JP2005026610A - Semiconductor laser array - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor laser array which can improve a beam density by raising an array density of a light emitting region. <P>SOLUTION: The semiconductor laser array 1 includes a p-type clad layer 11, an n-type clad layer 15, and an active layer 13. The active layer 13 has a refractive index waveguide 3 which has a reflecting end face 35 disposed on a light reflecting surface 6, an emitting end face 37 disposed on a light emitting surface 4 and formed discontinuously in a region opposed to the reflecting end face 35, and a pair of side faces 39a, 39b extended from the reflecting end face 35 to the emitting end face 37 to specify a region in the longitudinal direction of the refractive index waveguide 3. The side faces 39a, 39b are formed to totally reflect the beam incident from a direction perpendicular to the light emitting surface 4 from the light emitting surface 4 toward the reflecting end face 35. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a semiconductor laser array.

A semiconductor laser device including a semiconductor laser array in which light emitting regions emitting laser light are arranged in parallel along the longitudinal direction is used in a wide range of fields such as solid-state laser excitation, printing, material processing, and medicine. However, the laser light emitted from each light emitting region of the semiconductor laser array has a large beam diffusion angle. For example, the beam diffusion angle of the emitted laser light in the longitudinal direction (hereinafter referred to as “horizontal direction”) is about 8 °, and the direction perpendicular to both the emission direction and the longitudinal direction of the laser light (hereinafter referred to as “horizontal direction”). )) Is about 30 to 35 °. Since it has such a diffusion angle, it is necessary to shape the laser beam in order to obtain a high light density. To facilitate the shaping, the laser beam emitted from the semiconductor laser array is horizontal using an optical system. It is parallel to the direction and the vertical direction (see, for example, Non-Patent Document 1).
Hirofumi Tsuji, Hirofumi Miyajima et al., Journal of Laser Processing 9, 2002, 18

  Parallelization of the laser array light in the vertical direction can be performed relatively easily by using a cylindrical collimating lens or the like. However, since a plurality of light emitting regions are arranged adjacent to each other in the horizontal direction, a horizontal collimating lens that condenses the laser light in the horizontal direction has a condensing portion (for example, a convex lens portion) corresponding to each light emitting region. It is necessary to install the provided lens. If the light emitting region arrangement density of the semiconductor laser array is increased, it is also necessary to increase the arrangement density of the corresponding condensing portions of the horizontal collimating lens. However, if it is intended to increase the arrangement density of the condensing portions, it is necessary to reduce the condensing portions accordingly. Therefore, it is difficult to manufacture a horizontal collimating lens. For this reason, there is a limit to improving the arrangement density of the condensing portions of the horizontal collimating lens, and this limit is also the limit for improving the arrangement density of the corresponding light emitting area. There was a problem that the density could not be improved.

  Accordingly, it is an object of the present invention to provide a semiconductor laser array that solves the above-described problems and can increase the arrangement density of the light emitting regions to improve the light density.

  In order to solve the above problems, a semiconductor laser array of the present invention is provided between a first conductivity type cladding layer, a second conductivity type cladding layer, and between the first conductivity type cladding layer and the second conductivity type cladding layer. A semiconductor laser array having a refractive index waveguide formed in the active layer, wherein the refractive index waveguide includes a reflection end surface located on a light reflection surface parallel to the light emitting surface, and a light An exit end face that is located on the exit face and is discontinuously formed in a region facing the reflection end face; and a pair of side surfaces that extend from the reflection end face to the exit end face to define a region in the longitudinal direction of the refractive index waveguide; The side surfaces are formed so as to totally reflect light incident from a direction perpendicular to the light emission surface from the light emission surface side toward the reflection end surface.

  According to the semiconductor laser array, the side surface of the refractive index waveguide totally reflects light incident from the light emitting surface side in a direction perpendicular to the light emitting surface toward the reflection end surface. Therefore, of the light generated in the refractive index waveguide, the light incident on the side surface from the direction perpendicular to the light exit surface is totally reflected on the side surface, reflected on the reflection end surface, and totally reflected on the other side surface and emitted. After being reflected at the end face, the optical path connecting the side face, the reflective end face, the other side face, and the exit end face can be reciprocated to resonate.

  On the other hand, since the exit end face is discontinuous at the position facing the reflection end face, there is no optical path connecting the reflection end face and the exit end face with a straight line perpendicular to both end faces, and the both end faces of the active layer are directly reciprocated. There is no light that resonates.

