JPH06186451A - Optical waveguide device - Google Patents

Abstract

PURPOSE:To obtain the large attenuation rate of crosstalks by providing means, etc., for removing the radiation mode and scattered light propagating in a substrate near the end faces of optical waveguides. CONSTITUTION:The first optical waveguide 11 and second optical waveguide 12 constituted by diffusion of Ti are provided with bends to form proximity parts in the LnNbO3 substrate 10. Electrodes 13, 14 are provided on the optical waveguides in these proximity parts. Grooves 20 of 100mum depth are formed near the end faces of the substrate 10 of these two optical waveguides 11, 12. The radiation mode which is generated in the bend parts of the two optical waveguides 11, 12 and leaking from the two optical waveguide and the scattered light in the substrate are irregularly reflected by these grooves and are not made incident on optical fibers 15, 16 respectively connected to the two optical waveguides and, therefore, the large attenuation rate of the crosstalks is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical waveguide device having improved characteristics used in optical communication and optical sensors, and more particularly to an optical waveguide device having improved crosstalk attenuation.

[0002]

2. Description of the Related Art Conventionally, as an optical waveguide device of this type,
As shown in FIG. 3, there is an optical directional coupler type optical switch in which a first optical waveguide 11 and a second optical waveguide 12 by Ti diffusion on a LiNbO ₃ substrate are provided with two bent portions and a neighboring portion is formed. .

[0003]

In the above-mentioned conventional optical switch as an optical waveguide device, a large crosstalk attenuation is caused, for example, between the ports 1-2 due to the radiation mode generated in the bending portion and the scattering in the substrate and the optical waveguide. It had the drawback that no quantity was available.

Therefore, the present invention aims to improve the above-mentioned drawbacks of the prior art to obtain a large crosstalk attenuation amount.

[0005]

In the optical waveguide device of the present invention, means for removing the radiation mode and scattered light propagating in the substrate near the end face of the optical waveguide formed on the substrate, and the end face of the optical waveguide device An absorption layer is provided except for the optical waveguide portion.

[0006]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a schematic view showing a first embodiment of the present invention. The first optical waveguide 11 and the second optical waveguide 12 formed by Ti diffusion are provided on the z-cut LiNbO ₃ substrate 10 to form a curved portion and a neighboring portion. Electrodes 13 and 14 are provided on the waveguide in this vicinity. A groove 20 having a depth of 100 μm is formed near the end surface of the LiNbO ₃ substrate of the first and second optical waveguides 11 and 12. The first and second optical waveguides 11 and 12 are generated at the bent portions and
The radiation mode leaked from the second optical waveguides 11 and 12 and the scattered light on the substrate are diffusely reflected by the groove 20 and are transmitted to the optical fibers 15 and 16 connected to the first and second optical waveguides 11 and 12, respectively. Is not incident, and a large amount of crosstalk attenuation can be realized. Although the groove 20 is formed by cutting, it may be formed by chemical etching.

Instead of forming the V groove, an absorption film such as a metal film may be provided on at least one of the front surface and the back surface of the substrate, or a material having a higher refractive index than the substrate may be provided. Further, a material having a higher refractive index than the absorption film and the substrate may be provided at the same time. The absorption layer may be formed by forming a metal film of Ni, Cr or the like by using a photolithography technique after forming the optical waveguides 11 and 12. The high refractive index layer may be formed by depositing Ti and thermally diffusing the same as when forming the optical waveguides 11 and 12.
After forming 1, 12, they may be formed by a proton exchange method. Further, the high refractive index layer may also serve as the absorption layer.

Although the groove 20 is provided on the side of the substrate on which the optical waveguide is formed, it may be formed on the back surface of the substrate or on both sides of the substrate. The same applies to the absorption layer and the high refractive index layer.

FIG. 2 is a schematic view showing a second embodiment of the present invention, in which LiNb of the first and second optical waveguides 11 and 12 is used.
The end surface of the O ₃ substrate is shown. First and second optical waveguides 1
An absorption film 21 is provided on the end surfaces of the cores 1 and 12 except the core end surfaces.

Although the case of using LiNbO ₃ for the substrate has been described above, quartz may be used for the substrate.

[0012]

As described above, in the optical waveguide device of the present invention, by providing the radiation mode propagating in the substrate and means for removing scattered light in the vicinity of the end face of the optical waveguide formed in the substrate, There is an effect that the crosstalk attenuation amount can be obtained.

[Brief description of drawings]

FIG. 1 is a first embodiment of an optical waveguide device of the present invention.

FIG. 2 is a second embodiment of the optical waveguide device of the present invention.

FIG. 3 is an example of an optical switch as a conventional optical waveguide device.

[Explanation of symbols]

10 LiNbO ₃ substrate 11 First optical waveguide 12 Second optical waveguide 13,14 Electrode 15,16 Optical fiber 20 Groove 21 Absorption film

Claims (7)

[Claims] 1. An optical waveguide device, characterized in that a means for eliminating a radiation mode propagating in the substrate and scattered light is provided in the vicinity of an end face of the optical waveguide formed on the substrate. 2. The substrate is lithium niobate (LiNb)
The optical waveguide device according to claim 1, wherein the optical waveguide device is o ₃ ) crystal. 3. The optical waveguide device according to claim 1, wherein the means for removing the radiation mode and scattered light propagating in the substrate is a groove formed in the substrate. 4. The optical waveguide device according to claim 1, wherein the means for removing a radiation mode propagating in the substrate and scattered light is an absorption layer formed on the substrate. 5. The optical waveguide device according to claim 1, wherein the means for removing a radiation mode propagating in the substrate and scattered light is a high refractive index layer formed on the substrate. 6. The optical waveguide device according to claim 5, wherein the high refractive index layer also serves as an absorption layer. 7. An optical waveguide device, characterized in that an absorption layer is provided on an end face of an optical waveguide formed on a substrate except a diameter slightly larger than a core diameter of the optical waveguide.