufactured optical coupler becomes large and the quality becomes unstable.

Accordingly, it is an object of the present invention to provide a manufacturing method capable of automating the operation of contacting an optical fiber, thereby saving labor, and producing a melt-stretched optical coupler of constant quality with good reproducibility. An object of the present invention is to provide a method and a manufacturing apparatus therefor.

[0008]

The above objects can be attained by an optical coupler manufacturing method and apparatus according to the present invention. In summary, the present invention, by holding the coating removal portion of two optical fibers installed in parallel at two positions separated by a predetermined distance, twisting the holding portion in the opposite direction to each other,
A portion in contact with each other is formed in the coating removal portion of the two optical fibers, and in this state, the contact portion is melted by heating, and the torsion is released when the contact portion is integrated by the melting. And put the two optical fibers back,
And it is an optical coupler manufacturing method characterized by performing melt drawing.

In the method of manufacturing such an optical coupler, a base and a base are rotatably supported on the base via a support, and are formed at a predetermined distance from each other, and are formed in respective radial directions. First and second rotary holders having grooves,
A twist head fixed to the rotary holder, the slit having a slit formed in alignment with a groove formed in the rotary holder, for holding a coating removal portion of two optical fibers installed in parallel; And a driving unit for rotating the first and second holders in an arbitrary direction at a maximum of 180 °.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method and an apparatus for manufacturing an optical coupler according to the present invention will be described in more detail with reference to the drawings.

FIGS. 1 and 2 show an embodiment of a manufacturing apparatus capable of suitably implementing the method for manufacturing an optical coupler according to the present invention. The optical coupler manufacturing apparatus 1 of the present embodiment has first and second rotary holders 2a and 2b which are arranged at a predetermined distance from each other. The first and second rotary holders 2
a and 2b have the same shape and configuration, and in this embodiment, are gears formed of a metal material such as SUS304, for example. Cylindrical flange portions 4a, 4b are formed on the side surfaces of the rotary holders 2a, 2b, respectively. The flange portions 4a, 4b are rotated by support bases 8a, 8b having cylindrical bearing portions 6a, 6b. It is freely held. The supports 8a and 8b are well known to those skilled in the art.
A Y-table or a horizontal moving means (not shown) such as a one-way slider is fixed to a base 10 which is reciprocally movable in a direction indicated by an arrow in FIG.

Further, grooves 12a and 12b having a width (W) in the radial direction are formed in the rotary holders 2a and 2b. The closed ends of the grooves 12a and 12b are formed so as to extend to the extent exceeding the rotation center O. Flanges 4a, 4b
A notch having a width (W) is formed in each of the bearings 6a and 6b so as to be aligned with the groove.

Further, on the side surface of the rotary holders 2a, 2b opposite to the side surface on which the cylindrical flange portions 4a, 4b are formed, in the present embodiment, for example, the thickness (t) is set to 1 mm. For example, rectangular twist heads 14a and 14b formed of a metal material such as SUS304 are fixed. The twist heads 14a, 14b are also provided with slits 16a, 16b having a width (W ₀ <W) smaller than the width (W) of the grooves 12a, 12b in a manner to be aligned with the grooves 12a, 12b of the rotary holders 2a, 2b. It is formed. This slit 1
The closed ends of 6a, 16b are preferably located approximately at the center O of rotation of the rotary holders 2a, 2b.

Although not limited, usually, the diameter of the rotary holders 2a and 2b is 40 to 50 mm and the grooves 12a and 1b are
2b has a width W of 3 to 4 mm, and the twist heads 14a, 14
b of the slit 16a, 16b width W ₀ of 140 to 150
μm is preferred. Further, the distance between the first and second rotary holders 2a and 2b can be arbitrarily set within a range that does not disturb the temperature distribution of the optical fiber heated from the heating source during melt drawing. 18 mm.

