JP2006093614A - Semiconductor laser element and semiconductor laser element array - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor laser element and a semiconductor laser element array which can reduce a difference in width between a reflecting end side and a light exit end side of a waveguide of a flare structure. <P>SOLUTION: A waveguide 4 has a mode selector 4a for limiting a spatial transverse mode of waveguiding light and a flare 4b whose width is expanded toward a laser light exit end 4e. Side surfaces 4g and 4h of the mode selector 4a have a relative angle θ<SB>1</SB>based on a total reflection critical angel θ<SB>c</SB>of the side surfaces 4g and 4h with respect to a light exit surface 1a and a light reflecting surface 1b. With it, since an optical path of laser light L resonating within the mode selector 4a is limited only to an optical path totally reflected by the side surfaces 4g and 4h, the laser light L has a spatial transversal single mode. Thus, the width of the mode selector 4a is not limited, and a difference between the width (corresponding to the width of the mode selector 4a) of a laser light reflecting end 4f side and the width (corresponding to the maximum width of the flare 4b) of a laser light exit end 4e side can be reduced. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  As a structure for reducing the radiation angle of laser light from a semiconductor laser element, a spatial transverse single mode structure has been conventionally known. In this single mode type semiconductor laser device, the width of the waveguide is set narrow in order to limit the oscillation mode in the waveguide to only a single mode (spatial transverse fundamental mode). However, when the width of the waveguide is narrow, the area of the emission end is also reduced. Further, when the laser light density becomes excessive at the emission end, the reliability of the semiconductor laser element is affected. Therefore, it is difficult to achieve a high output in a single mode semiconductor laser device having a narrow waveguide width.

  In order to solve this problem, semiconductor laser elements having a structure in which the waveguide width is expanded toward the emission end (hereinafter referred to as flare structure) have been developed (see, for example, Patent Documents 1 to 3). In a semiconductor laser element having a general flare structure, the width of the reflection end side of the waveguide is narrow so that the oscillation mode in the waveguide is limited to a single mode. And the width | variety by the side of the output end of a waveguide is formed widely so that the laser beam density in an output end may not become excessive also at the time of high output. Laser light limited to a single mode on the reflection end side of the waveguide propagates in the waveguide while being spread in the horizontal direction toward the emission end, and is emitted.

Japanese Patent Laid-Open No. 08-023133 JP 2000-200094 A US Pat. No. 4,860,017

  However, in the conventional semiconductor laser device having a flare structure, the width of the reflection end side of the waveguide is satisfied in order to satisfy both the single mode oscillation in the waveguide and the suppression of the laser light density at the emission end of the waveguide. Needs to be extremely narrow compared to the width on the exit end side. For example, as described in the literature, the waveguide width of the semiconductor laser diode of Patent Document 1 is 4 μm on the reflection end side and 100 μm on the emission end side. Thus, if the width of the waveguide is greatly different at both ends, it is necessary to form both ends of the waveguide in separate steps in the manufacturing process in order to ensure the dimensional accuracy of the waveguide width. Therefore, the manufacturing process becomes complicated and the yield of products decreases.

  The present invention has been made in view of the above points, and provides a semiconductor laser element and a semiconductor laser element array that can alleviate the difference between the width of the reflection end side and the emission end side of the waveguide in the flare structure. For the purpose.

  In order to solve the above problems, a semiconductor laser device according to 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 light emitting surface and a light reflecting surface which are provided side by side in a predetermined axial direction and are opposed to each other, and a waveguide which is formed in the active layer and reaches the light reflecting surface and the light emitting surface. The waveguide has a mode selection section and a flare section positioned on the light emission surface side with respect to the mode selection section, and the relative angle θ between the side surface, the light emission surface, and the light reflection surface in the mode selection section is Based on the total reflection critical angle θc at the side surface, the width of the flare portion in the direction intersecting the predetermined axial direction is increased toward the light emitting surface.

  In the semiconductor laser device, the relative angle θ between the side surface of the mode selection portion of the waveguide, the light emitting surface, and the light reflecting surface is based on the total reflection critical angle θc on the side surface. As a result, light incident on the side surface of the mode selection unit at an incident angle smaller than the total reflection critical angle θc passes through the side surface and exits from the waveguide. Therefore, the optical path of the light resonating in the waveguide is limited to an optical path that is incident on the side surface of the mode selection unit at an incident angle equal to or greater than the total reflection critical angle θc and is reflected substantially perpendicularly on the light exit surface and the light reflection surface. Is done. As described above, the optical path of the laser light that causes resonance is limited due to the structure of the waveguide, so that the angle component of the light related to the laser oscillation in the waveguide is limited. For this reason, the phases of the guided light are aligned, and oscillation in a single mode or near a single mode occurs.

  According to this semiconductor laser device, since the single mode oscillation in the waveguide is realized by devising the angle of the side surface of the mode selection section as described above, the width of the mode selection section is not limited. Therefore, the difference between the width on the reflection end side of the waveguide in the flare structure (that is, the width of the mode selection portion) and the width on the emission end side (width on the emission end side of the flare portion) can be reduced, and the manufacturing process can be reduced. It can be simplified.

  In addition, the semiconductor laser element may be characterized in that the pair of side surfaces in the flare portion are substantially equiangular with respect to the light emitting surface inside the waveguide. Since the pair of side surfaces of the flare section has such a configuration, the laser light traveling from the mode selection section to the flare section travels in the flare section symmetrically in the lateral direction. A mode close to single can be suitably maintained in the flare portion.

  In addition, the length of the mode selection unit and the length of the mode selection unit are such that the light resonating in the waveguide between the light emitting surface and the light reflection surface is reflected the same number of times on each of the pair of side surfaces of the mode selection unit. An interval between the pair of side surfaces of the mode selection unit may be set. In this way, the resonating light is reflected (total reflection) the same number of times on each of the pair of side surfaces of the mode selection unit, so that the resonating light is along the predetermined axial direction on both the light reflecting surface and the light emitting surface. The incident / reflection can be suitably performed. Further, by causing the resonating light to be totally reflected at least once each on the pair of side surfaces of the mode selection unit, it is possible to suppress the generation of an optical path that connects the light emission surface and the light reflection surface in a straight line in the mode selection unit. Therefore, according to this semiconductor laser element, the optical path of the laser light in the waveguide can be suitably limited.

  Further, the semiconductor laser element may be characterized in that a relative angle θ between the side surface of the mode selection unit, the light emitting surface, and the light reflecting surface is in a range of θc ≦ θ ≦ θc + 1 °. Thereby, the optical path of the resonating laser beam can be suitably limited, so that laser oscillation closer to a single mode can be obtained.

  In addition, the semiconductor laser element may be characterized in that the relative angle θ between the side surface of the mode selection unit and the light emitting surface and the light reflection surface substantially coincides with the total reflection critical angle θc on the side surface of the mode selection unit. . As a result, the laser oscillation mode can be made almost single.

  A semiconductor laser element array according to the present invention includes a plurality of any of the semiconductor laser elements described above, and the plurality of semiconductor laser elements are arranged side by side in a direction intersecting a predetermined axial direction. Features. According to this semiconductor laser element array, by providing a plurality of any of the semiconductor laser elements described above, it is possible to emit a laser beam having a high intensity, and the width of the reflection end side and the width of the emission end side of the waveguide in the flare structure The manufacturing process can be simplified.

  According to the semiconductor laser element and the semiconductor laser element array of the present invention, the difference between the width on the reflection end side and the width on the emission end side of the waveguide in the flare structure can be alleviated.

  Embodiments of a semiconductor laser device and a semiconductor laser device array according to the present invention will be described below in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)
FIG. 1 is a schematic perspective view showing a configuration of a first embodiment of a semiconductor laser element array according to the present invention. Referring to FIG. 1, a semiconductor laser element array 1 is formed by integrally forming a plurality of semiconductor laser elements 3. The number of semiconductor laser elements 3 provided in the semiconductor laser element array 1 may be any number. When only one semiconductor laser element 3 is provided, a single semiconductor laser element is used instead of the array. The semiconductor laser element array 1 includes a light emitting surface 1a and a light reflecting surface 1b that are provided side by side in the direction of a predetermined axis A and face each other. In the present embodiment, the light emitting surface 1a and the light reflecting surface 1b are provided substantially parallel to each other, and each intersects a predetermined axis A substantially perpendicularly. On the light emitting surface 1a, laser light emitting ends 4e of the plurality of semiconductor laser elements 3 are arranged side by side in the horizontal direction. Each of the plurality of semiconductor laser elements 3 has a convex portion 25a formed in a ridge shape. The convex portion 25a is provided so that the longitudinal direction thereof is inclined with respect to the light emitting surface 1a and the light reflecting surface 1b. The semiconductor laser element 3 has a refractive index type waveguide corresponding to the convex portion 25a. (Described later) is formed. The laser light emitting end 4e is a resonance end face where the laser light resonates in this waveguide, and the laser light is emitted from this end face. The plurality of semiconductor laser elements 3 are arranged side by side in the direction intersecting the longitudinal direction of the convex portion 25a and are integrally formed.

  The semiconductor laser element array 1 further has a convex portion 25b. The convex portion 25 b is formed along the light emitting surface 1 a over the plurality of semiconductor laser elements 3. One side surface of the convex portion 25b is a light emitting surface 1a. The convex portion 25b is connected to the end of the convex portion 25a on the light emitting surface 1a side, and is formed integrally with each convex portion 25a.

  FIG. 2A is a cross-sectional view showing a part of the II cross section of the semiconductor laser element array 1 shown in FIG. FIG. 2B is a cross-sectional view showing a part of the II-II cross section of the semiconductor laser element array 1 shown in FIG. 2A and 2B, the semiconductor laser element 3 constituting the semiconductor laser element array 1 includes a substrate 11 and a stacked body 12 in which three semiconductor layers are stacked. . The stacked body 12 is configured by sequentially stacking three semiconductor layers of an n-type cladding layer (second conductivity type cladding layer) 13, an active layer 15, and a p-type cladding layer (first conductivity type cladding layer) 17. Yes. The p-type cladding layer 17 is provided with a ridge portion 9a corresponding to the convex portion 25a and a hill-shaped portion 9b corresponding to the convex portion 25b. A p-type cap layer 19 that is electrically connected to the p-type cladding layer 17 is provided on the outer layer of the ridge portion 9a and the hill-shaped portion 9b. The ridge portion 9a and the p-type cap layer 19 constitute a convex portion 25a, and the hill portion 9b and the p-type cap layer 19 constitute a convex portion 25b.

