JP3698967B2 - Semiconductor laser module - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a semiconductor laser module used for, for example, optical communication and optical information processing, and more specifically, a semiconductor laser module in which a light beam emitted from a semiconductor laser whose temperature is adjusted by a cooling element is coupled to an optical fiber. About.
[0002]
[Prior art]
Semiconductor laser modules are widely used as signal light sources used in optical fiber transmission devices and the like. Miniaturization of transmission devices using optical fibers is progressing, and high integration of circuit boards is required. At the same time, various components incorporated in the circuit board are reduced in size and height. In relation to such components, the semiconductor laser module is particularly required to be thin.
[0003]
FIG. 2 shows the structure of a conventional semiconductor laser module. One end of an optical fiber 12 for transmitting an optical signal is accommodated in one side wall of the module package 11 of the semiconductor laser module 10. An electronic cooling element 13 is disposed on the inner bottom surface of the module package 11, and a semiconductor laser 15 and a light beam emitted therefrom are optically coupled to the optical fiber 12 via the substrate 14 thereon. A lens 16 is arranged.
[0004]
In the semiconductor laser module 10, the following measures are taken in order to reduce the height of the module package 11 as much as possible. The thickness of the electronic cooling element 13 is minimized in order to exhibit the required cooling capacity. The substrate 14 disposed thereon is processed so that the portion on which the lens 16 is placed is as thin as possible. Since the height of the portion on which the semiconductor laser 15 is placed is set so that the optical axis of the lens 16 and the laser beam coincide with each other, this portion needs a certain thickness (height). The smaller the diameter of the lens 16, the lower the height of the module package 11. In practice, however, it is necessary to ensure a predetermined opening angle (NA), and the lens 16 is set to the smallest aperture that satisfies this requirement. Yes.
[0005]
[Problems to be solved by the invention]
As described above, in the structure of the conventional semiconductor laser module, the thickness of the portion of the substrate 14 on which the lens 16 is placed is made as thin as possible in order to minimize the height of the entire internal components. However, the total height of the electronic cooling element 13 and the various components (chip-on-carrier) such as the substrate 14 and the semiconductor laser 15 mounted thereon is limited by the thickness of the substrate 14 in processing. However, it is logically impossible to make it lower than the value obtained by adding the diameter of the lens 16 to the height of the electronic cooling element 13.
[0006]
Accordingly, an object of the present invention is to provide a semiconductor laser module capable of reducing the overall height occupied by these components in the package by devising the arrangement of the components.
[0007]
Another object of the present invention is to provide a semiconductor laser module capable of reducing the height of the entire component in the package below the value obtained by adding the lens diameter to the height of the cooling element.
[0008]
[Means for Solving the Problems]
In the present invention, (b) a module package, (b) a thermally conductive substrate having a planar upper step and a lower step with a stepped portion as a boundary, and (c) a lower surface fixed to the inner bottom surface of the module package. A temperature adjusting element for temperature adjustment whose upper surface is fixed to the lower surface of the upper stage of the substrate, (d) a semiconductor laser disposed on the substrate, (e) an optical fiber, and (f) a lower step of the substrate. A semiconductor laser module is provided with a lens that is fixed and optically couples the semiconductor laser and the optical fiber.
[0009]
That is, in the present invention, the substrate disposed on the temperature adjusting element such as a Peltier element for adjusting the temperature is composed of an upper part, a lower part and a step part connecting them, and the lower surface of the upper part is formed. It fixes to the upper surface of a temperature control element. As a result, the lower part is arranged at a lower position than the upper part by the step part, and if the semiconductor laser is arranged in the upper part and the lens is fixed to the lower part, the bottom from the module package to the upper end of the lens. It becomes possible to make height lower than before.
[0010]
Further, the present invention is characterized in that the lower step portion of the substrate is disposed closer to the inner bottom surface of the module package than the upper step portion by the step portion. If the step is made relatively large, the position of the lower step portion of the substrate can be made lower. As a result, the height can be reliably reduced as compared with the conventional semiconductor laser module. Of course, the upper surface of the lower part of the substrate does not necessarily need to be lower than the upper surface of the temperature adjustment element.
[0011]
Further, the present invention is characterized in that the lower surface of the lower step portion of the substrate is arranged in a non-contact state with a predetermined distance from the inner bottom surface of the module package. As a result, heat is not directly conducted between the substrate and the module package, the thermal energy can be effectively utilized, and the temperature adjusting element can be downsized.
[0013]
In the invention according to claim 4 , the semiconductor laser module includes: (a) a module package having a predetermined shape; (b) a semiconductor laser that emits laser light; (c) a temperature adjustment element for temperature adjustment; ) Having first and second surfaces with the bent portion as a boundary, the temperature adjustment element is fixed to the first surface , and the first surface is based on the bottom surface of the module package , It is characterized by being at a position farther from the second surface fixing the lens .
[0018]
In the present invention, the temperature adjusting element is an electronic cooling element for electronically cooling the semiconductor laser.
[0019]
In the present invention, the temperature adjustment element is an electronic cooling element for electronically cooling the semiconductor laser. Of course, it is also possible to arrange not only the cooling element but also the heating element as necessary or separately.
[0020]
【Example】
Hereinafter, the present invention will be described in detail with reference to examples.
[0021]
