JP2005338171A - Optical connection structure and connector provided with same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical connection structure of optical fibers or the like which permits a gap between optical fiber end faces, end face slopes, end face roughness, face waviness or the like to some extent and can eliminate an air layer at the time of connection without the need of more advanced structure and treatment. <P>SOLUTION: In the optical connection structure between optical fibers, a socket and plug for holding the optical fiber are provided, and at least one silicone gel ball is held by depression between the end faces of both optical fibers. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical connection structure and an optical fiber connector using the optical connection structure, and more particularly to an optical connection structure for connecting optical fibers to each other using silicone gel balls and an optical fiber connector using the optical connection structure.

  The transmission efficiency of an optical transmission line using an optical fiber is greatly influenced by the connection loss at the optical connection between optical fibers in the optical transmission line and between the optical fiber and other optical components. It is greatly influenced by the connection loss at the connection between the optical fibers. There are two causes of connection loss in the connection between optical fibers: one caused by the connection technology and the other caused by the optical fiber itself. In addition, there are inclinations of the end face of the optical fiber, end face roughness, end face waviness, and the like due to the optical fiber itself.

  In order to remove these causes effectively, a connector used for connection has a complicated structure, or an optical fiber end face is polished with high accuracy. Also, the current situation is that skilled techniques are required to handle such connectors. These measures have led to a significant increase in the cost of connecting optical fibers. The increase in cost in such a connection structure is a major obstacle to the widespread use of optical systems for information transmission, which are typical applications of optical fibers, for example, widespread use of optical systems in offices and homes. Yes. In particular, when an optical system is used in an office or home, there are many connection points and there are many opportunities for switching connections. Therefore, the high cost of the connection structure reduces the cost performance of the optical system, and becomes an obstacle to the spread of the optical system. In other words, in order to widely spread the optical system to offices and homes, for example, it is an important requirement to enable connection at the same cost level as in conventional electrical wiring.

In order to reduce the cost of the connection structure, for example, a connection structure (see, for example, Patent Document 1) in which a silicone gel pad is pressed and held between the end surfaces of both optical fibers to be connected is disclosed. When connecting, there is a case where an air layer is formed between both optical fibers, and if this air layer is formed, there is a problem that reflection of light at the end face of the optical fiber increases and connection loss increases.
JP-A-10-111429

  In view of the above problems, the object of the present invention is to prevent gaps between optical fiber end faces, end face inclination, end face roughness, end face waviness, etc. to some extent without requiring a more sophisticated structure or processing in a connection structure such as an optical fiber. An object of the present invention is to provide an optical connection structure that allows and eliminates an air layer during connection.

  As a result of intensive studies to solve such problems, the present inventor has arranged at least one silicone gel ball between both optical fibers and pressed and held the gap between the optical fiber end faces, The inventors have found that a simple and high-performance connection with a small connection loss can be realized by permitting a certain degree of end surface inclination, end surface roughness, end surface waviness and the like, and eliminating an air layer at the time of connection.

  That is, according to the first aspect of the present invention, in the optical connection structure between optical fibers, the optical fiber holding socket and the plug are held, and at least one silicone gel ball is pressed and narrowed at both optical fiber end faces. An optical connection structure characterized by being held is provided.

  According to a second aspect of the present invention, there is provided the optical connection structure according to the first aspect, wherein the silicone gel ball has a diameter not more than 0.9 times the inner diameter of the socket and the plug. The

  According to the third invention of the present invention, in the first invention, when one silicone gel ball is used, the diameter of the silicone gel ball is 0.6 to 0.9 times the inner diameter of the socket and the plug. An optical connection structure is provided.

  According to a fourth aspect of the present invention, there is provided an optical fiber connector equipped with the optical connection structure according to any one of the first to third aspects.

  According to the present invention, even if the cause of connection loss is allowed to some extent, a high-performance connection with sufficiently low connection loss can be realized, contributing to the spread of an optical system to offices and homes where a low-cost and simple optical connection structure is desired. it can.

  In the optical connection structure of the present invention, at least one silicone gel ball is disposed between the end faces of both optical fibers, and a socket and a plug for holding the optical fiber are tightened and pressed to be held therebetween. The components, production, performance, etc. will be described in detail below.

  The silicone gel ball of the optical connection structure of the present invention is prepared from a silicone gel. The silicone gel used in the present invention is easily deformable due to the properties of siloxane bonds, has low creep properties, has high heat resistance, is thermally stable, has high chemical stability, and has a light transmittance of 90% or more. High transparency can be easily obtained, the refractive index can be easily adjusted and the distribution thereof can be easily adjusted. Therefore, it has a function of imparting adhesiveness to the molded product and adhering to any end face when pressed.

