JPH09116224A - Flat type semiconductor laser module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the height of a flat type semiconductor laser module so as to reduce the space occupied by the module. SOLUTION: In a flat type semiconductor laser module provided with a semiconductor laser 14 which emits laser light, an optical fiber 17, a lens 15 which condenses the light emitted from the laser 14 into a beam and couples the beam to the core of the fiber 17, and a flat type package which houses the laser 14 and lens 15, the core of the fiber 17 is positioned to a level lower than that of the laser light emitting point of the laser 14 by using the bottom face of the package 11 as a reference. To be concrete, the light emitted from the laser 14 is condensed into a beam through the lens 15 and, at the same time, the condensed beam is directed downward. The end face of the fiber 17 is cut obliquely against the center line of the fiber 17 so that the normal line to the end face can be directed downward. In another constitution of the laser module, two lenses of a lens which condenses the light into a beam and another lens which is positioned to a level lower than that of the condenser lens, further condenses the beam, and couples the condensed beam to an optical fiber are provided.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat type semiconductor laser module used for optical communication and optical measurement, and more particularly to a flat type semiconductor laser module suitable for saving mounting space in the height direction.

[0001]

2. Description of the Related Art Semiconductor laser modules are used to convert electrical signals into optical signals in optical fiber transmission systems and the like. By applying a modulated current signal to the semiconductor laser diode arranged in the semiconductor laser module, electro-optical conversion is performed and an optical signal is output. As such a semiconductor module, a flat-type semiconductor laser module using a flat-type package is widely used because of demands for performance improvement such as high-speed modulation and ease of mounting on a panel.

An example of a flat type semiconductor laser module is disclosed in Japanese Patent Application No. 5-169963. FIG. 3 is a vertical sectional view showing an example of a conventional flat type semiconductor laser module as described in the above patent publication.

Inside the flat type package 31,
A carrier 33 having the electronic cooling element 32 sandwiched therebetween is mounted. A semiconductor laser diode 34 and a lens 35 for collecting the light emitted from the semiconductor laser diode 34 and optically coupling it to an optical fiber 37 are arranged on the carrier 33.

[0004]

The flat semiconductor laser module is mounted on the electric circuit panel with its bottom faced, and the electric terminals in the package are fixed to the pads and the like of the electric circuit panel by soldering. The panel on which the flat semiconductor laser module is mounted in this way is
They are arranged close to each other in the rack.

In recent years, the racks have been arranged close to each other with a high density because of the demand for downsizing of the apparatus itself. However,
Since the height of the semiconductor laser module is high in the arrangement space of the rack as compared with other electric circuit components, the semiconductor laser module is often a limiting factor. There is a strong demand for thinning of the semiconductor laser module, and there is also a demand for reducing the width of one sheet. In the conventional flat type semiconductor laser module, the lens 3 is arranged so that the emitted light 38 from the semiconductor laser 34 is substantially horizontal to the bottom surface of the package.
The height of the central axis of 5 is made to coincide with the emission position of the semiconductor laser diode 34. On the other hand, since the semiconductor laser diode 34 is arranged on the electronic cooling element 32 as described above, it is arranged at a high position inside the package.

If the light emitted from the semiconductor laser diode 34 is collected while being kept horizontal and is coupled to the optical fiber, the position of the optical fiber naturally rises. Moreover, although the optical fiber itself has a small diameter, a space for the optical fiber fixing portion 36 is required to fix the optical fiber to the package. Therefore, including the part required for fixing the optical fiber, the entire semiconductor laser module becomes very expensive.

In view of the above-mentioned drawbacks, it is an object of the present invention to provide a flat type semiconductor laser module which is particularly low in height and contributes to space saving.

[0008]

In order to eliminate the above-mentioned drawbacks of the conventional semiconductor laser module, and particularly to reduce the height, a semiconductor laser diode for emitting light, an optical fiber, and the emitted light are condensed. In a flat type semiconductor laser module equipped with a lens that is optically coupled to the core of an optical fiber, a semiconductor laser diode, and a flat type package that accommodates the lens, the core is located at the emission point of the emitted light with respect to the bottom surface of the package. Also try to be in a low position.