FIG. 1 shows the structure of a semiconductor laser module according to an embodiment of the present invention. The semiconductor laser module 20 of the present embodiment uses a slightly elongated module package 21. On one side wall, the vicinity of one end of the optical fiber 22 for transmitting an optical signal is YAG-fixed. An electronic cooling element 23 made of a Peltier element is fixed to the inner bottom surface of the module package 21 with solder. On the upper surface of the electronic cooling element 23, an upper stage portion 24U made of a metal plate having a predetermined level h and having two levels is fixed by solder. A semiconductor laser 25 is fixed to the end of the upper stage portion 24U that is close to the optical fiber 22 by soldering. The fixing position of the optical fiber 22 is set in advance so that the optical axis thereof coincides with the height of the emitting portion of the semiconductor laser 25. A lens 26 is YAG-fixed on the upper surface of the lower portion (crank portion) 24D of the substrate. The step h of the substrate 24 is set to a value such that the optical axis of the lens 26 and the optical fiber 22 coincide. The lower surface of the lower portion 24D of the substrate is not in contact with the inner bottom surface of the module package 21.
[0022]
In the semiconductor laser module 20 having such a configuration, the semiconductor laser 25 and the optical fiber 22 are optically coupled by the lens 26. The semiconductor laser 25 is radiated by the electronic cooling element 23 through the substrate 24, and is maintained in a desired temperature range.
[0023]
Moreover, in the semiconductor laser module 20 of the present embodiment, the step 24 is provided on the substrate 24, and the height of the upper surface of the lower portion 24D can be made lower than the height of the upper surface of the electronic cooling element 23. Therefore, the height of the entire component in the module package 20 is smaller than the value obtained by simply adding the height of the electronic cooling element 23 and the thickness of the substrate 24 to the height of the lens 26, as well as the electronic cooling element 23. Depending on the height and the set value of the level difference h, the overall height can be significantly lower than a value obtained by simply adding the height of the electronic cooling element 23 and the aperture of the lens 26. Therefore, the degree of freedom in selecting various components such as the electronic cooling element 23 is increased, and a margin can be provided in terms of performance and component reliability. Of course, the height of the semiconductor laser module can be greatly improved by setting the heights of various components to the limit values.
[0024]
In the embodiment, one semiconductor laser is arranged in the semiconductor laser module. However, for example, a semiconductor laser module in which two or more semiconductor lasers are arranged as disclosed in Japanese Patent Laid-Open No. 5-281442. The present invention can be applied.
[0025]
In the embodiment, an example of the lower part of the substrate is shown. However, various shapes, positions and heights of various parts (chip-on-carriers) arranged on the temperature adjusting element are selected according to the shape and size of the various parts (chip-on-carrier). It is possible to deform.
[0026]
【The invention's effect】
As described above, according to the present invention, the substrate disposed on the temperature adjustment element has an upper part, a lower part, and a step part connecting them, and the lower surface of the upper part is the temperature adjustment element. It was made to fix to the upper surface. As a result, the lower part is arranged at a position lower than the upper part by the level difference, and if the semiconductor laser is arranged on the upper part and the lens is fixed to the lower part, the bottom of the module package is extended to the upper end of the lens. It becomes possible to reduce the height of the. Therefore, it is possible to reduce the height of the semiconductor laser module while giving some margin to the performance and size of each component, thereby contributing to economy and downsizing of the transmission device. Further, downsizing of the individual component parts can further promote the downsizing of the semiconductor laser module.
[0027]
Further , according to the present invention, the position of the lower step portion of the substrate can be made lower by taking a relatively large step, and the thickness of the substrate is fixed to the portion where the lens is fixed and the semiconductor laser as in the prior art. There is no need to make a difference in the fixed part. Therefore, there is an advantage that the processing of the substrate becomes easy by simply bending the flat plate, for example.
[0028]
Further, according to the present invention, the lower surface of the lower portion of the substrate is in a non-contact state with a predetermined distance from the inner bottom surface of the module package. For this reason, heat is not directly conducted between the substrate and the module package, the thermal energy can be effectively utilized, and the temperature adjusting element can be made compact.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing the structure of a semiconductor laser module according to an embodiment of the present invention.
FIG. 2 is a schematic configuration diagram showing the structure of a conventional semiconductor laser module.
[Explanation of symbols]
20 Semiconductor Laser Module 21 Module Package 22 Optical Fiber 23 Electronic Cooling Element 24 Substrate 24U Upper Part 24D Lower Part 25 Semiconductor Laser 26 Lens h Step

Claims (3)

Module package,
A thermally conductive substrate having a planar upper and lower steps with the stepped portion as a boundary;
A temperature adjustment element for temperature adjustment, the lower surface of which is fixed to the inner bottom surface of the module package, and the upper surface of which is fixed to the lower surface of the upper portion of the substrate;
A semiconductor laser disposed on the upper stage of the substrate;
Optical fiber,
A lens that is fixed to the upper surface of the lower part of the substrate and optically couples the semiconductor laser and the optical fiber;
The semiconductor laser module according to claim 1 , wherein a surface of the substrate on which the lens is fixed is closer to an inner bottom surface of the module package than an upper surface of the temperature adjusting element. 2. The semiconductor laser module according to claim 1, wherein the lower surface of the lower part of the substrate is disposed in a non-contact state with a predetermined distance from the inner bottom surface of the module package. 2. The semiconductor laser module according to claim 1, wherein the temperature adjusting element is an electronic cooling element for electronically cooling the semiconductor laser.

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