JPH0228603A - Optical fiber connector - Google Patents

Abstract

PURPOSE:To prevent the intrusion of an expanded air bubble into the butt part of optical fibers and the consequent increase of a transmission loss by forming a vent path communicating the aperture or the end of a capillary and the outside to a base plate or protective plate. CONSTITUTION:The vent path 31 communicating the aperture 17 or the end of the capillary 11 and the outside of formed to the base plate 11 or the protective plate 13 and, therefore, the air existing in the spacing between the optical fibers 21a, 21b and the capillary 12 or the like escapes to the outside by passing the vent path 31 even if said air expands as the juncture is heated to a high temp. The growth of the air bubble in a refractive index adjusting agent is obviated in this way and the increase of the transmission loss at the time of the high temp. is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a connector for connecting optical fibers.

[Prior art]

The present inventors previously developed optical fiber connectors as shown in FIGS. 12 to 15. This connector is composed of a substrate 11, a capillary tube 12, and a protection plate 13.

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

Further, the capillary tube 12 is made of glass or ceramic, and the capillary tube 12 is made of glass or ceramic.
It is fixed to the capillary tube mounting groove 14 of No. 1 with an adhesive or the like, and an opening 17 is formed in the center in the longitudinal direction. The protection plate 13 is made of plastic, and is placed and fixed on the top surface of the substrate 11 after the optical fiber 5 is connected.

Note that guides 18 for positioning the protection plate 13 are provided protruding from the four corners of the substrate 11.

Connection of optical fibers using this connector is performed as follows.

The capillary tube 12 has optical fibers 21a and 2 whose coatings have been removed.
The capillary tube 12 placed in the capillary tube attachment groove 14 and the optical fiber guide groove 15a and 15b, into which the capillary tube 1b is inserted from both ends and whose end surfaces are butted against each other at the opening 17, Since the axes of the optical fibers 21a and 21b placed on the capillary tubes 15a and 15b coincide with each other, the optical fibers 21a and 21b placed on the capillary tube 12
- To insert the optical fibers 21b, slide the optical fibers 21a and 21b along the optical fiber guide grooves 15a and 15b (
This can be done easily. Also, optical fiber 2
A refractive index adjusting agent 22 having viscosity is applied to the abutting portions 1a and 21b.

Furthermore, the covering parts 23a and 23b of the optical fibers 21a and 21b are attached to the covering part mounting grooves 16a and 16b of the substrate 11, and are fixed to the substrate with an adhesive 24. In this state, the protection plate 13 is placed on the top surface of the substrate 11 and fixed to the substrate 11 with adhesive, clips, screws, or the like. The connection is now complete.

〔assignment〕

This newly developed connector has the advantage of being able to easily and accurately connect optical fibers, but
After connection, various tests were conducted and it was found that when exposed to high temperatures, transmission loss may increase to the extent that it becomes a practical problem. Figure 16 shows an example of transmission loss measurement results.

In order to investigate the cause of this, we heated the optical fiber connection to a high temperature and observed it under a microscope. As the temperature rose, we observed that bubbles were generated in the refractive index adjusting agent and expanded. It was found that this was associated with an increase in losses.

The above connector is designed to minimize the gaps between the substrate, capillary tube, protection plate, and optical fibers, and since the gaps are almost filled with adhesive, the inside of the connector is highly airtight. ing. On the other hand, the refractive index adjusting agent is supplied in an amount sufficient to fill the opening of the capillary tube, so that it is reliably supplied to the butt part of the optical fiber and does not run out due to transpiration, etc. even during long-term use. and is trapped inside the connector.

When the connection in this state is heated, the air existing in the gap between the capillary tube and the optical fiber or the gap between the capillary tubes expands and enters the refractive index adjusting agent, causing the bubbles to expand. The pressure caused by this will affect most of the volume of the refractive index adjusting agent, and may cause the refractive index adjusting agent in the optical fiber butt portion to move or expand air bubbles to enter the optical fiber butt portion, resulting in an increase in transmission loss. Conceivable.

[Means for solving problems and their effects]

The present invention was developed to solve the above-mentioned problems, and has a structure that includes a capillary tube mounting groove in the longitudinal center of the upper surface, optical fiber guide grooves on both ends thereof, and optical fiber guide grooves on both ends thereof. It consists of a substrate in which a covering part mounting groove is formed, a capillary tube fixed to the capillary fitting groove of this board and having an opening in the longitudinal center, and a protective plate placed on the upper surface of the substrate, and the capillary tube is provided with a covering part. The optical fiber from which the fiber has been removed is inserted from both ends, and their end faces are abutted in the opening, and a viscous refractive index adjusting agent is applied to the abutted portion, and the substrate is In the optical fiber connector, the coating section of the optical fiber is attached to the coating section mounting groove of the optical fiber connector, and the coating section of the optical fiber is fixed to the substrate with an adhesive. It is characterized by forming a ventilation path that communicates the end portion with the outside.

