JP4968122B2 - Optical connector - Google Patents

Description

  The present invention relates to an optical connector for connecting optical fibers composed of a core and a clad.

  In general, a physical connection method in which optical fibers or ferrules into which optical fibers are inserted is generally used as an optical fiber connection method. For example, mechanical splices, SC optical connectors, FC optical connectors, MT optical connectors and the like can be mentioned.

  In addition, after removing the coating of the optical fiber core end, cleaning of the exposed optical fiber, cutting of the optical fiber with a dedicated fiber cutter, fusion splicing using a dedicated fusion splicer, There is also a method of connecting optical fibers by a method such as reinforcement for covering with a protective sleeve.

  The prior art document information related to the invention of this application includes the following.

JP 2002-236234 A JP 2002-323625 A

  However, all of the conventional connection methods require many processes and dedicated tools before starting the connection work, such as removal of the coating of the optical fiber core, cleaning, cutting, and polishing of the optical fiber. This is a connection technique that is not only labor-intensive but is difficult unless it is a skilled worker in optical technology.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an optical connector that makes it easy to handle the connection of optical fibers so that any worker can easily perform the connection work.

  The present invention devised to achieve the above object is an optical connector for optically connecting the end faces of optical fiber core wires covering the outer periphery of an optical fiber composed of a core and a clad, comprising a reinforcing sleeve, A core wire insertion tube provided in the reinforcing sleeve, the end surface of the optical fiber core wire being inserted and abutted against each other, an optical instantaneous adhesive provided between the reinforcement sleeve and the core wire insertion tube, It is formed in a core wire insertion tube, and includes an adhesive supply hole for supplying the optical instantaneous adhesive.

  The instant optical adhesive may be filled in an adhesive bag.

  The core insertion tube has a tapered shape so that the inner diameter becomes large at both ends where the optical fiber core is inserted and becomes small in accordance with the outer diameter of the optical fiber at the center. It is good to be formed.

  The core wire insertion tube may be made of a metal tube or a glass tube.

  The optical instant adhesive may have a refractive index after curing equal to the refractive index of the core.

  The optical instant adhesive may be a cyanoacrylate-based room-temperature curable instantaneous adhesive, a photo-curable instantaneous adhesive, or a one-component or two-component epoxy resin-based room-temperature curable instantaneous adhesive. .

  According to the present invention, connection of optical fibers is easy to handle, and any worker can easily perform connection work.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

  First, an example of an optical fiber core wire connected by the optical connector according to the present embodiment will be described with reference to FIG.

  As shown in FIG. 3, the optical fiber core wire 31 includes an optical fiber 34 including a core 32 and a clad 33 covering the outer periphery thereof, and a coating layer 35 covering the outer periphery of the optical fiber 34. In the present embodiment, as the optical fiber 34, a single mode optical fiber having an outer diameter φ of 125 μm mainly composed of quartz glass that is widely used is used. The core 32 is obtained by adding a refractive index control agent such as Ge to pure quartz so as to have a refractive index of about 1.463. The clad 33 is made of pure quartz and has a refractive index of 1.458.

  The covering layer 35 includes an inner covering layer (primary layer) 35a that is a buffer layer and an outer covering layer (secondary layer) 35b that is a protective sheath. In the present embodiment, the inner coating layer 35a and the outer coating layer 35b are made of ultraviolet (UV) curable resin, and the optical fiber core wire 31 having an outer diameter Φ of 250 μm is used.

  FIG. 1A is a longitudinal sectional view of an optical connector showing a preferred embodiment of the present invention, and FIG. 1B is a sectional view taken along line 1B-1B.

  As shown in FIGS. 1 (a) and 1 (b), the optical connector 1 according to this embodiment includes a reinforcing sleeve 2 and end faces formed only by cutting the optical fiber cores 31a and 31b, or an optical fiber core. After removing the coating layer 35 at the end portions of the wires 31a and 31b and cleaning, cutting with a general tool such as scissors or nippers (without using a dedicated tool such as a fiber cutter) is not performed. It consists of a core wire insertion tube 3 for inserting the end faces and abutting the optical fiber core wires 31a and 31b, and an optical adhesive a provided in the reinforcing sleeve 2.

