JPS6167838A - Waveguide type optical switch - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical circuit element, and particularly to an optical switch having crossed waveguides.

Optical switches currently in practical use generally use mechanical switching methods such as moving mirrors, making it difficult to miniaturize and integrate.
Adjustment technology is required.

The present inventors have previously discovered that compact, low-voltage driving is possible with a crossed waveguide optical switch formed in an electro-optic crystal. [Unexamined Japanese Patent Publication No. 59-060425 Optical Switch] [Prior Art] Fig. 4 is a schematic diagram of the main part for explaining the waveguide structure of a conventional crossed waveguide type optical switch. A band-shaped titanium thin film layer 2 is formed so as to intersect on the surface of a substrate 1 made of electro-optic crystal such as LiNbO:+), and the titanium thin film layer is heat-treated at, for example, 1040"C for 5 hours. 2 diffuses into the substrate 1, and a waveguide 3 having a higher refractive index than the substrate 1 is formed.

FIG. 5 is a schematic diagram of the main parts for explaining the structure of a conventional crossed waveguide type optical switch, in which a rectangular electrode 4 is placed at the intersection of two optical waveguides, with its long side facing the light incident side of the two leading waveguides. Parallel to the line connecting the apex P of the intersection angle formed by the edges of the parts 31 and 32 and the apex Q of the intersection angle formed by the edges of the light-emitting side parts 33 and 34, so as to be symmetrical with respect to the line. It is set in.

In the waveguide optical switch having the above configuration, depending on the polarity and magnitude of the voltage applied to the electrode 4, the refractive index of the region (refractive index change region) facing the electrode 4 increases (+Δn effect) or decreases ( −Δn effect). Therefore, by applying a signal voltage to the electrode 4, the light incident from the direction of the arrow X can be made to travel straight in the direction of the arrow Y or branched in the direction of the arrow Z.

[Problem that the invention seeks to solve]

In the above-mentioned conventional waveguide optical switch (2), a thin rectangular electrode is placed at the intersection of two leading waveguides, and its long side is
The intersection angle apex P formed by the edges of the light incident side portions of the two leading waveguides
Since the line is narrower than the width of the input/output line and is provided on the line connecting the intersection angle vertices Q formed by the edges of the light output side part,
It is difficult to achieve such a structure in a light guide where the line width is narrow because alignment of the electrodes at the intersection of the waveguides requires precision.

[Means for solving problems]

The present invention provides a waveguide type optical switch that solves the above-mentioned problems, and its means include forming a refractive index changing region that covers the entire intersection group of two leading waveguides; This is solved by providing means for changing the refractive index of the .

[Effect]

In the above-mentioned waveguide type optical switch, since the electrodes are provided over the entire intersection of the two leading waveguides, there is no need for alignment accuracy of the electrodes at the intersection of the waveguides, and the polarity of the voltage applied to the electrodes is not required. By selecting the size and size, the incident light can be emitted straight or branched.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram of main parts for explaining the structure of a crossed waveguide type optical switch using the electro-optic effect according to an embodiment of the present invention.
A waveguide 3 having a higher refractive index than the substrate 1 that intersects two is formed on the surface of a substrate 1 made of an electro-optic crystal such as Oz) in the same manner as in the conventional method. An electrode 5 is provided so that an electric field is applied.

By applying a signal voltage to the electrode 5, light incident from the direction of the arrow X can be made to travel straight in the direction of the arrow Y or branched in the direction of the arrow Z.

If the thermo-optic effect is used, the change in refractive index can be made larger than in the waveguide optical switch that uses the electro-optic effect, so a waveguide optical switch with good performance can be obtained.

2 and 3 are a plan view of a main part and a cross-sectional view of a waveguide intersection part to explain the structure of a cross-wavelength optical switch that utilizes the thermo-optic effect. An oxidized 5iOz film 12 is formed, and a TiXSi+-xO□ waveguide 13 is formed on it so that the two waveguides intersect.
is provided, and a protective layer of a 5in2 film 14 covers it. Further, an electrode 15 of a resistor (for example, Ti) is formed so as to cover the entire intersection. In addition, SiO□
The film 14 has a smaller refractive index than the Ti, Si, -XO□ waveguide 13 and enhances the waveguide effect.
It also serves as optical insulation.

By applying a signal voltage to the electrode 15, the temperature of the intersection under the electrode 15 increases, and as a result, the refractive index change region (
The refractive index of the intersection (crossing part) shows an increase (+Δn effect). Therefore, by applying a signal voltage to the electrode 15, the light incident from the direction of arrow X can be made to travel straight in the direction of arrow Y or branched in the direction of arrow Z. let

In a switch configured in this way, as the refractive index of the intersection portion increases, the state where the light is emitted to the straight side and the state where the light is emitted to the branch side occur alternately. Therefore, by controlling the temperature rise with current, a good switch can be made. Can be configured.

〔Effect of the invention〕

As explained above, according to the present invention, there is no need for alignment accuracy between the intersection portion of the waveguide and the electrode, and therefore a small and integrated waveguide optical switch can be easily manufactured.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the main parts for explaining the structure of a crossed waveguide type optical switch using the electro-optic effect according to an embodiment of the present invention. FIGS. A plan view of the main parts and a cross-sectional view of the waveguide crossing part to explain the structure of the Shika waveguide optical switch, and FIG. 4 is a schematic diagram of the main parts to explain the structure of the waveguide of the conventional crossed waveguide optical switch. FIG. 5 is a schematic diagram of a main part for explaining the structure of a conventional crossed waveguide type optical switch. In the figure, ①, 11 is the substrate, 2 is the titanium thin film layer, 3.1
3 is a leading waveguide, 4, 5.15 is an electrode, 12, 14 is a 5i02 film, 31.32 is a light incident side part, 33,
Reference numeral 34 indicates the light exit side portion, and P and Q indicate the intersection angle vertices of the optical waveguide, respectively. Figure 1/+LI2, 1L Figure 3

Claims (1)

[Claims] A refractive index changing region and a means for controlling the refractive index thereof by either a thermo-optic effect or an electro-optic effect are provided in the entire crossed waveguide formed on the substrate, and the optical path of the incident light is changed. Waveguide type optical switch.