JP2011108741A - Light emitting device and projector - Google Patents

Abstract

Provided is a light-emitting element capable of causing light emitted from a plurality of gain regions to travel in the same direction or focusing direction with low loss.
In the light emitting device according to the present invention, the relative refractive index difference Δ of the active layer with respect to the guide portion satisfies the following formula (1), and the end surface 172 of the first gain region 160 on the second surface 107 side. The light 20 emitted from the second gain region 162 and the light 22 emitted from the end surface 176 on the second surface 107 side of the second gain region 162 travel in the same direction or in a converging direction.
0.05 [% / μm] ≦ (Δ / W) (1)
However, W is 5 μm or more, R is 1600 μm or more, and Δ is represented by the following formula (2).
Δ = (n _core ² −n _clad ² ) / n _core ² (2)
Here, n _core is an effective refractive index of the vertical section of the multilayer structure including the bending gain portion, and n _clad is an effective refractive index of the vertical section of the multilayer structure including the guide portion.
[Selection] Figure 1

Description

  The present invention relates to a light emitting element and a projector.

  A super luminescent diode (hereinafter also referred to as “SLD”) is incoherent like a normal light emitting diode and has a broad spectrum shape, but has a single optical output characteristic similar to that of a semiconductor laser. This is a semiconductor light emitting device capable of obtaining an output up to about several hundreds mW. Similar to a semiconductor laser, SLD uses a mechanism in which spontaneously emitted light generated by recombination of injected carriers is amplified by receiving a high gain due to stimulated emission while traveling in the direction of the light emitting end face, and is emitted from the light emitting end face. ing. However, unlike a semiconductor laser, an SLD needs to suppress the formation of a resonator due to end surface reflection and prevent laser oscillation.

  As a method for suppressing laser oscillation, for example, as shown in Patent Document 1, a configuration in which a gain region (optical waveguide) is inclined from an emission end face is known. In Patent Document 1, two linear optical waveguides that are inclined from the emission end face are formed in order to increase the output.

JP 2007-165688 A

  As described above, in a light emitting device including a linear optical waveguide (gain region) inclined from the emission end face, light emitted from a plurality of gain regions may travel in the direction of diffusion. However, in order to realize a light source with a small light output and etendue, it is desirable that light emitted from a plurality of gain regions travel in the same direction or in a converging direction.

  One of the objects according to some aspects of the present invention is to provide a light emitting element capable of causing light emitted from a plurality of gain regions to travel in the same direction or in a converging direction with low loss. is there. Another object of some embodiments of the present invention is to provide a projector having the light-emitting element.

The light emitting device according to the present invention is
A laminated structure having a first cladding layer, a second cladding layer, and an active layer sandwiched between the first cladding layer and the second cladding layer;
At least a part of the active layer constitutes a first gain region and a second gain region serving as a current path of the active layer,
In the laminated structure, the first surface and the second surface of the exposed surfaces of the active layer are in a positional relationship facing each other.
In the wavelength band of light generated in the first gain region and the second gain region, the reflectance of the first surface is higher than the reflectance of the second surface,
The first gain region and the second gain region are provided from the first surface to the second surface,
The end surface on the first surface side of the first gain region and the end surface on the first surface side of the second gain region overlap on the first surface,
The first gain region is provided in a straight line, as viewed in plan from the stacking direction of the active layer, and inclined in a clockwise direction with respect to the normal of the first surface;
The second gain region is a plan view from the stacking direction of the active layer,
A first gain section provided linearly from the first surface and inclined in a counterclockwise direction with respect to a perpendicular to the first surface;
A bending gain portion having a width W and a radius of curvature R connected to the first gain portion;
Have
The bending gain portion is sandwiched between guide portions having a refractive index smaller than that of the active layer in plan view from the stacking direction of the active layer,
The relative refractive index difference Δ with respect to the guide portion of the active layer satisfies the following formula (1):
The light emitted from the end surface on the second surface side of the first gain region and the light emitted from the end surface on the second surface side of the second gain region travel in the same direction or in a converging direction. .

0.05 [% / μm] ≦ (Δ / W) (1)
However, W is 5 μm or more, R is 1600 μm or more, and Δ is represented by the following formula (2).

Δ = (n _core ² −n _clad ² ) / n _core ² (2)
Here, n _core is an effective refractive index of the vertical section of the multilayer structure including the bending gain portion, and n _clad is an effective refractive index of the vertical section of the multilayer structure including the guide portion.

  According to such a light emitting element, light emitted from the first gain region and the second gain region can be made to travel in the same direction or in a converging direction with low loss.

In the light emitting device according to the present invention,
The guide part may be a SiN layer.

  According to such a light emitting element, the light emitted from the first gain region and the second gain region is in the same direction or a direction in which the light is emitted with lower loss than in the case where the guide portion is not formed of an SiN layer. Can proceed to. In addition, when forming the bent gain portion, it is possible to prevent exposure of a portion that has been subjected to process damage (damage to the side surface when etching, etc.) and to allow moisture to enter the bent gain portion from the outside. Can also be prevented. That is, it also functions as a passivation film.

In the light emitting device according to the present invention,
The guide part is a laminate of a SiN layer and a polyimide layer,
The bend gain portion may be in contact with the SiN layer.

  According to such a light emitting element, when it is difficult to form the guide portion made of a single SiN layer in terms of film thickness (it takes time to form a film), the guide can be easily (in a short time). In the same direction or in the direction of focusing the light emitted from the first gain region and the second gain region with lower loss than when the guide portion is formed of air. Can be advanced.

In the light emitting device according to the present invention,
The guide part may be air.

  According to such a light emitting element, the guide portion can be formed by the simplest process, and the first gain region and the second gain can be reduced with a low loss compared to the case where the guide portion is not formed. Light emitted from the gain region can be emitted in the same direction or in a converging direction.

In the light emitting device according to the present invention,
The second gain region is a plan view from the stacking direction of the active layer,
A second gain portion may be further provided, which is provided in a straight line from the bending gain portion to the second surface and inclined in a clockwise direction with respect to the normal of the first surface.

  According to such a light emitting element, light emitted from the first gain region and the second gain region can be made to travel in the same direction or in a converging direction with low loss.

In the light emitting device according to the present invention,
The second gain region may have a plurality of bending gain portions.

  According to such a light emitting element, light emitted from the first gain region and the second gain region can be made to travel in the same direction or in a converging direction with low loss.

In the light emitting device according to the present invention,
The bending gain portion may have an arc shape in plan view from the stacking direction of the active layer.

  According to such a light emitting element, light emitted from the first gain region and the second gain region can be made to travel in the same direction or in a converging direction with low loss.

The projector according to the present invention is
A light emitting device having the light emitting element according to the present invention;
A light modulation device that modulates light emitted from the light emitting device according to image information;
A projection device for projecting an image formed by the light modulation device;
including.

  According to such a projector, since the light emitting element according to the present invention is provided, a light source with high output and low etendue can be realized. Thereby, size reduction and high brightness can be achieved.

The top view which shows typically the light emitting element which concerns on 1st Embodiment. FIG. 3 is a cross-sectional view schematically showing the light emitting element according to the first embodiment. FIG. 3 is a cross-sectional view schematically showing the light emitting element according to the first embodiment. Sectional drawing which shows typically the manufacturing process of the light emitting element which concerns on 1st Embodiment. Sectional drawing which shows typically the manufacturing process of the light emitting element which concerns on 1st Embodiment. Sectional drawing which shows typically the manufacturing process of the light emitting element which concerns on 1st Embodiment. Sectional drawing which shows typically the light emitting element which concerns on the 1st modification of 1st Embodiment. Sectional drawing which shows typically the light emitting element which concerns on the 2nd modification of 1st Embodiment. Sectional drawing which shows typically the light emitting element which concerns on the 3rd modification of 1st Embodiment. The top view which shows typically the light emitting element which concerns on the 4th modification of 1st Embodiment. The top view which shows typically the model used for the experiment example of the light emitting element which concerns on 1st Embodiment. The graph which shows the result of the experiment example of the light emitting element which concerns on 1st Embodiment. The graph which shows the result of the experiment example of the light emitting element which concerns on 1st Embodiment. FIG. 6 is a diagram schematically illustrating a projector according to a second embodiment. Sectional drawing which shows typically the light-emitting device used for the projector which concerns on 2nd Embodiment.

