JP2003014971A - Optical fiber splice - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deterioration of properties or temporary poor connection in a high temperature and high humidity environment or vibration environment when the strand of an optical fiber to be measured is inserted from both ends of a through-hole 11a to connect each tip surface. SOLUTION: The optical fiber 12 is fixed to an intermediate part except both ends in a longitudinal direction of the through-hole 11a in an optical fiber splice.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber splice used for connecting two optical fiber strands used for optical communication.

[0002]

2. Description of the Related Art Broadly speaking, methods for connecting optical fibers to each other are roughly divided into an optical connector connection in which the end portions of optical fibers are fixed to a ferrule and are connected as an optical connector, and an end portion of two optical fibers is melted for connection. There are three methods of fusion splicing connection and mechanical splicing connection for connecting the end faces of the optical fiber wires inside the optical fiber splice.

The conventional optical fiber splice is a component for connecting the element wires of two optical fibers to be connected at their tip surfaces, and as a product using the same, not only the mechanical splice described above but also the optical splice is used. It may be used inside a module.

As shown in FIG. 7, the conventional optical fiber splice 50 has a V-shaped groove 51a of an optical fiber aligning member 51 consisting of a V-shaped groove, and an element wire 53a from which the coating of the connected optical fiber 53 is removed. Insert from both ends, align at approximately the center of the V groove 51a, connect the tip surfaces 53b and cover the upper lid 52, and load the upper lid 52 with adhesive or using a spring to fix the strand 1a. There is.

Further, the optical fiber splice 6 shown in FIG.
As described above, the strands 64a of the optical fiber 64 to be connected are inserted from both ends of the through hole 61a of the cylindrical sleeve 61, and the distal end surface 64b is connected at the substantially central portion of the through hole 61a.

Further, as a method of connecting the tip portion 64b,
For the sake of simplicity, the structure of the cylindrical sleeve 61 shown in FIG. 8 will be described. However, as shown in FIG. 9A, the strand 64a of the optical fiber to be connected is coupled inside the through hole 61a of the sleeve 61, There is a method in which a spring 63 is attached to the optical fiber holding member 62 and a compressive force is applied to the tip end surface 64b so as to join them.

Further, as shown in FIG. 9 (b), the optical fiber element wire 64a is bent in a U-shape, and the tip surface 64 is bent by the force.
There is a method of connecting by applying a compressive force in the b direction.

Then, as shown in FIG. 9 (c), the optical fiber element wire 64a is fixed and the tip end surface 64b is coated with a matching oil 71 whose refractive index is matched with that of the optical fiber element wire 1a. There were three methods of connecting via the matching oil 71.

[0009]

However, in any of the conventional optical fiber splices 50 and 60 described above, when the matching oil 71 shown in FIG. 9 (c) is used, high temperature and high humidity are maintained for a long time. In the usage environment, the components of the matching oil 71 are deteriorated, the refractive index is changed, and the phenomenon that the matching oil 71 is eluted due to heat occurs, which deteriorates the optical connection state and interrupts communication. Occurred.

Alternatively, the spring 63 shown in FIG. 9 (a) may be attached to the tip surface 64b by applying a compressive force, or the optical fiber element wire 64a shown in FIG. 9 (b) may be bent into a U shape. In the method in which the tip surface 64b is connected by applying a compressive force to the tip surface 64b by the force, the tip surface 64b is momentarily disengaged when vibration is applied, which causes a problem that communication is interrupted.

This is because the optical fiber aligning member 5 is vibrated.
1 or the inside of the through holes 51a, 61a of the sleeve 61, the tip end surface 64b of the optical fiber element wire 64a floats without being fixed.
The spring force applied to 4b cannot be fully restored, and the so-called momentary disconnection occurs in which the tip surfaces 64b are momentarily disconnected from each other.

As described above, none of the conventional methods can satisfy both the high temperature and high humidity conditions and the vibration conditions.

[0013]

In view of the above-mentioned problems of the prior art, the present invention provides an optical fiber splice for connecting two optical fibers inserted from both sides inside a through hole. The optical fiber element wire is fixed to the intermediate portion excluding the portion, and the tip surfaces of the two optical fibers inserted from both sides of the through hole are brought into contact with both end surfaces of the fixed optical fiber element wire, respectively. It is characterized by having done.

Further, it is characterized in that one or more lateral holes are provided from the outer periphery of the portion where the optical fiber element wire is fixed to the through hole.

Further, in the optical fiber aligning member having the V groove, the optical fiber element wire is sandwiched and fixed by an upper lid at an intermediate portion of the V groove except for both ends in the longitudinal direction, and two optical fibers are inserted from both ends of the V groove. It is characterized in that the tip end face of the optical fiber is brought into contact with both end faces of the fixed optical fiber element wire to be connected.

