JP2750966B2 - Optical fiber multi-core connector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-core connector for simultaneously connecting a plurality of optical fibers, and more particularly to a multi-core connector having excellent operability, low loss, low reflection and high performance. Things.

[0002]

2. Description of the Related Art FIG. 7 is an exploded perspective view of a conventional multi-core connector A, and FIG. 8 is a longitudinal sectional view showing a connection state of the multi-core connector A. The multi-core connector A includes a pair of multi-core connector plugs 3, 3 ', a pair of guide pins 6, and a clamp spring 7.

A multi-core connector plug 3 has a plurality of optical fibers 2 accommodated in an optical fiber tape 1 arranged and fixed between a pair of guide pin insertion holes 4, and a connection end face 5 of the plug 3 It has a surface orthogonal to the fiber axis. The same applies to the multi-core connector plug 3 ', 4' is a guide pin insertion hole, and 5 'is a connection end face. The connection end faces 5, 5 'are formed by right-angle polishing.

As shown in FIG. 8, the plugs 3 and 3 'are connected to each other by inserting a pair of guide pins 6 into guide pin insertion holes 4 and 4' of the plugs 3 and 3 '. The mounting is performed by applying pressure in the axial direction, and this is held.

At this time, the connection end faces 5, 3 'of the plugs 3, 3'
Microscopically, 5 'has an angle error generated at the time of right-angle polishing. Therefore, if they are joined in this state, a gap is generated between the connection end faces 5 and 5 ', and the light propagating in the optical fiber due to the gap causes Fresnel reflection to return to the light source side. The light emitting characteristics are degraded, and the connection loss is increased due to Fresnel reflection.

Therefore, it is necessary to apply a refractive index matching agent 8, such as silicon grease, to the connection end surfaces 5, 5 'in advance so that no voids are formed. For this reason, at the time of reconnection or switching connection, it is necessary to clean the connection end faces 5, 5 'and apply the refractive index matching agent 8 again in order to prevent the generation of voids due to the shortage of the refractive index matching agent. There is a problem that the workability of attaching and detaching is inferior.

Further, when a large shock due to a drop or the like is applied to the connected multi-core connector A, an external force caused by the shock causes an angle shift between the plugs 3 and 3 ', thereby causing a problem that the connection loss fluctuates. .

FIGS. 9 and 10 show a multi-core connector B aimed at solving the problems of the multi-core connector A. FIG. 9 is an exploded perspective view of the multi-core connector B, and FIG. It is a longitudinal cross-sectional view of the connection state.

In the plug 9 of the multi-core connector B, a plurality of optical fibers in the optical fiber tape 1
Arranged and fixed between the pair of guide pin insertion holes 10, a connection-side end face 11 is provided with a protruding portion 12 in a region surrounding a plurality of optical fibers, and this end face 13 is orthogonal to the optical fiber axis by perpendicular polishing. It has a surface. The other plug 9 '
Similarly, 10 'is a guide pin insertion hole, 11' is a connection end face, 12 'is a protruding portion, and 13' is its end face.

In this multi-core connector B, the protruding portions 12,
By providing 12 ', the angle error at the time of right-angle polishing is suppressed small, and as shown in Fig. 10, when the plugs 9 and 9' are butt-connected, a state where the optical fiber connection end faces are in direct contact with each other is obtained. . Thereby, it is possible to remove Fresnel reflection caused by the gap without using a refractive index bonding agent.

[0011]

However, when viewed microscopically, a processing strain layer having a high refractive index generated during polishing remains on the surface of the optical fiber connection end face. For this reason, at the time of connection, light propagated in the optical fiber causes reflection at the processing strain layer having a high refractive index, and this reflected light returns to the light source side, so that the amount of reflection is practically limited to -40 to -35 dB, and-
It has been difficult to apply it to an analog optical transmission system or the like that requires a low reflection of 50 dB or less.

When the plugs 9 and 9 'are connected, the end faces 13 and 13' of the protruding parts 12 and 12 'come into contact with each other, but the guide pin insertion holes 10 and 11' of the end faces 11 and 11 '.
Since the part around 10 'does not touch,
When external forces in the thickness direction and the width direction of the plugs 9 and 9 'are applied, the ends of the right-angled surfaces of the protruding portions 12 and 12' are fulcrums.
It is easy to cause an angle shift between the plugs 9 and 9 '.

