JP3150752B2 - Optical discrimination structure of optical transmission line - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical identification structure for identifying the number (address) of an optical transmission line such as an optical fiber or an optical waveguide by light.

[0002]

2. Description of the Related Art As a conventional optical identification structure of an optical transmission line,
For example, there is one described in IEICE (1991) Autumn Conference Lecture Book B-591. Here, optical fibers having different relative refractive indices of a core and a clad are connected in tandem, and this is used as an optical identification structure, which is measured by OTDR for identification. According to this, the number of the optical fiber can be recognized by associating the optical identification structure with the binary code.

[0003]

However, the above-described optical identification structure can be applied to identification of a long optical fiber line.
It is difficult to use to identify individual components such as optical couplers. That is, it has been difficult to discriminate within a range of several centimeters.

[0004] In addition, in order to realize an optical discrimination structure by connecting optical fibers having different structural parameters, not only is the manufacturing process difficult, but also the connection loss is increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide an optical discriminating structure which can be made compact in structure and can reduce the connection loss of light. It can be realized not only by a fiber but also by an optical waveguide device.

[0006]

According to the present invention, there is provided a light discrimination structure for an optical transmission line, wherein a pulse light incident on the optical transmission line is reflected by an identification unit to identify the optical transmission line. The optical transmission path of the identification unit is constituted by a core region and a cladding region around the core region, a part of the cladding region is removed in a predetermined direction toward the core region to form a groove, and the depth or shape of the groove is It is characterized in that it is a parameter corresponding to optical identification.

[0007]

According to the present invention, by forming a groove in a cladding region of an optical transmission line, a reflection structure of pulse light for identification can be obtained. Can be identified.

If the depth of the groove does not reach the core region, light loss can be suppressed. Further, by performing the reflection increasing process, useless light reflection can be eliminated.

On the other hand, by changing the shape of the groove or changing the depth, various reflected lights can be obtained, and the identification performance is improved.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Some embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a perspective view of an embodiment showing a state in which the optical discriminating structure is realized by an optical fiber in a partial cross section. As shown in the figure, the optical fiber 1 includes a core 11 at the center and a clad 12 around the core, and the clad 12 is formed with a groove 2 having a triangular cross section.

The grooves 2 are formed at five locations corresponding to the code (number) "1011110" indicated by the optical identification structure. Since the groove 2 does not reach the core 11, light loss is reduced. That is, the optical fiber 1
Is generally Gaussian and concentrated in the core 11, so that the grooves 2 in the cladding 12
Does not significantly increase light loss.

In addition, since a certain level of light is distributed in the cladding 12 although the light intensity is low, the backscattering coefficient is changed by changing the refractive index by the groove 2 and the reflected light is detected by the OTDR. Then, optical identification of the optical transmission path is possible.

[0014] Specifically, for example, the aforementioned conference proceedings C-
As shown in FIG. 259, since a spatial resolution of about 100 μm is obtained by OTDR, even if a 12-bit optical fiber cable (4000 core identification) is used, 2 m
An optical discrimination structure having a length of about m can be used, and ultra-miniaturization is possible.

Next, a manufacturing process of the optical discrimination structure of the tape-shaped optical fiber according to the embodiment will be described with reference to FIGS.

First, as shown in an exploded perspective view of FIG. 2, a tape optical fiber 3 from which a coating 31 has been partially removed is prepared, and the tape optical fiber 3 is formed on a mounting table 41 at the center of a substrate 4.
It is set in the fiber groove 42 of a letter shape. Then, the holding plate 5 is set on the exposed optical fiber 1 of the tape optical fiber 3. FIG. 3 shows this state in a side view.
(A).

Here, various materials can be used for the substrate 4 and the holding plate 5, but a silicon (Si) plate is preferable in consideration of easiness of processing. Further, in a state where the optical fiber 1 is held between the substrate 4 and the holding plate 5, these may be fixed with an ultraviolet curing resin or the like.

Next, as shown in FIG. 3B, grinding is performed with a diamond blade. That is, a cut is made in the holding plate 5 and the cladding region of the optical fiber 1 is further ground to form a groove as shown in FIG. Here, if the feed pitch and feed amount of the diamond blade are programmed in advance in the controller, a groove portion corresponding to the identification code can be automatically formed. Regarding the processing accuracy, about ± 5 μm can be easily realized.
Processing at a pitch of about 0 μm has no problem.