  As the silicone gel, those conventionally used and commonly used as various commercially available silicone materials can be appropriately selected and used. Therefore, any of a heat curing type or a room temperature curing type, a condensation type or an addition type, etc. can be used. In addition, the group bonded to the silicon atom is not particularly limited, and examples thereof include alkyl groups such as methyl group, ethyl group, and propyl group, cycloalkyl groups such as cyclopentyl group and cyclohexyl group, vinyl groups, and allyl groups. In addition to aryl groups such as alkenyl groups, phenyl groups, and tolyl groups, those in which the hydrogen atoms of these groups are partially substituted with other atoms or linking groups can be mentioned.

The silicone gel used in the present invention preferably has a penetration of JIS K2207-1980 (50 g load) after curing in a range of 5 to 200. When a silicone gel having such a softness is used, It is advantageous in adhesion.
Here, the penetration is a value obtained in accordance with JIS K 2207-1980.

The silicone gel ball used in the present invention is spherical and can be produced by a known method in which the silicone gel is cured in a constant temperature fluid.
The diameter of the silicone gel ball is preferably 0.9 times or less, more preferably 0.3 to 0.9 times the inner diameter of the socket and plug for holding the optical fiber of the connection target optical fiber. When the diameter of the silicone gel ball exceeds 0.9 times the inner diameter of the socket and plug that holds the optical fiber to be connected, the air layer cannot be completely eliminated.
In the present invention, when only one silicone gel ball is used, the diameter of the silicone gel ball is preferably 0.6 to 0.9 times the inner diameter of the socket and plug that hold the optical fiber of the connection target optical fiber. If the inner diameter of the socket and plug that holds the optical fiber of the connection target optical fiber is less than 0.6 times, the end face of the optical fiber may not be completely covered.
In the present invention, it is possible to use a plurality of silicone gel balls. When a plurality of silicone gel balls are used, the diameter of the silicone gel balls used is within the above range and is relatively small. The silicone gel balls need not be the same. The fact that the diameters of the silicone gel balls need not be the same means that the silicone gel ball diameter may vary slightly if the connection loss in the connection structure is within an allowable range. This has the advantage that the diameter control in manufacturing need not be severe.

  When the silicone gel ball in the present invention is interposed in the optical connection structure between the optical fibers and is pressed between the two optical fibers to be connected at the respective end faces, the silicone gel ball is applied by the pressing force applied to both optical fibers. Is easily deformed, whereby a state is obtained in which the silicone gel balls are tightly adhered to the end face of each optical fiber without a gap. In other words, even if the end face of the optical fiber is inclined or rough, it can be easily adapted to this, and the wetness can be added to this familiarity, so that a connection state according to adhesive connection can be obtained. . Therefore, even if the optical transmission body has end face defects such as end face inclination, end face roughness, and end face waviness, the connection loss due to these can be effectively reduced. Further, by making use of the fact that the refractive index can be easily adjusted, the refractive index of the silicone gel ball can be made to substantially coincide with the optical fiber to be connected, whereby reflection at the connection interface can be substantially eliminated. This means that the optical gap between the end faces of both fibers can be substantially eliminated, and the reflection loss due to the gap can be effectively eliminated. Furthermore, since the silicone gel ball is a sphere having a diameter not larger than 0.9 times the inner diameter of the socket and plug for holding the optical fiber, it has a feature that the air layer can be completely eliminated.

  In the present invention, when the above silicone gel ball is used, a silicone gel ball coated with silicone oil may be used. By doing in this way, it can prevent more effectively that a bubble remains in the contact | adherence interface with an optical fiber with the silicone oil stably adhered to the silicone gel ball, and can improve connection performance further.

In the optical connection structure of the present invention, the silicone gel ball is disposed between the end faces of both optical fibers to be connected, and the silicone gel ball is pressed between the two.
As a specific example, an example in which one silicone gel ball is used will be described with reference to the drawings. 1 and 2 are schematic cross-sectional views for explaining the state of the optical connection structure portion of the present invention. In FIG. 1, an end face of an optical fiber 1 covered with one protective layer 6 to be connected is attached to a socket 3, and an optical fiber 2 covered with the other protective layer 7 is attached to a plug 4. The silicone gel balls 5 are disposed between the both end faces of FIG. 2, and the silicone gel balls are fastened by fastening the socket 3 and the plug 4 in FIG. At that time, air is excluded from the gap between the socket and the plug, and no longer exists between both end faces of the optical fibers 1 and 2.