  Furthermore, a p-side electrode layer 23 for injecting an external current is provided on the outer layer. An insulating layer 21 is provided between the p-type cladding layer 17 and the p-type cap layer 19 and the p-side electrode layer 23. The insulating layer 21 has an opening 21a. A part of the opening 21a is formed in a portion corresponding to the convex portion 25a. The other part of the opening 21a is formed in a region of the convex portion 25b that reaches the light emitting surface 1a from one end of the convex portion 25a. In addition, an n-side electrode layer 29 is formed on the surface of the substrate 11 opposite to the stacked body 12.

  Since the p-side electrode layer 23 is in electrical contact only with the p-type cap layer 19 through the opening 21 a, current injection from the outside corresponds to the opening 21 a of the p-type cap layer 19. This is done only in the area to be performed. When current is injected into the p-type cap layer 19, the region of the active layer 15 corresponding to the opening 21a becomes the active region. In the portion corresponding to the ridge portion 9a in the active region, an effective refractive index difference is generated in the active layer 15 due to the refractive index difference between the ridge portion 9a and the peripheral portion thereof. Therefore, the refractive index type waveguide portion 4a having a shape corresponding to the planar shape of the ridge portion 9a is generated in the active layer 15. As will be described later, the waveguide portion 4a has an action of selecting the spatial transverse mode of the laser light that resonates inside the waveguide. Therefore, the waveguide portion 4a is hereinafter referred to as a mode selection unit 4a.

  Further, the portion corresponding to the hill-shaped portion 9b in the active region has a shape corresponding to the planar shape of the opening 21a of the insulating layer 21 in the hill-shaped portion 9b due to current concentration immediately below the opening 21a of the insulating layer 21. A gain-type waveguide portion 4b is generated. As will be described later, the waveguide portion 4b has a planar shape enlarged toward the light emitting surface 1a (laser light emitting end 4e). Therefore, the waveguide portion 4b is hereinafter referred to as a flare portion 4b. The mode selection unit 4 a and the flare unit 4 b constitute the waveguide 4.

If the material of each layer which comprises the semiconductor laser element 3 is illustrated, the board | substrate 11 will consist of n-GaAs, for example. The n-type cladding layer 13 is made of, for example, n-AlGaAs. The active layer 15 is composed of, for example, a multiple quantum well made of GaInAs / AlGaAs. The p-type cladding layer 17 is made of, for example, p-AlGaAs. The p-type cap layer 19 is made of, for example, p-GaAs. The p-side electrode layer 23 is made of, for example, Ti / Pt / Au. The n-side electrode layer 29 is made of, for example, AuGe / Au. The insulating layer 21 is made of, for example, at least one material of SiN, SiO ₂ , and Al ₂ O ₃ .

  The semiconductor laser element 3 includes a light guide layer for confining light in the waveguide 4 between the active layer 15 and the n-type cladding layer 13 and between the active layer 15 and the p-type cladding layer 17. May be. When the semiconductor laser device 3 includes the light guide layer, the light guide layer may have the same conductivity type as that of the adjacent cladding layer, or an impurity that determines the conductivity type may not be added.

  Here, the p-type cladding layer 17 will be described with reference to FIGS. 3 and 4. 3 is a perspective view of the laminated body 12 including the p-type cladding layer 17, FIG. 4A is a plan view of the laminated body 12, and FIG. 4B is a cross-sectional view of the laminated body 12 shown in FIG. FIG. 4C is a cross-sectional view showing the IV-IV cross section of the laminate 12 shown in FIG. 4A. As described above, the stacked body 12 is configured by sequentially stacking three semiconductor layers of the n-type cladding layer 13, the active layer 15, and the p-type cladding layer 17.

A convex ridge portion 9 a is formed on the p-type cladding layer 17. Further, the p-type cladding layer 17 is formed with a hill-shaped portion 9b that is thicker than other regions (excluding the ridge portion 9a) in the p-type cladding layer 17. A region of the p-type cladding layer 17 other than the ridge portion 9a and the hill portion 9b is a thin portion 10 that is thinner than the ridge portion 9a and the hill portion 9b. The ridge portion 9a has an end surface 9f and a pair of side surfaces 9g and 9h substantially parallel to each other. The pair of side surfaces 9g and 9h each define a region of the ridge portion 9a and is a boundary between the ridge portion 9a and the thin portion 10. The end surface 9f is on the light reflecting surface 1b. The side surface 9g extends from one end of the end surface 9f to the hill-shaped portion 9b, and the side surface 9h extends from the other end of the end surface 9f to the hill-shaped portion 9b. Side 9g and 9h, in plan view from the thickness direction, are provided so as to have the relative angle theta ₁ to the light emitting surface 1a and the light reflecting surface 1b. The hill 9b has a side surface 9u. A side surface of the hill portion 9b facing the side surface 9u is a light emitting surface 1a, and the side surface 9u extends along the light emitting surface 1a. The side surface 9u defines the region of the hill-shaped portion 9b and serves as a boundary between the hill-shaped portion 9b and the thin portion 10. One end of the side surfaces 9g and 9h of the ridge portion 9a is connected to the side surface 9u of the hill-shaped portion 9b.

An opening 21a of the insulating layer 21 is provided on the ridge 9a and the hill 9b. 3 and 4A, the insulating layer 21 is not shown, so the opening 21a is indicated by a dotted line. A part of the opening 21a extends along a region sandwiched between the side surfaces 9g and 9h of the ridge portion 9a. The other part of the opening 21a has a width in a direction intersecting the direction of the predetermined axis A toward the light emitting surface 1a in a region reaching the light emitting surface 1a from one end of the ridge portion 9a on the hill 9b. It is formed to expand. In the present embodiment, a pair of side surface of the opening 21a on the hill-like portion 9b is formed so as to form the same angle theta ₂ inside the opening 21a with respect to the light emitting surface 1a.

  In the active layer 15, the waveguide 4 (the mode selection unit 4a and the flare unit 4b) corresponding to the planar shape of the ridge portion 9a and the planar shape of the opening 21a of the insulating layer 21 in the hill portion 9b is generated. Here, FIG. 5 is a plan view of the waveguide 4 generated in the active layer 15. The waveguide 4 includes a mode selection unit 4a and a flare unit 4b. In the mode selection unit 4a, a laser beam reflection end 4f is generated corresponding to the end surface 9f of the ridge portion 9a. The mode selection unit 4a generates a pair of side surfaces 4g and 4h corresponding to the side surfaces 9g and 9h of the ridge portion 9a. The laser beam reflecting end 4 f is a part of the cleavage surface of the active layer 15 and functions as one resonance surface for the laser beam L. Further, the side surfaces 4g and 4h are surfaces generated by a difference in refractive index between the inside and outside of the mode selection unit 4a. When the refractive index continuously changes, each of them may have a certain thickness. . The side surfaces 4g and 4h function as reflection surfaces that selectively transmit or reflect the laser light L generated in the waveguide 4 according to the incident angle to the side surface.

Moreover, the flare part 4b is produced | generated by the light-projection surface 1a side with respect to the mode selection part 4a. In the flare portion 4b, a laser light emitting end 4e is generated corresponding to the end of the opening 21a on the light emitting surface 1a side. Further, in the flare portion 4b, a pair of side surfaces 4p and 4q are generated corresponding to the pair of side surfaces of the opening 21a. The laser beam emitting end 4 e is a part of the cleavage surface of the active layer 15 and functions as the other resonance surface for the laser beam L. Further, the side surfaces 4p and 4q are generated so that the flare portion 4b expands toward the laser light emitting end 4e in accordance with the shape of the side surface of the opening 21a of the insulating layer 21. In this embodiment, the side surface 4p and 4q and the laser beam emitting end 4e and (light emitting surface 1a) is so as to form the same angle theta ₂ to the inside of the flare portion 4b, the side surface 4p and 4q are generated.

Here, the relative angle θ ₁ between the side surfaces 4g and 4h of the mode selection unit 4a and the light emitting surface 1a and the light reflecting surface 1b (that is, the side surfaces 9g and 9h of the ridge portion 9a, the light emitting surface 1a and the light reflecting surface 1b) Relative angle θ ₁ ) is determined based on the total reflection critical angle θc at the side surfaces 4g and 4h of the mode selector 4a. Here, the total reflection critical angle θc at the side surfaces 4g and 4h of the mode selection unit 4a is a total reflection critical angle defined by an effective refractive index difference inside and outside the mode selection unit 4a which is a refractive index type waveguide.

By relative angle theta ₁ is determined based on the total reflection critical angle .theta.c, a pair of side surfaces 4g and 4h of the mode selection portion 4a, the direction of the predetermined axis A from the light emitting surface 1a side or the light reflecting surface 1b side The laser beam L incident along is totally reflected. In the present embodiment, the total reflection critical angle θc depends on the thickness of the thin portion 10 of the p-type cladding layer 17. Therefore, the total reflection critical angle θc at the side surfaces 4g and 4h is set to an arbitrary value by a method such as adjusting the thickness of the thin portion 10, for example.

As shown in FIG. 5, the laser beam L reflected substantially perpendicularly along the direction of the predetermined axis A at the laser light reflecting end 4f is incident at an incident angle theta ₁ to the side surface 4h of the mode selection unit 4a, the total reflection To do. Then, the laser beam L is incident at an incident angle theta ₁ to the side surface 4g, totally reflected. Thereafter, the laser light L travels along the direction of the predetermined axis A, reaches the laser light emitting end 4e through the flare portion 4b. At this time, since the width of the flare portion 4b is expanded toward the laser light emitting end 4e, the laser light L propagates in the flare portion 4b while being expanded in the horizontal direction due to the amplification action. A part of the laser light L reaching the laser light emitting end 4e is transmitted through the laser light emitting end 4e and emitted to the outside. The remaining laser light L1 is reflected substantially perpendicularly along the direction of the predetermined axis A at the laser light emitting end 4e, is totally reflected again by the side surfaces 4g and 4h, and returns to the laser light reflecting end 4f. In this way, the laser beam L reciprocates between the laser beam emitting end 4e and the laser beam reflecting end 4f and resonates.

