JP2635699B2 - Optical fiber connector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a connector for connecting an optical fiber.

[Conventional technology and its problems]

Conventionally, a sleeve having a thin hole into which an optical fiber is inserted at the center is used, an optical fiber to be connected is inserted from both ends into the sleeve, and end faces of both optical fibers are abutted in the sleeve to connect the optical fibers. It is known.

However, in such a connection structure, it is difficult to insert the optical fiber into the narrow hole of the sleeve, and the abutting state of the optical fiber end faces in the sleeve (the presence or absence of a gap, its size, whether foreign matter is caught, etc.) ) Can not be confirmed.

Conventionally, when a plurality of optical fibers of a multi-core optical fiber cable are mechanically connected collectively, a connector body having a plurality of V-grooves formed on an upper surface thereof and a holding plate placed on the connector body are used. It is also known that an optical fiber corresponding to each V-groove of the connector body is placed and the end faces are abutted, and a pressing plate is pressed from above to maintain the connection state (for example, Japanese Utility Model Application Laid-Open No. 54-96651). ).

However, in such a connection structure, when a plurality of optical fibers are respectively butted on the V-grooves and the holding plate is put on, some of the optical fibers may be lifted and the butted state may not be maintained. There is a problem that it is difficult to do. In addition, it is difficult to apply the pressing force of the holding plate evenly to each optical fiber, and there is a problem that the connection state tends to vary due to the optical fibers.

[Means for solving the problem and its operation]

Therefore, the present inventors have developed an optical fiber connector as shown in FIGS. This connector includes a substrate 11, a capillary tube 12, and a protection plate 13.

The substrate 11 is made of plastic, has a capillary mounting groove 14 at the center in the longitudinal direction of the upper surface, optical fiber guide grooves 15a and 15b at both ends, and a coating mounting groove 16 at both ends.
a and 16b are respectively formed. In the illustrated example, the number of the capillary mounting groove 14 and the number of the optical fiber guide grooves 15a and 15b are two, but this number is determined by the number of optical fibers to be connected.

The capillary 12 is made of glass or ceramic, and the substrate 11
Is fixed to the capillary mounting groove 14 by an adhesive or the like,
An opening 17 is formed at the center in the longitudinal direction. The protection plate 13 is made of plastic,
It is fixed over the upper surface of 11. In addition, guides 18 for positioning the protection plate 13 are projected from four corners of the substrate 11.

The connection of the optical fiber by this connector is performed as follows.

The optical fibers 21a and 21b, from which the coating has been removed, are inserted into the capillary tube 12 from both ends, and their end faces are butted at the opening 17. Capillary mounting groove 14 and optical fiber guide groove 15a ・ 1
5b is formed so that the axes of the capillary 12 placed in the capillary mounting groove 14 and the optical fibers 21a and 21b placed in the optical fiber guide grooves 15a and 15b coincide with each other. The insertion of the fibers 21a and 21b can be easily performed by sliding the optical fibers 21a and 21b along the optical fiber guide grooves 15a and 15b. Optical fiber 21a
・ The butting portion of 21b has a refractive index adjuster 22 having viscosity.
Is applied. Also, the optical fiber guide grooves 15a and 15b of the substrate 11
The optical fibers 21a and 21b mounted on the
The coating portions 23a and 23b of the optical fibers mounted on the substrate 16b are fixed to the substrate 11 by the adhesive 24, respectively. In this state, the protective plate 13 is put on the upper surface of the substrate 11, and is fixed to the substrate 11 with an adhesive, a clip, a screw, or the like. This completes the connection.

The newly developed connector has the advantage that optical fibers can be easily and accurately connected.However, according to various tests conducted after the connection, it has been found that when exposed to high temperatures, It has been found that a problematic increase in transmission loss may occur. Figure 16 shows an example of the transmission loss measurement results.

In order to investigate the cause, when the optical fiber connection was heated to a high temperature and observed with a microscope, it was observed that bubbles were generated in the refractive index adjusting agent with the rise in temperature and the bubbles expanded, and this was transmitted. It has been found to be associated with increased losses.

The above connector is designed so that the gap between the substrate, the capillary, the protective plate and the optical fiber is as small as possible, and the gap is almost completely filled with the adhesive, so that the inside of the connector becomes highly airtight. ing. On the other hand, the refractive index adjusting agent is reliably supplied to the butt portion of the optical fiber,
In addition, an amount sufficient to fill the opening of the capillary tube is supplied so as not to cause shortage due to transpiration or the like even during long-term use, and the capillary is confined inside the connector.

When the connection portion in such a state is heated, air existing in the gap between the capillary and the optical fiber or the gap between the capillary and the capillary expands and enters the refractive index adjusting agent,
The pressure due to the expansion of the bubbles covers most of the volume of the refractive index adjusting agent, causing the refractive index adjusting agent to move at the optical fiber butting portion, or causing the expanded bubbles to enter the optical fiber butting portion, thereby increasing transmission loss. It is thought to bring about.

The present invention has been made in view of the above problems, and has a structure in which a capillary mounting groove is provided at a central portion in a longitudinal direction of an upper surface, an optical fiber guide groove is provided at both ends, and a coating portion is provided at both ends. A substrate having a mounting groove, a capillary tube fixed to the capillary mounting groove of the substrate and having an opening at a central portion in the longitudinal direction, and a protective plate covering the upper surface of the substrate. The inserted optical fiber is inserted from both ends, the end faces of the optical fiber are abutted at the opening, and the abutting part is coated with a viscous refractive index adjusting agent. An optical fiber connector in which an optical fiber is mounted in a fiber guide groove and an optical fiber coating portion is mounted in a coating portion mounting groove, and the optical fiber connector is fixed to the substrate with an adhesive. And the external opening or end of at least one of the above capillary fine protective plate, characterized in that the formation of the vent path communicating.

