JPH02161406A - Semiconductor laser and optical fiber coupler - Google Patents

Abstract

PURPOSE:To substantially prevent positional deviation and to prevent the increase in the coupling loss of a semiconductor laser and an optical fiber by joining a semiconductor laser mount fixed with a semiconductor laser chip and a fiber supporting body fixed with the front end of the optical fiber and positioning the front end of the optical fiber to the semiconductor laser chip. CONSTITUTION:The semiconductor laser mount 1 fixed with the semiconductor laser chip 5 and the optical fiber supporting body 12 fixed with the front end of the optical fiber 10 are joined. The front end of the optical fiber 10 and the semiconductor laser chip 5 are positioned by the joining. The positional deviation is substantially prevented in this way and the increase in the coupling loss of the semiconductor laser and the optical fiber is prevented. Since the semiconductor laser module is miniaturized, the packaging time for assembling is shortened and the cost is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application (I)> The present invention relates to a device for optically coupling a semiconductor laser and an optical fiber.

<Background Art> With the progress in the fields of optical communication, optical recording, etc., optical components and devices using semiconductor lasers as light sources have come to be provided. In these optical components and devices, it is necessary to connect the semiconductor laser and the optical fiber so that there is no loss of optical power from the semiconductor laser. For this reason, the semiconductor laser and the optical fiber have been connected through a lens. but,
When connecting through a lens, the semiconductor laser/optical fiber coupling device has the disadvantage of becoming large. In order to solve this problem, it has been proposed to use an optical fiber whose tip is processed with a ball lens instead of a lens (Utility Model Application No. 143111/1983, Japanese Patent Application Laid-open No. 193113/1983). A conventional semiconductor laser/optical fiber coupling device using an optical fiber will be explained with reference to FIG. FIG. 3 shows a perspective view of this coupling device.

A semiconductor laser mount 2 and a fiber support stand 3 as a fiber support are provided at positions facing each other on the submount substrate 1, and a semiconductor laser chip 5 is fixed to the semiconductor laser mount 2 via a heat sink 4 for heat dissipation. ing. A through hole 6 passing through the fiber support 3 is provided at a position facing the semiconductor laser chip 5 on the fiber support 3.
is formed, and the central axis of the through hole 6 is set to coincide with the light emitting part of the semiconductor laser. An introduction hole 7 is formed in the fiber support stand 3 in a direction substantially perpendicular to the central axis of the through hole 6, and the introduction hole 7 penetrates into the through hole 6 from the upper surface of the fiber support stand 3. The end of the introduction hole 7 on the upper surface of the fiber support base 3 is chamfered to form a chamfered portion 8 . Through hole 6. The introduction hole 7 and the chamfered portion 8 are filled with a low melting point metal such as solder 9, and an optical fiber 10 is fixed to the through hole 6 by passing through the solder 9 approximately at the center thereof. The position of the optical fiber 10 relative to the light emitting part of the semiconductor laser provides the maximum coupling efficiency with the semiconductor laser. It has been adjusted as follows.

The assembly procedure of the above-mentioned semiconductor laser/optical fiber coupling device will be explained.

A spherical solder ball weighed in a predetermined amount is inserted into the chamfered part 8 at the upper part of the introduction hole 7 with the spherical surface touching the slope of the chamfered part 8.
I'll put it on. The optical fiber 10 is inserted into the through hole 6 at a substantially central position and held there, and then the semiconductor laser chip 5 is caused to emit light to align the optical fiber 10 with respect to the emitted light. Adjust and hold 10. With the optical fiber 10 held at the maximum efficiency position, Y A G (Y2A120.,
) The molten solder is irradiated with laser light, flows into the through hole 6 from the introduction hole 7, and solidified after irradiation with the laser light.

In the above-described semiconductor laser/optical fiber coupling device, since the solder balls are uniformly weighed, the solder is evenly distributed around the optical fiber 10, and it is possible to perform highly accurate fixing with little positional deviation. Furthermore, since the optical fiber 10 is aligned before being filled with the solder 9, there is no temperature change in the semiconductor laser chip 5 due to heating, the amount of light emitted is constant, and it is possible to accurately position the optical fiber 10 at the maximum efficiency position. It is possible.