According to the present embodiment, the first rotary holder 2a
, A rack 18a is provided so as to mesh with each other. The rack 18 a includes a support 20 fixed to the base 10.
It is movably supported by a. Also, this rack 1
8a, the output drive gear 22a of the motor Ma is meshed, and the rack 18a is driven in the direction of the arrow by urging the motor Ma, whereby the rotary holder 2a
Is rotated around its rotation center O. Although not shown in FIG. 1, a rack 18a is also engaged with the second rotary holder 2b, and the rack 18a is driven by a drive gear (not shown) driven by another motor (not shown) similar to the motor Ma. (Not shown), and by urging the motor, the rack 18b is driven in the direction of the arrow, whereby the rotary holder 2b is rotated around its rotation center O. By using a driving means such as a pulse motor as a motor as a driving means of the rotary holders 2a and 2b, the rotation angle of the rotary holder can be more accurately controlled. The first and second rotary holders 2a, 2b
It is preferable that each can be rotated in the range of 140 ° to 180 °. This will be further described later.

The optical coupler manufacturing apparatus 1 having the above configuration does not require the use of particularly high-precision element parts, and the mechanical accuracy may be of a normal grade.

Next, a manufacturing method of the present invention, which is performed using the manufacturing apparatus 1 having the above-described configuration, will be described with reference to FIGS.

As shown in FIG. 3, first, two optical fibers f, which are coated and removed by a predetermined length, usually about 25 mm, are placed on a commonly used melt drawing table (not shown). Install in parallel. At this time, the manufacturing apparatus 1
As shown by a dashed line in FIG.
The optical fiber f has been moved to a position farthest from the optical fiber on the melt drawing table, so that the rotary holders 2a and 2b and the twist heads 14a and 14b do not interfere with the installation of the optical fiber f on the melt drawing table. .

Next, the base 10 of the manufacturing apparatus 1 is moved toward the optical fiber f. Groove 1 of rotary holder 2a, 2b
The slits 16a, 16b of the twist heads 2a, 12b and the twist heads 14a, 14b are located at a horizontal position as shown in FIGS. 1 and 2, and the height from the base 10 is equal to the height of the melt drawing table. The height is set to coincide with the height position of the installed optical fiber f. Accordingly, as the base 10 is moved toward the optical fiber f, the optical fiber f passes through the grooves 12a, 12b of the rotary holders 2a, 2b and, as shown in FIGS. The optical fiber f is connected to the slit 16 of the twist heads 14a and 14b.
The movement of the base 10 is stopped when the base 10 comes into contact with the closed ends of the a and 16b. This state is shown in FIG.

Next, by energizing the motor Ma,
The first rotary holder 2a is rotated up to 180 ° in the first direction via the drive gear 22a and the rack 18a.
At the same time, by energizing a motor (not shown), the second rotating holder 2b is connected to the first direction of the first rotating holder 2a via the driving gear (not shown) and the rack 18b. In the opposite direction, rotate up to 180 °. As a result, the coating removal portions of the two optical fibers f are twisted in opposite directions while being held by the twist heads 14a and 14b. First and second rotating holders 2a, 2
When b rotates in the opposite direction by about 140 ° or more, the coating removal portions of the two optical fibers f start to contact each other, and FIG.
As shown in (1), an optical fiber contact portion is formed at a central portion between the first and second rotary holders 2a and 2b. When the rotation of each of the rotary holders 2a and 2b is smaller than 140 °, for example, when the rotation is about 100 °, contact between the coating removal portions of the two optical fibers f does not occur. If the rotation angle exceeds 180 °, the tension applied to the optical fiber f will increase significantly, and the excess loss of the manufactured optical coupler will be 0.4 dB.
It is not preferable because it is above.

According to the present invention, the twist head 14a,
As shown in FIG. 2, the slit width (W ₀ ) of 14b is about 10 to 20% larger than the diameter of the clad of the optical fiber f, and when the optical fiber f having a normal clad diameter of 125 μm is used. Is preferably 150 μm. The inner surfaces of the slits 16a and 16b are preferably mirror-finished. Therefore, when the first and second rotary holders 2a and 2b rotate in opposite directions to each other and the optical fiber f is twisted by being sandwiched by the twist heads 14a and 14b, the optical fiber f is divided into the slits 16a and
The optical fiber can move freely in the axial direction within 16b, so that an excessive tension is not applied to the optical fiber.
Further, it is possible to prevent the optical fiber f from being damaged by the twist caused by the rotary holder.

