JPH05264863A - Terminal part of optical fiber - Google Patents

Abstract

PURPOSE:To enable production at a high yield under less strict production conditions without requiring adhering and fixing between an optical fiber and a ferrule by inserting a glass pipe fixed to the outer peripheral surface of the optical fiber between a capillary and an internally fitting pipe and fixing its position. CONSTITUTION:The terminal part of the optical fiber is constituted by previously putting the glass pipe 14 on the optical fiber 1 to integrally fix the pipe and the fiber, then inserting the optical fiber 1 into the ferrule 11 and inserting the end face 1A of the optical fiber 1 into the capillary 12. The terminal part is completed if the internally fitting pipe 13 is fixed to the inside surface of the ferrule 11 after the above-mentioned insertion. The internally fitting pipe 13 is disposed in such position where the pipe holds the glass pipe 14 together with the capillary 12 to prevent the glass pipe 14 from moving. Such assembly operation is easier than in the connection of ordinary optical fibers and the production conditions thereof are less strict. The increasing of the yield to 100% is possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber terminal section having improved heat resistance for a terminal section in which a glass optical fiber is housed in a ferrule made of metal or the like.

[0002]

2. Description of the Related Art Optical fibers are composed of multi-component glass, quartz, plastic, or the like. When used at relatively high temperatures, glass fibers other than plastic are used. In order to arrange an optical element on the end face of the optical fiber and input and output an optical signal, an optical fiber terminal portion as shown in FIG. 2 is formed, for example. In the figure, an optical fiber 1 is a shaft hole 2A of a cylindrical ferrule 2.
And is supported at one end of the shaft hole 2A via a capillary 3. In this state, the end face 1A of the optical fiber 1
Are polished together with the capillaries 3 and arranged so as to face optical elements such as a light emitting element and a light receiving element.

On the other hand, an outer pipe 4 made of stainless steel or the like is adhesively fixed to the inner surface of the ferrule 2.
Further, an inner pipe 5 made of similar stainless steel or the like is adhesively fixed to the outer peripheral surface of the optical fiber 1. Then, the adhesive 6 is poured into the space formed between the outer pipe 4 and the inner pipe 5, so that the optical fiber 1 is fixed to the axial hole of the ferrule 2 via the outer pipe 4 and the inner pipe 5. I have to.

[0004]

By the way, the optical fiber terminal portion having the above-mentioned structure is used for laser output, for example, and is required to have a performance capable of being used stably even at a temperature of about 400 degrees Celsius. .. However,
The ferrule 2 is made of metal such as brass,
The capillary 3 is made of ceramic or the like. Since the optical fiber 1 is made of glass, there is a large difference in coefficient of linear expansion between the ferrule 2 and the optical fiber 1. Therefore, under a high temperature atmosphere, a force that causes a displacement in the longitudinal direction is applied between the optical fiber 1 and the ferrule 2, the adhesive 6 is peeled off, and the optical fiber 1 falls off from the ferrule 2 or End face 1A of fiber 1
However, there is a problem in that the object pops out in front of the capillary 3.

In order to solve this, the above-mentioned outer pipe 4
The clearance between the inner pipe 5 and the inner pipe 5 is optimally set, and a test for whether or not it can withstand a predetermined tensile tension is performed in an atmosphere of 450 ° C., for example, and a good product and a defective product are selected. However, in such a conventional method, there is a problem that the yield is deteriorated and the product cost is increased. In order to solve the above problems, the adhesive for adhering the outer pipe 4 and the inner pipe 5 has a coefficient of linear expansion which is between that of metal and glass, and the behavior of metal and glass at high temperature. To act as a buffer to absorb the difference in the expansion rate, and
It is necessary to have the property of not thermally decomposing even at high temperatures. However, none of the adhesives on the market satisfy all such conditions.

Further, a method of directly and mechanically integrally fixing the ferrule 2 and the optical fiber 1 together can be considered. However, this method may cause a significant decrease in fiber strength. The present invention has been made in view of the above points, and it is an object of the present invention to provide an optical fiber connection portion that maintains sufficient mechanical characteristics even under a high temperature atmosphere, has a gentle manufacturing condition, and has a good yield. It is intended.

[0007]

An optical fiber connecting portion of the present invention comprises a ferrule, an optical fiber supported at one end of an axial hole of the ferrule via a capillary and having an end face exposed, and the other end of the ferrule. An internal pipe fixed to the inner surface on the side and arranged in a cylindrical space surrounding the optical fiber in the axial hole of the ferrule, and arranged in the cylindrical space between the internal pipe and the capillary, the optical fiber It is characterized by comprising a glass pipe fixed to the outer peripheral surface.