As shown in FIG. 5, it is preferable that an AR coat 16 and an HR coat 18 are provided on the laser beam emitting end 4e and the laser beam reflecting end 4f of the waveguide 4, respectively. As an example of the dimensions of the waveguide 4, the width of the mode selection unit 4 a is 40 μm, the length of the mode selection unit 4 a is 1200 μm, and the side surfaces 4 g and 4 h are relative to the light emitting surface 1 a and the light reflecting surface 1 b. The angle θ ₁ can be 86 °. Further, the length of the flare portion 4b can be set to 430 μm, and the width of the laser beam emitting end 4e can be set to 100 μm.

Here, a mechanism in which the laser beam L is limited to the optical path described above will be described. FIG. 6 is a diagram for explaining light L1 to L3 incident on the side surface 4g (4h) at various incident angles θi. Referring to FIG. 6, the laser beam L1 incident on the side surface 4g (4h) at an incident angle θi equal to the relative angle θ ₁ (≧ θc) is totally reflected on the side surface 4g (4h), and the laser beam emitting end 4e (laser) Incident perpendicularly to the light reflecting end 4f) along the direction of the predetermined axis A. The laser light L1 is reflected at the laser light emitting end 4e (laser light reflecting end 4f) and then returns along the same optical path. Therefore, the laser beam L1 resonates on the same optical path.

In contrast, laser beam L2 incident at a small angle of incidence θi = θ ₁ -Δθ than relative angle theta ₁ to the side surfaces 4g (4h), when θ ₁ -Δθ is smaller than the total reflection critical angle .theta.c, side surfaces 4g (4h) is transmitted and does not resonate. The laser beam L3 incident on the side surface 4g (4h) at an incident angle θi = θ ₁ + Δθ larger than the relative angle θ ₁ has a larger incident angle θi than the total reflection critical angle θc, and thus the side surface 4g (4h). Although it is totally reflected, the incident angle θi becomes θi = θ ₁ −Δθ when it is incident again on the side surface 4g (4h) after being reflected at the laser light emitting end 4e (laser light reflecting end 4f). If the value of θ ₁ −Δθ is smaller than the total reflection critical angle θc, the laser beam L3 will eventually pass through the side surface 4g (4h) and will not resonate. As described above, in the mode selection unit 4a of the waveguide 4, when Δθ satisfies θ ₁ −Δθ ≧ θc, the light enters the side surfaces 4g and 4h at the incident angle θi (θ ₁ + Δθ ≧ θi ≧ θ ₁ −Δθ). Only the laser beam to resonate selectively resonates.

If the relative angle θ ₁ substantially coincides with the total reflection critical angle θc, Δθ described above can be made substantially zero, so that the angle component of the laser light L can be limited to a very narrow range. However, in practice, it is necessary to consider changes in the total reflection critical angle θc due to changes in the temperature of the element. If the relative angle theta ₁ is close to the total reflection critical angle θc at the total reflection critical angle θc is larger than the range, it is possible to some extent limit the angular component of the laser beam L. Here, FIG. 7 is a graph for explaining a range in which the magnitude of the relative angle θ ₁ is allowed. In FIG. 7, the horizontal axis is the magnitude of the relative angle θ ₁ , and the vertical axis is the difference θi−θ ₁ between the incident angle θi of the laser light L on the side surfaces 4 g and 4 h and the relative angle θ ₁ . Here, description will be made assuming that the total reflection critical angle θc at the side surfaces 4g and 4h is 86 °.

Referring to FIG. 7, a region B surrounded by coordinates (θ ₁ , θi−θ ₁ ) = (86, 0), (90, 0), (90, 4) is illustrated. This region B indicates a range in which the laser beam L can resonate between the laser beam emitting end 4e and the laser beam reflecting end 4f. For example, when the relative angle θ ₁ is 89 °, if the laser light L is 0 ° ≦ θi−θ ₁ ≦ 3 °, that is, the incident angle θi is 86 ° or more and 89 ° or less, the total reflection criticality is obtained at the side surfaces 4g and 4h. Resonance can be achieved without exceeding the angle θc (= 86 °). However, if the relative angle θ ₁ is larger than the total reflection critical angle θc, the number of spatial modes of the laser light L in the mode selection unit 4a increases. Therefore, for example, by setting the relative angle θ ₁ to 86 ° ≦ θ ₁ ≦ 87 ° (that is, θc ≦ θ ₁ ≦ θc + 1 °), 0 ° ≦ θi−θ ₁ ≦ 1 °, that is, the incident angle θi is 86 °. The angle can be limited to 87 ° or less, and the angle component of the laser beam L can be limited to a practically effective level.

  Thus, the angle component of the light related to laser oscillation in the waveguide 4 is limited by the side surfaces 4g and 4h of the mode selection unit 4a. For this reason, the phases of the guided light are aligned, and oscillation in a single mode or near a single mode occurs. Note that the length of the mode selection portion 4a and the distance between the side surfaces 4g and 4h (that is, the length of the ridge portion 9a and the distance between the pair of side surfaces 9g and 9h) are the laser light emission end 4e (light emission surface 1a). It is preferable that the laser beam L resonating between the laser beam reflecting end 4f (the light reflecting surface 1b) is reflected so as to be reflected the same number of times on each of the pair of side surfaces 4g and 4h of the mode selection unit 4a.

  In the semiconductor laser device 3 of the present embodiment, single mode oscillation in the waveguide 4 is realized by devising the angles of the side surfaces 4g and 4h of the mode selection unit 4a as described above. The width is not limited. Therefore, in the semiconductor laser device having the conventional flare structure, the width of the reflection end side of the waveguide (the ridge waveguide of the mode selection portion) is limited to a small width such as several μm, whereas the semiconductor laser device of the present embodiment 3, the width of the waveguide 4 on the laser light reflecting end 4 f side (that is, the width of the mode selection unit 4 a) can be several tens of μm or more. As described above, according to the semiconductor laser device 3 of the present embodiment, the difference between the width of the waveguide 4 on the laser light reflecting end 4f side and the width on the laser light emitting end 4e side (that is, the maximum width of the flare portion 4b). The manufacturing process can be simplified.

Further, in the semiconductor laser element 3 of the present embodiment, the width of the laser light emitting end 4e is widened by the flare portion 4b, so that the horizontal direction of the laser light L is higher than when the waveguide is composed of only the mode selection portion. The emission angle in the direction can be made narrower, and a laser beam having a higher intensity can be emitted. Here, FIG. 8 is a graph showing the results of observing the far-field image of the semiconductor laser device 3 of this embodiment as a prototype. In FIG. 8, the horizontal axis represents the horizontal radiation angle, and the vertical axis represents the laser light intensity. In this prototype, the length of the mode selection unit 4a is 1200 μm, the width of the mode selection unit 4a is 40 μm, and the relative angle θ ₁ between the side surfaces 4g and 4h of the mode selection unit 4a and the light emitting surface 1a and the light reflecting surface 1b is the side surface. The total reflection critical angle θc was about the same at 4 g and 4 h. In addition, the length of the flared portion 4b 1000 .mu.m, the relative angle theta ₂ between the side surface 4p and 4q and the light emitting surface 1a of the flared portion 4b and the 85 ° to 87 °. As shown in FIG. 8, the full width at half maximum of the fabricated semiconductor laser element 3 is suppressed to about 1.1 °. This value is about half that when the waveguide is composed of only the mode selection section. Thus, according to the semiconductor laser device 3 of the present embodiment, the horizontal emission angle of the laser light L can be made narrower.

  In addition, when the waveguide is composed only of the mode selection section, in order to increase the width of the laser light emitting end, the length of the waveguide (resonator length) needs to be increased according to the width of the laser light emitting end. is there. On the other hand, according to the semiconductor laser device 3 of the present embodiment, since the waveguide 4 has the flare portion 4b, the width of the laser light emitting end 4e is increased and the length of the waveguide 4 (resonator length). ) Can be kept short. Therefore, the semiconductor laser element array 1 (semiconductor laser element 3) can be reduced in size. In addition, since the optical loss inside the waveguide can be reduced, the light emission efficiency can be improved and the threshold current can be lowered.

  Further, the improvement of the light emission efficiency and the reduction of the threshold current in the semiconductor laser device 3 of the present embodiment become more remarkable by the action described below. This operation will be described with reference to FIGS. 9A and 9B. Fig.9 (a) is a top view which shows an example of the shape of the waveguide 4 of this embodiment. FIG. 9B is a plan view showing an example of a waveguide shape of a conventional flare type semiconductor laser element for comparison. As shown in FIG. 9A, in this embodiment, the width of the waveguide 4 on the laser light reflecting end 4f side (that is, the width of the mode selection unit 4a) can be set to a large value, for example, 40 μm. is there. On the other hand, as shown in FIG. 9B, in the conventional flare type semiconductor laser element, the width of the waveguide 104 on the laser light reflection end 104f side (that is, the width of the single mode waveguide portion 104a) is set to, for example, 2. It can only be set to a small value of 5 μm. In these examples, the waveguide width on the laser light emission end side is set to 100 μm for both the waveguide 4 of the present embodiment and the waveguide 104 of the conventional example.

  In each of the waveguides 4 and 104, since the laser oscillation is obtained by using the reflection at the laser light emitting ends 4e and 104e, the return light from the laser light emitting ends 4e and 104e to the inside of the waveguides 4 and 104 is obtained. La and Lb exist. Some of the return lights La and Lb return to the mode selection unit 4a and the single mode type waveguide portion 104a, respectively, and contribute to laser oscillation. Further, the remainder of the return lights La and Lb exits the waveguide from the side surfaces of the flare portions 4b and 104b, respectively, and do not contribute to laser oscillation. Since the width of the mode selection unit 4a of the present embodiment can be wider than the width of the conventional single mode type waveguide portion 104a (in this example, 40 μm / 2.5 μm = 16 times), the width of the waveguide 4 of the present embodiment According to the configuration, more return light La can contribute to laser oscillation. Accordingly, the gain of laser oscillation in the waveguide 4 is increased, so that the light emission efficiency can be further improved and the threshold current can be further reduced.

