JPH0536762B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an optical connector that requires highly accurate positioning, typically for single mode fiber, and a method for manufacturing the same ferrule.

[Prior Art and Problems] FIG. 8 shows a cross-sectional view of an example of a conventional optical connector. In the figure, reference numeral 1 indicates a coated optical fiber, and reference numeral 2 indicates a bare optical fiber (glass portion) from which the coating at the tip has been removed. Reference numeral 3 indicates a metal ferrule, 10 indicates its brim, and the metal ferrule 3 has a coated optical fiber core 1.
A large-diameter hole 5' and a fine hole 5 connected thereto are formed through which the bare optical fiber 2 with the coating removed is inserted, and the optical fiber core wire 1 with the coating removed at the tip is formed in the hole. is inserted, the bare optical fiber 2 fits into the fine hole 5, the coated optical fiber core 1 stops at a step in the hole,
The gap formed between the optical fiber core 1 and the holes 5' and 5 is filled with adhesive 4, and the optical fiber core 1 is fixed to the metal ferrule 3. metal ferrule 3
Cut the bare optical fiber 2 that protrudes from the end surface of. By polishing the end face so that it is flush with the end face of the metal ferrule 3, a metal ferrule equipped with an optical fiber for an optical connector is completed.

By the way, in the case of a single-mode fiber connector as an example of a high-precision optical connector, the core diameter of the single-mode fiber is 125 μm while the outer diameter is 125 μm.
Extremely small at 10μm, with excellent positioning accuracy
1μm or less is required. For example, it is difficult to obtain a coupling loss of 1 dB or less unless the eccentricity of the fiber hole diameter with respect to the outer diameter is at most 1 μm or less. Furthermore, even if the eccentricity is suppressed to 1 μm or less, if the core eccentricity with respect to the cladding of a single molded fiber is 1 μm or more, a coupling loss of 1 dB or more will result. For this reason, in metal ferrules equipped with optical fibers as described above, the outer diameter of the ferrule is usually ground around the core of the bare optical fiber, but this processing method is difficult to mass-produce. The drawback is that it is poor in quality and expensive.

[Object of the invention. [Structure] The present invention overcomes the above-mentioned drawbacks and provides a manufacturing method with extremely high production efficiency of an optical connector that requires high precision and a ferrule for the optical connector.

To put it simply, the present invention places a cored optical fiber with a part of the coating removed to expose the bare optical fiber in a mold, and connects two ferrules with the bare optical fiber as a boundary. While molding with mold resin, a hole for a connecting pin for fitting positioning is formed, and the molded ferrule is separated into two ferrules, and during actual optical connection, the separated ferrule is replaced with both ferrules during the previous molding. The optical fibers are configured so that they can be connected while maintaining their mutual positions, and alignment of the cores of the optical fibers during connection is extremely simple.

The present invention will be explained below with reference to embodiments shown in the drawings. In the following figures, the same reference numerals are used for the same parts as in FIG. 8.

FIG. 1A is a longitudinal sectional view of the embodiment, and FIG. 1B is a front view.

17 indicates the entire ferrule. 11 is a metal pipe, 10 is a flange of the ferrule 17, 9 is a hole formed in the flange 10, and the optical fiber core wire 1
Part of the coating is removed to expose the bare optical fiber 2 and inserted into the metal pipe 11,
It is integrally molded with mold resin 8. Therefore, the collar 10 having the hole 9 is integrated with the metal pipe 11, and the inside of the metal pipe 11 is filled with the molding resin 8, and the bare optical fiber 2 is fixed at a fixed position.

The manufacturing of such ferrules will be described in detail later, but at the same time, a pair of ferrules each having an optical fiber molded using the bare optical fiber 2 in common are inserted from both ends of the sleeve 7, fitted together, and then The end surfaces of the ferrules 17 are brought into a state of being joined, and the connecting pin 6 is passed through the hole 9 formed in the collar portion 10 of both the ferrules 17 to perform positioning in the rotational direction, thereby forming an optical connection section.

As shown in FIG. 2 A and B, the optical connection section configured in this way is fixed by applying pressure in the axial direction between the ferrules 17, so the fixing housing 12
have. The fixing housing 12 may be of a type that presses the ferrule 17 in the axial direction, and instead of a type that presses the flange portion 10 with a metal plate spring as shown in the figure, it may be a housing member made of a plurality of parts. There is no problem with this, and the above-described fixing means can also be used in the upper and lower fixing directions of the ferrule 17.

Next, the manufacturing method of the present invention will be explained. Third
The figure is an explanatory diagram for implementing the present invention. Reference numeral 13 denotes a molding mold (top view), which is divided into two parts in the length direction, and has a mold surface capable of molding two ferrules at the same time, as shown in Fig. 1, which has already been explained. It is equipped with The spout, runner, etc. of the mold 13 are not shown.

The coating is removed, and the exposed optical fiber core 2 is inserted into two metal pipes 11.
For example, a fixing member 14 split into two is interposed between the bare wire 2 and the metal pipes 11 , and the end surfaces of both metal pipes 11 are joined to the fixing member 14 . An optical fiber core 1 having a coating connected thereto is located on the central axis of both metal pipes 11, and the remaining part of the optical fiber core 1 is arranged on the mold surface so as to extend outside the mold 13. In order to provide a longitudinal hole 9 in the portion that will become the flange portion 10 in FIG. , a mold resin 8, for example, an epoxy resin, is used for batch molding.

