JP2555945B2 - Optical module assembly method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor laser / optical fiber coupling device for coupling a semiconductor laser unit to an optical fiber.

[0002]

2. Description of the Related Art A conventional optical module assembling method for coupling a semiconductor laser and an optical fiber will be described in detail with reference to the drawings.

FIG. 3 is a flow chart showing an example of a conventional method for coupling a semiconductor laser and an optical fiber, and FIG. 4 is a sectional view showing the structure of a conventional optical module.

In FIG. 4, the conventional optical module is
The package stem 1, the semiconductor laser 2, the monitor light receiving element 3, the electrode 4, the spherical lens 5, and the lens holder 6
, Support 7, ferrule 8, optical fiber strand 9
And a semiconductor laser unit 10.
Then, this structure has a concentric cylindrical shape centered on the optical axis.

3 and 4, in the conventional coupling method, in step 1, the ferrule 8 is finely adjusted in a direction parallel to the optical axis (Z direction) and a direction perpendicular to the optical axis (XY direction) by a manipulator such as a stage. Position, and perform alignment to the place where the maximum coupling efficiency is obtained, and in step 2, support 7
The end face and the end face of the semiconductor laser unit 10 are brought into close contact and pressed, and the ferrule 8 and the support 7 are laser-welded. Then, in step 3, the semiconductor laser unit 10 or the ferrule 8 is moved to lower the support 7 with a force sufficient to align the optical axis, and the support 7 is aligned again at the position where the coupling efficiency is maximum. The high pressing support 7 and the semiconductor laser unit 10 are laser-welded. Next, the problem of co-deviation in step 3 will be described.

FIG. 5 is a side view for explaining co-displacement due to frictional force in step 3 of the conventional example.

Assuming that the applied pressure is F ₁ and the frictional force is F ₂ , the applied pressure F ₁ is 1 kg, and the coefficient of static friction is μ, and if μ is 0.1, the frictional force F ₂ is F ₂ = μF ₁ = 0.1 × 1 = 0.1 kg.

Next, the deflection of the ferrule due to this frictional force will be calculated.

If the shape of the ferrule is outer diameter: φ2 mm, inner diameter: φ1 mm (material: stainless steel), and the distance L from the ferrule clamp point is 7 mm, the deflection δ of the ferrule is δ = F ₂ L ₃ / 3EI = It becomes 7.4 (μm). (Where E is the longitudinal elastic modulus of stainless steel, I
Is the second moment of area of the ferrule)
Then, after the final optical axis adjustment, a maximum residual strain of 7.4 μm remains due to the co-deviation. Since this residual strain is a major factor of the axis deviation during welding in step 4, it is necessary to minimize this residual strain in order to improve the yield.

As an optical axis adjusting method in the state of close contact and pressing, for example, there is JP-A-63-296009.

6 and 7 are plan views for explaining the optical axis adjusting method in the conventional optical module assembly.

When hill climbing is searched alternately in the XY directions, the strain due to the frictional force influences each other. Therefore, stepwise feeding is performed in the X direction to fix the position, and the Y direction is moved at that position to obtain the maximum light amount. By sequentially repeating this, first, the X position where the maximum light amount is obtained is searched.

After that, it moves in the Y direction at the determined X position and stops at the position where the maximum amount of light is obtained, and the optical axis adjustment is completed.

With this optical axis adjusting method, the maximum amount of light can be reliably searched for, but finally distortion remains in the Y direction, and the problem of axis misalignment during welding remains.

[0015]

In the conventional optical module assembling method described above, the step of moving the stage and the like to adjust the optical axis while the support 7 is pressed low in step 3 causes a mutual displacement due to frictional force. However, the residual strain remains, and the optical axis is largely deviated due to the residual strain during the laser welding in step 4.

[0016]

According to another aspect of the present invention, there is provided an optical module assembling method, wherein a semiconductor laser unit is composed of a semiconductor laser and a first fixing member for fixing a lens for collecting light emitted from the semiconductor laser. In an optical module assembly method for assembling a semiconductor laser unit and an optical fiber so as to be fixed by a second fixing member, a first step of adjusting the optical fiber to a position where the coupling efficiency is maximum, and an end face of the second fixing member and a semiconductor The second step of laser welding the second fixing member and the optical fiber by bringing the end surface of the first fixing member of the laser unit into close contact with each other, and releasing the second fixing member from the pressed state, the coupling efficiency is again in the plane. A third step of adjusting to the maximum position, a fourth step of memorizing the planar position in the third step, and a low pressing half with a force sufficient to align the optical axis of the second fixing member. Compare the fifth step of moving the body unit or the optical fiber to the position where the coupling efficiency is maximum again in the plane, and the plane position in the fifth step and the plane position stored in the fourth step. A sixth step of making a decision to proceed to the next step only when the difference between the two-dimensional positions of the two is within a set amount, and to stop the process work when the difference is equal to or more than the set amount; a second fixing member and a semiconductor laser; It is characterized by comprising a seventh step of laser welding the unit and the unit.

[0017]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a flow chart showing an embodiment of an optical module assembling method according to the present invention, and FIG. 2 is a sectional view showing the structure of an optical module of this embodiment.

The optical module of this embodiment has almost the same structure as the conventional optical module shown in FIG.

