JP2000121886A - Optical coupling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical coupling device that the optical coupling between a semiconductor element and an optical fiber can be stably performed and which is small in size and which can be assembled with easy works. SOLUTION: Relating to an optical coupling device having a pipe 7 which is provided at the side face of a case 6 in inside which a laser diode 1 and a photodiode 2 are provided and to which a lens holder 13 is attached, the pipe 7 is provided in roughly the same direction as that of the base 15 prolonged from the side face of the case 6 and is shorter than the length of the base 15 and the base 15 is divided into at least two parts from the case 6 to be protuded and holes 16 for screw tightening and fixing are provided respectively at bases 15 divided into two parts. Moreover, roughly all surroundings of the lens holder 13 are fixed to the end surface of the pipe 7 with laser beam weldings 19 through the space between bases 15 divided into two parts and the holes 16 for screw tightening and fixing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical coupling device which is used, for example, as a light source for optical communication and optically couples a semiconductor element and an optical fiber via a lens.

[0002]

2. Description of the Related Art The structure of a conventional optical coupling device is disclosed in
There is a structure described in JP-A-224100. In this method, optical coupling between a semiconductor laser and an optical fiber is performed via a lens and an optical isolator. That is, a semiconductor laser, a monitoring photodiode, a temperature detecting chip thermistor, and a lens mounted on a chip carrier are respectively mounted on a base. An optical isolator is fixed to the distal end of the lens installed on the pedestal, and a ferrule having an optical fiber provided therein is fixed to the distal end of the optical isolator via a slide ring by welding. These are mounted in a metal case via a Peltier element. The ferrule and the metal case are connected and sealed with solder.

[0003]

However, the above prior art has the following problems.

That is, an optical isolator and a ferrule are welded and fixed to a base on which a semiconductor laser and a lens are mounted.
Furthermore, since the ferrule is soldered to the metal case and all of them are mounted on the Peltier element via the pedestal, the heat capacity for controlling the temperature with the Peltier element increases,
Temperature control of the semiconductor laser cannot be performed with high accuracy. In addition, there is also a disadvantage that the installation of the optical isolator in the metal case increases the size of the device.

An object of the present invention is to provide an optical coupling device that can stably perform optical coupling between a semiconductor element and an optical fiber and that can be assembled with a small size and easy operation.

[0006]

In order to achieve the above object, the present invention provides a semiconductor device comprising at least one of a semiconductor light emitting device and a semiconductor light receiving device, a substrate member on which the semiconductor device is mounted, and a semiconductor device. An optical fiber that is optically coupled to the element and internally transmits laser light, a lens mounted on the substrate member, and a lens that optically optically couples the semiconductor element and the optical fiber; and the semiconductor element and the optical fiber. Another lens for optically coupling the lens, a lens holder for holding and fixing the lens, a box-shaped case for mounting and housing the semiconductor element therein, and a box forming the bottom surface of the box-shaped case A base provided with holes for screw fixing at portions protruding from the side of the mold case and a lens holder mounted on the side of the box-shaped case and having the lens holder attached thereto; That and a pipe, the pipe,
The pipe is installed in substantially the same direction as the base extended from the side surface of the box-shaped case, the pipe is shorter than the length of the base extended from the box-shaped case, and the base is at least two pieces away from the box-shaped case. The two divided bases are provided with screw fixing holes, respectively, and the lens holder is provided on the pipe end surface between the two divided bases and the base. Almost the entire periphery is fixed by laser welding through the screw fixing holes provided in.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. In each of the drawings, some components, laser welding, and the like are omitted as appropriate in order to avoid complication.

FIG. 1 is a longitudinal sectional view showing an example of the entire structure of the optical coupling device of the present invention, and FIG. 2 is a bottom view showing the same.

