JPH06174955A - Production of optical wave guide - Google Patents

Abstract

PURPOSE:To provide the production method of the optical wave guide which is easy to control the refractive index of a core layer and simple in production stages. CONSTITUTION:A clad layer member 6 and a core layer member 7 is heated and melted to produce the wave guide base material 8 having nearly circular shape whose structure of the vertical cross section in a longitudinal direction are similar figures, and the wave guide base material 8 is heated and stretched up to a prescribed core layer width in a longitudinal direction, and the stretched wave guide base material 8 is cutted in a prescribed thickness is right angle direction in the longitudinal direction or the outer periphery part of the base material is polished after cutting, and the clad layer is stuck on the two surfaces where the core layer is exposed at the cut surface of the cut base material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical waveguide comprising a clad layer and a core layer for confining and guiding light in the core layer, and more particularly to a method for manufacturing the optical waveguide.

[0002]

2. Description of the Related Art FIG. 5 shows, for example, JP-A-58-10511.
This is the conventional method of manufacturing an optical waveguide shown in Japanese Patent Laid-Open No.

Conventionally, as a method for forming a core layer, for example, a torch including a material for forming a core layer (a glass film having a different refractive index) from a glass fine particle synthetic torch 2 as shown in FIG. While being exhausted by the exhaust pipe 3, the glass layer 4 is sprayed onto the glass substrate 1 to form a core layer.
Or CVD (Chemical Vapor Depo
film was formed by the method.

The core layer formed as described above ((b) in the figure) is used as a clad layer after forming a core circuit (waveguide portion) by reactive etching ((c) in the figure). An optical waveguide was manufactured by forming a corresponding protective film (embedding a glass layer by overcladding) (FIG. 3D).

[0005]

As described above, according to the conventional method for manufacturing an optical waveguide, the glass film corresponding to the core layer having a high refractive index formed on the glass substrate is sintered by the flame deposition method. When this is done, there is a problem that the refractive index cannot be controlled because the dopant content of the glass film corresponding to the core layer depends on the substrate temperature during film formation.

When the CVD method is used, the film thickness and
Although the reproducibility and uniformity of the refractive index are improved, the composition of the glass particles and the temporal fluctuations occur depending on the type of material of the glass film that corresponds to the core layer, so that it becomes non-uniform on a microscopic scale. There was a problem such as that.

Further, in the conventional manufacturing method, the etching process must be deeply performed to 5 to 20 μm in order to form the core layer, and there is a problem that productivity is poor.

The present invention has been made to solve the above problems, and an object thereof is to provide a method for manufacturing an optical waveguide in which the refractive index of the core layer can be easily controlled and the manufacturing process is simple. .

[0009]

According to the method of manufacturing an optical waveguide according to the present invention, a waveguide base material having a substantially circular shape in which a structure of a cross section perpendicular to the longitudinal direction has a similar shape is manufactured (waveguide matrix). Material manufacturing step), the waveguide base material is heated and stretched in the longitudinal direction until the core layer has a predetermined width (base material stretching step), and the stretched waveguide base material is oriented in a direction orthogonal to the longitudinal direction. Or cut the base material outer peripheral portion after the cutting (base material processing step) to form a clad layer on the two cut surfaces of the cut base material where the core layer is exposed. It is characterized by adhering (clad forming step).

This waveguide base material is manufactured by heating and fusing the clad layer member and the core layer member, and the clad layer member formed of SiO ₂ doped with an element that lowers the refractive index is used as the core layer. It is characterized in that the portion corresponding to is fixed in advance as a space, and is fixed by heating and manufactured by fusion.

[0011]

In the method of manufacturing an optical waveguide according to the present invention, since the waveguide base material is preliminarily formed from a member having a uniform refractive index and a plurality of core portions are formed from the same base material, the refractive index is uniform. Turn into.

