JP2002139633A - Optical fiber fixture and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve tensile strength in order to prevent an optical fiber from breaking from an optical fiber fixture. SOLUTION: In the optical fiber fixture, wherein the optical fiber 1 the coating at the tip end part of which is removed is inserted into an inner hole 2a of a ferrule 2 and is fixed by soldering at the tip end part of the ferrule 2, and also an adhesive 13 is filled into the tail end part of the inner hole 2a of the ferrule 2, the adhesive-filling part of the inner hole 2a of the ferrule 2 is formed so as to be widened toward the tail end, a gap y between the inner hole 2a and the optical fiber 1 at the tail end of the ferrule 2 is set at >=0.15 mm, and moreover length x of the part, where the coating removed part 1b of the optical fiber 1 is stuck by the adhesive 13, is set at >=2 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber fixture for fixing an optical fiber used in optical communication and the like, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, an optical fiber fixing device for fixing an optical fiber used for optical signal processing such as optical communication has been used for a semiconductor laser module or the like. A hermetic sealing structure is also required to ensure reliability.

[0003] In a module incorporating an optical semiconductor element, as a method of coupling light emitted from the optical semiconductor element to an optical fiber, a lens coupling system using a lens or a spherical optical fiber coupling system in which the tip of an optical fiber is formed in a lens. Etc. are known.

Conventionally, in a hermetically sealed structure of an optical fiber fixing device, as shown in FIG. 6A, a coating removal portion 1b of an optical fiber 1 is inserted into a ferrule 2 and sealed with an adhesive 13.
Further, a cylindrical introduction portion 1 formed integrally with the package.
4, a ferrule 2 is fitted, and the coating removal portion 1b of the optical fiber 1 is hermetically sealed by bonding with a low-melting glass 15 or the like (see Japanese Patent Application Laid-Open No. 7-92335).

[0005] As shown in FIG. 6 (b), the optical fiber 1 bonded and joined in a state where it is aligned with the ferrule 2.
The metallized portion 1b may be fixed to the ferrule 2 with solder 5 in some cases.

[0006] Then, an adhesive is injected from an adhesive filling hole on the outer peripheral side surface of the ferrule 2 and gas is vented through an exhaust hole 4 (see Japanese Patent Application Laid-Open No. 2000-180660).

[0007]

However, according to the conventional optical fiber fixing device shown in FIG. 6A, the introduction portion 14 and the ferrule 2 are hermetically sealed with a low-melting glass 15 or the like, and the ferrule 2 is sealed. Although it is filled with the adhesive 13, there is a problem that hermetic sealing cannot be guaranteed by the ferrule 2 alone.

According to the conventional optical fiber fixing device shown in FIG. 6B, the filling hole 8 and the exhaust hole 4 are formed on the outer peripheral side surface of the ferrule.
However, such a filling method has a problem that since the filling hole 8 and the exhaust hole 4 are biased to one side, unevenness occurs in the stress distribution of the adhesive 13 and the strength is deteriorated.

Further, these structures have a problem that bubbles 11 as shown in FIG. 6D and liquid dripping 12 as shown in FIG. 6C are generated.

The air bubbles 11 are trapped when the adhesive 13 is filled in the ferrule 2 after joining with the low melting point glass 15 or the solder 5, which causes the adhesive strength of the adhesive 13 to deteriorate, and 1, the tensile strength of the coating removal portion 1b and the ferrule 2 is reduced.

In order to remove the air bubbles 11, it is necessary to vent the air by vacuum degassing. However, the adhesive 13 in the ferrule 2 generates the foam 10 due to the pressure difference, and the dripping 12 shown in FIG. There is a problem of causing.

There is a disadvantage that interference occurs when the ferrule 2 in which the dripping 12 occurs is fitted into the lead-in portion 14 of the package as shown in FIG.

In any case, since the filling area of the adhesive 13 is cylindrical, the adhesive 13 must be injected more than necessary, and bubbles are inevitably generated. The structure is not suitable for

[0014]

In view of the above, the present invention provides
The optical fiber with the coating on the distal end removed is inserted into the inner hole of the ferrule, and is solder-fixed at the distal end of the ferrule, and the rear end of the inner hole of the ferrule is filled with an adhesive. The adhesive-filled portion of the inner hole has a shape expanding toward the rear end, the gap between the inner hole and the optical fiber at the rear end of the ferrule is 0.15 mm or more, and the coating removed portion of the optical fiber is bonded with an adhesive. The length of the portion is 2 mm or more.