In FIG. 1, the optical coupling device has a laser diode 1 as a semiconductor light emitting element, a photodiode 2 as a semiconductor light receiving element, and a lens 3 mounted on a stem 4. This stem 4 is attached to the base 15 in the case 6.
Is installed via a temperature cooling element 5. The temperature cooling element 5 includes a laser diode 1 and a photodiode 2
Is provided to control the temperature so as to keep the temperature constant. An optical fiber 10 that is optically coupled to the laser diode 1, the photodiode 2, and the lens 3 and transmits the laser light to the inside or the outside, and a ferrule 12 having an optical fiber coating 11 provided therein are guided by a guide 14. Supported. Further, a lens provided with a pipe 7 attached to the side surface of the case 6, a rod lens 9 joined to an end face of the pipe 7 and internally having a laser diode 1, an optical fiber 10 optically coupled thereto, and an optical isolator 8. A holder 13 is provided. The guide 14 described above is attached to the lens holder 13. The optical coupling between the laser diode 1 and the photodiode 2 and the optical fiber 10 is performed by an optical isolator 8 and two lenses 3 and 9.

The case 6 is made of, for example, a metal material and a ceramic material having a box shape, and has a total of 16 lead terminals (not shown), eight on each side. A cap 18 for shutting off the inside and the outside of the case 6 is joined to the upper surface of the case 6. The dimensions of the box-shaped case 6 are, for example, 6.5 mm in height (vertical direction on the paper surface in FIG. 1) and 1 in width (vertical direction on the paper surface in FIG. 1).
2.7 mm, length (transverse direction of paper surface in FIG. 1) 21.0 m
m, and the lead terminals (not shown) are, for example, 2.
They are provided at 54 mm intervals.

The base 15 that forms the bottom surface of the case 6 includes
The case 6 is formed so as to extend and protrude from both sides of the case 6 (lateral direction of the paper surface in FIG. 1), and a screw hole 16 is formed in the protruding portion. The base 15 projecting toward the pipe 7 attached to the side surface of the case 6 is divided into two parts so that a part of the pipe 7 can be seen, and the base 15 projecting to the opposite side is not divided. It is formed in an extended state. The screw fixing hole 16 formed in the base 15 is, for example, φ2.6 m.
m.

In the optical coupling device, the base 15 is attached to a heat sink or the like having excellent heat dissipation by screwing, and is mounted on a printed circuit board. The base 15 is provided with a groove 17 on the surface that comes into contact with the heat sink, so that the deformation of the case 6 when screwed and fixed is absorbed by the groove 17 so that the optical coupling system is not displaced. .

The stem 4 is a metal member. On its upper surface, a laser diode 1, a photodiode 2, a lens 3 for optically coupling the laser diode 1 and the optical fiber 10, and a chip thermistor for temperature detection (not shown) , And an adjustment resistor such as a thin film resistor (not shown).
The laser diode 1 and the lens 3 are provided with a step at a portion where the lens 3 is mounted so that their optical axes coincide with each other. The stem 4 is installed on the base 15 in the case 6 via the temperature cooling element 5. The temperature cooling element 5 is controlled by detecting the temperature with a chip thermistor (not shown) mounted on the stem 4 so as to keep the temperatures of the laser diode 1 and the photodiode 2 constant.

The pipe 7 is a metal member, and is fixed to the case 6 in advance by silver brazing (not shown) before the lens holder 13 is mounted (described later).

The lens holder 13 is a metal member, in which the optical isolator 8 and the rod lens 9 are fixed in advance by a joining member such as solder.

When the lens holder 13 is attached to the pipe 7, the lens holder 13 holding and fixing the optical isolator 8 and the rod lens 9 is positioned so that the laser light passing through the lens 3 is incident on the optical fiber 10. After the adjustment (adjustment so that the output of the optical fiber 10 at that time is maximized), the lens holder 13 is fixed to the end face of the pipe 7 by laser welding 19.

The ferrule 12 is composed of a zirconia member (not shown) for internally fixing the optical fiber 10 and a metal member for fixing the optical fiber coating 11. When attaching the ferrule 12 to the guide 14, the condensed laser light passing through the lens 3, the optical isolator 8, and the rod lens 9 is
The ferrule 12 is first fixed to the guide 14 by laser welding (not shown) after adjusting the position so that the output of the optical fiber 10 is maximized at that time. Next, the guide 14 is laser welded 19 to the end face of the lens holder 13.
It is fixed by welding.

