JPH0364843B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical device in which two optical elements such as optical waveguides maintain optical coupling and are aligned and fixed with high precision.

In recent years, due to dramatic improvements in the performance of optical semiconductor elements, optical waveguides, etc., optical fiber communications, optical information processing, etc. have reached the stage of practical use. However, in these optical fiber communications and optical information processing, the light source,
In order to maintain optical coupling, transmission lines, light receiving elements, optical circuits, etc. must be aligned and fixed with an accuracy of usually several μm to several hundred μm, and must be held with high reliability.

Conventionally, bonding and soldering have been used as this fixing means. However, there are problems with adhesion, such as the adhesive's fixing strength is not strong enough and lacks long-term reliability, and it takes a long time to bond, resulting in poor workability. In addition, in soldering, although there are few problems with fixing strength and workability, the heat during solder heating may have an adverse effect on the reliability of optical semiconductor elements, and the heat during solder heating may also cause thermal expansion of components. There were also problems such as shrinkage of the solder during solidification, which deteriorated optical bonding.

An object of the present invention is to solve these problems and provide an optical coupling device that does not reduce reliability or optical coupling due to heating when using bonding materials such as solder that require heating. It is in.

The optical coupling device of the present invention includes a first base that holds a first optical element, and a second base that holds a second optical element that is optically coupled to the first optical element. The first base is provided with a plurality of protrusions, and the second base is provided with holes that fit with the protrusions at positions corresponding to the protrusions.

In the present invention, when a first base having a first optical element and a second base having a second optical element are fixed using a bonding material, a fixing point is provided on the first base. This is limited to only between the protrusion and the hole provided in the second base.

This will reduce the spread of heat when heating the bonding material, which may adversely affect the first and second optical elements thermally, or cause thermal expansion of the base, which may damage the optical coupling between the optical elements. It will no longer deteriorate.

In addition, the bonding material fills the space between the protrusion and the hole into which the protrusion loosely fits, but the stress generated when the bonding material solidifies and contracts is almost isotropic around the central axis of the protrusion. , so that they cancel each other out and almost no positional deviation occurs between the protrusions and the annular portions. Therefore, optical coupling between optical elements is not reduced. In addition, since each hole is arranged at equal intervals or almost symmetrically in the circumferential direction around the optical axis of the optical element, positional deviation due to thermal expansion is canceled out in the direction perpendicular to the optical axis. , the decrease in optical coupling can be further reduced.

Next, the present invention will be explained in detail using the drawings.

Fig. 1 is a perspective view for explaining a conventional example, Fig. 2 is a perspective view for explaining a conventional example;
The figure is also a sectional view. This conventional example is an example of an optical coupling device that couples output light from a light emitting diode 1 to an optical fiber 2.

A light emitting diode 1 as a first optical element is fixed to a stem 3 as a first base. A side plate 8 is fixed to the stem 3. On the other hand, the optical fiber 2, which is a second optical element, is fixed to a terminal fitting 9, which is a second base. The terminal fitting 9 and the stem 3 are held by a fine movement mechanism (not shown), and their positions are adjusted so that the output light of the light emitting diode 1 is efficiently coupled to the optical fiber 2. In this position-adjusted state, solder material 14 is poured into the entire gap between the side plate 8 and the terminal fitting 9 via a soldering iron, whereby the terminal fitting 9 is soldered onto the stem 3.

In such a conventional example, the terminal fitting 9 and the side plate 8
In order to achieve good soldering between the terminal fittings 9 and the side plates 8, the entire surface of the soldering area of the terminal fitting 9 and the side plate 8 must be heated to near the melting point of the solder material 14.

In this case, the heat spread to the stem 3, light emitting diode 1, and optical fiber 2, raising the temperature of these components by more than 100°C. For this reason, there were drawbacks such as a decrease in the reliability of the light emitting diode 1 and a decrease in coupling efficiency of 20% or more due to positional displacement due to thermal expansion or the like.

Next, embodiments of the present invention will be described in detail.

