JP2008124358A - Laser module - Google Patents

Abstract

A laser module capable of outputting high-power light while being small in size is provided.
A laser module includes a plurality of surface-emitting lasers arranged two-dimensionally on the same plane (the surface of a package), and a plurality of surface-emitting lasers. And a plurality of optical fibers 12 in which one end is bundled. The plurality of optical fibers 12 are arranged so that the central axis of each one end thereof overlaps the optical axis of the laser beam emitted from the corresponding surface emitting laser among the plurality of surface emitting lasers 11.
[Selection] Figure 1

Description

  The present invention relates to a laser module, and more particularly, to a laser module that can output high-power light while being small in size by using a plurality of surface emitting lasers.

  Conventionally, an apparatus that emits a high-power laser beam is used for industrial applications such as product processing. For example, as an apparatus for generating a laser beam in the ultraviolet region, a laser that converts infrared light from a solid-state laser excited by a semiconductor laser into a third harmonic in the ultraviolet region, an excimer laser, an Ar laser, and the like are put to practical use. ing.

  However, the excimer laser has a problem that the cost and maintenance cost are high because the apparatus is large. Further, since the wavelength conversion laser that converts infrared light into the third harmonic in the ultraviolet region has very low wavelength conversion efficiency, it is very difficult to obtain a high output. In addition, the Ar laser has a very low electro-optical efficiency of 0.005%.

  In view of this, an optical power combining optical system that condenses light from a plurality of light sources (for example, GaN-based semiconductor lasers) at one place and couples the light to an optical fiber or the like has been proposed. As an application field of such an optical system, product processing (for example, soldering of parts on a circuit board), medical relations, an exposure light source, and the like are assumed.

  For example, Japanese Patent Application Laid-Open No. 2002-202442 (Patent Document 1) discloses a combined laser light source and an exposure apparatus using the combined laser light source.

  FIG. 27 is a diagram illustrating the configuration of a combined laser light source disclosed in Japanese Patent Laid-Open No. 2002-202442 (Patent Document 1).

  Referring to FIG. 27, this combined laser light source includes seven semiconductor lasers LD1 to LD7 arrayed and fixed on heat block 110, and collimator lenses 111 to 111 provided corresponding to semiconductor lasers LD1 to LD7, respectively. 117, one condenser lens 120, and one multimode optical fiber 130. Beams B1 to B7 emitted from the semiconductor lasers LD1 to LD7 are collimated by collimating lenses 111 to 117, respectively. The parallel beams B1 to B7 are collected by the condenser lens 120 and converge on the incident end face of the core 130a of the multimode optical fiber 130.

  The beams B <b> 1 to B <b> 7 that have entered the core 130 a are combined into a single beam B and emitted from the multimode optical fiber 130. Therefore, according to this laser light source, a high-power laser beam can be obtained.

  FIG. 28 is a diagram illustrating another configuration of the combined laser light source disclosed in Japanese Patent Laid-Open No. 2002-202442 (Patent Document 1).

  Referring to FIG. 28, the combined laser light source is composed of five semiconductor lasers LD11 to LD15 and a combined optical system 250. The semiconductor lasers LD11 to LD15 are arranged along an arc.

  The multiplexing optical system 250 is provided with condensing lenses H11 to H15 for condensing the beams B11 to B15 emitted from the semiconductor lasers LD11 to LD15, respectively. Each of the semiconductor lasers LD <b> 11 to LD <b> 15 is disposed so that its optical axis faces one point on one end surface of the core 251 a of the multimode optical fiber 251. The condensing lenses H11 to H15 are arranged to converge the beams B11 to B15 on this one point.

  The beams B11 to B15 incident on the core 251a are combined into one beam B10 and emitted from the multimode optical fiber 251. The maximum incident angle θ of the beams B11 to B15 is a value within the maximum light receiving angle corresponding to the NA (numerical aperture) of the multimode optical fiber 251.

Further, an optical power combining optical system disclosed in Japanese Patent Application Laid-Open No. 2005-114977 (Patent Document 2) is a combination laser light source disclosed in Japanese Patent Application Laid-Open No. 2002-202442 (Patent Document 1). The anamorphic optical element (for example, prism array etc.) for narrowing the width of the parallel light is combined. The optical power combining optical system disclosed in Japanese Patent Laid-Open No. 2005-149777 (Patent Document 2) can reduce the optical path length, and thus can be miniaturized.
JP 2002-202442 A JP 2005-149777 A

  The conventional optical system as shown in FIGS. 27 and 28 needs to include a plurality of collimating lenses corresponding to each of a plurality of light sources and one large-diameter condenser lens. Since these optical systems have a large number of parts, the configuration becomes complicated. In these optical systems, since a plurality of light sources are arranged one-dimensionally, the diameter of the condenser lens must be increased as the number of light sources increases. Therefore, the scale of these optical systems inevitably increases.

  Further, the optical fiber has a NA (numerical aperture) limit. In order to efficiently couple light to a light receiver having a NA limitation, it is necessary to make the NA of the condenser lens smaller than the NA of the light receiver. However, when a condensing lens having an NA smaller than the NA of the light receiver is used in the optical system, the diameter of the condensing lens increases and the focal length increases. This increases the size of the optical system.

