JP2003021757A - Method for assembling optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that the influence of the dimensional error of fixed parts or the difference in energy of respective laser beams or the like saliently appears undesirebly. SOLUTION: The method is for assembling an optical device in which an optical part and a ferrule in which an optical fiber is inserted and fixed are provided and the ferrule is welded with a laser beam to a fixing part at a position wherein the optical fiber inserted and fixed in the ferrule and the part are optically connected. The focal points of the laser beams are present on the same side, which is either in the foreground side of contact points or the counter side in the direction of the laser beam irradiation when the contact points of the ferrule and the fixed part are irradiated with the laser beams emitted from laser heads and both members are welded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device assembling method.

[0002]

2. Description of the Related Art Conventionally, various optical devices have been developed, one of which is an optical device (LD module) shown in FIG. In the optical device shown in FIG. 6, a light emitting element (laser diode: LD) A and a ferrule C in which an optical fiber B is inserted and fixed are housed in a package D, and the ferrule C is inserted and fixed in the optical fiber B. And the light emitting element A are laser-welded to the fixed part E at a position where they can be optically coupled. When assembling this type of optical device, as shown in FIG.
Out of the contact points with, the two or more contact points (welding points) F facing each other with the optical fiber B inserted and fixed in the ferrule C in between.
Laser welding is applied to the both to laser weld them. At this time, as shown in FIG. 8, the distance between the laser head G that emits laser light and the welding point F is adjusted so that the welding point F and the focal point of the laser light coincide with each other. This is because it was considered that the laser beam had the maximum energy density at its focal point, and that the welding point F melted well.

[0003]

However, in reality, one or both laser heads G are deviated from a predetermined position, or the size of the fixed part E varies.
In many cases, the welding point F and the focal point of the laser beam do not coincide with each other. For example, as shown in FIG. 9, the focus of the laser light emitted from one laser head G coincides with the welding point F, but the focus of the laser light emitted from the other laser head G is beyond the welding point F. May be shifted to the laser head G side (front side). Further, as shown in FIG. 10, the focal point of the laser light emitted from the other laser head G may be shifted to the opposite side (front side) of the laser head G across the welding point F. Here, since the laser beam has the maximum energy density at its focal point, the focal point of one laser beam coincides with the welding point F of one and the focal point of the other laser beam deviates from the welding point F as described above. If so, the difference in energy density of laser light at both welding points F becomes remarkable. Also, for the same reason, 2
When the two laser beams are out of balance (when the energy densities of the laser beams are different or when the shape of the focal point is distorted), the effect thereof is remarkable at the welding point F. Furthermore, when there is a difference in the energy density of the laser light applied to the two welding points F, the ferrule C is pulled toward the welding point F irradiated with the laser light having a higher energy density. As a result, the ferrule C is laterally displaced from the positioned position, and the optical coupling between the light emitting element A (FIG. 6) and the optical fiber B is deteriorated. In particular, when the optical fiber B inserted and fixed in the ferrule C is a lensed fiber, the allowable positional deviation of the ferrule C is extremely small. Therefore, it was very difficult to fix the ferrule C within the range of the allowable positional deviation amount.

[0004]

One of the methods for assembling an optical device of the present application is to provide an optical component and a ferrule having an optical fiber inserted and fixed therein, and the ferrule is an optical fiber inserted and fixed into the optical fiber and the optical fiber. A method for assembling an optical device in which a component and a fixed component are laser-welded to a fixed component at a position where they can be optically coupled to each other. Two or more laser beams emitted from two or more laser heads are provided between the ferrule and the fixed component. When irradiating two or more different contact points of laser light and laser welding them, the focus of each laser beam is the same on either the front side or the opposite side of the laser beam irradiation direction from each contact point position. It is located on the side.

Another one of the optical device assembling methods of the present application is that the laser head and the contact are so arranged that the diameter of the laser light applied to the contact is 1.3 times or more the diameter of the laser light at the focus. It sets the distance between.

Another method of assembling the optical device of the present application is to irradiate each contact with laser light from directly above or obliquely above.

[0007]

(Embodiment 1) The optical device assembling method of the present invention is used, for example, in assembling the optical device shown in FIG. The optical device shown in FIG. 1 is a laser diode module for optical communication (hereinafter referred to as “LD module”) and has the following configuration.

