JPS62175706A - Contrasting method for tape type optical fiber core - Google Patents

Abstract

PURPOSE:To make more exact contrasting of cores by constituting a bending jig of a member which does not substantially reflect the light leaking from a bent part. CONSTITUTION:The bending jig 2' is constituted of a material having a refractive index of the value approximately the same as the refractive index of a coating material 1f of a fiber tape 1, for example, transparent polyacrylate (acrylic resin). The light leaking from the bent part of the core and heading toward the bottom wall surface 2a' of the bending jig 2' is not reflected by the bottom wall surface 2a' and transmits the inside of the bending jig 2' if the bending jig 2' is constituted of such acrylic resin material. The light transmitted therethrough in the above-mentioned manner is not made incident on a photodetector 5 via a slit 4 and therefore, a crosstalk is eliminated. The entire part of the bending jig 2' is preferably subjected to light shielding in the case of using the transparent bending jig 2'. The contrasting of the core is thereby surely executed.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention involves wrapping a tape-shaped optical fiber cable consisting of a plurality of core wires around a bending jig and bending the cable, thereby reducing the amount of light leaking from the bent portion of the core wires. The present invention relates to a tape-type optical fiber core comparison method for detecting and comparing core fibers.

(Prior Art) When a fiber tape composed of a plurality of core wires is used for optical communication, not all of the core wires are used and a portion of the core wires is often left as a spare.

After laying the fiber tape, one of the remaining core wires is found, cut out from the tape, and connected to an optical element such as an optical multiplexer or optical demultiplexer to create a spare core wire. You may want to use it.

In such a case, first, in order to find a spare core, the fiber tape is bent at a predetermined bending radius, the light propagating through each core is leaked from the core, and the amount of leaked light is detected. Spare core wires are searched for by clearly distinguishing and comparing the core wires that propagate light and the core wires that do not propagate light.

3 to 5 show a fiber comparison device applied to such a fiber comparison method, in which a fiber tape 1 has, for example, five fibers 1a to 1e arranged in parallel in a row, and these fibers are It is an optical fiber cable that extends in a tape shape and has a core wire coated with a transparent UV resin material If. This fiber tape l is placed along one side wall 2b of the bending jig 2, which has a semi-cylindrical bottom wall 2a and a rectangular cross section, and from the bottom wall 2a to the other side wall 2C, with each core mla to 1e in close contact with the wall surface. It's completely wrapped around it. A light shielding plate 3 having a predetermined thickness t (FIG. 5), which extends in the longitudinal direction (X direction in the drawing) of the bottom wall 2a of the bending jig 2 and has a semicircular arc cross section, is attached to the bending jig 2. bottom wall 2
a is surrounded with the fiber tape 1 interposed therebetween and in close contact with the fiber tape l. Light shielding plate 3
is movable in the longitudinal direction with respect to the bending jig 2 (in the X direction perpendicular to the core wires 1a-1e in FIGS. 3 and 5), and is located approximately in the longitudinal center of the light shielding plate 3 and at the bottom A predetermined slit width d (Fig. 5) and a predetermined length l (Fig. 4)
A slit 4 is formed.

A light receiving element 5 is disposed below the slit 4 and at a position facing the slit 4, which moves with the movement of the light shielding plate 3.

Using such a fiber comparison device, the light receiving element 5 is sequentially moved together with the light shielding plate 3 from the fiber 1a side to the fiber le side, and the fiber 1
By measuring the amount of light leaking from a to 1e through the slit 4, it is possible to identify the spare fiber from the measured light amount at each fiber position.

(Problems to be Solved by the Invention) In the above-mentioned fiber comparison device, the bending jig 2 has conventionally been made of aluminum, the surface of which has been treated with black alumite. The light is reflected by the bottom wall surface 2a of the bending jig 2, and this reflected light is received by the light receiving element 5 through the slit 2, resulting in a so-called crosstalk phenomenon. Now, the core wire diameter is 0.3 μm, and the bottom wall 2 of the bending jig 2
The radius of curvature of a, that is, the bending radius of the fiber tape 1 is 4-
The plate thickness of the bending jig 2, that is, the slit thickness t, is 0.51.
, the slit width d is set to 0.3N, the slit 4 and the light receiving element 5 are moved to a position aligned with the axis of the third center f11c, as shown in FIG. When the amount of leakage light of the reference light having the same amount of light that was incident on the wire 1b and the third core IC was measured, the difference between the two measured amounts of light was about 5 dB. Also, only the slit width d is set to 0.
When the amount of leaked light was measured under the same conditions as above except that the amount of light was changed to 1+s, the difference in light amount was about 7 dB.

In the above measurements, reference light with the same amount of light was incident on each fiber, but in reality, the difference in light amount between the optical signals propagating through each fiber of fiber tape used in the field is usually 10.
dB, so if the light intensity difference between the optical signals propagating through each fiber is about 1 odB, as in the measurement example above, if the leakage light amount difference is less than 10 dB, the comparison of the spare fiber is not possible. In order to make it possible to compare the spare fibers, it is desirable that the difference in the amount of leakage light measured taking into account the difference in the amount of light of the optical signal propagating through each fiber is small (both are preferably 10 dB or more). This requires preventing the reflection of leaked light on the bottom wall surface 2a of the bending jig 2.