  Further, in the conventional flare-type waveguide 104, there is a problem that the spatial transverse mode is disturbed by scattering of the return light Lb from the side surface of the flare 104b, and the spatial transverse side mode (ripple) is generated in the far field image. . Moreover, in order to solve this, it was necessary to add a configuration for suppressing the spatial lateral mode, such as providing a light absorption region (radiation mode suppression region) outside the flare portion as in Patent Document 1, for example. . On the other hand, according to the semiconductor laser device 3 of the present embodiment, the side surfaces 4p and 4q of the flare portion 4b can be made extremely narrower than the side surface of the conventional flare portion 104b. The mode can be suppressed.

  In the semiconductor laser device 3 of the present embodiment, the width of the waveguide 4 on the laser light reflecting end 4f side can be made larger than that of the conventional flare type semiconductor laser device as described above. Therefore, the width of the laser beam reflecting end 4f is widened, and the laser beam density at the laser beam reflecting end 4f can be reduced. As a result, optical damage (COD: Catastrophic Optical Damage), which is the main cause of deterioration of the semiconductor laser element, can be suppressed even at the laser light reflecting end 4f, so that the reliability of the element is improved and stronger laser light is emitted. It becomes possible to emit light.

In the semiconductor laser device 3 of the present embodiment, it is preferable that the pair of side surfaces 4p and 4q in the flare portion 4b form a substantially equiangular angle (angle θ ₂ ) inside the waveguide 4 with respect to the light emitting surface 1a. . Since the pair of side surfaces 4p and 4q of the flare portion 4b has such a configuration, the laser light L that has traveled from the mode selection portion 4a to the flare portion 4b travels symmetrically in the lateral direction in the flare portion 4b. Therefore, the single or nearly single mode selected in the mode selection unit 4a can be suitably maintained in the flare unit 4b.

  In the semiconductor laser device 3 of the present embodiment, the laser light L that resonates in the waveguide 4 between the light emitting surface 1a and the light reflecting surface 1b is applied to each of the pair of side surfaces 4g and 4h of the mode selection unit 4a. It is preferable that the length of the mode selection unit 4a and the distance between the side surfaces are set so as to reflect the same number of times. Thereby, the laser beam L can be incident / reflected substantially perpendicularly along the direction of the predetermined axis A on both the light emitting surface 1a and the light reflecting surface 1b. Further, since the laser beam L is totally reflected at least once at the side surfaces 4g and 4h of the mode selection unit 4a, there is an optical path that connects the light emitting surface 1a and the light reflection surface 1b with a straight line in the mode selection unit 4a. do not do. Therefore, according to the semiconductor laser device 3 of the present embodiment, the optical path of the laser light L in the waveguide 4 can be suitably limited.

  In addition, according to the semiconductor laser element array 1 according to the present embodiment, by providing a plurality of semiconductor laser elements 3 having the above-described effects, it is possible to emit a laser beam having a large intensity and to transmit the laser light reflecting end of the waveguide 4. The difference between the width on the 4f side and the width on the laser light emitting end 4e side (that is, the maximum width of the flare portion 4b) can be reduced, and the manufacturing process can be simplified.

  Furthermore, the semiconductor laser device array 1 according to the present embodiment has the following effects. That is, in the semiconductor laser element array 1, current is partially concentrated and injected into the active layer 15 by the ridge portion 9 a of the p-type cladding layer 17. This makes it difficult for light coupling or interference between the waveguides 4 of the adjacent semiconductor laser elements 3 to occur. Therefore, since the interval between the waveguides 4 can be made relatively narrow, more waveguides 4 can be provided, and a stable laser beam can be emitted with a large output. Further, since the current is partially concentrated and injected into the active layer 15, the electrical / optical conversion efficiency is increased and the reactive current can be reduced, so that the heat generation of the semiconductor laser element 3 can be reduced. Therefore, the reliability of the semiconductor laser element array 1 is improved, and a long life can be realized.

  Next, a method for manufacturing the semiconductor laser element array 1 will be described with reference to FIGS. FIG. 10 shows an enlarged plan view of the semiconductor laser element array 1 in each manufacturing process. FIG. 11 is an enlarged cross-sectional view taken along the I-I cross section (see FIG. 1) of the semiconductor laser element array 1 in each manufacturing process. First, a substrate 11 made of n-type GaAs is prepared. On the substrate 11, n-type AlGaAs is 2.0 μm, GaInAs / AlGaAs is 0.3 μm, p-type AlGaAs is 2.0 μm, and p-type GaAs is 0.1 μm. Epitaxial growth is performed to form an n-type cladding layer 13, an active layer 15 having a quantum well structure, a p-type cladding layer 17, and a p-type cap layer 19, respectively (see FIGS. 10A and 11A).

  Subsequently, a protective mask 24 is formed on the p-type cap layer 19 side by a photo work in a shape corresponding to the ridge portion 9a and the hill-like portion 9b, and the p-type cap layer 19 and the p-type cladding layer 17 are etched. The etching stops at a depth that does not reach the active layer 15 (see FIGS. 10B and 11B). Subsequently, an SiN film is deposited on the entire crystal surface to form an insulating layer 21, and a part of the SiN film is removed by photowork to form an opening 21a (FIGS. 10C and 11C). reference). Subsequently, a p-side electrode layer 23 is formed on the entire crystal surface with a Ti / Pt / Au film. Further, polishing and chemical treatment of the surface on the substrate 11 side are performed, and an n-side electrode layer 29 is formed of AuGe / Au (see FIGS. 10D and 11D). Finally, AR coating is applied to the light emitting surface 1a, and HR coating is applied to the light reflecting surface 1b to complete the semiconductor laser element 3 (semiconductor laser element array 1).

(First modification)
Next, a first modification of the semiconductor laser element array 1 (semiconductor laser element 3) according to the first embodiment will be described. FIG. 12 is a plan view showing a waveguide 41 included in the semiconductor laser element 3a according to this modification. The difference between the semiconductor laser element 3a of the present modification and the semiconductor laser element 3 of the first embodiment is the planar shape of the mode selection unit 41a.

  The waveguide 41 of this modification has a mode selection part 41a and a flare part 41b. Among these, the planar shape of the flare part 41b is the same as the planar shape of the flare part 4b of the first embodiment described above. The mode selection unit 41a has a pair of side surfaces 41g and 41h substantially parallel to each other and a pair of side surfaces 41i and 41j substantially parallel to each other. One end of the mode selection section 41a is a laser beam reflection end 41f, and the other end is connected to the flare section 41b.

One end of the side surface 41i of the mode selection unit 41a is in contact with one end of the laser beam reflecting end 41f, and one end of the side surface 41j is in contact with the other end of the laser beam reflecting end 41f. The other end of the side surface 41i is connected to one end of the side surface 41g, and the other end of the side surface 41j is connected to one end of the side surface 41h. The other end of the side surface 41g is connected to the side surface 41p of the flare portion 41b, and the other end of the side surface 41h is connected to the side surface 41q of the flare portion 41b. Side 41g~41j mode selection unit 41a includes a relative angle theta ₁ with respect to the light emitting surface 1a and the light reflecting surface 1b. The side surfaces 41g and 41h and the side surfaces 41i and 41j are inclined in different directions with respect to the direction of the predetermined axis A. That has the side surface 41g and the side surface 41i connected at an angle [pi-2 [Theta] ₁ together, are connected at an angle [pi-2 [Theta] ₁ to each other between the side surface 41h and the side surface 41j. An auxiliary line C in the figure is an auxiliary line parallel to the light emitting surface 1a and the light reflecting surface 1b. Such a shape of the mode selection portion 41a is preferably realized by forming the planar shape of the ridge portion 9a of the p-type cladding layer 17 in the same manner as the planar shape of the mode selection portion 41a.

The relative angle θ ₁ between the side surfaces 41g to 41j of the mode selection unit 41a and the light emitting surface 1a and the light reflection surface 1b is determined based on the total reflection critical angle θc on the side surfaces 41g to 41j of the mode selection unit 41a. Thereby, the pair of side surfaces 41g and 41h and the pair of side surfaces 41i and 41j of the mode selection unit 41a are incident along the direction of the predetermined axis A from the light emitting surface 1a side or the light reflecting surface 1b side. Is totally reflected. The relative angle between the side surfaces 41g and 41h and the light emitting surface 1a and the light reflecting surface 1b in the present modification, and the relative angle between the side surfaces 41i and 41j and the light emitting surface 1a and the light reflecting surface 1b as the same angle theta ₁ However, the relative angles may be different from each other. In that case, the total reflection critical angle of the side surfaces 41g and 41h and the total reflection critical angle of the side surfaces 41i and 41j are different from each other. The relative angles between the side surfaces 41g to 41j and the light emitting surface 1a and the light reflecting surface 1b are individually determined based on the total reflection critical angles at the side surfaces 41g to 41j. The total reflection critical angle at the side surfaces 41g to 41j can be set to an arbitrary value by a method such as adjusting the thickness of the thin portion 10 of the p-type cladding layer 17, for example.

The laser beam L reflected substantially perpendicularly along the direction of the predetermined axis A at the laser light reflecting end 41f are incident at the incident angle theta ₁ to the side surface 41i of the mode selector 41a, totally reflected. Then, the laser beam L is incident at an incident angle theta ₁ to the side surface 41j, is totally reflected. The laser beam L travels along the direction of the predetermined axis A, at an incident angle theta ₁ to the side surface 41h, is totally reflected. Then, the laser beam L is incident at an incident angle theta ₁ to the side surface 41 g, to total reflection. Thus, the laser beam L totally reflected by the side surfaces 41g to 41j travels along the direction of the predetermined axis A, is amplified in the flare portion 41b, and reaches the laser beam emitting end 41e. A part of the laser beam L reaching the laser beam emitting end 41e is transmitted through the laser beam emitting end 41e and emitted to the outside. The other laser light L is reflected substantially perpendicularly along the direction of the predetermined axis A at the laser light emitting end 41e. A part of the laser light L reflected at the laser light emitting end 41e goes out of the waveguide 41 from the side surfaces 41p and 41q of the flare portion 41b, but the rest is totally reflected again by the side surfaces 41g to 41j of the mode selection portion 41a. Then, it returns to the laser beam reflecting end 41f. In this way, the laser beam L reciprocates between the laser beam emitting end 41e and the laser beam reflecting end 41f and resonates.

