JPH08313762A - Optical connector plug - Google Patents

Abstract

PURPOSE: To provide an optical connector plug with which the reduction of connection loss is possible. CONSTITUTION: At least one piece of optical fibers 3 are arranged between a pair of guide pin insertions holes 4, 4 and a connecting end face 6 is inclined at an angle larger than the total reflection critical angle of the light propagating in the optical fibers to the plane orthogonal with the axes of the optical fibers and the plane inclusive of a pair of the guide pin insertions holes 4, 4. The guide pin insertions holes 4, 4 are curvilinearly formed by respective having bend components (L/Ly) at least in the same direction of a direction where the slope faces upward to the plane inclusive of a pair of the guide pin insertions holes 4, 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called fitting type optical connector which is optically coupled via a guide pin, and more particularly,
The present invention relates to an optical connector plug having low loss connection characteristics.

[0002]

2. Description of the Related Art Conventionally, MF optical connectors and MT optical connectors have been known as optical connectors having guide pin insertion holes. In such an optical connector, the optical coupling is realized by inserting the guide pins into the guide pin insertion holes of the respective optical connectors and mutually positioning the optical fibers while abutting the end faces of the optical fibers.

Conventionally, in such a mating type optical connector, due to a gap caused by an angular error in the connection end face,
Since the propagating light in the optical fiber causes Fresnel reflection and returns to the light source side, a refractive index matching agent such as silicone grease is applied to the connection end face to avoid deterioration of the light emitting characteristics of the light source and increase of connection loss due to this Fresnel reflection. However, no void is created. Therefore, at the time of reconnection, it is necessary to clean the connection end face and apply the refractive index matching agent, and there is a problem that the workability of desorption is poor.

Therefore, in order to solve such a problem, the invention described in JP-A-4-336509 has been proposed. This is an inclined surface in which the connection end surface of the optical connector plug is inclined at an angle larger than the critical angle for total reflection of light propagating in the optical fiber with respect to the surface orthogonal to the optical fiber axis,
Further, the connection end face of the optical fiber is slightly projected and fixed to the inclined face.

[0005]

However, in such an optical connector plug, the inner diameter of the guide pin insertion hole is usually slightly larger than the diameter of the guide pin (for example, about 1 to 3 μm). , When the optical connector plug is joined by bringing the inclined surfaces into contact with each other, the optical connector plug can move by the clearance between the guide pin insertion hole diameter and the guide pin diameter due to the component force in the shearing direction orthogonal to the optical fiber axis. Due to this, there is a problem that a connection loss occurs due to the axis deviation of the optical fiber axis.

For example, when an optical connector with a loss of 0.2 dB is coupled, it is 1 μ in the direction orthogonal to the axis of the optical fiber.
When the position is shifted by m, the connection loss increases to about 0.8 dB.

Therefore, an object of the present invention is to provide an optical connector plug capable of reducing such connection loss.

[0008]

In order to achieve such an object, according to one aspect of the present invention, at least one optical fiber is arranged between a pair of guide pin insertion holes, and a connecting end face is an optical fiber. With respect to a surface orthogonal to the axis and a surface including the pair of guide pin insertion holes, the guide pin insertion holes are inclined at an angle larger than a critical angle for total reflection of light propagating in an optical fiber, and the guide pin insertion holes are provided in the pair of guides. It is characterized in that the connection end face is curved in the same direction as the direction in which the connection end face is upward and has at least a bending component in the same direction in a direction orthogonal to the surface including the pin insertion hole.

In a preferred aspect of the present invention, the amount of curvature of the guide pin insertion hole is larger than the clearance between the guide pin insertion hole and the guide pin.

In a preferred embodiment of the present invention, the clearance between the guide pin insertion hole and the guide pin is 2 μm or less,
The amount of bending is larger than the clearance and is 3 μm or less.

According to another aspect of the present invention, an adhesive agent for fixing an optical fiber is disposed between the guide pin insertion holes and is provided on the side having the curved component with respect to the surface including the pair of guide pin insertion holes. It is characterized by having holes.