FIG. 3 is a perspective view for explaining the first embodiment of the present invention, and FIG. 4 is a sectional view. This first embodiment is an example of an optical coupling device 15 that optically couples a light emitting diode 1, which is a first optical element, and an optical fiber 2, which is a second optical element.

The light emitting diode 1 is attached to a stem 3 which is a first base.
Fixed. A side plate 8 having protrusions 4 at three locations at equal intervals in a circumferential direction centered on the optical axis of the output light of the light emitting diode 1 is fixed to the stem 3 . On the other hand, the optical fiber 2 is fixed to a terminal fitting 9 which is a second base, and the terminal fitting 9 has holes 10 into which the projections 4 can be loosely fitted.
There are three locations.

The terminal fitting 9 and the stem 3 are held by a fine movement mechanism (not shown) so that the output light of the light emitting diode 1 is efficiently coupled to the optical fiber 2, and the protrusion 4 is loosely fitted into the hole 10. The position will be adjusted as follows. In this position-adjusted state, solder material 14 is poured into each gap between the protrusion 4 and the hole 10 using a soldering iron, thereby optically coupling the light emitting diode 1 and the optical fiber 2 with high efficiency. The terminal fitting 9 is fixed onto the stem 3 while maintaining the position.

In the optical coupling device 15 thus obtained, the solder material 14 is used at the protrusion 4 and the hole 1.
Since it is limited to only the fitting part of 0, solder material 1
4, the soldering work can be completed while the conduction of heat to the stem 3 and the terminal fitting 9 is small. Therefore, the optical elements such as the light emitting diode 1 and the optical fiber 2 may be adversely affected by heating, such as a decrease in reliability, and the stem 3, the terminal fitting 9, etc. may thermally expand, causing damage between the light emitting diode 1 and the optical fiber 2. The coupling efficiency is less likely to decrease. Further, the solder material 14 fills the space between the protrusion 4 and the hole 10, but the stress generated when the solder material 14 solidifies and contracts is generated almost isotropically around the central axis of the protrusion 4. So,
They cancel each other out, so almost no positional deviation occurs.
Furthermore, the holes 10 and the like are arranged at equal intervals in the circumferential direction around the optical axis of the output light of the light emitting diode, thereby further reducing positional deviation. Therefore, the coupling efficiency between the light emitting diode 1 and the optical fiber 2 is not reduced. In fact, in the first embodiment, the temperature rise when soldering the solder material 14 was about 15° C. for the light emitting diode 1 and about 50° C. for the optical fiber 2. Further, the combined reduction in coupling efficiency between the light emitting diode 1 and the optical fiber 2 could be suppressed to 5% or less, a value that does not pose a practical problem. In the conventional method, the temperature of both the light emitting diode and the optical fiber increases by more than 100℃, and the coupling efficiency decreases by 20%.
This was a huge improvement compared to what happened above.

FIG. 5 is a perspective view for explaining a second embodiment of the present invention. The third embodiment includes a waveguide type optical switch 25 and input and output side optical fibers 26, 27,
This is an example of the optical coupling device 15 that couples the optical fibers 28 to 28.

The optical switch 25 is a LiNbO ₃ plate 3 which is an optical crystal.
This is a generally well-known method in which the first and second optical waveguides 31 and 32 are created by thermal diffusion of Ti on the electrode plate 33. By changing the voltage applied to the electrode plate 33, the first optical waveguide This is an optical switch that can be switched to either of two states: coupling the propagating light of 31 to the second waveguide 32, or allowing the light to propagate through the first optical waveguide 31 as is.
In this embodiment, the propagating light of the input side optical fiber 26 is first coupled to the first optical waveguide 31 of the optical switch 25, and then the propagating light is switched and output from the second optical waveguide 32 or the first optical waveguide 31. The light is coupled to first and second output side optical fibers 27 and 28, respectively.