The present invention has been made in response to such a need, and an object of the present invention is to provide a method for comparing ribbons of tape-shaped optical fibers, which allows more accurate comparison of the ribbons.

(Means for Solving the Problems) In order to achieve the above-mentioned object, according to the present invention, a tape-shaped optical fiber cable composed of a plurality of core wires is wound around a bending jig and bent. In the fiber comparison method of detecting the amount of light leaking from the bent portion and comparing the fiber conductors, the bending jig is tape-shaped, characterized in that the bending jig is made of a member that does not substantially reflect the light leaking from the bent portion. An optical fiber core comparison method is provided.

(Function) Light leaking from the bent portion of the core wire and directed toward the surface of the bending jig is absorbed by the bending jig made of a member that does not substantially reflect this light, and is reflected by the bending jig at the core. This eliminates the effects of light.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

The fiber comparison device that carries out the method of the present invention differs from the conventional device shown in FIGS. 3 to 5 only in the material of the bending jig or the surface treatment method of the bottom wall of the bending jig, and in the shape and shape of the bending jig. There are no changes in the shape or function of other components, so parts that are common to the conventional device are designated by the same reference numerals.
The explanation will be omitted.

FIG. 1 shows a first embodiment of the apparatus for carrying out the method of the present invention, in which the bending jig 2° is made of a material having a refractive index approximately the same as that of the covering material 1r of the fiber tape 1, such as transparent polyester. Composed of acrylate (acrylic resin). When the bending jig 2' is made of such an acrylic resin material, light leaking from the bent portion of the core wire and directed toward the bottom wall surface 2a'' of the bending jig 2° is not reflected by the bottom wall surface 2a. The light transmitted through the bending jig 2' does not enter the light receiving element 5 through the slit 4, thereby eliminating the crosstalk phenomenon.

In addition, when using the transparent bending jig 2° shown in FIG. It is desirable that the entire bending jig 2' be shielded from light, since there is a risk that the light may enter the element 5 and have an adverse effect on the fiber alignment. Moreover, in reality, the space between the bottom wall surface 2 a l of the bending jig 21 and the fiber tape 1 is filled with optical oil 10 having approximately the same refractive index as the coating material lr.

FIG. 2 shows a second embodiment of the apparatus for carrying out the method of the present invention, in which the bottom wall surface 23'' of the bending jig 2'' is coated with a non-reflection absorbing layer 12. The coating of this non-reflection absorbing layer 12 is applied to the bottom wall surface 2 of the steel bending jig 2''.
This is realized by applying black chrome plating to f, for example.

In the case of the second embodiment as well, light leaking from the bent portion of the core wire and directed toward the bottom wall surface 2a' of the bending jig 2' is absorbed by the non-reflection absorption layer 12 without being reflected by the bottom wall surface 2a. Since the absorbed light does not enter the light receiving element 5 through the slit 4, the crosstalk phenomenon is also eliminated in this embodiment.

(Effects of the Invention) As detailed above, according to the tape-type optical fiber core comparison method of the present invention, the bending jig is made of a member that does not substantially reflect light leaking from the bent portion of the core. Therefore, it is possible to suppress so-called crosstalk to a minimum in fiber tape core comparison, and thereby the core wire comparison can be performed reliably.

[Brief explanation of drawings]

FIG. 1 shows a first embodiment of a fiber matching device for carrying out the method of the present invention, and is a partial sectional view showing the bending jig in detail, and FIG. 2 shows a first embodiment of the fiber matching device for carrying out the method of the present invention. A partial sectional view showing the second embodiment and showing the bending jig part in detail, FIG. 3 is a partial cross-sectional perspective view of a conventional fiber matching device, and FIG. 4 is a partial sectional view of the conventional fiber matching device. Partial cross-sectional side view, Figure 5 is V-V of Figure 4.
FIG. l...Fiber tape, 2', 2"...bending jig,
3... Light shielding plate, 4... Slit, 5... Light receiving element, 12... Non-reflection absorption layer. Applicant Furukawa Electric Co., Ltd. Representative Patent Attorney Kanji Nagato

Claims (1)

[Claims] 1. A tape-shaped optical fiber cable composed of a plurality of core wires is wrapped around a bending jig and bent, and the core wires are compared by detecting the amount of light leaking from the bent portion of the core wires. In the line comparison method, the bending jig is comprised of a member that does not substantially reflect light leaking from the bent portion. 2. The tape-shaped optical fiber core comparison method according to claim 1, wherein the member of the bending jig is substantially transparent to light leaking from the bending portion. 3. The tape shape according to claim 1, characterized in that a non-reflective absorption layer is formed on the surface of the member of the bending jig, which absorbs light leaking from the bending part and does not substantially reflect it. Optical fiber core comparison method.