Next, in the groove formed as described above, FIG.
As shown in (c), a reflection enhancer 6 having a different refractive index from that of the optical fiber 1 is injected. This material preferably has an adhesive property in consideration of mechanical reliability. Thereafter, the light discrimination structure is inserted into the heat-shrinkable tube 7 and subjected to a shrinking process. As a result, a structure like the partially crushed cross section in FIG. 3C is obtained.

Next, a specific example of trial production by the present inventors will be described.

First, the coating of the middle part of the 8-core tape fiber was removed over about 10 mm, fixed to the substrate, and then precision-adjusted in units of 1 μm with a diamond blade having a thickness of 30 μm and a 60 ° tip, Groove processing for 12 bits was performed at a pitch of 200 μm. After the processing, a high-refractive-index ultraviolet curable resin was injected into the groove, and after curing, the whole was reinforced with a heat-shrinkable tube. The substrate was made of a Si material.

When the finished product was tested by OTDR, the reflection of the grooved portion showed 40 to 50 dB, and the reflection of the portion where the groove was not formed showed 60 dB or more. Was. Note that the total loss was 0.1 dB or less, which was a level with no problem as a loss. The waveform observed by the OTDR in this case is, for example, as shown in FIG.

Various modifications and applications of the present invention are possible.

For example, the shape of the groove in the cladding region is not particularly limited to the embodiment.
(B). Also, the depth of the groove may be partly deep and partly shallow, so that the number of identifiable combinations increases.

Further, in a housing 82 in which an optical element 81 such as an optical connector, an optical coupler or an optical filter is mounted,
The optical identification structure 83 of the embodiment may be integrated. FIG. 6 shows an optical element 81 and an optical discriminating structure 83 connected to an optical fiber 84.
Are connected in series and incorporated in the housing 82. The optical connection with the outside is realized by the connector 85.

Further, as shown in FIG. 7, an optical identification structure may be realized in an optical waveguide device. As shown in the figure, a waveguide 87 is formed on a substrate 86 of LiNbO ₃ or the like by Ti diffusion or the like. Then, the substrate 86 near the waveguide 87 is processed by etching to form the groove 2 as a light identification structure.

[0027]

As described above in detail, in the optical discrimination structure of the optical transmission line according to the present invention, by forming a groove in the cladding region of the optical transmission line, a reflection structure of pulse light for identification can be obtained. By coding this, identification by reflected light using OTDR becomes possible. Further, if the depth of the groove does not reach the core region, the optical loss in optical communication can be suppressed low. Further, by performing the reflection increasing process with an adhesive, useless light reflection can be eliminated while increasing the mechanical strength.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an optical identification structure of an optical fiber according to an embodiment.

FIG. 2 is an exploded perspective view showing a manufacturing process.

FIG. 3 is a side view showing a manufacturing process.

FIG. 4 is a detection waveform diagram of OTDR.

FIG. 5 is a side view of a light discrimination structure of an optical fiber according to a modification.

FIG. 6 is a diagram showing an example in which the optical element is incorporated in a housing.

FIG. 7 is a perspective view of an optical identification structure realized by an optical waveguide device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical fiber, 11 ... Core, 12 ... Clad, 2 ...
Groove, 3: Tape optical fiber, 4: Substrate, 42: Fiber groove, 5: Pressing plate, 87: Waveguide.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Tadashi Haibara 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (56) References Proc. Of IEICE Conference, 1991 [Autumn 4 (1991) p. 4.51 (58) Field surveyed (Int. Cl. ⁷ , DB name) G02B 6/00 G01M 11/00

Claims (3)

(57) [Claims] In an optical discrimination structure of an optical transmission line for recognizing an optical transmission line by reflecting a pulse light incident on the optical transmission line by an identification unit, the optical transmission line of the identification unit is defined as a core region. A part of the cladding region is removed in a direction of the core region in a predetermined shape to form a groove, and a depth or a shape of the groove is a parameter corresponding to light identification. An optical discrimination structure for an optical transmission line. 2. The optical identification structure of an optical transmission line according to claim 1, wherein said groove has a depth that does not reach said core region. 3. The optical discrimination structure of an optical transmission line according to claim 1, wherein the groove is subjected to a process of increasing a reflectance of the pulse light.