The tip of the optical fiber 10 exposed at the tip of the ferrule 12 is processed obliquely to prevent the laser light oscillated from the laser diode 1 from returning to the laser diode 1 as reflected return light at the tip of the optical fiber 10 (not shown). Zu) has been. In order to make the laser light incident on the obliquely processed optical fiber 10 efficiently, the laser light is obliquely shifted by relatively moving the optical axes of the laser diode 1, the lens 3, the optical isolator 8, and the rod lens 9 by several tens of μm. The stem 4 on which the laser diode 1 and the lens 3 are mounted is displaced from the center of the case 6 so that the laser light passing through the lens 3 is emitted obliquely. Further, by shifting the optical axes of the laser diode 1, the lens 3, the optical isolator 8, and the rod lens 9 relatively by several tens of μm, the reflected return light of the laser light reflected at the incident end of the optical isolator 8 and the rod lens 9 Is also preventing.

FIG. 3 shows a comparison of the case where the groove 17 is formed in the base 15, which is one of the features of the optical coupling device of this embodiment.
Shown in

In FIG. 3, the horizontal axis is the base 1 shown in FIG.
5 shows the position of AA 'on the back surface. The vertical axis is base 1
5 shows the displacement amount on the back surface as a relative value. The amount of displacement is
The deformation of the base 15 when the optical coupling device is screwed and fixed to a member such as a heat sink is obtained by calculation.

As can be seen from FIG. 3, the portion of the base 15 protruding from the case 6 is greatly deformed. When the groove 17 is provided on the back surface of the base 15, the displacement is larger than when the groove 17 is not provided. That is, by providing the groove 17 on the back surface of the base 15, the deformation at the groove 17 is increased, the deformation applied to the case 6 is reduced, and the displacement of the optical coupling system can be prevented.

As the shape of the groove 17 formed on the back surface of the base 15, for example, when the thickness of the base 15 is 1.0 mm,
Immediately below the side of Case 6, 1.0 mm wide and 0.5 mm deep
A groove 17 having a moderate shape is desirable. However, the present invention is not limited to this, and the installation position, width and depth of the groove 17 are appropriately determined by the shapes of the case 6 and the base 15.

Next, details of the laser welding 19 around the entire circumference of the pipe 7 and the lens holder 13, which is another feature of the optical coupling device of the present embodiment, will be described with reference to FIGS.

FIG. 4 shows a method of mounting the optical coupling device of FIG. 1 vertically and fixing the lens holder 13 to the end surface of the pipe 7 on the side surface of the case 6 by laser welding 19, and FIG.
FIG. 4 is a front view of the end face of the pipe 7 as viewed from the front, and shows a welding sequence for laser welding 19 of the lens holder 13. FIG. 6 shows the relationship between the increase of 19 laser welding points shown in FIG. 5 and the change in light output.

In FIG. 4A, a lens holder 13 holding and fixing an optical isolator 8 and a rod lens 9 is positioned and installed on an end face of a pipe 7 attached to a side surface of a case 6. The position adjustment of the lens holder 13
As described above, the laser beam transmitted from the laser diode 1 and the lens 3 mounted on the stem 4 in the case 6 is made incident on an optical fiber (not shown), and the position is adjusted so that the optical fiber output becomes maximum. Do. Position adjustment is performed in a non-contact state with the lens holder 13 separated from the end face of the pipe 7 by about 10 to 20 μm. After the position adjustment, the lens holder 13 and the end face of the pipe 7 which are separated by about 10 to 20 μm
In this state, laser irradiation 20 is performed and the lens holder 13 is fixed to the end face of the pipe 7 by laser welding 19. Next, the laser welding 19 is performed while sequentially rotating the case 6.
Is repeated, and substantially the entire periphery of the lens holder 13 is welded (FIG. 4B).

FIG. 5 shows the lens holder 13 on the end face of the pipe 7.
Are shown in the order of laser welding 19. A laser irradiation head (not shown) branched into three at 120 ° intervals with respect to the center axis of the lens holder 13 is arranged, and the irradiation head irradiates a laser beam 20. These irradiation heads are fixed, and in order to weld substantially the entire periphery, the rotation of the optical coupling device is performed by rotating the center axis of the case 6 side while correcting the center axis of the lens holder 13 as needed so that the center axis of the lens holder 13 becomes the center of rotation. Do it. Laser welding 19 of the lens holder 13 simultaneously emits laser light from the three-branched laser irradiation head.
Then, laser welding 19 is performed on 24 points around the entire circumference while increasing the welding points by three points.