  The planar shape of the mode selection section of the semiconductor laser device according to the present invention is not limited to the shape as in the first embodiment, but may be the shape as in this modification. Even in this case, the same effect as the first embodiment can be obtained. Further, in the mode selection unit 41a of the present modification, the side surfaces 41g and 41h and the side surfaces 41i and 41j are inclined in directions opposite to each other with respect to the direction of the predetermined axis A. By configuring the mode selection unit 41a in this way, it is possible to effectively prevent the generation of an optical path other than the laser beam L that resonates in the limited optical path, so that the spatial lateral mode can be further suppressed.

(Second modification)
Next, a second modification of the semiconductor laser element array 1 (semiconductor laser element 3) according to the first embodiment will be described. FIG. 13 is a plan view showing a waveguide 42 included in the semiconductor laser device 3b according to this modification. The difference between the semiconductor laser element 3b of the present modification and the semiconductor laser element 3 of the first embodiment is the planar shape of the mode selection unit 42a.

  The waveguide 42 according to this modification includes a mode selection unit 42a and a flare unit 42b. Among these, the planar shape of the flare part 42b is the same as the planar shape of the flare part 4b of the first embodiment described above. The mode selection unit 42a includes a pair of side surfaces 42g and 42h substantially parallel to each other, a pair of side surfaces 42i and 42j substantially parallel to each other, a pair of side surfaces 42k and 42l substantially parallel to each other, and a pair of side surfaces 42m substantially parallel to each other. And 42n. One end of the mode selector 42a is a laser beam reflecting end 42f, and the other end is connected to the flare portion 42b.

  One end of the side surface 42m of the mode selection unit 42a is in contact with one end of the laser light reflecting end 42f, and one end of the side surface 42n is in contact with the other end of the laser light reflecting end 42f. The other end of the side surface 42m is connected to one end of the side surface 42k, and the other end of the side surface 42n is connected to one end of the side surface 42l. The other end of the side surface 42k is connected to one end of the side surface 42i, and the other end of the side surface 42l is connected to one end of the side surface 42j. The other end of the side surface 42i is connected to one end of the side surface 42g, and the other end of the side surface 42j is connected to one end of the side surface 42h. The other end of the side surface 42g is connected to the side surface 42p of the flare portion 42b, and the other end of the side surface 42h is connected to the side surface 42q of the flare portion 42b.

Side 42g~42n mode selection unit 42a includes a relative angle theta ₁ with respect to the light emitting surface 1a and the light reflecting surface 1b. The side surfaces 42g and 42h, the side surfaces 42k and 42l, the side surfaces 42i and 42j, and the side surfaces 42m and 42n are inclined in different directions with respect to the direction of the predetermined axis A. Such a shape of the mode selection portion 42a is preferably realized by forming the planar shape of the ridge portion 9a of the p-type cladding layer 17 in the same manner as the planar shape of the mode selection portion 42a.

The relative angle θ ₁ between the side surfaces 42g to 42n of the mode selection unit 42a and the light emitting surface 1a and the light reflection surface 1b is determined based on the total reflection critical angle θc on the side surfaces 42g to 42n of the mode selection unit 42a. Accordingly, the pair of side surfaces 42g and 42h, 42i and 42j, 42k and 42l, and 42m and 42n of the mode selection unit 42a are arranged along the direction of the predetermined axis A from the light emitting surface 1a side or the light reflecting surface 1b side. The incident laser beam L is totally reflected. Also in this modification, the relative angles between the side surfaces 42g to 42n and the light emitting surface 1a and the light reflecting surface 1b may be different from each other.

The laser beam L reflected substantially perpendicularly along the direction of the predetermined axis A at the laser light reflecting end 42f are incident at the incident angle theta ₁ to the side surface 42m of the mode selector 42a, totally reflected. Then, the laser beam L is incident at an incident angle theta ₁ to the side surface 42n, to total reflection. Similarly, the laser beam L is a side 42l, incident 42k, 42i, 42j, 42h, and at each incident angle theta ₁ at 42 g, total reflection. Thus, the laser beam L totally reflected by the side surfaces 42g to 42n travels along the direction of the predetermined axis A, is amplified by the flare portion 42b, and reaches the laser beam emitting end 42e. A part of the laser beam L reaching the laser beam emitting end 42e is transmitted through the laser beam emitting end 42e and emitted to the outside. The other laser light L is reflected substantially vertically along the direction of the predetermined axis A at the laser light emitting end 42e. A part of the laser light L reflected at the laser light emitting end 42e goes out of the waveguide 42 from the side faces 42p and 42q of the flare part 42b, but the rest is totally reflected again by the side faces 42g to 42n of the mode selection part 42a. Then, it returns to the laser beam reflecting end 42f. In this way, the laser beam L reciprocates between the laser beam emitting end 42e and the laser beam reflecting end 42f and resonates.

  The planar shape of the mode selection section of the semiconductor laser device according to the present invention is not limited to the shape as in the first embodiment, but may be the shape as in this modification. Even in this case, the same effect as the first embodiment can be obtained. In the mode selection unit 42a of the present modification, the side surfaces 42g and 42h and the side surfaces 42i and 42j are inclined in directions opposite to each other with respect to the direction of the predetermined axis A. By configuring the mode selection unit 42a in this way, it is possible to effectively prevent the generation of an optical path other than the laser beam L that resonates in the limited optical path, so that the spatial lateral side mode can be further suppressed.

  The planar shape of the mode selection section of the semiconductor laser device according to the present invention is not limited to the shape as in the first embodiment, but may be the shape as in this modification. Even in this case, the same effect as the first embodiment can be obtained. Further, in the waveguide 42 of this modification, the side surfaces 42g and 42h, the side surfaces 42k and 42l, the side surfaces 42i and 42j, and the side surfaces 42m and 42n are opposite to each other in the inclination direction with respect to the direction of the predetermined axis A. . Thereby, the space lateral side mode can be further suppressed.

(Third Modification)
Next, a third modification of the semiconductor laser element array 1 (semiconductor laser element 3) according to the first embodiment will be described. FIG. 14 is a plan view showing a waveguide 43 included in the semiconductor laser element 3c according to this modification. The difference between the semiconductor laser device 3c of the present modification and the semiconductor laser device 3 of the first embodiment is the planar shape of the mode selection unit 43a.

  The waveguide 43 according to this modification includes a mode selection unit 43a and a flare unit 43b. Among these, the planar shape of the flare part 43b is the same as the planar shape of the flare part 4b of the first embodiment described above. The mode selection unit 43a has a pair of side surfaces 43g and 43h that are substantially parallel to each other. One end of the mode selector 43a is a laser beam reflecting end 43f, and the other end is connected to the flare portion 43b.

One end of the side surface 43g of the mode selection unit 43a is in contact with one end of the laser light reflecting end 43f, and one end of the side surface 43h is in contact with the other end of the laser light reflecting end 43f. The other end of the side surface 43g is connected to the side surface 43p of the flare portion 43b, and the other end of the side surface 43h is connected to the side surface 43q of the flare portion 43b. Side 43g and 43h have a relative angle theta ₁ with respect to the light emitting surface 1a and the light reflecting surface 1b. The relative angle theta ₁ is determined based on the total reflection critical angle θc at the side surfaces 43g and 43h. Thereby, the pair of side surfaces 43g and 43h of the mode selection unit 43a totally reflects the laser light L incident along the direction of the predetermined axis A from the light emitting surface 1a side or the light reflecting surface 1b side. The length of the waveguide 43 and the distance between the side surface 43g and the side surface 43h are such that the laser light L that resonates in the waveguide 43 between the light emitting surface 1a and the light reflecting surface 1b is a pair of side surfaces of the waveguide 43. Each of 43g and 43h is set to reflect twice.

The laser beam L reflected substantially perpendicularly along the direction of the predetermined axis A at the laser light reflecting end 43f are incident at the incident angle theta ₁ to the side surface 43h of the mode selector 43a, totally reflected. Then, the laser beam L is incident at an incident angle theta ₁ to the side surface 43 g, to total reflection. The laser beam L travels along the direction of the predetermined axis A, and re-enters at an incident angle theta ₁ to the side surface 43h, it is totally reflected. The laser light L is again incident at an incident angle theta ₁ to the side surface 43 g, to total reflection. Thus, the laser beam L totally reflected twice on each of the side surfaces 43g and 43h travels along the direction of the predetermined axis A, is amplified in the flare portion 43b, and reaches the laser beam emission end 43e. A part of the laser beam L reaching the laser beam emitting end 43e is transmitted through the laser beam emitting end 43e and emitted to the outside. The other laser light L is reflected substantially perpendicularly along the direction of the predetermined axis A at the laser light emitting end 43e. A part of the laser light L reflected at the laser light emitting end 43e goes out of the waveguide 43 from the side surfaces 43p and 43q of the flare portion 43b, but the rest is again on each of the side surfaces 43g and 43h of the mode selection portion 43a. The light is totally reflected twice and returned to the laser light reflecting end 43f. In this way, the laser beam L reciprocates between the laser beam emitting end 43e and the laser beam reflecting end 43f and resonates.

  The planar shape of the waveguide of the semiconductor laser device according to the present invention is not limited to the shape as in the first embodiment, but may be the shape as in this modification. Even in this case, the same effect as the first embodiment can be obtained. Further, in the mode selection unit 43a of the present modification, the number of reflections of the laser light L on the side surfaces 43g and 43h is larger than that of the mode selection unit 4a of the first embodiment, so that the optical path of the laser light L can be more strictly limited. it can.

