JPH02264210A - Multiple coated optical fiber - Google Patents

Abstract

PURPOSE:To obtain the multiple coated optical fibers having an excellent crosstalk characteristic by providing opaque layers on the outside of the clads of optical fibers. CONSTITUTION:An optical fiber assemblage formed by aggregating plural pieces of the optical fibers 1 which have the cores and clads and are provided with the opaque layers 1c consisting of, for example, amorphous carbon layers, etc., on the outer side of the fibers is provided with an integral coating 2 consisting of, for example, a UV curing type resin, thermosetting resin or thermoplastic resin, etc. Further, a protective coating 3 consisting of the UV curing type resin, thermosetting resin or thermoplastic resin, etc., is provided thereon at need. For example, a crystalline carbon layer, TiC layer, BN layer, Si3N4 layer, etc., are applicable in addition to the amorphous carbon layer as the opaque layers 1c. The multiple coated optical fibers which do not allow light to leak to the adjacent optical fibers 1 in spite of application of a bending thereto, i.e., have the excellent crosstalk characteristic are obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a multi-optical fiber core in which a plurality of optical fibers are assembled and coated with a bundle.

[Prior art]

Traditionally, optical fiber transmission density (space factor)
For example, as shown in FIG. 3, a plurality of optical fibers 1 each having a core 1a and a cladding 1b provided on the core 1a are bundled together and coated with a bulk coating 2 made of plastic. Accordingly, what is known as a so-called multi-optical fiber core, which is further provided with a protective coating 3, is known.

By the way, in the multi-optical fiber coated wire as shown in FIG. 3, since the crands 1b of each optical fiber 1 are in direct contact with each other, when this multi-optical fiber coated wire is bent, the transmitted light is There is a problem in that a part of the light leaks into the adjacent optical fiber 1, deteriorating so-called crosstalk characteristics.

[Purpose of the invention]

In view of the above problems, an object of the present invention is to provide a multi-optical fiber core with excellent crosstalk characteristics.

[Structure of the invention]

In order to achieve the above object, the present invention provides a multi-optic fiber core wire in which a plurality of optical fibers each having a core and a craft are collectively coated with plastic, in which the optical fibers are opaque to the outside of the cladding. It is characterized by having a layer.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. As shown in this figure, the multi-optical fiber core of the present invention has a thickness of, for example, 500 to A collective coating 2 made of, for example, an ultraviolet curable resin, a thermosetting resin, or a thermoplastic resin is applied to an optical fiber assembly in which a plurality of optical fibers each having an opaque layer 1c such as an amorphous carbon layer of about 1,000 layers are assembled. Further, if necessary, a protective coating 3 made of ultraviolet curable resin, thermosetting resin, thermoplastic resin, etc. is provided thereon.

In addition to the amorphous carbon layer, the opaque layer 1c may be, for example, a crystalline carbon layer, or may include a Ti0 layer, BNN, Si3N4 layer, etc.

Next, FIG. 2 shows an example of a method for manufacturing a multi-optical fiber core according to the present invention.

As shown in FIG. 2, for example, a desired number of single-mode optical fiber preforms 5 <5101-GeOz core/5fOt cladding with Δ゛0.3%, n-c-1.2 μm) is prepared, and this are introduced into the drawing furnace 6 and drawn simultaneously so that the outer diameter of each optical fiber becomes, for example, 125 Bna. These are led to a reaction furnace 7 for forming an opaque layer 1c provided directly below the drawing furnace, and an opaque layer 1c having a thickness of about 500 layers is formed around the outer periphery of each optical fiber 1. Here, when the opaque layer 1c is an amorphous carbon layer, a hydrocarbon such as C211□ is supplied together with helium He, which is an inert gas, into the reactor 7, and this is heated to form an amorphous carbon layer. form a layer.

That is, it is a method usually called CVD method (chemical vapor deposition method).

Next, after forming the opaque layer 1c on the outside of the crand 1b of each optical fiber 1 in this manner, these are guided by the guide roll 8 and brought together.

Thereafter, the aggregate is passed through a coating device 8 to form a bulk coating 2 having an outer diameter of 320 μm, and a protective coating 3 having an outer diameter of 400 μm is further formed by the coating device 10, and then taken out. This is taken up by l1all and finally wound up by a winder (not shown). In the figure, if the plastic to be coated by the coating device 9.11 is an ultraviolet curable resin, reference numerals 12 and I3 indicate an ultraviolet irradiation furnace,
For thermosetting resins, this refers to a curing furnace consisting of a heating furnace.

In this way, a multi-optical fiber core as shown in FIG. 1 was obtained.

By the way, the crosstalk characteristics of the thus obtained multi-optical fiber core of the present invention and the conventional multi-optical fiber core shown in FIG. 3 were compared. The comparison method is to bend both multi-optic fibers along a mandrel with a diameter of 50+ sm, and measure the amount of light leaking from the optical fiber that is passing light to the optical fiber that is not passing light. .

As a result of this measurement, in the case of conventional multi-optical fiber cores,
The amount of leakage was about -60 dB, but in the case of the present invention, it was less than -70 dB, and almost no leakage was observed.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to obtain a multi-optical fiber core that does not leak light to adjacent optical fibers even when bent, that is, has excellent crosstalk characteristics.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the multi-optical fiber core of the present invention, FIG. 2 is a schematic diagram showing an example of a method for manufacturing the multi-optic fiber core of the present invention, and FIG. 3 is a conventional 1 shows a cross-sectional view of a multi-optical fiber core. 18~core 1b~clad 1~optical fiber 10~
Opaque layer 2 - Bracket coating 3 - Protective coating 5 - Optical fiber base material 6 - Drawing furnace 7 - Reactor 9, lO - Coating device Patent applicant Furukawa Electric Co., Ltd.

Claims (1)

[Claims] A collection of multiple optical fibers having a core and cladding,
What is claimed is: 1. A multi-optical fiber coated wire comprising a plastic coating, wherein the optical fiber has an opaque layer on the outside of the cladding.