JPH01191804A - Optical waveguide and its manufacture - Google Patents

Abstract

PURPOSE:To eliminate a shape failure of the reflecting surface of an optical waveguide and to decrease a transfer loss by pouring a transparent substance whose melting point is lower than that of a substrate into a groove provided on the substrate, and fixing and forming it. CONSTITUTION:A paraffin layer 2 is formed by applying uniformly paraffin which has been melted by a solvent, by spin coating onto a substrate for forming an optical waveguide of a plate of quartz glass, and solidifying it. Subsequently, a mask 3 which has cut out a pattern 31 of the optical waveguide in a plate of Cu, etc., is placed on the layer 2, and next, a groove 4 corresponding to the pattern is engraved by pouring a solution of hydrogen fluoride, the paraffin is melted and the mask 3 is removed and washed, and low alkali glass 5 whose melting point is lower than that of the substrate 1 is heated and melted, and poured into the groove 4. Subsequently, by slow cooling, the glass 5 is solidified and an optical waveguide is formed. The surface of an optical waveguide 7 which has been formed in such a way is extremely smooth by surface tension of molten glass at the time of casting of the glass 5, and accordingly, a transfer loss of light is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of forming an optical waveguide on a substrate as an optical communication member.

(Prior art) Conventional optical waveguides are manufactured by coating a photoresist on a SiO□ substrate, exposing the mask with ultraviolet rays on which the optical waveguide pattern is drawn, and baking the optical waveguide pattern. When the resist is washed and developed with water, only the part of the optical waveguide pattern that was not exposed to light is washed away, leaving a groove in the optical waveguide part.Next, low alkali glass is deposited on the substrate by sputtering method, etc., and then the photoresist is When removed with a solvent, only the part of the low-alkali glass deposited directly on the substrate remains in the groove, and the other parts are peeled off together with the photoresist.As a result, the light guide by the low-alkali glass corresponding to the pattern of the groove remains. A wave path will be formed on the substrate.

[Problem to be solved by the invention]

However, according to such conventional methods, sputtering takes a long time, and it takes a very long time to form a large optical waveguide with a thickness of 10 μm or more, resulting in extremely low working efficiency.

It is an object of the present invention to solve such problems and form an optical waveguide with a large thickness in a short time.

[Means to solve the problem]

The present invention forms a large optical waveguide in a short time by directly pouring low-melting glass into a groove formed on a substrate of an optical waveguide member.

〔Example〕

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

FIG. 1 is an explanatory diagram of the fourth manufacturing process of the optical waveguide of the present invention.

(1) 1 is a substrate for forming an optical waveguide made of, for example, a flat plate of quartz glass, on which paraffin dissolved in a solvent is applied uniformly by spin coating and solidified to form a paraffin layer 2 [ See Figure 1(a)].

(2) Next, on this paraffin N2, a mask 3 with an optical waveguide pattern 31 cut out on a copper or stainless steel plate
Place the mask on the mask and apply a solvent to melt and remove the paraffin from the cut-out part of the mask (see Figure 1, etc.).

Therefore, in the quartz glass substrate 1, only the portion forming the optical waveguide is exposed, and the rest is covered with the paraffin layer 2.

(3) Then, by pouring a hydrogen fluoride solution on top, the exposed glass surface is melted and grooves 4 corresponding to the cutout pattern of the mask are carved. [See Figure 1 (C)].

(4) The paraffin is dissolved with a suitable alkaline solvent, the mask is removed and washed, and low alkali glass 5 having a melting point lower than that of the quartz glass substrate 1 is heated and melted and poured into the groove 4.

At this time, it is desirable that the glass plate serving as the substrate 1 be heated to a high temperature that does not melt itself.

(5) Thereafter, by slowly cooling and solidifying the low melting point glass 5, the low melting point glass portion can be formed as an optical waveguide.

[See Figure 1(d)].

FIG. 2 is a partially enlarged sectional view of the optical waveguide formed in this manner. The surface of the optical waveguide 7 formed in the mask groove 4 of the substrate 1 is extremely smooth due to the surface tension of the molten glass when the low melting point glass is poured in step 4.

