JPH1039174A - Semiconductor laser module device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize an optical system over a long time by integrally assembling a condenser lens and an optical isolator and constituting a metallic holder of a large thickness with which sufficiently strength is assured within a limited range of metallic holder diameter. SOLUTION: This non-temp. control semiconductor laser module device has a semiconductor laser element 11, a metallic stem 12, a condenser lens 13, the first metallic holder 15 and the optical isolator 18. The condenser lens 13 condenses the exit light from the semiconductor laser element 11 to an optical fiber 17 and the optical isolator 18 removes the influence of the reflected return light from the optical fiber 17 on the semiconductor laser element 11. The condenser lens 13 and the optical isolator 18 are fixed to the metallic holder 15, by which the constitution of the thickness part 15d of the metallic holder 15 to the large thickness at which the sufficient strength is assured is made possible within the range of the external shape of a metallic stem 12 and the holder diameter R limited to the side inner than the notched part 12a formed at the metallic stem 12 for the purpose of automatic recognition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a semiconductor laser module device.

[0002]

2. Description of the Related Art A recent technological revolution in a trunk optical communication system is remarkable.
FB-LD (distributed feedback laser diode), high efficiency,
With the development and commercialization of an APD (avalanche photodiode) that simultaneously expresses high sensitivity, an optical communication system of 2.5 Gb / s has already reached practical use.

As the performance of the semiconductor light emitting and receiving elements used in these optical communication systems has been improved, the system itself has been studied for higher performance (longer distance and larger capacity) as well as lower cost and smaller size. Some are being realized. Among them, STM-1 to STM-4 (155Mbps)
622 Mbps), it is -40 to 40% to reduce the size and cost of the entire device.
FP LD (Fabry-Perot LD) and DF that operate without temperature control even in a severe temperature environment of + 85 ° C
B LD (Distributed Feedback)
LD) is being put to practical use.

Under such circumstances, STM-16 has been developed as a further development of an optical communication system operating without temperature control.
There is a demand for the development of a semiconductor laser module that does not perform temperature control even in a high-speed region (2.5 Gbps). In the area of STM-16 (2.5 Gbps), D
Application of FBLD is indispensable, but generally DFB LD
It is pointed out that, while having excellent spectral characteristics, the anti-reflection coating is applied to the front light output end face, so that the resistance to reflected return light is poor. Therefore, especially 1
In the region of the transmission rate exceeding Gbps, it is necessary to insert an optical isolator into the optical system to remove the influence of the externally reflected return light on the semiconductor laser.

FIG. 3 is a sectional view showing a conventional non-temperature-adjustable semiconductor laser module having a built-in optical isolator. FIG.
As shown in the figure, the semiconductor laser element 31 is soldered to the metal stem 32 via the heat sink 131 by soldering,
It is hermetically sealed using a cap 133 with a lens. A monitoring photodiode is mounted on the metal stem 32, and a condenser lens 33 is mounted on the cap 133.

In a normal case, gold plating is applied to the metal stem 32 to prevent corrosion. Therefore, when welding and fixing the cap 133 with the lens and the metal stem 32 to each other, a crack is easily generated in the welded portion by the gold plating. A resistance welding method is used in which the steps are simpler than the YAG welding method and gold plating can be effectively used. In addition, the screening of individual semiconductor laser elements and the removal of defective elements by characteristic selection are performed with the lens-mounted cap 133 fixed by welding.

The output light from the semiconductor laser element 31 is supplied to a condenser lens 33 fixed to a cap 133 with a lens.
Is adjusted to the optical fiber 37 via the optical isolator 38. The optical isolator 38 is held by an isolator holder 138. The isolator holder 138 accommodates a cap 133 in a recess 130, and is fixed to the metal stem 32 by welding on the outer peripheral side of the cap 133. The optical fiber 37 is held by a metal sleeve 137, and the metal sleeve 137 is fixed to the isolator holder 138 by welding.

For the welding and fixing between the isolator holder 138 and the metal sleeve 137, and between the metal sleeve 137 and the optical fiber 37, YAG welding is used, which requires a long time in the process but enables high-precision welding with high positional accuracy and high reliability. Is often done.

FIG. 4 is a sectional view showing a semiconductor laser module having a built-in optical isolator described in Japanese Patent Application Laid-Open No. 4-97306. As shown in FIG. 4, a lens 45 is attached to the lens holder 46, and an optical isolator 49 is attached near the lens 45.

