JPS6234126A - Optical waveguide type device - Google Patents

Abstract

PURPOSE:To connect both waveguides to each other and to suppress light loss small on the whole by forming the 1st optical waveguide where an optical function element is formed at a specific part of a substrate and forming the 2nd waveguide which has small waveguide loss at another part of the same substrate. CONSTITUTION:A buffer layer 2 is formed on the substrate 1 by sputtering and the 1st waveguide 3 where an inter-digital transducer 7 is formed is formed on the substrate 1 at its center part. Further, the 2nd waveguides 4 are formed of a material having small light waveguide loss on buffer layers 3 on both sides on the same substrate 1. Those waveguides 4 are provided with lenses 5 and 6 and both waveguides 4 are coupled mutually on their end surfaces through the waveguide 3. Then, light from a laser diode 8 is collimated by the lens 5 and a surface acoustic wave SAW is generated by the piezoelectric effect of the waveguide 3; and the light is propagated and converted by the lens 6 of the waveguide 4, and the light is made incident on a photodetector array 9.

Description

DETAILED DESCRIPTION OF THE INVENTION Summary of the Invention A first material made of a material having an optical functional effect is placed on a predetermined portion on a substrate.
an optical waveguide is formed on the same substrate, and a second optical waveguide made of a material with small optical waveguide loss is formed on another part of the same substrate,
Both of these optical waveguides are connected to each other, and an optical functional element is created in the first optical waveguide. Optical waveguide device.

BACKGROUND OF THE INVENTION The present invention relates to optical waveguide devices for optical integrated circuits.

An optical integrated circuit confines light in an optical waveguide on a substrate, controls the light using various effects, and processes optical signals. Optical spectrum and spectra as specific optical devices
Analyzer, optical convolver.

Examples include optical Bragg shifters and optical Fourier transformers. These lights are controlled using piezoelectric effects, electro-optic effects, acousto-optic effects, thermo-optic effects, and the like. There are only a limited number of materials that have this effect. Furthermore, materials with such effects do not necessarily have small optical waveguide loss;
There are times when it is not possible to achieve light propagation with low loss. For example, ZnO has a piezoelectric effect and can directly excite surface acoustic waves (SAW), but the propagation loss of ZnO is about 5 dB/cm, and Ti diffusion L I N b
About 0.1 dB/cm of O3 and about 1 dB of glass material
/cm. Therefore, the attenuation of light is large.

It has drawbacks such as the need for optical amplification, the need for a light source with a large amount of light, the inability to achieve a large propagation distance, and a poor S/N ratio.

[Purpose of the Invention] The present invention provides an optical waveguide device that can fully utilize the optical functional effects of materials with large propagation loss, and can keep the optical propagation loss low overall. The purpose is to provide

[Configuration and Effects of the Invention] In the optical waveguide device according to the present invention, a first optical waveguide made of a material having an optical function effect is formed on a predetermined portion of a substrate, and a first optical waveguide made of a material having an optical function effect is formed on a predetermined portion of the substrate, and a first optical waveguide is formed on another portion of the substrate. A second optical waveguide made of a material with low loss is formed, both optical waveguides are connected to each other, and an optical functional element is formed in the first optical waveguide.

Here, the optical functional effect refers to a phenomenon in which the properties of a material, especially the properties for realizing an optical functional element, change when some physical quantity is applied from the outside, such as piezoelectric effect, electro-optical effect, magneto-optical effect, etc. . Furthermore, optical waveguides include not only three-dimensional optical waveguides.

The concept includes a two-dimensional optical waveguide, a so-called optical waveguide layer.

Since the first optical waveguide is formed of an optical material having an optical functional effect, various optical functional elements can be formed therein, so that desired optical control can be realized. Even if the optical propagation loss per unit length of this first optical waveguide is large, by keeping the length of this first optical waveguide short, the propagation loss will not become so large.

Since the second optical waveguide connected to the first optical waveguide is selected to have a small propagation loss, it is possible to suppress the propagation loss as a whole. Furthermore, since it is not necessary to provide an optical functional element on the second optical waveguide, it is possible to use a material that does not have an optical functional effect as the second optical waveguide material. In this way, the disadvantages of materials with optical functional effects but high propagation loss and materials with small optical propagation losses but no optical functional effects are mutually compensated for, resulting in an overall low-loss and optically controllable optical guide. Wave type devices can be realized.

[Description of Embodiments] FIGS. 1 and 2 show an embodiment in which the present invention is applied to an optical spectrum analyzer.

A SiO bach film 2 is formed on a Si substrate 1 by sputtering, and a Zn film is deposited on the central part of the film by sputtering and a lift-off method.
An O film 3 is formed, and Corning 7059 glass optical waveguides 4 are formed on both sides of the ZnO film 3 by sputtering and lift-off methods. The ZnO film 3 is also an optical waveguide. Furthermore, rerating lenses 5 and 6 are formed on the two optical waveguides 4 by loading r S t O2 in a predetermined pattern using sputtering and a lift-off method. The central optical waveguide 3 is provided with an interdigital transducer (IDT) 7 that generates a SAW. A laser diode 8 as a light source and a photodetector array (image sensor) 9 are provided on both end faces of the substrate 1 and are end face coupled to the optical waveguide 4, respectively.