  Furthermore, when the focal length of the condensing lens is increased, the diameter of the condensed light beam is also increased. For this reason, when light is coupled to a light receiver having a small light receiving area such as an optical fiber, there is a problem that a part of the light flux protrudes from the light receiving area.

  An object of the present invention is to provide a laser module that is small and capable of outputting high-power light.

  In summary, the present invention is a laser module, which is provided corresponding to a plurality of surface-emitting lasers and two or more surface-emitting lasers arranged two-dimensionally at a predetermined interval on the same plane, And a plurality of optical fibers in which the central axes of the one end portions are arranged at predetermined intervals and the one end portions are bundled. The plurality of optical fibers are arranged so that the central axis of each one end thereof overlaps the optical axis of the laser beam emitted from the corresponding surface emitting laser among the plurality of surface emitting lasers.

  By arranging a plurality of surface emitting lasers two-dimensionally on the same plane, the scale of the optical system can be prevented from becoming extremely large. Since the interval between the plurality of surface emitting lasers and the interval between the plurality of optical fibers are the same, the alignment between the surface emitting laser and the optical fiber corresponding to the surface emitting laser can be easily performed. Furthermore, since one end portions (end portions on the side on which the laser beam is incident) of the plurality of optical fibers are bundled, it is possible to prevent the interval between the one end portions of the optical fibers from changing. As a result, it is possible to realize a small laser module that can output a high-power laser beam.

  Preferably, the plurality of surface emitting lasers are arranged point-symmetrically on a plane. As a result, the end faces on the side on which the laser beams are incident are also arranged point-symmetrically in the plurality of optical fibers. Therefore, even when the number of surface emitting lasers is increased, it is possible to easily align the plurality of surface emitting lasers and the plurality of optical fibers.

  More preferably, the plurality of surface emitting lasers are a plurality of first surface emitting lasers and a plurality of surface emitting lasers arranged in a hexagonal shape at a predetermined distance from the optical axis of the laser beam emitted from the first surface emitting laser. And a second surface emitting laser. Thus, the plurality of optical fibers can be arranged in a so-called honeycomb shape, and the plurality of optical fibers can be densely packed. As a result, the power density of the light output from the laser module can be increased.

  Preferably, the laser module further includes a plurality of fixing members provided corresponding to the plurality of optical fibers, each having a through hole formed therein. One end of each of the plurality of optical fibers is inserted into the through hole. The plurality of fixing members are bundled. Thereby, it can fix so that one end part of an optical fiber may not move.

  Preferably, the laser module further includes a fixing member formed with a plurality of through holes corresponding to the plurality of optical fibers. One end of each of the plurality of optical fibers is inserted into a corresponding through hole among the plurality of through holes. Thereby, it can fix so that one end part of an optical fiber may not move.

  Preferably, the laser module further includes a sleeve into which one end of each of the plurality of optical fibers is inserted. In this case, the mounting density of the optical fiber can be increased. That is, surface emitting lasers can be arranged with high density. For this reason, the power of the laser beam output from the laser module can be increased.

  Preferably, the other ends of the plurality of optical fibers are bundled so that the interval between the central axes of the other ends is narrower than a predetermined interval. Thereby, since the light output from a laser module can be condensed in a narrow range, the light of high power density suitable for fine processing etc. can be obtained, for example.

  Preferably, the laser module further includes a plurality of lenses that are provided corresponding to the plurality of surface emitting lasers and collect laser beams emitted from the corresponding surface emitting lasers. As a result of focusing the laser beam by the lens, the laser beam can be coupled to the incident end face of the optical fiber with high efficiency. Therefore, the power of the laser beam output from the laser module can be further increased.

  According to the laser module of the present invention, high-power light can be output while being small.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

[Embodiment 1]
FIG. 1 is a diagram illustrating an overall configuration of the laser module according to the first embodiment.

  Referring to FIG. 1, laser module 1 according to the first embodiment is an apparatus that can be used, for example, for processing products or soldering components on a circuit board.

  The laser module 1 includes a plurality of vertical cavity surface emitting lasers (VCSELs) 11, a plurality of optical fibers 12, a package 15, a plurality of ferrules 20, and sleeves 21 and 22.

  The plurality of surface emitting lasers 11 are two-dimensionally arranged on the surface of the package 15 at a predetermined interval. The plurality of surface emitting lasers 11 emit a plurality of laser beams, respectively. The plurality of optical fibers 12 are provided corresponding to the plurality of surface emitting lasers 11, respectively, and receive laser beams emitted from the corresponding surface emitting lasers 11 at each one end. The interval between the one end portions of the optical fiber 12 is equal to the interval between the surface emitting lasers 11 (that is, a predetermined interval).

  One end of the optical fiber 12 is inserted into the through hole of the ferrule 20. A ferrule is a component used to hold an optical fiber within an optical connector. The ferrule has a so-called cylindrical shape, and a through hole is formed at the position of the central axis. By passing one end of the optical fiber through the through hole, the position of the one end of the optical fiber is fixed. In the case of an optical connector, two ferrules into which optical fibers are inserted are prepared, and the two ferrules are abutted in a pipe-shaped sleeve. Thereby, two optical fibers are connected in the optical connector.

  FIG. 2 is a diagram illustrating a configuration of a portion including the surface emitting laser 11, the optical fiber 12, and the ferrule 20 in the laser module 1 illustrated in FIG. 1.