[0012]

According to the present invention, when the optical connector plugs having the above structure are coupled to each other via the guide pin, a component force in the shearing direction is generated at the inclined connecting end face. On the other hand, in the direction orthogonal to the plane including the pair of guide pin insertion holes, there is at least a bending component in the same direction, and the guide pin insertion hole is curved and formed in the same direction as the direction in which the connection end surface faces upward. As a result, the guide pin is brought into contact with and positioned at a specific position on the inner surface of the guide pin insertion hole, and a force in a direction canceling the component force is generated. As a result, a canceling force always acts on the optical connector plug, and the connection loss due to attachment / detachment is reduced.

Further, the bending amount of the guide pin insertion hole is
Larger than clearance, especially 2 μm clearance
In the following, the above effect can be further ensured by setting the bending amount to be larger than the clearance and not more than 3 μm.

Further, according to another aspect of the present invention, an adhesive for fixing an optical fiber is placed on a side having a curved component with respect to a surface which is disposed between the guide pin insertion holes and includes the pair of guide pin insertion holes. By providing the holes, the guide pin insertion holes are curved in a predetermined direction due to the contraction action accompanying the curing of the adhesive.

[0015]

Embodiments of the optical connector plug according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows an example of a multi-fiber optical connector to which the present invention is applied.

2 to 4 show an optical connector plug 1 which is a component of the multi-fiber optical connector. The ferrule 2 of the optical connector plug 1 includes a plurality of optical fibers (3-1, 3-2, 3-3, 3-in this embodiment).
The optical fiber group 3 composed of four (4) is embedded in parallel in the lateral direction at equal intervals, and on both sides of the optical fiber group 3 in the arrangement direction, substantially parallel to the central axis P of the optical fiber group 3. A pair of guide pin insertion holes 4 are formed so as to be penetratingly formed at equal distances. 5 is a guide pin insertion hole 4 of the optical connector plug 1 connected to each other.
Is a pair of guide pins that are inserted into. The connection end surface 6 of the optical fiber plug 1 is an inclined surface inclined at an angle larger than the critical angle of total reflection of light propagating in the optical fiber with respect to the surface orthogonal to the central axis P of the optical fiber group 3. There is.

Reference numeral 7 is an optical fiber plug 1 having the above-mentioned structure.
It is a clamp spring that holds the connection end surfaces 6 of the above in a state of abutting each other.

Further, the optical connector plug 1 shown in FIG.
Has an adhesive injection hole 8 for fixing an optical fiber, which will be described later as a second embodiment of the present invention. The adhesive injection hole 8 is arranged between the pair of guide pin insertion holes 4 and 4, and is provided on the side having the curved component with respect to the surface including the pair of guide pin insertion holes 4 and 4.

The center axis of the optical fiber group 3 is the center two optical fibers (3-2 in this example, when the optical fiber group 3 is composed of an even number of optical fibers).
It is located in the middle of 3-3), and when the optical fiber group 3 is composed of an odd number of optical fibers, it is used in the sense that it coincides with the central axis of the central optical fiber.

As shown in FIGS. 2 and 3, the guide pin insertion hole 4 of the optical connector plug 1 according to the first embodiment of the present invention is orthogonal to the plane including the pair of guide pin insertion holes 4 and 4. The connection end face 6 is curved upward in the same direction in which the connection end face 6 faces upward. Then, the bending amount L (that is, the amount of deviation between the central axis of the straight hole and the central axis of the maximum curved portion) becomes larger than the clearance between the guide pin insertion hole 4 and the guide pin 5. Is set to.

If the bending amount L of the guide pin insertion hole 4 is too large, the guide pin cannot be inserted. Guide pin 5 that can be easily handled when the optical connector plug 1 is connected
The insertion and extraction forces of the guide pins are about 300 g or less, and therefore the bending amount of the guide pin insertion hole 4 is preferably set to an amount that satisfies the insertion and extraction forces. As a preferable example thereof, the bending amount L of the guide pin insertion hole 4
Is larger than the clearance, especially the clearance is 2
When the thickness is less than or equal to μm, the amount of curvature L is preferably larger than the clearance and less than or equal to 3 μm. Clearance is 0.5
The average splice loss is 0.2 when the bending amount L is 1 μm at μm.
It was dB.