Further, according to the present invention, there is provided a guard for preventing the adhesive from dripping at the rear end of the ferrule after inserting the optical fiber from which the coating at the front end has been removed into the inner hole of the ferrule and fixing the solder at the front end of the ferrule. The method is characterized in that the optical fiber fixing device is manufactured by a process of filling the rear end of the inner hole of the ferrule with an adhesive.

Further, the present invention provides the above-mentioned production method,
The rear end of the ferrule is locally suctioned.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an optical fiber fixture of the present invention. The optical fiber 1 is inserted into the inner hole 2 a of the ferrule 2, and the coating removal portion 1 b is fixed at the tip of the ferrule 2 by the solder portion 5, and an adhesive 13 is applied to the rear end of the inner hole 2 a of the ferrule 2. The coating removal portion 1b and the coating portion 1a are fixed by filling.

The rear end of the inner hole 2a, which is a region where the adhesive 13 is filled, extends from the front end of the ferrule 2 (the lower side in the drawing) to the rear end of the ferrule 2 (the upper side in the drawing). It has a structure.

Further, the tip of the coating removal portion 1b of the optical fiber 1 protruding from the ferrule 2 is subjected to lens processing or the like, and the coating 1a of the optical fiber 1 which has not been coating removed is provided on the opposite side. Is running.

Next, a method for manufacturing the optical fiber fixture will be described.

The coating portion 1a of the optical fiber 1 is removed by using a tool such as a stripper, and the exposed surface of the quartz glass of the coating removal portion 1b is metallized by gold plating or the like.

The distal end side of the coating removal portion 1b of the optical fiber 1 is inserted into the inner hole 2a of the ferrule 2 from the rear end side, and a solder preform is inserted from the distal end side. By heating by induction heating or laser heating, the solder preform is melted and the tip of the coating removal portion 1b of the optical fiber 1 and the ferrule 2 are soldered to the solder portion 5.
It is joined by.

Thereafter, for example, an epoxy adhesive is dropped from the filling hole 8 to the inner hole 2a as the adhesive 13, and is filled by vacuum defoaming. As a method of vacuum defoaming, after putting into a vacuum oven in an atmosphere heated to about 50 degrees, 100 torr
After evacuating to a degree of vacuum equal to or less than r and holding for 1 minute, returning to atmospheric pressure and further filling the adhesive 13 are repeated.

In the optical fiber fixing device of the present invention, the portion of the inner hole 2a of the ferrule 2 filled with the adhesive 13 has a shape expanding toward the rear end side. Can be reduced.

The adhesive 13 also adheres to the coating removal portion 1b of the optical fiber 1, but the length x
Is 2 mm or more. This is to increase the adhesive strength of the adhesive 13 and facilitate the removal of air bubbles.

Further, an inner hole 2a at the rear end of the ferrule 2 is provided.
The gap y between the (filling hole 8) and the optical fiber 1 is 0.15 mm
Above. This is to facilitate removal of bubbles during vacuum degassing.

AgSn-based solder is used as the material of the solder portion 5, the composition ratio of Ag is in the range of 2 to 10% by weight, and the balance is S.
n is used, and the composition ratio of Ag is 3 to
Preferably it is 6% by weight.

The ferrule 2 usually contains iron, cobalt,
A tube-shaped ferrule made of a Kovar-based alloy made of nickel is used, but a non-metallic material such as ceramic such as zirconia or alumina or glass other than SUS may be used.

For the coating removal portion 1b of the optical fiber, a single mode or multi mode quartz glass fiber can be used.

Further, the coating removing portion 1b of the optical fiber 1
After exposing a quartz part having a diameter of 0.125 mm, the tip is cleaved with a cleaver and a lens is formed, and the exposed part is plated.

The plating is desirably gold plating for the purpose of improving the wettability to the solder portion 5, and the plating thickness is controlled in the range of 0.2 to 10 μm, preferably 0.5 to 5 μm. I do.

