JP2012142504A - Semiconductor light-emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor light-emitting element capable of changing the shape of light intensity distribution of a far-field pattern in the horizontal direction to a single-peak shape.SOLUTION: A semiconductor light-emitting element 100 having a light-emitting layer comprises: a first optical waveguide 121 having a first light emission surface 131a emitting first light from the light-emitting layer and a rear-end surface 100b reflecting light from the light-emitting layer as both ends; and a second optical waveguide 122 having a second light emission surface 141a emitting second light from the light-emitting layer and the rear-end surface 100b as both ends. The first optical waveguide 121 and the second optical waveguide 122 are connected to the rear-end surface, and the first light emission surface 131a and the second light emission surface 141a are non-parallel to each other so as to bring the optical axis of the first light and the optical axis of the second light closer to each other.

Description

  The present invention relates to a semiconductor light emitting device, and more particularly to a superluminescent diode with light emission in a visible light region from blue purple to red.

  2. Description of the Related Art In recent years, semiconductor light emitting devices such as semiconductor lasers (LDs) and super luminescent diodes (SLDs) have attracted attention as mercury-free high-intensity light sources for displays such as projectors.

  Among them, semiconductor lasers have the features of high brightness and excellent directivity of emitted light, but the laser light that is emitted light is coherent light (coherent light), so light that is diffusely reflected on the screen surface. Speckle noise caused by interference is a problem. On the other hand, as a light source without such speckle noise, there is an LED (Light Emitting Diode) whose outgoing light is non-coherent light (incoherent light). However, when an LED is used as a light source such as a projector, the directivity of emitted light is low, so that the coupling efficiency in the optical system constituting the display is low, and as a result, the luminance of the display is lowered.

  For such a problem, there is a semiconductor light emitting element such as an SLD as a light source having both directivity and low coherency. The SLD is a semiconductor light emitting device using an optical waveguide as in the LD, but suppresses laser oscillation by greatly reducing the reflectance of the emission end face, and realizes both low coherent light and high directivity. Further, when a semiconductor light emitting element is used as a light source for a display, it is necessary to increase the output of the semiconductor light emitting element as a light source in order to increase the brightness of the screen.

  A structure of such a semiconductor light emitting device that realizes high output with low coherence is proposed in Patent Document 1, for example. Hereinafter, the structure of a conventional semiconductor light emitting device will be described with reference to FIG.

  As shown in FIG. 15, a conventional semiconductor light emitting device 900 has a first optical waveguide 921 and a second optical waveguide 922 connected to a front end surface 900a and a rear end surface 900b. The first optical waveguide 921 and the second optical waveguide 922 are connected to each other at the rear end surface 900b, and are configured such that the distance between them increases from the rear end surface 900b toward the front end surface 900a.

  In addition, a reflective film 950 is formed on the rear end surface 900b, and the light guided through the first optical waveguide 921 and the second optical waveguide 922 is reflected by the reflective film 950. On the other hand, the front end surface 900a is a light emitting surface of the first optical waveguide 921 and a light emitting surface of the second optical waveguide 922. From the front end surface 900a which is the light emitting surface, the first optical waveguide 921 is formed. In addition, the light is amplified in the second optical waveguide 922 to emit light having high output and low coherence.

JP 2009-238843 A

  However, the configuration of the conventional semiconductor light emitting device 900 has the following problems.

  In the conventional semiconductor light emitting device 900, since the first optical waveguide 921 and the second optical waveguide 922 are connected to the front end surface 900a in a direction extending from each other, the emission direction of the emitted light emitted from the respective optical waveguides Are different from each other, and the respective emitted lights are emitted in the directions in which they spread. Further, since there is a refractive index difference between the effective refractive index of the optical waveguide and the refractive index on the exit side (external) of the optical waveguide, the above-described spread in the exit direction is expanded. As a result, there is a problem that two light intensity peaks occur in the light intensity distribution in the horizontal direction of the far field image (FFP: Far Field Pattern) of the emitted light.

  Further, if the reflectance of the light emitting end face (front end face) varies in the plane, a difference occurs in the reflectance between the light emitting surface of the first optical waveguide and the light emitting surface of the second optical waveguide. A difference occurs in the light intensity peak. As a result, for example, when semiconductor light-emitting elements are mass-produced, there is a problem that the FFP light intensity distribution shape in each semiconductor light-emitting element varies greatly.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a semiconductor light emitting device capable of unimodal light intensity distribution shape in the horizontal direction of a far-field image.

  In order to solve the above-described problem, an aspect of the first semiconductor light emitting device according to the present invention is a semiconductor light emitting device having a light emitting layer, wherein the first light is emitted from the light emitting layer. A first optical waveguide having both ends of an exit surface and a rear end surface that reflects light from the light emitting layer, and a second light exit surface that emits second light from the light emitting layer and the rear end surface are both ends. And the first optical waveguide and the second optical waveguide are connected to each other at the rear end surface, and the first light output surface and the second light output surface are connected to each other. Is configured to be non-parallel to each other so that the optical axis of the first light and the optical axis of the second light are close to each other.

  With this configuration, the angle between the first light emitted from the first light emitting surface and the second light emitted from the second light end surface can be controlled to be small, so that the semiconductor light emitting device The light distribution in the horizontal direction of the far-field image of the emitted light as a whole can be unimodal.

の関係を満たすことが好ましい。 Further, in one aspect of the first semiconductor light emitting device according to the present invention, an acute angle formed by the perpendicular of the first light emitting surface and the first optical waveguide is φ1, and the perpendicular of the second light emitting surface is And the second light guide surface is φ2, the angle between the first light exit surface and the second light exit surface is γ, and the first light guide and the second light guide the effective refractive index of the waveguide and n _i, the refractive index at the outside of the semiconductor light emitting device and n _a, full width at half maximum of the far-field pattern in the horizontal direction in the first light emitted from the first light emitting surface Is ω1, and the full width at half maximum of the horizontal far-field image in the second light emitted from the second light exit surface is ω2,

It is preferable to satisfy the relationship.

  With this configuration, the acute angle between the first light exiting from the first light exit surface and the second light exiting from the second light end surface spreads in the horizontal direction due to diffraction of the light exiting from each end surface. It becomes smaller than the angle. Thereby, the far-field image in the horizontal direction can be unimodal.

  Furthermore, in one aspect of the first semiconductor light emitting device according to the present invention, a connection portion between the first optical waveguide and the second optical waveguide on the rear end surface is axisymmetric with respect to a normal to the rear end surface. It is preferable that

  With this configuration, light that reaches the rear end face of the light generated in the first optical waveguide is reflected by the rear end face and enters the second optical waveguide, and receives and amplifies the optical gain in the second optical waveguide. After that, the light is emitted from the second light exit surface. Further, the light generated in the second optical waveguide that has reached the rear end face is reflected by the rear end face and enters the first optical waveguide, and is amplified by receiving the optical gain in the first optical waveguide. Later, it is emitted from the first light exit surface. Thereby, the amplification length of light can be made twice the resonator length.

  Furthermore, in one aspect of the first semiconductor light emitting device according to the present invention, it is preferable that the first optical waveguide and the second optical waveguide are each formed in a linear shape.

  With this configuration, it is possible to eliminate a radiation loss caused by the light traveling in the optical waveguide being bent from the traveling direction.

  Furthermore, in one aspect of the first semiconductor light emitting device according to the present invention, at least one of the first optical waveguide and the second optical waveguide has a curved portion, and the first optical waveguide and the first optical waveguide It is preferable not to intersect the second optical waveguide.

  With this configuration, there is no branch point in the optical waveguide, so that it is possible to eliminate light loss that occurs at the branch point of the optical waveguide.

  Furthermore, in one aspect of the first semiconductor light emitting device according to the present invention, it is preferable that at least one of the first light emitting surface and the second light emitting surface is a cleaved surface.

  Thereby, a light emission surface can be formed by cleavage.

  Furthermore, in one aspect of the first semiconductor light emitting device according to the present invention, it is preferable that at least one of the first light emitting surface and the second light emitting surface is formed by a groove.

  Thereby, the light emission surface which inclines with respect to a front-end surface can be formed easily.

の関係を満たすものである。 One embodiment of the second semiconductor light emitting device according to the present invention is a semiconductor light emitting device having a light emitting layer, the first light emitting surface for emitting the first light from the light emitting layer, and the light emitting layer. A first optical waveguide having both ends of a rear end face reflecting light from the light source, a second light emitting surface for emitting second light from the light emitting layer, and a second optical waveguide having both ends of the rear end face The first optical waveguide and the second optical waveguide are connected at the rear end surface, and the first light emitting surface and the second light emitting surface are parallel to each other, The acute angle formed by the perpendicular of the first light exit surface and the first optical waveguide is φ1, the acute angle formed by the perpendicular of the second light exit surface and the second optical waveguide is φ2, and the first the effective refractive index of the first optical waveguide and said second optical waveguide and n _i, bending at the outside of the semiconductor light emitting element Rates and n _a, a full width at half maximum of the horizontal far-field pattern in the first light emitted from the first light emitting surface and .omega.1, the second light emitted from the second light emitting surface If the full width at half maximum of the horizontal far-field image at ω2 is ω2,

It satisfies the relationship.

