JPS6028325B2 - Manufacturing method of optical fiber end - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing an optical fiber end for highly efficient coupling of a light source such as a semiconductor laser and an optical fiber.

When coupling an optical fiber to a semiconductor laser, it is difficult to achieve highly efficient coupling because the orientation angle of the optical fiber and the orientation angle of the semiconductor laser are too different.

For this reason, conventionally, the end of the optical fiber was processed into a lens shape as shown in FIG. 1A by heating or polishing. In the figure, 1 is the core and 2 is the cladding. When the dimensions of the core and cladding are not much different, the end of the core becomes sufficiently convex to the lens as shown in FIG. 1A.
As shown in FIG. 18, when the diameter of the core becomes smaller, no radial effect can be expected with the same configuration. Therefore, the coupling efficiency between the semiconductor laser and the optical fiber does not increase. Therefore, in order to increase the coupling efficiency, methods have been proposed in which a lens of the same size as the core is processed and bonded to the end of the optical fiber, but this method is extremely difficult to process and is not industrially viable.
Also, since adhesives are used, there is a risk of deterioration over time. The present invention has been proposed to eliminate these drawbacks.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is intended to provide an optical fiber end portion capable of highly efficient coupling and a method for manufacturing the same, and the present invention will be described in detail below with reference to the drawings.

FIG. 2 shows the end portion made by the method of the present invention, where 1 is the core, 2 is the cladding, and 3 is the core portion, where only the end portion of the core is formed into a convex surface.

Also, since the medium at the end of the core is a processed core,
It has the same soot quality as the core and is continuous. FIG. 3 shows a manufacturing method for forming the end of the core into a convex surface.

4 and 4' are discharge electrodes for heating, which are arranged on both sides of the end of the core.

5 is a power supply of approximately 4KV.

The melting point of the core is more than 100 qo lower than the melting point of the cladding, so when the cladding part 2' is heated, the core part 1' has reached its melting point at that point, so the cladding becomes slightly thinner due to the surface tension of the cladding part. Therefore, a portion of the core portion is pushed out to form a convex portion shown at 3. At this point, discharge heating is stopped. In order to make the melting point of the core lower than that of the cladding, the cladding may be made of fused silica, and the core may be made of fused silica doped with phosphorus, germanium, or the like. When a phosphorus-doped multimode optical fiber with a core diameter of 60 Am was used as an experimental example, the radius of curvature of the convex portion of the modulus was approximately 100 rm, and a sufficient lens effect was observed. Note that it is desirable that the difference in melting point between the core portion and the cladding portion be approximately 100 qo or more. Note that if the temperature is less than 100°C, the core portion will not be sufficiently melted, which is not preferred in practice. As described above, in the present invention, since the convex portion is made of the same material as the core, there is no change over time, highly efficient coupling can be expected, and the manufacturing method is extremely easy.

The present invention is also effective as a means for forming an end face of a single mode optical fiber having a small core diameter.

[Brief explanation of the drawing]

1A and 1B are conventional optical fiber ends, FIG. 2 is a sectional view of an optical fiber end made by the method of the present invention, and FIG.
The figure shows the manufacturing method. 1, 1'... core, 2, 2'... clad, 3...
Convex portion, 4, 4'...electrode, 5...power supply. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. Heat the vicinity of the smooth end face of an optical fiber, where the melting point of the core part is 100°C or more lower than the melting point of the cladding part, to such an extent that the cladding part melts, and the surface tension of the cladding part causes the tip of the cladding part to become thinner. A method for manufacturing an optical fiber end, comprising extruding the core from the smooth end surface to form a convex surface.