  The optical joint structure connected by such silicone gel balls has a high thermal stability and chemical stability and a low creep property of the silicone gel, so that it can be used for a long period of time even under conditions with a large temperature atmosphere change. Furthermore, the silicone gel ball has an advantage that even if a problem occurs in the silicone gel ball, it can be easily replaced.

  In addition, the optical connection structure according to the present invention is even more useful for a plastic optical fiber that is expected to be frequently used in an optical system in an office or home. In other words, optical cables using plastic optical fibers are lower in cost than silica-based optical fibers that are frequently used in the trunk systems of optical systems for information transmission, and the core diameter is much larger and easier to handle. It has features suitable for home use, but on the other hand, it is difficult to perform advanced end surface treatment, and even if sufficient end surface processing is performed, the end surface is easily damaged in the process of repeatedly attaching and detaching connectors. . In this way, it is difficult to avoid the cause of connection loss related to the end face due to its characteristics, but according to the optical connection structure of the present invention, the silicone gel ball functions as described above. Such defects can be effectively covered.

  The optical fiber connector of the present invention is a connector equipped with the optical connection structure described above. The end of each optical fiber to be connected is held by a socket and a plug, and the socket and plug of each connector are fitted into a sleeve. The optical fibers are optically connected to each other by aligning them. A silicone gel ball is arranged in the socket, and each end face of both optical fibers presses and holds the silicone gel ball when the socket is fitted to the sleeve of the plug and the plug.

  The optical connection structure of the present invention can be used not only for connecting optical fibers having similar diameters but also for optical connection between an optical fiber having a large emission region and an optical fiber having a small incident region or a light receiving semiconductor.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited by these examples without departing from the gist thereof. In addition, the physical property measuring method is as follows.
(1) Connection loss: Connected to a transceiver (TODX2402 manufactured by Toshiba Corp.), measured the optical power of a certain length of optical fiber, then attached a connection structure to the fiber, and similarly measured the optical power, The connection loss was obtained from the following equation.
Connection loss = 10 log (P1 / P2)
(However, P2: Optical power measured first, P1: Optical power when connection structure is connected)
(2) Penetration: Determined according to JIS K 2207-1980.

(Example 1)
A silicone gel (SIG4000 (trade name): Shin-Etsu Chemical Co., Ltd.) with a penetration of 145, with a 2 mm inner diameter socket and plug as shown in FIG. A silicone gel ball having a diameter of 1.5 mm obtained from Kogyo Co., Ltd. was placed and pressed and connected as shown in FIG. The connection loss of the obtained connection structure was 0.2 dB.

(Comparative Example 1)
An optical fiber was connected in the same manner as in Example 1 except that the silicone gel ball was not used. The connection loss of the obtained connection structure was 11 dB.

(Comparative Example 2)
An optical fiber was connected in the same manner as in Example 1 except that a gel pad having a thickness of 1.0 mm was used instead of the silicone gel ball. The connection loss of the obtained connection structure was 1.1 dB. This is probably because the air layer could not be completely removed from the connection.

(Comparative Example 3)
An optical fiber was connected in the same manner as in Example 1 except that the diameter of the silicone gel ball was 2.0 mm. The connection loss of the obtained connection structure was 0.9 dB. This is probably because the air layer could not be completely removed from the connection.

  According to the optical connection structure of the present invention, the silicone gel ball that connects the optical fibers can obtain high connection performance without subjecting the end faces of the optical fibers to sophisticated polishing. Further, since reflection loss due to the air layer existing in the gap can be prevented, high-performance connection can be easily performed using a simple connector manufactured by a technique such as injection molding.

It is typical sectional drawing explaining the state before tightening of the optical connection structure part of this invention. It is typical sectional drawing explaining the state which the optical connection structure part of this invention fastened.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical fiber 2 Optical fiber 3 Socket 4 Plug 5 Silicone gel ball 6 Protective layer 7 Protective layer

Claims (4)

  In an optical connection structure between optical fibers, an optical connection structure having a socket and a plug for holding an optical fiber, and pressing and sandwiching at least one silicone gel ball at both optical fiber end faces .   2. The optical connection structure according to claim 1, wherein the diameter of the silicone gel ball is 0.9 times or less of the inner diameter of the socket and the plug.   2. The optical connection structure according to claim 1, wherein the diameter of the silicone gel ball when one silicone gel ball is used is 0.6 to 0.9 times the inner diameter of the socket and the plug.   An optical fiber connector equipped with the optical connection structure according to claim 1.

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