WO2012169275A1

WO2012169275A1 - Method for fixing optical fiber, and method for manufacturing laser module

Info

Publication number: WO2012169275A1
Application number: PCT/JP2012/059151
Authority: WO
Inventors: 洋平葛西
Original assignee: 株式会社フジクラ
Priority date: 2011-06-07
Filing date: 2012-04-04
Publication date: 2012-12-13
Also published as: JP2012255846A; JP5111644B2

Abstract

A method for fixing an optical fiber according to the present invention includes a step (S103) for melting a solder preform (103) located on one side of an optical fiber (101) by means of heat transfer from a laser irradiated area (102b) on a fiber mount (102), where the distance (H) between the surface of the optical fiber (101) and the upper surface of the fiber mount (102), the diameter (D) of the optical fiber (101), and the height (L) of the solder preform (103) satisfy the following formula: H + D < L.

Description

Optical fiber fixing method and laser module manufacturing method

The present invention relates to an optical fiber fixing method. More specifically, the present invention relates to a fixing method for fixing an optical fiber to a support member using solder. The present invention also relates to a method for manufacturing a laser module.

Laser devices using laser elements such as semiconductor laser (LD) elements have been commercialized and are widely used in the field of optical communications. As an example of such a laser apparatus, there is a laser module that combines a laser element and an optical fiber. In such a laser module, it is required to combine the laser element and the optical fiber so as to be optically coupled with a high optical coupling rate.

For this reason, in such a laser module, the emission surface of the laser element (the surface from which the laser light is emitted) and the tip of the optical fiber so that more laser light emitted from the laser element is introduced into the optical fiber. Therefore, it is important to accurately maintain the positions of the emission surface of the laser element and the tip of the optical fiber in the aligned state. Particularly in recent years, high-power semiconductor laser elements such as those for processing have become widespread. However, since these laser elements have a low coupling efficiency with an optical fiber, the laser device is damaged by leakage light. The alignment with the fiber is extremely important.

Normally, the optical fiber is aligned with the laser element fixed on the laser mount, and the optical fiber is fixed on the fiber mount (support member) in the aligned state. For this reason, it is required to fix the optical fiber on the fiber mount while maintaining high positional accuracy.

Patent Document 1 discloses a solder preform 200 in which a groove 212 is formed as shown in FIG. FIG. 10B is a front view of the solder preform 200 disposed on the upper surface (not shown) of the fiber mount and the optical fiber 214 disposed in the groove 212 of the solder preform 200. In this state, the laser preform 215 is irradiated onto the solder preform 200, and the solder preform 200 is melted and re-solidified, whereby the optical fiber 214 is fixed to the fiber mount.

As shown in FIG. 10B, the groove 212 is formed so that the optical fiber 214 does not contact the body 201 of the solder preform 200. Accordingly, the optical fiber 214 is not brought into contact with or pulled by the body 201 before the solder preform 200 is melted by irradiating the laser 215, so that the position when the optical fiber 214 is fixed on the laser mount. The generation of errors can be suppressed. Further, since the laser beam 215 is not directly irradiated onto the optical fiber 214, the optical fiber 214 can be prevented from being damaged by the laser beam 215.

Patent Document 2 discloses a method of fixing an optical fiber 2 to a fixing base 6 (corresponding to a fiber mount) in which an upper concave structure 63 and a lower concave structure 62 are formed, as shown in FIG. Yes. In this fixing method, first, in a state where the optical fiber 2 is fitted in the lower concave structure 62, the solder 3 is placed on the upper concave structure 63, and the laser beam 4 is irradiated so as not to directly irradiate the optical fiber 2. Also in this fixing method, since the laser beam 4 is not directly irradiated onto the optical fiber 2, the optical fiber 2 can be prevented from being damaged by the laser beam 4. Further, as shown in FIG. 11B, since the optical fiber 2 is fixed in a state of being positioned by the lower concave structure 62, occurrence of a position error when the optical fiber 2 is fixed to the fixing base 6 is suppressed. be able to.

Japanese Patent Publication “Japanese Patent Laid-Open No. 2005-122129 (published May 12, 2005)” Japanese Patent Publication “Japanese Patent Laid-Open Publication No. 62-19811 (published Jan. 28, 1987)”

As described above, conventionally, at least one of the solder preform and the fiber mount is processed into a special shape, thereby suppressing the occurrence of a position error that may occur when the optical fiber is fixed on the fiber mount. It was.

On the other hand, Au80Sn20 is most frequently used as a solder for fixing an optical fiber in a high-power laser module whose demand is increasing in recent years. Au80Sn20 is a high-melting-point lead-free solder and has a high reliability of solder fixing. However, it has the aspect that brittle collapse is likely to occur and processing is difficult. For this reason, as described in Patent Document 1, it is not easy to form the groove 212 in the solder preform 200, which causes problems such as a decrease in yield and an increase in cost.