  As described above, according to the semiconductor laser array, the optical path of the laser beam where resonance occurs can be limited due to the structure of the refractive index waveguide, so that the angular component of the laser oscillation light is limited, and the high-order transverse mode is limited. Is suppressed to a single transverse mode, and the horizontal diffusion angle of the emitted laser light can be reduced. As described above, according to the semiconductor laser array, since the light quality in the horizontal direction of the laser light is improved and the diffusion angle is small, a horizontal collimating lens for condensing the laser light in the horizontal direction becomes unnecessary. Therefore, it is not necessary to match the arrangement density of the light emitting area of the semiconductor laser array to the arrangement density limit of the condensing part of the horizontal collimating lens, the arrangement density of the light emitting area can be improved, and a large light output and high reliability can be obtained. be able to.

  Further, the semiconductor laser array of the present invention may be characterized in that the refractive index waveguide is provided so as to branch corresponding to the emission end face on the way from the reflection end face side to the emission end face side.

  The semiconductor laser array of the present invention includes a first conductivity type cladding layer, a second conductivity type cladding layer, an active layer provided between the first conductivity type cladding layer and the second conductivity type cladding layer, The first conductivity type cladding layer has a plurality of ridges arranged in parallel along the longitudinal direction, and the active layer is formed with a refractive index waveguide corresponding to the ridges In the array, the ridge portion is positioned on a plane including a light reflecting surface parallel to the light emitting surface, and on a plane including the light emitting surface, and is opposed to the first end surface. A second end surface formed discontinuously in the region, and a pair of side surfaces extending from the first end surface to the second end surface and defining the region in the longitudinal direction of the ridge portion, The side surface of the refractive index waveguide formed corresponding to the side surface is the light exit surface. Characterized in that it is formed so as to totally reflect respectively toward the reflective surface of the refractive index waveguide is formed corresponding to light incident from the direction perpendicular to the light exit surface to the first end surface from.

  According to the semiconductor laser array, when a current is injected into the ridge portion of the first cladding layer, the active layer region corresponding to the ridge portion becomes the active region. At this time, since the active layer has an effective refractive index difference due to the refractive index difference between the ridge portion and the outside thereof, the shape of the ridge portion in plan view (the ridge portion is viewed from the thickness direction of the first cladding layer). A refractive index waveguide having a shape along the shape) is formed. This refractive index waveguide has a reflecting surface at a position corresponding to the first end face of the ridge portion. In addition, a discontinuous reflection surface is provided at a position corresponding to the second end surface of the ridge portion. Further, the refractive index waveguide has a pair of side surfaces having a shape corresponding to the side surface of the ridge portion. This side surface functions as a reflecting surface due to the above effective refractive index difference.

  The side surface of the refractive index waveguide totally reflects light incident from the light emitting surface side in a direction perpendicular to the light emitting surface toward the reflecting surface at a position corresponding to the first end surface of the refractive index waveguide. It has become. Therefore, among the light generated in the refractive index waveguide, light incident on the side surface from the direction perpendicular to the light emitting surface from the reflecting surface side at the position corresponding to the second end surface is totally reflected on the side surface, and is reflected on the first end surface. Reflected by the reflecting surface at the corresponding position, totally reflected by the other side surface, reflected by the reflecting surface at the position corresponding to the second end surface, and further reflected by the reflecting surface at the position corresponding to the first end surface, The optical path connecting the other side surface and the reflecting surface at the position corresponding to the second end surface can be reciprocated to resonate.

  On the other hand, since the second end surface of the ridge portion is discontinuous at the position facing the first end surface, the reflection surface at the position corresponding to the first end surface and the reflection surface at the position corresponding to the second end surface are both reflected. There is no optical path connecting with a straight line perpendicular to the surface, and there is no light that resonates directly by reciprocating both end faces of the active layer.

  As described above, according to the semiconductor laser array, the optical path of the laser beam where resonance occurs can be limited due to the structure of the refractive index waveguide, so that the angular component of the laser oscillation light is limited, and the high-order transverse mode is limited. Is suppressed to be close to a single mode, and the horizontal diffusion angle of the emitted laser light can be reduced. As described above, according to the semiconductor laser array, since the light quality in the horizontal direction of the laser light is improved and the diffusion angle is small, a horizontal collimating lens for condensing the laser light in the horizontal direction becomes unnecessary. Therefore, it is not necessary to match the arrangement density of the light emitting area of the semiconductor laser array to the arrangement density limit of the condensing part of the horizontal collimating lens, the arrangement density of the light emitting area can be improved, and a large light output and high reliability are obtained. be able to.

