JPS58190903A - Formation of optical waveguide - Google Patents

Abstract

PURPOSE:To form a diffusion layer of an optical waveguide to a dielectric substrate, by irradiating the optical energy to the surface of the transparent dielectric substrate after forming a metallic thin film for optical waveguide in order to produce a reaction between the metallic thin film and the dielectric substrate. CONSTITUTION:A metallic thin film 12 is formed on the surface of a dielectric substrate 11 and at the part where an optical waveguide is formed. Then the light energy is irradiated from a light source 14 through the rear side of the substrate 11. The light energy is not virtually absorbed by the substrate and absorbed by the film 12. Then the heat is selectively generated to produce a reaction between the film 12 and the substrate 11. As a result, a metal (e.g., titanium) is diffused into the substrate 11. The absorbing coefficient of the optical energy of <=600nm wavelengths increases at the metal diffused part. The diffusion is accelerated to form a diffusion layer 16. Therefore it is possible to form an optical waveguide in a short time without heating up the entire part of the substrate 11 but with the local heating which is carried out by making use of the selective absorption of the light energy.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of forming an optical waveguide by diffusion of metal impurities.

A conventional method for forming an optical waveguide will be explained with reference to FIG.

In Figure 1, 1 is, for example, lithium niobate (L
2NbOs), and first,
A photoresist (for example, AZ1
350) Form a reverse pattern of the optical waveguide according to 2. Next, as shown in FIG. 1(B), a metal thin film such as titanium 3 is deposited over the entire surface. Next, by removing the photoresist 2 by soaking it in, for example, acetone, the photoresist 2 shown in FIG.
As shown in FIG. 3, the titanium 3 is left only in the portion where the optical waveguide will be formed. After that, heat treatment furnace (970°C)
Heat treatment for ~7 hours. When this heat treatment is performed, titanium from the titanium 3 is diffused into the dielectric substrate 1 by about 0.5 to 2 μm, and a diffusion layer 4 is formed as shown in FIG. The refractive index of this diffusion layer 4 is about 1% smaller than that of the dielectric substrate, such as a layer of lithium niobate.
It can function as an optical waveguide.

However, with this conventional method, the total number of
There was a drawback that it required heat treatment to be heated to 0° C. and for a long time of 5 to 7 hours.

This invention was made in view of the above points, and is based on local heating (
An object of the present invention is to provide a method for forming an optical waveguide that can form a diffusion layer (optical waveguide) in a short time using local heat generation.

An embodiment of the present invention will be described below with reference to FIG. In FIG. 2, reference numeral 11 denotes an optically transparent dielectric substrate such as lithium niobate, and a metal thin film 1 made of titanium, for example, is coated only on the surface where an optical waveguide is to be formed.
2 is formed.

The dielectric substrate 11 is supported on the support stand 13 with the front and back sides reversed so that the front side of the tab is located on the support stand 13 side. Reference numeral 14 denotes a light source consisting of, for example, an infrared lamp, which irradiates the dielectric substrate 11 with light energy from its surface side. 15 is a lens system interposed between the light source 14 and the dielectric substrate 11.

That is, in the embodiment, after the metal thin film 12 is formed on the surface of the dielectric substrate 11 at a portion where an optical waveguide is to be formed, the surface of the dielectric substrate 11 is irradiated with light energy from the light source 14 . Then, the light energy is hardly absorbed by the dielectric plate 11 and is completely absorbed by the metal thin film 12. Therefore, the metal # film 12 selectively generates heat. Then, due to this heat generation, a reaction occurs between the multimetal thin film 12 and the dielectric substrate 11 , and metal (yt or titanium) is diffused from the metal thin film 12 into the dielectric substrate 11 . When metal is diffused into the brocade one-piece substrate 11, the absorption coefficient of light energy having a wavelength of 600 nm or less increases in the portion where the metal is diffused. Therefore, not only the metal thin film 12 but also the diffusion portion generates heat due to the absorption of light energy, promoting diffusion, and eventually a diffusion layer 16 is formed on the dielectric substrate 11 as shown in FIG. .

As is clear from the above embodiments, in the method of the present invention, a reaction is caused between the metal thin film and the dielectric substrate by irradiating light energy, and the diffusion layer as an optical waveguide is formed into a dielectric material. formed on the body substrate.

According to the method of the present invention, an optical waveguide can be formed in a short time by utilizing selective absorption of optical energy without heating the entire dielectric substrate. .

[Brief explanation of drawings]

FIG. 1 is a sectional view for explaining a conventional method for forming an optical waveguide, and FIG. 2A is a diagram for explaining an embodiment of the method for forming a leading waveguide according to the present invention. 11... Dielectric substrate, 12... Metal thin film, 14...
- Light source, 16...diffusion layer. Patent Applicant Oki Ketsu Kogyo Co., Ltd. Figure 1 Procedural Amendment September 1980 311 Commissioner of the Patent Office Kazu Wakasugi Failure 1, Indication of the Case 1982 Patent Application No. 73312 2 Name of the invention Formation of optical waveguide Method 3: Relationship with the person making the amendment Patent applicant (029)
Oki Electric Industry Co., Ltd. 4, Agent 5, Date of amendment order: 1939, Month, Day (voluntary) 6, Scope of claims of the specification to be amended and Detailed explanation of the invention column 7, Contents of the amendment attached. Street (1) "Claims 2" in the specification are corrected as shown in the attached sheet. (2) Delete “Impurities” on page 1, line 12 of the specification. (3) Same page 1 line 16 r L2NbO, J to rLiNbO
Correct it to mJ. 2. Claims After a thin metal film is formed on one surface of an optically transparent dielectric substrate in a portion where an optical waveguide is desired to be formed, a reaction between the thin metal film and the dielectric substrate is caused by irradiating light energy. 1. A method for forming an optical waveguide, comprising: forming a diffusion layer as an optical waveguide on a dielectric substrate.

Claims (1)

[Claims] After forming a metal thin film on one side of an optically transparent dielectric substrate in the area where an optical waveguide is to be formed, a reaction between the metal thin film and the dielectric substrate is caused by irradiation with light energy to form a guiding waveguide. A method for forming a leading waveguide, which comprises forming a diffusion layer on a dielectric substrate.