In addition, the method described in Patent Document 2 requires a step of forming a groove on the upper surface of the fiber mount before the step of fixing the optical fiber to the fiber mount, thereby increasing the number of steps and increasing the cost. I will be invited.

Also, in a semiconductor laser module, solder is usually used in a fluxless manner so as not to reduce the reliability of the laser element. However, since fluxless is used, an oxide film and solder originally present on the solder surface are not present. There is a problem that the oxide film formed on the surface of the solder when melted cannot be removed, the wettability of the solder is lowered, and the reliability of the solder fixing is easily lowered. In the techniques disclosed in Patent Document 1 and Patent Document 2, since the laser beam is directly irradiated onto the solder, the solder surface temperature at the location where the laser beam is hit is locally much higher than the melting point, The formation rate of the oxide film is remarkably increased. Therefore, there is a problem that solder wettability cannot be improved and it is not easy to perform highly reliable solder fixing.

The present invention has been made based on the knowledge obtained by the inventor in view of the above problems, and an object thereof is an optical fiber capable of performing highly reliable solder fixing while suppressing cost. It is to realize the fixing method.

In order to solve the above problems, an optical fiber fixing method according to the present invention is an optical fiber fixing method for fixing an optical fiber to a support member, and the optical fiber is disposed along an upper surface of the support member. A holding step for holding, a placing step for placing a solder preform made of fluxless solder on the upper surface of the support member, and a laser light irradiation region set on the surface of the support member is irradiated with laser light. A melting step of melting the solder preform by heat conduction from the laser beam irradiation region, and the solder preform placed in the placing step is held in the holding step. The distance between the surface of the optical fiber that is located on one side of the optical fiber and held in the holding step and the upper surface of the support member is H, and the optical fiber The diameter is D, when the height of the solder preform is placed at the top the placing step is L, and satisfies the H + D <L, it is characterized in that.

According to the optical fiber fixing method, the solder preform placed in the placing step is sufficient if it is located on one side of the optical fiber held in the holding step. The shape of the solder preform need not be a shape that straddles the optical fiber, and there is no need to form a recess in the support member. For this reason, the shape of the solder preform and the fiber mount can be simplified. Therefore, the processing cost of the solder preform and the support member can be saved, and the cost is suppressed.

Further, according to the above-described optical fiber fixing method, since the solder preform made of fluxless solder is used, the reliability is lowered due to the flux adsorbing to the optical fiber and the optical element that can be arranged around the optical fiber. And soldering can be performed.

Further, according to the optical fiber fixing method, the laser light irradiation region set on the surface of the support member is irradiated with laser light, and the solder preform is melted by heat conduction from the laser light irradiation region. Therefore, the solder oxidation that may occur when the laser beam is directly irradiated onto the solder preform is not caused, and the reliability of the solder fixing is improved. Furthermore, since the molten solder is supplied onto the surface of the heated support member, the wettability of the solder is increased as compared with the case where the support member is not heated. Solder fixation can be performed.

In addition, according to the above optical fiber fixing method, the solder preform formed as a single piece is melted, so that the solder to be melted is compared with a method of melting only a part of the thread solder wound around the reel, for example. Can be kept at the desired amount. For this reason, highly reliable solder fixation is possible. Further, since a device for sending out the thread solder wound around the reel is unnecessary, the cost can be suppressed.

Further, the distance between the surface of the optical fiber held in the holding step and the upper surface of the support member is H, the diameter of the optical fiber is D, and the solder plug placed in the placing step is used. When the height of the reform is L, since H + D <L is satisfied, the melted solder flows vigorously between the optical fiber and the support member due to gravity, and wraps the optical fiber. Thereby, soldering with high reliability can be performed.

The distance between the surface of the optical fiber and the upper surface of the support member refers to the shortest distance from the surface of the optical fiber to the upper surface of the support member. In addition, “holding the optical fiber along the upper surface of the support member” may hold the optical fiber separated from the surface of the support member, or may hold the optical fiber of the support member. It means that it may be held in contact with the surface.

A method for manufacturing a laser module according to the present invention is a method for manufacturing a laser module including an optical fiber and a support member for supporting the optical fiber, and uses the optical fiber fixing method. The optical fiber and the support member are fixed.

According to the above manufacturing method, it is possible to manufacture a laser module using highly reliable solder fixing while suppressing cost.

As described above, according to the optical fiber fixing method of the present invention, it is possible to stably perform highly reliable solder fixing while suppressing costs.