The LD module shown in FIG. 1 has a metal package 1. Base 2 in package 1
Are arranged and fixed, and the light emitting element 4 is arranged and fixed to the fixing portion of the base 2 via the heat sink 3. Further, the front end side of the lensed fiber (optical fiber having a lens formed on the front end surface) 5 is inserted into the package 1 from the insertion portion 6 provided on the side wall of the package 1, and the front end surface 7 having the lens processed is the above-mentioned. It faces the light emitting element 4 in an aligned state. The light emitting element 4 and the front end surface 7 of the lensed fiber 5 face each other at a position where the excitation efficiency (optical coupling efficiency) is maximized. The package 1 has, for example, a CuW bottom plate 8.
And the other portion is formed of an Fe-Ni-Co based alloy. A thermo module 9 for controlling the temperature of the light emitting element 4 is arranged on the bottom plate 8,
The base 2 is arranged and fixed on the thermo module 9.

The first ferrule 13 is fixed to the base 2 through a single fixed part 10 and two separate fixed parts 11 and 12 (only one fixed part 11 is shown in FIG. 1). The tip side of the lensed fiber 5 is inserted and fixed to the first ferrule 13. A second ferrule 14 is arranged on the rear end side of the first ferrule 13 at a distance from the first ferrule 13, and an intermediate part of the lensed fiber 5 is inserted and fixed to the second ferrule 14. The second ferrule 14 is inserted into the insertion portion 6 of the package 1. The second ferrule 14 is fixed to the side wall of the package 1 via a ferrule fitting portion 15 provided in the package 1. The surface of the lensed fiber 5 between the first ferrule 13 and the second ferrule 14 is metal-plated. One end of the metal plated portion 16 is fixed to the second ferrule 14 by the solder 17, and the second ferrule 14 is the solder 1
It is fixed to the ferrule fitting portion 15 by 8. That is, the metal plated portion 16 of the lensed fiber 5 is fixed to the second ferrule 14 by soldering, and the second ferrule 14
Is fixed to the ferrule fitting part 15 by soldering,
The inside of the package 1 is airtight.

The LD module having the above structure is assembled by the optical device assembling method of the present invention as follows. However, in the optical device assembling method of the present invention, the first ferrule 13 is fixed to the fixed component 10 and the fixed component 1.
Since it has a feature in the step of fixing to Nos. 1 and 12, only this step will be described, and description of other steps will be omitted. (1)
As shown in FIGS. 2A and 2B, the first ferrule 1
The joint end face of 3 is set between the pair of opposing arms 20 and 21 of the fixed component 10. Here, the first ferrule 13 has a cylindrical shape whose height direction is in the optical axis direction (Z axis direction). In addition, the pair of arms 20 of the fixed component 10,
Reference numerals 21 and 21 face each other at substantially the same intervals as the diameter of the first ferrule 13, and the arms 20 and 21 have flat upper surfaces 20a and 21a including the X axis and the Z axis, respectively. Therefore,
When the first ferrule 13 is set between the arms 20 and 21, the ferrule 13 is held between the arms 20 and 21. At this time, contacts 22 and 23 are formed between the cylindrical side surface of the first ferrule 13 and the upper surfaces 20a and 21a of the arms 20 and 21, respectively. The first ferrule and the arms 20 and 21 are not in strict contact with each other at the contact points 22 and 23, and there is a slight gap (several to several tens of μm) between them. However, in this specification, such a case is also referred to as a contact for convenience of description. (2) The position of the first ferrule 13 is adjusted so that the lensed fiber 5 inserted through and fixed to the ferrule 13 and the light emitting element 4 (FIG. 1) are aligned. Specifically, the lensed fiber 5 and the light emitting element 4 are aligned so that the excitation efficiency (optical coupling efficiency) between the two is maximized. (3) Each arm 2 shown in FIGS. 2 (a) and 2 (b)
Contact point (welding point) between 0 and 21 and the first ferrule 13 2
Laser light (for example, YAG laser) is simultaneously irradiated to the Nos. 2 and 23 from obliquely above, and both are laser-welded. At this time, the distance between each laser head and each of the welding points 22 and 23 is adjusted in advance so that the focus of the laser light applied to the welding points 22 and 23 deviates from the welding points 22 and 23. Specifically, as shown in FIG. 3, the laser head 30, so that the focus of the laser light is located on the laser head 30, 31 side (front side) with respect to the welding points 22, 23.
The distance between 31 and the welding points 22 and 23 is adjusted.
Alternatively, as shown in FIG. 4, the laser head 30, such that the focus of the laser light is located on the opposite side (front side) to the laser heads 30, 31 with the welding points 22, 23 interposed therebetween.
The distance between 31 and the welding points 22 and 23 is adjusted.
Here, the first ferrule and each arm 20, 21 are not in strict contact with each other at the welding points 22, 23, but when the welding point 22, 23 is irradiated with laser light, the first ferrule 13 and each arm A bridge portion is formed between 20 and 21. (4) The rear portion of the first ferrule 13 is shaken with the bridge portion as a fulcrum to swing the first ferrule 13 and the light emitting element 4
And align again. (5) As shown in FIGS. 5A and 5B, the rear part of the first ferrule is provided with two fixing parts 11,
12 holds them from both outsides. Here, the respective fixed parts 11 and 12 also have a flat upper surface 11a including the X axis and the Z axis,
12a. Therefore, when the first ferrule 13 is sandwiched and held by both fixing parts 11 and 12, contacts 24 and 25 are formed between the cylindrical side surface part of the ferrule 13 and the upper surfaces 11a and 12a of the fixing parts 11 and 12, respectively. .
The fixed parts 11 and 12 strongly press the first ferrule 13 from both sides at the contacts 24 and 25, and there is no gap between them. (6) The two laser beams emitted from the two laser heads are simultaneously irradiated onto the contacts 24 and 25 from diagonally above. As a result, the first ferrule 1
3 and the fixed parts 11 and 12 are welded and fixed in the same manner as the fixed part 10 side. Also at this time, as shown in FIG. 3 or FIG. 4, the laser heads 30 and 31 and the welding points 24 are arranged so that the focal points of the laser beams applied to the welding points 24 and 25 deviate from the welding points 24 and 25. , 25 is adjusted in advance.