An optical attenuating fiber is used as the optical fiber.

Moreover, the refractive index of the cladding portion of the optical fiber element wire is two or more layers.

Further, it is characterized in that both end surfaces of the optical fiber element wire have a flat shape, a conical shape, a spherical shape, or a combination thereof.

As described above, by using the optical fiber splice of the present invention, since the optical fiber element wire is fixed in the through hole 11a of the sleeve 11 and the position of the tip surface 12a is the fixed position, the optical fiber is vibrated by vibration. Cannot be disconnected.

Further, since it is not necessary to use the matching oil 71 in particular, deterioration of characteristics does not occur even under high temperature and high humidity conditions.

That is, according to the present invention, it is possible to provide an optical fiber splice which does not cause any problems under high temperature and high humidity conditions and vibration conditions.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1A and 1B are a perspective view and a sectional view showing an optical fiber splice showing an embodiment of the present invention.

In the optical fiber splice 10 of the present invention, an optical fiber element wire 12 and an adhesive 13 are used in an intermediate portion of the sleeve 11 having a through hole 11a in the longitudinal direction except both end portions in the longitudinal direction of the through hole 11a. Fixed.

The tip surfaces of the two optical fibers inserted from both sides of the through hole 11a are brought into contact with both end surfaces of the fixed optical fiber element wire 12 to be connected.

A lateral hole 11b is provided from the outer periphery of the portion where the optical fiber element wire 12 is fixed to the through hole 11a. This lateral hole 11b is not necessarily provided, but when fixing the optical fiber element wire 12 and the inside of the through hole 11a with the adhesive 13, the lateral hole 11b should be provided considering the workability of adhesion and the degree of air bubble escape. Is desirable.

As the coupling method of the present invention, a spring is attached and a compressive force is applied to the end face 12a, or the optical fiber element wire 12 is bent in a U-shape and the force is applied to the end face 12a. It is also preferable to use a method of bonding by applying a heat treatment. Since no matching oil is used, the characteristics will not deteriorate under high temperature and high humidity conditions.

Here, the end face 12a of the optical fiber element wire 12 is
2A has a flat surface shape as shown in FIG. 2A, and has a conical surface shape at the boundary between the outer peripheral surface and the end surface 12a as shown in FIG. 2B, and the end surface 12a is flat. A surface shape, a shape in which the cone in (b) has multiple steps as shown in FIG. 2 (c), a spherical shape as shown in FIG. 2 (d), and FIG. 2 (e) As described above, it is possible to use a conical shape whose end face 12a is substantially spherical.

Of these, the one in which the end face 12a shown in FIGS. 2D and 2E has a substantially spherical shape is more desirable because the end face 12a of the optical fiber element wire 12 can be connected with a slight pressing force. .

In the conventional example, when the vibration is applied, the tip end surface of the optical fiber element wire is not fixed and floats inside the through hole of the sleeve. Therefore, the tip end surface may be added depending on the vibration condition. A problem arises in which the spring force is not fully restored and the connection between the end faces is momentarily disconnected.

On the other hand, in the present invention, since the optical fiber element wire 12 is fixed in the through hole 11a of the sleeve 11 and the position of the end face 12a is a fixed position, the connection of the optical fibers to be connected is also caused by vibration. Can be prevented from coming off.

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

The optical fiber splice 20 shown in FIG.
V of the optical fiber alignment member 21 having the V-shaped groove 21a
The optical fiber element wire 12 is sandwiched by an upper cover 22 and fixed by an adhesive agent 23 at an intermediate portion of the groove 21 a excluding both end portions in the longitudinal direction.

After the upper lid 22 is bonded and fixed, the V groove 21a and the upper lid 2
The portion surrounded by the bottom surface of 2 is designed so that the optical fiber element having a circular cross section can be inserted without gaps at two locations of the V groove 21a and one location of the upper lid 22.

With such a structure, the optical fiber splice 10 in FIG. 3 has a pair of optical fibers inserted from both ends of the V groove 21a like the optical fiber splice 10 shown in FIG. It is possible to abut on the end face of 12 and connect.

Next, the optical fiber splice 10 of the present invention.
As shown in FIG. 4, instead of a single through hole, a plurality of through holes 31a may be provided, and the optical fiber element wire 12 may be fixed to an intermediate portion of each through hole 31a.

In this way, one optical splice 1
With 0, a plurality of combinations of optical fibers can be connected.