  Referring to FIGS. 2 and 1, the surface of package 15 is formed in a flat shape. The plurality of surface emitting lasers 11 are two-dimensionally arranged on the surface of the package 15.

  For example, in the optical system shown in FIG. 28, a plurality of semiconductor lasers are arranged one-dimensionally. Therefore, the scale of the optical system tends to become extremely large as the number of semiconductor lasers increases. However, according to the present embodiment, since the plurality of surface emitting lasers 11 are two-dimensionally arranged on the same plane, even if the number of surface emitting lasers 11 is increased, the scale of the optical system is prevented from becoming extremely large. Can do.

  The plurality of optical fibers 12 are respectively provided corresponding to the plurality of surface emitting lasers 11. Each of the plurality of surface emitting lasers 11 emits a laser beam LB. Each of the plurality of optical fibers 12 receives a corresponding laser beam LB. Unlike the conventional optical system shown in FIGS. 27, 28, etc., in this embodiment, the laser beam is directly coupled to the optical fiber 12 without using an optical system such as a lens.

  The plurality of ferrules 20 are bonded to each other with an adhesive and further packed into the sleeve 22. Thereby, the plurality of ferrules 20 are fixed so as not to move. For this reason, it is possible to prevent the position of one end of the optical fiber from shifting in the sleeve 22.

  The structural unit A includes a surface emitting laser 11 and an optical fiber 12. The structural unit A is shown in FIG. 2 in order to explain the arrangement of the surface emitting laser 11 and the optical fiber 12 corresponding to the surface emitting laser in detail later.

  Returning to FIG. 1, end portions (the other end portions) on the side of emitting the laser beam in the plurality of optical fibers 12 are bundled by the sleeve 21.

FIG. 3 is a view showing the inside of the sleeve 21 of FIG.
With reference to FIG. 3 and FIG. 1, inside the sleeve 21, the plurality of optical fibers 12 are arranged in a honeycomb shape so as to have as little gap as possible. As can be seen by comparing FIG. 3 and FIG. 1, the distance between the other ends of the optical fiber is narrower than the distance between the one ends of the optical fiber. Thereby, a plurality of laser beams output from the laser module 1 can be condensed within a very narrow range (for example, within a circle having a diameter of about several hundred μm).

  The length of the middle part of the optical fiber (the remaining part excluding the one end and the other end) is, for example, several tens of centimeters. For example, a plurality of optical fibers may be combined by bundling this portion with a spiral tube or the like.

FIG. 4 is an enlarged view of the structural unit A shown in FIG.
Referring to FIG. 4, the surface emitting laser 11 has a light emitting surface 11E that emits a laser beam LB. The optical fiber 12 includes a core 121 and a clad 122 provided around the core 121.

  The axis J indicates the central axis of the optical fiber 12 (in other words, the central axis of the core 121). The arrangement of the optical fiber 12 with respect to the surface emitting laser 11 is determined so that the axis J overlaps the optical axis of the laser beam LB. By arranging the optical fiber 12 in this way, the coupling efficiency of the laser beam LB at one end of the optical fiber 12 can be increased.

  The optical fiber 12 is an “optical fiber with a large core diameter”. More specifically, for example, the ratio of the diameter D1 of the core 121 to the diameter D2 of the cladding 122 (in other words, the diameter of the optical fiber 12) is set to be about 90% or more.

  As a fiber having a large core diameter, a so-called “multimode optical fiber” (an optical fiber capable of propagating a plurality of modes of light) is known. In the case of a multimode optical fiber, for example, the diameter of the cladding 122 is 125 μm, and the diameter of the core is about 50 μm. In this example, the ratio of the core diameter to the cladding diameter is about 40% (= 50/125). From this, it can be seen that in the optical fiber used in the present embodiment, the ratio of the diameter of the core to the diameter of the cladding is relatively large.

  The larger the diameter of the core 121, the smaller the ratio of the diameter of the laser beam LB to the diameter of the core at the end face of the optical fiber. That is, the laser beam easily enters the core 121. Therefore, the laser beam can be efficiently combined at the incident end face of the optical fiber.

  Further, in the present embodiment, a surface emitting laser is used as a light source for generating a laser beam. As a result, the laser beam can be efficiently coupled to the incident end face of the optical fiber.

A surface emitting laser is a semiconductor laser whose light resonating direction is perpendicular to the substrate surface. As is well known, there is a type of semiconductor laser that emits laser light from a cleaved surface of a crystal (so-called edge emitting semiconductor laser). A surface emitting laser generally has a smaller laser beam divergence angle than an edge emitting semiconductor laser. The “divergence angle” refers to the direction in which the power density of the laser beam is maximized (the direction along the axis J in FIG. 4), and the laser beam power density is 1 / e ² (e: natural logarithm) of the maximum value. It means the angle made with the direction.

  In FIG. 4, the spread angle of the laser beam LB is denoted by θ. Since the directivity of the laser beam is stronger as the divergence angle θ is smaller, the diameter of the laser beam at the incident end face of the optical fiber 12 becomes smaller. Therefore, the laser beam can be efficiently combined at the incident end face of the optical fiber. That is, by using a surface emitting laser as a light source, a laser beam can be efficiently coupled to the incident end face of the optical fiber.

