JPH07168040A - Semiconductor laser focusing device - Google Patents

Abstract

PURPOSE:To effectively heighten the light emitting density from a laser having a plurality of light emitting sources or a plurality of semiconductor lasers having one light emitting source. CONSTITUTION:Either a semiconductor laser 1a having a plurality of light emitting sources or a plurality of semiconductor lasers having one light emitting source is combined with a light wave guide in the way the light rays emitted from respective light emitting sources are optically combined with respective input ports of the light wave guide, wherein the light wave guide is so composed as to have the input ports in the same number as that of the light emitting sources in one end face and only one output port in the other end face to which all the emitted light rays are joined.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser focusing device. The present invention more particularly relates to a means for effectively increasing the light density of a semiconductor laser having a plurality of light emitting sources.

[0002]

2. Description of the Related Art A semiconductor laser is the smallest laser and has a high oscillation efficiency of over 50%, and has a high industrial utility value. In recent years, it has been playing an important role mainly in the field of information processing industry such as CD, optical disk or optical communication. However, semiconductor lasers have not been used at all in the field of processing, which is an application field of lasers for a long time. It is true that a semiconductor laser is highly efficient, but the size of one light source is 1 mm or less at most even for large ones, and the light output emitted from it is limited, so a semiconductor with one light source This is due to the fact that the laser alone can output only a few watts at most. However, since the semiconductor laser has a very high oscillation efficiency as described above, it is certain that it has potential as a high-output light source. With the recent progress in the room temperature high power operation technology of semiconductor lasers, semiconductor lasers have attracted attention as excitation sources for solid-state lasers, and technology for obtaining even higher optical output from semiconductor lasers has been developed. For this purpose, many semiconductor laser manufacturers take a method of obtaining a large amount of light output from one device by increasing the number of light emitting sources by adopting a structure in which a plurality of semiconductor lasers are arranged one-dimensionally or two-dimensionally. There is. However, the laser light emitted from such a device has poor coherence because each light emitting source oscillates completely independently. That is, it cannot be regarded as a laser beam having one large light output. Therefore, the important advantage of the laser beam, namely the ability to focus on a single point and the consequent possibility of processing an object by achieving a high energy density, is lost. For this reason, those skilled in the art who are required to improve the light density as much as possible in order to apply such a high-power semiconductor laser to processing or increase the efficiency of solid-state laser excitation, emit each light individually. It is necessary to develop a technique for condensing a plurality of emitted lights from a plurality of light emitting sources which are nothing but linear light sources or planar light sources into a spot as small as possible. Bayer, etc. collectively collects the emitted light from a laser diode array in which multiple semiconductor lasers are arranged one-dimensionally by a fiber lens arranged in parallel with the array in the direction perpendicular to the array, and collects each light. A method was devised in which all the optical fibers are optically coupled to each other at each point, and all these optical fibers are bundled at the other end to form a pseudo single light source (see Japanese Patent Laid-Open No. 5-93828). However, according to this method, the larger the number of light emitting sources constituting the laser diode array, the larger the bundle of optical fibers, which causes a great difficulty in converging light at one point.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is directed to a semiconductor laser having a plurality of light emitting sources each of which emits light independently and is merely a linear light source or a planar light source. An apparatus for effectively increasing the light density of a plurality of outgoing lights.

[0004]

In order to solve the above problems, in the present invention, a semiconductor laser having a plurality of light emitting sources or a plurality of semiconductor lasers having a single light emitting source, and the light emitting source on one end face are provided. An optical waveguide having the same number of input ports and made so that all of them join together toward one output port provided on the other end face, and the light emitted from each of the light emission sources is of the optical waveguide. The present invention provides a semiconductor laser device characterized by being combined so as to be optically coupled to each of the input ports. Further, the optical coupling between the semiconductor laser and the optical waveguide may be through an optical fiber.

[0005]

The basic concept of the present invention will now be described. The inventors have studied and studied how to condense light emitted from a semiconductor laser having a plurality of light emission sources into a spot as small as possible, and as a result, a waveguide like an optical branch formed in an optical waveguide. It has been found that this object can be effectively achieved by using the structure in the reverse direction.
Here, the optical branching device typically has a waveguide structure as shown in FIG. The waveguide shown by the shaded area in FIG. 4 has a refractive index larger than that of the substrate in the peripheral portion, and the light passing through the waveguide is confined in the waveguide by total reflection and propagates. Optical splitters are commonly used to distribute an optical signal from one signal source to multiple optical fibers. That is, in the optical branching device, one input port branches into a plurality of waveguides from the middle and is divided into a plurality of output ports. An example of the optical branching device shown in FIG. 4 is to branch from one input port to four output ports. When the optical branching device made in such a shape is used in the reverse direction, a large number of tributaries are gathered and a plurality of waveguides are converged into one in a fashion that creates a main stream. That is, if the emitted light from each light emitting source of the semiconductor laser having a plurality of light emitting sources is input from each output port, the light density can be effectively increased at the input port. As a matter of course, the waveguide forming the optical branching device must be made of a material that does not absorb light at the wavelength of the semiconductor laser that passes through it. Otherwise, the heat from the waveguides will cause destruction at the input port where they merge. Now, let's move on to the problem of how to input the emitted light from each light emitting source to the optical branching device. There are two ways to do this. One is a method of optically coupling by a butt coupling or a lens. For this purpose, the positional relationship between each light emitting source and each output port of the corresponding optical branching device must be mechanically determined with extremely good accuracy. This is quite difficult with normal machining, but since the optical waveguide manufacturing technology is based on lithography, it is possible to create waveguides with very good reproducibility and high precision. Therefore, alignment with a one-dimensional array type semiconductor laser which is also formed by lithography can be achieved relatively easily. In the case of a semiconductor laser in which a plurality of elements are two-dimensionally stacked, the optical coupler can be similarly stacked. The other is a method in which light emitted from a plurality of semiconductor lasers is once guided to an optical fiber and is optically coupled to one of the output ports of the optical coupler. Optically coupling each light-emitting element to an optical fiber is quite a laborious task, but for example, in the case of a one-dimensional array type semiconductor laser, alignment is performed using V-grooves etc. made by anisotropic etching of silicon. If you do, it is relatively efficient. This method is also useful when there are multiple semiconductor lasers that function alone.