For this reason, an external force applied when the plugs 9 and 9 'are attached or detached or after the connection, the direct contact state of the optical fiber connection end face is destroyed, a gap is easily generated, and stable reflection characteristics and connection loss characteristics are obtained. I couldn't.

When a large impact such as dropping is applied to the connected multi-core connector B, the plugs 9 and 9 '
There has been a problem that a large angular displacement occurs between them, which causes Fresnel reflection due to the air gap and a large connection loss.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical fiber multi-fiber connector which does not require a refractive index matching agent, has improved operability, and has low reflection and low loss characteristics.

[0016]

SUMMARY OF THE INVENTION For this purpose, the present invention provides a method for connecting a plurality of optical fibers arranged between a pair of guide pin insertion holes and fixing a pair of multi-core connector plugs to each other. In a multi-core connector in which a pair of guide pins are butt-connected as a positioning guide,

The multi-core connector plug is formed by plastic molding, and the surface of the plug connection end surface surrounding the optical fiber and the pair of guide pin insertion holes is connected to a surface orthogonal to the optical fiber axis. An inclined surface inclined at an angle larger than the critical angle of total reflection of light propagating through the inside, the connection end surface of the optical fiber is slightly projected and fixed in parallel to the inclined surface, and the space between the multi-core connector plugs is fixed. A guide sleeve having an inner diameter slightly larger than an outer diameter of a terminal portion of the multi-core connector plug as a first guide for alignment, and a pair of guide pins as a second guide for alignment. As a butt connection.

[0018]

According to the present invention, the end faces of the optical fibers are obliquely and directly contacted with each other when the plugs are connected to each other, so that the Fresnel reflection caused by the air gap and the reflection caused by the high refractive index processing strain can be removed. In addition, even when attaching and detaching, it is possible to suppress the occurrence of angular deviation between the plugs with respect to an external force applied after the connection, and it is possible to realize connection characteristics with low reflection and low loss without a refractive index matching agent.

[0019]

Embodiments of the present invention will be described below. FIG. 1 is an exploded perspective view of an optical fiber multi-core connector C of the first embodiment, FIG. 2 is an enlarged perspective view of a plug connection end face portion, and FIG. 3 is a longitudinal sectional view of a plug connection state. The same components as those in FIGS. 7 to 10 are denoted by the same reference numerals. 14 and 14 'are plastic molded multi-core connector plugs, and 15 and 15' are a pair of guide pin insertion holes, respectively.
6, 16 'are plug connection end faces, and 17 is a guide sleeve.

On the connection end face 16 side of the plug 14, a plurality of optical fibers 2 accommodated in the optical fiber tape 1 are provided.
The connection end face 16 is arranged and fixed between the pair of guide pin insertion holes 15 and has an angle larger than the critical angle of total reflection of light propagated in the optical fiber from a plane perpendicular to the optical fiber axis, as shown in FIG. θ, and the connection end face of the optical fiber 2 is the inclined connection end face 16 of the plug 14.
, And has a slight protrusion amount ΔL.

The connection end face 16 of the plug 14 is formed by
It is obtained by obliquely polishing the end (tip) of the plastic molded multicore connector plug 14. The protrusion of the optical fiber connection end face parallel to the plug connection end face 16 by a small amount ΔL can be obtained by performing buff polishing in the final step of oblique polishing.

Since the hardness of the plastic of the material of the plug 14 is smaller than the quartz hardness of the material of the optical fiber 2, the longer the buffing time, the more the plastic is shaved than the quartz. It can be realized by using the phenomenon. This protrusion amount of about 1% of the outer diameter of the optical fiber is sufficient. The same applies to the other plug 14 '.

As shown in FIG. 3, the plugs 14 and 14 'are connected by inserting a pair of guide pins 6 into the guide pin insertion holes of one of the plugs and then connecting the two plugs 14 from both sides of the guide sleeve 17. , 14 'are inserted and matched,
This is performed by inserting the clamp spring 7 and applying pressure in the axial direction, and this state is maintained.