FIG. 5 is a cross-sectional view taken along line VV in FIG.
Referring to FIG. 5, the plurality of ferrules 20 are arranged in a so-called honeycomb shape so that a gap is not generated as much as possible. Since an optical fiber is inserted at the center of each ferrule 20, the optical fiber 12 is arranged to draw a regular hexagon around the point P1. More specifically, the central axis of the optical fiber 12A passes through the point P1. Six optical fibers 12B are arranged around the optical fiber 12A. The position of the central axis of the optical fiber 12B corresponds to the position of each vertex of the regular hexagon centered on the point P1.

  Accordingly, the distances from the point P1 to each of the six optical fibers 12B are all equal. In order to prevent the figure from becoming complicated, in FIG. 5, the distance from one of the six optical fibers 12B to the point P1 is denoted by d.

6 is a cross-sectional view taken along line VI-VI in FIG.
Referring to FIG. 6, the plurality of surface emitting lasers 11 are arranged symmetrically with respect to point P2. More specifically, the plurality of surface emitting lasers 11 include a surface emitting laser 11A and six surface emitting lasers 11B. The point P2 is located on the surface emitting laser 11A. The point P2 is a point on the optical axis of the laser beam emitted from the surface emitting laser 11A. The six surface emitting lasers 11B are arranged at the positions of the vertices of a regular hexagon centered on the point P1. Therefore, the distances from the point P1 to each of the six surface emitting lasers 11B are all equal. This distance is equal to the distance d shown in FIG.

  Thus, in the present embodiment, a plurality of surface emitting lasers are arranged point-symmetrically (more preferably in a regular hexagonal shape). An optical axis of a laser beam emitted from a surface emitting laser coincides with a central axis of an optical fiber corresponding to the surface emitting laser.

  Therefore, as shown in FIG. 5, the end faces of the plurality of optical fibers are also arranged point-symmetrically. In addition, one end portions of the plurality of optical fibers are fixed so as not to move by the ferrule. Thereby, alignment with a some surface emitting laser and a some optical fiber can be performed easily.

  The method for aligning the plurality of surface emitting lasers and the plurality of optical fibers is, for example, as follows. First, the position of the optical fiber 12A is adjusted so that the central axis of the optical fiber 12A passes through the optical axis of the laser beam of the surface emitting laser 11A. Next, the optical axis of the optical fiber 12A is centered so that the optical axis of the laser beam emitted from any one of the six surface emitting lasers 11B coincides with the central axis of any one of the six optical fibers 12B. The plurality of optical fibers 12 are rotated as a whole.

  By this adjustment, the remaining optical fibers 12B and the optical fibers arranged around the optical fibers 12B can be arranged at the same time.

  When positioning the surface emitting laser and the optical fiber by the above method, there is a concern about the accuracy of the size of the ferrule itself. This is because, if the dimensional error of the ferrule itself is large, the end face of the optical fiber 12 cannot be arranged point-symmetrically as shown in FIG.

  In such a case, the optical fiber 12 located farther away from the point P1 has the optical axis of the laser beam of the surface emitting laser corresponding to the optical fiber 12 greatly deviated from the central axis of the optical fiber 12. Is expected. As a result, the power of the laser beam output from the laser module may decrease.

  However, in a ferrule that has been commercialized, the outer diameter error is, for example, 1 μm or less. The concentricity (center deviation) between the outer diameter and the through hole is, for example, 1 μm or less. As described above, since the dimensional accuracy of the ferrule is high, in the present embodiment, a plurality of ferrules can be arranged symmetrically (in a honeycomb shape) with respect to the point P1.

  Further, even when the position of the surface emitting laser 11 on the package surface deviates from the designed position, the coupling efficiency on the end face of the optical fiber 12 may be reduced. Such a problem can be dealt with by mounting a surface emitting laser on a package using a die bonder. The mounting accuracy of the die bonder is, for example, ± 15 μm. As described below, if the surface emitting laser 11 is mounted on the surface of the package with an accuracy within ± 15 μm with respect to the design position, a practically sufficient level of coupling efficiency can be obtained.

(Characteristics of laser module)
In order to evaluate the characteristics of the laser module of the present embodiment, the coupling efficiency in the structural unit A shown in FIG. 4 is determined by a ray tracing method (a method in which the laser beam is divided into a number of rays and the locus of each ray is traced). It was obtained by running a simulation.

FIG. 7 is a diagram for explaining a simulation model by the ray tracing method.
Referring to FIG. 7, in the simulation model, the diameter of the core 121 of the optical fiber 12 was set to 112 μm. The emission diameter of the laser beam LB on the light emitting surface 11E of the surface emitting laser 11 was set to 20 μm. The spread angle θ of the laser beam LB was set to 6 degrees. The distance between the surface emitting laser 11 and the optical fiber 12 was set to 0.5 mm.

  In FIG. 7, the X-axis direction is a direction along the diameter of the optical fiber 12. When executing the simulation, the X-axis direction was set to a certain direction. The Y-axis direction was set as the direction perpendicular to the X-axis direction.

  FIG. 8 is a diagram showing a result of obtaining a relationship between the distance between the laser beam and the optical fiber and the coupling efficiency by simulation using the model shown in FIG.