  Further, the semiconductor laser array of the present invention is characterized in that the ridge portion is provided so as to branch corresponding to the second end face in the middle from the first end face side to the second end face side. It is good.

  The semiconductor laser array of the present invention includes a first conductivity type cladding layer, a second conductivity type cladding layer, an active layer provided between the first conductivity type cladding layer and the second conductivity type cladding layer, A refractive index waveguide formed in the active layer, wherein the refractive index waveguide transmits laser light generated in the active layer from a spot on the light emitting surface parallel to the light emitting surface. The optical path to the spot on the light reflecting surface and the optical path from another spot on the light emitting surface to the spot on the light reflecting surface are reciprocated alternately to resonate.

  According to the semiconductor laser array, the transverse mode of laser oscillation is close to a single mode, and the horizontal diffusion angle of the laser light emitted from the light emitting surface can be reduced. As described above, according to the semiconductor laser array, since the diffusion angle of the laser beam is small, a horizontal collimating lens for condensing the laser beam in the horizontal direction becomes unnecessary. Therefore, it is not necessary to match the arrangement density of the light emitting area of the semiconductor laser array to the arrangement density limit of the condensing part of the horizontal collimating lens, the arrangement density of the light emitting area can be improved, and a large light output and high reliability can be obtained. be able to.

  According to the present invention, it is possible to provide a semiconductor laser array capable of increasing the arrangement density of the light emitting regions and improving the light density.

Embodiments of the present invention will be described below. In addition, the same code | symbol is used for the same element and the overlapping description is abbreviate | omitted.
(First embodiment)
A first embodiment of the present invention will be described with reference to FIG. 1, FIG. 2, and FIG. FIG. 1 is a schematic perspective view of a semiconductor laser array 1 according to this embodiment, FIG. 2 is a plan view of the semiconductor laser array 1, and FIG. 3 is a sectional view taken along line III-III. The semiconductor laser array 1 is a semiconductor device that generates laser light from the active layer 13 and emits the laser light from the light emitting region 5 arranged on the light emitting surface 4. The semiconductor laser array 1 is provided with V-shaped convex portions 2 on the surface, and a plurality of them are arranged in the longitudinal direction. The refractive index waveguide 3 is formed in the active layer 13 corresponding to the convex portion 2, and the light emitting region 5 is formed on the light emitting surface 4 corresponding to the convex portion 2. Thus, a plurality of refractive index waveguides 3 and light emitting regions 5 are arranged in the longitudinal direction corresponding to the convex portions 2.

  Hereinafter, the direction in which the laser beam is emitted is the z direction, the arrangement direction of the light emitting regions 5 is the x direction, and the direction perpendicular to both the z direction and the x direction is the y direction. z axis) is set and used for the following description.

  The semiconductor laser array 1 includes a stacked body 9 in which three semiconductor layers are stacked in the y direction on a substrate 7. The stacked body 9 is formed by stacking three semiconductor layers, a p-type cladding layer (first conductivity type cladding layer) 11, an active layer 13, and an n-type cladding layer (second conductivity type cladding layer) 15. The p-type cladding layer 11 is provided with a plurality of V-shaped ridge portions 23 arranged in the x direction. A cap layer 17 that is electrically connected to the p-type cladding layer 11 is provided on the outer layer of each ridge portion 23, and the ridge portion 23 and the cap layer 17 constitute the convex portion 2.

  Further, a p-side electrode layer 19 for injecting a current from the outside is provided on the outer layer. An insulating layer 21 is provided between the p-type cladding layer 11 and the cap layer 17 and the p-side electrode layer 19, and the insulating layer 21 has an opening at a portion corresponding to the convex portion of the cap layer 17. Yes. Since the p-side electrode layer 19 is in electrical contact only with the cap layer 17 at the opening, current injection from the outside is limited to the cap layer 17 only. An n-side electrode layer 18 is formed on the opposite side of the substrate 7 from the laminate 9. The substrate 7 is made of n-GaAs. The p-type cladding layer 11 is made of p-AlGaAs, the n-type cladding layer 15 is made of n-AlGaAs, and the active layer 13 is made of GaInAs / AlGaAs. The cap layer 17 is made of p-GaAs, the p-side electrode layer 19 is made of Ti / Pt / Au, the n-side electrode layer 18 is made of AuGe / Au, and the insulating layer 21 is made of SiN.