Further, a semiconductor laser diode for emitting light, an optical fiber, a flat type package for housing the semiconductor laser diode, the position of the emitted light is lowered to a lower position with reference to the bottom surface of the package, and
It is characterized by comprising a condensing means for condensing and optically coupling with the core of the optical fiber.

Here, the light collecting means includes a first light collecting means for collecting the emitted light from the semiconductor laser diode and for directing the emitted light downward with reference to the bottom surface of the package. The end face of the optical fiber is formed obliquely with respect to the center line of the optical fiber,
It is characterized in that the end face is arranged so that the normal direction is downward.

The first light condensing means is a lens arranged at a position lower than the semiconductor laser diode with reference to the bottom surface of the package. This lens may be a lens having a convex shape or a gradient index lens.

In addition to the above structure, the flat type semiconductor laser module of the present invention comprises a first condensing means for condensing the light emitted from the semiconductor laser diode and outputting a first converging beam, and a package. It includes a second condensing unit which is arranged at a position lower than the first condensing unit with respect to the bottom surface and which condenses the first condensed beam and outputs the second condensed beam. . The first light converging unit and the second light condensing unit are characterized by being a lens having a convex shape or a gradient index lens.

[0013]

Next, a semiconductor laser module according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a vertical sectional view showing a first embodiment of a semiconductor laser module of the present invention. In FIG.
A carrier 13 is housed inside the package 11 with the electronic cooling element 12 sandwiched therebetween. The electronic cooling element 12 is an element for controlling the temperature so that the semiconductor laser diode stably outputs the emitted light of a constant optical output even when the ambient temperature of the semiconductor laser module changes, and is usually a pertier. A device is used.

A semiconductor laser diode 14 and a lens 15 are arranged on the carrier 13.

On the other hand, an optical fiber 17 is fixed to the outside of the package 11 by a fiber fixing portion 16. The light emitted from the semiconductor laser diode 14 is
The light is collected by the lens 15 and optically coupled to the core of the optical fiber 17. Here, the semiconductor laser diode 1
The lens 15 is arranged so that the light emitted from the lens 4 is directed downward. In the conventional semiconductor laser module, the semiconductor laser diode 14 and the lens are arranged so that the heights of the central axes thereof are substantially the same, whereas in the present invention, the lens 15 is arranged so that the emitted light is directed downward. The central axis is designed to be below the emission point of the semiconductor laser diode 14.

By adopting such a configuration, the light emitted from the semiconductor laser diode 14 is focused through the lens 15 and is directed downward, so that the focusing point on the core of the optical fiber 17 is also at the conventional position. Will be lower. If this condensing point is too low, the optical fiber 17 cannot be properly fixed by the optical fiber 16, so the height should be set approximately at the middle of the package. By doing so, the height of the optical fiber fixing portion 16 itself becomes a limiting factor that determines the height of the semiconductor laser module,
It is possible to realize a semiconductor laser module having substantially the same height as the height of the optical fiber fixing portion 16.

In the above structure, if the outgoing light is focused downward and is directly coupled to the horizontally fixed optical fiber, the coupling efficiency is high because the optical axes of both are shifted. It will drop significantly. Therefore, in the semiconductor laser module of the present invention, the end face of the optical fiber 17 is obliquely polished so that the angle of the optical axis of the light incident on the optical fiber 17 matches the angle of the optical axis of the focused beam. Since the focused beam is coupled to the optical fiber 17 from above, the optical fiber 17 is arranged so that the direction normal to the end face is downward.

The lens 15 for collecting the emitted light may be an aspherical lens having a convex shape or the like, or a lens having a distributed refractive index such as a rod lens.

Next, a second embodiment of the semiconductor laser module of the present invention will be described. FIG. 2 is a vertical sectional view showing a second embodiment of the flat type semiconductor laser module of the present invention. In the first embodiment, the coupling system of the semiconductor laser diode 14 and the optical fiber 17 is one of the lenses 15.
It is composed of a single lens system. In contrast, the second
In this embodiment, the optical coupling system includes a two-lens system including a first lens 25a and a second lens 25b.