By doing so, it is possible to effectively increase the light density of a plurality of emitted lights of a semiconductor laser having a plurality of light emitting sources each of which emits light separately and is only a linear light source or a planar light source. .

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic perspective view showing the configuration of an apparatus for converging a single semiconductor laser having a plurality of light emission sources in the first embodiment to which the present invention is applied. The semiconductor laser 1a in this embodiment has a plurality of light emitting sources arranged one-dimensionally at equal intervals.
The distance between these light emitting sources is 500 μm. Material is GaAlAs
And oscillates near 860 nm. The optical branching device 2a in this embodiment is composed of an optical waveguide having a refractive index higher than that of the surroundings by Ti diffusion on a LiNbO3 substrate which does not absorb at this wavelength. The optical coupling between the semiconductor laser 1a and the optical branching device 2a is based on a butt coupling in which they are butted. The light emitted from each light emitting source of the semiconductor laser is directly optically coupled to the abutted waveguide. After that, they merge with the adjacent waveguides one by one at a gentle angle to finally become one. In this way, the light densities of a plurality of emitted lights of the semiconductor laser having a plurality of light emitting sources, which emit light separately and are merely linear light sources, are effectively increased.
Those skilled in the art will recognize that if the emitted light is condensed by a lens or guided to an optical fiber, it becomes a light source useful as a single high-power semiconductor laser beam for processing.

FIG. 2 is a schematic view showing a second embodiment to which the present invention is applied. The semiconductor laser 1b in the present embodiment is one in which a plurality of light emitting sources are one-dimensionally arranged at equal intervals and are further two-dimensionally laminated. The vertical light source spacing is 1 mm. The optical branching devices 2b ₁ and 2b ₂ were prepared in two stages, a horizontal direction and a vertical direction. Semiconductor laser 1
The materials of b and the optical branching devices 2b ₁ and 2b ₂ are the same as those in the first embodiment. Semiconductor laser 1b and optical splitter 2b ₁ ,
Optical coupling with 2b ₂ is based on butt coupling.
First, the horizontal direction is converged. The optical branching device for converging in the horizontal direction is the same as that of the first embodiment when looking at one horizontal row, and these are vertically stacked by the number of stacked semiconductor lasers 1b. At the exit of each optical branching device, the light beams in the respective lateral directions are converged, and the light beams converged in the lateral direction are lined up in a line in the longitudinal direction as a whole. Next, an optical branching device for vertical focusing is arranged in accordance with the convergent light aligned in a vertical line to perform vertical focusing. In this way, the light densities of a plurality of emitted lights of a semiconductor laser having a plurality of light emitting sources, which emit light separately and are merely planar light sources, are effectively increased. It is also possible to reverse the order of convergence in the vertical direction and the horizontal direction by slightly changing the interval pitch of the waveguides at the entrance.

FIG. 3 is a schematic diagram showing a third embodiment to which the present invention is applied. The semiconductor laser 1c in this embodiment has one light emitting source, and there are a plurality of light emitting sources.
The material of the semiconductor laser 1c is the same as that of the first embodiment. The optical branching device 2c is formed by forming a silica glass waveguide on a silicon substrate. Light emitted from each semiconductor laser 1c is butt-coupled to one end of the optical fiber 3. The other end of each optical fiber 3 is optically coupled to one of the entrances of the optical branching device 2c by a lens group 4 in which distributed index type microlenses are arranged at the same interval pitch as the entrance pitch of the optical branching device 2c. Has been done.
After that, as in the first embodiment, all the lights guided to the respective waveguides are converged into one.

[0010]

As is apparent from the above description, according to the device for condensing light from a plurality of light emitting sources at one point according to the present invention, a semiconductor laser having a plurality of light emitting sources or one light emitting source is provided. It is possible to effectively increase the light density of the emitted light from the plurality of semiconductor lasers having

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a configuration of an apparatus for focusing a semiconductor laser having a plurality of light emitting sources on one point in a first embodiment to which the present invention is applied.

FIG. 2 is a perspective schematic view showing a configuration of a second embodiment to which the present invention is applied.

FIG. 3 is a perspective schematic view showing a configuration of a third embodiment to which the present invention is applied.

FIG. 4 is an explanatory diagram of an optical branching device.

[Explanation of symbols]

1a, 1b, 1c Semiconductor lasers 2a, 2b ₁ , 2b ₂ , 2c Optical splitter 3 Optical fiber 4 Micro lens group

Front Page Continuation (72) Inventor Kenji Ueda 5-10-1, Fuchinobe, Sagamihara-shi, Kanagawa Nippon Steel Corporation Electronics Research Laboratory

Claims (2)

[Claims] 1. A semiconductor laser having a plurality of light emitting sources or a plurality of semiconductor lasers having a single light emitting source, and one end face having the same number of input ports as the light emitting sources and the only one provided on the other end face. Optical waveguides that are all made to merge towards one output port, such that the light emitted from each of the light emitting sources is optically coupled to each of the input ports of the optical waveguides. A semiconductor laser condensing device characterized in that 2. The semiconductor laser condensing device according to claim 1, wherein the optical coupling between the light emitting source and the optical waveguide is through an optical fiber.