Nickel or the like is usually used for plating the underlayer of gold plating. However, the plating is not particularly limited as long as the adhesion with the gold plating is good.
It is controlled in the range of 0.2 to 10 μm, and preferably, it is controlled in a range of 0.1 μm.
5 to 5 μm.

Regarding the metallization between the coating removal portion 1b and the plating, it is desirable to form a film by using a material having good adhesion to both quartz and plating by CVD or PVD from the viewpoint of adhesion. .

The plating of the coating removal portion 1b may be provided on the entire surface or only on the portion fixed by the solder portion 5.

Next, another embodiment of the present invention will be described.

FIG. 2 (a) shows that the filling hole 8 is extended to the vicinity of the outer periphery of the ferrule 2 to increase the gap y and to maximize the bonding length x of the coating removal portion 1b of the optical fiber 1 so as to maximize the adhesive. Promote the filling of 13 ferrules 2
This prevents the generation of bubbles 11. FIG. 2 (b)
As shown in FIG. 2, only the area near the rear end face of the inner hole 2a is increased.
As shown in (c), the inner hole 2a may have a stepped shape like a counterbore.

As shown in FIG. 3, almost all of the bonding portion of the coating removing portion 1b is formed as the bare glass portion 3, so that the bonding strength can be increased.

FIG. 4 is a sectional view showing another embodiment of the method for manufacturing the optical fiber fixture of the present invention.

In FIG. 4A, a guard 7 for preventing liquid dripping is provided at the end of the ferrule 2, and a vacuum oven is set at about 50 ° C., and evacuation is performed to 100 torr or less. By installing the guard 7, even if the foam 10 generated by the adhesive 13 ruptures, it is possible to prevent the dripping 12 as shown in FIG.

Further, in order to promote defoaming, a local exhaust hose 6 can be connected to the rear end of the guard 7 as shown in FIG.

As shown in FIG. 5, the optical fiber fixture manufactured by this method is provided with an adhesive 13 on the rear end of the ferrule 2.
Has a protruding shape.

[0043]

EXAMPLES Here, an experiment was conducted by the following method.

In this experiment, the optical fiber 1 used was a single mode fiber in which the coating removal portion 1b from which the coating portion 1a was removed by 20 mm was plated with Ni 1 μm / Au 1 μm.

The ferrule 2 is made of a metal material of 54% by weight of Fe, 17% by weight of Co, and 29% by weight of Ni.
Those plated with Au 1 μm were used. The adhesive 13 is epoxy resin, and the solder part 5 has Ag 5% by weight and Sn 95% by weight.
Was used.

As an embodiment of the present invention, an optical fiber fixture shown in FIG.
The gap between the gap a and the amount of generated bubbles was examined. Table 1 shows the results.
Shown in

The size of the bubble 11 when it is left standing in a vacuum is substantially fixed, and a gap through which the bubble 11 passes is required between the optical fiber 1 and the filling hole 8. When the gap y is 0.15 mm or more, the amount of generated bubbles is significantly reduced. The same result was obtained in the structures of FIGS. 2A, 2B, and 2C.

[0048]

[Table 1]

Next, as an embodiment of the present invention, FIG.
(B), (c), and an optical fiber fixture shown in FIG. 6 (d) was prepared as a comparative example, and each was tested for tensile strength.
Table 2 shows the results.

FIGS. 2 (a), (b), and (b) of the embodiment of the present invention.
The optical fiber fixing device (c) is superior to the comparative example in that the air bubbles 11 after vacuum degassing were not observed at all, and the coating removal portion 1b of the optical fiber 1, the adhesive 13 and the ferrule 2 were used. Has good adhesion, and the tensile strength is remarkably improved as compared with the comparative example.

This indicates that by widening the filling hole 8 as in the embodiment of the present invention, degassing is easy and the density of the adhesive is high.

When the filling hole 8 is wide, the air bubbles 11 are easily defoamed. However, when the air holes 11 are straight, as shown in FIG. 6D, the air bubbles 11 easily accumulate in the corners, and the adhesion between the coating removing portion 1b and the adhesive 13 is reduced. However, it tends to cause a decrease in tensile strength.