As a result, the collar portion 10 as shown in FIG.
The metal pipe 11 is integrated with the flange part 1 at the same time.
Two optical fiber core wires having a hole 9 at 0, the inside of the metal pipe 11 being filled with molding resin 8 in the same way as the collar 10, and the whole (including the connecting pin 15 for molding) being integrated. A batch molded body of ferrules is obtained.

After that, the collective molded body is taken out from the mold 13, the forming connecting pin 15 is pulled out, and the exposed wire 2 is divided by cutting or the like at the part where the coating is removed, that is, the central part of the collective molded body, and the end face of the bare wire 2 is polished.

As a result, a pair of ferrules used for optical connections are simultaneously made.

In the above manufacturing process, a part of the coated optical fiber core wire 1 is removed and the bare wire 2 is exposed.However, for handling purposes, as shown in FIG. It is also possible to use a cored optical fiber 1 having a fusion splice point 16 in which the bare wires 2 of two optical fibers 1 are fused together by removing the coating at one end and exposing the bare wires 2.

In addition, as shown in Fig. 5 A and B, the metal pipe 11
If a part of the metal pipe, for example, a metal pipe having an uneven or threaded surface on the inner or outer surface, is used, the adhesive area with the mold resin 8 can be increased and separation between the mold resin 8 and the metal pipe 11 can be prevented. I can do it.

Although the above description is directed to a single-core optical fiber, it goes without saying that the present invention can be applied to multi-core optical fibers as shown in FIGS. 6 and 7. Both figures are front views. 5 shown in Figure 6
In the case of a core, the optical fiber core 1 with the coating partially removed
Using a mold similar to the mold 13 described above, the metal pipes 11 are inserted into the metal pipes 11, aligned, and molded together with the mold resin 8. The ferrule thus completed is provided with a hole 9 for rotational positioning.

Regarding the implementation of the present invention according to FIG. 3 above, an explanation has been given of a case in which two metal pipes 11 are molded integrally with the collar portion 10.
The optical fiber core 1 with a part of the coating removed to expose the bare wire 2 is inserted into a metal pipe 11 of an appropriate length, and the optical fiber core 1 is inserted into the metal pipe 11.
It may be molded with mold resin 8 while being supported in the direction along the central axis of 1. in this case,
Needless to say, this can be similarly applied to multi-centered objects.

The integral molded body thus formed is divided by cutting at the metal pipe portion, and the end face of the metal pipe is processed by cutting, and the end face of the bare optical fiber wire is also finished to create an optical connection surface.

In this case as well, in order to accurately match the connection position (rotational direction) of the completed ferrule with the optical fiber, a hole into which the pin fits is provided in the collar of each ferrule during molding. do not have.

Next, the dimensions and shape of an example of the ferrule according to the present invention will be explained. Its shape is approximately as shown in Figure 1, and the outer diameter of the sleeve insertion part of the ferrule is 2.5 mmφ, the flange of the ferrule is square, the thickness of the flange is 6 mm, and the diameter of the hole is 1 mmφ. be. Further, a metal pipe provided with an internal thread serves as an entry point into the sleeve of the ferrule, and a molded resin portion protrudes from the end face of the ferrule. The length of the sleeve fitting portion of this ferrule is approximately 8 mm. The dimensions of the brim are approximately 6.5mm x 4.5mm. The total length of the ferrule is 18mm.

During manufacturing, the single mode fiber core wire was optically monitored and fusion spliced as explained in FIG. 4. The average fusion loss at this time is 0.04 dB. The length of the bare wire portion with the coating removed is approximately 10 mm. As already explained, the optical fiber core wires were passed through metal pipes in advance and set in the molds, and the connecting pins for molding were also set at the same time.

After that, the mold was tightened and molded all at once using an epoxy resin that can be molded under low pressure. Molding pressure 20Kg/
^cm2 , molding temperature is 170℃, and molding time is 5 minutes.

After that, take out the batch molded body from the mold, pull out the molding connecting pin, and
In other words, the fusion splice of the bare wire is sandwiched between the two.
After cutting at several places, the end faces of the bare optical fibers on both end faces of the obtained ferrule were polished. The connecting pins are slightly larger than the connecting pins used in actual optical connections, taking into consideration the molding shrinkage rate. When the obtained ferrules are combined using a sleeve and a connecting pin, the average coupling loss for a total of 20 samples is 0.57 dB, and the maximum
It was 0.87dB.

This value is almost the same as that of a normal multimode fiber connector, and it can be understood that it can be put to practical use. Note that although a split sleeve was used as the sleeve, a precision sleeve without splits may be used.

Further, as described above, although fusion splicing is used as the structure of the sheath removal part (the bare wire part), it is also possible to remove a part of the sheath.

