JPS62226107A - Optical fiber connection structure - Google Patents

Abstract

PURPOSE:To make a connection without causing the loss of optical coupling characteristics nor requiring any special equipment and to facilitate and speed up the connection operation by fitting and fixing a tube made of a material which is equal in refractive index to the clads of optical fiber to be connected mutually around end parts of the optical fibers and filling liquid material which is equal in refractive index to the cores of the optical fiber into the tube. CONSTITUTION:The tube made of the material which is equal in refractive index to the clads of the optical fibers to be connected mutually is fitted and fixed around the end parts of the two optical fibers, and the liquid material which is equal in refractive index to the cores of said optical fibers is charged into the tube. Light propagated in the core 2a reaches an extremely small gap 5 and is reflected totally by the boundary surface between the liquid material and tube 4 when entering the liquid material 6 to enter the core 2b of the other optical fiber 1b because the liquid material 6 is equal in refractive index to the cores 2a and the tube 4 present at its periphery is also equal in refractive index to the clads 3, so that optical transmission having no loss is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a connection structure for optically coupling optical fibers.

[Conventional technology]

When optical fibers used for optical communications are optically coupled in the length direction, there is a method of connecting both optical fibers using a connector, but since connectors are expensive, there is a method of directly connecting the optical fibers. is often taken. Conventionally, when optical fibers are directly connected in this way, a method called splicing has been adopted.

In this method, the ends of two optical fibers to be connected to each other are melted and then brought together and welded to connect them.

[Problem that the invention seeks to solve]

In the conventional connection method described above, in order to prevent loss of optical coupling characteristics at the connection surfaces of two optical fibers, it is necessary to polish each end surface flat, and it is necessary to align each end surface and furthermore, There is a problem in that experience and skill are required for the work, such as the need to perform the work of melting the parts and abutting the parts accurately and quickly.

In addition, this method requires special equipment to melt the end face of the optical fiber, and requires a power source to operate it, making it complicated to carry and handle. be.

[Means for solving problems]

The optical fiber connection structure of the present invention makes it possible to connect optical fibers without causing loss of optical/optical coupling characteristics and without requiring special equipment, and also simplifies and speeds up the connection work. This is what we aim to do.

The optical fiber connection structure of the present invention has two optical fibers connected to each other.
A tube made of a material with a refractive index equal to that of the cladding of the optical fiber is fitted and fixed to each end of the optical fiber, and this tube is filled with a liquid substance having a refractive index equal to the core of the optical fiber. .

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a sectional view of an embodiment of the present invention. The optical fibers la and lb connected to each other each have a core 2a made of a material with a high refractive index as is known in the art.

2b, and a core 2a provided around the cores 2a and 2b,
Claddings 3a, 3 made of a material with a refractive index lower than that of cladding 2b.
The optical fibers 1a and 1b are configured such that the light transmitted through the optical fibers 1a and 1b is transmitted through the cores 2a and 2b while being totally reflected at the interface between the cores 2a and 2b and the claddings 3a and 3b. ing.

These two mutually connected optical fibers 1a+1b have cylindrical tubes 4 fitted at opposite ends,
This tube 4 connects the cores 2a, 2b and cladding 3a of each optical fiber la, lb.

3b are maintained in a concentric positional relationship with each other, and are fixedly supported with their respective end surfaces facing each other with a minute interval t. The tube 4 is made of a material having the same refractive index as the claddings 3a and 3b of the optical fibers la and lb. The core 2a is located within the gap 5 with a minute interval t defined by the tube 4 and the ends of each of the optical fibers la and lb.

It is filled with a transparent liquid substance 6 having a refractive index equal to 2b.

When filling the cavity 5 with this liquid substance 6, for example, a tube 4 is inserted into the pore 7°8 that communicates the inside of the cavity 5 with the outside.
A method is adopted in which the liquid substance 6 is injected through one of the pores 7, air is removed from the other pore 8, and then these pores 7 and 8 are sealed with an adhesive 9 or the like. Bye.

According to this configuration, as shown in FIG. 2, the light transmitted through the core 2a of the optical fiber 1a reaches the gap 5 at minute intervals from its end face and enters the liquid substance 6. be done. Then, since this liquid substance 6 has the same refractive index as the core 2a, and the refractive index of the tube 4 existing around it has the same refractive index as that of the cladding 3a, the light passes through the interface between the liquid substance 6 and the tube 4. The light is totally reflected at , and enters the core 2b of the other optical fiber 1b, thereby realizing lossless optical transmission.

At this time, since the refractive index of the liquid substance 6 is equal to that of the cores 2a and 2b, even if the end surfaces of the cores 2a and 2b of each optical fiber la and lb are not polished flat, light will be abnormally refracted at this interface. Therefore, the transmission of light described above is not inhibited.

Therefore, according to this optical fiber connection structure, since the connected optical fibers la and lb are connected via the liquid substance 6 having the same refractive index as the core, both optical fibers la and lb
, 1. The connection loss (coupling loss) between b can be made extremely small, and the optical coupling characteristics can be improved.

In addition, the work required to connect both optical fibers la and lb is to fit the tube 4 to the opposing ends of each optical fiber la and lb and fix them, and to create a definition between each optical fiber. It is only necessary to fill the liquid substance 6 into the finely spaced voids 5 using the pores 7 and 8. In this case, each of the optical fibers la and lb can be substantially automatically positioned in a concentric relationship by fitting and fixing the tube 4.

Therefore, no experience or skill is required for the work, no special equipment is required, and the connection can be completed extremely easily and quickly.

〔Effect of the invention〕

As explained above, the present invention involves fitting and fixing a tube made of a material with a refractive index equal to the cladding of the optical fiber to the end of each optical fiber, and a liquid having a refractive index equal to the core of the optical fiber inside the tube. Since the structure is filled with a substance, it is possible to reduce optical coupling loss in each optical fiber and realize a suitable connection. Moreover, it eliminates the need for polishing the end face of each optical fiber, alignment of both optical fibers, and melting of both optical fibers, which eliminates the need for experience or skill and makes the connection work extremely easy. can.

[Brief explanation of drawings]

FIG. 1 is a sectional view of one embodiment of the present invention, and FIG. 2 is a schematic sectional view for explaining the state of optical transmission. la, lb...optical fiber, 2a, 2b...core,
3a, 3b...Clad, 4...Tube, 5...
・Void, 6...Liquid substance, 7,8...Pore, 9...
・Adhesive material.・＼? Figure 1 Figure 2

Claims (2)

[Claims] (1) In a connection structure that optically couples optical fibers consisting of a core and a cladding in the length direction, each end of two optical fibers to be connected to each other is made of a material with a refractive index equal to that of the cladding of the optical fiber. What is claimed is: 1. An optical fiber connection structure characterized in that a tube is fitted and fixed, and a liquid substance having a refractive index equal to the core of the optical fiber is filled in the tube. (2) The optical fiber connection structure according to claim 1, wherein a liquid substance is filled in a gap at minute intervals defined by the opposing end surfaces of the tube and each optical fiber.