JP2002341194A - Semiconductor laser module and method for manufacturing semiconductor laser module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor laser module which can stably realize highly efficient coupling. SOLUTION: A semiconductor laser element 62 is placed on a carrier 58 in a module package 55, and light emitted therefrom is made incident on an optical fiber 64. A ferrule 65 housing the optical fiber 64 is fixed on the carrier 58 by a front ferrule holder 66 and a rear ferrule holder 67. The ferrule 65 is YAG-welded to the front ferrule holder 66 in the state of optically positioning the optical fiber 64. Positional deviation in the Y axial direction after welding of the front ferrule holder 66 (vertical direction in Figure) can be corrected by the screwing quantity of a screw 68 placed at the rear ferrule holder 67 into a screw hole (not shown in figure) provided at the end of the ferrule 65.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser module, and more particularly to a semiconductor laser module capable of accurately positioning an optical fiber with respect to a semiconductor laser element.

[0002]

2. Description of the Related Art In a semiconductor laser module, a semiconductor laser element is maintained at a desired temperature, and a laser beam outputted from the semiconductor laser module is optically coupled to an optical fiber.

Meanwhile, a semiconductor laser device that outputs light in the 980 nm band has a radiation pattern of 20 to 40 degrees with respect to a vertical radiation angle, whereas a horizontal radiation angle of 5 to 40 degrees.
It is 15 degrees and has an elliptical shape. Therefore, when coupled with an optical fiber whose mode field diameter is close to a perfect circle,
Excessive loss occurs.

[0004] In order to solve such a problem, a method of placing a cylindrical lens between a semiconductor laser element and an optical fiber has conventionally been adopted. This is a technique in which a beam output from a semiconductor laser element is made close to a circle by condensing light only in the vertical direction with a cylindrical lens. However, when this method is employed, there is no light condensing action in the horizontal direction, so that the coupling efficiency between the semiconductor laser device and the optical fiber cannot be improved.

Of course, it has also been proposed to make the shape of the beam shaping lens or the fiber itself elliptical. However, in the former case, there is a problem that the configuration of the device is complicated. In the latter case, there is a problem that the processing of the fiber is not easy.

FIG. 4 shows the shape of the end of an optical fiber proposed to solve the above problem. JP-A-63-89272 or JP-A-8-89272.
In this proposal disclosed in Japanese Patent No. 271763, the end of the optical fiber 11 is processed into a tapered shape or a wedge shape. Line-shaped part 1 where two cut surfaces 12 and 13 intersect
4 is parallel to the X axis. In the case of the proposed optical fiber 11, the processing of the wedge-shaped portion can be easily performed by using an existing technique such as polishing. Further, since there is no need to dispose an optical lens, it is possible to dispose the semiconductor laser element and the optical fiber closer to each other.
As a result, it is not necessary to particularly consider that light does not converge in the horizontal direction (the X-axis direction in FIG. 4).

In the configuration of the semiconductor laser module shown in FIG. 4, the semiconductor laser element and the optical fiber are directly connected. For this reason, there is a problem that tolerance of adjustment of the positional relationship between the two is strict. For this reason, if optical positioning is performed between the semiconductor laser element and the optical fiber to fix these positional relations by YAG welding, a positional shift actually occurs due to the influence of temperature or the like.

Therefore, it has been proposed to fix one end of the ferrule to which the optical fiber is attached, on the side of the semiconductor laser element, by welding first, and to correct the displacement generated at the time of fixing at the other end of the ferrule. According to this proposal, even if a slight displacement occurs in the Y-axis direction shown in FIG. 4 due to the fixation of one end of the ferrule, the position of the one end is moved by moving the position of the other end of the ferrule in the Y-axis direction. Is corrected. After the position is completely corrected, the other end of the ferrule is similarly subjected to YAG welding.

[0009]

However, even if the ferrule is positioned in two stages and fixed by YAG welding as described above, the ferrule is positioned at the other end of the ferrule for the same reason that an error occurs during the first YAG welding. 2
It is inevitable that an error occurs during the second YAG welding. Of course, this error tends to be smaller than the error that occurs when one end of the ferrule is fixed,
The occurrence of the error adversely affects the optical coupling between the semiconductor laser element and the optical fiber, and causes a problem of lowering the coupling efficiency.