  The reinforcing sleeve 2 is made of an elastic tubular member made of an elastic material such as rubber or resin. The reinforcing sleeve 2 may have an inner diameter slightly larger than the outer diameter of the core wire insertion tube 3 before the core wire insertion tube 3 and the adhesive bag 5 described later are housed therein.

  The end face formed only by cutting the optical fiber cores 31a, 31b is the end portion of each optical fiber core wire 31a, 31b to be connected using, for example, a general cutting tool such as scissors or nippers (fiber cutter). 3) without using a dedicated tool or the like, and the end face is cut as it is without removing the covering layer 35 of FIG. This end face is not polished.

  The core wire insertion tube 3 is a hard tubular member having an ordinary cylindrical shape. The inner diameter of the core wire insertion tube 3 is a large diameter φb at both ends into which the optical fiber core wires 31a and 31b are inserted. The optical fiber core wires 31a and 31b are formed in a tapered shape so as to have a small diameter φs (φb> φs) in accordance with the outer diameter φ. In the present embodiment, the small diameter φs is slightly larger than 250 μm in order to make the small diameter φs slightly larger than the outer diameter Φ.

  The core wire insertion tube 3 is made of a metal tube formed of a metal having a relatively high strength such as SUS, Al, or Cu, or a glass tube formed of glass such as industrial glass or quartz glass. In the present embodiment, a SUS tube that is balanced in terms of high strength, high thermal conductivity, low cost, and availability is used.

  The core wire insertion tube 3 has an adhesive for penetrating from the outer peripheral surface of the central portion to the inner peripheral surface in the radial direction and supplying the optical instantaneous adhesive a to the central portion of the core wire insertion tube 3. At least one supply hole 4 is formed.

  In the present embodiment, when the optical fiber cores 31a and 31b are brought into contact with the side where the optical instantaneous adhesive a is formed at the center of the core wire insertion tube 3, the unevenness of the end faces of the optical fiber cores 31a and 31b is determined. One adhesive supply hole 4 was formed so as to have a width larger than the distance Lj of the gap generated by. Further, an adhesive bag 5 having a length slightly shorter than the length L of the reinforcing sleeve 2 is disposed so as to cover the upper side of the adhesive supply hole 4.

  Since the outer diameter Φ of the optical fiber core wires 31a and 31b is very small, the core wire insertion tube 3 needs to be manufactured with high accuracy. For this reason, it is good to produce the core wire insertion tube 3 of a desired shape by cutting a tubular member or electric discharge machining.

  The instant optical adhesive a is a resin that is liquid or jelly at room temperature, absorbs moisture in the air, is irradiated with UV, reacts with the main agent and the curing agent added thereto, and separates from the main agent. By mixing the provided curing agent, a reaction (polymerization reaction or cross-linking) occurs even in an unreacted part until then and is cured.

  The optical instantaneous adhesive a is stored in the reinforcing sleeve 2 as an adhesive bag 5 formed by filling a bag such as a thin balloon. The adhesive bag 5 is formed so as to be broken with a relatively small pressing force by pressing it with a finger f.

  The optical instantaneous adhesive a has a refractive index nr after curing equal to that of the core 32 of FIG. 3 (in this embodiment, about 1.463). As the optical instant adhesive a, the transmittance of light transmitted through the optical fiber 34 is high (for example, the transmittance of light having a wavelength of 1.3 μm or 1.55 μm is about 90 to 99%), and depending on additives What can adjust a refractive index is good.

  More specifically, as the optical instant adhesive a, a cyanoacrylate-based room-temperature curable instantaneous adhesive, a photo-curable instantaneous adhesive, or a one-component or two-component epoxy resin-based room-temperature curable instantaneous adhesive. Either of these may be used. In the present embodiment, a cyanoacrylate-based room-temperature curing instant adhesive is used as the optical instant adhesive a. The cyanoacrylate-based room-temperature curable instant adhesive is composed of cyanoacrylate as a main component and absorbs moisture in the air and cures at room temperature.