The inner diameter of the guide sleeve 17 is slightly larger than the outer diameter of the plug end (tip). Thus, when the plugs 14 and 14 'are inserted from both sides of the guide sleeve 17, a pair of guide pins previously inserted into the guide pin insertion holes of one plug are automatically inserted into the guide pin insertion holes of the other plug. Is done.

In a state where the two plugs 14 and 14 'are abutted, the optical fibers 2 and 2' are in a state where the inclined surfaces having the tip angle θ are in direct contact with each other. Here, the air gap caused by the angle error at the time of the oblique polishing is such that the optical fiber connection end face slightly protrudes and the plastic molding plugs 14 and 14 ′ are pressed against the pressing force applied in the axial direction by the clamp spring 7 at the time of connection. Are absorbed and do not occur due to compression elastic deformation. Further, damage to the optical fiber connection end face at the time of connection due to the protruding optical fiber connection end face does not occur.

The first reason is that the protrusion amount ΔL is sufficiently smaller than the outer diameter of the optical fiber.
The connection between the guide pins 4 'and the guide sleeve 17 and the pair of guide pins 6 are used as positioning guides.
Since the surfaces surrounding 5 'are also brought into contact with each other at the same time, the lateral displacement does not occur due to the rotation of the plugs 14 and 14', and the optical fiber connection end surfaces come into contact with each other in the aligned state. , 14 ′ are made of an elastic material plastic, so that the impact at the time of connection is reduced by the plugs 14, 14 ′.
It is absorbed by the elastic deformation of the main body.

Therefore, in the connection state of the plugs 14 and 14 ', Fresnel reflection due to the void does not occur, and reflected light caused by the processing strained layer having a high refractive index generated during polishing has an inclined surface having an angle θ. Since the angle θ is larger than the critical angle for total reflection with respect to the optical fiber axis, it does not propagate on the light source side.

Further, even when a large shock due to drop or the like is applied to the connected multi-core connector, the plugs 14, 1
Since the end portion 4 'is accommodated in the guide sleeve 17, the occurrence of angular displacement between the plugs 14 and 14' is suppressed, so that the direct contact state between the plug connection end faces 16, 16 'is maintained. be able to.

As described above, low reflection and low loss connection characteristics can be stably realized without a refractive index matching agent.

Here, the experimental results are shown. The optical fiber tape used in the experiment is a four-core optical fiber tape containing a 1.3 μm band single mode fiber. The outer diameter of the optical fiber is 125 μm, and the mode field diameter is 9.5 μm. To manufacture the Kotanek plug, a plug component having a pair of guide pin insertion holes and four optical fiber insertion holes is formed by molding epoxy resin, and the optical fiber is adhesively fixed in the optical fiber insertion hole. Polishing was performed at an angle of degrees. The cross-sectional dimension of the plug is 7 × 3
mm. The protrusion amount of the optical fiber was set to about 1% of the outer diameter of the optical fiber.

The plurality of plugs manufactured as described above are
The plug selected as a standard was connected without an index matching agent, and the amount of reflection and connection loss were measured. Here, a stainless sleeve was used for the guide sleeve 17, a stainless leaf spring was used for the clamp spring 7, and the pressing force in the axial direction when the plug was connected was about 1 kgf.

As a result of the measurement, the reflection amount was -59 dB on average and -55 dB on average, and the connection loss was 0.3 dB on average and 0.7 dB at maximum for the number of connection cores of 60. Further, the characteristics with the refractive index matching agent were measured and compared with the characteristics without the refractive index matching agent. As a result, the difference between the individual reflection amounts with respect to the number of connection cores 60 was 1 dB or less, and the difference between the individual connection losses. Was 0.1 dB or less, no significant difference was observed between the presence and absence of the refractive index matching agent, and it was confirmed that the optical fiber connection end faces could be connected in a state of direct contact.

Further, the amount of change in the connection loss after the plug was inserted and removed 500 times was 0.15 dB or less at the maximum, and no damage was observed on the optical fiber connection end face after the connection and disconnection. Further, a vibration test (frequency: 10 to 55 Hz, total amplitude: 1.5 mm, vibration direction: orthogonal three axial directions, load time: 2 hours in each direction), and an impact test (acceleration: 100)
G, load time: 6 ms, load direction: three orthogonal axes,
(The number of loads: three times in each direction) As a result, the connection loss fluctuation amount during the test is within a range of the measurement error of 0.03 dB or less at maximum, and the direct contact state between the plug connection end faces against the external force applied to the connection portion. It was confirmed that can be maintained.