FIG. 5 shows another proposal for improving the optical coupling between a semiconductor laser and an optical fiber. In this proposal shown in Japanese Patent Application Laid-Open No. H2-211411, the substrate 41 is formed so that its cross section becomes U-shaped.
The semiconductor laser 42 is mounted on the upper part of the vertical wall 41A side, and the optical fiber 43 is fixed on the upper horizontal plate 41B of the substrate 41. Then, by screwing a screw 44 from the lower horizontal plate 41C of the substrate 41 and adjusting the amount by which the upper horizontal plate 41B is lifted at the tip thereof, the coupling between the semiconductor laser 42 and the optical fiber 43 is adjusted.

However, in this proposal, since the substrate 41 is processed into a special shape and the screws 44 are directly attached to the substrate 41, not only is the assembly and adjustment of the semiconductor laser module complicated, but also because of the stress applied to the substrate 41. However, there is a problem that the reliability of the semiconductor laser module itself is reduced.

An object of the present invention is to provide a semiconductor laser module capable of stably achieving high-efficiency coupling.

[0013]

According to the present invention, (a) a semiconductor laser, (b) a carrier on which the semiconductor laser is arranged, and (c) laser light emitted from the semiconductor laser are incident. An optical fiber, and (d) a ferrule which is a cylindrical member for fixing the optical fiber on the carrier and has a screw hole provided in a predetermined position on a side opposite to the end where the semiconductor laser is located in a direction perpendicular to the carrier. E) a front ferrule holder which is disposed on the carrier and fixes an end of the ferrule located on the semiconductor laser side;
The semiconductor laser module is provided with a rear ferrule holder disposed on the carrier and having a screw screwed with the screw hole.

According to the first aspect of the present invention, the end of the ferrule located on the semiconductor laser side is fixed by the front ferrule holder, and the ferrule is disposed at a predetermined position opposite to the end where the semiconductor laser is located. By screwing the screw of the rear ferrule holder into the screw hole, it is possible to correct the positional deviation that remains after fixing with the front ferrule holder or that occurs when fixing, by adjusting the screw.

According to the second aspect of the present invention, (a) a semiconductor laser, (b) a carrier in which the semiconductor laser is disposed via a heat sink, and (c) a tip portion forms an edge parallel to the carrier. An optical fiber that is cut into a wedge shape, and that receives laser light emitted from a semiconductor laser from the tip of the wedge shape; and (d) a cylindrical member that fixes the optical fiber on a carrier. A ferrule having a screw hole perpendicular to the carrier at a predetermined position opposite to the end where the semiconductor laser is located; and (e) a front disposed on the carrier and fixing the end of the ferrule located on the semiconductor laser side. A ferrule holder,
(F) The semiconductor laser module is provided with a rear ferrule holder, which is disposed on the carrier and has a screw screwed thereto and fitted with a screw.

That is, in the second aspect of the present invention, an optical fiber is used which is cut into a wedge shape so that the tip portion forms an edge parallel to the carrier. Then, the end of the ferrule located on the semiconductor laser side is fixed with a front ferrule holder, and the screw of the rear ferrule holder is inserted into a screw hole located at a predetermined position on the opposite side to the end of the ferrule where the semiconductor laser is located. By screwing, it is possible to correct a position shift remaining after fixing with the front ferrule holder or occurring at the time of fixing by adjusting the screw.

According to a third aspect of the present invention, in the semiconductor laser module according to the first aspect, a lens is disposed at an end of the optical fiber.

That is, in the third aspect of the present invention, unlike the second aspect of the present invention, the present invention is applied to an optical fiber in which a lens is disposed at the tip end. The lens may be a cylindrical lens. Also, the lens need not necessarily be attached to the tip of the optical fiber. What is necessary is just to arrange | position between a semiconductor laser and an optical fiber.

According to a fourth aspect of the present invention, in the semiconductor laser module according to the first or second aspect, the screw hole is formed near the end of the ferrule in a direction perpendicular to the carrier.

That is, if the screw hole is disposed near the end of the ferrule, the amount of movement of the tip of the optical fiber relative to the amount of movement of the screw attached to the rear ferrule holder is slight. Therefore, highly accurate correction becomes possible.