The light emitted from the semiconductor laser diode 14 is first converted by the first lens 25a into a beam 18 which is downward from the horizontal direction and which is substantially a collimated beam. Further, the beam 18 is converted into focused light by the second lens 25b, and again converted into light traveling in the horizontal direction, and is coupled to the optical fiber 17.

In the present embodiment, the first lens 25a is arranged at a position lower than the emission point of the semiconductor laser diode 14 in order to direct the emitted light downward.
On the other hand, since the second lens needs to return the downward light to the horizontal light again, it is arranged at a position lower than the position of the first lens.

In the second embodiment, two lenses are required, but the light emitted from the semiconductor laser diode 14 is once directed downward, but becomes light that travels in the horizontal direction again, and becomes the optical fiber 17. Therefore, a high coupling efficiency can be obtained without making the end faces oblique as in the first embodiment.

Also in this embodiment, similarly to the first embodiment, a rod lens can be used as the lens in addition to a lens having a convex shape such as an aspherical lens.

[0025]

As described above, in the flat type semiconductor laser module of the present invention, the semiconductor laser diode for emitting light, the optical fiber, and the lens for converging the emitted light and optically coupling them to the core of the optical fiber. In a flat-type semiconductor laser module including a flat-type package that accommodates a semiconductor laser diode and a lens, the core is located at a position lower than the emission point of emitted light with reference to the bottom surface of the package. Therefore, since the position where the optical fiber is fixed can be lowered,
The height of the entire module can be reduced, which contributes to narrowing the array of the panels and eventually to downsizing the entire device.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view showing a first embodiment of a flat type semiconductor laser module of the present invention.

FIG. 2 is a vertical sectional view showing a second embodiment of the flat type semiconductor laser module of the present invention.

FIG. 3 is a vertical cross-sectional view showing an example of a conventional flat type semiconductor laser module.

[Explanation of symbols]

 11 package 12 electronic cooling element 13 carrier 14 semiconductor laser diode 15 lens 16 fiber fixing part 17 optical fiber 18 beam 25a lens 25b lens 31 package 32 electronic cooling element 33 carrier 34 semiconductor laser diode 35 lens 36 fiber fixing part 37 optical fiber 38 beam

Claims (10)

[Claims] 1. A semiconductor laser diode that emits light, an optical fiber, a lens that collects the emitted light and optically couples the emitted light to the core of the optical fiber, and the semiconductor laser diode and the lens are housed. In the flat type semiconductor laser module including the flat type package, the core is located at a position lower than the emission point of the emitted light with reference to the bottom surface of the package. 2. A semiconductor laser diode that emits light, an optical fiber, a flat package that accommodates the semiconductor laser diode, and the position of the emitted light is lowered to a lower position with reference to the bottom surface of the package. A flat-type semiconductor laser module comprising: a light-collecting unit that collects light and optically couples it to the core of the optical fiber. 3. The light condensing unit includes a first light condensing unit that condenses the emitted light from the semiconductor laser diode and directs the emitted light downward with reference to the bottom surface of the package. The flat semiconductor laser module according to claim 2, wherein 4. The end surface of the optical fiber is formed obliquely with respect to the center line of the optical fiber, and the normal line direction of the end surface is arranged downward. The flat type semiconductor laser module according to claim 3. 5. The flat type semiconductor according to claim 4, wherein the first condensing unit is a lens arranged at a position lower than the semiconductor laser diode with respect to the bottom surface of the package. Laser module. , 6. The flat-type semiconductor laser module according to claim 5, wherein the lens is a lens having a convex shape. , 7. The flat semiconductor laser module according to claim 5, wherein the lens is a gradient index lens. , 8. The light condensing unit condenses the light emitted from the semiconductor laser diode to output a first condensing beam; and the bottom face of the package as a reference. A second light condensing unit arranged at a position lower than the second light condensing unit and condensing the first condensed beam to output a second condensed beam. Item 2. A flat semiconductor laser module according to item 2. 9. The flat-type semiconductor laser module according to claim 8, wherein the first condensing unit and the second condensing unit are lenses having a convex shape. 10. The flat type semiconductor laser module according to claim 8, wherein the first condensing unit and the second condensing unit are gradient index lenses.