It is a figure for demonstrating the optical fiber fixing method which concerns on embodiment of this invention, Comprising: (a) is a perspective view which shows arrangement | positioning of an optical fiber, a fiber mount, and a solder preform, (b) It is sectional drawing along the surface perpendicular | vertical to the extending direction of an optical fiber of an optical fiber, a fiber mount, and a solder preform. It is a flowchart which shows the process included in the optical fiber fixing method which concerns on embodiment of this invention. FIGS. 5A and 5B are diagrams for explaining an optical fiber fixing method according to an embodiment of the present invention, wherein FIGS. It is a figure which shows a mode that solder preform melt | dissolves and resolidifies after irradiation over time. It is a figure which shows the specific example of the shape of the solder preform which can be used for the optical fiber fixing method which concerns on embodiment of this invention, Comprising: (a) has shown the plate-shaped solder preform, (b) Indicates a cylindrical solder preform. It is a table | surface which shows the specific example of the shape of a solder preform, Comprising: The size about each shape (Cylinder 1, Column 2, board 1, board 2) of a solder preform is represented by C / H (mm) and S / V It is a table | surface shown with each value of (mm ^<-1> ). FIGS. 5A and 5B are diagrams for explaining an optical fiber fixing method according to an embodiment of the present invention, in which FIGS. 5A and 5B show the shape of a solder preform, respectively. 3 is a real photograph showing the shape of solder after re-solidification in the case of “Cylinder 1”, “Cylinder 2”, “Plate 1”, and “Plate 2” shown in FIG. It is a figure which shows the principal part structure of a semiconductor laser module as one application object of the optical fiber fixing method which concerns on embodiment of this invention. FIGS. 8A and 8B are diagrams for explaining an optical fiber fixing method according to a modification of the embodiment of the present invention, wherein FIGS. It is a figure which shows a procedure. FIGS. 5A and 5B are diagrams for explaining an optical fiber fixing method according to a modification of the embodiment of the present invention, wherein FIGS. It is a figure which shows a mode that a solder preform melt | dissolves and resolidifies with progress of time. It is a figure for demonstrating the solder fixation of patent document 1, Comprising: (a) has shown the solder preform in which the groove | channel was formed, (b) is on the upper surface (not shown) of a fiber mount. It is a front view of the optical fiber arrange | positioned in the solder | pewter preform arrange | positioned and the groove | channel of a solder preform. It is a figure for demonstrating the solder fixation of patent document 2, Comprising: (a) is the fixed base in which the upper concave structure and the lower concave structure were formed, and the optical fiber fitted by the lower concave structure It is sectional drawing which shows the state before laser beam irradiation, (b) is sectional drawing which shows the state after laser beam irradiation.

An embodiment of the present invention will be described with reference to FIGS. 1 to 9 as follows.

In the following description, of the six surfaces constituting the plate-like member, two surfaces having the largest area are also expressed as “main surface”, and four surfaces excluding the main surface are also expressed as “end surfaces”. When it is necessary to distinguish two main surfaces from each other, one main surface is expressed as “upper surface” and the other main surface is expressed as “lower surface”. Here, the upper surface refers to the main surface facing upward when the apparatus including the plate member is in a normal installation state, and the lower surface is when the apparatus including the plate member is in a normal installation state. Refers to the main surface facing downward.

FIG. 1A is a diagram for explaining an optical fiber fixing method according to this embodiment, and is a perspective view showing the arrangement of the optical fiber 101, the fiber mount 102, and the solder preform 103. FIG. As shown in FIG. 1A, the optical fiber 101 is held along the upper surface of the fiber mount 102, and a solder preform 103 is placed on one side thereof.

The optical fiber fixing method according to the present embodiment is a method for fixing an optical fiber (optical fiber 101 in FIG. 1A) to a support member (fiber mount 102 in FIG. 1A) using solder. It is. The specific material of the fiber mount 102 is not limited to this embodiment, but is preferably a material that easily absorbs the wavelength of a laser beam 300 to be described later, and is a material having low thermal conductivity. preferable. Examples of such materials include ZrO ₂ (zirconia). By using such a material having low thermal conductivity, there is an advantage that the solder can be fixed easily. On the other hand, materials having high thermal conductivity such as Cu (copper), AlN (aluminum nitride), and CuW (copper tungsten) can also be used. By using such a material having high thermal conductivity, there is an advantage that heat generated by absorbing leakage light generated when the laser module is driven can be easily released.

The specific composition of the solder preform 103 is not limited to this embodiment, but high melting point lead-free solder such as Au80Sn20 (gold 80 tin 20) can be used. Further, as the solder preform 103, it is preferable to use fluxless solder. Thereby, solder fixation can be performed without inviting a decrease in reliability due to the flux adsorbing to the optical fiber 101 and the optical elements that can be disposed in the vicinity thereof.

FIG. 1B is a cross-sectional view of the optical fiber 101, the fiber mount 102, and the solder preform 103 along a plane perpendicular to the extending direction of the optical fiber 101.

In FIG. 1B, H represents the shortest distance from the upper surface of the fiber mount 102 to the surface of the optical fiber 101, D represents the diameter of the optical fiber 101, and L represents a solder preform. The height of 103, that is, the length of the solder preform 103 along the direction orthogonal to the upper surface of the fiber mount 102 is shown. As shown in FIG. 1B, the inequality H + D <L is satisfied in the present embodiment. Since this inequality is satisfied, as will be described later, the molten solder flows vigorously between the optical fiber 101 and the fiber mount 102 due to gravity, and wraps the optical fiber 101. Further, U in FIG. 1B represents a separation distance between the optical fiber 101 and the solder preform 103.

