JPH10197760A - Photocoupling component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To unnecessitate high-accuracy dimension finish by specifying the ratio of total sum in the area of respective cores and the number of cores occupying the cross sectional area of multicore plastic optical fiber. SOLUTION: Concerning a photocoupling component made of resin to be mounted at a short gap from 0.5mm to 30mm, the multicore plastic optical fiber is provided with plural core fibers composed of transparent core resin with high refraction factor by surrounding these fibers with sheath resin having a refraction factor lower than that of the resin, and collecting them into one, the ratio of total sum in the area of respective cores occupying the cross-sectional area of that multicore plastic optical fiber is set from 40% to 90% and the number of respective cores is set more than seven. In this case, since a lot of core wires are parallelly arranged in order for using the multicore plastic optical fiber, there is no problem even when securing the cross section of multicore plastic optical fiber sufficiently larger than the light emitting or receiving end face on the opposite side to be coupled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical coupling component for coupling a short gap in an optical transmission line. Specifically, a short length of about 0.5 mm to 30 mm, such as between an optical fiber terminal and an optical fiber terminal, or between a light emitting element and an optical fiber terminal, or between a light receiving element and an optical fiber terminal. The present invention relates to a resin optical coupling component to be mounted in a gap.

[0002]

2. Description of the Related Art Conventionally, between a light emitting element and an optical fiber terminal,
Alternatively, as an optical coupling component for coupling a gap between a light receiving element and an optical fiber terminal, or between an optical fiber terminal and an optical fiber terminal, a short fiber of an optical fiber having a single core and a sheath was used. .

[0003]

However, in the optical coupling component using a single-core optical fiber that couples a gap according to the prior art, there is a problem that the loss is large unless the mating end surface and the end surface of the optical coupling component are completely aligned. Yes, high-precision dimensional finishing was required to perform centering within very short bond lengths.

[0004]

SUMMARY OF THE INVENTION The present invention is an optical coupling component which makes this coupling easier. That is, the present invention
In a resin-made optical coupling component, which is installed in a short gap having a length of about 0.5 mm to 30 mm, a plurality of core fibers made of a transparent core resin having a high refractive index, and the circumference thereof are determined by the refractive index of the resin. Is also surrounded by a sheath resin having a low refractive index,
A multi-core plastic optical fiber obtained by combining them, wherein the ratio of the total area of the individual cores to the cross-sectional area of the multi-core plastic optical fiber is 40% to 98%, and the number of individual cores is An optical coupling part comprising a multi-core plastic optical fiber, wherein the number is seven or more.

A primary feature of the present invention is that a multi-core plastic optical fiber is used as an optical coupling component. The multi-core plastic optical fiber is used because a large number of core wires are arranged so as to be aligned in parallel, so that the cross-section of the multi-core plastic optical fiber is sufficiently larger than the light emitting end face or light receiving end face of the mating partner. No problem arises. In other words, when a single-core optical fiber is used as a coupling component, if the diameter of the coupling component fiber is too large compared to the light receiving surface, the light that has been relayed through the coupling component protrudes from the coupling component, and only a part of the light can be received.
The same may occur in the case of coupling from a fiber, and it is very important that the diameter of the coupling member before and after the single-core fiber diameter in the coupling component be exactly the same,
It is also important to be united. On the other hand, when using a multi-core plastic optical fiber for the coupling component,
The diameter can be relatively large compared to the fiber or element to be coupled back and forth, and since it is composed of many cores, the light entering the optical coupling component is the area of the coupling partner fiber or light emitting element. Can be accepted correspondingly. Here, there is a great effect that an error of the axis deviation of the optical coupling component is allowed. When a single-core fiber is used, the ferrule for centering needs to be manufactured with particularly high precision.On the other hand, a multi-core plastic optical fiber has no danger of axial misalignment. There is no need to use special ferrules. A multi-core plastic optical fiber used for an optical coupling component requires at least seven cores. When the number is small, uneven bonding due to the arrangement occurs.
00.