According to the fifth aspect of the present invention, (a) an arrangement step of arranging a semiconductor laser element and a photodiode on a carrier; and (b) a tip of an optical fiber attached to a ferrule in relation to the semiconductor laser element. A first adjusting step of positioning and fixing a side of the ferrule close to the semiconductor laser element with a front ferrule holder arranged on the carrier so that the positional relationship is maintained; and (c) the first adjusting step The error component in the vertical direction with respect to the carrier in the position error between the semiconductor laser and the optical fiber existing after fixing the ferrule with the screw is screwed into a screw hole provided on the rear ferrule holder on the far side of the ferrule from the semiconductor laser element. And a second adjusting step of correcting by the amount to be inserted. That.

That is, in positioning the optical fiber when manufacturing the semiconductor laser module, first, the tip of the optical fiber attached to the ferrule is positioned in relation to the semiconductor laser element. The side close to the semiconductor laser element in the ferrule is fixed with a front ferrule holder placed on the carrier so that the relationship is maintained, and the error in the vertical direction with respect to the carrier in the position error between the semiconductor laser and the optical fiber existing after this fixing. The component is corrected by an amount by which a screw arranged in the rear ferrule holder is screwed into a screw hole provided on a side of the ferrule remote from the semiconductor laser element. In the second adjustment step, the displacement is corrected by using the screw, so that there is no problem that an error occurs when the temperature returns to the normal temperature as in the case of welding.

According to a sixth aspect of the present invention, in the method of manufacturing a semiconductor laser module according to the fifth aspect, there is provided a rear ferrule holder fixing step of fixing the rear ferrule holder on a carrier. It is characterized in that the processing in the second adjustment step is performed later in time.

That is, in the invention according to the sixth aspect, the processing in the second adjusting step is performed in time after the rear ferrule holder fixing step, so that the displacement when the rear ferrule holder is fixed on the carrier can be reduced. It can be corrected by adjusting the screw.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiments.

FIG. 1 shows a main part of a semiconductor laser module according to an embodiment of the present invention. The semiconductor laser module 51 includes a module package 55 in which a hollow module package main body 53 and a cover 54 covering the upper part thereof are arranged on a bottom plate 52. Inside the module package 55, an electronic cooler 57 represented by a Peltier element is arranged on the bottom plate 52, and a carrier 58 is arranged thereon. On the carrier 58, a monitoring photodiode 59, 9
A heat sink 63 having an 80 nm band semiconductor laser element 62 disposed on its upper surface, and a front ferrule holder 66 and a rear ferrule holder 67 for fixing a ferrule 65 to which the tip of an optical fiber 64 is attached are fixed. Ferrule 6 in rear ferrule holder 67
A screw 68 which is screwed into a screw hole provided at a predetermined position of No. 5 is attached. The gap between the module package 55 and the optical fiber 64 is filled with low melting point solder or the like and hermetically sealed.

FIG. 2 shows how the ferrule is attached by the front ferrule holder. The front ferrule holder 66 is mounted on the carrier 58, and the tip of the ferrule 65 is sandwiched between a pair of columnar portions 66A and 66B. As shown in FIG. 4, the end of the optical fiber 64 is processed into a wedge shape, and the line-shaped portion 14 where the two cut surfaces 12 and 13 intersect is parallel to the X axis. The incident light is condensed and optically coupled to the optical fiber 64 by the wedge-shaped tip. The operator attaches the tip of the ferrule 65 to the pair of columnar portions 66A, 66A.
The position of the front ferrule holder 66 is adjusted at the optimum position while the ferrule 65 is held at the optimum position, and the ferrule 65 is fixed to the pair of columnar portions 66A and 66B of the front ferrule holder 66 by YAG welding.

FIG. 3 shows the relationship between the amount of axial deviation between the semiconductor laser element and the optical fiber and the additional loss in this semiconductor laser module. This figure shows X,
The figure shows an allowable error curve (tolerance curve) representing the amount of reduction in coupling efficiency when the optical fiber 64 is displaced in each of the Y and Z axial directions. In the figure, a curve 71 represents the characteristic with respect to the X axis, and a curve 72 represents the characteristic with respect to the Y axis. Curve 73 represents the characteristic for the Z axis. As can be seen from the figure, in the case of the Y axis,
For a displacement of about 0.5 μm, a large additional loss of 3 dB or more occurs. On the other hand, in the case of the X axis and the Z axis, it is 0.5 dB or less.