  The p-type cladding layer 11 will be described with reference to FIGS. 4 is a perspective view of the multilayer body 9 including the p-type cladding layer 11, FIG. 5A is a plan view of the multilayer body 9, FIG. 5B is a Vb-Vb sectional view of the multilayer body 9, and FIG. ) Is a Vc-Vc cross-sectional view thereof. As described above, the stacked body 9 is configured by stacking three semiconductor layers, the p-type cladding layer 11, the active layer 13, and the n-type cladding layer 15.

  The p-type cladding layer 11 is provided with a ridge portion 23 corresponding to the light emitting region 5, and the semiconductor laser array 1 has a so-called ridge structure. In a region other than the ridge portion 23 of the p-type cladding layer 11, a thin region 24 in which the layer is thinned is formed. The ridge portion 23 has a V-shape that is bifurcated from the position of the point G1 in the middle of the plan view shape from the light reflecting surface 6 to the light emitting surface 4. In other words, the cross-section of the ridge portion 23 in a plane (for example, Vb-Vb) that is parallel to the light emission surface 4 and closer to the light emission surface 4 than the point G1 is discontinuous as shown in FIG. The cross section of the ridge portion 23 on a plane (for example, Vc-Vc) on the light reflecting surface 6 side is a continuous shape as shown in FIG.

  The ridge portion 23 has a first end face 25, a discontinuous second end face 27, side faces 29a and 29b, inner side faces 31a, 31b, 33a and 33b, and the side faces 29a and 29b and inner side faces 31a, 31b and 33a. , 33b serve as a boundary surface between the ridge portion 23 and the thin region 24. The ridge portion 23 has a face-contrast shape with respect to a virtual plane G parallel to the zy plane. The first end surface 25 is on the light reflecting surface 6 facing the light emitting surface 4 in parallel. The second end surface 27 is on the light emitting surface 4, is formed in a discontinuous shape interrupted at a position 26 facing the first end surface 25, and is divided into second end surfaces 27 a and 27 b. At this time, the second end face only needs to be interrupted at least at the position 26 facing the first end face 25, and may be wider than the range as long as the interrupted range includes the range of the position 26. . A region where the second end surface 27 a and the second end surface 27 b are interrupted is a thin region 24.

  The side surface 29a extends from one end of the first end surface 25 to one end of the second end surface 27a, and the side surface 29b extends from the other end of the first end surface 25 to one end of the second end surface 27b. The side surfaces 29 a and 29 b each define a region in the y direction of the ridge portion 23 and serve as a boundary between the ridge portion 23 and the thin region 24. The side surfaces 29a and 29b are provided so as to form an angle θ with the light emitting surface 4 in a plan view seen from the y direction.

  A refractive index waveguide 3 corresponding to the shape of the ridge portion 23 is formed on the active layer 13, and a reflective surface 35 is formed on the refractive index waveguide 3 corresponding to the first end surface 25 of the ridge portion 23, and a side surface 29a. , 29b are formed corresponding to the reflecting surfaces 39a, 39b. The angle θ in the ridge portion 23 is such that the reflecting surfaces 39a and 39b of the refractive index waveguide 3 formed corresponding to the ridge portion 23 reflect light incident from the direction perpendicular to the z direction from the light emitting surface 4 side. It is set so as to be totally reflected toward 35. In other words, the side surfaces 29 a and 29 b of the ridge portion 23 are formed so as to form such reflecting surfaces 39 a and 39 b in the refractive index waveguide 3.

  The inner side surfaces 31a, 31b, 33a, 33b define the region of the ridge portion 23. The thin region 24 surrounded by the inner side surfaces 31a, 31b, 33a, 33b and the light emitting surface 4 is sandwiched between the first end surface 25 and a position on the light emitting surface 4 facing the first end surface 25. In the position. The thin region 24 discontinuously divides the side closer to the light emitting surface 4 than the point G1 of the ridge portion 23.

  For example, in the case of the semiconductor laser array 1, the length of the first end face 25 in the x direction is 40 μm, the length of the second end faces 27a and 27b in the x direction is 40 μm, and the discontinuous portion between the second end faces 27a and 27b. The length in the x direction is 50 μm and the angle θ is 85 °.