Various transparent resins can be used as the resin constituting the core of the multi-core plastic optical fiber. Preferred resins are methyl methacrylate resins. For example, methyl methacrylate homopolymer or copolymer, copolymerizable components include acrylates such as methyl acrylate, ethyl acrylate, n-butyl acrylate, ethyl methacrylate, propyl methacrylate, and methacryl. Examples include methacrylic esters such as cyclohexyl acid, maleimides, acrylic acid, methacrylic acid, maleic anhydride, and styrene. One or more of these can be appropriately selected and copolymerized. Other preferable resins include a styrene resin, a polycarbonate resin, and an amorphous polyolefin resin. On the other hand, as the sheath resin, a resin known as a single core plastic sheath material having these resins as a core can be selected. In particular, the sheath resin in which the core is a methyl methacrylate resin is described in detail. The sheath resin is preferably a vinylidene fluoride resin, which is well compatible with the methyl methacrylate resin. The reason is that the individual cores and the sheaths are completely compatible and adhere to each other, so that some of the cores do not pop out and a uniform fiber end face can be maintained. As such a vinylidene fluoride-based resin, a copolymer of vinylidene fluoride and hexafluoroacetone, or a terpolymer of ternary or more obtained by adding trifluoroethylene or tetrafluoroethylene to these binary components, is used. Very preferred. Further, a copolymer of vinylidene fluoride and hexafluoropropene, or a ternary or more copolymer obtained by adding trifluoroethylene or tetrafluoroethylene to these binary components,
Further, a binary copolymer of vinylidene fluoride and tetrafluoroethylene, a binary copolymer of vinylidene fluoride and trifluoroethylene, and the like. Further, a mixture of such a vinylidene fluoride resin and a methyl methacrylate resin or an ethyl methacrylate resin is also a preferable sheath resin.

The multi-core plastic optical fiber used in the present invention is more preferably a multi-core plastic optical fiber comprising a core resin and a sheath resin in which a number of core islands are scattered in the sea of the sheath. A multi-core plastic optical fiber in which a core and an island in which a sheath resin concentrically surrounds the core is scattered in the sea of the third resin can also be applied. However, the former is preferred since this reduces the area of the core. In this description, for simplicity, a multi-core plastic optical fiber composed of a core island and a sheath sea will be mainly described. The ratio of the sum of the areas of all the cores to the cross-sectional area of the bare multi-core optical fiber is preferably 40% to 98%. In particular, in order to reduce the coupling loss, the area ratio of the core is preferably large, and more preferably 80% to 95%.

In the optical coupling part of the present invention, a bare wire of a multi-core plastic optical fiber can be used as it is,
In some cases, the bare wire may be covered with a hard resin ferrule or a metal ferrule.
Hereinafter, an embodiment will be described.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION

[0010]

EXAMPLE 1 A core resin is a multi-core plastic optical fiber comprising a homopolymer of methyl methacrylate and a sheath resin comprising a copolymer of 80 mol% of vinylidene fluoride and 20 mol% of tetrafluoroethylene. The number of cores is 3,500. A bare multi-core plastic optical fiber having a core area ratio of 90% of the fiber cross-sectional area and a fiber diameter of 2.0 mm was used. This bare wire was cut into a length of 10 mm, and the end face was polished to obtain an optical coupling component. On the other hand, the coupling loss of this optical coupling component was measured using a plastic optical fiber tester HAKTRONICS PHOTOM 205 equipped with a 650n LED and a photodiode. First, 1
With reference to the optical power obtained by coupling both ends of a plastic optical fiber having a length of 0 m to a plastic optical fiber tester, a coupling loss was measured when an optical coupling component was disposed at a position 5 m from the plastic optical fiber. . The end of the plastic optical fiber at the point of 5 m is fixed to a connector having an outer diameter of 3 mmφ and having a hole of 1.1 mm at the center with an adhesive as shown in FIG. Used after polishing. The coupling between the optical coupling component and the plastic optical fiber cables at both ends was fixed by an optical coupling holder (2 in FIG. 1), and the change in optical power was measured. As a result, the loss was 1.2 dB. I repeated the work of setting this optical coupling component,
It was found that the optical coupling loss was within a fluctuation range of 0.1 dB and was stable.

[Brief description of the drawings]

FIG. 1 is a diagram showing a coupling example of an optical coupling component of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Connector 2 Optical coupling component holder 3 Multi-core plastic optical fiber optical coupling component 4 Single core plastic optical fiber bare wire 5 Jacket

Claims (2)

[Claims] 1. A resin optical coupling part to be mounted in a short gap having a length of about 0.5 mm to 30 mm, wherein a plurality of core fibers made of a transparent core resin having a high refractive index and the resin surrounding the core fiber are made of the resin. A multi-core plastic optical fiber surrounded by a sheath resin having a refractive index lower than the refractive index of the multi-core plastic optical fiber, and the total area of the individual cores occupying the cross-sectional area of the multi-core plastic optical fiber. 40% to 9%
8%, and the number of individual cores is 7 or more. An optical coupling component comprising a multi-core plastic optical fiber. 2. The optical coupling component according to claim 1, wherein a cross section of the optical coupling component is equal to or wider than an optical fiber cross section coupled before and after the coupling component.