[0008]

In this connecting portion, the glass pipe fixed to the outer peripheral surface of the optical fiber is sandwiched between the capillary and the internal pipe to fix its position. The crow pipe and the ferrule do not have to be fixed using an adhesive or the like. As a result, no stress is applied between the ferrule and the optical fiber due to the difference in linear expansion coefficient between the ferrule and the optical fiber. Further, it is easy to manufacture without using an adhesive or the like.

[0009]

The present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 1 is a vertical cross-sectional view showing an embodiment of an optical fiber connecting portion of the present invention. In the figure, the left end of the optical fiber 1 is
It is supported by a ferrule 11 made of stainless steel via a capillary 12. An end surface 1A of the optical fiber 1 is exposed on an end surface on the left side of the capillary 12 shown in the drawing, and faces an unillustrated laser light source or the like. An internal pipe 13 made of stainless steel is inserted into the shaft hole 11A on the right side of the ferrule 11 in the drawing. in this case,
The internal pipe 13 has a shaft hole 11A of the ferrule 11.
It is arranged so as to leave a cylindrical space having a constant length L inside. Then, in this cylindrical space, a glass pipe 14 fixed in advance to the outer peripheral surface of the optical fiber 1 is arranged.

That is, in the optical fiber 1, the primary coat, which is the coating material coated on the outer peripheral surface of the optical fiber 1 in advance, is removed, leaving a portion to be inserted into the capillary 12, and heating a glass pipe having a length of, for example, about 10 mm. While covering integrally. In this case, this glass pipe 14
The optical fiber 1 and the optical fiber 1 are integrated by heat fusion. On the other hand, the space between the internal pipe 13 and the ferrule 11 may be fixed with an adhesive, or the size may be appropriately selected and mechanically fixed by fitting or the like without using an adhesive. Is. It should be noted that the optical fiber terminal section configured as described above includes the internal pipe 13 and the optical fiber 1.
Although a certain amount of space is left between the ferrule 11 and the glass pipe 14, the glass pipe 14 is sandwiched between the capillary 12 and the internal pipe 13, but is not fixed to the ferrule 11 with an adhesive.

In the optical fiber end portion of the present invention having the above-mentioned configuration, the glass pipe 14 is previously covered with the optical fiber 1 and integrally fixed, and then the optical fiber 1 is inserted into the ferrule 11 to form the end face 1A of the optical fiber 1. Is inserted into the capillary 12. Then, the internal pipe 13 is fixed to the inner surface of the ferrule 11 to complete the process. In this case, the internal pipe 1
The reference numeral 3 holds the glass pipe 14 together with the capillary 12 and is arranged at a position where the glass pipe 14 does not move.

The above assembling work is easier than the conventional optical fiber connecting portion. Moreover, the manufacturing conditions thereof are more relaxed than in the past, and the yield can be 100%. Further, since the glass pipe 14 fixed to the outer circumference of the optical fiber 1 has the same linear expansion coefficient as that of the optical fiber 1, there is no deviation between the two even when the temperature becomes high. on the other hand,
The glass pipe 14 is a capillary 12 and an internal pipe 13
Since the glass pipe 14 does not move, the end face 1A of the optical fiber 1 does not move because it is sandwiched between
There is no danger of sticking out from 2. Therefore, 400 ° C
It is possible to maintain sufficient reliability even at a high temperature.

[0013]

As described above, since the optical fiber terminal portion of the present invention does not require adhesive fixation between the optical fiber and the ferrule, it can be manufactured with low production conditions and high yield. Furthermore, since no stress is applied between the two in a high-temperature atmosphere and the optical fiber is fixed by the glass pipe, it has sufficient strength against pulling force, and its end face is projected from the capillary. Still not.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of an optical fiber connecting portion of the present invention.

FIG. 2 is a vertical cross-sectional view of a conventional optical fiber connecting portion.

[Explanation of symbols]

 1 Optical Fiber 1A End Face of Optical Fiber 11 Ferrule 12 Capillary 13 Internal Pipe 14 Glass Pipe

Claims (1)

[Claims] 1. A ferrule, an optical fiber which is supported at one end of a shaft hole of the ferrule via a capillary and has an end face exposed, and a ferrule fixed to the inner surface on the other end side of the ferrule. An internal pipe arranged in a cylindrical space surrounding the optical fiber, and a glass pipe arranged in the cylindrical space between the internal pipe and the capillary and fixed to the outer peripheral surface of the optical fiber. An optical fiber terminal section characterized by the above.