  Referring to FIG. 8, “tolerance” shown on the X axis of the graph indicates a distance between the center axis of the optical fiber and the optical axis of the laser beam (a distance in the X axis direction shown in FIG. 7). In the simulation, the surface emitting laser was moved with the position of the optical fiber fixed.

  A plurality of curves on the graph move the optical axis of the laser beam from −50 to +50 μm in the X-axis direction shown in FIG. 7 from the state where the central axis of the optical fiber and the optical axis of the laser beam overlap, and FIG. 7 shows a change in coupling efficiency when the optical axis of the laser beam is moved in a 5 μm step from 0 to +40 μm in the Y-axis direction shown in FIG.

  From the graph of FIG. 8, it can be seen that if the alignment accuracy of the optical axis of the laser beam with respect to the central axis of the optical fiber is set within ± 15 μm in both the X-axis direction and the Y-axis direction, the coupling efficiency becomes 80% or more. A coupling efficiency of 80% or more is a practically sufficient level.

  Using this result, the optical output of the laser module 1 shown in FIG. 1 is obtained as follows. For example, the light output of one surface emitting laser is 35 mW, and the number of surface emitting lasers is 19. In this case, the optical output of the laser module 1 is 0.035 × 19 × 0.8 = 0.532 (W).

  FIG. 9 is a diagram illustrating a simulation result of a change in coupling efficiency with respect to the spread angle of the laser beam.

  Referring to FIG. 9, the curve of the graph is obtained when the divergence angle of the laser beam is changed in the range of 0 degrees to 15 degrees in a state where the optical axis of the laser beam and the central axis of the optical fiber coincide with each other. Changes in coupling efficiency are shown. Each of a plurality of points on the curve shows the result of obtaining the coupling efficiency with respect to the divergence angle of the laser beam by the ray tracing method.

  The coupling efficiency increases as the spread angle of the laser beam decreases. For example, if the spread angle of the laser beam is 7 degrees or less, the coupling efficiency is 80% or more, and if the spread angle is 4 degrees or less, the coupling efficiency is almost 100%.

(Method of fixing one end of optical fiber)
FIG. 10 is a diagram illustrating a method for fixing a plurality of ferrules in a sleeve.

  Referring to FIG. 10, nineteen ferrules 20 are fixed in the sleeve 22 in accordance with the following procedures (1) to (3).

  (1) A predetermined number (three, four, five) of ferrules 20 are brought into close contact and fixed with an adhesive 24, and a plurality of ferrule bundles are created.

  (2) A bundle of three, four, five, four, and three ferrules are in close contact and stacked in order from the bottom, and these bundles are fixed with an adhesive. By this step, a plurality of ferrules are arranged according to the arrangement of the plurality of surface emitting lasers.

(3) The ferrule 20 is fixed by inserting a bundle of ferrules 20 into the sleeve 22.
FIG. 11 is a diagram illustrating a method of fixing an optical fiber in a ferrule.

  Referring to FIG. 11, optical fiber 12 is inserted into ferrule 20, and optical fiber 12 is fixed with adhesive 24. As shown in FIG. 11, the optical fiber 12 may be inserted into the ferrule 20 with the optical fiber 12 passed through the tube 26 so that the side surface of the optical fiber 12 is not damaged.

FIG. 12 is a diagram for explaining the processing of the plurality of ferrules 20.
Referring to FIG. 12, a portion C including a plurality of ferrules and fiber end faces is polished. If an adhesive is applied to the ferrule to fix the tip of the optical fiber, the tip (end surface) of the optical fiber may be blocked by the adhesive. For this reason, the tip of the optical fiber is polished.

(Other methods for fixing one end of an optical fiber)
In the configuration of the laser module 1 described above, one end of the optical fiber 12 is inserted into a through hole formed in the ferrule. However, the member for fixing one end of the optical fiber 12 is not limited to a ferrule.

FIG. 13 is a diagram illustrating another example of a method of fixing one end of a plurality of optical fibers.
Referring to FIG. 13, one end of each of the plurality of optical fibers is inserted into a plurality of through holes provided in capillary plate 20A. Similar to the ferrule, the capillary plate is a member for holding the optical fiber in the optical connector. The material of the capillary plate 20A is quartz, resin or the like, but the capillary plate made of resin is widely used in communication modules. By using a resin capillary plate, the cost of the laser module can be reduced.

  Each one end of the plurality of optical fibers 12 is fixed with an adhesive, and the end surface of the one end is polished.

FIG. 14 is a view showing the inside of the capillary plate 20A shown in FIG.
15 is a cross-sectional view taken along line XV-XV in FIG.

  Referring to FIGS. 15 and 14, 16 optical fibers 12 are arranged in 4 rows and 4 columns inside capillary plate 20 </ b> A. The interval between the plurality of optical fibers 12 is, for example, 250 μm. As shown in FIG. 15, in the capillary plate 20A, the 16 optical fibers 12 are arranged symmetrically around the point P1.

16 is a cross-sectional view taken along line XVI-XVI in FIG.
Referring to FIGS. 16 and 14, surface emitting laser array 11C includes a plurality of surface emitting lasers 11 arranged two-dimensionally. As in FIG. 1, a plurality of chip-shaped surface emitting lasers 11 may be mounted on the surface of the package.