1. 1. First embodiment 1.1. First, a light-emitting device according to a first embodiment will be described with reference to the drawings. FIG. 1 is a plan view schematically showing the light emitting device 100. 2 is a cross-sectional view taken along the line II-II of FIG. 3 is a cross-sectional view taken along the line III-III of FIG. In FIG. 1, the second electrode 114 is not shown for convenience. Here, a case where the light emitting element 100 is an InGaAlP-based (red) SLD will be described. Unlike a semiconductor laser, an SLD can prevent laser oscillation by suppressing the formation of a resonator due to end face reflection. Therefore, speckle noise can be reduced.

  As illustrated in FIGS. 1 to 3, the light emitting element 100 includes a laminated structure 120 and a guide portion 117. The laminated structure 120 can include a substrate 102, a first cladding layer 104, an active layer 106, a second cladding layer 108, and a contact layer 110. The light emitting device 100 may further include a first electrode 112, a second electrode 114, and an insulating part 116.

  As the substrate 102, for example, a first conductivity type (for example, n-type) GaAs substrate or the like can be used.

  The first cladding layer 104 is formed on the substrate 102. As the first cladding layer 104, for example, an n-type AlGaInP layer can be used. Although not shown, a buffer layer may be formed between the substrate 102 and the first cladding layer 104. As the buffer layer, for example, an n-type GaAs layer, an InGaP layer, or the like can be used. The buffer layer can improve the crystallinity of the layer formed thereabove.

  The active layer 106 is formed on the first cladding layer 104. The active layer 106 is sandwiched between the first cladding layer 104 and the second cladding layer 110. The active layer 106 has, for example, a multiple quantum well (MQW) structure in which three quantum well structures each composed of an InGaP well layer and an InGaAlP barrier layer are stacked.

  The shape of the active layer 106 is, for example, a rectangular parallelepiped (including a cube). The active layer 106 has a first surface 105 and a second surface 107 as shown in FIG. The first surface 105 and the second surface 107 are surfaces that are not in contact with the first cladding layer 104 or the second cladding layer 110 among the surfaces of the active layer 106, and are exposed surfaces in the layer structure 120. . It can be said that the first surface 105 and the second surface 107 are side surfaces of the active layer 106. The first surface 105 and the second surface 107 face each other and are parallel in the illustrated example.

  A part of the active layer 106 constitutes a first gain region 160 and a second gain region 162. The first gain region 160 and the second gain region 162 may form a gain region pair 168. Each of the gain regions 160 and 162 is provided from the first surface 105 toward the second surface 107 as shown in FIG. Although not shown, a plurality of gain region pairs 168 may be provided.

The gain regions 160 and 162 can generate light, which can receive gain within the gain regions 160 and 162. In the wavelength band of light generated in the gain regions 160 and 162, the reflectance of the first surface 105 is higher than the reflectance of the second surface 107. For example, a high reflectance can be obtained by covering the first surface 105 with the reflecting portion 130. The reflection unit 130 is, for example, a dielectric multilayer mirror. Specifically, as the reflection unit 130, for example, a mirror in which 10 pairs are stacked in the order of the SiO ₂ layer and the Ta ₂ O ₅ layer from the first surface 105 side can be used. The reflectance of the first surface 105 is desirably 100% or close thereto. On the other hand, the reflectance of the second surface 107 is preferably 0% or close thereto. For example, a low reflectance can be obtained by covering the second surface 107 with the antireflection portion 132. As the antireflection part 132, for example, an Al ₂ O ₃ single layer or the like can be used. As the reflecting portion 130 and the anti-reflection portion 132, but is not limited to the example described above, for example, _Al 2 _{O 3} layer, TiN layer, TiO ₂ layer, SiON layer, and the SiN layer, these multilayer films Etc. can be used.

