JPH0728055B2 - Optical semiconductor module - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] In an optical semiconductor module that optically couples an optical fiber serving as an optical transmission line with a light-emitting / light-receiving element, light is emitted from a shaft hole.
A large numerical aperture optical fiber whose tip facing the light receiving element is machined in a desired manner is used to optically couple the optical fiber and the light emitting / receiving element via an intermediate ferrule inserted in the axial hole. An optical semiconductor module having high coupling efficiency and low cost is provided.

[Industrial application field]

The present invention relates to an improvement in an optical semiconductor module that optically couples an optical fiber with a light emitting / receiving element.

In communication equipment, electronic equipment, etc., when an electric signal is converted into an optical signal and an optical fiber is used as a transmission path, there are advantages such as low transmission loss, high speed, and no electrical interference to the signal. .

Such communication equipment and electronic equipment include photoelectric conversion means,
That is, an optical semiconductor module that optically couples the light emitting / receiving element and the optical fiber is required.

Such optical semiconductor modules are required to have high optical coupling efficiency and low cost.

[Conventional technology]

FIG. 3 is a block diagram of an example of a conventional optical semiconductor module, and FIG. 4 is a block diagram of another example of a conventional optical semiconductor module.

In FIG. 3, the light emitting / receiving element 1 is housed in a package 3 made of metal, for example, Kovar, having a coefficient of thermal expansion substantially equal to that of optical components such as a lens and an optical fiber. A lens 2 is attached to the front surface.

The lens 4 for transmitting and receiving parallel light rays to and from the lens 2 is inserted and attached to the axial center portion of a lens holder 5 made of, for example, Kovar having a hollow cylindrical shape. The lens holder 5 has its one end face fixed to the end face of the package 3 by, for example, laser welding, so that its axis coincides with the optical axis of the light emitting / receiving element 1.

A sufficiently long optical fiber 8 serving as an optical transmission line has its end portion inserted into a shaft hole of a cylindrical ferrule 7 made of, for example, Kovar, and is fixed with an adhesive.

After inserting the optical fiber 8 in the axial center as described above, the ferrule end surface 7A is ground flat together with the end surface of the optical fiber 8.

The ferrule end surface 7A is installed at the focal position of the lens 4, and in order to optically couple the tip optical fiber 8 and the light emitting / receiving element 1, the end surface of the lens holder 5 opposite to the package 3 is made of, for example, Kovar. The ferrule holder 6 is fixed by, for example, laser welding.

The ferrule holder 6 has a cylindrical shape with a flange whose inner diameter is slightly larger than the outer diameter of the ferrule 7, and is fixed so that its axis coincides with the optical axis of the lens 4.

The ferrule 7 is inserted into the hollow hole of the ferrule holder 6 as described above, and the position of the ferrule 7 is adjusted so that the end face 7A of the ferrule becomes the focal length of the lens 4.
The outer peripheral portion and the end face portion of the ferrule holder 6 are fixed by, for example, laser welding.

Since the conventional optical semiconductor module is configured as described above, when the light emitting / receiving element 1 is a light emitting element, the emitted light is collimated by the lens 2 and projected on the lens 4 to 4, the optical fiber 8 converges at the end face.

Further, when the light emitting / receiving element 1 is a light receiving element, the light emitted from the optical fiber 8 becomes parallel rays at the lens 4,
The light is projected onto the lens 2 and is converged by the lens 2 on the light receiving surface of the light emitting element.

That is, the light emitting / receiving element 1 and the optical fiber 8 are optically coupled.

Such an optical fiber 8 is an optical fiber that is generally widely used, and therefore has an advantage of low cost.

In the conventional example shown in FIG. 4, a tip tapered optical fiber 9 having a tapered tip is inserted into the axial center hole of the ferrule 7 shown in FIG. That is, ferrule 7
On the end face of the light emitting / hole receiving element 1 side, the tip end of the tip taper optical fiber 9 is projected in a taper shape.

Such a tapered tip optical fiber 9 has an advantage that it has a large numerical aperture and a high optical coupling efficiency with the light emitting / receiving element 1.

[Problems to be solved by the invention]

However, the former of the above-mentioned conventional examples, that is, the optical semiconductor module using the generally used optical fiber 8 having a flat tip end has a small numerical aperture because the end face of the optical fiber 8 is a flat surface, and therefore the light emitting / receiving element 1 is However, there is a problem that the optical coupling efficiency is low.