  A method for manufacturing the semiconductor laser array 1 will be described with reference to FIG. FIG. 6 shows a cross-sectional view of the semiconductor laser array 1 in each manufacturing process. First, an n-type GaAs substrate 7 is prepared, and n-type AlGaAs is grown to 2.0 μm, GaInAs / AlGaAs is 0.3 μm, p-type AlGaAs is 2.0 μm, and p-type GaAs is 0.1 μm. An n-type cladding layer 15, a quantum well active layer 13, a p-type cladding layer 11, and a cap layer 17 are formed (see FIG. 6A). Next, a protective mask is formed on the cap layer 17 side in a shape corresponding to the ridge portion 23 by a photowork, and the cap layer 17 and the p-type cladding layer 11 are etched. The etching stops at a depth that does not reach the active layer 13 (see FIG. 6B). Next, an SiN film is deposited on the entire crystal surface, and the SiN film at a position corresponding to the ridge portion 23 is removed by photowork to form an insulating layer 21 (see FIG. 6C). Further, a p-side electrode layer is formed as an upper layer with a Ti / Pt / Au film. Next, the surface on the substrate 7 side is polished and chemically treated to form an n-side electrode layer 18 of AuGe / Au (see FIG. 6D).

  The operation of the semiconductor laser array 1 during current injection will be described. The current is injected into each ridge portion 23 through the cap layer 17 (see FIG. 3). When current is injected into the ridge portion 23, the ridge portion of the semiconductor laser array 1 and other portions partitioned by the ridge portion 23 and the side surfaces 29a and 29b, and the inner side surfaces 31a, 31b, 33a, and 33b depending on the ridge structure. The refractive index waveguide 3 is formed in the active layer 13 due to the difference in the refractive index from the above region. The refractive index waveguide 3 is formed in a region of the active layer 13 corresponding to each ridge portion 23 due to the difference in refractive index, and is formed in a shape along the shape of the ridge portion 23. As a result, the refractive index waveguide 3 of the semiconductor laser array 1 has a V-shaped structure in which the shape in plan view (the shape viewed from the y direction) is bifurcated, and the laser light generated in the active layer 13 Is confined in the refractive index waveguide 3.

  FIG. 7 is a perspective view showing the shape of the refractive index waveguide 3 formed corresponding to each ridge portion 23. The refractive index waveguide 3 has the same shape as the ridge portion 23 in plan view. The refractive index waveguide 3 is defined by a boundary surface between the active layer 13 and the p-type cladding layer 11 and a boundary surface between the active layer 13 and the n-type cladding layer 15 in the y direction. The refractive index waveguide 3 has reflection surfaces (emission end surfaces) 37a and 37b at positions corresponding to the second end surfaces 27a and 27b of the ridge portion 23. The refractive index waveguide 3 has reflection surfaces 39 a and 39 b at positions corresponding to the side surfaces 29 a and 29 b of the ridge portion 23 and a reflection surface 35 at a position corresponding to the first end face 25. The refractive index waveguide 3 has inner side surfaces 41a, 41b, 43a, and 43b at positions corresponding to the inner side surfaces 31a, 31b, 33a, and 33b of the ridge portion 23. These surfaces function as reflection surfaces that selectively transmit or reflect the laser light generated in the refractive index waveguide 3 depending on the incident angle to the reflection surface.

  FIG. 8 is a plan view of the refractive index waveguide 3 as seen from the y direction. The reflection surfaces 37a and 37b are a part of the cleavage surface of the active layer 13, and are formed at positions corresponding to the second end surfaces 27a and 27b in the ridge portion 23, a reflection surface that reflects a part of the laser light, and the laser light The other part functions as the light emitting region 5 that emits the light to the outside.

  Due to the ridge structure of the semiconductor laser array 1, an effective refractive index difference is generated between the outside and the inside of the reflecting surfaces 39 a and 39 b of the refractive index waveguide 3. As described above, the reflecting surfaces 39 a and 39 b are formed at positions corresponding to the side surfaces 29 a and 29 b of the ridge portion 23, and laser light incident in the direction parallel to the z direction from the refractive index waveguide 3 is applied to the reflecting surface 35. It is formed at an angle for total reflection.

