JP4835618B2 - 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 coupling and connecting the end faces of optical fiber cores covering the outer periphery of an optical fiber consisting of a core and a cladding, A core insertion tube provided in the heat contraction tube and inserted and abutted by inserting an end face of the optical fiber core; an uncured refractive index provided between the heat contraction tube and the core insertion tube A matching resin and a resin supply hole formed in the core wire insertion tube for supplying the uncured refractive index matching resin are provided.

  A resin bag filled with the uncured refractive index matching resin or a resin tube formed with the uncured refractive index matching resin may be housed in the heat shrinkable tube.

  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. It is good to be done.

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

  The refractive index matching resin may have a refractive index after curing equal to the refractive index of the core.

  The refractive index matching resin may be a thermosetting resin or an ultraviolet curable resin.

  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 FIG. 1A and FIG. 1B, the optical connector 1 according to this embodiment is formed only by cutting a heat-shrinkable tube (thermal reinforcing sleeve) 2 and optical fiber cores 31a and 31b. After removing the coating layer 35 on the end face or the end portions of the optical fiber cores 31a and 31b and cleaning them, cutting with a general tool such as scissors and nippers (without using a dedicated tool such as a fiber cutter) Each of the end surfaces not subjected to the polishing treatment is inserted into the optical fiber cores 31a and 31b, and the uncured refractive index matching resin sr provided in the heat shrinkable tube 2.

  The end surfaces formed only by cutting the optical fiber cores 31a and 31b are the ends of the optical fiber core wires 31a and 31b to be connected to each other by using, for example, a general cutting tool such as scissors and nippers. It is the end surface cut | disconnected as it was, without removing the coating layer 35 of this. 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 has a relatively high strength such as SUS, Al, or Cu, and is a metal tube formed of a metal having high thermal conductivity, or glass formed of glass such as industrial glass or quartz glass. It consists of a tube. 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 penetrates from the outer peripheral surface of the central portion to the inner peripheral surface in the radial direction, and supplies uncured refractive index matching resin sr to the central portion of the core wire insertion tube 3. At least one resin supply hole 4 is formed. In this embodiment, when the optical fiber cores 31a and 31b are abutted with the side where the refractive index matching resin sr 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 caused. One resin supply hole 4 was formed so as to have a width larger than the distance Lj of the generated gap. Further, a resin bag 5 having a length slightly shorter than the length L of the heat shrinkable tube 2 was disposed so as to cover the upper side of the resin 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 uncured refractive index matching resin sr is a liquid or jelly-like resin at room temperature, and generally has a net-like structure, and is not yet heated by being heated or irradiated with UV. The reaction occurs even in the reaction part, and the network becomes stronger and hardened.

  The uncured refractive index matching resin sr is stored in the heat-shrinkable tube 2 as a resin bag 5 formed by filling the resin in a bag such as a thin balloon. The uncured refractive index matching resin sr has a cured refractive index nr equivalent to that of the core 32 of FIG. 3 (in this embodiment, about 1.463).

  As the refractive index matching resin sr, a thermosetting resin or a UV curable resin may be used. In the present embodiment, a thermosetting resin is used as the refractive index matching resin sr. As a thermosetting resin having a refractive index after curing equivalent to that of the core 32 in FIG. 3, a resin having a visible region transmittance of 99% or more and whose refractive index can be adjusted by an additive or the like is preferable. Adeka Nano Hybrid Silicone (FX-T350) manufactured by Denka Co., Ltd. can be used.

  Further, as the UV curable resin having a refractive index after curing equivalent to that of the core 32 in FIG. 3, a resin whose refractive index can be adjusted by an additive or the like is preferable. As an example, Adeka Nano Hybrid Silicone (FX-) manufactured by Asahi Denka Co., Ltd. V550) can be used.

  The length L of the optical connector 1 is 2 to 10 cm, preferably 3 to 8 cm, and more preferably 3 to 6 cm in consideration of the strength of the connecting portion of the optical fiber core wire and the miniaturization of the optical connector itself. Good. The core wire insertion tube 3 may have a length shorter than the length L of the heat-shrinkable tube 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. 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 heat shrinkable tube 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 whole heat shrinkable tube 2 is heated using a simple heating instrument such as a handy hot plate, a dryer, or a soldering iron, and the heat shrinkable tube 2 is contracted. At this time, as shown in FIGS. 2A to 2C, the resin bag 5 is broken by the shrinkage force of the heat shrinkable tube 2, and the uncured refractive index matching resin sr in the resin bag 5 is the core wire. It penetrates into the core wire insertion tube 3 through the resin supply hole 4 of the insertion tube 3, and fills the resin supply hole 4 with the gap between the end faces of the optical fiber core wires 31a and 31b. Finally, almost all of the heat-shrinkable tube 2 after shrinkage is filled with the uncured refractive index matching resin sr.