Note that specific values of D, H, and U do not limit the present embodiment. For example, D = 125 μm (micrometer), H = 150 μm, and U = 100 to 150 μm. However, the optimum value of U can generally depend on the size of the metallized region set on the upper surface of the fiber mount 102 described later. U = 100 to 150 μm is suitable when the size of the metallized region is 0.8 mm × 0.8 mm. When the size of the metallized region is larger, the value of U is larger. Also good. Moreover, in the optical fiber fixing method according to the present embodiment, it is preferable to keep the value of U constant. That is, it is preferable to use the same value for U even in a situation where a plurality of optical fibers 101 are fixed to a plurality of fiber mounts 102 at the time of mass production. Thereby, since the amount of displacement of the fiber when the molten solder wraps the optical fiber 101 can be kept constant, variations in fixing accuracy can be suppressed.

Further, as shown in FIGS. 1A to 1B, a metallized region is set on the upper surface of the fiber mount 102, and a metallized layer 102a is attached to the metallized region. Similarly, a metallized layer 101a is deposited on a portion of the surface of the optical fiber 101 corresponding to the metallized region.

The metallized

layers

102a and 101a are both metal thin films, and are formed using, for example, a sputtering method or electroless plating. Although the material which comprises a metallization layer does not limit this embodiment, Au (gold), Pt (platinum), Ti (titanium), Ni (nickel) etc. can be used. By applying the metallized

layers

102a and 101a, the melted solder is easily spread by wetting, so that the reliability of fixing by the solder can be improved. Note that the thickness of the metallized

layers

102a and 101a is sufficiently smaller than D and L described above.

Further, as shown in FIGS. 1A and 1B, a laser beam irradiation region 102b is set on the upper surface of the fiber mount 102, and the laser beam 300 is irradiated to the laser beam irradiation region 102b. Is done. Due to the heat conduction from the laser irradiation region 102b that has been irradiated with the laser beam 300 and the temperature has increased, the temperature of the lower portion of the solder preform 103 rises and the solder preform 103 melts.

Thus, in this embodiment, since the laser beam is not directly irradiated onto the solder preform, the oxidation of the solder is suppressed and the optical fiber can be fixed with high reliability. Further, it is possible to reduce a risk that the optical fiber is accidentally irradiated with the laser light and the optical fiber is damaged. Furthermore, since the solder preform is melted by heat conduction from the laser beam irradiation region 102b, the melting temperature can be easily controlled, and the yield can be improved. Furthermore, since the molten solder is supplied onto the surface of the heated fiber mount 102, the wettability of the solder is increased as compared with the case where the fiber mount 102 is not heated. Soldering can be performed.

In this embodiment, since the solder preform 103 formed as a single piece is melted, the amount of solder to be melted is smaller than, for example, a method in which only a part of thread solder wound on a reel is melted. The desired amount can be kept. Thereby, highly reliable solder fixation can be performed. Further, since a device for sending out the thread solder wound around the reel is unnecessary, the cost can be suppressed.

As shown in FIGS. 1A to 1B, the laser light irradiation region 102b is set on the upper surface of the fiber mount 102 on the side opposite to the optical fiber 101 when viewed from the solder preform 103. Is preferred. Thereby, the heat generated by the laser beam can be effectively used to melt the solder.

FIG. 2 is a flowchart showing steps included in the optical fiber fixing method according to the present embodiment. As shown in FIG. 2, the optical fiber fixing method according to the present embodiment includes the following steps.

(Step S101)
The optical fiber 101 is held along the upper surface of the fiber mount 102.

(Step S102)
The solder preform 103 is placed on the upper surface of the fiber mount 102.

(Step S103)
The laser irradiation region 102b on the surface of the fiber mount 102 is irradiated with the laser beam 300, and the solder preform 103 is melted by heat conduction from the laser irradiation region 102b whose temperature has been increased by irradiation with the laser beam 300.

Here, in the optical fiber fixing method according to the present embodiment, the optical fiber 101 is held along the upper surface of the fiber mount 102 (step S101), and then the solder preform 103 is placed on the upper surface of the fiber mount 102 ( The optical fiber 101 may be held along the upper surface of the fiber mount 102 (step S101) after the solder preform 103 is placed on the upper surface of the fiber mount 102 (step S102). .

When the optical fiber 101 is fixed after being aligned with a laser element (for example, a semiconductor laser chip 33 to be described later), the optical fiber fixing method according to the present embodiment is performed before performing the step S103. A step of aligning the optical fiber 101 with respect to the laser element may be included.

Also, the solder preform 103 placed in step S102 is positioned on one side of the optical fiber 101 held in step S101, as shown in FIGS. In other words, in this embodiment, it is sufficient that the solder preform 103 is placed on one side of the optical fiber 101. Therefore, it is necessary to make the shape of the solder preform 103 so as to straddle the optical fiber 101. There is no need to form a recess in the fiber mount 102. For this reason, the shapes of the solder preform 103 and the fiber mount 102 can be simplified. This is a great advantage when Au80Sn20 or the like that easily causes brittle collapse is used as the solder preform 103. Moreover, since the processing cost of the solder preform 103 and the fiber mount 102 can be saved, the cost is suppressed.