  In the photocurable instantaneous adhesive, the portion that penetrates between the adherends is instantly hardened as an instantaneous adhesive and can be cured by light anionic polymerization even with light (UV or visible light). This photocurable instantaneous adhesive is an adhesive that combines the merits of the instantaneous adhesive and the photocurable resin.

  The one-component epoxy resin-based room-temperature curable instantaneous adhesive is one that cures at room temperature by the reaction between the main epoxy resin and a curing agent such as polyamines added thereto. Moreover, the two-component epoxy resin-based room-temperature curable instantaneous adhesive is cured at room temperature by mixing the main agent (A liquid) and a separately provided curing agent (B liquid).

  When using a two-component epoxy resin room temperature curing type instant adhesive as the optical instant adhesive a, the adhesive bag is composed of a main agent bag filled with the main agent and a hardener filled with the hardener. The agent bag is formed in two parts, and both the main agent bag and the hardener bag are formed so as to be broken with a relatively small pressing force.

  The length L of the optical connector 1 (the length of the reinforcing sleeve 2) L is 2 to 10 cm, preferably 3 to 8 cm in consideration of the strength of the connecting portion of the optical fiber core wire and the miniaturization of the optical connector itself. More preferably, it is 3-6 cm. The core wire insertion tube 3 may have a length shorter than the length L of the reinforcing sleeve 2.

  Next, a method of connecting the optical fiber cores 31a and 31b using the optical connector 1 will be described.

  First, as shown in FIGS. 1A and 1B, an optical connector 1 is prepared. The optical connector 1 is assembled, for example, by housing the core wire insertion tube 3 in the reinforcing sleeve 2 and expanding the diameter of the reinforcing sleeve 2 and then housing the adhesive bag 5 in the reinforcing sleeve 2.

  Each terminal part of the two optical fiber core wires 31a and 31b to be connected is cut at once by using a general cutting tool such as scissors and nippers, and the core, cladding, and coating layer are collectively cut. After the coating layer 35 is removed and washed, the core and clad are cut using a general cutting tool such as scissors and nippers.

  The end faces of the optical fiber core wires 31 a and 31 b formed by these cutting methods are inserted from both sides of the core wire insertion tube 3 in the reinforcing sleeve 2, and are abutted at the center of the core wire insertion tube 3. When the end surfaces of the optical fiber cores 31a and 31b are butted together, the butting distance (the gap between the end surfaces of the optical fiber cores 31a and 31b) Lj is several tens of μm at the maximum.

  Then, the adhesive bag 5 is broken by applying a relatively small pressing force by pressing it with the finger f from the outside of the reinforcing sleeve 2. At this time, as shown in FIGS. 2A to 2C, the optical instantaneous adhesive a in the adhesive bag 5 described in FIGS. 1A and 1B is inserted into the core. It penetrates into the core wire insertion tube 3 through the adhesive supply hole 4 of the tube 3, and fills the adhesive supply hole 4 in the gap between the end faces of the optical fiber core wires 31a and 31b.

  Finally, the core wire insertion tube 3 may be shorter than the reinforcing sleeve 2, and the optical instantaneous adhesive a flows around the both ends of the core wire insertion tube 3, so All are filled with an optical instant adhesive a.

  Immediately after this, the optical instantaneous adhesive a is instantaneously cured, and the refractive index becomes the same as the core 32 of FIG. 3, and the adhesive portion ha and the cores of the optical fiber cores 31a and 31b are aligned. The connection part 21 of the optical fiber core wire fixed in an (optically coupled) state is obtained.

  The operation of this embodiment will be described.

  The optical connector 1 is provided with a core wire insertion tube 3 in the reinforcing sleeve 2, an adhesive supply hole 4 is formed in the core wire insertion tube 3, and an optical instantaneous adhesive a is provided in the reinforcement sleeve 2. Simple structure and few parts.

