JPS5885413A - Forming method for optical fiber multiterminal - Google Patents

Abstract

PURPOSE:To eliminate the technically skilled work, by working an optical fiber and a hollow tube obliquely at a prescribed angle and working end faces of the optical fiber and the hollow tube obliquely at a prescribed angle and connecting plural optical fibers and hollow tubes, which are worked in this manner, by adhesion. CONSTITUTION:An optial fiber 10 is inserted into a ceramic hollow tube 11, and they are ground obliquely at a prescribed angle thetaa while leaving a core part 14 of the optical fiber 10 as it is. In this state, end faces of the optical fiber 10 and the hollow tube 12 are polished obliquely at a prescribed angle thetab to a plane vertical to a slope 12a. Slopes 12a of two optical fiber hollow tubes 12 which are polished obliquely symmetrically in this manner are connected by an adhesive. The light transmitted along an optical axis D-D of the hollow tube 12 is refracted on an end face 12b and is emitted in parallel with a center line A-A of connection.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming optical coupling of multiple terminals of an optical fiber for optical communication.

When you want to combine multiple light waves and strengthen the light intensity, or use WDM (wave length
When using a multipex (division multipex) method, it requires one person's effort, multiple outputs or multiple inputs, and spatial demultiplexing and synthesis of light with one output. A combiner is used when the wavelengths are the same, and a multiplexer is used when the wavelengths are different. In particular, WDM is said to be economically advantageous when combined with an FDM system using a normal carrier wave, and this connection configuration is required.

Generally, a demultiplexer or multiplexer using an optical interference filter or a diffraction grating is used for this purpose, but direct coupling is required to reduce loss due to spatial propagation.

FIG. 1 is an explanatory diagram of a conventional single mode optical fiber processing method. Part of the core of optical fiber 1 (approximately 50μm
) The cladding portion 3 close to 2 is dissolved and removed using hydrogen fluoride (HF). The outer IMd of the shaft 2 after this melting is slightly thicker than the diameter of the core part 4.

FIG. 2 is a side view showing a state in which the optical fibers of FIG. 1 are joined by a melted shaft portion 2. FIG. Each optical fiber single axis section 2
Accurately fuse the contacting parts of each other while keeping their axes parallel to each other,
Or glue. This method requires a high degree of skill. In particular, if the shaft parts 2 are not close enough, a speed difference will occur when the light waves emitted from the two core parts 4 enter the core part (not shown) of one opposing optical fiber, and mode conversion will occur. It happens easily. Furthermore, since the exposed shaft portion 2 has less cladding portion 3 of the reflective layer, there is a drawback that loss increases.

FIG. 3 is a perspective view of another conventional single mode optical fiber processing method.

(A) Figure shows before connection, (B) Figure shows after connection.

(a) In the figure, two optical fibers 5 are placed with their axes facing each other, arc-discharge melted (spliced), and their tips mutually bonded. If they are pulled apart while still hot, they will extend into a candy-like shape and become long and loose. (b) As shown in the figure, the 5° taper portions 6 of these two optical fibers are fused and bonded to each other.

This method also requires handicraft skills, and it is not easy to accurately determine the precision and straightness of the tapered portion, especially the position and diameter of the core portion, and it is difficult to manufacture uniformly in large quantities.

The present invention eliminates the above-mentioned skilled and technical work. That is, in an optical fiber coupling section for optical multiplex communication, an optical fiber is inserted into a hollow tube and bonded, leaving a part of the core of the optical fiber. , an optical fiber and a hollow tube are both processed diagonally at a predetermined angle in the axial direction, and the end surfaces of the optical fiber and the hollow tube are both processed diagonally at a predetermined angle with respect to the axial direction. The objective is to establish a mass production method with good reproducibility using an optical fiber multi-terminal molding method characterized by adhesive bonding.

Examples according to the present invention will be described in detail below.

Note that the same reference numerals in the figures from FIG. 4 to FIG. 9 indicate the same parts.

FIG. 4 is a cross-sectional view of a single mode optical fiber processing method according to the present invention.

B) The figure is a perspective view of the optical fiber before being joined.

Figure (b) is a cross-sectional view of the optical fiber after bonding.

b) In the figure, the optical fiber 10 is inserted into the ceramic hollow tube 11, and the optical fiber 10 is ground diagonally to a predetermined angle θa ((b) shown in the figure), leaving a part of the core 14 of the optical fiber 10. The outer diameter of the optical fiber is generally approximately 125 mm.
μm, but it is currently possible to sinter and form ceramic into a hollow tube using a wire with the same outer diameter as the mandrel, and sufficient accuracy can be obtained.
This hollow tube 11 is utilized in the present invention.

It is also relatively easy to insert the optical fiber IO through the hollow tube 11. In the present invention, the optical fiber 10 is inserted into the hollow tube IJ and held with a jig in a state where it is bonded, and polished at a predetermined angle θa parallel to the optical axis of the optical fiber 10. Next, keep the same state as the optical fiber 10 and the hollow tube 1.
The end face of 2 is polished obliquely to a predetermined angle θb (as shown) with respect to the perpendicular surface of the slope 12a. For the sake of explanation, this state will be tentatively named optical fiber hollow tube 12.

(B) In the figure, the surfaces 12a of two hollow optical fiber tubes 12 are symmetrically polished obliquely and joined together with an adhesive. For the sake of explanation, this state will be temporarily named a spliced optical fiber hollow tube 13.

