JPH02198402A - Manufacture of non-linear optical waveguide - Google Patents

Abstract

PURPOSE:To easily manufacture high-value electron ion lead-in glass by forming a thin film on a crystal substrate with a sol-gel method by using an organic compound containing a hihg-value electron ion, heating the thin film and vitrifying it, and thereafter, converting it to a pattern, and obtaining a transparent waveguide layer by executing an ion exchange or a diffusion. CONSTITUTION:The group IVa elements of a periodic table such as Ti, Zr, the group IIIa elements such as Y, La, Ce, Nd, or an organic compound containing a metallic element which becomes a high-value electron ion of Nb, the organic compound of a glass material which becomes a network former and the organic compound of a glass material which becomes a modified oxide are gelatinized by a sol-gel method, and this gel is applied onto a crystal substrate 1, while its viscosity is low enough. The obtained thin film is heated and vitrified, and a high-value electron ion lead-in type thin film-like glass (glass thin film) 2 is obtained on the crystal substrate 1. This glass thin film 2 is converted to a pattern, and also, by executing an ion exchange or diffusion, the part converted to the pattern is formed as a transparent waveguide layer 3 and an waveguide 4 is obtained. In such a manner, high-value electron ion lead-in glass can be easily manufactured.

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention relates to a method for manufacturing a guiding waveguide that is suitably used as an all-optical optical switch using an optical nonlinear effect, and particularly relates to a method for manufacturing a guiding waveguide that is suitably used as an all-optical optical switch using an optical nonlinear effect. The present invention relates to a method of manufacturing a nonlinear optical waveguide having a waveguide layer.

"Prior Art and Its Issues" Recently, optical switches that use the photoelectric effect have been widely studied, but such optical switches have various problems in bringing electricity into optical circuits. Furthermore, due to reasons such as insufficient response speed, they have not yet been used as arithmetic elements in optical computers and the like.

By the way, as a nonlinear material used for all-optical optical switches or arithmetic element materials, it is desirable to have a large nonlinear effect and quick response, a high damage limit, and a wide transmission area, and the materials currently being researched are desirable. Known examples include semiconductor materials, glass materials, and organic materials. In particular, materials with large nonlinearity include semiconductors with a quantum well structure, organic nonlinear materials, and semiconductor-doped glass materials. However, although semiconductor materials exhibit large nonlinearity, they exhibit a response speed that is considerably lower than the required response speed due to their high absorption coefficients, and they also have the problem of large thermal dependence.

In addition, as glass materials, semiconductor-doped glass materials, high-value electron ion implantation glass materials, etc. are known.In particular, high-value electron ion implantation glass materials have relatively small nonlinearity, but have high-speed response, low loss, and high damage resistance. It is known to have excellent properties such as.

To obtain such high-value electron iontophoretic glass materials,
Usually, it is produced by vitrifying glass component-based powder in a platinum crucible, but the temperature range in which it can be vitrified is narrow due to differences in the melting points of each component, making its production extremely difficult. In addition, in order to manufacture waveguides from this material, it is common to create a wafer from glass bulk and perform ion exchange on it to form the waveguide, but this method requires a large optical circuit (leading waveguide). It is difficult to form, and even the optical circuit obtained has a large loss due to precipitation of crystals such as Ti and Zr. Furthermore, in this method, ions such as heavy metals may be mixed in as impurities, which may increase optical damage.

This invention was made in view of the above circumstances, and its purpose is to easily manufacture a waveguide layer made of high-value electron ion-implanted glass, and also to be able to manufacture large-sized optical circuits. An object of the present invention is to provide a method for manufacturing an optical circuit with low loss and excellent damage resistance.

"Means for Solving the Problems" In the method for manufacturing a nonlinear optical waveguide of the present invention, an element of Group 1 Va of the periodic table, an element of Group 1 [La of the periodic table, or Nb
A thin film is formed on a crystal substrate by a sol-gel method using an organic compound, then the thin film is heated to vitrify it, the glass thin film is then patterned, and then ion exchange or diffusion is performed to form the above pattern. The solution to the above problem was to make the removed part a transparent waveguide layer.

An example of this invention will be described in detail below.

First, elements of Group 1 Va of the periodic table such as Ti and Zr, Y, and L
An organic compound containing an element of group IIIa of the periodic table such as a, Ce, or Nd or a metal element that becomes a so-called high-electron ion such as Nb is prepared. Examples of this organic compound include Ti(o C21-15)4, Zr(OCT4
3) Alkoxy compounds such as 4 and N b (05Hs)
Various materials can be used depending on the metal, such as s, T1(OH3)4, etc. In addition to the above-mentioned organic compounds, an organic compound of a glass material to serve as a network former and an organic compound of a glass material to serve as a modified oxide are also prepared. Here, oxides such as S io IA 1t03 are used as the material for the network former, and NatO, B to 3. MgO,Kt
Examples include O, CaO, and the like.

Next, the above-mentioned organic compound containing a metal element that becomes the high-value electron ion, the organic compound of the glass material that becomes the network former, and the organic compound of the glass material that becomes the modified oxide are gelled by the sol-gel method. Apply the gel onto the crystal substrate while the viscosity is sufficiently low. Here, as the crystal substrate, T io 2 (2, 58), S rT
io 3 (2,38), P bM 005 (2,31
).

B G O (2,55), L iN bo 3 (2,
25), L iT ao 3(2,18)A, I N
(2,18), Y G G (1,94), Y A G
(1,84), B e.