  As shown in FIG. 8, the laser beam L1 incident on the reflecting surface 39a in a direction parallel to the z axis is totally reflected as the laser beam L2. The laser beam L2 is reflected as L3 on the reflecting surface 35, and part of the laser beam L2 is transmitted through the reflecting surface 35 and emitted to the outside as the laser beam L11. Because of the symmetry of the shape of the refractive index waveguide 3, the laser beam L3 is incident on the reflecting surface 39b at the same incident angle as L1, and is totally reflected as the laser beam L4 toward the reflecting surface 37b. Since the laser beam L4 is perpendicularly incident on the reflecting surface 37b, it is reflected in the opposite direction as the laser beam L5 by the reflecting surface 37b. A part of the laser beam L5 passes through the reflecting surface 37b and is emitted to the outside as the laser beam L12. The laser beam L5 travels in exactly the opposite direction along the optical path of the laser beam L4, and is totally reflected by the reflecting surface 39b as the laser beam L6. The laser beam L6 is reflected by the reflecting surface 35 as the laser beam L7, and part of the reflecting surface. 35 is emitted to the outside as laser light L13. The laser beam L7 is totally reflected by the reflecting surface 39a to become a laser beam L8. The laser beam L8 is reflected in the opposite direction by the reflecting surface 37a to become the laser beam L9, and part of the laser beam L8 passes through the reflecting surface 37a and is emitted to the outside as the laser beam L14. Since the laser beam L9 is on the same optical path as the laser beam L1, the laser beam L9 travels again through the optical paths of the laser beams L1 to L9, and then, eventually, the reflecting surface 37a, the reflecting surface 35, the reflecting surface 37b, and the reflecting surface 35. Then, the light travels back and forth along the same optical path in the order of the reflection surface 37a.

  As described above, the reflection surfaces 37 a and 37 b emit the laser beams L 14 and L 12, respectively, and the reflection surfaces 37 a and 37 b correspond to the light emitting region 5. That is, one refractive index waveguide 3 is formed corresponding to one ridge portion 23, and two light emitting regions 5 that emit laser light are formed corresponding to one refractive index waveguide 3. The reflecting surface 35 also emits the laser beams L11 and L13 in different emission directions.

  As described above, the semiconductor laser array 1 transmits laser light incident on the reflecting surface 39a perpendicular to the z-axis from the light generated in the refractive index waveguide 3 from the reflecting surface 37a (spot on the light emitting surface). The optical path to the reflecting surface 35 (spot on the light reflecting surface) and the optical path from the reflecting surface 37b (another spot on the light emitting surface) to the reflecting surface 35 (spot on the light reflecting surface) are alternately reciprocated. And a resonator structure for resonating.

  On the other hand, FIGS. 9A, 9B, and 9C show examples of laser light incident on the reflecting surface 39a at an angle greatly deviated from the z-axis direction. 9A shows an example in which the laser beam L22 is incident on the reflecting surface 39a at an angle deeper than the total reflection angle and is transmitted through the reflecting surface 39a. The laser beam L21 in FIG. 9B is incident on the reflecting surface 39a at a shallower angle than the laser beam L1 in FIG. 8, and eventually enters the reflecting surface 39b at an angle deeper than the total reflection angle. The example which permeate | transmits is shown. 9C shows an example in which the laser beam L23 is incident at an angle deeper than the laser beam L1 in FIG. 8 and within the range of the total reflection angle and eventually passes through the reflecting surface 39b. As described above, a laser beam incident on the reflecting surface 39a at an angle greatly deviated from the z-axis direction cannot form a reciprocal optical path and cannot resonate.

  Further, since the reflecting surfaces 37a and 37b are interrupted at a position facing the reflecting surface 35, there is no optical path connecting the reflecting surface 37a or 37b and the reflecting surface 35 with a straight line perpendicular to both reflecting surfaces. There is no light that resonates directly between the reflecting surface 37a or 37b and the reflecting surface 35.

  As described above, in the semiconductor laser array 1, the optical path for the laser light generated in the refractive index waveguide 3 to reciprocate and resonate is from the optical path from the reflective surface 37a to the reflective surface 35 and from the reflective surface 37b. The structure is limited to an optical path that alternately reciprocates with the optical path to the reflecting surface 35. Therefore, only laser light that enters the reflecting surfaces 39a and 39b from a direction substantially parallel to the z-axis and resonates in the limited optical path described above contributes to laser oscillation. Therefore, laser oscillation (single spatial transverse mode) in which the angular component of the laser light is limited and the spatial transverse mode is single is obtained, and the intensity distribution of the laser light emitted from the light emitting region 5 is near the direction parallel to the z axis. Therefore, a laser beam having a small directional diffusion angle can be obtained.