FIGS. 4 to 6 show a multi-core connector D according to a second embodiment. FIG. 4 is an exploded perspective view of the multi-core connector D, FIG. 5 is a sectional view seen from above, and FIG. Is a cross-sectional view as viewed from the side. Reference numerals 18 and 18 'denote push-on type multi-core connector plugs, 19 and 19' denote plug cores having the same structure as the plugs 14 and 14 'of the first embodiment, 20 denotes spooping, and 21 and 21' engage. Groove, 22 is a push-on adapter, 23 is a guide sleeve, 24 is a housing,
Reference numeral 25 denotes an engagement elastic claw.

The multi-core connector D of this embodiment includes a pair of push-on type multi-core connector plugs 18 and 18 ′, a pair of guide pins 6, and a push-on type adapter 22. The push-on type multi-core connector plug 18 has
A plug core 19 and a spring 20 for pressing the plug core 19 in the axial direction are incorporated. The same applies to the push-on connector plug 18 '. In the push-on adapter 22, a guide sleeve 23 is housed inside a housing 24 composed of a combination of two pieces.

The inner diameter of the guide sleeve 23 is slightly larger than the outer diameter of the end of the plug core 19 except for both ends, and the inner diameter of both ends is increased in a tapered manner. ing. The inner diameter of the housing 24 is
The portion accommodating the guide sleeve 23 is larger than the outer diameter of the guide sleeve 23, and has a size between the inner diameter and the outer diameter of the guide sleeve 23 on both sides.

Thus, it is possible to house the id sleeve 23 in a floating state inside the housing 24,
The plug cores 19, 19 'can be smoothly inserted into the guide sleeve 23.

Push-on type multi-core connector plug 18,
5 and 6, the pair of guide pins 6 are inserted into the guide pin insertion holes of one plug, and then one plug is inserted from one end of the push-on type adapter 22, as shown in FIGS. Elastic claw 25 of adapter and groove 21 of plug
(Or 21 ′), and the other plug is inserted from the other end of the adapter 22 to similarly connect the elastic claw and the groove.

Here, plugs 18 and 18 'are connected to adapter 2
When the guide sleeve 23 is inserted from both sides of the plug core 2, since the guide sleeve 23 is floating inside the housing 24 and the inner diameter at both ends of the guide sleeve 23 is tapered, The terminal portions 19 and 19 'automatically enter the inside of the guide sleeve 23, and the pair of guide pins 6 previously inserted into one plug core are also automatically inserted into the other plug core.

When the plugs 18 and 18 'are in contact with each other, the plug cores 19 and 19' are connected to each other by the springs 20, 2 '.
At 0 ', the optical fiber is held in a state where it is pressed in the axial direction, and similarly to the first embodiment, the optical fiber connection end faces are held in a state where they are in direct contact with each other obliquely. Also, even when a large impact due to drop or the like is applied to the connected multi-core connector D, the plug cores 19, 1 pressurized by the springs 20, 20 '.
The connection terminal 9 ′ is accommodated in the guide sleeve 23,
In addition, since the guide sleeve 23 can float, the impact is absorbed by the elastic deformation of the springs 20, 20 'and the entire floating of the connection end portions of the plug cores 19, 19'.

As a result, the occurrence of angular deviation between the plug cores 19, 19 'is suppressed, and the direct contact state is maintained. Therefore, similarly to the multi-core connector C of the first embodiment, low-loss and low-reflection connection characteristics can be stably realized without using a refractive index matching agent.

Although the multi-core connector D of this embodiment is applied to a push-on type fastening system, the multi-core connector D may be applied to a screw fastening system or a bayonet fastening system. The same operation and effect as the example can be obtained.