  The first gain region 160 has a first end surface 170 provided on the first surface 105 and a second end surface 172 provided on the second surface 107. The planar shape of the first gain region 160 is, for example, a parallelogram as shown in FIG. The first gain region 160 is provided linearly from the first end surface 170 to the second end surface 172 in a direction inclined with respect to the normal line P of the first side surface 105. Thereby, the laser oscillation of the light generated in the gain region 160 can be suppressed or prevented.

  As shown in FIG. 1, the second gain region 162 has a third end surface 174 provided on the first surface 105 and a fourth end surface 176 provided on the second surface 107. The second gain region 162 is provided from the third end surface 174 to the fourth end surface 176. In the illustrated example, the first end surface 170 and the third end surface 174 completely overlap with each other on the overlapping surface 178. The second gain region 162 may include a first gain unit 163, a second gain unit 164, and a bending gain unit 166.

The first gain unit 163 has a third end surface 174. The planar shape of the first gain unit 163 is, for example, a parallelogram. The first gain portion 163 is provided in a straight line from the third end surface 174 to the bending gain portion 166 connected to the first gain portion 163, in a direction inclined with respect to the normal line P of the first surface 105. Yes. The direction in which the first gain section 163 extends (the direction in which it extends) is different from the direction in which the first gain region 160 extends. More specifically, the first gain portion 163 is counterclockwise with respect to the perpendicular P in a plan view from the stacking direction of the active layer 106 (as viewed in the film thickness direction of the active layer 106) as shown in FIG. Inclined in the direction. As shown in FIG. 1, the first gain region 160 is provided so as to be inclined in the clockwise direction with respect to the perpendicular line P in plan view from the stacking direction of the active layer 106. It can be said that the first gain portion 163 is provided to be inclined to one side with respect to the perpendicular P, and the first gain region 160 is provided to be inclined to the other side with respect to the perpendicular P. In the illustrated example, the angle θ ₁ with respect to the perpendicular P of the first gain region 160 and the angle θ ₂ with respect to the perpendicular P of the first waveguide portion 163 are the same size. In the present invention, when the term “angle” is used, if there are an acute angle and an obtuse angle, the “angle” indicates an acute angle.

The second gain unit 164 has a fourth end surface 176. The planar shape of the second gain unit 164 is, for example, a parallelogram. The second gain portion 164 is provided linearly from the bending gain portion 166 connected to the second gain portion 164 to the fourth end surface 176 in a direction inclined with respect to the normal line P of the first surface 105. Yes. In the illustrated example, the extending direction of the second gain unit 164 is the same as the extending direction of the first gain region 160. That is, in the illustrated example, the angle θ ₃ with respect to the perpendicular P of the second gain unit 164 and the angle θ ₁ are the same size. Although not shown, the angle θ ₃ may be larger than the angle θ ₁ . Thereby, the light 20 emitted from the second end surface 172 and the light 22 emitted from the fourth end surface 176 can travel in the same direction or in a converging direction.

  The bending gain unit 166 can be provided between the first gain unit 163 and the second gain unit 164. The bending gain unit 166 is connected to the first gain unit 163 and the second gain unit 164, and is provided with a constant width W from the first gain unit 163 to the second gain unit 164. In the example shown in FIG. 1, the first gain region 160 and the second gain region 162 are also provided with a constant width W. The bent waveguide portion 166 may have an arc shape having a radius of curvature R. As a result, the second gain region 162 is bent, and the light 22 emitted from the fourth end face 176 can travel in the same direction as the light 20 emitted from the second end face 172 or in a converging direction. That is, the second gain region 162 is not bent by, for example, a side surface of the active layer or a reflection surface provided inside. As shown in FIG. 1, the bending gain portion 166 can be separated from the outer periphery of the active layer 106 in plan view from the stacking direction of the active layer 106. The bent gain portion 166 can prevent the light generated in the second gain region 162 from being directly multiple-reflected between the third end surface 174 and the fourth end surface 176. As a result, since a direct resonator cannot be formed, laser oscillation of light generated in the second gain region 162 can be suppressed or prevented.

