JPS63142310A - Optical connecting method - Google Patents

Abstract

PURPOSE:To eliminate the need for position adjustment by providing grooves while have center axes aligned with optical waveguides on a substrate where the optical waveguides are formed, and installing optical fibers therein. CONSTITUTION:A 1st groove 5 which has its center axis at right angles to the light transmission direction of the optical waveguides 2 and 3 formed on the substrate 1 and a 2nd groove 8 which has its center axis in the light transmission direction of the optical waveguides 2 and 3 and has its one end in the 1st groove 5 are provided in the surface of the substrate 1. Then, the optical fibers 10 and 11 are installed in the 2nd grooves 8 and 9, and the optical fibers 10 and 11 and optical waveguides 2 and 3 are coupled optically with each other. Consequently, an optical connecting method for the optical waveguides 2 and 3 and optical fibers 10 and 11 which facilitates the adjustment and is small in loss increase at the time of fixation is obtained.

Description

[Detailed Description of the Invention] = Industrial Application Field] The present invention relates to an optical connection method for optical devices used in optical communication, optical information processing, etc., and in particular to a method for confining light in an optical waveguide provided on a substrate. The present invention relates to a method of connecting a waveguide optical device for control and an optical fiber.

[Conventional technology]

With the development of optical communication technology, increasingly advanced performance.

The realization of functional optical devices is desired.

For example, high-speed, wide-band optical switches are required to realize switching functions in optical transmission networks, high-speed switching functions between terminals in optical data buses, etc., and to multiplex optical signals and distribute them to terminals. requires devices such as multi-channel duplexers and star couplers.

The optical devices currently in use with the above functions are mainly bulk-type devices using conventional prisms, lenses, etc., and are insufficient in terms of performance such as switching speed and multiplicity. There are problems such as large size and unsuitability for integration.

As a means to solve these problems, progress is being made in the development of waveguide-type optical devices that control light using optical waveguides installed on a substrate. Since the deer waveform optical device confines light in a minute waveguide, it is a small device suitable for integration, and it can also be used to realize extremely highly efficient optical control devices such as optical switches and optical modulators.

When applying a waveguide optical device to an optical communication system, it is necessary to connect optical fibers to the input and output sections. Conventionally, the method for this connection was to adjust the optical fibers individually and fix them to the end face of the optical waveguide. It is taken.

[Problem that the invention seeks to solve]

According to the conventional optical connection method, when connecting an optical waveguide and an end face of an optical fiber, the spread of the optical field distribution for both the optical fiber and the optical waveguide is usually about 10 μm or less, so it is possible to connect the end face of an optical waveguide and an optical fiber with very high precision. It requires adjustment and requires a large amount of adjustment man-hours.

In addition, when fixing both optical fiber and optical waveguide,
Adhesives and metal fusion are used, but they have the disadvantage that they tend to shift in position before they are completely fixed, resulting in an increase in bonding loss. In particular, when connecting multi-channel optical waveguides and optical fiber arrays, the number of adjustment steps and the increase in loss during fixation become large, making it impossible to obtain optical devices with inexpensive and high-performance optical fiber input/output terminals. There was a problem.

An object of the present invention is to provide an optical connection method for optical waveguides and optical fibers that eliminates the drawbacks of the conventional optical connection methods described above, is easy to adjust, and has a small increase in loss when fixed.

[Means for solving problems]

A first aspect of the present invention includes a first groove having a central axis in a direction perpendicular to the light transmission direction of the optical waveguide installed on a substrate, and a central axis coinciding with the light transmission direction of the optical waveguide; a second groove having one end in the first groove is provided on the substrate surface;
It is characterized in that an optical fiber is installed in the groove, and the optical fiber and the optical waveguide are optically coupled.

A second aspect of the present invention has a first groove having a central axis in a direction perpendicular to the light transmission direction of the optical waveguide installed on a substrate, and a first groove having a central axis coincident with the light transmission direction of the optical waveguide, and A second groove having one end in the first groove is formed on the surface of the substrate by mechanical cutting means, an optical fiber is installed in the second groove, and the optical fiber and the optical waveguide are optically connected. This optical connection method is characterized in that a plate is adhered to the surface of the substrate on which the first groove is formed, and the first groove is formed thereon.

