JPS6035643B2 - How to assemble an optical branching/synthesizing circuit structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a branching/synthesizing circuit groove body for optical fibers.

In optical communication systems, the configuration of the signal distribution system is important.
A circuit for branching and combining optical signals is required.

Conventionally, directional couplers using thin film waveguides have been known as such branching/combining circuits, but this is unsuitable for multimode fibers because the size difference is too large. A particular problem with branch circuits suitable for multimode fibers is that the amount of branch coupling tends to change depending on the state of the excitation mode in the fiber.

The branching/combining circuit shown in Fig. 1A provides a relatively good solution to the problems peculiar to multimode fibers.
The oral method is known. In the figure, 1 is a fiber, 2 is a light source, 3 is a lens, and 4 is a beam splitter. Of both types, the mouth type has the advantage of being ultra-miniaturized and stable as there are no mechanical parts. By the way, in the optical method, it is necessary to optically polish the fiber end face diagonally, but the standard outer diameter of optical fibers used for optical communication is 100 to 200 m◇, and it is difficult to polish such a thin wire. It's not easy and it's expensive. Furthermore, with this method, it is necessary to align the optical axis of the light-receiving fiber within the vertical plane of the obliquely polished end face, but such adjustment is difficult due to the extremely small dimensions of the target. Become something. SUMMARY OF THE INVENTION However, an object of the present invention is to provide a method for assembling an optical branching/synthesizing circuit body which solves the above-mentioned difficulties.

The present invention will be explained below with reference to FIG.

In FIG. 2, substrates 11 and 12 are originally one glass or resin substrate that is cut at a predetermined angle Q and separated into two pieces. Grooves 21 and 2 for seating the line fibers la and lb before cutting the main board.
2 is formed in advance. Substrate 1 thus obtained
1 and 12 are aligned and fixed so that points A and A'' and points A and A river match, and then the sloped surface having the angle Q is finished. In this case both substrates will be finished at the same time. If the above processing method is adopted, the substrate 11,
By fixing the fiber seating grooves 21 and 22 so that the A-A'' plane abuts against the mount surface as shown in the figure, the fiber seating grooves 21 and 22 will not be misaligned.Next, the fiber for branched light transmission lc
A groove 31 for seating is formed in one of the substrates 11 so that the koji line is perpendicular to the axis of the groove 21. This groove 31 will be conveyed to the groove 21 at the face value. The fibers la are placed in the grooves 21, 22, and 31 of the obtained grooved substrate.
, lb, and lc are respectively seated and fixed with adhesive or the like.
Then, the transparent thin plate 40 is interposed on the inclined surface, and the curved surfaces of both substrates 11 and 12 are aligned so that the line fiber axes are aligned. Transparent plastic may be filled instead of the thin plate. This provides a horizontal body that provides branching or combining circuits. One surface of the transparent thin plate 40 is coated with a reflective film by vapor deposition of aluminum or the like. The groove 31 can also be used as a seating groove for a fiber for transmitting composite light. If necessary, this fuselage may be covered with another cover plate. According to the horizontal body of the present invention, the fiber end only needs to be a flat surface, and the conventional sloped surface is avoided.

Furthermore, by filling the groove gap A where the fiber ends gather with a transparent plastic material having an appropriate refractive index, the polishing accuracy of the fiber end face can be lowered. Furthermore, by using such a filler, the distance between the line fiber end faces can be increased without increasing optical loss between them.
It is allowed to be longer. According to the present invention, as shown in the figure, the seating groove 31 of the fiber for combined light transmission and the seating groove 32 of the fiber for branched light reception are simultaneously processed and provided with the substrates 11 and 12 aligned at face value, The aircraft can also be used as a circuit aircraft for branching and synthesis.

In this case, since a transparent thin plate is used as described above, the cores of the composite light transmitting fiber ld and the branched light receiving fiber lc may be completely misaligned. Therefore, it is possible to avoid inputting the combined light into the branched light receiving fiber lc. Further, according to the present invention, there is an advantage that the amount of synthetic bonds and the amount of branched bonds can be controlled by appropriately controlling the difference in refractive index between the filler and the transparent plate.

[Brief explanation of the drawing]

1A and 1B are explanatory diagrams showing a conventional branching/combining circuit system, and FIG. 2 is an explanatory diagram showing a horizontal branching/combining circuit according to the present invention. In the figure, la, lb, lc, ld are fibers, 1
1 and 12 are substrates, 21, 22, 31, and 32 are fiber seating grooves, and 40 is a transparent thin plate. Figure 1 Figure 2

Claims (1)

[Claims] 1. After forming a straight line fiber on one substrate by penetrating the seating groove, cut the substrate so that the cut surface is a plane that intersects the straight line, and at least one of the substrates. Form seating grooves for the fibers for branch roads and/or composite roads at a predetermined angle with respect to the seating grooves for the railway fibers, seat and fix the fibers corresponding to each seating groove, and then attach the fibers to both substrates. A method for assembling an optical branching/synthesizing circuit structure, characterized in that a transparent material is interposed between the cut surfaces of the two substrates, and the axes of the line fibers fixed to both substrates are aligned so as to coincide with each other.