3 (a) to 3 (e) show how the solder preform melts and re-solidifies as time elapses after the laser irradiation region 102b on the surface of the fiber mount 102 is irradiated in step S103. FIG.

As shown in FIG. 3A, when the laser irradiation region 102b is irradiated with the laser beam 300, the temperature below the solder preform 103 exceeds the melting point due to heat conduction from the laser irradiation region 102b. As shown in b), the solder preform 103 starts to melt from the lower part. The melted lower part begins to spread along the upper surface of the metallized layer 102a. Thereafter, the temperature of the upper portion of the solder preform 103 exceeds the melting point due to heat conduction, and the upper portion is directed to the fiber mount 102 due to gravity while changing to a spherical shape due to the influence of surface tension, as shown in FIG. Fall. In this way, the entire solder preform 103 is melted. The melted solder begins to be deformed into a substantially hemispherical shape to minimize its surface area due to the influence of surface tension, and starts to envelop the optical fiber 101 as shown in FIG. Thereafter, as shown in FIG. 3E, the solder that wraps around the optical fiber 101 and becomes substantially hemispherical is solidified again when the heating by the laser beam 300 is finished and the temperature of the fiber mount 102 falls below the solder melting point. . (Hereinafter, the re-solidified solder is also referred to as solder 103 '). Thereby, the optical fiber 101 is fixed on the fiber mount 102.

Subsequently, a preferable shape and size of the solder preform 103 will be described with reference to FIGS. 4 (a) to (b) to FIGS. 6 (a) to (d). The preferable shape and size of the solder preform 103 described below are based on the inventor's knowledge obtained by repeating experiments.

FIGS. 4A to 4B show specific examples of the shape of the solder preform 103 in the present embodiment. As shown in FIG. 4A, a plate-like thing may be used as the solder preform 103, and a cylindrical thing may be used as shown in FIG. 4B.

It is preferable that the shape and size of the solder preform 103 satisfy the following (Condition 1) and (Condition 2).

(Condition 1): S ÷ V <Th1
Here, S (mm ² ) (square millimeter) and V (mm ³ ) represent the surface area and volume of the solder preform 103, respectively, and Th1 = 16.5 (mm ⁻¹ ).

(Condition 2): C ÷ H> Th2
Here, C (mm ² ) and H (mm) represent the contact area where the solder preform 103 and the fiber mount 102 are in contact with each other, and the height of the solder preform, respectively, and Th2 = 0.05. (Mm).

FIG. 5 is a table showing each value of size, C ÷ H (mm), and S ÷ V (mm ⁻¹ ) for each shape (column 1, column 2, plate 1, plate 2) of the solder preform 103. It is. In FIG. 5, the metallized area of the fiber mount 102 is approximately 0.8 mm × 0.8 mm. As shown in FIG. 5, “Cylinder 1” and “Plate 1” both satisfy Condition 1 and Condition 2. On the other hand, “Cylinder 2” does not satisfy Condition 2, and “Plate 2” does not satisfy Condition 1.

6 (a), 6 (b), 6 (c), and 6 (d) respectively show the shapes of the solder preforms 103 as “column 1”, “column 2”, “plate 1”, and FIG. FIG. 6 is a real photograph showing the shape of solder after re-solidification in the case of “plate 2”. 6A and 6C are top views of the solder, and FIGS. 6B and 6D are perspective views of the solder. In FIGS. 6A to 6D, the shape of the metallized region on the fiber mount 102 is a square.

As shown in FIG. 6B, when the shape of the solder preform 103 is “column 2”, unmelted solder preform 103 is generated. This is because the shape and size of the “column 2” do not satisfy the condition 2. More specifically, since the contact area C is small although the height H of the solder preform 103 is large, heat from the laser irradiation region 102b is not sufficiently transmitted to the upper part of the solder preform 103, and unmelted portions are generated. It is.

If the solder preform 103 remains unmelted, the movement of the optical fiber 101 when the solder re-solidifies cannot be controlled, and the fixing accuracy of the optical fiber 101 decreases. In addition, since the solder re-solidifies with the thermal stress (distortion) due to the influence of the unmelted portion of the solder preform 103, when the re-solidified solder is heated by the influence of leakage light or the like, The thermal stress is released and the optical fiber 101 is misaligned. Such a problem becomes conspicuous when an optical fiber is fixed in a laser module using a semiconductor laser having a high output (specifically, for example, 5 W or more). This is because in such a high-power laser module, the intensity of leakage light is strong, and the re-solidified solder is easily heated. As will be described later, if the shape and size of the solder preform 103 satisfy the above condition 2, such a problem does not occur.