The welding order of the laser welding 19 is represented by a numeral in a circle in the drawing, and the position of the first welding point is. A point is irradiated with the laser 20 slightly obliquely from the upper surface (upper side of the paper surface in FIG. 5) of the case 6 and the base divided into two parts from the bottom surface (lower side of the paper surface in FIG. 5) of the case 6 Fifteen
The laser irradiation 20 is performed during the interval. The next point is that the case 6 is rotated about 60 ° from the point and the laser irradiation 20 of the point is performed.
Laser welding 19 is performed in the same manner as described above. However, case 6
The two points on the bottom surface side are irradiated with laser 20 through a screw fixing hole 16 provided in the base 15. further,
The next point is rotated about 75 ° so that it returns to the point of the laser welding point from point to point.
I do.

Thereafter, laser welding is repeatedly performed while rotating the case 6 to the point at intervals of 15 °. However,
In the point 20 and the laser irradiation 20 of the point, each of the points 'and' becomes an unwelded point because the base 15 other than the screw fixing hole 16 becomes an obstacle. In this case, the number of laser welding points 19 is reduced from three to two at the same time, and the welding balance is lost, which tends to cause displacement. However, the authors have found that by controlling the welding order optimally, no displacement occurs. Have confirmed.

FIG. 6 is a diagram showing the relationship between the increase in 19 laser welding points shown in FIG. 5 and the change in light output. In the figure, the horizontal axis represents the increase in the number of welding points, and the vertical axis represents the light output loss at that time as a relative value.

As can be seen from FIG. 6, the light output loss changes relatively greatly from the initial stage to three-point welding and six-point welding, but almost does not increase even when the number of welding points increases from around 9-point welding or 12-point welding. No big change. As described above, by adopting a welding procedure in which an unwelded portion is formed after the light output is stabilized, almost the entire periphery can be fixed by laser welding without increasing the light output loss.

The effect of the embodiment constructed as described above will be described below.

The effect of the structure in which the groove 17 is provided on the back surface of the base 15 is as follows. When the optical coupling device is fixed to a member such as a heat sink by screwing, the deformation of the base 15 projecting from the case 6 is provided by the groove 17. Accordingly, the case 6 can be largely deformed, the deformation occurring in the case 6 can be reduced, and the optical coupling system can be prevented from being displaced. This eliminates a change in optical output when the optical coupling device is fixed by screwing, and enables stable optical coupling between the laser diode 1 and the optical fiber 10.

When laser welding is performed, laser irradiation 20 can be performed between the screw fixing hole 16 and the base 15, and the lens holder 13 is attached to the end face of the pipe 7 by substantially all-around laser welding 19.
it can. In particular, even when the pipe 7 is shorter than the protruding length of the base 15, the laser welding 19 can be performed on substantially the entire periphery, and the apparatus can be significantly reduced in size. Further, since the laser diode 19 can be firmly fixed, the optical coupling between the laser diode 1 and the optical fiber 10 can be stably performed over a long period of time.

Further, the lenses 3, 9 for optically coupling the laser diode 1 and the optical fiber 10 are divided into a lens 3 mounted on the temperature cooling element 5 in the case 6 and a lens 9 installed outside the case 6. Thereby, the height of the device can be reduced and the device can be made thinner. As a result, even when a plurality of lenses 3, 9 and an optical isolator 8 are used for optical coupling between the laser diode 1 and the optical fiber 10, the device can be easily assembled without increasing the size of the device. Optical coupling between the optical fiber 1 and the optical fiber 10 can be performed stably.

In the above embodiment, an optical coupling device having both a laser diode 1 and a photodiode 2 as semiconductor elements has been described as an example. However, the present invention is not limited to this, and only one of them is provided. The same effect can be obtained.

In the above embodiment, the base 15
As the shape of the groove 17 formed on the back surface of the case 6, two grooves are formed in parallel with the lateral direction of the case 6, but the shape is not limited thereto. For example, the grooves 17 may be provided in the lateral direction and the vertical direction of the case 6, Further, the optical coupling system may be formed not on the back surface of the base 15 but on the front surface or the bottom surface in the case 6, so that the displacement of the optical coupling system when the base 15 is fixed by screwing can be reduced, and the same effect can be obtained.

Furthermore, in the above embodiment, as shown in FIG. 5, the procedure for welding the lens holder 13 to the end face of the pipe 7 is shown. Approximately the entire circumference can be fixed by the laser welding 19 without increasing the number of laser beams, so that the same effect can be obtained.

