JPS59160106A - Optical circuit element - Google Patents

Abstract

PURPOSE:To regulate the optical characteristic of an optical waveguide as desired and to obtain an optical circuit element which can prevent the deterioration in the characteristic of the optical circuit system by forming a groove on the side face in the direction perpendicular to a substrate and sticking an absorptive material to the wall of the groove so as to provide a prescribed filter effect. CONSTITUTION:A photoresist 6 is stuck to a substrate 1 and thereafter the photoresist in the region apart at a pescribed distance from the side face of an optical waveguide 2 and extending for a prescribed length along the waveguide 2 is removed. The substrate 1 part in the region is then etched to form a groove 3 having the depth predetermined with respect to the waveguide 2, for example, about the same depth as the depth of the waveguide 2. The element in such a state is subjected to vapor deposition from an arrow direction to stick a metallic layer 4' thereto, and thereafter the respective upper parts are removed from the photoresist 6, thereby constituting an optical circuit element. If the absorptive material is provided on the groove wall on the waveguide 2 side of the groove 3 along the waveguide 2 in the above- mentioned way, the light made incident to the waveguide 2 is removed of an unnecessary mode component in the stage of passing the part of the groove 3. Even if the axial alignment of the incident fiber connected to the incident end 2A of the waveguide 2 is slightly inaccurate, the deterioration in the characteristic of the optical circuit system is hardly generated.

Description

Detailed Description of the Invention <4> Technical Field of the Invention The present invention relates to an optical circuit element, and in particular to an optical circuit in which the optical characteristics of an optical waveguide formed on a substrate can be set to a desired shape. Regarding elements.

Background of (El+) Technology Optical circuit elements forming an optical waveguide usually have a tendency for their characteristics to change depending on the polarization direction of propagation within the optical waveguide. Therefore, it is desirable that the light incident on the optical waveguide be of single polarization. For this purpose, a polarization-maintaining fiber is used as the input fiber, and if this fiber is used, most problems regarding the polarization direction can be solved. However, there still remains a problem with the connection between the polarization maintaining fiber and the above-mentioned optical waveguide.

(c) Conventional technology and problems: As mentioned above, when connecting a polarization maintaining fiber to an optical waveguide formed on a substrate, the anisotropic axis of the fiber and the optical waveguide must be aligned relatively closely. If this is not done, an unnecessary mode of optical component will be excited in the leading waveguide, resulting in a problem of deteriorating the characteristics of the optical circuit system.

(d) Purpose of the Invention The present invention was devised focusing on the technical problems of the prior art as described above, and its purpose is to regulate the optical characteristics of an optical waveguide formed on a substrate into a desired pattern. Another object of the present invention is to provide an optical circuit element that can prevent the characteristics of the optical circuit system from deteriorating.

(E) Structure of the Invention And, this object is to form a groove on a side surface of a part of an optical waveguide formed on a substrate in a direction perpendicular to the substrate, and to form a groove in the groove so as to exhibit a predetermined filtering effect. This is achieved by applying absorbent material to the wall.

(・)Examples of the invention The following describes the actual implementation of the invention with reference to the accompanying drawings.
(Explain the columns.

FIG. 1 shows an embodiment of the invention. (2) is a substrate, which is, for example, a LiNb03 board, and if classified according to its cutting method, it would be classified as a Z board. Reference numeral 2 denotes a guide waveguide formed on a substrate. A groove 3 is formed on the side surface of a part of this optical waveguide in a direction perpendicular to the substrate 1, and an absorbing material, for example, is formed on the groove wall of the groove 3 on the optical waveguide side. The metal 4 is attached to constitute the characteristic part of the present invention.

5 is a modulator.

Then, the above-mentioned absorbent material 4 is attached in the following manner. That is, as shown in (2 to 1) in FIG. 2, after the photoresist 6 is attached to the substrate 1, the photoresist is deposited in an area that is a predetermined distance away from the side surface of the optical waveguide 2 and extends for a predetermined length along the optical waveguide 2. remove. Next, the substrate 1 in the above area
The portion is etched to form a groove 3 of a predetermined depth with respect to the optical waveguide 2, for example, the same depth as the leading waveguide 2.

The element in this state is subjected to vapor deposition (oblique vapor deposition) from the direction of the arrow shown in (2-1) in Fig. 2.
Deposit a metal layer 4' as shown in -1). After that,
The upper parts of the bottom resist 6 are removed and
An optical circuit element of the present invention as shown in -2> is constructed.

In this way, by providing an absorbing material on the groove wall of the groove 3 along the leading waveguide 2 on the leading waveguide 2 side, the light incident on the leading waveguide 2 is eliminated from unnecessary modes when passing through the groove 3. component (TE mode component, i.e. lateral component with respect to the substrate) is removed. Therefore, even if the axis alignment of the input fiber (not shown) connected to the input end 2A of the optical waveguide 2 is somewhat inaccurate, the characteristics of the optical circuit system will hardly deteriorate. Also, such a filter part is the same as the modulator and switch part.
Since it is formed on a base, its characteristics are stable.

In the above embodiment, the absorbing material 4 and the groove 3 are provided on one side of the optical waveguide 2, but these may be provided on both sides of the leading waveguide 2.

(G) Effects of the Invention As described above, the present invention provides the following effects: (1) It is possible to reduce the accuracy of input fiber axis alignment, and (2) obtain stable characteristics.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the present invention, and FIG. 2 is a diagram for explaining the process of the characteristic part of the present invention. In the figure, 1 is a substrate, 2 is a leading waveguide, 3 is a groove, and 4 is an absorbing material. Patent applicant: Fujitsu Limited Agent, Patent attorney: Hiroshi Matsuoka Figure 1 Figure 2

Claims (1)

[Claims] A groove is formed on a side surface of a part of an optical waveguide formed on a substrate in a direction perpendicular to the substrate, and an absorbing substance is attached to the groove wall of the groove so as to exhibit a predetermined filtering effect. An optical circuit element characterized in that: