JPH06194548A - Photoelectronic device - Google Patents

Abstract

(57) [Summary] [Purpose] To provide an optoelectronic device in which the number of times of optical axis alignment is small and the number of assembling steps is small. The optoelectronic device with a built-in optical isolator has a structure in which a semiconductor laser device 15 and a ferrule assembly 16 having a hermetically sealed structure are connected by a connecting body 17. The ferrule assembly has a structure in which the optical isolator 6 is inserted into the ferrule guide 11 and the ferrule 12 to which the optical fiber 10 is attached is fitted. A wedge-shaped transparent body 32 is provided at the other end of the ferrule guide, and the tip of the optical fiber is an inclined surface. Since the optical isolator having a thickness of 2 mm is used and the condenser lens 24 of the semiconductor laser device has a long focal length, the laser light 2 emitted from the semiconductor laser device 15 is condensed on the way. It is possible to converge on the tip of the optical fiber without providing a lens. As a result, the optoelectronic device has a structure with few optical axis alignment points and a small number of parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optoelectronic device, and more particularly to an optoelectronic device in which the adverse effects of reflected light from a semiconductor laser are eliminated by an optical isolator, and more particularly to a technique effective when applied to an optoelectronic device with a built-in optical isolator.

[0002]

2. Description of the Related Art A semiconductor laser (laser diode: L
D) is widely used as a light source for optical communication and information processing devices. The semiconductor laser generates noise due to the returned light, which is not preferable in terms of system configuration. For example, Nikkei BP
Published by Nikkei Electronics, October 10, 1983
The Japanese issue, P173 to P194, describes that reflected return light from a semiconductor laser causes deterioration of image quality in a video disk. In addition, JP-A-63-
Japanese Patent No. 226987 discloses a semiconductor laser device incorporating an optical isolator for removing reflected return light. This device uses a Faraday rotator that does not use an organic resin, which is an obstacle to guaranteeing long-term reliability. In addition, "The DFB-LD module with a built-in optical isolator" is described in 1985, National Institute of Electronics and Communication Engineers, National Conference on Semiconductor Material Technology 305, Chikama, Watanabe, Miura, and Toge.

On the other hand, regarding the optical isolator, "Opttronics" issued by Optronics, March 1991,
Published on March 10, 1991, it is described in P221.
This document discloses an optical isolator having a diameter of 2.9 mm and a length of 2 mm. Since this optical isolator uses a bismuth substitution type iron garnet crystal, the volume is 1/3 to 1/7 that of the conventional bismuth substitution type isolator, and YIG (yttrium iron garnet) type It is described that it is extremely smaller than 1/20. The optical isolator is described in the catalog (9012-1000) issued by Shin-Etsu Chemical Co., Ltd. Furthermore, the Institute of Electronics, Information and Communication Engineers, IEICE Transactions C-1, May 1990, P323
~ P331 describes an optical isolator for optical communication. In this document, there are "a micro-optical optical isolator having a one-step structure with a backward loss of 30 dB and a two-step structure with a backward loss of 60 dB, and in response to the requirement for high reliability of the optical isolator. The assembling method is from the conventional adhesive to the metal joining direction. "

[0004]

In a semiconductor laser device for optical communication, a semiconductor laser device having an optical isolator built-in has been proposed in order to prevent unstable oscillation of a laser diode due to reflected return light. For example, the DFB-LD module with a built-in optical isolator according to the above document has a structure as shown in FIG. This module
The laser light 2 emitted from the semiconductor laser device 1 is converted into parallel light 4 by the first condenser lens 3, the parallel light 4 is transmitted through the optical isolator 6 fixed in the optical isolator guide 5, and the position is adjusted. The second condensing lens 8 supported by the second condensing lens guide 7 reaches the second condensing lens 8, and the second condensing lens 8 converges the parallel light 4 on the tip of the optical fiber 10 protruding from the tip of the optical fiber cable 9. It is like this. The optical fiber 10 is a single mode optical fiber. In addition, the optical fiber cable 9
Is supported by the ferrule 12 fitted in the ferrule guide 11. Further, the tip of the optical fiber 10 has a ferrule 1 so that the reflected light does not return to the semiconductor laser device 1.
Both the tip of 2 is inclined with respect to the optical axis,
The optical isolator 6 is also arranged so as to be inclined with respect to the optical axis.

However, in the module having such a structure, the optical isolator guide 5, the second condenser lens guide 7 and the ferrule guide 11 need to be highly accurately aligned in the direction perpendicular to the optical axis. At the same time, the ferrule 12 requires high-precision alignment in the optical axis direction in the ferrule guide 11, so that the number of assembling steps increases. In addition, this module has many parts, and it is difficult to reduce the product cost.