A third aspect of the present invention provides a first groove having a central axis in a direction perpendicular to the light transmission direction of the optical waveguide installed on the substrate, and a central axis coinciding with the light transmission direction of the optical waveguide; A second groove having one end in the first groove is formed on the surface of the substrate by mechanical cutting means, an optical fiber is installed in the second groove, and the optical fiber and the optical waveguide are optically connected. The optical connection method is characterized in that the surface of the substrate on which the first and second grooves are formed is coated with a thin film-like substance before forming the grooves.

[Effect]

In the present invention, a groove whose center axis coincides with that of the optical waveguide is provided on the substrate on which the optical waveguide is installed, and the optical fiber is installed in the groove, thereby eliminating the need for position adjustment. However, the groove normally requires a depth approximately equal to the radius of the optical fiber, and the surface on which the end face of the optical waveguide is exposed is required to be vertical, so it is difficult to realize it as is. For example, when a groove is processed using dry etching such as ion beam etching or reactive plasma etching, verticality of the end face of the optical waveguide can be obtained, but it is difficult to form a deep groove. On the other hand, when forming grooves by mechanical cutting using a cutting tool, etc., it is easier to process than dry etching, and deep grooves can be easily obtained, but the perpendicularity of the optical waveguide end face is not achieved. I can't.

Therefore, in the present invention, another groove is provided by mechanical cutting perpendicular to the above-mentioned groove, and the end face of the optical waveguide is exposed on the side wall of the groove, thereby obtaining a vertical end face of the optical waveguide. By providing orthogonal grooves in this manner, it is possible to obtain a groove that satisfies the above conditions, that is, a groove whose depth is approximately the radius of the optical fiber and whose optical waveguide end is perpendicular. By embedding the optical fiber in this groove and fixing it by applying pressure from above, the displacement of the optical fiber during fixing can be significantly reduced compared to the conventional method.

Further, according to the present invention, by forming a plate or a thin film on the substrate surface before forming the groove, it is possible to prevent a crank from entering the groove edge portion due to mechanical cutting.

(Example〕 The present invention will be described in detail below with reference to the drawings.

FIGS. 1(a) and 1(b'l) are diagrams showing an embodiment of the optical connection method according to the first invention, in which (a) is a perspective view when an optical fiber is installed in a groove, and (b) FIG. 2 is a cross-sectional view showing a groove processing method.

In FIG. 1(a), an optical directional coupler 4 is formed by optical waveguides 2 and 3 formed on a lithium niobate substrate 1 by diffusing Ti.

Here, the width of the optical waveguides 2 and 3 is several to ten μm, and the depth is several μm.
It is m. First, the first groove 5 is formed by mechanical cutting in a direction perpendicular to the light transmission direction of the optical waveguides 2 and 3. As a result, the end faces 6 and 7 of the optical waveguide 2.3 are provided on the side wall of the groove 5.
is exposed and can be easily obtained by moving these end faces in a direction perpendicular to the optical waveguides 2 and 3 so as to match the faces of the end faces 6 and 7. Further, in this embodiment, grooves 8 and 9 having central axes that coincide with the light transmission direction of the optical waveguide 2.3 are formed by mechanical cutting at positions opposite to the end surfaces 6 and 7 of the groove 5. The depth of grooves 8 and 9 are both 60 μm
Both widths are approximately equal to the diameter of the optical fiber to be embedded.

Next, in each of these grooves 8 and 9, a diameter of 125μ is inserted.
Optical fibers 10 and 11 having a diameter of about 10 μm and a core diameter of about 10 μm are embedded. In this case, the optical fiber 10.11 is inserted into the groove 8.
The center axis of the optical fiber 10.11 is set to coincide with the center axis of the optical waveguide 2.3 when pressed against the bottom of the optical fiber 10.11. Further, the optical fibers 10.degree. 11 are installed as close as possible to the end surfaces 6, 7 of the optical waveguides so that the distance between them is less than a few micrometers or less. Also,
The optical fiber 10.11 can be fixed with an adhesive or the like by temporarily applying pressure from above the optical fiber 10.11.

In this case, the width of the groove 8.9 is almost the same as the diameter of the optical fiber 10.11, and the groove machining accuracy can easily be ±1 μm or less using the guiding tool, so the positional deviation due to sticking is small. The increase in optical coupling loss is also small.

