JP2739812B2 - Condenser lens fixing structure of optical semiconductor module - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical semiconductor module, and more particularly to a fixing structure for a condenser lens.

[0002]

2. Description of the Related Art An optical semiconductor module is a device in which an optical semiconductor device such as a semiconductor laser diode or a semiconductor external modulation device is optically coupled to an optical fiber. In general, a condenser lens is used for coupling an optical semiconductor element and an optical fiber. The condenser lens is housed in a holder having a hollow portion having an inner diameter slightly larger than the outer diameter of the condenser lens, and is fixed with an adhesive or the like. A metal such as Kovar or stainless steel is usually used for the holder. Nickel plating is used for Kovar, and unplated for stainless steel.

In order to increase the coupling efficiency between the optical semiconductor element and the optical fiber, there is a structure for adjusting the position when fixing the condenser lens. As such a structure, for example, Japanese Patent Application No. Sho 62
There is a structure described in JP-A-204251. This is shown in FIG.
As shown in the figure, in the structure that adjusts the position of the condenser lens at the time of a click on a plane, the position can be freely adjusted without a certain clearance (gap) between the condenser lens and the inner diameter of the hollow part. become unable. However, on the other hand, if the clearance gap between the two is too large, after the condenser lens is fixed, the condenser lens is likely to be displaced in the hollow portion due to a change in ambient temperature or a change with time. Needless to say, the optical coupling between the optical semiconductor element and the optical fiber is reduced when there is such a displacement. Therefore, the clearance is usually set to about 1 to 5 μm.

[0004]

However, if the clearance is small, there is a problem that the position of the condenser lens cannot be freely adjusted within the hollow portion of the holder. Further, in the structure shown in FIG. 3, the clearance is small, so that when the condenser lens is moved in the optical axis direction, the inner wall of the hollow portion of the holder is damaged and adjustment becomes impossible. There is a problem that the position of the optical lens 13 cannot be adjusted in a direction perpendicular to the optical semiconductor element 11 and the optical fiber 16.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fixing structure for a condenser lens which can adjust the position of the condenser lens well even if the clearance between the condenser lens and the holder is small, in view of the above-mentioned disadvantages. .

[0006]

SUMMARY OF THE INVENTION In order to eliminate the above-mentioned drawbacks, a converging lens fixing structure for an optical semiconductor module according to the present invention comprises an optical semiconductor element, an optical fiber, and an optical fiber. And a condensing lens fixed to the optical semiconductor module, the condensing lens being housed in a rotating tube having an inner diameter slightly larger than the outer diameter of the condensing lens. The fixed structure further has a holder for accommodating the rotating tube having a hollow portion having an inner diameter slightly larger than the outer diameter of the rotating tube, and at least one of a side surface of the rotating tube and an inner wall surface of the hollow portion of the holder. It is characterized by having been subjected to gold plating.

[0007]

[0008] The present invention is characterized in that the plating applied to the outer wall surface of the holder hollow portion or the side surface of the rotary tube is silver plating instead of gold plating.

[0009]

According to the present invention, the rotating circular tube is rotated inside the holder by plating a relatively soft metal having high malleability such as gold on the outer wall surface of the hollow portion of the holder or the side surface of the rotating circular tube. Or position adjustment in the optical axis direction. At the same time, the contact surface is hardly damaged. In addition, by making the hollow portion of the rotating circular tube eccentric with respect to the outer diameter, positioning in the direction perpendicular to the optical axis is also possible. Also in this case, the contact surface is not easily damaged and can be smoothly rotated, so that fine rotation adjustment is possible.

[0010]

An embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing one embodiment of a condenser lens fixing structure of the optical semiconductor module of the present invention, and FIG. 2 is an enlarged view of the condenser lens fixing structure. Note that, here, the illustration of the optical fiber fixing portion, not the entire module, is omitted and only the vicinity of the condenser lens portion is illustrated.