  With this configuration, the acute angle formed by the first light exiting from the first light exit surface and the second light exiting from the second light end surface is the horizontal spread angle due to diffraction of the light exiting from each end surface. Smaller than. Thereby, the far-field image in the horizontal direction can be unimodal.

  Furthermore, in one aspect of the second semiconductor light emitting device according to the present invention, a connection portion between the first optical waveguide and the second optical waveguide on the rear end surface is axisymmetric with respect to a normal to the rear end surface. It is preferable that

  With this configuration, light that reaches the rear end face of the light generated in the first optical waveguide is reflected by the rear end face and enters the second optical waveguide, and receives and amplifies the optical gain in the second optical waveguide. After that, the light is emitted from the second light exit surface. Further, the light generated in the second optical waveguide that has reached the rear end face is reflected by the rear end face and enters the first optical waveguide, and is amplified by receiving the optical gain in the first optical waveguide. Later, it is emitted from the first light exit surface. Thereby, the amplification length of light can be made twice the resonator length.

  Furthermore, in one aspect of the second semiconductor light emitting device according to the present invention, it is preferable that at least one of the first optical waveguide and the second optical waveguide has a curved portion.

  With this configuration, the chip width can be reduced.

  Furthermore, in one aspect of the second semiconductor light emitting device according to the present invention, it is preferable that the first optical waveguide and the second optical waveguide are axisymmetric with respect to a normal to the rear end surface.

  Thereby, a laser beam can be generated with high efficiency.

  Furthermore, in one aspect of the second semiconductor light emitting device according to the present invention, it is preferable that at least one of the first optical waveguide and the second optical waveguide has a bent portion.

  Thereby, the optical axis of the first light emitted from the first light emitting surface and the optical axis of the second light emitted from the second light emitting surface can be easily brought close to each other.

  Furthermore, in one aspect of the second semiconductor light emitting device according to the present invention, the bent portion is preferably connected to a light reflecting surface that reflects light.

  With this configuration, among the photons generated in the optical waveguide, those that reach the bent portion are reflected by the light reflecting surface and returned to the waveguide again, and can be amplified by receiving the optical gain.

  Furthermore, in one aspect of the second semiconductor light emitting element according to the present invention, the light reflecting surface is preferably formed by a groove formed in the vicinity of the bent portion.

  Thereby, a light reflection surface can be easily formed.

Furthermore, in one aspect of the second semiconductor light emitting device according to the present invention, the optical waveguide having the bent portion includes a first straight portion on the light emitting side and a second straight line on the rear end face side with the bent portion as a boundary. and a section, perpendicular to the second straight portion and the acute angle of the light reflection surface is preferably larger than _{arcsin (n a / n i)} .

  With this configuration, the light reflection surface can be made a total reflection surface, so that the reflectance can be as close to 100% as possible. For this reason, a process for manufacturing a semiconductor layer having a high reflectance with respect to the light reflecting surface is not required, and the manufacturing cost for forming the end surface can be reduced.

  Furthermore, in one aspect of the second semiconductor light emitting device according to the present invention, it is preferable that at least one of the first light emitting surface and the second light emitting surface is a cleaved surface.

  Thereby, a light emission surface can be formed by cleavage.

  Furthermore, in one aspect of the second semiconductor light emitting device according to the present invention, it is preferable that at least one of the first light emitting surface and the second light emitting surface is formed by a groove.

  Thereby, the light emission surface which inclines with respect to a front-end surface can be formed easily.

  According to the semiconductor light emitting device of the present invention, the horizontal far-field image of the emitted light of the semiconductor light emitting device can be unimodal.

1A is a top view of the semiconductor light emitting device according to the first embodiment of the present invention, FIG. 1B is a perspective view of the semiconductor light emitting device, and FIG. It is sectional drawing of the same semiconductor light-emitting device in the AA 'line of Fig.1 (a). FIG. 2A is a top view at the time of operation of the semiconductor light emitting device according to the first embodiment of the present invention, and FIG. 2B is a unimodal light intensity distribution in the horizontal direction of the far-field image. FIG. 2C is a diagram illustrating a state in which the light intensity distribution in the horizontal direction of the far-field image is non-unimodal. FIG. 3A to FIG. 3F show a method for manufacturing a semiconductor light emitting device according to the first embodiment of the present invention. FIG. 3A shows a step of forming a laminated structure on a substrate. FIG. 3B is a diagram for explaining the optical waveguide forming step, and FIG. 3C is a diagram for explaining the groove forming step. (D) is a figure for demonstrating a primary separation (primary cleavage) process, FIG.3 (e) is a figure for demonstrating a high reflectance layer formation process, FIG.3 (f) is FIG. It is a figure for demonstrating a secondary separation (secondary cleavage) process. 4A is a diagram for explaining parameters necessary for designing the semiconductor light emitting device according to Example 1 of the first embodiment of the present invention, and FIG. 4B is a diagram illustrating the semiconductor light emitting device. It is a figure for demonstrating the suitable range of the parameter in. 5A is a diagram showing evaluation characteristics of a horizontal far-field image in an example of the semiconductor light emitting device according to the first embodiment of the present invention, and FIG. FIG. 5C is a diagram showing evaluation characteristics of a horizontal far-field image in a semiconductor light-emitting element according to Comparative Example 2, and FIG. FIG. 5D is a diagram showing evaluation characteristics of a horizontal far-field image in the semiconductor light emitting element according to Comparative Example 3. FIG. 6 is a top view of a semiconductor light emitting device according to the second embodiment of the present invention. FIG. 7 is a view for explaining a preferable range of parameters in the semiconductor light emitting device according to the second embodiment of the present invention. FIG. 8 is a graph showing the results of theoretical calculation of the dependence of the reflectivity on the optical waveguide and the tilt angle of the tilted end surface when the guided light is reflected by the tilted end surface in the semiconductor light emitting device according to the present invention. It is. FIG. 9 is a top view of a semiconductor light emitting device according to Modification 1 of the second embodiment of the present invention. FIG. 10 is a top view of a semiconductor light emitting element according to Modification 2 of the second embodiment of the present invention. FIG. 11 is a top view of a semiconductor light emitting device according to the third embodiment of the present invention. 12A to 12E show a method for manufacturing a semiconductor light emitting device according to the third embodiment of the present invention, and FIG. 12A is a diagram for explaining an optical waveguide forming step. 12B is a diagram for explaining the groove forming step, and FIG. 12C is a diagram for explaining the primary separation (primary cleavage) step, and FIG. 12D. These are the figures for demonstrating a high reflectance layer formation process, and FIG.12 (e) is a figure for demonstrating a secondary separation (secondary cleavage) process. FIG. 13 is a top view of a semiconductor light emitting device according to a modification of the third embodiment of the present invention. FIG. 14 is a top view of a semiconductor light emitting device according to the fourth embodiment of the present invention. FIG. 15 is a diagram for explaining the structure of a conventional semiconductor light emitting device.

  Hereinafter, semiconductor light emitting devices according to embodiments of the present invention will be described with reference to the drawings. In addition, each embodiment shown below is an example, Comprising: This invention is not limited to these embodiment. In the following embodiments, the description of the same or similar components is omitted or simplified unless particularly necessary.

(First embodiment)
First, a semiconductor light emitting device 100 according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1A is a top view of the semiconductor light emitting device 100 according to the first embodiment of the present invention, FIG. 1B is a perspective view of the semiconductor light emitting device 100, and FIG. These are sectional drawings of the semiconductor light emitting element 100 in the AA 'line of Fig.1 (a).

  As shown in FIGS. 1A and 1B, the semiconductor light emitting device 100 according to the first embodiment of the present invention includes a front end surface 100a that is a cleaved end surface on the side from which light from the light emitting layer is extracted, An SLD having a rear end surface 100b which is a cleaved end surface opposite to the front end surface 100a, and has two optical waveguides, for example, a first optical waveguide 121 and a second optical waveguide 122 which are configured by ridge stripes. . The rear end surface 100b is configured to reflect light from the light emitting layer, and a high reflectivity layer 150 made of, for example, a dielectric multilayer film and having a reflectivity of 90% or more is formed on the rear end surface 100b. ing.

  The first optical waveguide 121 is an entirely linear optical waveguide having both the first light emitting surface 131a and the rear end surface 100b for emitting the first light from the light emitting layer as both ends. The optical waveguide 122 is a linear optical waveguide as a whole having both ends of the second light emitting surface 141a that emits the second light from the light emitting layer and the rear end surface 100b.