Although the above description has mainly focused on the implementation using a single mode fiber, it is clear that it can also be applied to connectors for other multimode fibers and multi-core optical fibers, which have already been briefly mentioned. [Effects] As explained above, the present invention An optical fiber core wire is inserted into a metal pipe, a common optical fiber is used, and connecting pins for forming are placed in advance to create a mass molded body, which is then cut into ferrules each equipped with an optical fiber. Since a pair of ferrules are made by dividing the ferrule, by fitting the ferrule into the sleeve and passing a connecting pin between the holes in the ferrule, the core of the optical fiber can be inserted into the core at the same position as when molding a common optical fiber. This enables accurate joining of parts. Therefore, there is no need for grinding of the outer diameter of the ferrule centering on the core part as in the conventional method.

In addition, it becomes possible to easily produce pairs of ferrules equipped with optical fibers that require high precision by resin molding, and the molding time can be completed in a short time, significantly improving productivity. , a low-cost optical connector will be realized.

In addition, since the ferrule has a metal pipe on its outer periphery, the yield of the outer diameter (irregularity of the outer diameter) is significantly improved compared to the entire resin molded ferrule, and the bending strength of the ferrule is also improved. It can hold more than 8 kg, and since it is made of metal pipe, it has excellent wear resistance when attaching and detaching.
Even after 1000 connections and disconnections, the variation was less than ±0.2dB, which is an excellent result in terms of coupling reproducibility as a single mode fiber connector.

After fusion splicing the optical fiber core wires and collectively forming (positioning) them, in the process of cutting the mass formed body, the bare wire fixing member is used to set the fusion spliced portion of the bare wires at this position. This has the advantage that the dimensions between the metal pipes are defined, and the fusion spliced portion can be removed by cutting after molding, and does not remain on the ferrule.

If a single metal pipe is used instead of two metal pipes to make a batch molded product, it will be easier to set it into a mold during molding. By using a single metal pipe with a common bare optical fiber wire, we make a batch molded body.
It goes without saying that even if this is cut at a point where the bare optical fiber is common, a pair of ferrules can be obtained that is as effective as using two metal pipes.

[Brief explanation of the drawing]

FIGS. 1A and 1B are a longitudinal sectional view and a front view of an embodiment of the optical connector of the present invention. Figure 2 A,
B shows an example of pressurizing fixation of the optical connector of the present invention by a housing member. FIG. 3 is an explanatory diagram of manufacturing a ferrule including the optical fiber core of the present invention.
FIG. 4 is an explanatory diagram of fusion splicing of bare wires with the coating of the optical fiber core wire removed. Figures 5A and 5B show an example of a metal pipe that is integrated with a ferrule and has an uneven surface formed thereon. FIGS. 6 and 7 show front views of embodiments of the present invention using multi-core optical fibers. FIG. 8 shows an example of a conventional metal ferrule in a longitudinal sectional view. DESCRIPTION OF SYMBOLS 1... Optical fiber core wire (coated part), 2... Optical fiber bare wire (glass part), 6... Connecting pin, 7... Sleeve, 8... Mold resin, 9... Hole part, 10... Flange part, 11... Metal Pipe, 12... Fixing housing, 13... Mold, 14... Optical fiber bare wire fixing member, 15... Connecting pin for molding, 16... Fusion splicing point.

Claims (1)

[Scope of Claims] 1. A metal pipe through which a bare optical fiber core wire with a part of the coating removed is inserted and a connecting pin for molding are set in a mold, and a lump molded body is formed by resin molding. A pair of ferrule metal pipes each having a split optical fiber core wire are passed through the sleeve and fitted together, and the connecting pin is passed through the hole formed in the ferrule collar by the forming connecting pin. An optical connector characterized in that the optical connector is connected by a housing member that applies pressure in the axial direction of the fitted ferrule. 2. The optical connector according to claim 1, wherein the inner and outer surfaces of the metal pipe are partially uneven. 3. A cored optical fiber with a part of the coating removed to form a bare wire is inserted into a metal pipe, and the metal pipe is placed in a mold, and the remaining part of the cored optical fiber is placed outside the mold. At the same time, a connecting pin for molding is arranged in parallel with the metal pipe, and the inside of the metal pipe is also filled with the mold resin, and the two flange parts, the metal pipe, the optical fiber core wire, and the molding A molded body consisting of connecting pins is formed, the molded body is removed from the mold, the connecting pin for molding is pulled out from the brim portion, and the metal pipe is divided at the center to provide a pair of optical fiber cores. A method for manufacturing a ferrule for an optical connector, characterized in that the ferrule is made of a ferrule. 4. The method for manufacturing a ferrule for an optical connector according to claim 3, characterized in that two metal pipes are used. 5. The method of manufacturing a ferrule for an optical connector according to claim 3, characterized in that a single metal pipe is used. 6. Claim No. 6, characterized in that the optical fiber core wire to be inserted into the metal pipe is made by fusion-splicing the bare ends of two optical fiber core wires with one end of which the coating has been removed in advance. A method for manufacturing a ferrule for an optical connector according to any one of Items 3 to 5. 7. A method of manufacturing a ferrule for an optical connector according to claim 6, characterized in that the multi-core optical fiber core wire is inserted into a metal pipe.