Further, in the above embodiment, the laser diode 1, the photodiode 2, and the optical fiber 10
Although the optical coupling device that performs the optical coupling by the two lenses 3 and 9 has been described as an example, the present invention is not limited to this. That is, even with a coupling optical system using one lens, the same configuration as that of the above-described embodiment can be applied to the laser welding 19 of substantially the entire circumference on the side surface of the case 6 and the formation of the groove 17 on the back surface of the base 15. In these cases, similar effects can be obtained.

[0039]

As described above, according to the present invention, the optical coupling between the laser diode and the optical fiber can be stably performed, and the assembly can be performed by a small and easy operation.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view illustrating an entire structure of an optical coupling device according to an embodiment of the present invention.

FIG. 2 is a bottom view showing the entire structure of the optical coupling device shown in FIG.

FIG. 3 is a comparison diagram of a displacement amount when a groove is provided on the bottom surface of the optical coupling device shown in FIGS. 1 and 2;

FIG. 4 is a longitudinal sectional view showing a main part of a laser welded portion structure of the optical coupling device shown in FIG.

FIG. 5 is a side view showing a main part of a laser welding structure of the optical coupling device shown in FIG. 1;

6 is a diagram illustrating an increase in laser welding points and a change in light output of the optical coupling device illustrated in FIG. 5;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Laser diode (semiconductor light emitting element), 2 ... photodiode (semiconductor light receiving element), 3 ... lens, 4 ... stem, 5 ... temperature cooling element (Peltier element), 6 ... case,
7 ... pipe, 8 ... optical isolator, 9 ... rod lens,
DESCRIPTION OF SYMBOLS 10 ... Optical fiber, 11 ... Optical fiber coating, 12 ... Ferrule, 13 ... Lens holder, 14 ... Guide, 15 ... Base, 16 ... Screw hole, 17 ... Groove, 18 ... Cap, 19
... laser welding, 20 ... laser irradiation light.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tetsushi Sueshima 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the Information and Communication Division, Hitachi, Ltd. (72) Keiichi Yamada 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Address Co., Ltd.Hitachi, Ltd.Information and Communication Division (72) Inventor Hideyuki Kuwano 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture, Ltd.Information and Communication Division, Hitachi, Ltd. Address F-term in Hitachi Research Institute, Ltd. F-term (reference) 2H037 AA01 BA03 BA12 CA16 DA04 DA05 DA15 DA17 DA35 DA38 5F073 AB27 AB28 BA02 FA05 FA07 FA08 FA25 5F088 AA01 BB01 JA05 JA12 JA14

Claims (4)

[Claims] 1. A semiconductor device comprising at least one of a semiconductor light emitting device and a semiconductor light receiving device, a substrate member on which the semiconductor device is mounted, and an optical fiber optically coupled to the semiconductor device for internally transmitting laser light. A lens mounted on the substrate member and optically coupling the semiconductor element and the optical fiber; another lens for optically coupling the semiconductor element and the optical fiber; and A lens holder for holding and fixing, a box-shaped case for mounting and storing the semiconductor element therein, and a screw-fixing portion for forming a bottom surface of the box-shaped case and extending from a side surface of the box-shaped case and projecting therefrom. In a light coupling device having a base provided with a hole, and a pipe installed on a side surface of the box-shaped case and to which the lens holder is attached, the pipe is It is installed in substantially the same direction as the base extended from one side surface of the box-shaped case, is shorter than the length of the base extended from the box-shaped case, and the pipe-side base is at least from the box-shaped case. 2
The two divided bases are provided with screw fixing holes respectively in the two divided bases, and the lens holder is fixed to the end face of the pipe by laser welding substantially all around. Optical coupling device. 2. The optical coupling device according to claim 1, wherein the base has a plurality of protrusions extending from a side surface of the box-shaped case, and the protrusions have at least one screw fixing hole. An optical coupling device, comprising: 3. The optical coupling device according to claim 1, wherein said substrate member is installed in said box-shaped case via a temperature cooling element for controlling the temperature of said semiconductor element. Coupling device. 4. The optical coupling device according to claim 1, wherein the base has a plurality of grooves on a surface on which the substrate member is mounted or on a rear surface thereof.