  The first optical waveguide 121 and the second optical waveguide 122 are connected at one place, and the connecting portion is also in contact with the rear end face 100b. That is, in the present embodiment, one end portion on the rear end face side of the first optical waveguide 121 and one end portion on the rear end face side of the second optical waveguide 122 are connected on the rear end face 100b. Further, the other end portion on the front end face side of the first optical waveguide 121 and the other end portion on the front end face side of the second optical waveguide 122 are not connected, and the first optical waveguide 121 and the second light guide are not connected. The waveguide 122 is connected to a first light exit surface 131a and a second light exit surface 141a that are formed non-parallel to the front end surface 100a, respectively. The first optical waveguide 121 and the second optical waveguide 122 are formed so that the distance between the first optical waveguide 121 and the second optical waveguide 122 increases from the rear end surface 100b where the connecting portion is formed toward the front end surface 100a.

  Further, in the semiconductor light emitting device 100 according to the present embodiment, the first groove 131 is formed so as to cut out the first optical waveguide 121 in the vicinity of the front end surface 100a. An emission surface 131a is formed. Similarly, a second groove 141 is formed so as to cut out the second optical waveguide 122 in the vicinity of the front end surface 100a, thereby forming a second light emitting surface 141a. The first groove 131 and the second groove 141 are formed such that the first light exit surface 131a and the second light exit surface 141a are inclined with respect to the front end surface 100a. Furthermore, in the present embodiment, the third groove portion 132 and the fourth groove portion 142 are formed so as to cut out the vicinity of the rear end surface 100b. In addition, the high reflectance layer 150 is laminated | stacked on the 3rd groove part 132 and the 4th groove part 142 in the direction which goes to the front end surface 100a from the rear end surface 100b.

  Thus, in the semiconductor light emitting device 100 according to the present embodiment, the first light emitting surface 131a and the second light emitting surface 141a are the main axes of the first light emitted from the first light emitting surface 131a ( The optical axis is inclined with respect to the front end face 100a so that the main axis (optical axis) of the second light emitted from the second light exit surface 141a approaches and becomes parallel to each other, and is formed non-parallel to each other. .

  As will be described later, the first groove 131 on the front end face side and the third groove 132 on the rear end face side are formed when one recess is formed in an adjacent portion of adjacent elements before element separation. Formed simultaneously. Similarly, the second groove portion 141 and the fourth groove portion 142 are formed at the same time when one concave portion is formed in the adjacent portion of the adjacent element before element isolation.

  Further, when the first optical waveguide 121 and the second optical waveguide 122 are formed to separate the elements, the optical waveguide of the adjacent element remains in the element, and the optical waveguide remaining portion 123 is formed on the surface near the front end surface 100a. It is formed.

  Since the third groove portion 132, the fourth groove portion 142, and the optical waveguide remaining portion 123 are not the functional configuration of the semiconductor light emitting device 100, the first optical waveguide 121, the second optical waveguide 121, which are the functional configuration of the semiconductor light emitting device 100, and the second optical waveguide portion. The optical waveguide 122, the first groove 131, and the second groove 141 are designed so as to be arranged at a location different from these functional configurations.

  Next, the structure in the stacking direction of the semiconductor light emitting device 100 according to the first embodiment of the present invention will be described with reference to FIG.

  As shown in FIG. 1C, the semiconductor light emitting device 100 according to this embodiment includes a buffer layer (not shown) made of GaN doped with Si, for example, on a substrate 101 such as GaN or sapphire, An n-type cladding layer 102 made of an AlGaN layer doped with Si, for example, an n-type guide layer 103 made of a GaN layer doped with Si, for example, an active layer in which three GaN quantum barrier layers and InGaN quantum well layers are alternately stacked (Light-emitting layer) 104, for example, a p-type guide layer 105 made of Mg-doped GaN, for example, a carrier overflow suppression layer (OFS layer) 106 made of Mg-doped AlGaN layer, for example, an Mg-doped AlGaN layer And a p-type GaN contact layer doped with, for example, Mg (see FIG. Without) is formed are sequentially laminated.

On the upper portion of the p-type cladding layer 107, a first optical waveguide 121 and a second optical waveguide 122 are formed which are formed of a ridge portion processed into a ridge stripe shape. On the p-type cladding layer 107, a block layer 110 made of, for example, a SiO ₂ dielectric is formed so as to cover the flat portion and the side surface of the ridge stripe. A p-side electrode 108 is formed on the top surface of the ridge portion of the p-type cladding layer 107. A wiring electrode 109 connected to the p-side electrode 108 is formed on the p-side electrode 108 and the block layer 110. An n-side electrode 111 is formed on the surface (back surface) opposite to the n-type cladding layer 102 of the substrate 101.

  The first groove 131, the second groove 141, the third groove 132, and the fourth groove 142 shown in FIGS. 1A and 1B have a depth of the n-type cladding layer 102. It is preferable to configure so as to reach the vicinity of the boundary with the substrate 101 in FIG. Thereby, the first groove 131 and the second groove 141 when forming the first light emission surface 131a and the second light emission surface 141a are prevented from changing (deteriorating) the effect of confining light. be able to.

  Next, the operation of the semiconductor light emitting device 100 according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 2A is a top view at the time of operation of the semiconductor light emitting device 100 according to the first embodiment of the present invention, and FIGS. 2B and 2C are far-field images of the semiconductor light emitting device. It is a figure showing light intensity distribution in the horizontal direction.

  Returning to FIG. 1C, in the semiconductor light emitting device 100, electrons and holes injected from the n-side electrode 111 and the p-side electrode 108 recombine in the active layer 104, thereby generating spontaneous emission light. A part of the spontaneous emission light generated is amplified by receiving a high gain by stimulated emission while being guided through the first optical waveguide 121 and the second optical waveguide 122 shown in FIG. Are emitted from the light emitting surface 131a and the second light emitting surface 141a to the outside.

  That is, as shown in FIG. 2A, the light that has reached the rear end surface 100 b out of the spontaneous emission light that travels through the first optical waveguide 121 is reflected by the rear end surface 100 b to the second optical waveguide 122. move on. On the other hand, the light that has reached the rear end surface 100 b among the spontaneous emission light traveling through the second optical waveguide 122 is reflected by the rear end surface 100 b and proceeds to the first optical waveguide 121. As described above, the spontaneous emission light generated inside the device is amplified by receiving a high gain by stimulated emission while traveling through the first optical waveguide 121 and the second optical waveguide 122, and the first light emission surface 131a. The first emission light 121L is emitted from the second light emission surface, and the second emission light 122L is emitted from the second light emission surface 141a.

  Here, as shown in FIG. 2A, the angle between the main axis (optical axis) X1 of the first outgoing light 121L and the central axis X0 of the semiconductor light emitting element 100 is Δθ1, and the second outgoing light 122L When the angle formed between the main axis X2 (optical axis) and the central axis X0 (optical axis) of the semiconductor light emitting device 100 is Δθ2, the deviation between the main axis X1 of the first outgoing light 121L and the main axis X2 of the second outgoing light 122L. The angle Δθ is represented by Δθ = | Δθ1 + Δθ2 | or Δθ = | Δθ1-Δθ2 |. Also, as shown in the figure, the full width at half maximum of the horizontal far-field image in the first outgoing light 121L and the second outgoing light 122L is ω1 and ω2, respectively.

  At this time, by making the deviation angle Δθ smaller than the full width at half maximum ω1 of the first outgoing light 121L and the full width at half maximum ω2 of the second outgoing light 122L, the first outgoing light 121L and the second outgoing light are obtained. As shown in FIG. 2B, the light intensity distribution in the horizontal direction of the far-field pattern of the emitted light 100L of the semiconductor light emitting element 100, which is the combined light with 122L, is unimodal.

  On the other hand, when the deviation angle Δθ is larger than the full width at half maximum ω1 of the first emitted light 121L and the full width at half maximum ω2 of the second emitted light 122L, the far-field image of the emitted light from the semiconductor light emitting element is obtained. The light intensity distribution in the horizontal direction has a shape (non-unimodal) having two intensity peaks as shown in FIG.

  In the semiconductor light emitting device 100 according to the present embodiment, as described above, the first light emitting surface 131a and the second light emitting surface 141a are formed non-parallel as described above, so FIG. As shown in FIG. 5, the light intensity distribution of the horizontal far-field image in the emitted light 100L of the semiconductor light emitting device 100 is unimodal.

  Next, a method for manufacturing the semiconductor light emitting device 100 according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 3A to FIG. 3F are diagrams for explaining each step in the method for manufacturing the semiconductor light emitting device according to the first embodiment of the present invention. FIG. 3 shows a part of the wafer, and a case where a total of nine semiconductor light emitting elements 100 in three rows in the vertical direction and three rows in the horizontal direction are formed on the wafer will be described. In FIG. 3, the broken line represents the chip region of one semiconductor light emitting element 100.

  First, as shown in FIG. 3A, for example, by using a metal organic chemical vapor deposition (MOCVD) method on a C-plane of a substrate 101 made of n-type hexagonal GaN, FIG. A laminated structure made of a nitride semiconductor of Al (aluminum), Ga (gallium) and In (indium) is formed as shown in c).