In the latter case, that is, in the optical semiconductor module using the tip tapered optical fiber 9, since the tip of a long optical fiber is tapered, it is possible to obtain a highly accurate tapered surface due to the difficulty in handling during tapering. There is a problem that the yield is difficult and the cost is high.

[Means for solving problems]

In order to solve the above-mentioned conventional problems, the present invention provides an optical semiconductor module for optically coupling an optical fiber 8 serving as an optical transmission line and a light emitting / receiving element 1 as shown in FIG. After inserting the fiber 8, the ferrule 21 whose flat end face is the ferrule end face 21A and the ferrule end face 2
A large numerical aperture optical fiber with a flat rear end that abuts 1A, and the end facing the light emitting / receiving element 1 is processed as desired.
The configuration is such that 10 is provided with an intermediate ferrule 20 inserted in the axial center, and the light emitting / receiving element 1 and the optical fiber 8 are optically coupled via the intermediate ferrule 20.

The specific structure of the large numerical aperture optical fiber 10 is a tapered optical fiber, or a hemispherical optical fiber 12 as shown in FIG. 2, or an optical fiber having a flat tip.
A spherical lens 11A is fixed to the end surface of 11.

[Action]

According to the above-mentioned means of the present invention, the optical fiber inserted into the axial hole of the intermediate ferrule 20 has a tip end on the side facing the light emitting / receiving element 1, a tip taper, a tip hemispherical surface, or a flat tip end. Since the spherical lens 11A is fixed to the end face of the fiber and is the large numerical aperture optical fiber 10, the optical coupling efficiency between the light emitting / receiving element 1 and the intermediate ferrule 20 is high.
Since the ferrule end surface 21A and the intermediate ferrule end surface 20A are in close contact with each other, the optical fiber 8 and the intermediate ferrule are in contact with each other.
High optical coupling efficiency with 20.

On the other hand, the large numerical aperture optical fiber 10 inserted into the axial center hole of the intermediate ferrule 20 is short, and after insertion into the axial center hole of the intermediate ferrule 20, the desired tip portion can be processed,
Due to the ease of handling, it can be easily processed into a desired shape, the yield is good, and the obtained optical semiconductor module is low in cost.

〔Example〕

The present invention will be specifically described below with reference to the drawings. The present invention will be specifically described below with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention, FIG.
3B is a cross-sectional view of the essential parts of another embodiment of the present invention.

In FIG. 1, the light emitting / receiving element 1 is housed in a package 3, and a lens 2 is mounted on the front surface of the light emitting / receiving element 1.

The lens 4 for transmitting and receiving parallel light rays to and from the lens 2 is inserted in the axial center portion of the lens holder 5, and the lens holder 5 has the axial center aligned with the optical axis of the light emitting / receiving element 1 of the package 3. It is fixed to the end face by, for example, laser welding.

A sufficiently long optical fiber 8 serving as an optical transmission line has its end portion inserted into the axial center hole of the ferrule 21 made of, for example, Kovar and fixed with an adhesive, and its ferrule end surface 21A.
Are polished flat together with the end face of the optical fiber 8.

An intermediate ferrule 20 having an outer diameter equal to the outer diameter of the ferrule 21 and a short length, for example, Kovar, has a large numerical aperture optical fiber 10, in the drawing, a tapered optical fiber end installed in its axial hole. Ferrule end face 21 of intermediate ferrule 20
The end surface 20A of the intermediate ferrule that is in contact with A is ground flat together with the end surface of the large numerical aperture optical fiber 10.

Also, on the end face opposite to the intermediate ferrule end face 20A,
The tapered tip of the large numerical aperture optical fiber 10 projects.

The intermediate ferrule 20 is a sleeve made of, for example, Kovar.
The intermediate ferrule end surface 20A is inserted into one end of each of the hollow holes 22 so that the intermediate ferrule end surface 20A is positioned substantially in the middle, and is fixed by, for example, laser welding.

Further, the ferrule 21 is inserted into the hollow hole of the sleeve 22 from the side opposite to the intermediate ferrule 20, and the ferrule end face 21
With A in contact with the end face 20A of the intermediate ferrule,
Sticked to 22.