The two optical waveguides 4 and the central optical waveguide 3 are also end-coupled to each other.

Light (indicated by a chain line) that is emitted from the laser diode 8 and enters the optical waveguide 4 is collimated by the lens 5 and propagates to the optical waveguide 3. The IDT 7 connects the optical waveguide 3 so as to generate a SAW that propagates in a direction that satisfies the light collimated by the lens 5 and the conditions of Bragg diffraction.
placed above. This is because the optical waveguide 3 has a piezoelectric effect.

When a high frequency voltage is applied to the IDT 7, SAW occurs. The radio frequency (RF) signal whose spectrum is to be analyzed is I
A SAW having a period corresponding to the RF multiplied signal frequency is applied to the DT 7 and interacts with the light propagating through the optical waveguide 3 . The diffraction angle of light diffracted by the SAW (an example of which is shown by a broken line) is approximately proportional to the RF multiplied signal frequency, and the single diffraction efficiency is approximately proportional to the RF power in the small signal region. Such diffracted light and undiffracted light are collected by the lens 6. An optical detection rectangular array 9 is arranged on the fish collecting surface of the lens 6. Therefore, from the detector array 9,
A spectral signal representing the RF multiplied signal frequency and power is obtained.

In such an optical spectrum analyzer, if the total optical propagation distance is 2 cm, if the optical waveguide is formed only from ZnO, the propagation loss will be about 10 dB. but,
When the ZnO film 3 and the glass waveguide 4 are combined, the light
The distance through which nO propagates (that is, the length of the optical waveguide 3) can be as short as the length of the crossed electrodes of the IDT 7, and the propagation loss of the glass optical waveguide 4 is small, so the total loss in this case is about 2 dB. Become.

When glass is used as the optical waveguide 4.

There is an advantage that lenses 5 and 6 of good quality can be manufactured. For example, the refractive index of the buffer layer 2 is 1.4B.

This is because the refractive index of a glass optical waveguide made of Corning 7059 is 1.53, and the difference therebetween is as much as 0.07.

FIG. 3 shows an embodiment in which the present invention is applied to an optical parallel/serial converter. Components that are the same as those shown in FIG. 1 are given the same reference numerals. Central first optical waveguide 3
Second glass optical waveguides 4 are formed on both sides of the substrate 1, and a portion of the left optical waveguide 4 extends toward the left end of the substrate 1, forming a plurality of three-dimensional optical waveguides 14. These optical waveguides 1
An optical signal is introduced into 4 through an optical fiber 11.

The light incident on the optical waveguide 14 is collimated by the lens 5 in the optical waveguide 4.

Head toward the optical waveguide 3. A pulse-like SAW is generated from the IDT7. First, the first light is Bragg diffracted by this pulsed SAW. Since the SAW is pulsed, other light does not interact with the SAW at this time. The diffracted light is directed from the optical waveguide 3 to the right optical waveguide 4, where it is focused by a lens 6. This focused light is extracted by an optical fiber 12. A plurality of lights propagating through the central optical waveguide 3 are successively diffracted by the SAW. In this way, spatially parallel incident light is converted into temporally serial signals.

In the above embodiment, Si is used as the substrate material, 5102 is used as the buffer layer, and ZnO is used as the first optical waveguide material.
Although Corning 7059 is used as the second optical waveguide, it goes without saying that other materials can be used. The method for manufacturing the optical waveguide and the like can also be selected as appropriate depending on the type of material. Furthermore, the lens is not limited to a grating lens, and the manufacturing method can be determined depending on the type of lens.

In the case of grating lenses, in addition to the loaded type made by the Sio2 sputter removal and lift-off method, ion beam etching is performed using photoresist AZ or negative type electron beam resist as a mask and 02F6 as a gas. It is also possible to form a group (groove) quib.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 show an embodiment of this invention.
FIG. 1 is a perspective view, and FIG. 2 is a sectional view. FIG. 3 is a perspective view showing another embodiment of the invention. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Buffer layer, 3... First optical waveguide, 4... Second optical waveguide, 5.6... Lens, 7... IDT. Patent applicant Tateishi Electric Co., Ltd. Agent Patent attorney Kenji Ushiku (and one other person) Sponsored to write the procedure document May 72, 1986

Claims (2)

[Claims] (1) A first optical waveguide made of a material with an optical functional effect is formed on a predetermined part of the substrate, and a second optical waveguide made of a material with low optical waveguide loss is formed on another part of the same substrate. An optical waveguide device in which both optical waveguides are connected to each other, and an optical functional element is formed in the first optical waveguide. (2) The optical waveguide device according to claim (1), wherein a buffer layer is provided between the substrate and the first and second optical waveguides.