[0053]

[Table 2]

As an embodiment of the present invention, in the case where the metallized coating removing portion 1b of FIG. 1 is bonded to the bare glass portion 3 of FIG. The tensile strength was measured together with (b).

As shown in Table 3, the examples of the present invention were superior in tensile strength as compared with those of the examples of the present invention. In particular, those bonded by the bare glass part 3 had the highest strength. This is because the tensile strength becomes higher when the optical fiber 1 is bonded with the bare glass portion 3 or the coating removal portion 1b, which has higher strength, than when the optical fiber 1 is bonded with the coating portion 1a, which has lower strength.

[0056]

[Table 3]

A similar experiment was conducted by changing the length x of the bonding portion in the optical fiber fixture of FIG. Table 4 shows the results.

It can be seen that the tensile strength is significantly improved when x is 2 mm or more.

[0059]

[Table 4]

FIG. 4 shows an embodiment of the present invention.
The optical fiber fixture shown in FIG. 5 manufactured by using the manufacturing methods of (a) and (b) was prepared, and FIG. 6 (c) was prepared as a comparative example, and the presence or absence of dripping 12 due to foaming 10 was observed. Table 5 shows the results.

Embodiment of the Invention As shown in FIGS. 4A and 4B, the optical fiber shown in FIG. 5 is manufactured by providing a guard 7 on the periphery of the ferrule 2 and further performing local exhaust. FIG. 6 shows a conventional example in which vacuum defoaming is performed independently by a fixture.
Liquid dripping 12 did not occur at all as compared with (c).

[0062]

[Table 5]

[0063]

As described above, according to the present invention, the optical fiber from which the coating at the tip is removed is inserted into the inner hole of the ferrule,
In an optical fiber fixing device in which an adhesive is filled in a rear end portion of a ferrule inner hole while being solder-fixed at a front end portion of the ferrule, an adhesive-filled portion of the inner hole of the ferrule is shaped to spread toward a rear end, The gap between the inner hole and the optical fiber at the rear end is set to 0.15 mm or more, and the length of the portion where the coating removed portion of the optical fiber is bonded to the adhesive is set to 2 mm or more, so that the optical fiber having a high tensile strength is formed. It has become possible to produce a hermetically sealed structure with a high yield without causing dripping of the adhesive.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an optical fiber fixture of the present invention.

FIGS. 2A to 2C are cross-sectional views of another embodiment of the optical fiber fixture of the present invention.

FIG. 3 is a sectional view of another embodiment of the optical fiber fixing device of the present invention.

FIG. 4 is a cross-sectional view illustrating a method for manufacturing the optical fiber fixture of the present invention.

FIG. 5 is a cross-sectional view of the optical fiber fixture manufactured by the manufacturing method of FIG.

FIGS. 6A to 6D are cross-sectional views of a conventional optical fiber fixing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical fiber 1a Coating part 1b Coating removal part 2 Ferrule 3 Bare glass part 4 Exhaust hole 5 Solder part 6 Exhaust hose 7 Guard 8 Filling hole 10 Foaming 11 Bubble 12 Dripping 13 Adhesive 14 Package introduction part 15 Low melting glass solder

Claims (3)

[Claims] 1. An optical fiber fixing device in which an optical fiber having a coating at a tip portion removed is inserted into an inner hole of a ferrule, and is solder-fixed at a tip portion of the ferrule, and an adhesive is filled in a rear end portion of the inner hole of the ferrule. In the above, the adhesive filled portion of the inner hole of the ferrule has a shape expanding toward the rear end, and the gap between the inner hole and the optical fiber at the rear end of the ferrule is 0.1 mm.
An optical fiber fixing device having a length of 5 mm or more, and a length of a portion where an uncoated portion of the optical fiber is adhered with an adhesive is 2 mm or more. 2. An optical fiber whose coating on the tip is removed is inserted into an inner hole of a ferrule, and after soldering is fixed at the tip of the ferrule, a guard is provided at the rear end of the ferrule to prevent the adhesive from dripping, A method of manufacturing an optical fiber fixture, comprising a step of filling an adhesive at a rear end portion of a ferrule inner hole. 3. The method for manufacturing an optical fiber fixing device according to claim 2, wherein in the step of filling the adhesive, the rear end of the ferrule is locally suctioned.