The optical axis of each hollow optical fiber tube 12 is inclined by an angle θa with respect to the joining center line A-8 of each hollow optical fiber tube 12, and the end surface 12b of the hollow optical fiber tube 12 is It is inclined at an angle θb with respect to a surface perpendicular to the slope 12a of the empty tube 12.

The reason for this is that the output optical axis C- of the two optical fiber hollow tubes 12
This is to make C parallel and coincide with the basic optical axis of the opposing optical fiber. That is, the optical axis D- of the optical fiber hollow tube 12
The light propagating along D is refracted at the end face 12b and exits parallel to the bonding center line AA. Therefore θa
The relationship between and θb is θb−θa/(n−1), where n is the refractive index of the optical fiber. In this example, θa is 5'
selected.

FIG. 5 shows an end face of the spliced optical fiber hollow tube 13 viewed from the direction of arrow B in FIG. Core part 14 of optical fiber 10
are close to each other.

FIG. 6 is a sectional view of the end face of a spliced optical fiber when a plurality of input lights are input. The figure (a) shows the case of three input lights, and the figure (b) shows the case of four input lights. In either example, the output light from a part of the core is multiplexed and input into the opposing optical fiber.

FIG. 7 shows a configuration diagram of another embodiment of two-man power, (1) output coupling using an optical fiber hollow tube. Optical fiber hollow tube 12
The output optical axis of is processed and formed at an angle θb in a direction that is slightly open from the welding center line A-A.

The two light waves enter the lens 13, become parallel light beams, and after spatial propagation are condensed again by the lens 15 and enter the optical fiber 16.

FIG. 8 is a block diagram of an embodiment of a duplexer using a hollow optical fiber tube. The optical fiber hollow tube 21 is used for single-mode input light, and the optical fiber hollow tube 21'' is used for multi-mode output light. In this embodiment, the coupled optical fiber hollow tube 23
The end surface 23a constitutes a surface perpendicular to the joint center line A-A.

The optical interference filter 22 is also provided perpendicularly to the joining center line AA line. A condensing lens 23 is provided on the optical axis extension fiber of the optical fiber hollow tube 21 on the left side of the optical interference filter 23 in the figure, and an optical fiber 24 is further provided close to the condensing lens 23. It is arranged on the optical axis extension of the optical fiber hollow tube 21.

Two light waves with wavelengths λ1 and λ2 from the optical fiber hollow tube 21 are split by an optical interference filter 22 into reflected light (temporarily assumed to be λ1) and transmitted light (temporarily assumed to be λ2). reflected light λ
1 becomes multi-mode and is propagated through the optical fiber hollow tube 21'. On the other hand, the transmitted light λ2 is condensed by the condenser lens 23, inputted from the end face of the optical fiber 24, and propagated.

FIG. 9 is a block diagram of another embodiment of a duplexer using a hollow optical fiber tube. Fiber optic hollow tubes 31, 31' and 3
4 is the same as in FIG. 7, but the angle θb is equal to the angle θa. However, both optical fibers are in close contact with the interference filter 32 and there is no spatial propagation.

In this example, ceramic is used for the hollow tube, but it is assumed that metal, glass, etc. can also be used with the development of hole processing technology.

As described above, according to the present invention, the structure that multiplexes input light from a plurality of optical fibers into a single optical fiber and propagates the structure does not require skilled skills and can be reliably manufactured mechanically. Mass production is easy.

Furthermore, it is stable in terms of quality and highly reliable.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the conventional single-mode optical fiber processing method, Figure 2 is a side view showing the state in which two optical fibers in Figure 1 are joined at a part of the core, and Figure 3 is an explanatory diagram of the conventional single-mode optical fiber processing method. A perspective view of another single mode optical fiber processing method, (a) shows the state before connection, and (b) shows the state after connection. FIG. 4 is a cross-sectional view of the single-mode optical fiber processing method according to the present invention, (a) is a perspective view of the optical fiber before bonding, and (b) is a cross-sectional view of the optical fiber after bonding. FIG. 5 shows an end face of the spliced optical fiber hollow tube 13 viewed from the direction of arrow B in FIG.
FIG. 6 is a cross-sectional view of the end face of an optical fiber when a plurality of input lights are used, FIG. 6A shows a case where three human-powered lights are used, and FIG. FIG. 7 is a block diagram of another embodiment of a two-manpower, one-output coupling using a hollow optical fiber tube, and FIG. 8 is a block diagram of an embodiment of a duplexer using a hollow optical fiber tube. FIG. 9 is a block diagram of another embodiment of a duplexer using a hollow optical fiber tube. ? In the figure, 10 is an optical fiber and 11 is a hollow tube. /θ 1st Figure 2/2b 15 / Figure 6'f38c,. Figure 9・□

Claims (1)

[Claims] In the optical fiber coupling part of optical multiplex communication, an optical fiber is inserted into a hollow tube and glued, and both the optical fiber and the hollow tube are processed diagonally at a predetermined angle in the axial direction, leaving a part of the core of the optical fiber. . A method for forming multiple terminals of optical fibers, further comprising adhesively bonding a plurality of optical fibers and hollow tubes whose end surfaces are both processed obliquely at a predetermined angle with respect to the axial direction.