  The plurality of surface emitting lasers 11 are arranged symmetrically around the point P2. Therefore, as shown in FIG. 15, the 16 optical fibers 12 are also arranged symmetrically about the point P1.

FIG. 17 is a diagram showing still another example of a method for bundling one end portions of a plurality of optical fibers.
Referring to FIG. 17, the plurality of optical fibers 12 are directly inserted into the sleeve 22.

18 is a view showing the inside of the sleeve 22 shown in FIG.
FIG. 19 is a cross-sectional view taken along line XIX-XIX in FIG.

  Referring to FIGS. 19 and 18, a plurality of optical fibers 12 are arranged symmetrically around point P <b> 1 inside sleeve 22. In particular, as shown in FIG. 19, the plurality of optical fibers are arranged on a regular hexagonal outline centered on the point P1. The central axis of the optical fiber 12A passes through the point P1.

  As can be seen by comparing FIG. 19 and FIG. 5, in the configuration example shown in FIG. 19, the ferrule is not inserted into the sleeve 22, so the inner diameter D12 of the sleeve 22 is larger than the inner diameter D11 of the sleeve 22 shown in FIG. Significantly smaller.

20 is a cross-sectional view taken along line XX-XX in FIG.
20 and 18, surface emitting laser array 11C includes a plurality of surface emitting lasers 11 arranged two-dimensionally. As in FIG. 1, a plurality of chip-shaped surface emitting lasers 11 may be mounted on the surface of the package. The plurality of surface emitting lasers 11 are arranged symmetrically around the point P2.

  A reduction in the interval between the plurality of optical fibers means a reduction in the interval between the plurality of surface emitting lasers 11. That is, the surface emitting laser 11 is included in the surface emitting laser array 11C at a high density. Therefore, in the case of the configuration examples shown in FIGS. 17 to 20, the power of the laser beam output from the laser module can be further increased.

(Example of the number of optical fibers)
In order to increase the power of the laser beam output from the laser module 1, it is necessary to increase the number of surface emitting lasers 11 and the number of optical fibers 12. On the other hand, the plurality of optical fibers (if using a ferrule, the ferrule) must be arranged with as little gap as possible so that the positions of the plurality of optical fibers do not shift. For this reason, a plurality of optical fibers (or a plurality of ferrules) are arranged in a honeycomb shape. For this reason, the number and arrangement of the plurality of optical fibers are determined as follows.

FIG. 21 is a diagram illustrating the number and arrangement of the plurality of optical fibers 12 in a table format.
FIG. 21 shows an example of the number of optical fibers 12 (19, 37, 61, 91, 127) and the arrangement of a plurality of optical fibers corresponding to the number.

FIG. 22 is a diagram illustrating a state in which the number of optical fibers illustrated in FIG. 21 are bundled.
FIG. 22 shows a state where 19 optical fibers are bundled, a state where 37 optical fibers are bundled, and a state where 61 optical fibers are bundled. The broken line shown in FIG. 22 is for showing the optical fiber arranged at the “center” shown in FIG. Further, “upper” and “lower” directions indicated by arrows in FIG. 22 are shown for explaining “upper first stage”, “lower first stage” and the like in FIG. By arranging a plurality of optical fibers as shown in FIGS. 21 and 22, it is possible to arrange a plurality of optical fibers in a so-called honeycomb shape while preventing the positions of the plurality of optical fibers from shifting.

(Method of deforming the laser beam output from the laser module)
An optical system for deforming a plurality of laser beams output from the laser module 1 shown in FIG. 1 will be described. By deforming the laser beam as described below, the laser module of the present embodiment can be used for fine processing, for example.

FIG. 23 is a diagram illustrating an optical system for converting a laser beam into collimated light.
Referring to FIG. 23, a plurality of optical fibers (not shown) are bundled by sleeve 21. In the following description, the bundled optical fibers are referred to as “bundle fibers”. The laser beam output from the bundle fiber is converted into collimated light (substantially parallel light) by the collimating lens 31.

FIG. 24 is a diagram illustrating the configuration of an optical system for reducing the diameter of the laser beam.
Referring to FIG. 24, a plurality of optical fibers (not shown) are bundled by sleeve 21 as in FIG. The outer diameter of the bundle fiber is 1320 μm. The numerical aperture NA1 of each of the plurality of optical fibers is 0.2.

  Laser light emitted from the bundle fiber enters a light guide 34 having a core diameter of 600 μm via a collimating lens 32 and an imaging lens 33. That is, in the optical system shown in FIG. 24, the size of the laser beam emitted from the bundle fiber having an outer diameter of 1320 μm is reduced to the size of the core diameter of the light guide 34 (600 μm). This increases the power per unit area of the laser beam and makes it possible to obtain a sharp (small spread angle) laser beam.

  The reduction ratio m ′ at this time is m ′ = 600/1320 = 0.455. Further, when the numerical aperture required for the light guide 34 is NA2, there is a relationship of m ′ ≧ NA1 / NA2.