Specifically, as shown in FIG. 1C, first, an n-type cladding layer 102 made of n-type Al _0.03 Ga _0.97 N doped with Si is grown on a substrate 101. Subsequently, an n-type guide layer 103 made of n-type GaN doped with Si, a barrier layer made of GaN, and a quantum well layer of In _0.15 Ga _0.85 N are alternately formed on the n-type cladding layer 102. Then, the active layer 104 having three layers is grown. Subsequently, a p-type guide layer 105 made of p-type GaN doped with Mg is grown on the active layer 104, and carriers made of Al _0.20 Ga _0.80 N are grown on the p-type guide layer 105. An overflow suppression layer (OFS layer) 106 is grown. Subsequently, on the OFS layer 106, a p-type cladding layer 107, which is a strained superlattice layer of a p-type Al _0.10 Ga _0.90 N layer doped with Mg and a GaN layer, and Mg were doped. A p-type contact layer (not shown) made of p-type GaN is sequentially grown.

  The structure of the semiconductor light emitting device according to this embodiment is an example, and the structure and growth method of the semiconductor light emitting device are not limited to this. For example, a method such as a molecular beam epitaxy (MBE) method or a chemical beam epitaxy (CBE) method may be used as a crystal growth method when forming a semiconductor light emitting element. The substrate 101 can also be a substrate such as a sapphire substrate or a silicon substrate, in addition to n-type hexagonal GaN having a C-plane surface. Furthermore, a GaN substrate having an m-plane or semipolar surface or a sapphire substrate having an r-plane surface as the substrate 101, and a laminated structure of a nitride semiconductor in which the laminated surface is a nonpolar or semipolar surface May be used.

  Next, as shown in FIG. 3B, the first optical waveguide 121 and the second optical waveguide 122 are formed on the nitride semiconductor multilayer structure formed on the substrate 101. At this time, as shown in FIG. 3B, the first optical waveguide 121 and the second optical waveguide are prevented so that the optical waveguide does not reach the cleavage plane at the time of primary separation (primary cleavage) of the element. 122 is formed by extending both end portions thereof to element regions adjacent to each other in the vertical direction. As a result, even if the cleavage plane is displaced at the time of cleavage, cleavage end faces can be formed in the first optical waveguide 121 and the second optical waveguide 122.

Specifically, first, a mask material such as a SiO ₂ film is deposited, then a first mask film having a predetermined shape is formed by patterning, and the p-type cladding layer 107 and the p-type contact layer are processed by dry etching. Thus, two ridge-shaped optical waveguides are formed. Next, the first mask film is removed, and a mask material of SiO ₂ film is again deposited on the entire surface of the wafer. Subsequently, the SiO ₂ film is patterned by a lithography method and a wet etching method using a buffered hydrofluoric acid solution to form a second mask film on the top surfaces of the first optical waveguide 121 and the second optical waveguide 122, That is, a second mask film having an opening that exposes the p-type cladding layer 107 other than the ridge is formed, and the block layer 110 made of a dielectric is formed. Subsequently, the p-side electrode 108 made of, for example, palladium (Pd) / platinum (Pt) is formed in each opening of the block layer 110 by electron beam evaporation. Thereafter, a heat treatment at a temperature of 400 ° C. is applied to obtain a good contact resistance. Next, titanium (Ti) / platinum (Pt) / gold is electrically connected to the p-side electrode 108 on the block layer 110 including the p-side electrode 108 by lithography and electron beam evaporation. A wiring electrode 109 made of (Au) is formed.

  Next, as shown in FIG. 3C, the first groove 131 and the second groove 141 are formed in order to form the first light emitting surface 131a and the second light emitting surface 141a.

Specifically, first, after removing the SiO ₂ film used for the mask with a buffered hydrofluoric acid solution (BHF), a mask that is, for example, a SiO ₂ film is deposited again and patterned by photolithography and dry etching. By performing dry etching, one end of the first optical waveguide 121 is cut away to form a recess 130 composed of the first groove 131 and the third groove 132, and the second optical waveguide is formed. A concave portion 140 composed of the second groove portion 141 and the fourth groove portion 142 is formed so as to cut out one end portion of 122. At this time, the recesses 130 and 140 are formed so as to cut out the optical waveguide extending to the adjacent element region. That is, the third groove portion 132 and the fourth groove portion 142 are formed to cut out the optical waveguide extending to the adjacent element regions.

Subsequently, on the surface of the first light exit surface 131a formed by the formation of the first groove 131, and the surface of the second light exit surface 141a formed by the formation of the second groove 141, As the protective film, a laminated film (not shown) such as SiO ₂ or Al ₂ O _{3 is formed} .

  Next, as shown in FIG. 3D, primary separation is performed in which the semiconductor light-emitting elements are divided from the wafer into a bar state that is connected in a horizontal row. Thereby, the front end surface 100a and the rear end surface 100b of the semiconductor light emitting element 100 are formed.

  Specifically, first, the back surface of the substrate 101 is ground and polished to reduce the thickness of the substrate 101 to a predetermined thickness. Thereafter, an n-side electrode 111 made of, for example, Ti / Pt / Au is formed on the back surface of the thinned substrate 101. Here, the film thicknesses of Ti, Pt, and Au are 10 nm, 50 nm, and 100 nm, respectively. At this time, it is desirable to form an electrode pattern by performing etching only on the upper Au film by lithography and wet etching as a recognition pattern in the next separation and assembly process. Next, an element isolation auxiliary groove is formed at the element isolation position on the wafer by scribing with a diamond needle or scribing using a laser. Thereafter, braking is performed along the formed element isolation auxiliary grooves to perform primary isolation (primary cleavage). Thereby, the front end surface 100a and the rear end surface 100b are formed. At this time, the other end portion of the optical waveguide extending to the adjacent element regions in the vertical direction remains in the element as a remaining region of the optical waveguide.

Next, as shown in FIG. 3 (e), the rear end face 100b, CVD method or a sputtering method or the like, highly reflective, which is a multilayer dielectric reflective film reflectance is from about 95% for example _SiO 2 / TiO ₂ The rate layer 150 is formed. At this time, the high reflectance layer 150 is also laminated on the third groove portion 132 and the fourth groove portion 142.

  Thereafter, as shown in FIG. 3F, secondary separation (secondary cleavage) is performed in a direction parallel to the longitudinal direction of the resonator, and the cleavage plane 100c is formed, whereby the semiconductor light emitting device 100 is manufactured. Can do. Thereafter, the semiconductor light emitting device 100 is mounted and wired in a desired CAN package. In this way, the semiconductor light emitting device 100 according to this embodiment can be manufactured.

  Next, a preferred example of the semiconductor light emitting device 100 according to this embodiment will be described with reference to FIG. FIG. 4A is a diagram for explaining parameters necessary for the design of the semiconductor light emitting device 100 according to Example 1 of the first embodiment of the present invention, and FIG. 3 is a diagram for explaining a preferable range of parameters in the element 100. FIG.

As shown in FIG. 4A, the acute angle formed between the perpendicular of the first light exit surface 131a and the first optical waveguide 121 is φ1, and the perpendicular of the second light exit surface 141a and the second optical waveguide 122 are used. Is defined as φ2, the angle formed between the first light exit surface 131a and the second light exit surface 141a as γ, and the angle formed between the first optical waveguide 121 and the second optical waveguide 122 as α. And Further, the first optical waveguide 121 the effective refractive index of the second optical waveguide 122 and n _i, the external refractive index of the semiconductor light emitting element 100 and n _a. As described above, the full width at half maximum of the horizontal far-field image in the first outgoing light 121L and the second outgoing light 122L is ω1 and ω2, respectively.

  At this time, an example of a preferable relational expression of these design parameters can be expressed by the following conditional expression.

  That is, in the semiconductor light emitting device 100 according to the present embodiment, in order to satisfy the unimodality of the horizontal far-field image, the horizontal direction of the first outgoing light 121L emitted from the first light outgoing surface 131a is the same. The full width at half maximum ω1 [degree] of the far-field image and the full width at half maximum ω2 [degree] of the far-field image in the horizontal direction in the second outgoing light 122L emitted from the second light exit surface 141a are expressed by the following (formulas): What is necessary is just to set the said parameter so that the relational expression represented by 1) may be satisfied.

  The condition (Condition 1) shown in (Equation 1) is that the first outgoing light 121L emitted from the first light outgoing surface 131a and the second outgoing light 122L emitted from the second light outgoing surface 141a. It represents that the angle formed is smaller than the average of the full width at half maximum (unit is “degree”) of the far-field image in the horizontal direction in each of the first outgoing light 121L and the second outgoing light 122L.

  Thereby, the full width at half maximum (ω1 or ω2) of each of the two intensity peaks is narrower than the width of the average size of the two full widths at half maximum ω1 and ω2, and therefore the first outgoing light 121L and the second outgoing light are obtained. The emitted light when the 122L far-field images are superimposed has a unimodal light intensity distribution. When the full width at half maximum of each of the two intensity peaks is wider than the average width of the full width at half maximum, the far-field images of the first emitted light 121L and the second emitted light 122L are superimposed. In this case, the emitted light has a light intensity distribution having a plurality of peaks.

  More preferably, the above parameters may be set so as to satisfy the following relational expression (Formula 2).