An object of the present invention is to provide an optoelectronic device with a built-in optical isolator, which requires less assembly steps. The above and other objects and novel features of the present invention will be apparent from the description of the present specification and the accompanying drawings.

[0007]

The outline of the representative ones of the inventions disclosed in the present application will be briefly described as follows. That is, the optoelectronic device with a built-in optical isolator of the present invention comprises a semiconductor laser device, a ferrule assembly containing an optical isolator, and a tubular connector for connecting the ferrule assembly and the semiconductor laser device. Ferrule assembly
A tubular ferrule guide, an optical isolator inserted and fitted into the ferrule guide, a ferrule inserted and fixed from one end side of the ferrule guide, and an inner diameter hole of the ferrule guide attached to the other end of the ferrule guide. It consists of a transparent body with a wedge-shaped cross section.
An inner diameter portion of the ferrule guide is a straight hole, and an optical isolator having a metal bonding structure with a length of about 2 mm is fitted therein, and a tip portion of the ferrule is inserted therein. An optical fiber cable is concentrically inserted and fixed to the center of the ferrule, and a jacket is removed at the tip of the optical fiber cable to expose the optical fiber. Further, the angle of the inclined surface of the wedge-shaped transparent body and the angle of inclination of the tip of the optical fiber are about 8 ° so that the reflected light does not return to the semiconductor laser element.

[0008]

According to the above means, the optoelectronic device with a built-in optical isolator of the present invention allows the laser light emitted from the condenser lens (first condenser lens) of the semiconductor laser device to be ferruled by the action of the condenser lens. Since the structure is such that the tip end of the optical fiber in the assembly converges, the second condenser lens becomes unnecessary as in the conventional case. As a result, the second
Positioning in the plane direction perpendicular to the optical axis of the second condenser lens guide that supports the condenser lens becomes unnecessary, and the alignment work in the assembling of the optoelectronic device of the present invention requires the distance between the semiconductor laser element and the optical fiber. Since it is determined by the length of the coupling body, only the tip of the optical fiber with respect to the semiconductor laser element, that is, the alignment in the plane direction perpendicular to the optical axis of the ferrule assembly, is required, and the number of assembly steps can be reduced. In addition, the optoelectronic device of the present invention has a reduced number of parts, and can reduce the production cost.

Further, in the optoelectronic device with a built-in optical isolator of the present invention, since the transparent body having the wedge-shaped cross section is attached to one end of the ferrule guide, the inner diameter portion of the ferrule guide into which the optical isolator and the ferrule are inserted is straight. Therefore, the processing cost of the ferrule guide can be reduced.

Further, in the optoelectronic device with a built-in optical isolator according to the present invention, since the laser light is inclined to enter the light incident surfaces of the transparent body, the optical isolator and the optical fiber, the reflected light is reflected. Does not return to the semiconductor laser element, and unstable oscillation in the semiconductor laser can be suppressed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 is a sectional view of an optoelectronic device according to an embodiment of the present invention, FIG. 2 is a sectional view of a ferrule assembly that also constitutes the optoelectronic device, FIG. 3 is a sectional view of the same assembling of the optoelectronic device, and FIG. FIG. 9 is a cross-sectional view showing a state of optical axis alignment in the assembly of FIG. As shown in FIG. 1, an optoelectronic device with a built-in optical isolator according to an embodiment of the present invention includes a semiconductor laser device 15, a ferrule assembly 16, and a connector 17 for connecting the ferrule assembly 16 and the semiconductor laser device 15. It consists of

The semiconductor laser device 15 has a can-sealing structure that is hermetically sealed, and the package is formed by a stem 20 and a cap 21 attached to the main surface side of the stem 20. Also, the stem 2
0 to several leads outside the package as external terminals
2 is protruding. A heat sink 23 is fixed to the main surface of the stem 20 in the package. The semiconductor laser device 1 is fixed to the side surface of the heat sink 23 directly or via a submount (not shown). This semiconductor laser device 1 has a cap 2
Laser light 2 is emitted to the ceiling side of 1 and the main surface side of the stem 20, respectively. A condenser lens 24 is fitted in the ceiling portion of the cap 21. Then, the front laser light 25 emitted from the semiconductor laser device 1 is focused on the tip of the optical fiber 10 in the ferrule assembly 16 as shown in the diagram schematically shown in FIG. As the condenser lens 24, an aspherical lens having a low aberration and a long focal length is used. The focal length of the condenser lens 24 is, for example, about 8 mm. As a result, it is possible to secure a space for alignment with a high degree of coupling and to prevent vignetting of the laser light 2 in the optical isolator 6 described later. A light receiving element 27 is provided on the main surface of the stem 20, and receives the rear laser beam 28 emitted from the semiconductor laser element 1,
The intensity of the laser beam 2 emitted from the semiconductor laser device 1 can be monitored. Further, although not shown, the electrodes of the semiconductor laser device 1 and the light receiving device 27 are electrically connected to the leads 22 via wires or the like not shown. Although the semiconductor laser device 15 has a simple structure in this embodiment, the semiconductor laser device 15 may be of a high-grade type such as cooling the semiconductor laser device 1 with a Peltier device.

