JPS6029714A - Optical semiconductor device - Google Patents

Abstract

PURPOSE:To obtain high coupling efficiency between an optical semiconductor element and an optical fiber by inserting the optical fiber into a guide opposite to the optical semiconductor element, and fixing it to a stem at a position which is <=2mm. away from the tip of the guide. CONSTITUTION:The tip of the optical fiber 6 which is inserted into the fiber guide 9 and fixed projecting by a proper extent is positioned at a proper interval from the optical semiconductor element 5. Then, the guide 9 is deformed plastically for such an adjustment that light from the optical semiconductor element 5 is incident on the fiber 6 to a maximum quantity, and then a fixing material 7 is fixed to the position of the projection part 10 of a pedestal 3. The flexural rigidity of the guide 9 is much larger than that of the fiber 6, so it is not influenced by the setting contraction of the fixing material 7. Therefore, the material is fixed after the optical axis is aligned, so its precision is improved and the assembly yield and reliability are also improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an optical semiconductor device having an optical semiconductor element and an optical fiber, and in particular to optical semiconductor devices and optical fibers that are optically coupled with high efficiency. This invention relates to a structure suitable for fixing.

[Background of the invention]

In recent optical semiconductor devices for communication, optical fibers and optical semiconductor elements (chips) are often optically coupled inside the package to make it airtight.In such packages, the light emitted from the chip is In order to efficiently guide the emitted light to the optical fiber, it is important to align the optical 7 eyer and the chip with high precision and to fix them without positional deviation. In particular, when a single mode fiber is used as the optical fiber, the permissible amount of positional deviation during the above-mentioned alignment and fixing or after fixing is approximately 1 μm or less, making it even more difficult.

Conventionally, as such an optical semiconductor device, one having a structure as shown in FIGS. 1 and 2 has already been proposed. This optical semiconductor device is assembled into a rectangular stem 1. The optical fiber 6 is inserted into the stem 1 by passing through a fiber guide 9 made of a plastic metal fixed to the stem 1, and then fixed to the distal end of the fiber guide 9 by a fixing material 8 such as resin. To align the optical axes of the optical fiber 6 and the optical semiconductor element 5, the seven-eyeper guide 9 is plastically deformed to precisely align the two. Next, the tip of the optical 7-eyeper 6 is fixed to the pedestal part 3 of the stem 1 with a fixing material 7 such as resin.

By the way, in this structure, when fixing the tip of the optical fiber 6, the fixing material 7 such as resin hardens and shrinks, resulting in positional shift, resulting in a decrease in optical coupling efficiency, especially when using a single mode fiber with a core diameter of several μm. In this case, there was a drawback that the light was almost completely cut off.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical semiconductor device which overcomes the above-mentioned drawbacks and which can obtain high optical coupling efficiency between an optical semiconductor element and an optical fiber.

[Summary of the invention]

In order to achieve such an object, the present invention is characterized in that a fiber guide is fixed in place of fixing the optical fiber. That is, since the optical fiber guide has significantly higher bending rigidity than an optical fiber, the influence of curing and shrinkage of the fixing material when the tip is fixed can be significantly reduced.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail with reference to Examples.

FIG. 3 and FIG. 4 show an embodiment of the present invention (Example 1). The optical fiber 6 is inserted into the fiber guide 9 after its tip is tapered, and fixed to the fiber guide 9 with an appropriate amount of protrusion. Note that the tip of the optical fiber 6 is positioned relative to the optical semiconductor element 5 so as to maintain an appropriate distance (for example, 5 to 40 μm and 8 degrees). Next, the fiber guide 9 is plastically deformed and adjusted so that the light from the optical semiconductor element 5 can be taken into the optical fiber 6 in the largest possible manner. Finally, the fiber guide 9 is fixed to the position of the protrusion 10 of the pedestal 3 via the fixing member 7.

In this case, the fiber guide 9 has extremely high bending rigidity compared to the optical fiber 6. In other words, the bending stiffness is EI
[: E: modulus of longitudinal elasticity, ■: moment of inertia of area, for pipes, it is expressed as I = -(do' -4 d+')), and the fiber guide 9 used in this example (outer diameter do ==Q, 5. Inner diameter d, =0.17n
+m) is the optical fiber 6 (outer diameter d o = 0.
125m). Also, E is 1.2 x 10' for fiber guide 9 (cupronickel) and '4f/wi, whereas it is 0.0 for optical fiber 6 (quartz).
It is about 73X10'Kgf/mA. That is,
The bending rigidity per unit length of the fiber guide 9 is approximately 490 times greater than that of the optical fiber 6. As a result of this increase in bending rigidity, it is thought that the effect of hardening and shrinkage of the fixing member 7 when fixing the fiber guide 9 is reduced to about 1/490, and by this fixing method, it is possible to , it turns out that it is easy to maintain.

In the first embodiment, the curing and shrinkage of the fixing member 7 occurs only in one direction, so that although the degree of influence thereof is reduced, some positional deviation will always occur. The following example was devised to solve this problem (Example 2).