  In order to connect the two optical fiber cores 31 a and 31 b using the optical connector 1, these end portions are cut with a general cutting tool such as scissors, and the cut end face is connected to the core wire insertion tube 3. After insertion and butting, it is only necessary to apply a relatively small pressing force by pressing with the finger f from the outside of the reinforcing sleeve 2.

  As a result, the optical instantaneous adhesive a that has come out of the broken adhesive bag 5 as it is is solidified after entering the abutting portion from the adhesive supply hole 4, so that the end surfaces of the optical fiber cores 31a and 31b can be easily light-transmitted. Can be connected together.

  That is, according to the optical connector 1, it is not necessary to cut or end-polish the optical fiber core wires 31a and 31b with a fiber cutter, and anyone can easily connect the optical fibers 34 like electrical wiring. it can. Therefore, the optical connector 1 is a so-called simple optical connector.

  In the optical connector 1, since the adhesive bag 5 filled with the optical instantaneous adhesive a is accommodated in the reinforcing sleeve 2, a relatively small pressing force is applied by pressing the reinforcing sleeve 2 with a finger f. The optical fiber core wires 31a and 31b can be connected to each other only by the operation.

  Since the core wire insertion tube 3 is formed in a tapered shape so as to have a large diameter at both ends and a small diameter at the center according to the outer diameter Φ of the optical fiber core wires 31a and 31b, the optical connector 1 The optical fiber core wires 31a and 31b can be easily inserted into the core wire insertion tube 3.

  Since this core wire insertion tube 3 also serves as a splicing rod for the connector itself and the optical fiber core wire connection portion 21, the optical connector 1 and the optical fiber core wire connection portion 21 may be bent or bent. Not strong.

  Further, since the optical adhesive a used in the optical connector 1 has a refractive index after curing that is equivalent to that of the core 32, the optical fiber core wires 31a and 31b are cut with a general cutting tool. Even if the cut surface is rough (see FIG. 2 (b)), the cured adhesive portion ha and the cores of the optical fiber cores 31a and 31b can be aligned. That is, the cured adhesive portion ha serves as both a matching agent and an adhesive.

  The optical fiber core wire 31 described with reference to FIG. 3 can be separated at the same time that the inner optical fiber 34 is bent by bending and the outer coating layer 35 is also bent. For this reason, irrespective of the presence or absence of the coating layer 35, the optical fiber can be separated (cut) with the coating by folding the optical fiber core wire 31 by hand.

  Therefore, in the optical connector 1, the end faces of the optical fiber cores 31 a and 31 b formed by folding the optical fiber core 31 by hand may be butt-connected in the core wire insertion tube 3.

  Further, a plurality of protrusions that pierce the adhesive bag 5 by a relatively small pressing force such as pressing with the finger f may be formed in the vicinity of the adhesive supply hole 4 on the outer periphery of the core wire insertion tube 3.

  In the above-described embodiment, the optical instantaneous adhesive a filled in the adhesive bag 5 is set to an amount that fills almost the entire volume in the reinforcing sleeve 2 after it is cured to form the adhesive portion ha. The amount may be slightly larger than the entire volume in the reinforcing sleeve 2 after ha formation. In this case, the excess optical instantaneous adhesive a overflowing from both ends of the reinforcing sleeve 2 is hardened, so that the reinforcing sleeve 2 and the optical fiber cores 31a and 31b after the formation of the adhesive portion ha are bonded more firmly. Also, the effect of improving the strength of the connecting portion of the optical fiber core wire can be obtained.

  In the above-described embodiment, the example in which the coating layer 35 uses the optical fiber core wire 31 having the two-layer structure has been described. It may be used.

  In addition, as an optical fiber constituting the optical fiber core wire, a multimode optical fiber may be used when the transmission speed is 10 Gbit / s or less or the total length of the optical fiber is 500 m or less.

  Using the experimental system of FIG. 4, the coating layer 35 at the end portion of the butt connection portion of the optical fiber core wire 31 is removed and cut with scissors. The connection part 21 of the optical fiber core wire was produced through a connector.