(Second Embodiment)
Next, a semiconductor laser device array and a semiconductor laser device according to a second embodiment of the present invention will be described. FIG. 15 is a schematic perspective view showing the configuration of the semiconductor laser element array 1d according to the present embodiment. The semiconductor laser element array 1d is formed by integrally forming a plurality of semiconductor laser elements 3d. Similar to the semiconductor laser element array 1 of the first embodiment, the semiconductor laser element array 1d has a light emitting surface 1a and a light reflecting surface 1b. On the light emitting surface 1a, laser light emitting ends 44e of the plurality of semiconductor laser elements 3d are arranged side by side in the horizontal direction. Each of the plurality of semiconductor laser elements 3 has a convex portion 26 formed in a ridge shape. A part of the convex portion 26 on the light reflecting surface 1b side is provided such that the longitudinal direction thereof is inclined with respect to the light emitting surface 1a and the light reflecting surface 1b. Further, a part of the convex portion 26 on the light emitting surface 1a side is provided so that the width thereof increases toward the light emitting surface 1a. In the semiconductor laser element 3d, a refractive index type waveguide (described later) is formed corresponding to the convex portion 26. The laser light emitting end 44e is a resonance end face where the laser light resonates in this waveguide, and the laser light is emitted from this end face. The plurality of semiconductor laser elements 3d are arranged side by side in the direction intersecting with the longitudinal direction of the convex portion 26 and are integrally formed.

  FIG. 16 is a cross-sectional view showing a part of a VV cross section of the semiconductor laser element array 1 shown in FIG. Referring to FIG. 16, a semiconductor laser element 3d constituting the semiconductor laser element array 1d includes a substrate 11 and a stacked body 14 in which three semiconductor layers are stacked. The stacked body 14 is configured by sequentially stacking three semiconductor layers of an n-type cladding layer (second conductivity type cladding layer) 13, an active layer 15, and a p-type cladding layer (first conductivity type cladding layer) 20. Yes. The p-type cladding layer 20 is provided with a ridge portion 28a corresponding to a portion of the convex portion 26 on the light reflecting surface 1b side and a ridge portion 28b corresponding to a portion of the convex portion 26 on the light emitting surface 1a side. . A p-type cap layer 22 electrically connected to the p-type cladding layer 20 is provided on the outer layer of the ridge portions 28a and 28b. The ridge portion 28a and the p-type cap layer 22 constitute a part of the convex portion 26, and the ridge portion 28b and the p-type cap layer 22 constitute another portion of the convex portion 26.

  Furthermore, a p-side electrode layer 23 for injecting an external current is provided on the outer layer. An insulating layer 45 is provided between the p-type cladding layer 20 and the p-type cap layer 22 and the p-side electrode layer 23. The insulating layer 45 has an opening 45a. A part of the opening 45a is formed on the ridge 28a. The other part of the opening 45a is formed on the ridge portion 28b. In addition, an n-side electrode layer 29 is formed on the surface of the substrate 11 opposite to the stacked body 14.

  Since the p-side electrode layer 23 is in electrical contact only with the p-type cap layer 22 through the opening 45a, current injection from the outside corresponds to the opening 45a of the p-type cap layer 22. This is done only in the area to be performed. When current is injected into the p-type cap layer 22, the region of the active layer 15 corresponding to the opening 45a becomes the active region. In the portion corresponding to the ridge portion 28a in the active region, an effective refractive index difference is generated in the active layer 15 due to the refractive index difference between the ridge portion 28a and the peripheral portion thereof. Therefore, a refractive index type waveguide portion (mode selection portion 44a) having a shape corresponding to the planar shape of the ridge portion 28a is generated in the active layer 15. The mode selection unit 44a has an action of selecting the spatial transverse mode of the laser light, like the mode selection unit 4a of the first embodiment.

  Further, in the portion corresponding to the ridge portion 28b in the active region, an effective refractive index difference is generated in the active layer 15 due to the refractive index difference between the ridge portion 28b and its peripheral portion. Therefore, a refractive index type waveguide portion (flare portion 44b) having a shape corresponding to the planar shape of the ridge portion 28b is generated in the active layer 15. Similar to the flare portion 4b of the first embodiment, the flare portion 44b has a planar shape that is enlarged toward the light emission surface 1a (laser light emission end 44e). The mode selection unit 44 a and the flare unit 44 b constitute a waveguide 44.

  The material of each layer constituting the semiconductor laser element 3d can be the same material as that of the semiconductor laser element 3 of the first embodiment. In addition, the semiconductor laser element 3 d includes a light guide layer for confining light in the waveguide 44 between the active layer 15 and the n-type cladding layer 13 and between the active layer 15 and the p-type cladding layer 20. May be.

  Here, the p-type cladding layer 20 will be described with reference to FIGS. 17 and 18. 17 is a perspective view of the laminated body 14 including the p-type cladding layer 20, FIG. 18A is a plan view of the laminated body 14, and FIG. 18B is a cross-sectional view of the laminated body 14 shown in FIG. Sectional drawing which shows VI cross section, FIG.18 (c) is sectional drawing which shows the VII-VII cross section of the laminated body 14 shown to Fig.18 (a). As described above, the stacked body 14 is configured by sequentially stacking three semiconductor layers of the n-type cladding layer 13, the active layer 15, and the p-type cladding layer 20.

On the p-type cladding layer 20, convex ridge portions 28a and 28b are formed. Regions other than the ridge portions 28a and 28b of the p-type cladding layer 20 are thin portions 46 that are thinner than the ridge portions 28a and 28b. The ridge portion 28a has an end surface 28f and a pair of side surfaces 28g and 28h substantially parallel to each other. The pair of side surfaces 28 g and 28 h each define a region of the ridge portion 28 a and is a boundary between the ridge portion 28 a and the thin portion 46. The end surface 28f is on the light reflecting surface 1b. The side surface 28g extends from one end of the end surface 28f to the ridge portion 28b, and the side surface 28h extends from the other end of the end surface 28f to the ridge portion 28b. Side 28g and 28h, in the plan view seen from the thickness direction, are provided so as to have the relative angle theta ₁ to the light emitting surface 1a and the light reflecting surface 1b.

The ridge portion 28b has an end surface 28e and a pair of side surfaces 28p and 28q. The pair of side surfaces 28p and 28q each define a region of the ridge portion 28b and is a boundary between the ridge portion 28b and the thin portion 46. The end surface 28e is on the light emitting surface 1a. The side surface 28p extends from one end of the end surface 28e to the side surface 28g of the ridge portion 28a, and the side surface 28q extends from the other end of the end surface 28e to the side surface 28h of the ridge portion 28a. The side surfaces 28p and 28q are provided at an angle at which the lateral width increases toward the light emitting surface 1a. Specifically, side surfaces 28p and 28q, in plan view from the thickness direction, are provided so as to have the relative angle theta ₂ to the inside of the ridge portion 28b to the light emitting surface 1a.

  An opening 45a of the insulating layer 45 is provided on the ridge portions 28a and 28b. A part of the opening 45a extends along a region sandwiched between the side surfaces 28g and 28h of the ridge portion 28a. The other part of the opening 45a extends along a region sandwiched between the side surfaces 28g and 28h of the ridge portion 28b, and is provided so that its width increases toward the light emitting surface 1a.

  In the active layer 15, a waveguide 44 (mode selection unit 44a, flare unit 44b) corresponding to the planar shape of the ridges 28a and 28b is generated. Here, FIG. 19 is a plan view of the waveguide 44 generated in the active layer 15. The waveguide 44 includes a mode selection unit 44a and a flare unit 44b. In the mode selection unit 44a, a laser beam reflection end 44f is generated corresponding to the end face 28f of the ridge portion 28a. The mode selection unit 44a generates a pair of side surfaces 44g and 44h corresponding to the side surfaces 28g and 28h of the ridge portion 28a. The laser light reflecting end 44 f is a part of the cleavage surface of the active layer 15 and functions as one resonance surface for the laser light L. Further, the side surfaces 44g and 44h are surfaces generated by a difference in refractive index between the inside and outside of the mode selection unit 44a. When the refractive index continuously changes, each of the side surfaces 44g and 44h may have a certain thickness. . The side surfaces 44g and 44h function as reflective surfaces that selectively transmit or reflect the laser light L generated in the waveguide 44 according to the incident angle to the side surface.

Moreover, the flare part 44b is produced | generated on the light-projection surface 1a side with respect to the mode selection part 44a. In the flare portion 44b, a laser beam emitting end 44e is generated corresponding to the end face 28e of the ridge portion 28b. Further, a pair of side surfaces 44p and 44q are generated in the flare portion 44b corresponding to the side surfaces 28p and 28q of the ridge portion 28b, respectively. The laser beam emitting end 44 e is a part of the cleavage surface of the active layer 15 and functions as the other resonance surface for the laser beam L. Further, the side surfaces 44p and 44q are generated so that the flare portion 44b expands toward the laser beam emitting end 44e in accordance with the planar shape of the side surfaces 28p and 28q of the ridge portion 28b. In the present embodiment, side surfaces 44p and 44q and the laser beam emitting end 44e and the (light emitting surface 1a) is so as to form the same angle theta ₂ to the inside of the flared portion 44b, side surfaces 44p and 44q are generated.

Relative angle θ ₁ between the side surfaces 44g and 44h of the mode selector 44a and the light emitting surface 1a and the light reflecting surface 1b (that is, the relative angle between the side surfaces 28g and 28h of the ridge portion 28a and the light emitting surface 1a and the light reflecting surface 1b). θ ₁ ) is determined based on the total reflection critical angle θc at the side surfaces 44g and 44h of the mode selector 44a. As a result, the same operation as that of the mode selection unit 4a of the first embodiment occurs, so that the optical path of the laser light L is limited. Further, since the flare portion 44b has the same action as the flare portion 4b of the first embodiment, the laser light L propagates through the flare portion 4b while spreading in the horizontal direction under the amplification action.