As an optical semiconductor element, a semiconductor external modulation element 1
Are mounted on the chip carrier 2 via a heat sink (not shown). The semiconductor external modulation element 1 has a function of modulating continuous light incident from one end face by a signal of a current injected from the outside and outputting the modulated light from the other end face. The emitted light is optically coupled to the optical fiber by the condenser lens 3. The condenser lens 3 is accommodated in a rotating circular tube 4 in which the central axis of the inner diameter is eccentric with respect to the outer diameter.
The rotating tube 4 containing the condenser lens 3 is accommodated and fixed in a holder 5 having a circular hollow portion 6 slightly larger than its outer diameter. At the time of fixing, the position of the condenser lens 3 is adjusted in the optical axis direction in the hollow portion 6 of the holder 5 in order to optimize the image magnification between the semiconductor external modulation device 1 and the optical fiber (not shown). At the same time, the rotating circular tube 4 is rotated and adjusted in the holder 5 in order to focus the light emitted from the semiconductor external modulation element 1 near the core of the optical fiber.

In the above fixing structure of the condenser lens, the material of the holder 5 is Kovar, and only the inner wall of the hollow portion 6 is plated with nickel using nickel as a base. Here, the thickness of the nickel plating is about 0.5 μm, and the thickness of the gold plating 7 is about 10 μm. Further, the inside diameter of the hollow portion 6 of the holder 5 after plating and the outer diameter and clearance of the rotating circular tube 4 are about 3 μm. With the conventional structure without gold plating, the rotating circular tube 4 could not be smoothly adjusted in the holder 5, but the gold plating makes it possible to adjust the position well without damaging the wall surface.

In the above-described embodiment of the present invention, the condenser lens 3 is temporarily housed in the eccentric rotating tube 4 so that the direction of rotation can be adjusted. It may be. In the present embodiment, the holder 5
Although the inner wall is gold-plated, it may be provided on the side surface of the condenser lens 3 or the rotating circular tube 4 or on both of the holder. In this embodiment, gold is selected as the plating agent, but silver plating may be used as long as it has high malleability.

[0015]

As described above, the converging lens fixing structure of the optical semiconductor module according to the present invention has a high malleability such as gold on the inner wall surface of the holder or the side surface of the rotating tube accommodating the converging lens. By plating, the position of the condenser lens can be adjusted smoothly and the contact surface is not damaged, so that the position of the condenser lens can be adjusted with high precision.

[Brief description of the drawings]

FIG. 1 is a perspective view of one embodiment of a fixing structure of a condenser lens of an optical semiconductor module of the present invention.

FIG. 2 is an enlarged view of a fixing structure of the condenser lens of FIG. 1;

FIG. 3 is a sectional view of a fixing structure of a condensing lens of a conventional optical semiconductor module.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor external modulation element 2 Chip carrier 3 Condensing lens 4 Rotating circular tube 5 Holder 6 Hollow part 7 Gold plating 11 Optical semiconductor element 12 Chip carrier 13 Condensing lens 14 Rotating circular tube 15 Pointing member 16 Optical fiber 17 Housing

Claims (3)

(57) [Claims] And 1. A optical semiconductor element, and an optical fiber, in the light converging lens fixing structure of an optical semiconductor module that includes a coupled to condenser lens to the optical fiber output light of the optical semiconductor element, the condenser lens Is slightly larger than the outer diameter of the condenser lens.
The optical semiconductor module is accommodated in a rotating circular tube having a large inner diameter, and the condenser lens fixing structure of the optical semiconductor module further includes
A hollow part having an inner diameter slightly larger than the outer diameter of the rotating circular pipe
Having a holder for accommodating the rotating tube, and a side surface of the rotating tube or an inner wall surface of a hollow portion of the holder.
Condenser lens fixing structure of an optical semiconductor module, characterized that you is plated with gold at least one of. 2. The hollow portion has an outer diameter with respect to an outer diameter of the holder.
2. The converging lens fixing structure for an optical semiconductor module according to claim 1, wherein the converging lens is decentered . 3. The side surface of the rotating circular tube or the holder.
2. The condenser lens fixing structure for an optical semiconductor module according to claim 1, wherein the plating applied to at least one of the inner wall surfaces of the hollow portion is silver plating instead of gold plating.