  The optical fiber of the optical fiber core 31 uses a normal SMF (single mode optical fiber), the light source 42 is a stabilized light source (LD-MG923A: manufactured by Anritsu) having a wavelength of 1.55 μm, and the optical power detector 43 The power meter (AQ2140: manufactured by Ando Electric Co., Ltd.) was used. A SMF (length 4000 m) with both ends FC connectors 44 was directly connected between the light source 42 and the optical power detector 43 as a reference.

  The connection through the optical fiber core connection portion 21 as described above was performed five times. This connection loss was 0.30 dB or less in all cases. Further, the connection loss and the return loss when the temperature of the connection portion was changed from −40 ° C. to 85 ° C. were substantially constant and did not vary.

  From the above description, if the optical fiber 34 is cut with scissors and the end faces of the optical fibers 34 are connected to each other via the connecting portion 21 of the optical fiber core wire, there is no practical problem with the connection loss. It can also be seen that the optical instant adhesive used in the optical connector only needs to have the same refractive index after curing as that of the core.

  Further, when the covering layer 35 is not removed, that is, when the end faces formed only by cutting the optical fiber cores 31a and 31b are butt-connected in the core insertion tube 3, the evaluation experiment is performed in the same manner as described above. As a result, similar results were obtained.

  Thus, according to the present invention, when connecting an optical fiber, it is possible to reduce time, cost, labor, and the like without requiring a cutting operation or a polishing operation using a dedicated tool such as a fiber cutter. In addition, any worker can easily perform connection work.

  As a result, not only for optical fiber connections in communication applications, but also for industrial products where there are many parts and connection parts such as industrial robots, and it is difficult to apply optical fibers with conventional optical fiber connection technologies. It is possible to easily perform the optical fiber connection work without any trouble.

FIG. 1A is a longitudinal sectional view of an optical connector showing a preferred embodiment of the present invention, and FIG. 1B is a sectional view taken along line 1B-1B. 2A is a longitudinal sectional view of the optical connector (connecting portion of the optical fiber core wires) in a state where the optical fiber core wires are connected to each other, FIG. 2B is an enlarged view of the center portion thereof, and FIG. Is a sectional view taken along line 2C-2C. It is a cross-sectional view which shows an example of the optical fiber core wire connected with the optical connector shown in FIG. 4 (a) and 4 (b) are diagrams for explaining a connection loss evaluation experiment method in the connection portion of the optical fiber core wire using the optical connector of the embodiment shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical connector 2 Reinforcing sleeve 3 Core wire insertion tube 4 Adhesive supply hole a Optical instant adhesive

Claims (6)

  An optical connector for connecting optical fiber end faces of an optical fiber covering an outer periphery of an optical fiber composed of a core and a clad by optical coupling, the reinforcing sleeve, provided in the reinforcing sleeve, of the optical fiber core A core wire insertion tube which is inserted and abutted with the end face; an optical instantaneous adhesive provided between the reinforcing sleeve and the core wire insertion tube; and the optical instantaneous adhesive formed on the core wire insertion tube. An optical connector comprising: an adhesive supply hole for supplying the optical connector.   The optical connector according to claim 1, wherein the optical instant adhesive is filled in an adhesive bag.   The core wire insertion tube is formed in a tapered shape so that the inner diameter becomes large at both ends where the optical fiber core wire is inserted and becomes small at the center according to the outer diameter of the optical fiber core wire. The optical connector according to claim 1 or 2.   The optical connector according to claim 1, wherein the core wire insertion tube is made of a metal tube or a glass tube.   5. The optical connector according to claim 1, wherein the optical instantaneous adhesive has a refractive index after curing equal to a refractive index of the core.   2. The optical instant adhesive is a cyanoacrylate-based room-temperature curable instantaneous adhesive, a photo-curable instantaneous adhesive, or a one-component or two-component epoxy resin-based room-temperature curable instantaneous adhesive. The optical connector in any one of -5.

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