  Simultaneously with the shrinkage of the heat shrinkable tube 2, the uncured refractive index matching resin sr is gradually cured, and when all the uncured refractive index matching resin sr is cured, the refractive index is equal to that of the core 32 of FIG. The refractive index matching resin r is obtained, and the optical fiber core wire connecting portion 21 fixed in a state where the refractive index matching resin r and the cores of the optical fiber core wires 31a and 31b are matched (optically coupled) is obtained.

  The operation of this embodiment will be described.

  The optical connector 1 is provided with a core insertion tube 3 in the heat shrinkable tube 2 and a resin supply hole 4 formed in the core wire insertion tube 3, and an uncured refractive index matching resin sr is placed in the heat shrinkable tube 2. It has a simple structure and a small number of 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 inserting and matching, it is only necessary to heat with a simple heating tool such as a handy hot plate.

  As a result, after the uncured refractive index matching resin sr that has come out of the broken resin bag 5 as it is, or the uncured refractive index matching resin sr that has been melted by applying heat enters the butt portion from the resin supply hole 4. Since it hardens, the end surfaces of the optical fiber cores 31a and 31b can be easily optically coupled to each other.

  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 resin bag 5 filled with the uncured refractive index matching resin sr is accommodated in the heat shrinkable tube 2, the optical fiber cores 31a, 31a, 31b can be connected.

  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.

  In addition, since the refractive index matching resin sr used in the optical connector 1 has the same refractive index after curing as that of the core 32, the fiber is cut as when the optical fiber cores 31a and 31b are cut with a general cutting tool. Even if the surface is rough (see FIG. 2B), the cured refractive index matching resin r can be aligned with the cores of the optical fiber cores 31a and 31b. That is, the cured refractive index matching resin r serves as both a matching agent and an adhesive.

  In the above-described embodiment, the example in which the resin bag 5 is accommodated in the heat-shrinkable tube 2 has been described. However, by accommodating a resin tube formed of an uncured refractive index matching resin sr, the resin is not cured in the heat-shrinkable tube 2. The refractive index matching resin sr may be provided.

  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 break through the resin bag 5 by contraction of the heat shrinkable tube 2 may be formed in the vicinity of the resin supply hole 4 on the outer periphery of the core wire insertion tube 3.

  In the above-described embodiment, the uncured refractive index matching resin sr filled in the resin bag 5 has an amount that fills almost the entire volume in the heat-shrinkable tube 2 after shrinkage. It may be a little larger than the total volume. In this case, the surplus refractive index matching resin r overflowing from both ends of the heat-shrinkable tube 2 after shrinkage bonds the heat-shrinkable tube 2 after shrinkage and the optical fiber cores 31a and 31b 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, after removing and cleaning the portion of the coating layer 35 serving as the terminal portion of the butt connection portion of the optical fiber core wire 31, cutting with scissors, the cut optical fiber core wires 31, The connection portion 21 of the optical fiber core wire was manufactured by connecting via the optical connector of FIG. Table 1 shows the connection loss at this time. The same connection was made five times, and the optical fiber 34 was cut with scissors each time.

  The optical fiber 34 uses a normal SMF (single mode optical fiber), the light source 42 is a stabilized light source having a wavelength of 1.55 μm (LD-MG923A: manufactured by Anritsu), and the power meter as the optical power detector 43 is (AQ2140). : Manufactured by Ando Electric Co., Ltd.). 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.

  As shown in Table 1, the connection loss was 0.10 to 0.29 dB, which was 0.20 dB on average. 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. In addition, it is understood that the refractive index matching resin 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.

  As described above, according to the present invention, when the optical fiber 34 is connected, it is not necessary to perform a cutting operation or a polishing operation using a dedicated tool such as a fiber cutter, thereby reducing time, cost, labor, and the like. 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

1 Optical connector 2 Heat shrinkable tube 3 Core wire insertion tube 4 Resin supply hole sr Uncured refractive index matching resin

Claims (6)

  An optical connector for optically connecting end faces of optical fiber core wires covering the outer periphery of an optical fiber comprising a core and a clad, wherein the optical fiber core is provided in the heat shrink tube and the heat shrink tube. A core insertion tube that inserts and matches the end face of the wire, an uncured refractive index matching resin provided between the heat-shrinkable tube and the core insertion tube, and formed in the core insertion tube, An optical connector comprising: a resin supply hole for supplying uncured refractive index matching resin.   The optical connector according to claim 1, wherein a resin bag filled with the uncured refractive index matching resin or a resin tube formed of the uncured refractive index matching resin is accommodated in the heat shrinkable tube.   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.   The optical connector according to claim 1, wherein the refractive index matching resin has a refractive index after curing that is equivalent to a refractive index of the core.   The optical connector according to claim 1, wherein the refractive index matching resin is a thermosetting resin or an ultraviolet curable resin.

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