In addition, since heating by mechanical contact is not required when melting the solder balls, the fiber support 3 and the optical fiber 1
No external mechanical force is applied to 0, and no positional deviation occurs.

<Problems to be Solved by the Invention> However, the conventional semiconductor laser/optical fiber coupling device has the following problems.

That is, (2) the optical fiber 10 whose tip is processed into a ball lens has severe alignment tolerance in the X and Y plane directions perpendicular to the optical axis, so even a slight positional deviation will increase the coupling loss. Therefore, as shown in FIG. 3, when the optical fiber 10 is fixed in the middle, a large positional shift occurs in the X and Y directions at the light emitting part of the semiconductor laser using the fixed point as a fulcrum. ■Solder 9 is used to fix the optical fiber 10, but the solder 9 tends to undergo plastic deformation when a certain stress is applied due to the creep phenomenon, so the position of the optical fiber may shift during long-term use. This causes misalignment with the semiconductor laser and increases coupling loss, making it unreliable as a semiconductor laser/optical fiber coupling device. ■Handa 9
When used to fix the optical fiber 10, the solder 9 contracts when it hardens, causing positional displacement mainly in the X and Y directions and increasing coupling loss.

Furthermore, when the solder 9 is used, not only the fiber support 3 is heated but also the semiconductor laser chip 5 is exposed to high temperature, and the heat sink 4 and the semiconductor laser tube 5 may melt, which poses a risk of shortening the life of the semiconductor laser.

The present invention has been made in view of the above situation, and an object of the present invention is to provide a semiconductor laser/optical fiber coupling device that prevents an increase in coupling loss between a semiconductor laser and an optical fiber due to misalignment of the optical fiber. shall be.

Means for Solving the Problems> The configuration of the present invention to achieve the above object is a semiconductor laser/optical fiber coupling device that optically couples a semiconductor laser chip and an optical fiber whose tip is processed into a ball lens. The semiconductor laser chip is fixed to the semiconductor laser mount, the tip of the optical fiber is fixed to a fiber support, the tip of the optical fiber is positioned with respect to the semiconductor laser chip, and the tip of the optical fiber is fixed to the semiconductor laser mount. It is characterized in that the fiber supports are joined.

Function> A semiconductor laser mount to which a semiconductor laser chip is fixed is joined to a fiber support body to which a tip of an optical fiber is fixed, and the tip of the optical fiber is positioned with respect to the semiconductor laser chip. Since the tip of the optical fiber is fixed to the fiber support, it is difficult for the tip of the optical fiber to be misaligned.

Embodiments FIG. 1 is a perspective view of a semiconductor laser/optical fiber coupling device according to an embodiment of the present invention, and FIG. 2 is a cross-sectional side view thereof. In addition, the same parts as in Fig. 3 are given the same symbols!
Repeated explanation will be omitted.

The illustrated semiconductor laser/optical fiber coupling device consists of a semiconductor laser section 11 and a fiber support section 12.

The semiconductor laser section 11 has a general semiconductor laser mount structure in which a heat sink 4 for heat dissipation is soldered onto a semiconductor laser mount 2, and a semiconductor laser chip 5 is further soldered thereon. The light emitting surface is aligned with the end face of the semiconductor laser mount 2. The semiconductor laser mount 2 is made of gold-plated oxygen-free steel in consideration of heat radiation. One of the electrodes is led to the semiconductor laser mount 2 as a ground, and the other electrode is connected to a gold-plated copper plate 14 via a ceramic insulator 13.
are led from the top surface of the semiconductor laser chip 5.