The light emitting element 41 is fixed to an L-shaped support plate 44 via a heat sink 42 and a light emitting element header 43. On the other hand, the lens holder 46 adjusts the optical axis of the light emitting element 41, the lens 45, and the optical isolator 49, and is fixed to the support plate 44 via the sleeve 47.

The light emitted from the light emitting element 41 is converted into a parallel beam by a lens 45, passes through an optical isolator 49, is adjusted in optical axis to an optical fiber 412 by a second lens 411, and the second lens 411 and the optical fiber 412 are made of metal. It is held by the sleeve 47.

In the structure shown in FIG. 4, since the lens 45 and the optical isolator 49 are mounted close to the lens holder 46, the light emitted from the light emitting element 41 is adjusted by the lens 45 so as to become a parallel beam. , Lens 4
Without adjusting the optical axis of the optical isolator 49 with the optical isolator 49,
An optical system can be configured.

[0013]

However, in the conventional semiconductor laser module having a built-in optical isolator shown in FIG. 3, the lens 33 and the optical isolator 38 are fixed to the stem 32 and the isolator holder 138 which are different metal housings. Therefore, there is a problem that it is difficult to secure long-term stable operation of the optical system.

This is because the sharing of members is centered on the non-temperature-controlling coaxial module such as a visible laser or an FP-LD, so that there is a substantial upper limit on the allowable external dimensions. to cause. For example, the outer dimensions of the metal stem 32 on which the semiconductor laser element 31 and the heat sink 131 are mounted are 5.6 mmφ, and it is not an exaggeration to say that they are almost unified.

Therefore, when an optical system is configured by fixing the condenser lens 33 and the optical isolator 38 to different metal housings, the metal housing which is one of the important factors for stabilizing the optical system is provided. It becomes difficult to increase the body thickness.

The metal stem 32 is formed with a plurality of cutouts on its outer peripheral edge for automatic recognition and holding of an automatic assembly line. The isolator holder 138 stores the cap 133 in the recess 138a, and
Is fixed to the metal stem 32 by welding at the opening edge thereof, the outer diameter of the opening edge of the concave portion 138a becomes larger than the outer diameter of the metal stem 32, and the isolator holder 138 is used for resistance welding.
Of the opening edge of the metal stem 32 overlaps the notch of the metal stem 32,
Welding is performed at the notch, causing abnormal melting.

This is because the contact resistance of the notch of the metal stem 32 is maximized, causing a local current concentration during resistance welding, and the welding state is biased as compared with a portion having no notch.

Not only does the welding strength become non-uniform due to such abnormal welding, but also metal debris and the like are generated in locally over-melted portions, which enter the space of the isolator holder 138. Therefore, they may adhere to the optical axis, which is one of the causes of deteriorating the stability of the optical coupling system.

In the structure shown in FIG. 4, the lens 45 and the optical isolator 49 are fixed to the lens holder 46, and the optical system is configured so that the light emitted from the light emitting element 41 is converted into a parallel beam by the lens 45. In this case, it is possible to increase the thickness of the metal housing, but it is necessary to optically couple to the optical fiber 412 by the second lens 411, and there is a problem that the entire optical system becomes large.

This is because a two-lens system is employed for the optical system. By increasing the number of necessary members, a small-sized and low-cost semiconductor laser module with a built-in optical isolator can be constructed. It will be difficult. Therefore, it is apparent that an increase in the distance from the semiconductor laser element as the light source to the tip of the optical fiber as the focal point makes it difficult to provide a stable optical system for a long time.

SUMMARY OF THE INVENTION An object of the present invention is to solve such a problem and to improve the long-term reliability of an optical system, to provide the optical system at a small size and at a low cost, and to reduce the number of members to reduce the number of optical components. An object of the present invention is to provide a semiconductor laser module device in which productivity is markedly improved by simplifying axis adjustment.

[0022]

To achieve the above object, a semiconductor laser module device according to the present invention has a metal stem, a condenser lens and an optical isolator, and a first metal holder. Wherein the metal stem holds the semiconductor laser, the focusing lens focuses the light emitted from the semiconductor laser on the optical fiber, and the optical isolator reflects the light reflected from the optical fiber. The first metal holder has a cylindrical shape, and a condensing lens and an optical isolator are integrally incorporated therein, and the first metal holder has a diameter limited to an inner side from the cut of the outer periphery of the metal stem. Inside, the thickness of the opening edge is increased.