As described above, in the optical fiber splice 10 of the present invention, the optical fiber strand 12 is formed in the middle portion of the through holes 11a and 31a or the V groove 21a except both longitudinal end portions.
By fixing the wires, even when the ends of the optical fiber to be connected are inserted from both ends of the through holes 11a and 31a or the V groove 21a and both ends are connected, the characteristics are deteriorated in a high temperature and high humidity environment or a vibration environment. Alternatively, the temporary disconnection, which is a momentary disconnection, no longer occurs.

Although the optical fiber element wire 12 fixed inside the through holes 11a, 31a or the V groove 21a has been described as a general single mode or multimode silica glass optical fiber, the invention is not limited to these. It is possible to use various kinds of optical fibers such as an optical attenuating fiber, a polarization dependent optical fiber, an optical fiber in which the refractive index of the cladding is changed stepwise, a grating fiber, or an optical plastic fiber.

By using an optical attenuating fiber for the optical fiber element wire 12, the transmitted light output is attenuated,
It can also be used as an attenuator.

Further, as shown in FIG. 5 (a), the refractive index of the clad portion of the optical fiber element wire 12 is made smaller than that of the core, and a low refractive index layer is provided between the inner clad and the outer clad. Alternatively, as shown in FIG. 5B, the refractive index of the clad is made smaller than that of the core, and a low refractive index layer is provided in the inner layer of the clad to block the light incident on the clad. Thus, it is possible to prevent the cladding mode from propagating to the connected optical fiber that is connected later.

The optical fiber splice 10 of the present invention can be applied to various purposes by using various optical fiber strands 12.

The material for forming the sleeves 11, 31 or the optical fiber aligning member 21 or the upper lid 22 is not only zirconia ceramics but also crystal particles containing alumina, silicon nitride, silicon carbide, aluminum nitride, cordierite, mullite as a main component. Having a metal, glass such as borosilicate glass, crystallized glass, etc., metal such as stainless steel, iron-nickel alloy, brass, PB
The same effect can be obtained with any material such as T and plastics such as liquid crystal polymer.

Further, the optical fiber wire 12 and the sleeve 1
1, 31 or adhesive 1 with optical fiber alignment member 21
As the adhesive 3, an epoxy resin adhesive, an ultraviolet curable adhesive, an anaerobic adhesive 13 or the like can be used. Further, as the adhesive 13, a metal-based connecting method such as low-melting glass or solder can be used.

Next, the optical fiber wire 12 is attached to the sleeve 1.
A method of fixing the first and the third members will be described.

First, a small amount of adhesive is applied to the outer circumference of the optical fiber element wire 12, and the through holes 11 of the sleeves 11 and 31 are formed.
a, 31a. At this time, the adhesive 13 is not injected into the through hole. Before the optical fiber wire 12 completely enters the through hole 31a, the end surface 11 of the sleeve
Excess adhesive 13 attached to c and 31c is removed.

Next, an adhesive is injected into the lateral hole 11b using a needle or the like, and then the adhesive 13 is hardened.

The detachable mechanical splice has been described above, but the method can be applied to a method in which the optical fiber to be connected is fixed to the optical fiber splice with an adhesive, solder, or low-melting glass so as not to be detached. Is.

As described above, according to the present invention, by fixing the optical fiber element wire to the through hole of the optical fiber splice or the intermediate portion of the V groove except both ends in the longitudinal direction, the optical connecting light is supplied from both ends of the through hole. When the fiber strands were inserted and the respective tip surfaces were connected, deterioration of characteristics or temporary disconnection, which is a temporary connection failure, no longer occurs in a high temperature and high humidity environment or a vibration environment.

The optical fiber splice 10 of the present invention is used as a mechanical splice in a place where an optical fiber is simply assembled on site.

[0051]

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

An optical fiber splice 10 of the present invention shown in FIG. 1 and a conventional optical fiber splice 60 shown in FIG. 8 were prepared as a comparative example. The sleeves 11 and 61 are made of zirconia ceramic, and the through hole has an inner diameter of 126 μm and an outer diameter of 2.5.
mm. The connection method of the tip end surface is that the strands 64a of the optical fiber to be connected are coupled inside the through holes 11a and 61a of the sleeves 11 and 61 shown in FIG. 9A, and the spring 63 is attached to the optical fiber holding member 62. Tip surfaces 12a, 6
A method of applying a compressive force to 4b to bond them was used.

Each of the above-mentioned 10 samples was prepared and the through hole 1
Optical fibers 41 and 42 to be connected are connected in 1a and 61a, light is incident on the optical fiber 41 to be measured from a light source 43 having a wavelength of 1550 nm as shown in FIG. The light output of the light emitted from the optical fiber 42 was measured by the power meter 45. The optical fiber splices 10 and 60 were fixed in the chamber of the vibration test apparatus, and the vibration test was performed while measuring the optical output.