  The condition (Condition 2) shown in (Equation 2) is that the angle formed between the first outgoing light 121L and the second outgoing light 122L is in each of the first outgoing light 121L and the second outgoing light 122L. It represents that it is smaller than half of the average full width at half maximum (unit is “degree”) of the far-field image in the horizontal direction.

  Thereby, even if there is a difference between the light intensity of the first outgoing light 121L and the light intensity of the second outgoing light 122L, the intensity peak of the first outgoing light 121L and the second outgoing light Since the intensity peak of 122L can be made sufficiently close, a horizontal far-field image with good unimodality can be obtained.

FIG. 4B visually shows Condition 1 related to (Expression 1) and Condition 2 related to (Expression 2). Here, in FIG. 4B, the solid curve indicates the boundary line of condition 1, and the broken curve indicates the boundary line of condition 2. By selecting parameters (λ, φ1, φ2) within the range sandwiched by these curves, a light intensity distribution with good unimodality can be obtained. In FIG. 4B, φ1 = φ2, and the effective refractive index of the first optical waveguide 121 and the second optical waveguide 122 is n _i = 2.465, and the refraction outside the semiconductor light emitting device 100 is performed. The rate was n _a = 1.000.

  Here, since the semiconductor light emitting device was actually fabricated and its characteristics were evaluated, the results will be described with reference to FIGS. 4B and 5. FIG. 5A is a diagram showing evaluation characteristics of a horizontal far-field image in an example of the semiconductor light emitting device 100 according to the first embodiment of the present invention, and FIG. 5B to FIG. ) Is a diagram showing evaluation characteristics of a horizontal far-field image in a semiconductor light emitting element according to a comparative example.

  First, as an example of the semiconductor light emitting device 100 according to the present embodiment, the resonator length is 800 μm, the angle α formed by the connection portion of the first optical waveguide 121 and the second optical waveguide 122 is 10 degrees, The one optical waveguide 121 and the second optical waveguide 122 are configured to be line symmetric with respect to the normal to the rear end face 100b. Further, φ1 and φ2 were set to φ1 = φ2 = 3.3 degrees. At this time, γ is 16.7 degrees.

  In addition, as a comparative example, three types in which the value of φ1 was changed with respect to the example of the semiconductor light emitting device 100 according to this embodiment were manufactured. Comparative Examples 1 and 2 both have φ1 (= φ2) set to 5.0 degrees (γ = 0 degrees), and Comparative Example 3 sets φ1 (= φ2) to 10 degrees (γ = 30). Degree).

  As shown in FIG. 4B, it can be seen that in the example of the semiconductor light emitting device 100 according to the present embodiment, parameters within a range with good unimodality are set. Actually, when the evaluation characteristics are calculated, as shown in FIG. 5A, the horizontal far-field image is unimodal, and the symmetry of the far-field image has a good shape with respect to the intensity peak angle. I found out.

  In contrast, in the semiconductor light emitting devices according to Comparative Examples 1 to 3, as shown in FIG. 4B, it is understood that parameters outside the range with good unimodality are set. Actually, when the evaluation characteristics are calculated, as shown in FIGS. 5B to 5D, two light intensity peaks are generated in the horizontal far-field image, and the horizontal far-field image is cracked. It was found that occurred.

  Moreover, although Comparative Example 1 and Comparative Example 2 were produced under the same conditions, as shown in FIGS. 5B and 5C, two light intensity peaks were obtained in the horizontal far-field image. It can be seen that the light intensity is different from each other. That is, it was also found that the element characteristics vary between elements. As described above, the parameter outside the range of the condition shown in FIG. 4B is not suitable as a light source for a display because the far-field image changes greatly for each sample. In the case of the semiconductor light emitting device 100 according to this embodiment configured with parameters within the range of the conditions shown in FIG. 4B, such large variations between the devices did not occur.

  As described above, by setting the parameters (φ1, φ2, γ) within a preferable design range, the light emitted from the semiconductor light emitting device can be unimodal and the semiconductor light emitting device can be stably manufactured. Is possible.

  As described above, according to the semiconductor light emitting device 100 according to the first embodiment of the present invention, the first light exit surface 131 a of the first optical waveguide 121 and the second light exit surface of the second optical waveguide 122. 141a is non-parallel, the angle between the main axis X1 of the first outgoing light 121L and the main axis X2 of the second outgoing light 122L can be controlled. Thereby, the shape of the far field image in the horizontal direction can be controlled by the outgoing light end face of the light emitting element.

  In the present embodiment, the first light exit surface 131a and the second light exit surface 141a are formed so that the main axis X1 of the first outgoing light 121L and the main axis X2 of the second outgoing light 122L approach each other. Therefore, it is possible to realize a semiconductor light emitting device in which the light intensity distribution in the horizontal direction of the far-field image is unimodal.

  Further, by setting φ1 and φ2 to the same size and setting φ1, φ2 and γ within the range of the conditions shown in FIG. 4B, the main axis X1 of the first outgoing light 121L and the second axis The main axis X2 of the emitted light 122L becomes close to parallel. As a result, the emitted light is superimposed on the angle so that the horizontal far-field image becomes a single peak, and the intensity distribution of the horizontal far-field image can be symmetric with respect to the peak intensity angle. .

(Second Embodiment)
Next, a semiconductor light emitting device 200 according to a second embodiment of the present invention will be described with reference to FIG. FIG. 6 is a top view of a semiconductor light emitting device 200 according to the second embodiment of the present invention.

  As shown in FIG. 6, the semiconductor light emitting device 200 according to the second embodiment of the present invention is an SLD having a front end surface 200a and a rear end surface 200b, for example, a ridge stripe, as in the first embodiment. The first optical waveguide 221 and the second optical waveguide 222 are configured as follows. Further, a high reflectivity layer 250 made of a dielectric multilayer film and having a reflectivity of 90% or more is formed on the rear end face 200b.

  The first optical waveguide 221 is a linear optical waveguide having both the front end surface 200a and the rear end surface 200b for emitting the first outgoing light 221L from the light emitting layer. That is, in the present embodiment, unlike the first embodiment, the first light exit surface of the first optical waveguide 221 is configured by a front end surface 200a that is an element isolation surface (cleavage surface).

  On the other hand, as in the first embodiment, the second optical waveguide 222 is linear with the second light emitting surface 241a that emits the second emitted light 222L from the light emitting layer and the rear end surface 200b as both ends. This is an optical waveguide.

  As in the first embodiment, the first optical waveguide 221 and the second optical waveguide 222 are connected at the rear end surface side end portion at the rear end surface 200b, but the front end surface side end portion is connected. It has not been. Note that the first optical waveguide 221 and the second optical waveguide 222 are formed such that the distance between the first optical waveguide 221 and the second optical waveguide 222 increases from the rear end surface 200b where the connection portion is formed toward the front end surface 200a.

  Further, in the semiconductor light emitting device 200 according to the present embodiment, the first groove portion 241 is formed so as to cut out the second optical waveguide 222 in the vicinity of the front end face 200a. An emission surface 241a is formed. A second groove portion 242 is formed so as to cut out the rear end surface 200b. Unlike the first embodiment, no groove is formed at the end of the first optical waveguide 221 on the front end face side.

  As described above, also in the semiconductor light emitting device 200 according to the present embodiment, the front end surface 200a and the second light emission surface 241a which are the first light emission surfaces are the first emission light 221L emitted from the front end surface 200a. The main axis X1 and the main axis X2 of the second outgoing light 222L emitted from the second light exit surface 241a are close to each other so as to be parallel to each other.

  As in the first embodiment, the first groove 241 and the second groove 242 are formed simultaneously when one recess is formed in the adjacent portion of the adjacent element before element isolation. Further, by forming the first optical waveguide 221 and the second optical waveguide 222, the remaining optical waveguide portions 223 and 224 are formed near the front end surface 200a and the rear end surface 200b, respectively. That is, the optical waveguide remaining portions 223 and 224 are formed as the remaining portions of the optical waveguide extending from the adjacent element regions during element isolation. Since the second groove portion 242 and the optical waveguide remaining portions 223 and 224 are not the functional configuration of the semiconductor light emitting device 200, the first optical waveguide 221, the second optical waveguide 222, and the functional configuration of the semiconductor light emitting device 200 are provided. The first groove portion 241 is designed to be disposed at a location different from these functional configurations.

  Note that the cross-sectional configuration and the manufacturing method of the semiconductor light emitting device 200 according to this embodiment are the same as those in the first embodiment, and thus description thereof is omitted.

  Further, as shown in FIG. 6, the acute angle formed by the perpendicular of the first light exit surface (front end surface 200a) and the first optical waveguide 221 is φ1, and the perpendicular of the second light exit surface 241a and the second The acute angle formed by the optical waveguide 222 is φ2, and the full width at half maximum of the horizontal far-field image in the first outgoing light 221L and the second outgoing light 222L is ω1 and ω2, respectively. In addition, an acute angle formed by the first light emitting surface (front end surface 200a) and the second light emitting surface 241a is represented by γ.

  At this time, an example of a preferable relational expression of these design parameters can be expressed by the following conditional expression.