Since the tolerance for the Y-axis is stricter than the X-axis and the Z-axis as described above, when the fixing of the front ferrule holder 66 is completed, the operator uses the rear ferrule holder 67 to turn the Y-axis. The readjustment is performed only for the positional deviation in the direction. As shown in FIG. 1, the distance from the front end position of the ferrule 65 facing the semiconductor laser element 62 to the fixed position of the front ferrule holder 66 is “1”, and from this position to the screw hole of the rear ferrule holder 67 in the ferrule 65. Distance of “L”
And Then, the displacement x in the X-axis direction is increased to L / l on the rear ferrule holder 67 side. For example, the numerical value l
Is 1 (mm) and the numerical value L is 10 mm, the tolerance is relaxed ten times. Therefore,
By rotating the screw 68 clockwise or counterclockwise, fine adjustment of the displacement in the Y-axis direction becomes possible.

As described above, conventionally, the ferrule 65 and the ferrule holder are fixed by YAG welding also on the rear ferrule holder 67 side. For this reason,
At the time of the second welding and fixing, the fiber is again shifted in position. In this embodiment, the rear end of the ferrule 65 is not fixed only by welding,
To be able to move up and down, and to perform welding in this state if necessary. Therefore, even if a misalignment occurs between the semiconductor laser element 62 and the tip of the optical fiber 64 when the front ferrule holder 66 is fixed by welding, the misalignment can be corrected on the submicron order by adjusting the screw 68. .

Next, a brief description will be given of a method of manufacturing the semiconductor laser module of the present embodiment described above. First, the semiconductor laser element 62 fixed on a heat sink (not shown)
An optical component in which the photodiode 59 and the photodiode 59 are arranged on the carrier 58 shown in FIG. 1 is prepared and fixed on the electronic cooler 57. Next, the optical fiber 6 is attached to the module package body 53.
The semiconductor laser device 62 and the optical fiber 64 are aligned on the carrier 58. At the optimum position, the ferrule 65 is fixed to the front ferrule holder 66 by YAG welding. The front ferrule holder 66 is provided with a carrier 58.
YAG is similarly fixed on the top. Either of these YAG fixings may be performed first.

Front ferrule holder 66 and ferrule 6
When fixing 5, the laser light for YAG welding is applied from above semiconductor laser module 51. For this reason, YA
When the welded portion is solidified by the G laser, a pulling force is generated in the Y-axis direction, thereby causing a displacement in this direction. With respect to the X-axis direction, the laser beam is radiated at symmetrical positions, so that the force in this direction is offset. Z
Since no force is applied in the axial direction, the axial displacement in this direction is negligible. If a positional shift in the Y-axis direction is confirmed, the position of the ferrule 65 is adjusted on the rear end side far from the semiconductor laser element 62.

Before the first adjustment by the front ferrule holder 66 is performed, the tip of the screw 68 attached to the rear ferrule holder 67 is screwed into a screw hole of the ferrule 65 by a predetermined amount. The position of the rear ferrule holder 67 in the X-axis direction and the Z-axis direction is first corrected, and the rear ferrule holder 67 is fixed on the carrier 58. When correcting these two axes,
If the ferrule 65 is fixed in the clamped state when the ferrule 65 is fixed to the front ferrule holder 66, no displacement occurs in the X-axis and Z-axis directions.

Thus, the rear ferrule holder 67
Is fixed on the carrier 58, the clamp (not shown) is removed, the output of the semiconductor laser module 51 is measured while rotating the screw 68, and adjustment in the Y-axis direction is performed so that the tip of the ferrule 65 is at the optimum position. In this correction work, the YA between the front ferrule holder 66 and the ferrule 65 is
A force is applied in a predetermined rotation direction with the G welding point as a fulcrum,
The displacement of the tip of the ferrule 65 is corrected. At this time, even if the rear end of the ferrule 65 is relatively largely moved in the Y-axis direction by the screw 68, the corresponding movement of the front end is very small. Therefore, the displacement in the Y-axis direction can be corrected with high accuracy. When the correction of the displacement is completed in this way, the rear ferrule holder 67 is fixed to the ferrule 65 by YAG welding. At this time, the ferrule 65 is screwed by the screw 68 to the rear ferrule holder 6.
7 so that movement in the Y-axis direction can be performed only by the screw 68. Therefore, the YAG welding can be performed without causing a displacement in the Y-axis direction.