The optical connector plug 1 according to the present invention
The optical connector plug 1 will be manufactured by transfer molding using a thermosetting resin. A molding pin having the same diameter as that of the guide pin is arranged in the mold, and the guide pin insertion hole 4 that is curved is provided by hardening the resin while pressing the center of the pin to give the pin a slight bend. An optical connector can be obtained.

Optical connector plug 1 constructed as described above
When connecting the two, first insert the guide pin 5 into the guide pin insertion hole 4 of the one optical connector plug 1, and then
The guide pins 5 protruding from the one optical connector plug 1 are inserted into the guide pin insertion holes 4 of the other optical connector plug 1 until the connecting end surfaces 6 come into contact with each other. Then, due to the inclination of the connection end face 6, as shown in FIG. 5, a component force F in a direction in which the optical connector plug 1 is displaced in the axial direction acts. However, the guide pin insertion hole 4 is more than the clearance between the guide pin insertion hole 4 and the guide pin 5 in a direction orthogonal to the surface including the pair of guide pin insertion holes 4 and 4 and the connection end surface 6 is directed upward. Since the guide pin 5 is curved so as to be convex in the direction, the guide pin 5 is positioned in contact with a specific position on the inner surface of the guide pin insertion hole 4, and a force R in a direction canceling the component force F is generated. Therefore, the axis shift of the optical connector plug 1 due to the inclination of the connection end face 6 is prevented.

Next, a second embodiment of the present invention will be described.

In the above embodiment, the guide pin insertion hole 4
However, in the present embodiment, the case where the inclined surface of the connection end surface 6 which is orthogonal to the surface including the pair of guide pin insertion holes 4 and 4 is upwardly curved is convexly formed in the same direction. Is not perpendicular to the plane including the pair of guide pin insertion holes 4 and 4, but the guide pin insertion hole 4 is curved so as to have a bending component in the orthogonal direction.

That is, although not shown, the pair of guide pin insertion holes 4 and 4 is a surface including the pair of guide pin insertion holes 4 and 4, that is, the parallel direction of the optical fiber group 3 is the X-axis direction, and When the direction passing through the central axis P of the fiber group 3 and orthogonal to the X axis is defined as the Y axis direction, the inclined surface of the connection end surface 6 is the same in the direction in which the inclined surface is upward with a plane symmetry relationship with respect to a surface including the Y axis. It is curved so as to be convex in the direction.

Of these, the forces due to the bending component Lx in the direction parallel to the plane including the X axis are canceled by each other, and both optical connector plugs 1 are positioned in the X axis direction. Then, the force due to the bending component Ly in the direction parallel to the surface including the Y axis prevents the optical connector plug 1 from being displaced from the axis due to the inclination of the connection end face 6 as in the first embodiment.

A method of manufacturing the optical connector plug 1 according to the second embodiment will be described. In the previous embodiment, a molding pin having the same diameter as the guide pin is arranged in the mold by transfer molding using thermosetting resin. The optical connector plug 1 having the curved guide pin insertion hole 4 was obtained by hardening the resin while pressing the center portion of the pin to give a slight bend to the pin. The guide pin insertion hole 4 is formed in a curved shape by utilizing the contraction effect associated with the curing of the adhesive for fixing the fiber.

That is, as described above, the ferrule 2 is connected to the optical connector plug 1 by the pair of guide pin insertion holes 4,
4 between the pair of guide pin insertion holes 4, 4
The transfer molding is performed in such a manner that the adhesive injection hole 8 having a substantially rectangular cross section is provided on the side having the curved component with respect to the surface including the above, and the pair of straight guide pin insertion holes 4 and 4 is provided. Here, the ferrule 2 is formed by using a thermosetting epoxy resin containing silica powder as a filler at about 80%. Then, an optical fiber 3 is attached to the ferrule 2.
After mounting, the epoxy-based thermosetting resin adhesive 9 is injected into the adhesive injection hole 8. The core of the optical fiber 3 is inserted into an optical fiber hole 10 formed from the adhesive injection hole 8 to the connection end face 6, and an optical fiber tape including a plurality of cores is provided at the center of the adhesive injection hole 8. Has been extended to the department.