Also in the present embodiment, it is preferable that the AR coating 16 and the HR coating 18 are provided on the laser light emitting end 44e and the laser light reflecting end 44f of the waveguide 44, respectively. As an example of the dimensions of the waveguide 44, the width of the mode selection unit 44a is 40 μm, the length of the mode selection unit 44a is 1200 μm, and the side surfaces 44g and 44h are relative to the light emitting surface 1a and the light reflecting surface 1b. The angle θ ₁ can be 86 °. Further, the length of the flared portion 44b and 1000 .mu.m, the relative angle theta ₂ between the side surfaces 44p and 44q and the light emitting surface 1a can be 85 ° to 87 °.

  The flare portion of the semiconductor laser device according to the present invention is not only constituted by a gain type waveguide as in the flare portion 4b of the first embodiment, but also by a refractive index type waveguide as in the flare portion 44b of this embodiment. It may be configured. As a result, similarly to the semiconductor laser device 3 of the first embodiment, the horizontal emission angle of the laser light L can be made narrower, and a laser beam with higher intensity can be emitted.

  Further, according to the semiconductor laser device 3d of the present embodiment, the width of the mode selection unit 44a is not limited as in the semiconductor laser device 3 of the first embodiment. Therefore, the difference between the width of the waveguide 44 on the laser light reflecting end 44f side and the width on the laser light emitting end 44e side (that is, the maximum width of the flare portion 44b) can be reduced, and the manufacturing process can be simplified. Furthermore, since the width of the laser beam emitting end 44e can be increased and the length of the waveguide 44 (resonator length) can be kept short, the semiconductor laser element (semiconductor laser element array) can be reduced in size. Further, this can reduce light loss inside the waveguide, so that the light emission efficiency can be improved and the threshold current can be lowered.

  Further, according to the semiconductor laser device 3d of the present embodiment, the side surfaces 44p and 44q of the flare portion 44b can be made extremely narrower than the side surfaces of the conventional flare portion, so that the spatial lateral side mode is suppressed only by the configuration of the waveguide 44. can do. Further, since the width of the laser light reflecting end 44f can be increased, the laser light density at the laser light reflecting end 44f can be reduced. As a result, COD can be suppressed even at the laser light reflecting end 44f, so that the reliability of the element can be improved and stronger laser light can be emitted.

(Third embodiment)
Next, a third embodiment of the semiconductor laser element (semiconductor laser element array) according to the present invention will be described. FIG. 20 is a cross-sectional view showing a part of the configuration of the semiconductor laser element array according to the present embodiment. The cross section shown in FIG. 20 is a cross section corresponding to the II cross section (see FIG. 1) in the semiconductor laser device array 1 of the first embodiment, and shows the cross section of the waveguide.

  The semiconductor laser element array of this embodiment includes a plurality of semiconductor laser elements 3e. The semiconductor laser element 3e includes an n-type semiconductor substrate 11, an n-type cladding layer (second conductivity type cladding layer) 31, an optical guide layer 32, an active layer 33 having a multiple quantum well structure, an optical guide layer 34, and a p-type cladding. A layer (first conductivity type cladding layer) 35 and a p-type cap layer 36 are sequentially laminated. The light guide layers 32 and 34 are layers for confining light inside the active layer 33 and in the vicinity thereof. The light guide layer 34 and the p-type cladding layer 35 constitute a convex ridge portion 39. The planar shape of the ridge portion 39 is the same as that of the ridge portion 9a of the first embodiment. A region other than the ridge portion 39 of the light guide layer 34 is a thin portion 34 a thinner than the ridge portion 39. The p-type cap layer 36 is provided on the ridge portion 39 and is electrically connected to the p-type cladding layer 35.

  The semiconductor laser element 3e further includes current blocking portions 37a and 37b, a p-side electrode layer 38, and an n-side electrode layer 29. Among these, the configuration of the n-side electrode layer 29 is the same as that of the first embodiment. The current block portions 37 a and 37 b are portions for causing current to flow through the ridge portion 39 in a concentrated manner. The current block portions 37a and 37b are made of, for example, a semiconductor having a conductivity type opposite to that of the p-type cladding layer 35 or an insulating material. The current block portions 37a and 37b are provided on the thin portion 34a along the side surfaces 39g and 39h of the ridge portion 39, respectively. The p-side electrode layer 38 is provided over the ridge portion 39 and the current blocking portions 37a and 37b, and is in contact with the p-type cap layer 36 on the ridge portion 39.

  In the active layer 33, an effective refractive index difference due to the ridge portion 39 is generated, so that a refractive index type waveguide serving as the mode selection unit 30 corresponding to the shape of the ridge portion 39 is generated. The relative angles between the side surfaces 30g and 30h of the mode selection unit 30 and the light emitting surface 1a and the light reflecting surface 1b (see FIG. 1) are determined based on the total reflection critical angle θc at the side surfaces 30g and 30h. In the present embodiment, the total reflection critical angle θc depends on the material composition of the current blocking portions 37a and 37b. That is, when the material composition of the current block portions 37a and 37b is changed, the refractive indexes of the current block portions 37a and 37b are changed. Therefore, since the effective refractive index difference between the side surfaces 30g and 30h changes, the total reflection critical angle θc changes. The side surfaces 30g and 30h of the mode selection unit 30 are surfaces generated by the difference in refractive index between the inside and outside of the mode selection unit 30, and have a certain thickness when the refractive index continuously changes. May be.

  The mode selection unit in the present invention is not limited to the ridge type configuration as in the first embodiment, but can be suitably realized in the configuration as in the semiconductor laser device 3e in this embodiment. Further, when the refractive index type waveguide is formed also in the flare portion in the present invention, the cross-sectional configuration as shown in FIG. 20 may be applied to the peripheral structure of the flare portion.

(Fourth embodiment)
Next, a fourth embodiment of the semiconductor laser element (semiconductor laser element array) according to the present invention will be described. FIG. 21 is a cross-sectional view showing a part of the configuration of the semiconductor laser element array according to the present embodiment. The semiconductor laser element array of the present embodiment is constituted by a plurality of semiconductor laser elements 3f having a so-called buried hetero structure.

  Referring to FIG. 21, the semiconductor laser device 3f of this embodiment includes a substrate 11 made of an n-type semiconductor. The semiconductor laser element 3 f includes an n-type cladding layer 71, a light guide layer 72, an active layer 73, a light guide layer 74, a p-type cladding layer 75, and a p-type cap layer 76. These layers are sequentially stacked on the substrate 11 to form a stacked body 79. The stacked body 79 has a planar shape similar to the planar shape of the ridge portion 9a of the first embodiment. The stacked body 79 has a pair of side surfaces 79g and 79h. The active layer 73 has side surfaces 73g and 73h included in the side surfaces 79g and 79h of the stacked body 79, respectively.

  Further, the semiconductor laser element 3 f includes current blocking portions 77 a and 77 b, a p-side electrode layer 78, and an n-side electrode layer 29. Among these, the configuration of the n-side electrode layer 29 is the same as that of the first embodiment. The current block portions 77 a and 77 b are portions for confining current to the active layer 73 and flowing it. The current block portions 77a and 77b are made of, for example, an undoped semiconductor material or an insulating material. The current block portion 77a is provided on the substrate 11 along the side surface 79g of the stacked body 79 (that is, along the side surface 73g of the active layer 73). The current block portion 77b is provided on the substrate 11 along the side surface 79h of the stacked body 79 (that is, along the side surface 73h of the active layer 73). The p-side electrode layer 78 is provided over the multilayer body 79, the current block portion 77 a, and the current block portion 77 b, and is in contact with the p-type cap layer 76 on the multilayer body 79.

  In the active layer 73, a refractive index difference waveguide is formed inside and outside the active layer on the side surfaces 73g and 73h, whereby a refractive index type waveguide serving as the mode selection unit 70 is formed. The mode selection unit 70 has a pair of side surfaces 70g and 70h defined by the side surfaces 73g and 73h of the active layer 73, respectively. The relative angle between the side surfaces 70g and 70h of the mode selection unit 70 and the light emitting surface 1a and the light reflecting surface 1b (that is, the relative angle between the side surfaces 73g and 73h of the active layer 73 and the light emitting surface 1a and the light reflecting surface 1b) is It is determined based on the total reflection critical angle θc at the side surfaces 70g and 70h. In the present embodiment, the total reflection critical angle θc depends on the refractive index difference between the current blocking portions 77 a and 77 b and the active layer 73. This difference in refractive index can be arbitrarily set, for example, by adjusting the material composition of the current blocking portions 77a and 77b.

  The mode selection unit in the present invention can be suitably realized even in a buried type configuration like the semiconductor laser element 3f of the present embodiment. When the refractive index type waveguide is also formed in the flare portion in the present invention, the cross-sectional configuration as shown in FIG. 21 may be applied to the peripheral structure of the flare portion.

(Fifth embodiment)
Next, a fifth embodiment of the semiconductor laser element array according to the present invention will be described. FIG. 22 is a cross-sectional view showing a part of the configuration of the semiconductor laser element array according to the present embodiment. The semiconductor laser element array of this embodiment includes a plurality of semiconductor laser elements 3g. The semiconductor laser element 3 g includes a second semiconductor unit 61. The second semiconductor unit 61 includes a substrate 51 made of an n-type semiconductor, an n-type cladding layer 52 stacked on the substrate 51, and a light guide layer 53 stacked on the n-type cladding layer 52. Has been. The second semiconductor portion 61 has a main surface 61 c on the surface of the light guide layer 53.

  The second semiconductor portion 61 has a convex ridge portion 61a. The ridge portion 61a has the same planar shape as the ridge portion 9a (see FIG. 3) of the first embodiment. The ridge portion 61a is formed at a position that divides the main surface 61c. The ridge portion 61a has a pair of side surfaces 61g and 61h serving as a boundary between the main surface 61c and the ridge portion 61a.

  The semiconductor laser element 3g includes a first semiconductor unit 60, an active layer 54 positioned between the first semiconductor unit 60 and the second semiconductor unit 61, and a p-type cap layer 57. The first semiconductor unit 60 includes a light guide layer 55 and a p-type cladding layer 56. The active layer 54, the light guide layer 55, the p-type cladding layer 56, and the p-type cap layer 57 are sequentially stacked on the second semiconductor portion 61 including the ridge portion 61a.