That is, as shown in FIGS. 5 and 6, a through hole 11 with an inner diameter of 0.9 mm is formed in the protrusion 10 provided on the pedestal 3, and the fiber guide 9 (outer diameter 0.5 rrrm) is passed through the through hole 11. In this state, the optical axis is aligned and the fiber guide 9 is fixed. In this way, insert the fiber guide 9 into the hole 1.
1, the fixing material 7 will not undergo curing shrinkage in any direction, and the amount of positional deviation that will eventually occur will be much smaller than in the case of the first embodiment. In addition, if a positional shift still occurs, the optical axis can be slightly re-adjusted by bending the middle 1 minute of the fiber guide 6 (the middle part between the protruding part 10 and the stem 1) vertically and horizontally. there were.

In the second embodiment described above, a structure was adopted with the aim of significantly suppressing the amount of positional deviation during fixation. On the other hand, in the following example, a method is shown in which fine adjustment is performed after fixation to obtain the highest coupling rate (Example 3).

In this embodiment, as shown in FIGS. 7 and 8, the protrusion 10 on the pedestal 3 is 1.
■Characterized by retreating. That is, after plastically deforming the fiber guide 9 to align the optical axis and fixing it with the fixing material 7, a slight positional deviation (estimated to be about 0.5 to 1 μm) is removed from the protrusion 10 toward the element side. The protruding fiber guide portion is plastically deformed and fine-tuned again.

This makes it possible to perform optical coupling with extremely high efficiency even when it is necessary to perform submicron optical axis alignment, such as when using a single mode fiber.

Note that on the actual flow side, the amount of retraction of the protruding portion 10 is determined based on the balance between workability and long-term maintainability of the optical axis position. That is, the greater the amount of retraction, the easier it is to make fine adjustments again, but on the other hand, it is conceivable that the plastically deformed portion may slightly recover over time, causing a slight positional shift. Considering this point, the retraction value should be in the range of 0.5 to 2 circles from the tip of the 7-eyeper guide 9 (the upper edge cut diagonally), especially in the range of 1 to 1.
A range of 5 ram was suitable.

On the other hand, the fiber guide 9 of the optical fiber 6 in the present invention
There is also a suitable range for the amount of protrusion. That is, when the amount of protrusion is large, it is possible that the amount of positional deviation due to external vibrations and loads becomes large.

To prevent this, it is preferable to have a small protrusion, but on the other hand, when fixing the optical fiber 6 to the fiber guide 9, a fixing material is applied to the entire circumference, so if the protrusion is too small, There is a risk that the material 8 may be applied to the tip of the optical fiber 6 and block light. In the package to which the present invention is applied, the taper portion at the tip of the optical fiber 6 is 0.1
The amount of protrusion of the optical fiber 6 needed to be slightly larger than this. As a result of the experiment, 0.3
It was possible to assemble within the range of ~2ttm, but 0.
A range of 3 to 1+ mm, particularly around 0.5 mm, was suitable.

The fixing material 7.8 used in the present invention is used both between the fiber and the fiber guide and between the fiber guide and the pedestal protrusion.
Metal solder (pb-8n solder, In, etc.) even with resin
But it is possible. However, if airtight sealing is required between the optical fiber 6 and the fiber guide 9, or if long-term reliability is particularly required, it is preferable to use metal solder. It can be said that by applying the present invention, it is easy to use solder for fixing, and it is easy to improve the reliability of the package.

In addition, in Example 3, the pedestal protruding part was explained in a shape having a through hole similar to that in Example 2, but in Example 1
It can also be applied to a flat surface similar to the above, or a semicircular shape, and can be appropriately designed to improve workability especially when fixing with solder.

[Effects of the Invention] As described above, according to the present invention, after aligning the optical axis of the optical fiber with respect to the optical semiconductor element, it is possible to easily fix the optical fiber while maintaining the accuracy. As a result, even in an optical semiconductor device using a single mode fiber, which has been considered extremely difficult until now, it is possible to obtain the required optical axis alignment accuracy in the submicron range. In addition to improving the optical coupling efficiency as described above, it is also possible to improve the assembly yield and reliability, and it is expected that great effects will be achieved when put to practical use.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a conventional optical semiconductor device with an optical fiber.
Figure 2 is an enlarged sectional view showing a part of Figure 1.
FIG. 4 is a sectional view of an optical semiconductor device with an optical fiber according to Example 1 of the present invention, and FIG. 5 is an enlarged sectional view showing a part of FIG.
6 is an enlarged sectional view showing a part of FIG. 5, and FIG. 7 is a sectional view of an optical semiconductor device with an optical fiber according to Embodiment 2 of the present invention. FIG. 7 is an enlarged sectional view showing a part of FIG. A cross-sectional view of a semiconductor device with an optical fiber; FIG. 8 is an enlarged cross-sectional view showing a part of FIG. 7; DESCRIPTION OF SYMBOLS 1... Stem, 3... Pedestal part, 5... Optical semiconductor element, 6... Optical fiber, 7... Fixing material, 8... Fixing material, 9... World Fig. 2 ￥A 3 (￥) U Fig. 4 χ 5 Mouth knife 611D Fig. 7 Fig. 8 B

Claims (1)

[Claims] An optical semiconductor device having an optical semiconductor element and an optical fiber, characterized in that the optical fiber is inserted into and fixed to a fiber guide made of plastic metal, and the fiber guide is fixed to a stem within 2 m from the tip. Optical semiconductor device.