Further, the metal holder has a second metal holder, and the second metal holder has a cylindrical shape, houses the semiconductor laser therein, and is limited to an inside of a notch on the outer periphery of the metal stem. The thickness of the opening edge is increased within the radius and fixed to the metal holder, and the first metal holder is fixed to the opening edge of the second metal holder.

The metal holder and the metal stem are fixed by resistance welding.

After the second metal holder is fixed, a screening test and a characteristic selection are performed on the semiconductor laser.

[0026]

In the present invention, a lens for condensing output light from a semiconductor laser and an optical isolator for removing the influence of reflected return light are fixed to the same metal holder, and then fixed to a metal stem on which the semiconductor laser is mounted. By doing
Since a metal holder having a large thickness for fixing to a metal stem can be fixed by welding while avoiding a cutout portion of the metal stem, a small and highly reliable semiconductor laser module is configured with a minimum number of members. be able to.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 is a sectional view showing a non-temperature-controlled semiconductor laser module having a built-in optical isolator according to Embodiment 1 of the present invention.

In the figure, a semiconductor laser module device according to the first embodiment of the present invention
, A metal stem 12, a condenser lens 13, a first metal holder 15, and an optical isolator 18.

The semiconductor laser device 11 includes a metal stem 12
Is fused by solder through a heat sink 111. A monitoring photodiode is attached to the metal stem 12.

The first metal holder 15 has a cylindrical shape, and is provided with an annular support portion 15a protruding in the inner diameter direction on an inner peripheral surface near the metal stem 12 side.
The metal holder 15 has an inner space partitioned into two front and rear chambers 15b and 15c with a support part 15a as a boundary.

The condensing lens 13 includes the first metal holder 1
5, the optical isolator 18
Is housed in the front chamber 15b of the first metal holder 15, and the condenser lens 13 and the optical isolator 18 are provided on the first metal holder 15 with their optical axes aligned.

The first metal holder 15 has a rear chamber 15c.
The semiconductor laser element 11 is accommodated therein, the thick portion 15d of the opening edge thereof is brought into contact with the metal stem 12, and the first metal holder 15 and the metal stem 12 are fixed by resistance welding. The first metal holder 15 hermetically seals the semiconductor laser element 11 while being fixed to the metal stem 12.

After the output light from the semiconductor laser element 11 passes through the optical isolator 18 by the condenser lens 13 and is adjusted with the optical fiber 17, the optical fiber 1
7 is held in the first metal holder 1
5 is fixed by YAG welding.

In the present embodiment, the condensing lens 13
And the optical isolator 18 are fixed to the first metal holder 15, so that the outer shape of the metal stem 12 and the range of the holder diameter R limited to the inside of the notch 12a formed in the metal stem 12 for automatic recognition. Inside, the thick portion 15d of the metal holder 15 can be configured to have a large thickness ensuring sufficient strength, and the optical system can be stabilized for a long time.

Also, it is difficult to ensure accurate fixed position accuracy.
Resistance welding between the metal holder 15 and the metal stem 12 can be easily performed while avoiding the notch 12a of the metal stem 12, and occurs between the metal holder 15 and the notch 12a of the metal stem 12. Abnormal melting can be suppressed.

Therefore, in the non-temperature-controlled semiconductor laser module device having a built-in optical isolator according to the present invention, by fixing the condenser lens 13 and the optical isolator 18 to the same metal holder 15, good resistance welding and long-term operation can be achieved. It is possible to secure a stable optical coupling system. Also, in the present invention, a single lens system of a light condensing system is adopted for optical coupling of the semiconductor laser, and the number of members is minimized, and a small-sized and low-cost device which greatly improves productivity. It is possible to configure a semiconductor laser module with a built-in optical isolator.

(Embodiment 2) FIG. 2 is a sectional view showing a non-temperature-adjustable semiconductor laser module having a built-in optical isolator according to Embodiment 2 of the present invention.

In the second embodiment, the semiconductor laser element 11 is fused to a solder via a heat sink 111 on a metal stem 12 on which a monitoring photodiode is mounted, and the semiconductor laser element 11 is placed in a cylindrical second metal holder 25. And the heat sink 111 is resistance-welded.

A typical example of a semiconductor laser device which is easily affected by reflected return light and is suitable as an embodiment of the present invention is D.
Although the FB-LD is mentioned, the operation in the stable dynamic single-axis mode is indispensable in the DFB-LD. Therefore, the selection process performed on each semiconductor laser element is also diversified, and the failure judgment criterion is set to FP. -Stricter than LD. Therefore, the yield of non-defective products in each process is relatively low. In the screening and characteristic selection in a state where the condensing lens and the optical isolator are fixed as in the first embodiment, the production cost is reduced. Is difficult.