As described above, in the optical device assembling method according to the present invention, the focal points of the two laser beams simultaneously irradiated to the welding points 22 and 23 or 24 and 25 are both irradiated in the irradiation direction more than the welding points 22 to 25. Remove it on the same side, either the front side or the opposite side. As a result, even if the energy density of the laser light emitted from the respective laser heads 30 and 31 is different or the focal point shape is distorted, their influence at the welding points 22 to 25 is reduced. In particular, it is possible to suppress the variation in the amount of solidification shrinkage due to welding between the welding points 22 and 23 or the welding points 24 and 25 to which the laser light is simultaneously irradiated. Further, there is an error in the size of the fixed parts 10, 11, 12 (in particular, the size in the Y-axis direction shown in FIGS. 2 and 5), and the distance between the laser heads 30, 31 and the welding points 22-25 is small. Even if they change a little, those welding points 22
A large difference will not occur in the energy density of the laser light irradiated to ˜25. Further, assuming that the shape of the laser beam applied to each of the welding points 22 to 25 is a perfect circle, the area is πr ² (r: radius of the laser beam applied to the welding point), and the light energy per unit area is Density is E / π
r ² . Therefore, the focus of the laser beam is set at each welding point 22.
~ 25 to remove those welding points 22-25
If the radius of the laser light irradiated on the laser light is increased, the density becomes almost the same even if the light energy amount of the laser light is slightly different. From the above viewpoints, each welding point 22
The laser head 30, so that the diameter of the laser beam applied to the laser beam is about 1.3 times the diameter at the focal point,
It is desirable to adjust the distance between 31 and each welding point 22 to 25 (the laser heads 30 and 31 are moved closer to or away from each welding point 22 to 25).

In the present embodiment, the laser is applied obliquely from above to the contact points of the two parts (ferrule and fixed part) to be laser-welded. When the contact point and the irradiation direction of the laser beam applied to the contact point are in such a relationship, the processing accuracy of one or both parts has a great influence on the fixing accuracy by laser welding. In particular, the two fixing parts 11, 1
Since 2 is a separate body, the sizes of the two are often different, and this dimensional error may deteriorate the fixing accuracy by laser welding. However, according to the present invention in which the focus of the laser light is off the contact point, it is possible to reduce the deterioration of the fixing accuracy due to the processing accuracy of the component.

In the present embodiment, a slight gap is provided between the first ferrule 13 and the fixed component 10 at the contacts 22 and 23, thereby making it possible to re-align the ferrule 13. In this case, lateral gap (positional shift in the X-axis direction in FIG. 2) is likely to occur in the first ferrule 13 due to the gap. However, according to the present invention in which the focus of the laser light is off the contact, the lateral deviation can be effectively suppressed. Also, the first of the contacts 24, 24
Although there is no gap between the ferrule 13 and the fixed parts 11 and 12, the same lateral displacement as described above may occur.
However, according to the present invention, this lateral displacement can be effectively suppressed.