Further, when a clad layer member formed of SiO ₂ doped with fluorine is fixed in a space corresponding to the core layer in advance and heat fusion is performed, the fluorine is volatilized on the surface of the clad layer member facing the clad layer member. In the vicinity of the center of the space that was used for this purpose, the fluorine content concentration was almost 0 (Wt
/%), And the core layer is formed in the fusion-bonded region that was the space.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In the drawings, the same parts are designated by the same reference numerals and the description thereof will be omitted.

FIG. 1 is a process chart for explaining a first embodiment of a method of manufacturing an optical waveguide according to the present invention. In this figure, first, in the waveguide base material manufacturing process (FIG. 1A), the cladding layer member 6 made of SiO ₂ and the SiO ₂
A waveguide base material is manufactured by heat-sealing a core layer member 7 (having a member thickness L) having a refractive index increased by doping Ge into ₂ with Ge.

Subsequently, in the base material stretching step (FIG. 1 (b)), the produced waveguide base material is stretched while being heated in the longitudinal direction (the direction of the arrow in the figure), and the core layer is formed. Stretching is performed until the film thickness of the member 7 reaches a desired film thickness L ′ (here, the film thickness satisfies the relationship of L / L ′ = γ (> 1)).

Then, the waveguide base material thus stretched in the base material processing step (FIG. 1 (c)) is cut in a direction perpendicular to the longitudinal direction with a thickness W, and finally a clad forming step ( 1 (d)) is a cross section of the base material 8 cut to have the thickness W, and the cladding layer 6 is adhered to the two surfaces where the core layer is exposed from the direction of the arrow in the drawing. An optical waveguide as shown in (e) is manufactured.

Next, a method of manufacturing an optical coupler as an optical waveguide (second embodiment) will be described with reference to FIG.

In this figure, first, in the step of producing the waveguide base material (FIG. 2A), as in the first embodiment described above, S
A cladding layer member 6 made of io ₂ and a core layer member 7 having a refractive index increased by doping Ge into SiO ₂
(The member thickness is L) is fixed by a frame member 9 made of the same material as the clad layer member 6, and heat fusion is performed to produce a waveguide base material.

Subsequently, in the base material stretching step (FIG. 2 (b)), the produced waveguide base material is stretched while being heated in the longitudinal direction (the direction of the arrow in the figure), and the core layer is formed. Stretching is performed until the film thickness of the member 7 reaches a desired film thickness L ′ (here, the film thickness satisfies the relationship of L / L ′ = γ (> 1)).

Then, the waveguide base material thus stretched in the base material processing step (FIG. 2C) is cut in a thickness W in the direction perpendicular to the longitudinal direction, and then, the frame member 9 is obtained. The outer peripheral portion of the stretched waveguide base material is ground, and finally the core layer is exposed in the cross section of the base material 8 cut to the thickness W in the clad forming step (FIG. 2D). The cladding layer 6 is adhered to the two surfaces in the direction indicated by the arrow in the drawing to manufacture an optical waveguide as shown in FIG.

The waveguide base material 8 cut to the thickness W is used.
After cutting, the outer peripheral portion of the base material 8 corresponding to the frame member 9 may be ground, and the optical coupler manufactured in this way corresponds to the core layer thereof as shown in FIG. 2 (f). The portion is used by being joined to each end face of the optical fiber 10.

Next, a method of manufacturing an optical branching module as an optical waveguide (third embodiment) will be described with reference to FIGS. 3 and 4.

In this figure, first, in the step of producing the waveguide base material (FIG. 3A), SiO ₂ is doped with, for example, F (fluorine) as an element for lowering the refractive index, and a material whose refractive index is reduced is clad. Used as the layer member 11, the clad layer member 11 is fixed by the frame member 9 and heat-fused with a space (gap) 12 between the members to produce a waveguide base material.

When a space is provided in the clad layer member 11 as described above, F on the surface of the clad layer is volatilized into the air during heat fusion, so that the clad layer member 1 as shown in FIG.
A fused region having a larger refractive index (smaller F concentration) than that of No. 1 is formed, and as a result, this fused region of about 5 μm (portion indicated by hatching in the figure) becomes the core layer.