  Between the ratio (reduction ratio) of the core diameter of the light guide to the outer diameter of the bundle fiber, the numerical aperture (NA1) of the optical fiber constituting the bundle fiber, and the numerical aperture (NA2) of the optical guide, NA2 ≧ ( (NA1 / reduction rate) × η relationship holds. Here, η is a coefficient determined by the cladding thickness of the optical fiber. The laser beam that is effectively emitted from the bundle fiber varies depending on at least the thickness (or cross-sectional shape, etc.) of the outermost cladding of the bundle fiber. Assuming that the actual reduction ratio is m, m = m ′ / η ≧ (NA1 / NA2), and NA2 ≧ (NA1 / m ′) η. The coefficient η is usually smaller than 1 and larger than 0.7. In the above example, when η is 0.9, NA2 is 0.41.

  The collimating lens 32 has a focal length f1 of 100 mm, and the imaging lens 33 has a focal length f2 of 45 mm. By using these lenses, the laser beam emitted from the bundle fiber can be incident on the light guide 34 with NA2 = 0.41.

  A hand grip 35 with a built-in imaging lens is attached to the tip of the light guide 34. By setting the focal length of the imaging lens to 8 mm, a high-power laser beam having a spot size of 0.4 mm can be obtained.

  As described above, according to the first embodiment, the laser modules are respectively provided corresponding to the plurality of surface emitting lasers and the plurality of surface emitting lasers arranged two-dimensionally at a predetermined interval on the same plane. And a plurality of optical fibers in which the central axes of the one end portions are arranged at predetermined intervals and the one end portions are bundled. The plurality of optical fibers are arranged so that the central axis of each one end thereof overlaps the optical axis of the laser beam emitted from the corresponding surface emitting laser among the plurality of surface emitting lasers.

  By arranging a plurality of surface emitting lasers two-dimensionally on the same plane, the scale of the optical system can be prevented from becoming extremely large. Since the interval between the plurality of surface emitting lasers and the interval between the plurality of optical fibers are the same, the alignment between the surface emitting laser and the optical fiber corresponding to the surface emitting laser can be easily performed. Furthermore, since one end portions (end portions on the side on which the laser beam is incident) of the plurality of optical fibers are bundled, it is possible to prevent the interval between the one end portions of the optical fibers from changing. As a result, it is possible to realize a small laser module that can output a high-power laser beam.

  Further, according to the first embodiment, the plurality of surface emitting lasers are arranged point-symmetrically on the same plane. As a result, the end faces on the side on which the laser beams are incident are also arranged point-symmetrically in the plurality of optical fibers. Therefore, even when the number of surface emitting lasers is increased, it is possible to easily align the plurality of surface emitting lasers and the plurality of optical fibers.

  Further, according to the first embodiment, the plurality of surface emitting lasers are hexagonally shaped at a predetermined distance from the optical axis of the first surface emitting laser and the laser beam emitted from the first surface emitting laser. And a plurality of second surface emitting lasers. Thus, the plurality of optical fibers can be arranged in a so-called honeycomb shape, and the plurality of optical fibers can be densely packed. As a result, the power density of the light output from the laser module can be increased.

  According to the first embodiment, the laser module further includes a plurality of fixing members (ferrules) provided corresponding to the plurality of optical fibers, each having a through hole. One end of each of the plurality of optical fibers is inserted into the through hole. The plurality of fixing members are bundled. Thereby, it can fix so that one end part of an optical fiber may not move.

  According to the first embodiment, the laser module includes the fixing member (capillary plate) in which a plurality of through holes are formed corresponding to the plurality of optical fibers. One end of each of the plurality of optical fibers is inserted into a corresponding through hole among the plurality of through holes. Thereby, it can fix so that one end part of an optical fiber may not move.

  According to the first embodiment, the laser module includes the sleeve into which one end of each of the plurality of optical fibers is inserted. In this case, the mounting density of the optical fiber can be increased as compared with the case where a ferrule is used. That is, surface emitting lasers can be arranged with high density. For this reason, the power of the laser beam output from the laser module can be increased.

  Further, according to the first embodiment, the other ends of the plurality of optical fibers are bundled so that the interval between the central axes of the other ends is narrower than a predetermined interval. Thereby, since the light output from a laser module can be condensed in a narrow range, the light of high power density suitable for fine processing etc. can be obtained, for example.

[Embodiment 2]
FIG. 25 is a diagram illustrating a configuration of a laser module according to the second embodiment.

  Referring to FIGS. 25 and 1, laser module 1 </ b> A is different from laser module 1 in that it further includes a plurality of lenses 41 provided corresponding to a plurality of surface emitting lasers 11. Since the structure of the other part of laser module 1A is the same as that of the corresponding part of laser module 1, the following description will not be repeated.

FIG. 26 is a schematic diagram for explaining the lens 41 shown in FIG.
Referring to FIG. 26, the lens 41 is mounted on the light emitting surface of the surface emitting laser 11. The lens 41 serves to reduce the spread angle of the laser beam from the surface emitting laser 11. As shown in FIG. 9, the smaller the divergence angle, the higher the coupling efficiency.

  The lens 41 is a minute lens (so-called “inkjet microlens”) formed using, for example, an inkjet technique. The inkjet microlens is produced as follows, for example. First, the surface of the surface emitting laser 11 is subjected to water repellent processing. Next, a lens material is discharged onto the surface of the surface emitting laser 11 to form a spherical lens. Subsequently, the lens is cured by ultraviolet irradiation or the like.