  A far-field image obtained by the semiconductor laser array 1 is shown in FIG. FIG. 10A shows a far-field image in the x direction of the laser light emitted from the light emitting surface 4 side. As shown in FIG. 10A, the laser light emitted from the light emitting surface 4 side has an intensity distribution biased in a direction (0 °) parallel to the z axis, and the diffusion angle in the x direction is small. . According to FIG. 10A, the half width of the peak is about 2 °. Further, the current-light output characteristics of the semiconductor laser array 1 are shown in FIG. According to FIG. 11, since the current supplied to the semiconductor laser array 1 and the optical output show a linear correlation, it can be seen that a stable spatial transverse single mode is obtained in the semiconductor laser array 1. . Further, FIG. 10B shows a far-field image of the laser light obtained from the light reflecting surface 6 side. As can be seen from the figure, two narrow peaks are emitted symmetrically with respect to the z axis with a declination. This indicates that the optical path in the waveguide follows the path shown in FIG.

  According to the semiconductor laser array 1, since a laser beam having a small diffusion angle in the x direction can be obtained, a horizontal collimating lens for condensing in the x direction when mounted on a semiconductor laser device becomes unnecessary. Therefore, in the semiconductor laser array 1, it is not necessary to match the arrangement density of the light emitting areas to the arrangement density limit of the condensing portions of the horizontal collimating lens, and the arrangement density of the light emitting areas can be improved.

Further, as shown in FIG. 12, the semiconductor laser array 1 has an optical path for reciprocating a wide range (for example, L21 to L23) of laser beams parallel to the z axis. For this reason, the semiconductor laser array 1 has a long length in the x direction of the light emitting region 5 as a semiconductor laser array capable of obtaining a spatial transverse single mode, and can obtain a high output.
(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIGS. 13, 14, and 15. FIG. FIG. 13 is a perspective view showing the structure of the semiconductor laser array 61 according to this embodiment. 14 is a cross-sectional view of the semiconductor laser array 61 taken along the line XIV-XIV in FIG. 13 in parallel to the xy plane. FIG. 15 is a cross-sectional view of the semiconductor laser array 61 cut along the line XV-XV in FIG. 13 in parallel with the xz plane.

  An n-type block layer 65 made of an n-type semiconductor AlGaAs is buried in the p-type cladding layer 11 of the semiconductor laser array 61 as shown in FIG. The n-type block layer 65 has a lower refractive index than the p-type cladding layer 11. A region of the p-type cladding layer 11 other than the region where the n-type block layer 65 is embedded (hereinafter referred to as “non-embedded region”) 67 has the same planar shape as the ridge portion 23 of the semiconductor laser array 1 ( FIG. 15). In other words, the n-type block layer 65 is embedded in the p-type cladding layer 11 so that the non-embedded region 67 has the same planar view shape as the ridge portion 23.

  In the semiconductor laser array 61, a refractive index waveguide 63 having a shape in plan view similar to that of the non-embedded region 67 is formed in the active layer 13 due to the refractive index difference between the n-type block layer 65 and the p-type cladding layer 11. The However, the value of the angle θ is changed again according to the refractive index of the active layer inside and outside the waveguide so that the reflection surfaces 39a and 39b of the refractive index waveguide 3 to be formed totally reflect the laser light incident from the z-axis direction. It is necessary to set. Therefore, according to the semiconductor laser array 61, the refractive index waveguide 63 having the same configuration as that of the refractive index waveguide 3 of the semiconductor laser array 1 is formed, and the same operation and effect as the semiconductor laser array 1 described above can be obtained. Can do.

  The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, in the semiconductor laser array 1 described above, a layer is not provided in a portion corresponding to the thin region 24, but a portion corresponding to the thin region 24 as in the semiconductor laser array 51 whose sectional view is shown in FIG. Alternatively, a buried layer 53 having a refractive index lower than that of the p-type cladding layer 11 may be buried to form a so-called buried ridge structure. However, in this case, the angle θ is set again according to the refractive index of the buried layer 53 so that the reflection surfaces 39a and 39b of the refractive index waveguide 3 to be formed totally reflect the laser light incident from the z-axis direction. It is necessary to set.

  In the semiconductor laser array 1 described above, a ridge type refractive index waveguide is formed by providing a ridge portion 23 in the p-type cladding layer 11 to form a ridge structure. In the semiconductor laser array 61, a so-called planar refractive index waveguide is formed by embedding an n-type block layer having a low refractive index in a p-type cladding layer. However, the present invention is not limited to these, and can be applied to all semiconductor laser arrays having a refractive index waveguide structure.