[0043]

As described above, the multi-fiber connector of the present invention has the characteristic that the plastic forming plug exhibits large compression elastic deformation, easily absorbs the polishing angle error of the end face at the time of connection, and has a lower hardness than the optical fiber. While maximizing the characteristic that the optical fiber end face is slightly protruded by the plug end face when polishing the end face,
By using a guide sleeve with a simple structure as a positioning guide in addition to a pair of guide pins, it is possible to ensure that the end faces of the optical fibers directly contact each other on an inclined surface having an angle larger than the critical angle for total reflection. Therefore, there is an advantage that connection between multi-core optical fibers can be achieved with low reflection and low loss without using a refractive index matching agent.
This advantage is more effectively exhibited in the field of optical fiber connection between optical subscriber systems and optical premises systems where the density of optical fiber cables and the number of optical fibers are increasing.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a multicore connector according to a first embodiment of the present invention.

FIG. 2 is an enlarged explanatory view of a terminal portion of a plug of the multicore connector of FIG. 1;

FIG. 3 is a longitudinal sectional view of a connection state of the multicore connector of FIG. 1;

FIG. 4 is an exploded perspective view of a multicore connector according to a second embodiment.

5 is a cross-sectional view of the multi-core connector of FIG. 4 as viewed from above.

FIG. 6 is a cross-sectional view of the multicore connector of FIG. 4 as viewed from the side.

FIG. 7 is an exploded perspective view of a conventional multicore connector.

FIG. 8 is a longitudinal sectional view of the multicore connector of FIG. 7;

FIG. 9 is an exploded perspective view of another conventional multi-core connector.

FIG. 10 is a longitudinal sectional view of the multicore connector of FIG. 9;

[Explanation of symbols]

A: Conventional multi-core connector, 1, 1 ': optical fiber tape, 2, 2': optical fiber, 3, 3 ': multi-core connector plug, 4, 4': guide pin insertion hole, 5, 5 ': Plug connection end face, 6: guide pin, 7: clamp spring,
8: refractive index matching agent, B: another conventional multi-core connector, 9,
9 ': multi-core connector plug, 10, 10': guide pin insertion hole, 11, 11 ': end face on the plug connection side, 12,
12 ': projecting portion, 13, 13': end face of projecting portion,
C: Multi-core connector of the first embodiment of the present invention, 14, 1
4 ': multi-core connector plug, 15: guide pin insertion hole,
16, 16 ': plug connection end face, 17: guide sleeve, D: multi-core connector of the second embodiment of the present invention, 18,
18 ': push-on type multi-core connector plug, 19, 1
9 ': plug core, 20, 20': spring, 21,
21 ': coupling groove, 22: push-on adapter, 2
3: Guide sleeve, 24: housing, 25: elastic claw for connection.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-336509 (JP, A) JP-A-2-186307 (JP, A) JP-A-4-57804 (JP, U) JP-A-5 8509 (JP, U) Japanese Utility Model 1-85807 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) G02B 6/38 G02B 6/40

Claims (2)

(57) [Claims] 1. A pair of guide pins serving as positioning guides between the plug connection end faces of a pair of multicore connector plugs in which a plurality of optical fibers are arranged and fixed between a pair of guide pin insertion holes. In the multi-core connector to be butt-connected, the multi-core connector plug is formed by plastic molding,
A surface of the plug connection end surface surrounding the optical fiber and the pair of guide pin insertion holes is inclined at an angle larger than a critical angle of total reflection of light propagating in the optical fiber with respect to a surface orthogonal to an optical fiber axis. And the connection end face of the optical fiber is slightly protruded and fixed in parallel to the inclined face, and the distance between the multi-core connector plugs is smaller than the outer diameter of the terminal portion of the multi-core connector plug. An optical fiber multi-fiber connector wherein a guide sleeve having a slightly larger inner diameter is used as a first guide for positioning, and the pair of guide pins are butt-connected as a second guide for positioning. 2. A state in which the guide sleeve is housed in a housing and is used as the first guide for positioning, and the guide sleeve has a structure in which an inner diameter increases in a tapered shape at both end portions. The housing has a larger inner diameter than the outer diameter of the guide sleeve in a portion that houses the guide sleeve, and has a gap between the inner diameter and the outer diameter of the guide sleeve on both sides of the portion that houses the guide sleeve. The optical fiber multi-fiber connector according to claim 1, wherein the optical fiber multi-fiber connector has a structure having an inner diameter dimension of: