JPH03180090A - Semiconductor laser module - Google Patents

Abstract

PURPOSE:To improve the electrical characteristics and the long-term reliability of a semiconductor laser module by a method wherein a stem on which a semiconductor laser device is mounted is fitted to a mount-holder and fixed by YAG laser spot welding to provide mechanically stable bonding strength and, further, thermal contact is maintained by low temperature solder applied to the fitting part. CONSTITUTION:A rod lens 3 is soldered to a mount-holder 1 with AuSn solder beforehand. A stem 2 on which a laser diode 4 and a photodiode 5 are mounted is fitted and inserted into the mount-holder 1. The stem 2 is fixed by YAG laser spot welding 6 from the side surface of the mount-holder 1 along the circumference. Then the fitting part is soldered 7. After that, a fiber ferrule 11 is adjusted so as to be positioned at an optimum photocopying position while the laser diode 4 is made to emit a light and the fiber ferrule 11 is fixed to the mount-holder 4 by YAG laser spot welding 6 through a slide ring 12 to unify a coupling optical system. With this constitution, the electrical characteristics and the long-term reliability can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor laser module for optical fiber communication, and particularly to a fixing structure for an optical component and a semiconductor laser element.

[Conventional technology]

In a conventional semiconductor laser module, a stem on which a semiconductor laser element and a photodiode are mounted is fitted into one counterbore of a mount holder, fixed with solder, and connected to an optical fiber provided in the other counterbore through a coupling lens. (See Figure 1) In conventional semiconductor laser modules, the semiconductor laser element and stem are generally fixed using solder. First, the semiconductor laser element is fixed to the heat sink. A high melting point solder is used for fixing the next heat sink to the stem, and a solder with a slightly lower melting point is used to easily attach the last stem to the mount holder. .

[Problem to be solved by the invention]

In the conventional "solder" fixing technology described above, there is a so-called solder creep phenomenon in which solder normally undergoes plastic deformation under certain load conditions even at temperatures well below its melting point. The problem with device fixing technology is that it lacks reliability.

For example, in a coupling system between a semiconductor laser element and a single mode fiber, submicron coupling precision is required for direct bonding, and several micron coupling precision is required for an imaging system using a lens. A to the mount of
When u S n (80/20) solder (melting point 283°C) is used, Pb5n (63/37) solder (melting point 183°C) is used to fix the subcarrier (heat sink) to the stem.
) is a common method for soldering. However, when a storage temperature of 85° C. is required for the module, securing the stability of the optical system with this solder fixing structure causes a solder creep phenomenon, which poses a reliability problem.

[Means to solve the problem]

In the semiconductor laser module of the present invention, a groove is provided on the side surface of the mount holder that fixes the coupling lens in the center, and the stem on which the laser diode and photodiode are mounted is inserted from the end face of the mount holder so that the laser diode and the coupling lens face each other. The stem is fitted onto the inner diameter of the mount holder, first laser welded around the groove on the side of the mount holder, and then the fitting part of the stem and mount holder is fixed by soldering.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIGS. 1(a) and 1(b) are a plan view and a sectional view of a semiconductor laser module showing a first embodiment of the present invention. This embodiment shows a fiber pigtailed semiconductor laser module without a single lens coupling temperature adjustment mechanism. In the figure, 1 is a mount holder, 2 is a stem for mounting a laser diode and a monitor photodiode, 3 is a rod lens, 4 is a laser diode, 5 is a monitor photodiode, 6 is laser spot welding, 7 is solder, and 8 is a stem. D
An IP case, 9 a pedestal, 10 a fiber 11 a ferrule, 12 a slide ring, and 13 a lead terminal.

The rod lens 3 is made of AuS in advance on the mount holder 1.
It is soldered with n solder. The stem 2 carrying the laser diode 4 and photodiode 5 is fitted and inserted into the inner diameter of the mount holder l, YAG laser spot welding is performed 6 on the circumference from the side of the mount holder 1, and after fixing, the fitting part is soldered. Attach.

Next, the fiber ferrule 11 is adjusted to the optimal optical coupling position while the laser diode 4 emits light, and the fiber ferrule 11 is fixed to the mount holder 4 by YAG laser spot welding 6 via the slide ring 12 to integrate the coupling optical system. do.

A semiconductor laser module is completed by incorporating the thus integrated coupling optical system together with a pedestal 9 into a DIP type exterior case 8, connecting terminals 13, and sealing with a cap.

Next, the method of fixing the stem and mount holder, which is an original part of the present invention, will be explained in detail using FIGS. 2(a) and 2(b). The mount holder 1 has a groove on the outer periphery of the fitting part with the stem 2 that leaves enough wall thickness to allow YAG laser spot plug welding, and the stem insertion end has a counterbore larger than the fitting system. It is. After fitting and inserting the stem 2 on which the laser diode 4 and photodiode 5 are mounted from the end face of the mount holder 1, and positioning the laser diode 4 and the rod lens 3 tube in the optical axis direction, the YAG is inserted into the groove of the mount holder 1. Perform laser spot welding on at least 3 points on the circumference to fuse. Next, solder on the ring having a lower melting point than the laser diode mount solder, such as P
B-3N eutectic solder (melting point: 183° C.) is placed and heated with a high frequency heater or hot plate of the mount holder 1 to melt the solder, flow into the fitting portion, and fix.

With such a configuration, the joint strength is increased by laser spot welding, and it is possible to prevent solder creep displacement.

FIG. 3 shows a second embodiment of the present invention, in which the groove width of the mount holder 1 is widened and the nugget diameter of the welding spot is Several points are overlaid so that approximately 172 of the numbers overlap. In this example, by overlapping the YAG laser welding part in the optical axis direction, the welding area against the angular deviation in the optical axis direction of the fitting is increased, and the welding strength is also increased. Therefore, changes in the positional deviation of the fitting are reduced. ,
As a result, there is an advantage that changes in positional deviation between the semiconductor laser element and the coupling lens are reduced.

〔Effect of the invention〕

As explained above, the present invention provides mechanically stable bonding strength by YAG laser spot welding for fixing a stem equipped with a semiconductor laser element, and secures thermal contact with low-temperature solder on the mating surface. This has the effect of providing a semiconductor laser module with excellent electrical characteristics and long-term optical system reliability.

[Brief explanation of drawings]

1(a) and 1(b) are a plan view and a side view of a semiconductor laser module according to a first embodiment of the present invention, and FIG. 2(a),
(b) is an excerpted front view and cross-sectional view of the fixing portion of the mount holder to which the stem on which the semiconductor laser element of the semiconductor laser module of the present invention is mounted and the coupling lens are fixed;
Figures (a) and (b) are a front view and a sectional view of the second embodiment. DESCRIPTION OF SYMBOLS 1... Mount holder, 2... Stem, 3... Rod lens, 4... Laser diode, 5... Monitor photodiode, 6... Laser spot welding, 7
... Solder, 8... DIP case, 9... Pedestal, 1
0...Fiber, 11...Ferrule, 12...
・Slide ring, 13...Lead terminal.

Claims (1)

[Claims] In a semiconductor laser module consisting of a semiconductor laser, a coupling lens, and an optical fiber, a groove is provided on the side surface of a mount holder that fixes the coupling lens in the center, and the stem on which the laser diode and photodiode are mounted is inserted from the end face of the mount holder. The laser diode and the coupling lens are fitted to the inner diameter of the mount holder so as to face each other, and a side groove of the mount holder is laser welded from the periphery in order to fix the stem and the mount holder, and the stem and A semiconductor laser module characterized in that a fitting portion of the mount holder is fixed by soldering.