In addition, as shown in FIG. 6D, when the shape of the solder preform 103 is “plate 2”, the shape of the solder after re-solidification is asymmetrical with respect to the extending direction of the optical fiber 101. End up. This is because the shape and size of the “plate 2” do not satisfy the condition 1. More specifically, since the surface area S is large although the volume V of the solder preform 103 is small, the wettability of the solder is lowered due to the influence of the oxide film formed on the surface of the solder, and the solder has an asymmetrical shape. This is because it resolidifies as it is.

When the shape of the solder after re-solidification becomes asymmetrical with respect to the extending direction of the optical fiber 101, the movement of the optical fiber 101 when the solder re-solidifies cannot be controlled, and the fixing accuracy of the optical fiber 101 is reduced. Resulting in. In addition, as a result of being asymmetrical, the solder re-solidifies with thermal stress (strain). Therefore, when the re-solidified solder is heated by the influence of leakage light, the thermal stress is It is opened, and the axis deviation of the optical fiber 101 occurs. Such a problem becomes conspicuous when an optical fiber is fixed in a laser module using a semiconductor laser having a high output (specifically, for example, 5 W or more). This is because in such a high-power laser module, the intensity of leakage light is strong, and the re-solidified solder is easily heated. As will be described later, if the shape and size of the solder preform 103 satisfy the above condition 1, such a problem will not occur.

On the other hand, as shown in FIGS. 6A and 6C, when the shape of the solder preform 103 is “column 1” and “plate 1” satisfying both conditions 1 and 2, The shape of the solder is symmetrical, and no unmelted solder is produced.

Therefore, if the shape and size of the solder preform 103 satisfy both the conditions 1 and 2, the optical fiber 101 can be fixed to the fiber mount 102 while suppressing the occurrence of position errors.

(Application example)
Hereinafter, a semiconductor laser module as an application target of the optical fiber fixing method according to the present embodiment will be described with reference to FIG.

FIG. 7 is a perspective view showing the whole image of the semiconductor laser module 1. The semiconductor laser module 1 is a laser module attached to the end of the optical fiber 101, and includes a substrate 10, a CoS (Chip on Submount) 30, a fiber mount 102, and a case 50, as shown in FIG. In FIG. 7, in order to clarify the internal structure of the semiconductor laser module 1, a part of the top plate and the side plate of the case 50 is omitted.

As shown in FIG. 7, the optical fiber 101 is fixed to the upper surface of the fiber mount 102 by solder 103 'using the optical fiber fixing method according to this embodiment. As shown in FIG. 7, the optical fiber 101 is drawn into the semiconductor laser module 1 through an insertion pipe 51 formed in the case 50.

The optical fiber 101 is arranged so that the tip 101a processed into a wedge shape faces the end surface 33a of the semiconductor laser chip 33. Laser light emitted from the end face 33 a of the semiconductor chip 33 enters the optical fiber 101 from the tip 101 a and propagates through the optical fiber 101.

The substrate 10 is a bottom plate of the semiconductor laser module 1. In this application example, as the substrate 10, a plate-like member having a rectangular main surface is used. The substrate 10 functions as a heat sink for dissipating heat generated inside the semiconductor laser module 1 (particularly CoS 30) to the outside of the semiconductor laser module 1. For this reason, the substrate 10 is formed of a material having high thermal conductivity, for example, Cu (copper).

As shown in FIG. 7, the CoS 30 and the fiber mount 102 are placed on the upper surface of the substrate 10. On the upper surface of the substrate 10, the fiber mount 102 is arranged on the side from which the optical fiber 101 is drawn, and the CoS 30 is arranged on the side opposite to the side from which the optical fiber 101 is drawn.

CoS 30 is obtained by integrating a laser mount 31 and a semiconductor laser chip 33.

The laser mount 31 is a support that supports the semiconductor laser chip 31. In the present embodiment, as shown in FIG. 7, a plate-shaped member having a rectangular main surface is used as the laser mount 31, and the lower surface of the laser mount 31 is parallel to the upper surface of the substrate 10, and The long side of the main surface is arranged so as to be parallel to the long side of the main surface of the submount 20. The laser mount 31 is bonded to the upper surface of the substrate 10 by solder 62 that spreads between the lower surface of the laser mount 31 and the upper surface of the substrate 10.

As shown in FIG. 7, a semiconductor laser chip 30 is placed on the upper surface of the laser mount 31. The semiconductor laser chip 33 is a laser light source that emits laser light from its end face 33. In the present embodiment, a high-power semiconductor laser mainly made of GaAs (gallium arsenide) and having a cavity length of 3 mm or more is used. As shown in FIG. 7, the semiconductor laser chip 33 is arranged so that its extending direction is parallel to the long side of the main surface of the laser mount 31, and is attached to the laser mount 31 via a CuW (copper tungsten) layer 32. It is joined. Further, as shown in FIG. 7, the semiconductor laser chip 33 is connected to a circuit formed on the upper surface of the laser mount 31 via a wire 34, and is driven by a current supplied from this circuit.