  That is, in the semiconductor light emitting device 200 according to the present embodiment, in order to satisfy the unimodality of the horizontal far-field image, the following relational expressions represented by (Expression 3) and (Expression 4) are satisfied. The above parameters may be set.

  As a result, the emitted light when the far-field images of the first emitted light 221L and the second emitted light 222L are superimposed has a single-peak light intensity distribution.

Here, FIG. 7 shows a preferable parameter range in the above (formula 3) and (formula 4). FIG. 7 is a view for explaining a preferable range of parameters in the semiconductor light emitting device 200 according to the present embodiment. Incidentally, in FIG. _{7, φ1 = φ2, n a} = 2.465, and a _{n i} = 1.000. In FIG. 7, a thin solid line curve indicates a boundary line indicating a preferable range of γ, and a thin broken line curve indicates a boundary line indicating a preferable range of φ2. In addition, the thick solid line and the thick broken line show the center line of a suitable range, respectively.

  As shown in FIG. 7, by selecting parameters (λ, φ1, φ2) within the range between these curves, it is possible to realize a semiconductor light emitting device having a light intensity distribution with good unimodality.

  Here, in the semiconductor light emitting device according to the present invention, the reflectance with respect to the optical waveguide and the tilt angle of the tilted end surface when the guided light is reflected by the tilted end surfaces (the first light emitting surface and the second light emitting surface). The dependency on the above will be described with reference to FIG. FIG. 8 is a graph showing the results of theoretical calculation of the dependence of the reflectivity on the optical waveguide and the tilt angle of the tilted end surface when the guided light is reflected by the tilted end surface in the semiconductor light emitting device according to the present invention. It is.

As shown in FIG. 8, in the semiconductor light emitting device 200 (Invention 2) according to the second embodiment of the present invention, the reflectivity of the first light emitting surface (front end surface 200a) is about 3.3 × 10 ^{−. 5} and the reflectance of the second light exit surface 241a is about 4.2 × 10 ⁻⁷ . Here, since the reflectance of the entire semiconductor light emitting device is represented by the product of the reflectance of the first light emitting surface and the second light emitting surface, the reflectance of the entire semiconductor light emitting device 200 according to the present embodiment. Is about 1.4 × 10 ⁻¹¹ . To be precise, the reflectance of the entire semiconductor light emitting device is represented by the product of the reflectances of the first light emitting surface, the second light emitting surface, and the rear end surface. Since the high reflectivity layer having the same reflectivity is formed on the rear end face, the reflectivity of the entire semiconductor light emitting device is the product of the reflectivity of the first light exit surface and the reflectivity of the second light exit surface. Will be described in

Further, as shown in the figure, for the semiconductor light emitting device 100 (present invention 1) according to the first embodiment of the present invention, the reflectance of the first light emitting surface and the reflectance of the second light emitting surface. Since both are about 2.5 × 10 ⁻³ , the reflectance of the entire semiconductor light emitting device 100 is about 6.2 × 10 ⁻⁶ .

Thus, the semiconductor light emitting device 200 according to the second embodiment, the semiconductor light emitting device 100 according to the first embodiment, it is possible to about ¹⁰⁵ reducing the reflectance of the entire device, further laser Oscillation can be effectively suppressed, and incoherent light with reduced speckle noise can be easily obtained. Further, since the effect of suppressing laser oscillation is increased in this way, the upper limit of the light output that can obtain incoherent light is increased. The reflectance of the inclined end face is qualitatively calculated from the ratio of the light guided through the waveguide and reflected back to the optical waveguide without being emitted from the radiation end face. In addition, since the incident angle and the reflection angle of the light are equal, the light basically does not bounce back in the incident direction. However, since the optical waveguide has a width, of the light reflected by the radiation end face, Some will enter the optical waveguide. The ratio of light returning to the optical waveguide is taken as the reflectance of the inclined end face.

  As described above, according to the semiconductor light emitting device 200 according to the second embodiment of the present invention, the first light exit surface (front end surface 200a) of the first optical waveguide 221 and the second light waveguide 222 are second. The light exit surface 241a is formed in a non-parallel manner so that the main axis X1 of the first outgoing light 221L and the main axis X2 of the second outgoing light 222L approach each other. A semiconductor light emitting device having a single intensity distribution can be realized.

  Furthermore, according to the semiconductor light emitting device 200 according to the present embodiment, incoherent light with reduced speckle noise can be obtained as compared with the semiconductor light emitting device 100 according to the first embodiment.

  In the present embodiment, the first light exit surface of the first optical waveguide 221 is the front end surface 200a (cleaved surface), but the second light exit surface of the second optical waveguide 222 is the front end surface 200a. It doesn't matter. In this case, the first light exit surface of the first optical waveguide 221 is an inclined end surface configured by forming a groove.

(Modification 1 of 2nd Embodiment)
Next, a semiconductor light emitting element 200A according to Modification 1 of the second embodiment of the present invention will be described with reference to FIG. FIG. 9 is a top view of a semiconductor light emitting device according to Modification 1 of the second embodiment of the present invention.

  The semiconductor light emitting device 200A according to this modification has basically the same configuration as the semiconductor light emitting device 200 according to the second embodiment of the present invention described above. Therefore, in FIG. 9, the same components as those shown in FIG. 6 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 9, in the semiconductor light emitting device 200A according to this modification, the second optical waveguide 222A is formed in a curved shape. Specifically, in this modification, the first optical waveguide 221 and the second optical waveguide 222A are configured such that the distance between the rear end surface 200b on which the connection portion is formed is increased toward the front end surface 200a. Although formed, the second optical waveguide 222 </ b> A has a straight portion and a curved portion 222 </ b> R, and is configured so that the spreading width with the first optical waveguide 221 decreases from the middle of the optical waveguide. Yes.

  With this configuration, the semiconductor light emitting element 200A according to the present modification can be made smaller in chip width than in the second embodiment, so that the cost can be reduced.

(Modification 2 of the second embodiment)
Next, a semiconductor light emitting device 200B according to Modification 2 of the second embodiment of the present invention will be described with reference to FIG. FIG. 10 is a top view of a semiconductor light emitting element according to Modification 2 of the second embodiment of the present invention.

  The semiconductor light emitting device 200B according to the present modification has basically the same configuration as the semiconductor light emitting device 200A according to the first modification of the second embodiment of the present invention described above. Therefore, in FIG. 10, the same components as those shown in FIG. 9 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 10, in the semiconductor light emitting device 200B according to the present modification, the second light emitting surface in the second optical waveguide 222A is not a cleaved surface (front end surface 200a), as in the first modification. In the present modification, the first light exit surface 231a of the first optical waveguide 221B is not a cleaved surface (front end surface 200a). That is, in this modification, neither the first optical waveguide 221B nor the second optical waveguide 222A uses a cleaved surface as the light exit surface. The first light exit surface 231a of the first optical waveguide 221B can be formed by forming the first groove 231.

  With this configuration, the semiconductor light emitting element 200B according to this modification can reduce the manufacturing cost.

  In the present modification, the first light exit surface 231a is configured to be substantially parallel to the front end surface 200a, but is not limited thereto. Similarly to the second light emission surface 241a, the second light emission surface 241a may be configured to be inclined with respect to the front end surface 200a.

(Third embodiment)
Next, a semiconductor light emitting device 300 according to a third embodiment of the present invention will be described with reference to FIG. FIG. 11 is a top view of a semiconductor light emitting device 300 according to the third embodiment of the present invention.

  As shown in FIG. 11, a semiconductor light emitting device 300 according to the third embodiment of the present invention is an SLD having a front end surface 300a and a rear end surface 300b, for example, a ridge stripe, as in the first embodiment. The first optical waveguide 321 and the second optical waveguide 322 constituted by the two optical waveguides. Further, a high reflectivity layer 350 having a reflectivity of 90% or more is formed on the rear end face 300b.

  The first optical waveguide 321 is an entirely linear optical waveguide having both the front end face 300a and the rear end face 300b that emit the first emitted light 321L from the light emitting layer as both ends. That is, in the present embodiment, unlike the first embodiment, the first light exit surface of the first optical waveguide 321 is configured by a front end surface 300a that is an element isolation surface (cleavage surface).

  The second optical waveguide 322 is an optical waveguide having both ends of a front end face 300a and a rear end face 300b that emit the second emitted light 322L from the light emitting layer. That is, the second light exit surface of the second optical waveguide 322 is also constituted by the front end surface 300a. Further, the second optical waveguide 322 according to the present embodiment has a bent portion 322v formed in a part of the optical waveguide, and the second optical waveguide 322 has a linear first shape with the bent portion 322v as a boundary. It is comprised by the straight line part 322a and the linear 2nd straight line part 322b.

  In the second optical waveguide 322, a light reflection surface 331a is formed at the bent portion 322v, and the bent portion 322v is connected to the light reflection surface 331a. The light reflecting surface 331a reflects light traveling through the second optical waveguide 322, and the reflected light travels through the second optical waveguide 322 again. The light reflecting surface 331a is formed by forming the first groove 331.