In the embodiment, the positioning of the optical fiber 64 having a wedge-shaped tip has been described. However, a semiconductor laser module using an optical fiber having a lens disposed at the tip or an optical fiber 64 and a semiconductor laser element 62 are described.
Naturally, the present invention can be similarly applied to a semiconductor laser module in which a lens is disposed between the two.

[0037]

As described above, claims 1 to 6 are described.
According to the invention described above, the ferrule is fixed on the carrier with the front ferrule holder on the side closer to the semiconductor laser and the rear ferrule holder on the far side, and a screw is attached to the rear ferrule holder on the far side to finely adjust the ferrule. Since the adjustment is performed, it is possible to perform a correction that is not affected by welding. In addition, since the adjustment is performed behind the ferrule, the adjustment can be performed with a smaller moving amount than the moving amount of the screw, and a highly accurate adjustment can be performed.

According to the second aspect of the present invention, since an optical fiber cut into a wedge shape so that the tip forms an edge parallel to the carrier is used, it is necessary to prepare a special lens. In addition, the semiconductor laser module can be downsized and the assembly can be simplified.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a main part of a semiconductor laser module according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating how a ferrule is attached by a front ferrule holder in the present embodiment.

FIG. 3 is a characteristic diagram showing a relationship between an amount of axial deviation between a semiconductor laser element and an optical fiber in a semiconductor laser module and an additional loss;

FIG. 4 is a perspective view showing the shape of an end portion of a conventionally proposed optical fiber.

FIG. 5 is a sectional view of a principal part of another conventionally proposed semiconductor laser module.

[Explanation of symbols]

 12, 13 Cutting surface 14 Line-shaped portion 51 Semiconductor laser module 55 Module package 58 Carrier 59 Photodiode 62 Semiconductor laser element 64 Optical fiber 65 Ferrule 66 Front ferrule holder 67 Rear ferrule holder 68 Screw

Claims (6)

[Claims] 1. A semiconductor laser, a carrier on which the semiconductor laser is arranged, an optical fiber for receiving laser light emitted from the semiconductor laser, and a cylindrical member for fixing the optical fiber on the carrier. A ferrule provided with a screw hole in a direction perpendicular to the carrier at a predetermined position opposite to the end where the semiconductor laser is located; and a front arranged on the carrier and fixing an end of the ferrule located on the semiconductor laser side. A semiconductor laser module comprising: a ferrule holder; and a rear ferrule holder that is disposed on the carrier and has a screw that is screwed into the screw hole. 2. A semiconductor laser, a carrier in which the semiconductor laser is disposed via a heat sink, and a tip portion cut into a wedge shape so as to form an edge parallel to the carrier. An optical fiber for emitting the emitted laser light from the tip of the wedge; and a cylindrical member for fixing the optical fiber on the carrier, and a carrier at a predetermined position opposite to the end where the semiconductor laser is located. A ferrule provided with a screw hole in the vertical direction, a front ferrule holder arranged on the carrier and fixing an end of the ferrule located on the side of the semiconductor laser, A rear ferrule holder to which a screw for fitting is attached. 3. The semiconductor laser module according to claim 1, wherein a lens is disposed at a tip of said optical fiber. 4. The semiconductor laser module according to claim 1, wherein said screw hole is threaded in a direction perpendicular to said carrier near an end of said ferrule. 5. An arranging step of arranging a semiconductor laser element and a photodiode on a carrier; and positioning an end of an optical fiber attached to a ferrule in relation to the semiconductor laser element so that the positional relation is maintained. A first adjusting step of fixing a side of the ferrule close to the semiconductor laser element with a front ferrule holder arranged on the carrier; and the semiconductor laser existing after fixing the ferrule in the first adjusting step. A second component that corrects an error component of the position error of the optical fiber in a direction perpendicular to the carrier by an amount of screwing a screw arranged in a rear ferrule holder into a screw hole provided on a side of the ferrule far from the semiconductor laser element. Manufacturing of a semiconductor laser module, comprising the steps of: Law. 6. A rear ferrule holder fixing step of fixing the rear ferrule holder on a carrier,
6. The method according to claim 5, wherein the processing in the second adjusting step is performed at a time later than the rear ferrule holder fixing step.