Therefore, since there is no disturbance in the shape of the optical waveguide surface, which is the biggest cause of optical transmission loss in the optical waveguide, the optical transmission loss is reduced and a relatively large optical waveguide can be formed in a short time using simple steps.

FIG. 3 shows another embodiment in which, instead of melting and pouring the low melting point glass 5 in the previous embodiment, a low melting point glass powder 8 is poured into the mask groove carved on the substrate, and then, for example, An optical waveguide is obtained by melting only the low-melting point glass powder using a heating means such as a gas burner and then slowly cooling it to solidify it.

FIG. 4 is an explanatory diagram regarding a method for removing bubbles in an optical waveguide formed according to the present invention.

Generally, optical waveguides are manufactured by avoiding contamination of foreign matter in the scratched optical waveguide in order to reduce optical transmission loss, but in particular light scattering due to air bubbles in the optical waveguide.

Loss due to absorption and the like is large, and these bubbles pose a major obstacle to optical waveguides.

Below, the means for removing bubbles in the optical waveguide formed according to the present invention will be explained.

7 is an optical waveguide formed according to the present invention in a mask pattern groove on a glass substrate 1 made of quartz or the like, and 11 is a heating means such as a gas burner.

To remove the bubbles 10, 10.10 in the optical waveguide 7,
The optical waveguide 7 is heated from below the substrate 1 using a gas burner 11 with a small flame. Then, the optical waveguide 7 made of low melting point glass
(This liquefied portion is designated by 9).

Some of the bubbles contained in the liquefied portion 9 escape into the atmosphere from the surface.

Therefore, by moving the heating means 11 such as a gas burner in the direction of the arrow, the liquefied portion 9 also moves in the direction of the arrow.
The remaining air bubbles that did not escape from the surface into the atmosphere move together with the liquefied portion as the burner moves.

Therefore, the bubbles in the optical waveguide will eventually gather at the final end of the burner movement, so by cutting the part where the bubbles are concentrated at the end of the optical waveguide together with the substrate, the bubbles in the optical waveguide can be completely removed. At the same time, the surface of the optical waveguide becomes smoother due to the surface tension of the low-melting glass during heating and melting, so there is no optical transmission loss due to poor surface shape of the optical waveguide, and an extremely good optical waveguide can be obtained.

〔Effect of the invention〕

In the present invention, an optical waveguide is formed by filling a transparent low-melting substance into a groove cut on a glass substrate and melting and solidifying it. Therefore, a large optical waveguide can be formed in a short time with a simple process, and an optical waveguide can be formed. When the surface of the waveguide is melted and solidified, the surface tension of the optical waveguide forming material automatically forms an extremely smooth reflective wall, which reduces light transmission loss due to poor shape of the reflective surface of the optical waveguide.

In addition, the bubble removal operation can be repeated as many times as necessary for the optical waveguide once formed using a simple heating means such as a burner, so the light transmission effect can be increased as needed and the optical waveguide can be formed very easily. Since scratches and distortions can be corrected, the final defective rate of the product can also be significantly reduced.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the manufacturing process of the optical waveguide of the present invention, Fig. 2 is a partially enlarged sectional view of the optical waveguide formed by the method of the present invention,
FIG. 3 is an explanatory diagram of the process of forming an optical waveguide according to another embodiment,
FIG. 4 is an explanatory diagram of a method for removing bubbles from an optical waveguide formed according to the present invention. 1... Substrate 4... Groove 5... Low melting point transparent material 7... Optical waveguide 11... Heating means patent applicant Teijin Seiki Co., Ltd. (a) (b) (C) \ (d )6 Figure 2 Figure 3

Claims (3)

[Claims] (1) A method for manufacturing an optical waveguide, which comprises pouring a transparent substance having a melting point lower than that of the substrate into a groove provided on the substrate and solidifying the substance. (2) Air bubbles in an optical waveguide are removed by moving along the optical waveguide formed by the method according to claim 1 while partially heating and remelting the optical waveguide. Removal method. (3) An optical waveguide manufactured by the method according to claim 1 or 2.