  In the present embodiment, the first optical waveguide 321 and the second optical waveguide 322 are connected at the rear end surface 200b at the rear end surface side, and the front end from the rear end surface 300b on which the connection portion is formed. The distance from the bent portion 322v to the front end surface 300a is formed to be equal to each other up to the bent portion 322v toward the surface 300a. The optical waveguide 322 is configured not to intersect.

  That is, in the present embodiment, if the acute angle formed by the perpendicular of the front end surface 300a and the first optical waveguide 321 is φ1, and the acute angle formed by the normal of the front end surface 300a and the second optical waveguide 322 is φ2, φ1 = It is comprised so that it may become (phi) 2. In the present embodiment, since the first light exit surface and the second light exit surface are parallel, the angle γ formed by the first light exit surface and the second light exit surface is γ = 0. It becomes.

  Further, in the semiconductor light emitting device 300 according to the present embodiment, the first groove portion 331 is formed by cutting out a part of the connection portion between the first straight portion 322a and the second straight portion 322b in the second optical waveguide 322. Is formed. Furthermore, in the present embodiment, the second groove portion 332 is formed, and the first groove portion 331 and the second groove portion 332 form one recess with respect to the adjacent portion of the adjacent element before element isolation. Are formed at the same time. Further, by forming the first optical waveguide 321 and the second optical waveguide 322, the remaining optical waveguide portions 323 and 324 are formed in the vicinity of the rear end face 300b. In other words, the optical waveguide remaining portions 323 and 324 are formed as the remaining portion of the optical waveguide extending from the adjacent element region during element isolation. Since the second groove portion 332 and the optical waveguide remaining portions 323 and 324 are not the functional configuration of the semiconductor light emitting device 300, the first optical waveguide 321, the second optical waveguide 322, and the functional configuration of the semiconductor light emitting device 300 are provided. The first groove portion 331 is designed to be disposed at a location different from these functional configurations.

  The cross-sectional configuration of the semiconductor light emitting device 300 according to this embodiment is the same as that of the first embodiment, and a description thereof will be omitted.

  Next, a method for manufacturing the semiconductor light emitting device 300 according to the third embodiment of the present invention will be described with reference to FIGS. FIG. 12A to FIG. 12E are diagrams for explaining each step in the method for manufacturing a semiconductor light emitting element according to the third embodiment of the present invention. FIG. 12 shows a part of the wafer as in FIG. 3, and the case where a total of nine semiconductor light emitting elements 100 of three rows in the vertical direction and three rows in the horizontal direction are formed on the wafer will be described. . In FIG. 12, a broken line represents a chip region of one semiconductor light emitting element 300.

  The semiconductor light emitting device 300 according to this embodiment can be basically manufactured in the same manner as in the first embodiment shown in FIG. Therefore, detailed description is omitted.

  First, after forming a laminated structure made of a nitride semiconductor on a substrate, a first optical waveguide 321 and a second optical waveguide 322 are formed as shown in FIG. At this time, both ends of the first optical waveguide 321 and the second optical waveguide 322 extend to the adjacent element regions in the vertical direction so that the optical waveguide is not cut off when the elements are separated. Has been formed. Furthermore, in the present embodiment, the second optical waveguide 322 is formed to extend to the adjacent element regions in the lateral direction so that the second optical waveguide 322 is not cut off in the vicinity of the bent portion 322v. Has been.

Next, as shown in FIG. 12B, a first groove 331 and a second groove 332 are formed in order to form the light reflecting surface 331a. At this time, after the SiO ₂ film is deposited, the light reflecting surface 331a is formed only in a region where the concave portion 330 composed of the first groove portion 331 and the second groove portion 332 is formed by dry etching using photolithography and RIE. The SiO ₂ film is removed. Thereafter, the recess is formed by ICP (Inductively Coupled Plasma) dry etching using Cl ₂ gas or SiCl ₄ gas using the SiO ₂ film as a mask. Thereby, the light reflection surface 331a is formed. At this time, the recess 330 is formed so as to cut out the optical waveguide extending to the adjacent element regions in the horizontal direction. In other words, the second groove 332 is formed to cut out the optical waveguide extending to the adjacent element region.

  Next, as shown in FIG. 12C, primary separation (primary cleavage) is performed in which the semiconductor light emitting elements are divided from the wafer into a bar state that is connected in a horizontal row. Thereby, the front end surface 300a and the rear end surface 300b of the semiconductor light emitting element 300 are formed. Thereafter, a laminated film for improving the reliability of the SLD may be formed on the first light emitting surface and the front end surface 300a which is the second light emitting surface.

Next, as shown in FIG. 12 (d), the rear end face 300b is a high-reflection film that is a multilayer dielectric reflection film made of, for example, SiO ₂ / TiO ₂ having a reflectivity of about 95% by CVD or sputtering. The rate layer 350 is formed.

  After that, as shown in FIG. 12E, secondary separation (secondary cleavage) is performed in a direction parallel to the longitudinal direction of the resonator to form the cleavage plane 300c, thereby manufacturing the semiconductor light emitting device 300. Can do. In this way, the semiconductor light emitting device 300 according to this embodiment can be manufactured.

  As described above, according to the semiconductor light emitting device 300 according to the third embodiment of the present invention, the bent portion 322v having the total reflection surface is formed in the second optical waveguide 322, and φ1 = φ2. Since it is configured, the main axis (optical axis) of the first outgoing light emitted from the first optical waveguide 321 and the main axis (optical axis) of the second outgoing light emitted from the second optical waveguide 322 are brought closer to each other. Therefore, the horizontal far-field image in the emitted light of the entire semiconductor light emitting element can be unimodal, and the chip width can be reduced, so that the cost can be reduced.

  Note that the range of a suitable parameter such as φ1 for obtaining a horizontal far-field image with good unimodality is the same as that in the first embodiment, and thus the description thereof is omitted.

Further, the first optical waveguide 321 the effective refractive index of the second optical waveguide 322 and n _i, the refractive index at the outside of the semiconductor light emitting element 300 and n _a, the light reflecting surface 331a perpendicular and the second straight line The acute angle formed by the portion 322b is preferably larger than arcsin (n _a / n _i ).

  Thereby, since the light reflection surface 331a can be made into a total reflection surface, a reflectance can be brought close to 100% infinitely. Therefore, a process for manufacturing a semiconductor layer having a high reflectance with respect to the light reflecting surface is not required, and a manufacturing cost for forming the end surface is not required.

(Modification of the third embodiment)
Next, a semiconductor light emitting device 300A according to a modification of the third embodiment of the present invention will be described with reference to FIG. FIG. 13 is a top view of a semiconductor light emitting device according to a modification of the third embodiment of the present invention.

  A semiconductor light emitting element 300A according to this modification has basically the same configuration as the semiconductor light emitting element 300 according to the third embodiment of the present invention described above. Therefore, in FIG. 13, the same components as those shown in FIG. 11 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 13, in the semiconductor light emitting device 300A according to this modification, the second optical waveguide 322A is formed in a curved shape. Specifically, in the present modification, the first optical waveguide 321 and the second optical waveguide 322A are configured such that the distance between the rear end surface 300b where the connection portion is formed is increased toward the front end surface 300a. Although formed, the second optical waveguide 322A has a straight portion and a curved portion 322R, and is configured so that the distance from the first optical waveguide 321 becomes equal from the middle. In the vicinity of 300a, φ1 = φ2.

  With this configuration, the semiconductor light emitting element 300A according to the present modification can reduce the chip width, thereby reducing the cost.

(Fourth embodiment)
Next, a semiconductor light emitting device 400 according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 14 is a top view of a semiconductor light emitting device 400 according to the fourth embodiment of the present invention.

  As shown in FIG. 14, the semiconductor light emitting device 400 according to the fourth embodiment of the present invention is an SLD having a front end surface 400a and a rear end surface 400b, for example, a ridge stripe, as in the first embodiment. The first optical waveguide 421 and the second optical waveguide 422 are configured as follows. Further, similarly to the other embodiments, a high reflectance layer 450 having a reflectance of 90% or more is formed on the rear end surface 400b.

  The first optical waveguide 421 is an optical waveguide having both ends of a first light emission surface 431a and a rear end surface 400b that emit the first emission light 421L, and has a linear shape and a curved portion 421R. This is an optical waveguide. The second optical waveguide 422 is also an optical waveguide having both ends of the second light exit surface 441a and the rear end surface 400b for emitting the second exit light 422L, and has a straight line portion and a curved portion 422R. This is an optical waveguide.

  As in the first embodiment, the first optical waveguide 421 and the second optical waveguide 422 are connected at the rear end surface side at the rear end surface 400b, but the front end surface side end is connected. It has not been. Further, the first optical waveguide 421 and the second optical waveguide 422 are formed such that the distance between the first optical waveguide 421 and the second optical waveguide 422 increases from the rear end surface 400b where the connection portion is formed toward the front end surface 400a. In addition, the first optical waveguide 421 and the second optical waveguide 422 are configured to be line-symmetric with respect to the perpendicular of the connection portion of the rear end surface 400b.