If such a ventilation path is formed, even if the connection portion is heated to a high temperature and air existing in the gap between the optical fiber and the capillary expands, the air can escape to the outside through the ventilation path. , The pressure inside the connector does not rise,
Bubbles do not grow in the refractive index modifier.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings of the embodiment shown in FIGS.
The same components as those in FIGS. 12 to 15 described above are denoted by the same reference numerals. The refractive index adjusting agent is not shown.

FIGS. 1 to 4 show an embodiment of the present invention. This optical fiber connector is provided on a top surface of a substrate 11 at a position corresponding to an opening 17 of a capillary tube 12 so as to provide a lateral air passage. The groove 31 is formed.

FIGS. 5 and 6 show another embodiment of the present invention. This optical fiber connector is provided at a position corresponding to both ends of a capillary tube 12 on the upper surface of a substrate 11 so as to provide a lateral air passage. groove
32a and 32b are formed.

FIG. 7 and FIG. 8 show still another embodiment of the present invention. This optical fiber connector is provided on the upper surface of the substrate 11 at a position corresponding to the opening 17 of the capillary tube 12, and is provided with a lateral air passage. Holes 33 are formed.

FIGS. 9 and 10 show still another embodiment of the present invention. This optical fiber connector is provided with a ventilation hole 34 at a position corresponding to the opening 17 of the capillary tube 12 of the protective plate 13. Is formed.

FIG. 11 shows still another embodiment of the present invention. In this optical fiber connector, a protective plate 13 is divided into two parts at a central portion, and a position corresponding to an opening 17 of a capillary tube 12 is provided for an air passage. A gap 35 is provided.

In the above embodiments, the case where only one type of ventilation path is used has been described. However, two or more types of these ventilation paths may be combined.

[Effects of the Invention] As described above, according to the present invention, since the ventilation path communicating the opening or end of the capillary tube and the outside is formed in the substrate or the protection plate, the connection portion is heated to a high temperature. Even if air existing in the gap between the optical fiber and the capillary expands, the air can escape to the outside through the ventilation path,
Bubbles do not grow in the refractive index adjusting agent, so that an increase in transmission loss at high temperatures can be prevented. According to an experiment, it was confirmed that the connection loss using the connector of the present invention was increased by 0.1 dB or less even when heated to a high temperature, and there was substantially no increase in loss.

[Brief description of the drawings]

1 is a longitudinal sectional view of an optical fiber connector according to an embodiment of the present invention, FIG. 2 is a transverse sectional view taken along line AA of FIG. 1, FIG. 3 is a side view of the connector, and FIG. FIG. 5 is a plan view of the connector with the protective plate removed, FIG. 5 is a side view showing another embodiment of the present invention, FIG. 6 is a plan view of the connector with the protective plate removed, FIG. Is a longitudinal sectional view showing still another embodiment of the present invention, FIG. 8 is a transverse sectional view taken along line BB of FIG. 7, and FIGS. 9 and 10 show still another embodiment of the present invention. FIG. 11 is a longitudinal sectional view and a plan view, FIG. 11 is a plan view showing still another embodiment of the present invention, FIG. 12 is a longitudinal sectional view of an optical fiber connector on which the present invention is based, and FIGS.
Is a cross-sectional view taken along lines CC, DD, and EE in FIG. 12, and FIG. 16 is a graph showing an increase in transmission loss at a high temperature of a connection portion using a conventional connector. . 11: Substrate, 12: Capillary, 13: Protection plate, 14: Capillary mounting groove, 15
a ・ 15b: optical fiber guide groove, 16a ・ 16b: sheath mounting groove, 1
7: Opening, 21a / 21b: Optical fiber, 22: Refractive index adjuster, 23
a · 23b: coating, 24: adhesive, 31 / 32a, 32b: groove for air passage, 33/34: hole for air passage, 35: gap for air passage.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kenju Hirano 6 Yawata Kaigan-dori, Ichihara-shi, Chiba Furukawa Electric Co., Ltd. Chiba Works (72) Inventor Shigeru Tategami 6 Yawata-kaigan-dori, Ichihara-shi, Chiba Furukawa Electric (56) References JP-A-61-25109 (JP, A) JP-A-1-310312 (JP, A) Full-scale sho 59-51312 (JP, U) Full-scale sho-58- 16609 (JP, U)

Claims (1)

(57) [Claims] A capillary mounting groove is provided at a longitudinally central portion of an upper surface,
A substrate having optical fiber guide grooves at both ends thereof and a coating portion mounting groove formed at both ends thereof; a capillary tube having an opening at a longitudinal center portion fixed to the capillary mounting groove of the substrate; An optical fiber whose coating has been removed is inserted from both ends into the capillaries, the end faces of which are butted at the openings, and the butting portions have a viscous refractive index adjustment. An agent is applied, and an optical fiber is mounted in the optical fiber guide groove of the substrate, and a coating portion of the optical fiber is mounted in the coating portion mounting groove, and each is fixed to the substrate with an adhesive. An optical fiber connector, wherein at least one of the substrate and the protective plate is provided with an air passage for communicating an opening or end of the capillary tube with the outside. Optical fiber connector.