(Modification)
Hereinafter, modified examples of the present embodiment will be described with reference to FIGS. 8A to 8C and FIGS. 9A to 9E.

In this modification, step S103 described above is replaced with the following step S203.

(Step S203)
While applying a load toward the fiber mound 102 to the solder preform 103, the laser irradiation region 102b on the surface of the fiber mount 102 is irradiated with the laser beam 300, and the laser beam 300 is irradiated, so that the temperature rises. The solder preform 103 is melted by heat conduction from the laser irradiation region 102b.

FIGS. 8A to 8C are diagrams showing a procedure of a process example in which a load is applied toward the fiber mound 102 with respect to the solder preform 103. FIG. In this process example, a solder guide 201 is used as shown in FIG. The solder guide 201 is a jig used for placing the solder preform 103 on the upper surface of the fiber mount 102 and applying a load to the upper surface of the placed solder preform 103. It is comprised from the support part 201b. A guide hole through which the solder preform 103 can pass is formed in the guide portion 201a.

First, as shown in FIG. 8A, the guide part 201 a is fixed to the fiber mount 102 by fitting the support part 201 a into a part of the case 50.

Subsequently, as shown in FIG. 8B, the solder preform 103 is dropped into the guide hole of the guide portion 201 a, and the solder preform 103 is placed at a predetermined position on the metallized region of the fiber mount 102.

Subsequently, as shown in FIG. 8C, a solder push rod 202 is inserted into the guide hole of the guide portion 201 a, and the load directed to the fiber mount 102 on the upper surface of the solder preform 103 through the solder push rod 202. Is applied.

Although not shown in the figure, the case 50 is set on the aligning device with the load applied to the fiber mount 102 applied to the upper surface of the solder preform 103, and after aligning, the laser irradiation area 102b The laser 300 is irradiated. As a result, the solder preform 103 is melted and re-solidified, whereby the optical fiber 101 is fixed to the upper surface of the fiber mount 102.

FIGS. 9A to 9E show how the solder preform melts and re-solidifies as time elapses after the laser irradiation region 102b on the surface of the fiber mount 102 is irradiated in step S203. FIG.

As shown in FIG. 9A, when the laser irradiation region 102b is irradiated with the laser beam 300, the temperature below the solder preform 103 exceeds the melting point due to heat conduction from the laser irradiation region 102b. As shown in b), the solder preform 103 starts to melt from the lower part. The melted lower part begins to spread along the upper surface of the metallized layer 102a. In the present modification, since the load toward the fiber mount 102 is applied to the solder preform 103, the solder preform 103 is pushed out toward the fiber mount 102. The temperature of the upper part of the extruded solder preform 103 exceeds the melting point due to heat conduction, and the upper part changes into a spherical shape due to the influence of surface tension as shown in FIG. Fall towards the. In this way, the entire solder preform 103 is melted. The melted solder starts to be deformed into a substantially hemispherical shape to minimize its surface area due to the influence of surface tension, and starts to envelop the optical fiber 101 as shown in FIG. Thereafter, as shown in FIG. 9E, the solder that wraps around the optical fiber 101 and becomes substantially hemispherical is solidified again when the heating by the laser beam 300 is finished and the temperature of the fiber mount 102 falls below the solder melting point. . Thereby, the optical fiber 101 is fixed on the fiber mount 102.

9A to 9E exemplify a structure in which the lower end of the solder push rod 202 does not reach the upper surface of the fiber mount 102 and stops halfway, this is not intended to limit the present embodiment. . For example, the lower end of the solder push rod 202 may once reach the upper surface of the fiber mount 102, the solder push rod 202 may be pulled upward when the solder is in a molten state, and then the laser 300 may be stopped to resolidify the solder. .

In this modification, the solder preform 103 to which a load is applied is pushed out toward the fiber mount 102, so that it is difficult for the solder preform 103 to remain undissolved as compared to the case where no load is applied.

In addition, since the solder preform 103 to which a load is applied is pushed out toward the fiber mount 102, the internal flow and the surface flow generated in the solder after melting have a large flow velocity. For this reason, it is more difficult to form an oxide film on the surface of the solder than when no load is applied. Moreover, even if an oxide film is formed, the oxide film is broken by the flow that rises from the inside. As described above, in the present modification, the solder 103 ′ after solidification is present in the extension of the optical fiber 101 as compared with the case where no load is applied because it is not easily affected by the oxide film that can be formed on the surface of the molten solder. Problems such as left-right asymmetry with respect to direction are less likely to occur.

As described above, in this modified example, even when the shape and size of the solder preform 103 does not satisfy at least one of the above (Condition 1) and (Condition 2), The shape of the solder is left-right symmetric, and there is no unmelted solder.

For this reason, in this modification, even if the shape and size of the solder preform 103 do not satisfy at least one of the above (Condition 1) and (Condition 2), the optical fiber 101 It can be fixed to the mount 102 while suppressing the occurrence of position errors.