As shown in FIG. 2, the ferrule assembly 16 has a tubular ferrule guide 11 having a flange 30, an optical isolator 6 inserted and fitted in a tube (inner diameter hole) of the ferrule guide 11, and the ferrule. The ferrule 12 is hermetically inserted and fixed to one end of the guide 11, that is, the right end in the figure, and the other end of the ferrule guide 11.
In the drawing, the transparent body 32 is airtightly fixed by a glass sealing material 31 to the end surface on the flange 30 side which is the left end. Therefore, the ferrule assembly 16 has a hermetically sealed structure as a whole. Further, the ferrule assembly 16 can be provided to the user even in this state.

The transparent body 32 is made of glass and has a wedge-shaped cross section. This is a transparent body 3
It has a function of changing the direction of the light incident on the inside of the light source 2 and emitting the light.
That is, generally, the ferrule and the single mode optical fiber are obliquely installed or polished so that the laser reflected light at the end face does not return to the semiconductor laser device even a little. In this case, there arises a problem that the optical coupling is lowered.
It is experimentally and theoretically known that, in order to prevent the deterioration of the optical coupling, it is effective to incline the optical axis by ½θ in the opposite direction to the polishing direction, where θ is the polishing angle. There is. From this, the transparent body 32 is θ (θ = 8 °)
It is a wedge-shaped body having an angle. As a result, the laser light 2 is bent by the wedge-shaped transparent body 32, so that the laser light 2 is obliquely incident on the end face of the optical isolator 6. Due to this oblique incidence, the reflected return light at the end face of the optical isolator 6 does not return to the semiconductor laser device 1.

The optical isolator 6 is made of a bismuth substitution type garnet crystal, and a metal junction type having an outer diameter of 2.9 mm and a thickness of 2 mm is used. However, the ferrule assembly 16 closes one end side of the ferrule guide 11 with the ferrule 12 and the other end side of the transparent body 3
Since it is closed by 2 and has an airtight sealing structure, a resin-bonded type can also be used. By thus thinning the optical isolator 6 and by using the condenser lens 24 having a long focus in the semiconductor laser device 15, the laser light 2 condensed by the condenser lens 24 is condensed on the way. Directly without ferrule assembly 16
Can be converged on the tip of the optical fiber 10. This can reduce the number of parts,
Miniaturization of the optoelectronic device can be achieved.

The optical fiber cable 9 is inserted along the center of the ferrule 12, and the jacket 34 of the optical fiber cable 9 is removed at the fitting portion 33 of the ferrule 12 with respect to the ferrule guide 11 to remove the optical fiber 10. Exposed. The exposed optical fiber 10 portion extends along the center of the fitting portion 33 of the ferrule 12. The optical fiber 10 is 7 to 10 μm
A core having a diameter of about 12 and a diameter 12 covering the core (not shown)
A single mode fiber composed of a 5 μm clad (not shown), for example, 1.31 μm band or 1.
It is designed to guide laser light in the 55 μm band. Further, the tip of the optical fiber 10 is formed so as to have a constant angle θ (θ = 8 °) with respect to the optical axis as in the case of the transparent body 32. In order to give an angle of θ to the tip of the optical fiber 10, the tip of the fitting portion 33 of the ferrule 12 is also an inclined surface having an angle of θ. The transparent body 3
Since 2 is a wedge-shaped body having an angle of θ and the tip of the optical fiber 10 is an inclined surface that is θ in a direction opposite to the inclination direction of the transparent body 32, it is shown in FIG. As described above, the laser light 2 incident on the transparent body 32 is 1 / 2θ
When refracted downward in FIG. 2 and incident on the inclined surface of the optical fiber 10, the laser light 2 is refracted upward in FIG. Further, since the wedge-shaped transparent body 32 and the optical fiber 10 having the tip inclined, the optical isolator 6 does not need to be inclined as in the conventional case, and the fitting portion 33 of the ferrule 12 and the optical isolator 6 are inserted. The inner diameter hole of the ferrule guide 11 to be formed can be a straight hole.
Since the inner diameter hole is a straight hole, the machining is easier and the cost of the ferrule guide 11 is reduced as compared with the machining of the inner diameter hole bent in the middle. Further, the optical isolator 6 and the ferrule 12 can be easily attached to the straight hole.