  In the semiconductor light emitting device 400 according to the present embodiment, the first groove portion 431 is formed so as to cut out the first optical waveguide 421 in the vicinity of the front end surface 400a, and the second optical waveguide 422 is cut out. Thus, the second groove portion 441 is formed. Thereby, the 1st light-projection surface 431a and the 2nd light-projection surface 441a are formed. Further, a third groove portion 432 and a fourth groove portion 442 are formed so as to cut out the rear end surface 400b.

  Note that the first groove portion 431 and the third groove portion 432 are formed at the same time when one recess is formed, and the second groove portion 441 and the fourth groove portion 442 are adjacent to each other before element isolation. It is formed simultaneously with the formation of one recess for the adjacent portion of the element. Further, by forming the first optical waveguide 421 and the second optical waveguide 422, the optical waveguide remaining portion 423 is formed in the vicinity of the front end face 400a. That is, the optical waveguide remaining portion 423 is formed as the remaining portion of the optical waveguide extending from the adjacent element region at the time of element isolation. Since the third groove portion 432, the fourth groove portion 442, and the optical waveguide remaining portion 423 are not the functional configuration of the semiconductor light emitting device 400, the first optical waveguide 421, which is the functional configuration of the semiconductor light emitting device 400, the second The optical waveguide 422, the first groove portion 431, and the second groove portion 441 are designed so as to be disposed at a location different from these functional configurations.

  In the semiconductor light emitting device 400 according to the present embodiment, the first light emitting surface 431a and the second light emitting surface 441a are formed in parallel to each other and inclined with respect to the front end surface 400a. And formed non-parallel. That is, in this embodiment, the acute angle formed by the perpendicular of the first light exit surface 431a and the first optical waveguide 421 is φ1, and the perpendicular of the second light exit surface 441a and the second optical waveguide 422 are formed. When the acute angle is φ2, φ1 = φ2. In the present embodiment, the angle γ formed by the first light exit surface and the second light exit surface is γ = 0.

  Note that the cross-sectional configuration and the manufacturing method of the semiconductor light emitting device 400 according to this embodiment are the same as those in the first embodiment, and thus description thereof is omitted.

  As described above, according to the semiconductor light emitting device 400 according to the fourth embodiment of the present invention, the first optical waveguide 421 and the second optical waveguide 422 have the curved portions 421R and 422R, The light emitting surface 431a and the second light emitting surface 441a are formed non-parallel to the front end surface 400a. Thereby, since the chip width can be reduced, the cost can be reduced and the manufacturing cost by cleavage can be reduced.

  Note that the range of a suitable parameter such as φ1 for obtaining a horizontal far-field image with good unimodality is the same as that in the first embodiment, and thus the description thereof is omitted.

  As mentioned above, although the semiconductor light-emitting device which concerns on this invention was demonstrated based on embodiment and a modification, this invention is not limited to these embodiment and a modification. Unless it deviates from the meaning of this invention, the form which carried out the various deformation | transformation which those skilled in the art can consider to this embodiment, or the structure constructed | assembled combining the component in a different embodiment or modification is also included in the scope of the present invention. It is.

  INDUSTRIAL APPLICABILITY The present invention is useful as a structure of a semiconductor light emitting device that can control the light emission direction and the shape control of the light intensity distribution of a horizontal far-field image. It is widely useful as a semiconductor light emitting device for the purpose of improving the symmetry of light intensity distribution.

100, 200, 200A, 200B, 300, 300A, 400, 900 Semiconductor light emitting device 100L Emission light 100a, 200a, 300a, 400a, 900a Front end surface 100b, 200b, 300b, 400b, 900b Rear end surface 100c, 300c Cleaved surface 101 Substrate 102 n-type cladding layer 103 n-type guide layer 104 active layer (light emitting layer)
105 p-type guide layer 106 carrier overflow suppression layer (OFS layer)
107 p-type cladding layer 108 p-side electrode 109 wiring electrode 110 block layer 111 n-side electrode 121, 221, 221B, 321, 321A, 421, 921 first optical waveguide 121L, 221L, 321L, 421L first outgoing light 122 222, 222A, 322, 322A, 422, 922 Second optical waveguide 122L, 222L, 322L, 422L Second outgoing light 123, 223, 224, 323, 324, 423 Remaining optical waveguide 130, 140 Recess 131, 231 241, 331, 431 First groove 131a, 231a, 431a First light exit surface 132, 432 Third groove 141, 242, 332, 441 Second groove 141a, 241a, 441a Second light exit surface 142, 442 Fourth groove 150, 250, 350, 4 50 High reflectivity layer 222R, 322R, 421R, 422R Curved part 322v Bent part 322a First straight part 322b Second straight part 331a Light reflecting surface 950 Reflecting film

Claims (17)

A semiconductor light emitting device having a light emitting layer,
A first optical waveguide having both ends of a first light emitting surface for emitting the first light from the light emitting layer and a rear end surface for reflecting the light from the light emitting layer;
A second light emitting surface that emits second light from the light emitting layer and a second optical waveguide having both ends of the rear end surface;
The first optical waveguide and the second optical waveguide are connected at the rear end surface,
The first light emitting surface and the second light emitting surface are non-parallel to each other such that the optical axis of the first light and the optical axis of the second light are close to each other. An acute angle formed by the perpendicular of the first light exit surface and the first optical waveguide is φ1,
An acute angle formed by the perpendicular of the second light exit surface and the second optical waveguide is φ2,
The angle formed by the first light exit surface and the second light exit surface is γ,
The effective refractive index of said second optical waveguide and said first optical waveguide and n _i,
The refractive index outside the semiconductor light emitting device is denoted by _na ,
The full width at half maximum of the horizontal far-field image in the first light emitted from the first light exit surface is ω1,
When the full width at half maximum of the horizontal far-field image in the second light emitted from the second light exit surface is ω2,

The semiconductor light emitting device according to claim 1, wherein the relationship is satisfied. 3. The semiconductor light emitting element according to claim 1, wherein a connection portion between the first optical waveguide and the second optical waveguide on the rear end surface is axisymmetric with respect to a normal to the rear end surface. The semiconductor light emitting element according to claim 1, wherein the first optical waveguide and the second optical waveguide are each formed in a linear shape. At least one of the first optical waveguide and the second optical waveguide has a curved portion;
The semiconductor light-emitting device according to claim 1, wherein the first optical waveguide and the second optical waveguide do not intersect with each other. The semiconductor light emitting element according to claim 1, wherein at least one of the first light emitting surface and the second light emitting surface is a cleaved surface. The semiconductor light emitting element according to claim 1, wherein at least one of the first light emitting surface and the second light emitting surface is formed by a groove. A semiconductor light emitting device having a light emitting layer,
A first optical waveguide having both ends of a first light emitting surface for emitting the first light from the light emitting layer and a rear end surface for reflecting the light from the light emitting layer;
A second light emitting surface that emits second light from the light emitting layer and a second optical waveguide having both ends of the rear end surface;
The first optical waveguide and the second optical waveguide are connected at the rear end surface,
The first light exit surface and the second light exit surface are parallel,
An acute angle formed by the perpendicular of the first light exit surface and the first optical waveguide is φ1,
An acute angle formed by the perpendicular of the second light exit surface and the second optical waveguide is φ2,
The effective refractive index of said second optical waveguide and said first optical waveguide and n _i,
The refractive index outside the semiconductor light emitting device is denoted by _na ,
The full width at half maximum of the horizontal far-field image in the first light emitted from the first light exit surface is ω1,
When the full width at half maximum of the horizontal far-field image in the second light emitted from the second light exit surface is ω2,

A semiconductor light emitting device satisfying the relationship. The semiconductor light emitting element according to claim 8, wherein a connection portion between the first optical waveguide and the second optical waveguide on the rear end surface is axisymmetric with respect to a normal to the rear end surface. The semiconductor light emitting element according to claim 8, wherein at least one of the first optical waveguide and the second optical waveguide has a curved portion. The semiconductor light emitting element according to claim 8, wherein the first optical waveguide and the second optical waveguide are line symmetric with respect to a perpendicular to the rear end surface. The semiconductor light emitting element according to any one of claims 8 to 11, wherein at least one of the first optical waveguide and the second optical waveguide has a bent portion. The semiconductor light emitting element according to claim 12, wherein the bent portion is connected to a light reflecting surface that reflects light. The semiconductor light emitting element according to claim 13, wherein the light reflecting surface is formed by a groove formed in the vicinity of the bent portion. The optical waveguide having the bent portion has a first straight portion on the light emitting side and a second straight portion on the rear end face side with the bent portion as a boundary,
Acute angle normal of the light reflecting surface and the second straight portions, the semiconductor light emitting device according to claim 13 or 14 greater than _{arcsin (n a / n i)} . The semiconductor light emitting element according to any one of claims 8 to 15, wherein at least one of the first light emitting surface and the second light emitting surface is a cleaved surface. The semiconductor light emitting element according to any one of claims 8 to 15, wherein at least one of the first light emitting surface and the second light emitting surface is formed by a groove.

Images