  The smaller the divergence angle of the laser beam and the smaller the laser beam diameter, the easier it is for the laser beam to enter the core of the optical fiber. As a result, the laser beam can be coupled to the incident end face of the optical fiber with high efficiency. Therefore, the power of the laser beam output from the laser module can be further increased. In addition, the tolerance (tolerance) of positional deviation between the surface emitting laser 11 and the optical fiber can be increased.

  In the second embodiment, since the lens formed on the surface of the surface emitting laser 11 is very small, it is possible to prevent the size of the laser module from increasing.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is a diagram illustrating an overall configuration of a laser module according to Embodiment 1. FIG. It is a figure explaining the structure of the part containing the surface emitting laser 11, the optical fiber 12, and the ferrule 20 among the laser modules 1 shown in FIG. It is a figure which shows the inside of the sleeve 21 of FIG. It is a figure which expands and shows the structural unit A shown in FIG. It is sectional drawing along the VV line of FIG. It is sectional drawing along the VI-VI line of FIG. It is a figure explaining the model of the simulation by a ray tracing method. It is a figure which shows the result of having calculated | required the relationship between the distance between a laser beam and an optical fiber, and the coupling efficiency using the model shown in FIG. It is a figure which shows the simulation result of the change of coupling efficiency with respect to the divergence angle of a laser beam. It is a figure explaining the method for fixing a some ferrule in a sleeve. It is a figure explaining the method to fix an optical fiber in a ferrule. It is a figure explaining the processing of a plurality of ferrules 20. It is a figure which shows the other example of a method of fixing the one end part of a some optical fiber. It is a figure which shows the inside of the capillary plate 20A shown in FIG. It is sectional drawing along the XV-XV line | wire of FIG. It is sectional drawing along the XVI-XVI line of FIG. It is a figure which shows another example of a method of bundling the one end part of a some optical fiber. It is a figure which shows the inside of the sleeve 22 shown in FIG. It is sectional drawing along the XIX-XIX line | wire of FIG. It is sectional drawing along the XX-XX line of FIG. It is a figure explaining the number and arrangement of a plurality of optical fibers 12 in a tabular form. It is a figure which shows the state which bundled the number of optical fibers shown in FIG. It is a figure explaining the optical system for converting a laser beam into collimated light. It is a figure explaining the structure of the optical system for making the diameter of a laser beam small. FIG. 4 is a diagram illustrating a configuration of a laser module according to a second embodiment. It is a schematic diagram explaining the lens 41 shown in FIG. It is a figure explaining the structure of the combining laser light source disclosed by Unexamined-Japanese-Patent No. 2002-202442 (patent document 1). It is a figure explaining another structure of the combining laser light source disclosed by Unexamined-Japanese-Patent No. 2002-202442 (patent document 1).

Explanation of symbols

  1, 1A laser module, 11, 11A, 11B surface emitting laser, 11C surface emitting laser array, 11E emitting surface, 12, 12A, 12B optical fiber, 15 package, 20 ferrule, 20A capillary plate, 21, 22 sleeve, 24 bonding Agent, 26 tube, 31, 32, 111-117 collimating lens, 33 imaging lens, 34 light guide, 35 hand grip, 41 lens, 110 heat block, 120 condenser lens, 121, 130a, 251a core, 122 cladding, 130,251 Multimode optical fiber, 250 multiplexing optical system, A structural unit, B, B1-B15 beam, H11-H15 condenser lens, J-axis, LD1-LD15 semiconductor laser, P1, P2 points.

Claims (8)

A plurality of surface emitting lasers arranged two-dimensionally at predetermined intervals on the same plane;
A plurality of optical fibers provided corresponding to the plurality of surface emitting lasers, each having a central axis of one end thereof arranged at the predetermined interval, and a plurality of optical fibers bundled with the one end;
The plurality of optical fibers are arranged such that a central axis of each of the one end portions thereof overlaps with an optical axis of a laser beam emitted from a corresponding surface emitting laser among the plurality of surface emitting lasers. .   The laser module according to claim 1, wherein the plurality of surface emitting lasers are arranged point-symmetrically on the plane. The plurality of surface emitting lasers are:
A first surface emitting laser;
3. The laser according to claim 2, further comprising: a plurality of second surface emitting lasers arranged in a hexagonal shape at a position separated from the optical axis of a laser beam emitted from the first surface emitting laser by the predetermined interval. module. The laser module is
A plurality of fixing members each provided corresponding to the plurality of optical fibers, each having a through hole;
The one end of each of the plurality of optical fibers is inserted into the through hole,
The laser module according to claim 1, wherein the plurality of fixing members are bundled. The laser module is
Further comprising a fixing member formed with a plurality of through holes corresponding to the plurality of optical fibers,
The laser module according to claim 1, wherein the one end portion of each of the plurality of optical fibers is inserted into a corresponding through hole of the plurality of through holes. The laser module is
The laser module according to claim 1, further comprising a sleeve into which the one end of each of the plurality of optical fibers is inserted.   2. The laser module according to claim 1, wherein the other end portions of the plurality of optical fibers are bundled so that an interval between central axes of the other end portions is narrower than the predetermined interval.   2. The laser module according to claim 1, further comprising a plurality of lenses that are respectively provided corresponding to the plurality of surface emitting lasers and condense a laser beam emitted from the corresponding surface emitting laser.

Images