The fiber support section 12 is composed of a fiber support stand 3, a pinhole 15, and a fiber guide 16, as shown in FIG. The optical fiber 10 whose tip is processed into a spherical lens is a single mode fiber having a spherical radius in the range of 5 to 30 μm. The angle of the sphere at the tip of the optical fiber 10 is 30 to 100 degrees in full width, and this angle matches the angle of the pinhole 15 for fixing the tip of the optical fiber 10. The optical fiber 10 has a metal film on its surface in order to be fixed to the fiber guide 16, and it is preferable that the film be produced by sputtering. Further, since the optical fiber 10 can easily form an external cavity with the semiconductor laser, a non-reflection film matching the wavelength of the semiconductor laser is attached to the surface. A gap 17 in the range of 20 to 100 μm is provided between the pinhole 15 and the end face of the fiber support 3 so that the optical axis direction can be observed simply by abutting the fiber support 3 against the semiconductor laser mount 2. It is provided. This gap 17 is effective for avoiding alignment of the centers and bringing the end faces into close contact when the surfaces are brought into contact with each other, and the spherical lens processing portion at the tip of the optical fiber 10 protrudes from the pinhole 15. to fix the tip of the optical fiber 10. That is, the pinhole 15 has a tapered hole that matches the angle of the optical fiber 10 at 5 [(spherical lens processing portion). The fiber guide 16 is press-fitted into the fiber support stand 3, and the fiber guide 1
The material 6 is made of metal or ceramic.

Next, a procedure for assembling the semiconductor laser/optical fiber coupling device having the above configuration will be explained.

The semiconductor laser section 11 has a structure in which a ceramic insulator 13 and a copper plate 16 are already integrally formed on a semiconductor laser mount 2, and a heat stock 4 and a semiconductor laser chip 5 are soldered to the semiconductor laser mount 2. The fiber support section 12 is connected to the fiber support base 3. It is composed of a fiber guide 16 and a pinhole 15, and the optical fiber <10 is fitted into the fiber guide 16 and fixed at the end 18 with solder or adhesive. The optical fiber 10 is automatically adjusted by the pinhole 15 to a position where the coupling efficiency with the semiconductor laser chip 5 is maximized. Therefore, the position of the pinhole 15 in the optical axis direction is determined by setting the width of the gap 17 in advance so as to satisfy the maximum efficiency, and attaching the pinhole 15 to the fiber guide 16 or forming the pinhole 15 in the fiber guide 16. put. The pinhole 15 is preferably formed by drilling with a high-precision drilling machine.

As described above, the semiconductor laser section 11 and the fiber support section 1 are
2 are prepared, and these are aligned and coupled with high precision so that the coupling efficiency is maximized.

The alignment method uses an automatic centering device consisting of an optical fine movement table that can achieve accuracy down to 0.1 μm. That is, a current is passed in the forward direction of the semiconductor laser to cause the laser to oscillate, and the light is guided to the optical fiber 10 with maximum efficiency. At this time, since the optical axis direction of the optical fiber 10 is determined by the width of the gap 17 and the amount of protrusion of the tip of the optical fiber 10 processed with a spherical lens, self-alignment is performed in X, Y
This will align the direction. After the semiconductor laser section 11 and the fiber support section 12 have been aligned, they are joined together. An easy way to do this is to use adhesive or solder. Uses laser welding. The advantage of YAG laser welding is that it can be processed in a short time and welding can be performed without exposing the workpiece to high temperatures. However, in order to minimize positional deviation during irradiation, irradiation is performed from both sides at the same time. As shown in FIGS. 1 and 2, the position of the irradiation is such that the ceramic insulator 1
Those with 3 can only have space to irradiate one or two points. On the other hand, in the opposite direction, many irradiation points can be expected. For the sake of explanation, three-point irradiation will be explained as shown in FIGS. 1 and 2. First, press the fiber support 3 against the semiconductor laser mount 2 after alignment before irradiation. This is very important because it prevents positional deviation from occurring during YAG laser irradiation. YAG laser irradiation is first performed at laser irradiation positions I [19 and 20 at the same time to confirm that it has been securely fixed, and then by irradiating laser irradiation position 1 [21], the aim is to further improve reliability. The experiment used a 50J YAG laser and a voltage of 1200V for 50
Laser light with a pulse width of +ms was divided into two and irradiated. The semiconductor laser mount 2 used in the experiment was made of oxygen-free copper,
The fiber support part 3 is made of stainless steel (SUS 3
03), and each has a different thermal conductivity. In the case of YAG laser welding, materials with low thermal conductivity melt better.
It is desirable to make adjustments in advance so that more power is irradiated to the semiconductor laser mount 2. In addition, since there may be cases where sufficient welding is not performed, flanges are formed at both ends of the semiconductor laser mount 2, and similarly the flanges are processed at the portion of the fiber support section 12 that contacts the semiconductor laser mount 2. The butt between the flanges is performed during alignment, making it possible to weld with a low power laser beam. When laser welding is performed on dissimilar metals with such a low power, cracks in the welded portion due to differences in thermal expansion coefficients are less likely to occur.

