JPH0621890B2 - Manufacturing method of multilayer thin film star coupler - Google Patents

Description

The present invention relates to a method for manufacturing a multilayer thin film star coupler for optical communication.

Various researches and proposals have been made on star couplers (for example, Shogaku Shinshin University 337-341), but conventional ones are often single-layer or block-shaped, and the splice loss in fiber splices is compared. It was a big one.

(Object) An object of the present invention is to provide a star coupler capable of reducing the coupling loss at the connecting portion with the optical fiber, improving the mixing efficiency in the mixer portion, and arranging the input / output ports at a high density.

(Structure) In the method for producing the star coupler of the present invention, an optical waveguide is formed in a part of the substrate as in the conventional method (for example, JP-A-55-14).
9908), instead of the high refractive index rectangular waveguide thin films forming the optical waveguide (core part), the superposed body is formed by sandwiching the low refractive index thin film pieces forming the clad part at both ends. After each layer is adhered to each other under vacuum or normal pressure to form a laminated body, the whole is molded with a low refractive index synthetic resin to form a block body, and the optical waveguide thin film in the block body has a square cross section. It is characterized in that it is cut into a plate shape.

Further, a large number of flat plate star couplers thus obtained are stacked, and a two-dimensional optical waveguide cross-section is formed by the same method as above with a low-refractive-index thin film piece similar to the clad portion interposed between both ends thereof. A three-dimensional star coupler is obtained as a closely aligned laminated body.

The present invention will be described below with reference to the drawings.

In FIG. 1, 1 is a rectangular waveguide thin film having a high refractive index for forming a core portion, and 2 and 3 are clad thin film pieces having a low refractive index for forming a clad portion, which are both end portions 20 of the waveguide thin film 1. And 30, and the superposed body 4 is formed.

When the superposed body 4 is pressed by a suitable physical means under vacuum or in the atmosphere, the thin films in the central portion 40 are in close contact with each other as shown in FIG. A contact laminate having the area 8a is obtained. In this state, the whole is molded with a synthetic resin 5 having a low refractive index equal to or less than that of the crack portion to form one block 6 as a whole. When the block 6 of FIG. 2 thus formed is sliced at a right angle to the laminated surface, a flat plate body 7 having an end face as shown in FIG. 4 is obtained.

In the above, the thickness of each thin film should be determined depending on the optical fiber to be connected. For example, if the core diameter (d) of the fiber 10 is 50 μm and the clad diameter (D) is 100 μm, it is preferable that each thickness is 50 μm. is there.

Further, in the case of obtaining the flat plate body 7 from the block 6, if the plate 6 cannot be sliced directly to a desired thickness, the block 6 is fixed on an appropriate substrate and then sliced as thinly as possible to obtain a thickness equal to a desired thickness. And grind.
Note that the substrate may be cut off at unnecessary ends, or may be left as it is in some cases.

A two-dimensional star coupler is obtained by polishing both end faces of the flat plate thus obtained to form a core end face a and a clad end face b and connecting optical fibers.

In the star coupler of the present invention, the mixer section 8 is composed of a close contact body of high refractive index thin film, and each boundary 9 becomes a reflection layer. This reflection layer increases the intensity of scattering and increases the mixing efficiency of the mixer section 8, which also has the effect of improving the even distribution to the output ports.

In the above star coupler, since the mixer section 8 is a plate-shaped body, unevenness may be formed only in the mixer section in order to further improve the uniform distribution performance of this section.

That is, in the process of forming a contact laminated body or after that, corrugated, chamfered or hemispherical protrusions (diameter of about 1 m are formed on the surface.
m) the central part 4 which becomes the mixer part by the die
By pressing 0, the wavy shape can be formed in the mixer section.

It is considered that optical fibers are connected in multiple stages along the core layers on the end faces 6a and 6b of the block body in FIG. 2 to be used as a three-dimensional star coupler. However, in the usage pattern of 2, the loss at the core connecting portion increases. To do. The one shown in FIG. 5 is a solution to this.

That is, the sliced flat plate body 7 of FIG. 3 is regarded as one waveguide thin film, and the low refractive index thin film pieces 23 are provided on both ends 20 and 30, respectively.
1 and superimpose them in the same manner as in FIG. 1, and press the superposed body at its central portion and fill the space and the whole with synthetic resin.

As a result, a three-dimensional optical coupling portion is formed in the central portion, and the high-refractive-index optical waveguides a are exposed at the input / output port end faces in plan view at equal intervals, so that the optical fibers can be directly connected as a matrix.

The half-cut body obtained by cutting the flat plate body of FIG. 3 with AA can be used as a distributor by itself.

(Effect) As described above, according to the present invention, by laminating two kinds of thin films having different refractive indexes, the input / output ports are arranged at high density at both ends, and the two-dimensional or three-dimensional mixer section is provided in the middle section. It becomes possible to manufacture a plate-shaped two-dimensional star coupler and a block-shaped three-dimensional star coupler.

Also, the mixing efficiency in the mixer section can be improved by a simple means.

[Brief description of drawings]

FIG. 1 is a perspective view showing a production process of the coupler of the present invention, wherein (a) is a laminated body and (b) is a pressure laminated body.
2 is a perspective view of a molded state, FIG. 3 is a plan view of a sliced two-dimensional star coupler, FIG. 4 is an enlarged end view thereof, and FIG. 5 is an end view of a three-dimensional star coupler. 1 is a high refractive index waveguide thin film for core part construction, 2 and 3 are clad thin films, 4 is a superposed body, 8 is a mixer part, and 9 is a reflective layer.

Claims (2)

[Claims] 1. A step of forming a superposed body by sandwiching a clad thin film piece between both ends of a large number of rectangular waveguide thin films constituting an optical waveguide, and the thin films of the superposed body under vacuum or at ordinary times. A step of bringing them into contact with each other under pressure to form an adhesive laminate; a step of molding the adhesive laminate with a synthetic resin having a refractive index equal to or lower than that of the clad thin film to form a block body; A method of manufacturing a multi-layer thin film two-dimensional star coupler, which comprises a step of cutting a waveguide thin film into a plate shape so as to have a square cross section. 2. A step of forming a laminated body by sandwiching a clad thin film piece between both ends of a large number of rectangular waveguide thin films constituting an optical waveguide, and a step of forming each thin film of the laminated body under vacuum or at ordinary times. A step of bringing them into contact with each other under pressure to form an adhesive laminate; a step of molding the adhesive laminate with a synthetic resin having a refractive index equal to or lower than that of the clad thin film to form a block body; A step of cutting the waveguide thin film into a plate shape so as to have a square cross section, and inserting the clad thin film or a low refractive index thin film of the same degree as the clad thin film between both ends of the cutting flat plate body. A step of obtaining a superposed body,
Then, a method for producing a multilayer thin film three-dimensional star coupler, which comprises a step of forming a contact laminate and then molding the whole with a low refractive index synthetic resin.