1 is a schematic perspective view of a semiconductor laser array according to an embodiment. It is a top view of the semiconductor laser array concerning an embodiment. It is III-III sectional drawing of the semiconductor laser array which concerns on embodiment. It is a perspective view of the laminated body containing a p-type cladding layer. (A) is a top view of a laminated body, (b) is Vb-Vb sectional drawing of a laminated body, (c) is Vc-Vc sectional drawing of a laminated body. It is a figure explaining the manufacturing process of a semiconductor laser array. It is a perspective view which shows the shape of a refractive index waveguide. It is a top view which shows the shape of a refractive index waveguide. (A), (b), (c) is a figure explaining the optical path of the laser beam generate | occur | produced in the refractive index waveguide. (A) shows the far field image about the x direction of the laser beam radiate | emitted from the light-projection surface side. (B) shows the far field image about the x direction of the laser beam radiate | emitted from the light reflection surface side. It is the graph which showed the electric current-light output characteristic of a semiconductor laser array. It is a figure explaining the optical path of the laser beam generated in the refractive index waveguide. It is a perspective view which shows the structure of the semiconductor laser array which concerns on embodiment. It is sectional drawing which cut | disconnected the semiconductor laser array in parallel with xy plane along line XIV-XIV. It is sectional drawing which cut | disconnected the semiconductor laser array parallel to xz plane along line XV-XV. It is sectional drawing which shows the modification of a semiconductor laser array.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Semiconductor laser array, 3 ... Refractive index waveguide, 4 ... Light emission surface, 5 ... Light emission area, 6 ... Light reflection surface, 11 ... p-type cladding layer, 13 ... Active layer, 15 ... n-type cladding layer, 23 ... Ridge part, 25 ... 1st end surface, 27 ... 2nd end surface, 29 ... Side surface, 35, 37a, 37b, 39a, 39b ... Reflecting surface.

Claims (5)

A first conductivity type cladding layer; a second conductivity type cladding layer; and an active layer provided between the first conductivity type cladding layer and the second conductivity type cladding layer. A semiconductor laser array in which a refractive index waveguide is formed,
The refractive index waveguide is:
A reflection end surface located on a light reflection surface parallel to the light emission surface;
An exit end face located on the light exit face and formed discontinuously in a region facing the reflection end face;
A pair of side surfaces extending from the reflection end surface to the emission end surface and defining a region in the longitudinal direction of the refractive index waveguide;
The side surface
A semiconductor laser array, wherein light incident from a direction perpendicular to the light emission surface from the light emission surface side is totally reflected toward the reflection end surface. The refractive index waveguide is:
2. The semiconductor laser array according to claim 1, wherein the semiconductor laser array is provided so as to branch corresponding to the emission end face on the way from the reflection end face side to the emission end face side. A first conductivity type cladding layer; a second conductivity type cladding layer; and an active layer provided between the first conductivity type cladding layer and the second conductivity type cladding layer. The clad layer has a plurality of ridge portions arranged in parallel along the longitudinal direction, and the active layer is a semiconductor laser array in which a refractive index waveguide is formed corresponding to the ridge portion,
The ridge portion is
A first end surface located on a plane including a light reflecting surface parallel to the light emitting surface;
A second end surface located on a plane including the light exit surface and formed discontinuously in a region facing the first end surface;
A pair of side surfaces extending from the first end surface to the second end surface and defining a region in the longitudinal direction of the ridge portion;
The side surface of the ridge portion is
The side surface of the refractive index waveguide formed corresponding to the side surface is formed corresponding to the first end surface with light incident from the light emitting surface side in a direction perpendicular to the light emitting surface. A semiconductor laser array formed so as to be totally reflected toward the reflecting surface of the refractive index waveguide. The ridge portion is
4. The semiconductor laser array according to claim 3, wherein the semiconductor laser array is provided so as to branch corresponding to the second end face on the way from the first end face side to the second end face side. A first conductivity type cladding layer; a second conductivity type cladding layer; and an active layer provided between the first conductivity type cladding layer and the second conductivity type cladding layer. A semiconductor laser array in which a refractive index waveguide is formed,
The refractive index waveguide is configured to transmit laser light generated in the active layer from a spot on a light exit surface to a spot on a light reflection surface parallel to the light exit surface, and another on the light exit surface. A semiconductor laser array, wherein a light path from a spot to a spot on the light reflecting surface is reciprocated alternately to resonate.

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