Through the above steps, the semiconductor laser section 11 and the fiber support section 12 are coupled and integrated.

Next, another assembly procedure of the semiconductor laser/optical fiber coupling device having the above configuration will be explained. Conventional semiconductor laser modules require a jig to support the optical fiber, and space needs to be prepared within the package, which increases the size of the semiconductor laser module.
This makes it possible to assemble conductor modules.

The difference from the previously described assembly procedure is that the optical fiber 10 is not initially fixed to the end 18 of the fiber guide 14 with adhesive or solder. That is, the optical fiber 10 is inserted into the fiber guide 14 twice.

The first step is to prepare a package that will contain the semiconductor laser and optical fiber coupling device. Then, the integrated semiconductor laser/optical fiber coupling device having a structure without the optical fiber 10 is soldered and fixed within the package. In the next step, the optical fiber 10, the tip of which is to be finally coupled with a ball lens, is inserted from the outside of the package without adjustment and is aligned through a hole through which the optical fiber can pass. At this time, the semiconductor laser oscillates. The fiber is guided by a fiber guide 16, and its tip fits into the pinhole 15 without centering. At this point, re-fix the optical fiber 10 at the end 18 of the fiber guide 16 with adhesive or solder, seal the part of the fiber that comes out of the package with adhesive or solder, and finally close the package with a lid. The whole thing will be kept confidential. In other words, the fiber used in the first step is a dummy fiber used to align the fiber whose tip has been processed into the semiconductor laser, and when the coupling device is fitted and fixed in the package, the real optical fiber 10 is pushed in and fixed. .

Therefore, in the above-described semiconductor laser/optical fiber coupling device, the semiconductor laser section 11 and the fiber support section 12 are joined and integrated, and the optical fiber 1 whose tip is processed into a ball lens.
Since the tip of the 0 is fixed with the pinhole 15, even if heat, vibration, etc. are applied from the outside, positional deviation is very small and reliability is high. Therefore, the positional deviation caused by the arrangement of the optical fiber 10 whose tip is processed into a ball lens and the positional deviation caused by soldering are eliminated. In addition, semiconductor laser modules using semiconductor laser/optical fiber coupling devices have been miniaturized,
Assembling time can be shortened and costs can be reduced.

<Effects of the Invention> The semiconductor laser/optical fiber coupling device of the present invention joins the semiconductor laser mount to which the semiconductor laser chip is fixed and the fiber support to which the tip of the optical fiber is fixed, and by joining the optical fiber. Since the tip and the semiconductor laser chip are positioned, there is no possibility of misalignment.
, an increase in coupling loss between the semiconductor laser and the optical fiber can be prevented. Furthermore, since the semiconductor laser module is miniaturized, assembly and mounting time can be shortened and costs can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a semiconductor laser/optical fiber coupling device according to an embodiment of the present invention, FIG. 2 is a cross-sectional side view thereof, and FIG.
The figure is a perspective view of a conventional semiconductor laser/optical fiber coupling device. In the drawings, 2 is a semiconductor laser mount, 3 is a fiber support, 5 is a semiconductor laser chip, 10 is an optical fiber, 11 is a semiconductor laser section, 12 is a fiber support section, 15 is a pinhole, 16 is a fiber guide, 17 is a This is the gap.

Claims (2)

[Claims] (1) A semiconductor laser/optical fiber coupling device for optically coupling a semiconductor laser chip and an optical fiber whose tip is processed into a ball lens, wherein the semiconductor laser chip is fixed to a semiconductor laser mount, and the optical fiber is fixed to a semiconductor laser mount. A semiconductor laser/optical fiber coupling device, characterized in that the tip of the optical fiber is fixed to a fiber support, the tip of the optical fiber is positioned with respect to the semiconductor laser chip, and the semiconductor laser mount and the fiber support are joined. . (2) positioning and supporting the tip of the optical fiber in the pinhole, and fixing the pinhole and the fiber support;
2. The semiconductor laser/optical fiber coupling device according to claim 1, wherein the semiconductor laser mount and the fiber support are joined through a gap.