If such a ventilation path is formed, even if the connection part is heated to a high temperature and the air existing in the gap between the optical fiber and the capillary tube expands, that air will be able to escape to the outside through the ventilation path. , the pressure inside the connector will not increase and bubbles will not grow in the refractive index modifier.

〔Example〕

Hereinafter, embodiments of the present invention will be explained in detail with reference to the drawings. In the drawings of the embodiments shown in FIGS.
Components that are the same as those in FIGS. 12 to 15 described above are given the same reference numerals. Further, the illustration of the refractive index adjusting agent was omitted.

Figures 1 to 4 show an embodiment of the present invention.
This optical fiber connector has a groove 31 for a ventilation passage formed in the horizontal direction on the upper surface of a substrate 11 at a position corresponding to the opening 17 of the capillary tube 12.

5 and 6 show another embodiment of the present invention, in which this optical fiber connector is provided with a vent passage in the upper surface of the substrate 11 at a position corresponding to both ends of the capillary tube 12 in the lateral direction. Grooves 32a and 32b are formed therein.

7 and 8 show still another embodiment of the present invention, in which this optical fiber connector has a hole 3 for an air passage in a position corresponding to an opening 17 of a capillary tube 12 in a substrate 11.
3 was formed.

FIG. 9 and FIG. 10 show still another embodiment of the present invention, and this optical fiber connector has a protective plate 13,
A hole 34 for a ventilation path is formed at a position corresponding to the opening 17 of the capillary tube 12.

FIG. 11 shows still another embodiment of the present invention, in which the protective plate 13 is divided into two parts at the center, and a ventilation path is provided at a position corresponding to the opening 17 of the capillary tube 12. A gap 35 is provided.

In the above embodiments, the case where each type of air passage is used is explained, but two or more types of these air passages may be combined.

〔Effect of the invention〕

As explained above, according to the present invention, the air passage that communicates the opening or end of the capillary with the outside is formed in the substrate or the protective plate, so that the connection part is heated to a high temperature, and the optical fiber and the capillary are connected to each other. Even if the air that exists in the gaps expands, the air can escape to the outside through the ventilation passages, so bubbles will not grow in the refractive index modifier, thus reducing the increase in transmission loss at high temperatures. It can be prevented.

According to experiments, it was confirmed that even when a connection part using the connector of the present invention is heated to a high temperature, the transmission loss increases by 0.1 dB or less, and there is virtually no increase in loss.

[Brief explanation of the drawing]

Figure 1 is a longitudinal sectional view of an optical fiber connector according to an embodiment of the present invention, Figure 2 is a cross sectional view taken along line A-A in Figure 1, Figure 3 is a side view of the connector, and Figure 4. 5 is a side view showing another embodiment of the present invention, FIG. 6 is a plan view of the same connector with the protective plate removed, and FIG. 7 is a plan view of the same connector with the protective plate removed. 8 is a longitudinal cross-sectional view showing still another embodiment of the present invention, FIG. 8 is a cross-sectional view taken along the line B-B in FIG. 7, and FIGS. A vertical sectional view and a plan view, FIG. 11 is a plan view showing still another embodiment of the present invention, FIG. 12 is a vertical sectional view of a conventional optical fiber connector, and FIGS. 13 to 15 are respectively FIG. FIG. 16 is a graph showing an increase in transmission loss at a high temperature in a connection section using a conventional connector. 11: Substrate, 12: Capillary, 13: Protective plate, 14: Capillary mounting groove, 15a/15b: Optical fiber guide groove, 16a
・16b: Covering part mounting groove, 17: Opening, 21a・21
b: Optical fiber, 22: Refractive index adjusting agent, 23a/23b
: Covering part, 24: Adhesive, 3132a-32b: Groove for ventilation passage, 33 and 34: Hole for ventilation passage, 35: Gap for ventilation passage. Figure- Ikkei Encounter L Danbun (Time)

Claims (1)

[Claims] 1. A substrate with a capillary tube mounting groove formed in the center in the longitudinal direction of the upper surface, optical fiber guide grooves on both ends thereof, and coating section mounting grooves formed on both ends thereof, and a longitudinal side fixed to the capillary tube mounting groove of this substrate. It consists of a capillary tube having an opening at the center in the direction, and a protection plate placed over the top surface of the substrate, and an optical fiber with its coating removed is inserted into the capillary tube from both ends, and its end surface is inserted into the opening. A refractive index adjusting agent having viscosity is applied to the abutting portion of the optical fiber, and the coating portion of the optical fiber is attached to the coating portion mounting groove of the substrate, and the coating portion of the optical fiber is attached to the substrate using an adhesive. An optical fiber connector adapted to be fixed to an optical fiber connector, characterized in that at least one of the substrate and the protection plate is formed with a ventilation path that communicates the opening or end of the capillary tube with the outside. .