The optical switch 25 is fixed to the stem 3, which is a first base. The stem 3 is provided with four first protrusions 5 and four second protrusions 6. On the other hand, the input side optical fiber 26 is fixed to a first holding plate 38 which is a second base, and the first and second output side optical fibers 27 and 28 are fixed to a second holding plate 39. Note that the distance between the first and second output side optical fibers 27 and 28 is the same as that between the first and second optical waveguides 31 and 28.
The spacing is set in advance to be the same as the spacing of 32.
The first and second holding plates 38 and 39 have four first holes 11 into which the first protrusions 4 and second protrusions 6 can fit loosely, respectively, and four second holes 12. There are several locations. The shape of these holes is designed to facilitate pouring and curing of the bonding material.
This embodiment is slightly different from the first and second embodiments.

Input to the first and second optical waveguides 31 and 32,
The alignment of the output side optical fibers 27 and 28 and the alignment of the first and second projections 5 and 6 and the first and second holes 11 and 12 are the same as in the first and second embodiments. The same is true. In the third embodiment, a thermosetting adhesive epoxy resin 44 is used as a bonding material, and the first and second projections 5 and 6 are connected to the first and second protrusions, respectively.
The bonding material 44 was poured into the gap between the holes 11 and 12, and the output light of an infrared lamp (not shown) was focused into a small beam and applied to the bonding material 44, and the bonding material 44 was cured in a few minutes.

In the second example as well, it was possible to obtain an optical coupling device with less positional deviation, less temperature rise, etc., as in the first example. In the second embodiment, epoxy resin 44 was used as the bonding material, but since this resin can be heated to a high temperature, it is possible to obtain high fixing strength in a short working time, and overcome the drawbacks of conventional adhesives. I was able to make up for it.

Regarding the present invention, many modifications are possible in addition to the above-described embodiments. The first optical element is the light emitting diode 1 and the optical switch 25, and the second optical element is the optical fiber 2. In addition to these, there are also light receiving elements such as photodiodes, semiconductor lasers, etc. , light emitting elements such as gas lasers, passive elements such as ball lenses, squared index focusing rod lenses, planar waveguides, active elements such as ultrasonic light modulation elements, and various other optical elements are used as the first and second optical elements. It can be used as an element.

In addition to the shapes of the projections 4, 5, 6 and holes 10, 11, 12 described in the above embodiments, steps and grooves may be provided on the surfaces of the projections and on the inside of the holes to facilitate adhesion with the solder material 14, etc. It is also possible to make it stronger. In addition to the solder material 14 and the epoxy resin 44, various brazing materials, adhesives, etc. can be used as the bonding material.
In addition, we have shown examples of heating methods such as soldering iron heating and infrared heating, but there are also other heating methods such as burner, high frequency,
Various methods can be applied, such as heating with laser light or the like.

In the embodiment, the first base serves as the stem and the second base serves as the terminal fitting or holder, but it goes without saying that this may be reversed.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a conventional example, FIG. 2 is a sectional view, FIG. 3 is a perspective view showing a first embodiment of the present invention, FIG. 4 is a sectional view, and FIG. It is a perspective view showing an example of this. Here, 1 is a light emitting diode, 20 is a semiconductor laser, and 25 is an optical switch, each of which corresponds to a first optical element. 3 is a stem that corresponds to the base. 2, 26, 27, and 28 are optical fibers, and 22 is a ball lens, each of which corresponds to a second optical element. 9 is a terminal fitting, 24 is a spherical lens holder, and 38 and 39 are holding plates, each of which corresponds to the second base. 4, 5, 6 are protrusions, 10, 11,
12 is the bottom part. Further, 14 is a solder material, and 44 is an epoxy resin, which corresponds to a bonding material.

Claims (1)

[Claims] 1 Consisting of a first base holding a first optical element and a second base holding a second optical element optically coupled to the first optical element, the first base
A plurality of protrusions are provided on the base at equal intervals or at approximately symmetrical positions in a circumferential direction centered on the optical axis of the first optical element, and the protrusions correspond to the protrusions on the second base. A hole that fits into the protrusion is provided at a position, and the first and second optical elements are injected between at least the hole and the protrusion while being optically coupled. An optical coupling device characterized in that the first and second bases are fixed to each other by a bonding material that requires heating.