The connecting body 17 is a tube made of metal such as Kovar, and one end thereof has a stem 20 of the semiconductor laser device 15.
It is airtightly fixed to the portion, and the other end is airtightly fixed to the flange 30 portion of the ferrule assembly 16. Fixing is done by welding.

Next, the assembly of such an optoelectronic device with a built-in optical isolator will be described. As shown in FIG. 3, although not particularly limited, first, the semiconductor laser device 1
5 and the connecting body 17 are joined. The joining is performed by ring weld welding or the like, and one end and the entire circumference of the coupling body 17 made of a tubular body is hermetically connected to the entire circumference of the stem 20 of the semiconductor laser device 15. It may be fixed by silver brazing or soldering.

Next, as shown in FIG. 3, the ferrule assembly 16 is pressed against the opened connecting body 17 in the direction of the arrow. The distance between the semiconductor laser device 1 or the condenser lens 24 of the semiconductor laser device 15 and the tip of the optical fiber 10 in the ferrule assembly 16 is automatically determined by the length of the connecting body 17. Therefore, positioning is performed in the plane direction perpendicular to the optical axis, that is, the laser beam 2. Then, the entire circumference of the flange 30 of the ferrule assembly 16 is hermetically fixed over the entire circumference of the end face of the coupling body 17 by laser welding. This completes the optoelectronic device shown in FIG.

[0020]

【The invention's effect】

(1) An optoelectronic device with a built-in optical isolator according to the present invention comprises a semiconductor laser device that collects laser light emitted from a semiconductor laser element by a condenser lens and emits the laser light to the outside of the package. The transparent lens and the optical isolator sequentially pass through the emitted laser light, and the ferrule assembly receives the tip of the optical fiber, and the connecting body that connects the ferrule assembly and the semiconductor laser device. The use of an aspherical lens increases the focal length, and the optical isolator used in the ferrule assembly has a thin thickness of 2 mm, which allows for downsizing, and the laser light transmitted through the condenser lens can be reduced. Even if a condenser lens is not provided on the way, the effect of being able to focus directly on the tip of the optical fiber is achieved. It is.

(2) According to the above (1), the optoelectronic device of the present invention has a structure in which the laser light emitted from the semiconductor laser element can be condensed by the condensing lens and directly converged on the tip of the optical fiber. Therefore, in the assembly work for connecting the semiconductor laser device and the ferrule assembly with the connecting body, the dimension in the optical axis direction is uniquely determined by the length of the connecting body. The effect that the reduction of the man-hour can be achieved is obtained.

(3) According to the above (1), in the optoelectronic device of the present invention, the laser light emitted from the semiconductor laser element can be condensed by the condenser lens and directly condensed at the tip of the optical fiber. It is not necessary to dispose a lens or the like, and the effect of reducing the number of parts can be obtained.

(4) In the optoelectronic device of the present invention, the laser light emitted from the semiconductor laser device enters the optical isolator by changing the optical axis by 1 / 2θ through a wedge-shaped transparent body, and then the tip is inclined. Since the laser light travels to the tip of the optical fiber, the laser light is obliquely incident on the incident surface of each component without being orthogonal to the incident surface, so that it is difficult to return the reflected light to the semiconductor laser element.

(5) In the ferrule assembly of the optoelectronic device of the present invention, it is not necessary to tilt the optical isolator due to the use of the wedge-shaped transparent body and the inclined surface of the tip of the optical fiber. Therefore, the optical isolator and the ferrule are not necessary. Since the inner diameter hole of the ferrule guide for inserting the mating part can be made a straight hole, it is possible to reduce the processing cost compared to hole processing that is bent in the middle, and it is easy to attach the optical isolator and ferrule. The effect that there is is obtained.

(6) In the ferrule assembly of the optoelectronic device of the present invention, the optical isolator has an airtight structure. Therefore, there is a possibility that gas may be generated due to a change over time, but an effect that an inexpensive resin-bonded optical isolator can be used is obtained.