The second embodiment is a means for solving such a problem. In the second embodiment, screening and characteristic selection are performed on the semiconductor laser element 11 with the second metal holder 25 fixed.

In this embodiment, the second bonding wire for protecting the bonding wire for electrically connecting the semiconductor laser element 11 and the metal stem 12 and the semiconductor laser element itself from an erroneous handling in the screening / characteristic selection step are prevented. Is characterized by having the metal holder 25 described above. Semiconductor laser device 1 that has completed screening and characteristic selection with second metal holder 25 fixed.
1 is that, after welding and fixing a first metal holder 15 to which the condenser lens 13 and the optical isolator 18 are fixed, the output light passes through the condenser lens 13 and the optical isolator 18 and is optically coupled to the optical fiber 17. Is done. Also in the present embodiment, the first metal holder 15 and the optical fiber 17 are configured such that the optical axis is adjusted via the metal sleeve 117 and then fixed by YAG welding.

In the second embodiment, in particular, the screening and characteristic selection of the semiconductor laser device 11 can be performed in a state of small added value. In addition to various effects, in resistance welding between the metal stem 12 and the second metal holder 25, it is easy to remove metal chips that may be generated during resistance welding such as slight abnormal melting by a PIND test, It is possible to further improve the quality of the non-temperature-controlled semiconductor laser module having the built-in optical isolator.

[0044]

As described above, according to the present invention, since the condensing lens and the optical isolator are integrally mounted on the metal holder, a sufficient strength is secured within the limited range of the metal holder diameter. A thick metal holder can be configured, and long-term stabilization of the optical system can be achieved.

In addition, resistance welding between the metal holder and the metal stem, for which it is difficult to secure accurate fixing position accuracy, can be easily performed while avoiding the notch of the metal stem. Can be suppressed from being abnormally melted.

Therefore, a good resistance welding and a long-term stable optical coupling system can be ensured, and a small and low-cost built-in optical isolator with high productivity and a minimum number of members by employing a single lens system. A semiconductor laser module can be configured.

In addition, the screening and characteristic selection of the semiconductor laser element can be performed in a small value-added state, and the cost can be further reduced. In addition, in the resistance welding between the metal stem and the second metal holder, Metal debris that may occur during resistance welding, such as slight abnormal melting, can be easily removed by a PIND test, and the quality of the configured non-temperature-controlled semiconductor laser module with a built-in optical isolator can be further improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a non-temperature-controlled semiconductor laser module with a built-in optical isolator according to Embodiment 1 of the present invention.

FIG. 2 is a cross-sectional view showing a non-temperature-controlled semiconductor laser module with a built-in optical isolator according to a second embodiment of the present invention.

FIG. 3 is a sectional view showing a conventional coaxial semiconductor laser module with a built-in optical isolator.

FIG. 4 is a cross-sectional view showing a conventional non-temperature-controlled semiconductor laser module in which a lens for forming a parallel beam and an optical isolator are fixed to the same metal housing.

[Explanation of symbols]

 Reference Signs List 11 semiconductor laser element 12 metal stem 13 condenser lens 15 first metal holder 18 optical isolator 25 second metal holder

Claims (4)

[Claims] 1. A semiconductor laser module device having a metal stem, a condenser lens and an optical isolator, and a first metal holder, wherein the metal stem holds a semiconductor laser, and the condenser lens is An optical fiber for converging light emitted from the semiconductor laser to an optical fiber, an optical isolator for removing the influence of the reflected light returned from the optical fiber on the semiconductor laser, and a first metal holder having a cylindrical shape. Wherein a condensing lens and an optical isolator are integrally incorporated therein, and the thickness of the opening edge is increased within a diameter limited to the inside of the outer periphery of the metal stem. apparatus. 2. The metal holder has a second metal holder. The second metal holder has a cylindrical shape, houses the semiconductor laser therein, and is limited to an inside of a notch on an outer periphery of a metal stem. The thickness of the opening edge is increased within a predetermined diameter and is fixed to a metal holder, and the first metal holder is fixed to the opening edge of a second metal holder. 2. The semiconductor laser module device according to 1. 3. The semiconductor laser module device according to claim 1, wherein the metal holder and the metal stem are fixed by resistance welding. 4. The semiconductor laser module device according to claim 2, wherein after the second metal holder is fixed, a screening test and a characteristic selection are performed on the semiconductor laser.