Materials such as (1,72) are used. Note that the numerical value in parentheses after the above material name indicates the refractive index.

To carry out the sol-gel method, first the above-mentioned organic compounds are dissolved in an organic solvent such as benzene, and then water is added dropwise over a sufficient period of time to convert each of the above-mentioned organic compounds into oxides through hydrolysis. gelatinizes by Thereafter, the resulting gel is coated onto a crystal substrate while the gel has a suitable viscosity for coating. When selecting multiple types of organic compounds here, the combination of the thin film glass obtained from these organic compounds and the crystal substrate material, that is, the difference in refractive index between the thin film glass and the crystal substrate, and the difference between the thin film glass and the crystal substrate. It is necessary to consider differences in reactivity and melting temperature.

Next, the thin film obtained from the gel was heated to vitrify it,
As shown in FIG. 1, a so-called high-electron ion introduction type thin film glass (hereinafter referred to as a glass thin film) is placed on a crystal substrate 1.
Get 2. The heating here is adjusted appropriately depending on the organic compound used, but the heating is at a low temperature (100°C) for drying the gel.
℃) and high temperature (950℃) for vitrification.
It is desirable to carry out the process in two stages: heating (degree). Further, in this case, when heating at high temperature, it is necessary to adjust the temperature so that a reaction between the thin film and the crystal substrate does not occur.

Thereafter, the obtained glass thin film 2 is patterned and further subjected to ion exchange or diffusion, and as shown in FIG. 2, a waveguide 4 is obtained by using the patterned portion as a transparent waveguide layer 3. For patterning here, various techniques normally used for producing waveguides can be used, such as sputtering Ti and then etching it into a desired pattern, or masking a glass thin film and forming a pattern. A method of sputtering or vapor depositing Ti can be adopted. In this case, when producing the waveguide layer, for example, water vapor is introduced into an electric furnace and heated at 100° in this water vapor atmosphere.
A waveguide layer is obtained by diffusing Ti by a thermal diffusion method using heating at about C to make the patterned portion of the glass thin film transparent. In addition, to create a waveguide layer by ion exchange,
For example, a glass thin film is masked and patterned, and this is
It can be made transparent by a thermal ion exchange method or an electric field ion exchange method using a neutral salt such as lNO3.

The waveguide thus obtained has much lower loss than a waveguide using expensive electron-ion-implanted glass produced by the conventional fused glass method.

"Examples" The present invention will be explained in more detail below using Examples.

'riO2-Nb20a-25iOt-8203-Li
Ti (OG tHs) is used as a material for producing a high-electron ion introduction type glass thin film having a composition of 2O.
t.

Nb(C5H5)3. S i (OCH3)4. B (O
Each of CH3)3°L i (S CeH8) was prepared, each dissolved in a solvent such as benzene, and then mixed to obtain a desired composition ratio. In addition, L i N b Os was prepared separately as a crystal substrate.

Next, water was added dropwise to the glass material dissolved in the above solvent over a sufficient period of time to form a gel.

Here, the reaction conditions were that the temperature of the glass material dissolved in the solvent was 45° C., and the reaction time was 6 hours.

Next, the obtained gel was applied onto the crystal substrate before its viscosity increased significantly. Furthermore, after drying the applied gel at 100°C for 4 hours, the temperature was raised to 950°C to obtain a glass thin film.

Next, Ti was sputtered onto this glass thin film to a thickness of 90 mm.
After that, a pattern with a width of 7 μm was formed, and then Ti was diffused by heating at 1000° C. in a steam atmosphere to form a waveguide layer in the glass thin film to obtain a waveguide.

When the waveguide loss of the obtained waveguide was investigated, it was found to be 0.2 dB.
/cm, resulting in a much lower loss than a waveguide using expensive electron-ion-implanted glass produced by the conventional molten glass method.

Furthermore, when the nonlinear refractive index of the glass thin film produced on the crystal substrate was examined, it was found to be 5 x 10-8/W.

"Effects of the Invention" As explained above, the method for manufacturing a nonlinear optical waveguide of the present invention uses an organic compound containing high-value electron ions.
A thin film is formed on a crystal substrate by a gel method, the thin film is heated and vitrified, and then patterned and ion exchange or diffusion is performed to obtain a transparent waveguide layer.
It is possible to easily produce a high-value electron ion-implanted glass by solving manufacturing problems caused by differences in melting points of each component constituting the high-value electron ion-implanted glass, and therefore the present invention can be carried out using existing wafer processes. Therefore, it has various manufacturing advantages such as reduced production costs, and the resulting waveguide has much lower loss than conventional waveguides. Furthermore, since it is possible to easily produce high-value electron ion-implanted glass,
It is also possible to fabricate a large leading waveguide (optical circuit), and even in the resulting optical circuit, precipitation of crystals of high-value electron ions is prevented, resulting in sufficiently low loss.

[Brief explanation of the drawing]

FIGS. 1 and 2 are perspective views for explaining an example of the method for manufacturing a nonlinear optical waveguide according to the present invention in the order of steps. l...Crystal substrate, 2...Glass thin film, 3...
... Waveguide layer, 4... Waveguide.

Claims (1)

[Claims] A thin film is formed on a crystal substrate by a sol-gel method using an organic compound of a group IVa element of the periodic table, a group IIIa element of the periodic table, or Nb, and then the thin film is heated to vitrify it. A method for manufacturing a nonlinear optical waveguide, which comprises patterning a glass thin film and then performing ion exchange or diffusion to make the patterned portion a transparent waveguide layer.