  The semiconductor laser element 3g includes an insulating film 58, a p-side electrode layer 59, and an n-side electrode layer 64. The p-side electrode layer 59 is provided on the p-type cap layer 57, and the insulating film 58 is provided between the p-side electrode layer 59 and the p-type cap layer 57. An opening 58a is formed in the insulating film 58 in a region corresponding to the ridge portion 61a of the second semiconductor portion 61, and the p-side electrode layer 59 and the p-type cap layer 57 are mutually connected via the opening 58a. In contact. The region of the p-type cladding layer 56 corresponding to the opening 58a of the insulating film 58 is a low resistance region 56a by diffusing Zn. The opening 58 a and the low resistance region 56 a are means for concentrating current in a region on the ridge portion 61 a in the active layer 54. The n-side electrode layer 64 is provided on the surface of the substrate 51 opposite to the main surface 61c.

  In the active layer 54, a current flows intensively in a region corresponding to the opening 58a of the insulating film 58 (that is, a region corresponding to the ridge portion 61a), whereby the mode selection unit 50 corresponding to the shape of the ridge portion 61a. A refractive index type waveguide is generated. The mode selection unit 50 has a pair of side surfaces 50g and 50h. The side surfaces 50g and 50h of the mode selection unit 50 are surfaces generated by the difference in refractive index between the light guide layer 55 and the p-type cladding layer 56 covering the active layer 54 and the active layer 54, and the planar shape thereof is the side surface of the ridge portion 61a. It is defined by 61g and 61h. When the refractive indexes of the light guide layer 55 and the p-type cladding layer 56 are continuously changed, the side surfaces 50g and 50h of the mode selection unit 50 may have a certain thickness.

  The relative angle between the side surfaces 50g and 50h of the mode selection unit 50 and the light emitting surface 1a and the light reflecting surface 1b (see FIG. 1) is determined based on the total reflection critical angle θc at the side surfaces 50g and 50h. In the present embodiment, the total reflection critical angle θc at the side surfaces 50g and 50h depends on the heights ha of the side surfaces 61g and 61h of the ridge portion 61a corresponding to the side surfaces 50g and 50h. Further, the total reflection critical angle θc at the side surfaces 50g and 50h of the mode selection unit 50 also depends on the material composition of the light guide layer 55 and the n-type cladding layer 56 on the ridge portion 61a. Therefore, the total reflection critical angle θc at the side surfaces 50g and 50h is adjusted by adjusting the height ha of the side surfaces 61g and 61h of the ridge portion 61a or the material composition of the light guide layer 55 and the n-type cladding layer 56. Can do.

  The mode selection unit in the present invention can be suitably realized even with a configuration like the semiconductor laser element 3g of the present embodiment. When the refractive index type waveguide is also formed in the flare portion in the present invention, the cross-sectional configuration as shown in FIG. 22 may be applied to the peripheral structure of the flare portion.

  FIG. 23 is a cross-sectional view showing a configuration of a semiconductor laser element 3h as a modification of the semiconductor laser element 3g. The semiconductor laser element 3h of this modification is different from the semiconductor laser element 3g of the above embodiment in the configuration of the current concentration means. The semiconductor laser element 3 h of this modification does not include the insulating film 58 of the above embodiment, and the low resistance region 56 a is not formed in the p-type cladding layer 56. In the semiconductor laser device 3h of this modification, a high resistance region 63 is formed instead of these current concentration means. The high resistance region 63 is formed on the p-type cap layer 57 side of the region of the first semiconductor portion 60 except for the ridge portion 61a. The high resistance region 63 is formed, for example, by injecting protons into the first semiconductor unit 60. In the semiconductor laser device 3h of this modification, the high-resistance region 63, which is a current concentrating means, concentrates the current in the region of the active layer 54 on the ridge portion 61a, so that the refractive index type waveguide serving as the mode selection unit 50 is obtained. It is generated in the active layer 54.

  In the semiconductor laser device 3h of this modification, like the semiconductor laser device 3g of the above embodiment, the total reflection critical angle θc of the side surfaces 50g and 50h of the mode selection unit 50 is the height of the side surfaces 61g and 61h of the ridge portion 61a. Depends on ha. Further, the total reflection critical angle θc of the side surfaces 50 g and 50 h of the mode selection unit 50 also depends on the material composition of the light guide layer 55 and the n-type cladding layer 56.

  In the present embodiment, the total reflection critical angle θc of the side surfaces 50 g and 50 h of the mode selection unit 50 also depends on the distance between the high resistance region 63 and the active layer 54. The distance between the high resistance region 63 and the active layer 54 can be adjusted, for example, by controlling the depth of proton implantation into the first semiconductor portion 60.

  The semiconductor laser device and the semiconductor laser device array according to the present invention are not limited to the above embodiments and modifications, and various other modifications are possible. For example, although the semiconductor laser device structures such as the ridge type and the buried hetero type are shown in the above embodiments, the present invention is not limited to these structures, and semiconductor laser devices and semiconductor laser devices having other various structures. Applicable to arrays. In each of the above embodiments, a GaAs-based semiconductor laser element is illustrated, but the configuration of the present invention can also be applied to a semiconductor laser element of another material system such as a GaN-based or InP-based.

1 is a schematic perspective view showing a configuration of a first embodiment of a semiconductor laser element array according to the present invention. (A) It is sectional drawing which shows a part of II cross section of the semiconductor laser element array shown in FIG. (B) It is sectional drawing which shows a part of II-II cross section of the semiconductor laser element array shown in FIG. It is a perspective view of the laminated body containing a p-type cladding layer. (A) It is a top view of a laminated body. (B) It is sectional drawing which shows the III-III cross section of the laminated body shown to Fig.4 (a). (C) It is sectional drawing which shows the IV-IV cross section of the laminated body shown to Fig.4 (a). It is a top view of the waveguide produced | generated in an active layer. It is a figure for demonstrating the light which injects into the side surface of a mode selection part with various incident angles. It is a graph for demonstrating the range in which the magnitude | size of relative angle (theta) ₁ is accept | permitted. It is a graph which shows the result of having prototyped the semiconductor laser element of 1st Embodiment, and observing the far field image. (A) It is a top view which shows an example of the shape of the waveguide of 1st Embodiment. (B) It is a top view which shows an example of the waveguide shape of the conventional flare type | mold semiconductor laser element for a comparison. (A)-(d) The enlarged plan view of the semiconductor laser element array in each manufacturing process is shown. (A)-(d) The expanded sectional view of the semiconductor laser element array in each manufacturing process is shown. It is a top view which shows the waveguide which the semiconductor laser element by a 1st modification has. It is a top view which shows the waveguide which the semiconductor laser element by a 2nd modification has. It is a top view which shows the waveguide which the semiconductor laser element by a 3rd modification has. It is a schematic perspective view which shows the structure of the semiconductor laser element array by 2nd Embodiment. It is sectional drawing which shows a part of VV cross section of the semiconductor laser element array shown in FIG. It is a perspective view of the laminated body containing a p-type cladding layer. (A) It is a top view of a laminated body. (B) It is sectional drawing which shows the VI-VI cross section of the laminated body shown to Fig.18 (a). (C) It is sectional drawing which shows the VII-VII cross section of the laminated body shown to Fig.18 (a). It is a top view of the waveguide produced | generated in an active layer. It is sectional drawing which shows a part of structure of the semiconductor laser element array by 3rd Embodiment. It is sectional drawing which shows a part of structure of the semiconductor laser element array by 4th Embodiment. It is sectional drawing which shows a part of structure of the semiconductor laser element array by 5th Embodiment. It is sectional drawing which shows the structure of the modification of the semiconductor laser element by 5th Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1a ... Light emission surface, 1b ... Light reflection surface, 1 ... Semiconductor laser element array, 3, 3a-3g ... Semiconductor laser element, 4 ... Waveguide, 4a ... Mode selection part, 4b ... Flare part, 4e ... Laser beam emission End 4f Laser reflecting edge 4g 4h 4p 4q Side surface 9a Ridge portion 9b Hill-shaped portion 9g 9h 9u Side surface 10 Thin portion 11 Substrate 12 Stack 13 ... n-type cladding layer, 15 ... active layer, 17 ... p-type cladding layer, 19 ... p-type cap layer, 21 ... insulating layer, 21a ... opening, 23 ... p-side electrode layer, 25a, 25b ... convex Part, 29 ... n-side electrode layer.

Claims (6)

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 light emitting surface and a light reflecting surface provided side by side in a predetermined axial direction and facing each other;
A waveguide formed in the active layer and reaching the light reflecting surface and the light emitting surface;
The waveguide has a mode selection part and a flare part located on the light emission surface side with respect to the mode selection part,
The relative angle θ between the side surface in the mode selection unit and the light emitting surface and the light reflecting surface is based on the total reflection critical angle θc on the side surface,
The semiconductor laser device, wherein a width of the flare portion in a direction intersecting the predetermined axial direction is increased toward the light emitting surface.   2. The semiconductor laser device according to claim 1, wherein the pair of side surfaces of the flare portion are substantially equiangular on the inner side of the waveguide with respect to the light emitting surface.   The length of the mode selection unit and the mode so that the light resonating in the waveguide between the light exit surface and the light reflection surface is reflected the same number of times on each of the pair of side surfaces of the mode selection unit. The semiconductor laser device according to claim 1, wherein an interval between the pair of side surfaces of the selection unit is set.   The relative angle θ between the side surface of the mode selection unit, the light emitting surface, and the light reflecting surface is in a range of θc ≦ θ ≦ θc + 1 °. The semiconductor laser device according to item.   The relative angle θ between the side surface of the mode selection unit, the light exit surface, and the light reflection surface is substantially equal to the total reflection critical angle θc on the side surface of the mode selection unit. The semiconductor laser device according to any one of Items 1 to 3. A plurality of semiconductor laser elements according to any one of claims 1 to 5,
The semiconductor laser element array, wherein the plurality of semiconductor laser elements are arranged in a row in a direction intersecting with the predetermined axial direction.

Images