Of the steps necessary for assembling the optical device shown in FIG. 1, steps other than the above steps may be existing steps or new steps including new elements. The optical component that can be optically coupled to the optical fiber may be an optical component other than the light emitting element. However, in the case where the optical component is a light emitting element and the optical fiber is a lensed fiber which is inserted and fixed in the ferrule, high positioning accuracy is required for both, and therefore the positional deviation of the ferrule is caused by the optical device assembling method of the present invention. It is desirable to prevent

[0015]

According to the optical device assembling method of the present application, two laser beams emitted from two or more laser heads are respectively applied to two or more different contact points between the ferrule and the fixed part, and both are laser-welded. In doing so, the focus of each laser beam is removed from each contact, so that the following effects are obtained. That is, the laser light has the maximum amount of light energy at its focal point. Therefore, if the focus of the laser light is removed from the contact point between the ferrule and the fixed component, even if the output of each laser head varies, the energy density of the laser light applied to each contact point does not greatly differ. In addition, even if the distance between each laser head and each contact changes slightly due to the dimensional error of the fixed component, the influence thereof is reduced.
Further, even if the focal shape of the laser light is distorted, the influence does not appear remarkably at the contact. Due to the above effects, the energy density of the laser light applied to each contact is substantially uniform. Therefore, the ferrule does not laterally shift due to the difference in the energy density of the laser light applied to each contact, and the ferrule is fixed at the prepositioned position.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of an optical device assembled by an optical device assembling method of the present invention.

FIG. 2A is a plan view showing a state in which the tip side of a ferrule is set on a fixed component, and FIG. 2B is a side view of the same.

FIG. 3 is an explanatory view showing a state in which a laser beam is applied to a welding point between a ferrule and a fixed part, and a case where a focus of the laser beam is set in front of the welding point.

FIG. 4 is an explanatory view showing a state in which a laser beam is applied to a welding point between a ferrule and a fixed component, and a case where the focus of the laser beam is set to the tip of the welding point.

5A is a plan view showing a state in which a rear end side of a ferrule is set on a fixed component, and FIG. 5B is a side view of the same.

FIG. 6 is an explanatory diagram showing an example of an optical device.

7 is a plan view showing a state in which the ferrule shown in FIG. 6 is set in the fixed part shown in FIG.

FIG. 8 is an explanatory view showing a state where the contact point between the fixed component and the ferrule is irradiated with laser light, and is a view in the case where the focal point of the laser light and the contact point coincide with each other.

FIG. 9 is an explanatory view showing a state in which a laser beam is applied to the contact point between the fixed part and the ferrule, and is a diagram in the case where the focus of the laser beam is shifted toward the front side of the contact point.

FIG. 10 is an explanatory diagram showing a state where a contact point between the fixed component and the ferrule is irradiated with laser light, in which the focus of the laser light is displaced ahead of the contact point.

[Explanation of symbols]

1 package 2 base 3 heat sink 4 light emitting elements 5 Optical fiber (lensed fiber) 6 Insert 7 Optical fiber tip surface 8 bottom plate 9 Thermo module 10 Fixed parts 11 Fixed parts 12 Fixed parts 13 First Ferrule 14 Second Ferrule 15 Ferrule fitting part 16 Metal plating part 17 Solder 18 Solder 20 arms 21 arms 22-25 Welding point between fixed part and ferrule 30 laser head 31 laser head

Claims (3)

[Claims] 1. A ferrule having an optical component and an optical fiber inserted and fixed, wherein the ferrule is laser-welded to the fixed component at a position where the optical fiber inserted and fixed to the optical component can be optically coupled. A method for assembling an optical device, wherein two or more laser beams emitted from two or more laser heads are applied to two or more different contact points between a ferrule and a fixed part to laser-weld both. In addition, the optical device assembling method is characterized in that the focal point of each laser beam is located on the same side of either the front side or the opposite side of the laser beam irradiation direction with respect to each contact point position. 2. The distance between the laser head and the contact is set such that the diameter of the laser light applied to the contact is 1.3 times or more the diameter of the laser light at the focal point. The optical device assembling method according to claim 1. 3. The optical device assembling method according to claim 1, wherein each contact is irradiated with laser light from directly above or obliquely above.