As described above, the optical fiber fixing method according to the present invention is an optical fiber fixing method for fixing an optical fiber to a support member, and holds the optical fiber along the upper surface of the support member. A placing step of placing a solder preform made of fluxless solder on the upper surface of the support member; and irradiating a laser beam onto a laser beam irradiation region set on the surface of the support member; A melting step of melting the solder preform by heat conduction from the irradiation region, and the solder preform placed in the placing step is formed of the optical fiber held in the holding step. The distance between the surface of the optical fiber held at the holding step and the upper surface of the support member is H, and the diameter of the optical fiber is D. , When the height of the solder preform is placed at the top the placing step is L, and satisfies the H + D <L, it is characterized in that.

Further, in the optical fiber fixing method according to the present invention, the value obtained by dividing the surface area of the solder preform by the volume of the solder preform is less than 16.5 with the reciprocal of millimeter as a unit. preferable.

According to the above optical fiber fixing method, since the surface area is smaller than the volume of the solder preform, the influence of the oxide film formed on the surface of the molten solder in the melting step is suppressed, and the solidified solder The shape is symmetrical with respect to the extending direction of the optical fiber. For this reason, the optical fiber can be fixed to the support member with high positional accuracy.

In the optical fiber fixing method according to the present invention, the value obtained by dividing the contact area where the solder preform and the supporting member are in contact with each other by the height of the solder preform is 0 in millimeters. Greater than .05.

According to the above optical fiber fixing method, the contact area between the solder preform and the support member is larger than the height of the solder preform. The solder preform can be sufficiently melted by heat conduction from the irradiation region. For this reason, the unmelted solder preform does not occur, and the optical fiber can be fixed to the support member with high positional accuracy.

In the optical fiber fixing method according to the present invention, it is preferable that the melting step melts the solder preform while applying a load toward the support member with respect to the solder preform.

According to the above optical fiber fixing method, the internal flow and the surface flow generated in the solder after melting have a large flow velocity by melting the solder preform while applying a load to the solder preform. For this reason, compared with the case where a load is not applied, an oxide film is hard to be formed on the surface of the molten solder. Moreover, even if an oxide film is formed, the oxide film is broken by the flow that rises from the inside. Thus, according to the above optical fiber fixing method, the influence of the oxide film that can be formed on the surface of the molten solder is further suppressed, and the optical fiber is fixed to the support member with high positional accuracy. Can do.

In the optical fiber fixing method according to the present invention, it is preferable that the laser light irradiation region is set on the upper surface of the support member on the side opposite to the optical fiber as viewed from the solder preform. .

According to the above optical fiber fixing method, the optical fiber is mistakenly irradiated with the laser light as compared with the case where the laser light irradiation region is set on the same side as the optical fiber when viewed from the solder preform. The risk of damaging the solder preform can be reduced, and the heat generated by the laser beam can be effectively used to melt the solder preform.

The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

The present invention can be suitably applied to fix an optical fiber to a fiber mount. Moreover, it can apply suitably for the fixing process of the optical fiber at the time of manufacturing a semiconductor laser module.

DESCRIPTION OF SYMBOLS 1 Semiconductor laser module 101 Optical fiber 101a Metallized layer 102 Fiber mount (support member)
102a Metallized layer 102b Laser light irradiation region 103 Solder preform

Claims

An optical fiber fixing method for fixing an optical fiber to a support member,
Holding the optical fiber along the upper surface of the support member;
A mounting step of mounting a solder preform made of fluxless solder on the upper surface of the support member;
Irradiating a laser beam irradiation region set on the surface of the support member with a laser beam, and melting the solder preform by heat conduction from the laser beam irradiation region,
The solder preform placed in the placing step is located on one side of the optical fiber held in the holding step,
The distance between the surface of the optical fiber held in the holding step and the upper surface of the support member is H, the diameter of the optical fiber is D, and the solder preform placed in the placing step is When the height is L, H + D <L is satisfied.
An optical fiber fixing method.
The value obtained by dividing the surface area of the solder preform by the volume of the solder preform is less than 16.5 in units of the reciprocal of millimeters.
The optical fiber fixing method according to claim 1.
The value obtained by dividing the contact area where the solder preform and the support member are in contact with each other by the height of the solder preform is greater than 0.05 in millimeters.
The optical fiber fixing method according to claim 1, wherein the optical fiber is fixed.
The melting step melts the solder preform while applying a load toward the support member with respect to the solder preform.
The optical fiber fixing method according to any one of claims 1 to 3, wherein:
The laser light irradiation region is set on the upper surface of the support member on the side opposite to the optical fiber as viewed from the solder preform.
The optical fiber fixing method according to any one of claims 1 to 4, wherein the optical fiber is fixed.
A manufacturing method for manufacturing a laser module comprising an optical fiber and a support member for supporting the optical fiber,
Using the optical fiber fixing method according to any one of claims 1 to 5, the optical fiber and the support member are fixed.
The manufacturing method characterized by the above-mentioned.