On the other hand, the ferrule holder 6 is fixed to the end surface of the lens holder 5 opposite to the package 3 by, for example, laser welding. The inner diameter of the ferrule holder 6 is substantially equal to the outer diameter of the sleeve 22, and the ferrule holder 6 is fixed so that its axis coincides with the optical axis of the lens 4.

The sleeve 22 having the intermediate ferrule 20 and the ferrule 21 inserted therein is inserted into the hollow hole of the ferrule holder 6 as described above,
After adjusting the tip of the large numerical aperture optical fiber 10 to the position where the coupling degree is maximum at the focal position of the lens 4, the sleeve 22 and the ferrule holder 6 are fixed by laser welding, for example.

As described above, since the light emitting / receiving element 1 and the optical fiber 8 are coupled through the intermediate ferrule 20 in which the large numerical aperture optical fiber 10 is inserted, the light emitting / receiving element 1 and the intermediate ferrule 20, the intermediate The ferrule 20 and the ferrule 21 have high optical coupling efficiencies, and therefore the optical semiconductor module has high optical coupling efficiency between the light emitting / receiving element 1 and the optical fiber 8. Further, since the large numerical aperture optical fiber 10 is short and the desired tip portion can be processed after being inserted into the axial center hole of the intermediate ferrule 20, it is easy to handle, the yield is good, and the optical semiconductor module is low in cost. The cost.

The intermediate ferrule 20 shown in FIG. 2 (a) has an optical fiber 11 with a flat tip end inserted into the axial center hole,
Optical fiber with a flat tip that protrudes to the opposite side from 20A 11
The spherical lens 11A is fixed to the end surface of the optical element with an optical adhesive.

In the intermediate ferrule 20 shown in FIG. 2 (b), the optical fiber is inserted into the axial hole, and the tip end surface of the optical fiber protruding from the side opposite to the intermediate ferrule end surface 20A is processed into a hemispherical surface. The optical fiber is a tip hemispherical optical fiber 12.

Further, it goes without saying that the tip end may be processed into a hemispherical surface before being inserted into the intermediate ferrule 20 and then the tip hemispherical optical fiber 12 may be inserted into the axial center hole of the intermediate ferrule 20.

The present invention is not limited to the illustrated embodiment, and may have a fixing structure in which the lens holter 5 and the ferrule holder 6 are screwed. Such screwing means has an advantage that the position adjustment of the tip of the large numerical aperture optical fiber 10 is easy.

〔The invention's effect〕

As described above, the present invention is configured to optically couple the optical fiber and the light emitting / receiving element via the intermediate ferrule in which the large numerical aperture optical fiber is inserted, and the optical coupling efficiency is high, and It has excellent practical effects such as high yield at the time of processing a large numerical aperture optical fiber and low cost.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention, FIGS. 2A and 2B are cross-sectional views of main parts of another embodiment of the present invention, and FIG. 3 is a configuration diagram of a conventional example, FIG. 4 is a block diagram of another conventional example. In the figure, 1 is a light emitting / receiving element, 3 is a package, 5 is a lens holder, 6 is a ferrule holder, 7 is a ferrule, 7 is a ferrule, 7A, 20A and 21A are end faces of a ferrule, 8 is an optical fiber, and 9 is a tapered optical fiber end. , 10 is a large numerical aperture optical fiber, 11 is a distal planar optical fiber, 12 is a distal hemispherical optical fiber, 20 is an intermediate ferrule, and 22 is a sleeve.

Claims (4)

[Claims] 1. An optical semiconductor module for optically coupling an optical fiber (8) serving as an optical transmission line and a light emitting / receiving element (1), wherein an end of the optical fiber (8) is inserted into an axial hole. The ferrule (21) and the rear end face that contacts the ferrule end face (21) are flat end faces,
Further, the tip end facing the light emitting / receiving element (1) is provided with a large numerical aperture optical fiber (10) having a desired processing, and an intermediate ferrule (20) inserted into an axial center hole. 8) and the light emitting / receiving element (1),
An optical semiconductor module, which is optically coupled via the intermediate ferrule (20). 2. The optical semiconductor module according to claim 1, wherein the large numerical aperture optical fiber (10) is a tapered optical fiber end. 3. The spherical lens (11A) is fixed to the end surface of the tip flat optical fiber (11) in the large numerical aperture optical fiber (10). The optical semiconductor module described. 4. The optical semiconductor module according to claim 1, wherein the large numerical aperture optical fiber (10) is a tip hemispherical optical fiber (12).