JPS58118606A - Production of optical waveguide - Google Patents

Abstract

PURPOSE:To make an optical waveguide stable thermally and mechanically and low in loss and to improve the coupling efficiency thereof to optical fibers by forming said waveguide into a sectional shape of roughly a circular shape. CONSTITUTION:When a substrate 4 provided with a thin film layer 1 of aluminum, a thin film layer 2 of silver, an anode electrode 3 consisting of chromium and a cathode electrode 3' of aluminum by vacuum deposition is heated to glass deforming temp. or below with a heater 5 and the respective electrodes are removed after applying an electric field thereto the diffuse silver ions into the substrate 4, a high refractive index part 6 having a section of a semicircular shape is formed in the substrate 4. The substrate 4, and a substrate 7 contg. a thin film layer 9 of silver and an anode electrode 10 consisting of chromium are press stuck by using jigs 8 for press sticking in such a way that the cathode 10 and the anode 10 are located mutually on the outer sides. Both substrates are heated, and an electric field is applied thereto to force the part 6 into the substrate 4. At the same time, the silver of the layer 9 is ionized and is penetrated into the substrate 7. As a result, the high refractive index part 6' having a sectional shape of a roughly circular shape is obtained in the substrate 4, and said part acts as an optical waveguide.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a guiding waveguide formed on a substrate.

Optical waveguides formed on substrates play an important role in making optical circuits smaller, more integrated, and improving reliability. This guiding waveguide basically has a structure in which a core portion having a relatively high refractive index is covered with a cladding portion having a relatively low refractive index. Conventionally, as a method for manufacturing such an optical waveguide, a method is known in which an optical waveguide is formed only by a step of diffusing metal ions for forming a high refractive index layer into a substrate. However, in this method, as shown in FIG.
Since the cross-sectional shape of the optical fiber is semicircular, the coupling efficiency with the optical fiber is low.

An object of the present invention is to eliminate the above-mentioned drawbacks and provide a method for manufacturing an optical waveguide with high coupling efficiency with an optical fiber.

According to the present invention, I! a first step of forming a high refractive index portion by selectively infiltrating the first substrate with metal ions that increase the refractive index of the first substrate when permeated into the first substrate; The above process has been completed! ! a second step of press-bonding a second substrate made of glass to the side of the first substrate on which the high refractive index portion is formed; The high refractive index portion formed on the first substrate is formed by performing electric field diffusion to cause the cations to permeate into the first substrate. A method for manufacturing an optical waveguide is obtained, which includes a third step of embedding the optical waveguide inside the substrate J1.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

W&2 Figures (a) to (d) are process diagrams showing one embodiment of the method for manufacturing an optical waveguide according to the present invention. As shown in FIG. 2 (31), first, an aluminum thin film layer 1 with a pattern formed by a lift-off method, a silver thin film layer 2 with a thickness of about 1 to 10 μm, a positive electrode 3 made of chromium, and an aluminum A first substrate 4 made of BK7 glass with a thickness of 1 to 3 sll, on which a cathode 3' consisting of 2 to 300V/
An electric field of sm is applied to diffuse silver ions into the first substrate 4. After the diffusion, the aluminum thin film layer 1, the positive electrode 3, the negative electrode 3', etc. are removed. Board 4 of said I81
As a result of diffusion, a high refractive index portion 6 having a semicircular cross section is formed as shown in Figure W&2 (b).

Next, as shown in FIG. 2(C), a cathode 10 made of aluminum is newly formed on the side where the high refractive index portion 6 is not formed by vacuum evaporation on the first substrate 4. and a positive electrode 10' made of BK7 glass with a thickness of 1 to 3 fl, and on one side thereof a thin film layer 9 of silver with a thickness of about 1 to 10 μm and a positive electrode 10' made of chromium are sequentially formed by vacuum evaporation. 9. The second substrate 7 is attached to the negative electrode 1 using a crimping jig 8.
0 and the positive electrode 10' are pressed together so that they are on the outside of each other, and are heated using a heater 5 to below the glass strain temperature of about 250°C to 550°C, and an electric field of 2 to 300 V/- is applied. By applying the voltage, sodium ions, potassium ions, etc., which are cations of the modified oxide contained in the second substrate 7, are allowed to permeate into the first substrate 4. The formed high refractive index portion 6 is pushed into the first substrate 4. At this time, at the same time, the silver in the silver thin film layer 9 is ionized and permeates into the second substrate. As a result, as shown in Figure 2 (dlK), the first
A high refractive index portion 6' having a substantially circular cross-sectional shape is obtained inside the substrate 4. This leads to the optical waveguide.

Since the optical waveguide obtained in this example has a #1 approximately circular cross-sectional shape, it is easier to connect to an optical fiber than a conventionally produced optical waveguide with a semicircular cross-sectional shape. Excellent in terms of coupling efficiency.

An embodiment of the present invention has been described above. Here, although silver ions were used as metal ions in this example, thallium ions, lithium ions, etc. may also be used. Further, although BK7 glass was used as the glass, soda lime glass or the like may also be used.

Finally, to enumerate the characteristics of the optical waveguide made using the manufacturing method according to the present invention, it is possible to obtain an optical waveguide with a nearly circular cross-sectional shape, so that the coupling efficiency when connecting with an optical fiber is good. Since the formed optical waveguide is formed inside the substrate, the optical waveguide loss is small and it is thermally and mechanically stable.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a light traveling waveguide made by the conventional method;
Figures (al to (d)) are process diagrams showing an example of the method for manufacturing an optical waveguide according to the present invention. 11... Substrate, 12... Optical waveguide, 1
...Aluminum thin film layer, 2...Silver thin film layer, 3...Positive electrode, 3'...Nathode, 4...・Substrate, 5... Heater, 6
...High refractive index section, 7...Substrate, 8...
...Jig for crimping, 9... Thin film layer of bride, 10
......Cathode electrode, 10'...Positive electrode. half a game

Claims (2)

[Claims] (1) A first step in which a high refractive index portion is formed by selectively permeating a metal ion, which increases the refractive index of the first substrate when permeated into the first substrate, into a substrate of Ill such as glass. and the above-mentioned I! which has undergone the above-mentioned first step. A second step of press-bonding a 1g2 substrate made of glass to the side of the first substrate on which the high refractive index portion is formed, and using cations of the modified oxide contained in the second substrate as a diffusion source. The high refractive index portion formed on the substrate @1 by performing electric field diffusion to permeate cough cations into the first substrate is
a third step of embedding the optical waveguide inside the substrate. (2) Before the step of $2, the first
After forming a thin film layer containing at least one kind of metal on the side not in contact with the substrate and performing the second step, metal ions of the metal are added to the WjI2 in the third step.
2. The method of manufacturing a guiding waveguide according to claim 1, wherein the step of infiltrating into the substrate is performed simultaneously.