The vibration test conditions were 10 to 55 Hz, total amplitude 1.5 mm, 3 directions, and 2 hours each.

The results are shown in Table 1. Here, the splice loss value before and after the test, its fluctuation value, and the presence or absence of a momentary disconnection that is a momentary disconnection during the test are described.

[0056]

[Table 1]

From the above results, the connection loss values before and after the test were the same, but the instantaneous loss was 5 in the conventional sample.
The sample of the present invention had 0 out of 5 out of 5 defects, while 3 out of 5 had defects.

From the above, the conventional optical fiber splice 6
At 0, the tip end surface 64b of the optical fiber element wire 64a floats inside the through-hole 61a of the sleeve 61 without being fixed due to the vibration.
The spring force applied to 4b cannot be completely restored, and the connection between the tip surfaces 1b is momentarily disconnected.

On the other hand, in the optical fiber splice 10 of the present invention, the optical fiber element wire 12 is fixed in the through hole 11a, and the tip end surface of the optical fiber to be connected is fixed, so that it is momentarily caused by vibration. No disconnection of the tip surface occurred.

[0060]

According to the present invention, in the optical fiber splice of the present invention, the optical fiber element wire is fixed to the through hole or the middle portion of the V groove except both ends in the longitudinal direction. When the strands of the connecting optical fiber were inserted and the respective tip surfaces were connected, deterioration of characteristics or temporary connection failure did not occur in a high temperature and high humidity environment or a vibration environment.

[Brief description of drawings]

1A is a perspective view showing an optical fiber splice of the present invention, and FIG. 1B is a sectional view of the same.

2 (a) to 2 (d) are side views showing shapes of various tip surfaces of the optical fiber strand of the optical fiber splice of the present invention.

3A is a perspective view showing an optical fiber splice of the present invention, and FIG. 3B is a sectional view of the same.

4A is a perspective view showing an optical fiber splice of the present invention, and FIG. 4B is a sectional view of the same.

FIG. 5 is a diagram showing a refractive index distribution of an optical fiber element wire of the present invention.

FIG. 6 is a conceptual diagram showing a vibration test in an example of the present invention.

FIG. 7 is a perspective view showing a conventional optical fiber splice.

FIG. 8 is a perspective view showing a conventional optical fiber splice.

9A to 9C are cross-sectional views showing a state in which an optical fiber element wire is connected to an optical fiber splice.

[Explanation of symbols]

10 Optical fiber splice 11 sleeve 11a through hole 11b Horizontal hole 11c end face 12 Optical fiber strand 12a Tip surface 13 Adhesive 21 optical fiber alignment member 21a V groove 22 Top cover 31 optical fiber alignment member 31a through hole 41 Connected optical fiber 42 Connected optical fiber 43 Laser diode 44 Power meter 45 Vibration tester 50 optical fiber splice 51 optical fiber alignment member 51a V groove 52 Top cover 53 Connected optical fiber 53a strand 53b Tip surface 60 optical fiber splice 61 Sleeve 61a through hole 62 optical fiber holding member 63 spring 64 Connected optical fiber 64a strand 64b Tip surface 71 Matching oil

Claims (6)

[Claims] 1. An optical fiber splice for connecting two optical fibers inserted from both sides inside a through hole, wherein an optical fiber strand is fixed to an intermediate portion of the through hole except both ends in the longitudinal direction, An optical fiber splice, characterized in that the front end faces of two optical fibers inserted from both sides of a through hole are respectively brought into contact with and connected to both end faces of the fixed optical fiber element wire. 2. The optical fiber splice according to claim 1, wherein one or more lateral holes are provided from the outer periphery of the portion where the optical fiber strand is fixed to the through hole. 3. An optical fiber alignment member having a V-groove, an optical fiber element wire being sandwiched and fixed by an upper lid at an intermediate portion of the V-groove except both ends in the longitudinal direction, and the optical fiber is inserted from both ends of the V-groove.
An optical fiber splice, characterized in that the front end surfaces of a plurality of optical fibers are brought into contact with and connected to both end surfaces of the fixed optical fiber element wire. 4. The optical fiber splice according to claim 1, wherein an optical attenuating fiber is used as the optical fiber strand. 5. The optical fiber splice according to any one of claims 1 to 4, wherein the cladding of the optical fiber element has a refractive index of two or more layers. 6. The light according to any one of claims 1 to 5, wherein the shape of both end faces of the optical fiber is flat, conical, spherical or a combination thereof. Fiber splice.