In FIG. 2, the optical module of this embodiment has a package stem 1, a semiconductor laser 2, a monitor light receiving element 3, an electrode 4, a spherical lens 5, and a lens holder, as in the conventional example. 6, support 7, ferrule 8, optical fiber element wire 9, and semiconductor laser unit 1
The package stem 1, the semiconductor laser 2, the spherical lens 5, and the lens holder 6 constitute a semiconductor laser unit 10, and the optical fiber element wire 9 is fixed to the ferrule 8.

Here, the first fixing member shown in the claims is the lens holder 6, the optical fiber is the optical fiber element wire 9 fixed to the ferrule 8, and the second fixing member. The member is the support 7.

In this embodiment, stainless steel is used as the material for the lens holder 6, support 7 and ferrule 8.

The ferrule 8 is guided by the support 7 with a clearance of about 10 μm, and holds the position of maximum coupling efficiency by finely adjusting in the X, Y, Z directions by a stage or the like.

The support 7 includes a semiconductor laser 2, a lens 5 for condensing light emitted from the semiconductor laser 2, and a semiconductor laser unit 10 composed of a semiconductor laser 2 and a lens holder 6 for fixing the lens 5. , The ferrule 8, the optical fiber strand 9, and the semiconductor laser unit 10 and the ferrule 8, the optical fiber strand 9 are optically parallel and perpendicular,
The semiconductor laser unit 10 is fixed so that the position can be adjusted in the rotation direction.

Next, a method of assembling the optical module of this embodiment will be described with reference to the drawings.

In FIG. 1 and FIG. 2, the ferrule 8 and the optical fiber element wire 9 are aligned at the position where the coupling efficiency is maximum in the process, and the end face of the support 7 and the end face of the lens holder 6 of the semiconductor laser unit 10 are processed in the process. 2 is brought into close contact with the support 7 and the ferrule 8 is spot-laser welded to the portions A and B in FIG. 2 with a YAG laser or the like. In the process
The support 7 is released from the pressed state and is again adjusted to the position where the coupling efficiency is maximum in the plane, and the planar position (XY coordinates: X1, Y1) in the process is stored in the process. In the process, the semiconductor laser unit 10 or the ferrule 8 and the optical fiber element wire 9 are moved by low pressing with a force (about 500 g / cm ² ) enough to align the optical axis of the support 7 and the coupling efficiency is maximized again in the plane. In the process, the XY coordinate value (X ₂ , Y ₂ ) in the process is compared with the XY coordinate value in the previous process, and [(X ₂ −X
₁ ) ² + (Y ₂ −Y ₁ ) ² ] ^1/2 is greater than or equal to the standard set value, the process work is stopped, and only when it is within the standard set amount, the determination is made to proceed to the next process, and the process is performed. Then, press the support 7 with high pressure and the support 7 and the semiconductor laser unit 10
And laser weld.

[0027]

As described above, the optical module assembling method according to the present invention compares the optical axis coordinate value at the time of no load with the optical axis coordinate in the final optical axis adjusting step before the final welding step. , It is possible to quantitatively grasp the residual strain amount caused by the final optical axis adjustment process in the low pressure state, and the final laser welding fixing is performed only for the object held at a low level, so that the final welding caused by the residual strain compared to the conventional method. This has the effect of significantly reducing the axis deviation of.

[Brief description of drawings]

FIG. 1 is a flowchart showing an embodiment of an optical module assembling method according to the present invention.

FIG. 2 is a cross-sectional view showing the configuration of the optical module of this embodiment.

FIG. 3 is a flowchart showing an example of a conventional semiconductor laser / optical fiber coupling method.

FIG. 4 is a cross-sectional view showing a configuration of a conventional optical module.

FIG. 5 is a side view for explaining co-displacement due to a frictional force in step 3 of the conventional example.

FIG. 6 is a plan view for explaining an optical axis adjusting method in a conventional optical module assembly.

FIG. 7 is a plan view for explaining an optical axis adjusting method in a conventional optical module assembly.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Package stem 2 Semiconductor laser 3 Light receiving element for monitor 4 Electrode 5 Ball lens 6 Lens holder 7 Support 8 Ferrule 9 Optical fiber element wire 10 Semiconductor laser unit

Claims (1)

(57) [Claims] 1. A semiconductor laser unit comprises a semiconductor laser and a first fixing member for fixing a lens for converging light emitted from the semiconductor laser, and the semiconductor laser unit and the optical fiber are provided with a second fixing member. In an optical module assembling method of assembling so as to be fixed by a fixing member, a first step of adjusting the optical fiber to a position where coupling efficiency is maximum,
A second step of laser welding the second fixing member and the optical fiber by bringing the end surface of the second fixing member and the end surface of the first fixing member of the semiconductor laser unit into close contact with each other, and the second fixing member. Is released from the pressed state and the coupling efficiency is again adjusted to the position where the coupling efficiency is maximum in the plane, the fourth step of storing the planar position in the third step, and the second fixing member A fifth step of moving the semiconductor unit or the optical fiber by low pressure with a degree of axial alignment to adjust the coupling efficiency to the maximum position again in a plane, and a planar position in the fifth step. A comparison is made with the two-dimensional position stored in the fourth step, and only if the difference in the two-dimensional positions is within a set amount, the process proceeds to the next step, and if it is above the set amount, it is determined that the process work is stopped. Sixth step to perform The second fixing member and the optical module assembling method characterized in that it is composed of a seventh step of the semiconductor laser unit for laser welding.