Thus, the injected adhesive 9 shrinks when it hardens, and the ferrule 2 is slightly warped due to this shrinkage. As a result, the guide pin insertion hole 4 is also curved inwardly upward when viewed from the direction of the adhesive injection hole 8, that is, the direction of the central axis P. As shown in FIGS. 6B and 6C, the warp of the ferrule 2 occurs around the adhesive injection hole 8, and the amount of deformation corresponds to the amount of curing shrinkage depending on the type of adhesive.

According to experiments conducted by the inventors, when the ferrule 2 has a total length of 8 mm, the optical fiber hole 10 has a length of 2 mm, and the adhesive injection hole 8 has a bottom portion length of 4 mm, the guide pin insertion hole 4 is curved. An amount of about 3 μm was obtained. At this time, the tip of the optical fiber 3 is inserted into the optical fiber hole 10, and it is hardly affected by the warp of the ferrule 2, and even if the adhesive injection hole portion is locally bent, the bending radius thereof is small. Was 30 mm or less, and it was confirmed that the loss was not affected.

[0033]

As described above, according to one aspect of the present invention, the connection loss of the optical connector can be reduced.

According to another aspect of the present invention, it is possible to easily manufacture the optical connector plug having the curved guide pin insertion hole.

[Brief description of drawings]

FIG. 1 is a perspective view showing an outline of an optical connector to which the present invention is applied.

FIG. 2 is a perspective view showing an optical connector plug according to an embodiment of the present invention.

3 is a sectional view taken along the line aa of FIG.

FIG. 4 is a sectional view taken along line bb of FIG.

FIG. 5 is an enlarged sectional view showing the relationship between the guide pin and the insertion hole of the embodiment of the present invention.

FIG. 6 is a cross-sectional view of an optical connector plug for explaining a second embodiment of the present invention, FIG.
(B) shows a cross section of the optical fiber portion when the adhesive cures and shrinks, and (C) shows a guide pin insertion hole portion cross section when the adhesive cures and shrinks.

[Explanation of symbols]

 1 Optical Connector Plug 2 Ferrule 3 Optical Fiber (Group) 4 Guide Pin Insertion Hole 5 Guide Pin 6 Connection End Face 7 Clamp Spring 8 Adhesive Injection Hole 9 Adhesive P Center Axis

Front page continuation (72) Toru Yamanishi Toru Yamanishi 1 Taya-cho, Sakae-ku, Yokohama-shi, Kanagawa Sumitomo Electric Industries, Ltd. Yokohama Works (72) Inventor Shinji Nagasawa 1-6, Uchiyuki-cho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (4)

[Claims] 1. An optical fiber in which at least one optical fiber is arranged between a pair of guide pin insertion holes, and a connection end surface is a surface orthogonal to an optical fiber axis and a surface including the pair of guide pin insertion holes. Inclined at an angle larger than a critical angle for total reflection of light propagating in the guide pin insertion hole, and the guide pin insertion hole has at least a bending component in a direction orthogonal to a plane including the pair of guide pin insertion holes. Then, the optical connector plug is characterized in that the connection end surface is curved in the same direction as the upward direction. 2. The optical connector plug according to claim 1, wherein a bending amount of the guide pin insertion hole is larger than a clearance between the guide pin insertion hole and the guide pin. 3. The optical connector plug according to claim 1, wherein a clearance between the guide pin insertion hole and the guide pin is 2 μm or less, and the bending amount is larger than the clearance and 3 μm or less. 4. An adhesive injection hole for fixing an optical fiber is provided between the guide pin insertion holes, and an adhesive injection hole for fixing an optical fiber is provided on a side having the curved component with respect to a surface including the pair of guide pin insertion holes. The optical connector plug according to any one of claims 1 to 3.