While maintaining the manufacturing apparatus 1 in the state shown in FIG.
The optical fiber contact portion is heated by a heating source (not shown) to a temperature sufficient to melt the optical fiber, for example, 1600 ° C., and this state is maintained for a predetermined time, for example, about 30 seconds to 1 minute. At this time, the optical fiber f may be stretched by applying a slight tension, if necessary.

As a result, the viscosity of the quartz glass forming the core of the optical fiber f decreases, and the two optical fibers f move in the direction in which they contact each other due to the surface tension of the quartz glass. f is completely integrated.

According to the present invention, at this time, the first and second rotary holders 2a and 2b are respectively rotated in the directions opposite to the conventional ones, and returned to the original position, that is, the position shown in FIG. And the twist of the optical fiber f is released. At this time, the two integrated optical fibers f do not separate.

Next, the melt drawing stage is driven to pull the optical fiber f in both axial directions to perform the melt drawing. The stretching speed is 13 to 100 μm / sec, for example, 25 μm / sec. This reduces the outer diameter of the optical fiber,
An optical coupler is formed. When a predetermined light branching ratio is obtained, the stretching is stopped, and the heating source is removed.

Thereafter, the manufacturing apparatus 1 is connected to the optical fiber f.
Moving away from the twist head 14a,
14b and the rotary holders 2a and 2b are extracted from the optical fiber f. In this state, the optical fiber f is fixed to the glass substrate with a resin. After the resin coupler is completed, the optical coupler is removed from the melt drawing table, and a new optical fiber is set on the melt drawing table in order to manufacture the next optical coupler.

The excess loss of the optical coupler manufactured as described above could be reduced to 0.2 dB or less. The temperature characteristics were also good, and the branching ratio variation was within ± 2% in the range of + 40 ° C. to −20 ° C.

[0028]

As described above, in the optical coupler manufacturing method according to the present invention, the stripped portions of two optical fibers installed in parallel are brought into contact with each other by twisting in opposite directions. This contact portion is heated to start the melt drawing, the twist is released in the middle of the melt drawing, the two optical fibers are returned, and the melt drawing is further performed. This makes it possible to automate the contact work, thereby saving labor and, moreover, making it possible to produce a melt-stretched optical coupler of constant quality with good reproducibility. Further, the optical coupler manufacturing apparatus of the present invention does not require the use of particularly high-precision element parts, and has the advantage that the mechanical accuracy may be of a normal grade.

[Brief description of the drawings]

FIG. 1 is a perspective view of one embodiment of an optical coupler manufacturing apparatus according to the present invention.

FIG. 2 is a front view showing a rotary holder and a twist head.

FIG. 3 is an explanatory diagram for explaining the manufacturing method of the present invention;
4 shows a relationship between an optical fiber, a rotary holder, and a twist head.

FIG. 4 is an explanatory diagram for explaining the manufacturing method of the present invention;
FIG. 4 shows a state in which the optical fiber is twisted, and shows a relationship between the optical fiber and the rotating holder and the twist head at this time.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical coupler manufacturing apparatus 2a, 2b Rotary holder 10 Base 12a, 12b Groove 14a, 14b Twist head 16a, 16b Slit 18a, 18b Rack

Claims (2)

(57) [Claims] 1. A coating removal portion of two optical fibers installed in parallel is sandwiched between two positions separated by a predetermined distance,
By twisting the holding portions in opposite directions, a portion that is in contact with each other is formed at the coating removal portion of the two optical fibers, and in this state, the contact portion is melted by heating, and the contact is caused by the melting. A method for producing an optical coupler, comprising: releasing the twist when the parts are integrated, returning the two optical fibers to their original state, and performing melt drawing. 2. A first base having a radially formed groove rotatably supported on the base via a support base and spaced apart from each other by a predetermined distance.
And a second rotary holder, and a slit formed in alignment with a groove formed in the rotary holder to sandwich the coating removal portions of two optical fibers installed in parallel,
And a twist head fixed to the rotating holder;
The first and second holders can be moved up to 180 ° in any direction.
An optical coupler manufacturing apparatus, comprising: a driving unit for rotating.