In the above embodiment, the depth of the groove 5 is uniform, but it does not have to be uniform and may be deeper only in the vicinity of the end faces 6 and 7.

Furthermore, in the above embodiments, the grooves 5, 8, and 9 were all formed by mechanical cutting.
, 7 to the depth of the lower part of the waveguide, that is, to a depth of several μm, by other etching means, such as dry etching or wet etching using laser heating, to make the end surfaces 6 and 7 more flat. can be converted into

FIG. 2 is a sectional view showing an embodiment of the second invention. According to this embodiment, a protective plate 23 is provided on the surface of the portion of the optical waveguide 21 provided on the lithium niobate substrate 1 in contact with the first groove 22 that will be formed, for example, with the same niobate as the substrate. Made of lithium, glass, etc., with a thickness of several hundred μm to 1
mm plates are glued together and a first groove 22 is formed thereon using a guising tool.

Normally, when grooves are formed on the surface of a substrate by mechanical cutting means such as a cutting tool, cracks may occur at the edges of the grooves. In this embodiment, by bonding the protective plate 23 onto the optical waveguide 21, it is possible to prevent cracks from forming on the end face of the optical waveguide 21 when forming the groove 22.

Incidentally, the embedding of the optical fiber 24 is performed in the same manner as in the embodiment shown in FIG.

FIG. 3 is a sectional view showing an embodiment of the third invention. In this embodiment, like the embodiment shown in FIG. 2, a thin film 25 is coated on the optical waveguide 21 in order to prevent cranks from occurring on the end face of the optical waveguide during groove formation. Materials for the thin film 25 include metal films such as Cr, Au+Ti, A/, etc.
An insulating film such as iO□, Si3N4, or a composite multilayer film thereof can be used, and the thickness is several hundred to nanometers.

In this embodiment, before forming the first and second grooves, only the portions of the thin film 25 where these grooves are to be formed are removed by a method such as etching, and the grooves are formed based on the thin film pattern, thereby determining the position of the grooves. It can be easily matched.

Although a lithium niobate substrate was used as the substrate in each of the above embodiments, the present invention can be applied to any material such as a glass substrate or a semiconductor substrate as the substrate material.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to obtain an optical connection method between an optical waveguide and an optical fiber, which is easier to adjust than the conventional method and has a small increase in loss during fixation.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the optical connection method according to the first invention, in which FIG. 1(a) is a perspective view, FIG. 1(b) is a sectional view, and FIG. FIG. 3 is a sectional view showing an embodiment of the optical connection method according to the present invention. FIG. 3 is a sectional view showing an embodiment of the optical connection method according to the third invention. 1... Lithium niobate substrate 2.3.21.
... Optical waveguide 5.22 ... First groove 8.9 ... Second groove for inserting optical fiber 10.11.24 ... Optical fiber agent Patent attorney Yoshiyuki Iwasa (a) no j (b) Figure 1

Claims (5)

[Claims] (1) A first groove having a central axis in a direction perpendicular to the light transmission direction of the optical waveguide installed on the substrate; An optical connection method characterized in that a second groove having one end is provided on the surface of the substrate, an optical fiber is installed in the second groove, and the optical fiber and the optical waveguide are optically coupled. . (2) The optical connection method according to claim 1, wherein the first and second grooves are formed by mechanical cutting means. (3) The first groove is formed by both mechanical cutting means and other etching means, and the second groove is formed by mechanical cutting means.
Optical connection method described in section. (4) a first groove having a central axis in a direction perpendicular to the light transmission direction of the optical waveguide installed on the substrate; A second groove having one end is formed on the surface of the substrate by mechanical cutting means, an optical fiber is installed in the second groove, and the optical fiber is optically coupled to the optical waveguide. 1. An optical connection method, comprising: adhering a plate to the surface of the substrate on which the first groove is to be formed, and forming the first groove thereon. (5) a first groove having a central axis in a direction perpendicular to the light transmission direction of the optical waveguide installed on the substrate; an optical connection in which a second groove having one end is formed on the surface of the substrate by mechanical cutting means, an optical fiber is installed in the second groove, and the optical fiber and the optical waveguide are optically coupled; 1. An optical connection method, characterized in that the surface of the substrate on which the first and second grooves are formed is coated with a thin film-like substance before forming the grooves.