(7) Due to the above (1) to (6), according to the present invention, it is possible to provide a low cost optical isolator built-in type optoelectronic device having a small number of optical axis alignment and a small number of parts. Is obtained.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say, for example,
FIG. 5 is a cross-sectional view of ferrule assembly 16 according to another embodiment of the present invention. In this ferrule assembly 16, the transparent body 32 is not a wedge-shaped one but a flat plate whose manufacturing cost is low. Since it is a flat transparent body 32, in order to prevent reflection of the laser light 2,
The transparent body 32 is inclined with respect to the optical axis. in this case,
Since the laser light 2 travels straight without being refracted even after passing through the transparent body 32, it is desirable to arrange the optical isolator 6 in an inclined manner. The optoelectronic device of this embodiment can also obtain the same effect as the above embodiment. However, since the optical axis does not incline in the opposite direction to the polishing direction of the optical fiber 10, there arises a problem of deterioration of optical coupling.

FIG. 6 is a cross-sectional view of ferrule assembly 16 according to another embodiment of the present invention. In this ferrule assembly 16, the transparent body 32 has a lens structure. The optoelectronic device of this embodiment can also obtain the same effect as the above embodiment. 5 and 6, a hole inclined with respect to the optical axis is directly provided in the ferrule guide 11 in order to insert the optical isolator 6, but if the processing is troublesome, the optical isolator 6 may be tubular. The guide may be inserted into the guide and the guide may be inserted into a hole that coincides with the optical axis of the hole into which the fitting portion 33 is inserted. in this case,
The axial direction of the inner diameter of the guide is inclined with respect to the axial direction of the outer diameter.

In the above description, the case where the invention made by the present inventor is mainly applied to the semiconductor laser for optical communication which is the background field of application has been described.
The present invention is not limited to this, and can be applied to, for example, a semiconductor laser for information processing having a short wavelength. The present invention can be applied to at least an optoelectronic device having a semiconductor laser that dislikes returning light.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an optoelectronic device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a ferrule assembly according to one embodiment of the present invention.

FIG. 3 is a cross-sectional view showing the assembly of an optoelectronic device according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view showing an optical axis alignment state in assembling an optoelectronic device according to an embodiment of the present invention.

FIG. 5 is a sectional view showing a ferrule assembly according to another embodiment of the present invention.

FIG. 6 is a sectional view showing a ferrule assembly according to another embodiment of the present invention.

FIG. 7 is a cross-sectional view showing a conventional DFB-LD module with a built-in optical isolator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Semiconductor laser element, 2 ... Laser light, 3 ... 1st condensing lens, 4 ... Parallel light, 5 ... Optical isolator guide, 6 ... Optical isolator, 7 ... 2nd condensing lens guide, 8 ... 2nd condensing Lens, 9 ... Optical fiber cable, 10 ... Optical fiber, 11 ... Ferrule guide, 12 ... Ferrule, 15
... semiconductor laser device, 16 ... ferrule assembly, 1
7 ... Connection body, 20 ... Stem, 21 ... Cap, 22 ... Lead, 23 ... Heat sink, 24 ... Condensing lens, 25 ...
Front laser light, 27 ... Light receiving element, 28 ... Rear laser light,
30 ... Flange, 31 ... Glass sealing material, 32 ... Transparent body,
33 ... Fitting part, 34 ... Jacket, 40 ... Lens.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location H04B 10/12 (72) Inventor Masato Tozawa Kashiwagi, Nagano Prefecture 190 Kashiwagi, Todaishita 190 Inc. (72) Inventor, Yasuhisa Senba, Asahidai, Moroyama-cho, Iruma-gun, Saitama Prefecture, Hitachi, Ltd.

Claims (7)

[Claims] 1. A ferrule assembly in which an optical isolator is fitted in a tubular ferrule guide and a ferrule having an optical fiber attached to one end of the ferrule guide is inserted and fixed, and laser light is externally emitted via a condenser lens. An optoelectronic device comprising: a semiconductor laser device that emits light; and a connecting body that connects the semiconductor laser device and the ferrule assembly. 2. The optoelectronic device according to claim 1, wherein the laser light emitted from the semiconductor laser device is converged on the tip of an optical fiber by a condenser lens of the semiconductor laser device. 3. The optoelectronic device according to claim 1, wherein a transparent body that transmits laser light is disposed on an end face of the ferrule guide facing the semiconductor laser device. 4. The photoelectron according to claim 3, wherein the laser light emitted from the semiconductor laser device is configured not to be orthogonal to the end faces of the transparent body, the optical isolator and the optical fiber. apparatus. 5. The transparent body has a wedge-shaped cross section, and is arranged so that laser light emitted from a semiconductor laser device enters the surface of the sealing body at an angle. Item 3. The optoelectronic device according to Item 3. 6. The optoelectronic device according to claim 3, wherein the transparent body is a lens. 7. The optoelectronic device according to claim 5, wherein an inner diameter portion of the ferrule guide into which the optical isolator and the ferrule are inserted is a straight hole.