Subsequently, in the base material drawing step (FIG. 3 (b)), the produced waveguide base material is lengthwise (FIG. 3).
Stretching while heating in (b), the direction of the arrow),
The core layer member 7 is stretched until it has a desired film thickness L '.

Then, the waveguide base material thus stretched in the base material processing step (FIG. 3 (c)) is cut in a direction perpendicular to the longitudinal direction to a thickness W, and finally a clad forming step ( 3 (d)) is a cross-section of the base material 8 cut to this thickness W, and the cladding layer 6 is adhered to the two surfaces where the core layer is exposed from the direction of the arrow in the drawing. An optical waveguide as shown in (e) is manufactured.

The waveguide base material 8 cut to the thickness W is used.
After cutting, the outer peripheral portion of the base material 8 corresponding to the frame member 9 may be ground.

[0028]

As described above, according to the present invention, a substantially circular waveguide base material having a similar structure in a cross section perpendicular to the longitudinal direction is manufactured (waveguide base material manufacturing step), This waveguide base material is heated and stretched in the longitudinal direction until it has a predetermined core layer width (base material stretching step), and the stretched waveguide base material is cut at a predetermined thickness in a direction orthogonal to the longitudinal direction. Or, after cutting, polishing (base material processing step) and adhering the clad layer to the two cut surfaces of the cut base material where the core layer is exposed (clad forming step), the same Since the refractive index can be made uniform by forming a plurality of core parts from the base material, it is easy to control the refractive index, and there is an effect that the etching step required in the conventional manufacturing method becomes unnecessary. .

[Brief description of drawings]

FIG. 1 is a process drawing for explaining a first embodiment of a method of manufacturing an optical waveguide according to the present invention.

FIG. 2 is a process drawing for explaining the second embodiment of the method of manufacturing an optical waveguide according to the present invention.

FIG. 3 is a process drawing for explaining the third embodiment of the method of manufacturing an optical waveguide according to the present invention.

FIG. 4 is a drawing for explaining the state of the core layer in the third embodiment of the method of manufacturing an optical waveguide according to the present invention.

FIG. 5 is a process chart for explaining a conventional method for manufacturing an optical waveguide.

[Explanation of symbols]

6, 11 ... Clad layer member, 7 ... Core layer member, 8 ... Waveguide base material after cutting, 9 ... Frame member, 12 ... Space (gap).

Claims (5)

[Claims] 1. An optical waveguide comprising a clad layer and a core layer, wherein light is confined and guided in the core layer, the member comprising the clad layer and the core layer,
A waveguide base material manufacturing step of manufacturing a waveguide base material in which a structure of a cross section perpendicular to the longitudinal direction has a similar shape; A base material drawing step of making a layer width a predetermined width; a base material processing step of cutting the drawn waveguide base material with a predetermined thickness in a direction orthogonal to the longitudinal direction; and the predetermined thickness. A method of manufacturing an optical waveguide, comprising: a clad forming step of adhering a clad layer to two cut surfaces of a base material cut into pieces and exposing a core layer. 2. The optical waveguide according to claim 1, wherein in the step of producing the waveguide base material, the waveguide layer base material is produced by fixing the clad layer member and the core layer member and heat-sealing them. Manufacturing method. 3. In the step of producing the waveguide base material, a clad layer member made of SiO ₂ doped with an element that lowers the refractive index is fixed in advance with a space corresponding to the core layer as a space, and heat fusion is performed. 2. The method of manufacturing an optical waveguide according to claim 1, wherein the waveguide base material is manufactured by the following method. 4. The method of manufacturing an optical waveguide according to claim 1, wherein the cross-sectional outer peripheral shape of the waveguide base material is substantially circular. 5. The base material processing step comprises, after cutting the stretched waveguide base material, polishing an outer peripheral portion of the base material cut into a predetermined thickness. Manufacturing method of optical waveguide.