  As shown in FIGS. 2 and 3, the second cladding layer 108 is formed on the active layer 106. As the second cladding layer 108, for example, a second conductivity type (for example, p-type) AlGaInP layer or the like can be used.

  For example, the p-type second cladding layer 108, the active layer 106 not doped with impurities, and the n-type first cladding layer 104 constitute a pin diode. Each of the first cladding layer 104 and the second cladding layer 108 is a layer having a larger forbidden band width and a smaller refractive index than the active layer 106. The active layer 106 has a function of amplifying light. The first cladding layer 104 and the second cladding layer 108 have a function of confining injected carriers (electrons and holes) and light with the active layer 106 interposed therebetween.

  In the light emitting element 100, when a forward bias voltage of a pin diode is applied between the first electrode 112 and the second electrode 114, recombination of electrons and holes occurs in the gain regions 160 and 162 of the active layer 106. This recombination causes light emission. With this generated light as a starting point, stimulated emission occurs in a chain, and the light intensity is amplified in the gain regions 160 and 162. For example, as shown in FIG. 1, a part of the light 10 generated in the first gain region 160 is amplified in the first gain region 160, then reflected on the overlapping surface 178, and the second gain region 162. Although it is emitted as the emitted light 22 from the four end faces 176, the light intensity is amplified also in the second gain region 162 after reflection. Similarly, part of the light generated in the second gain region 162 is amplified in the second gain region 162, then reflected on the overlapping surface 178, and emitted light 20 from the second end surface 172 of the first gain region 160. The light intensity is amplified also in the first gain region 160 after reflection. Some of the light generated in the first gain region 160 is directly emitted from the second end face 172 as the emitted light 20. Similarly, some of the light generated in the second gain region 162 is emitted directly from the fourth end face 176 as the emitted light 22. These lights are similarly amplified in the gain regions 160 and 162.

  The contact layer 110 is formed on the second cladding layer 108 as shown in FIG. As the contact layer 110, a layer in ohmic contact with the second electrode 114 can be used. As the contact layer 110, for example, a p-type GaAs layer can be used.

  The contact layer 110 and a part of the second cladding layer 108 can form a columnar portion 111. The planar shape of the columnar portion 111 is the same as that of the gain regions 160 and 162. For example, the current path between the electrodes 112 and 114 is determined by the planar shape of the columnar portion 111, and as a result, the planar shape of the gain regions 160 and 162 is determined. Although not shown, the side surface of the columnar portion 111 can be inclined.

As shown in FIG. 2, the insulating part 116 can be provided on the second cladding layer 108 and on the side of the columnar part 111. The insulating part 116 can be in contact with the side surface of the columnar part 111. However, the insulating portion 116 is not formed on the side of the columnar portion 113 (see FIG. 3) including the bending gain portion 166. The upper surface of the insulating part 116 is continuous with the upper surface of the contact layer 110, for example, as shown in FIG. As the insulating part 116, for example, a SiN layer, a SiO ₂ layer, a polyimide layer, or the like can be used. When these materials are used as the insulating portion 116, the current between the electrodes 112 and 114 can flow through the columnar portion 111 sandwiched between the insulating portions 116, avoiding the insulating portion 116. The insulating part 116 may have a refractive index smaller than that of the active layer 106. In this case, the effective refractive index of the vertical cross section of the portion where the insulating portion 116 is formed is smaller than the effective refractive index of the vertical cross section of the portion where the insulating portion 116 is not formed, that is, the portion where the columnar portion 116 is formed. Thereby, light can be efficiently confined in the gain regions 160 and 162 in the planar direction. Note that although not illustrated, the insulating portion 116 may not be provided. The insulating portion 116 may be interpreted as air.

As shown in FIGS. 1 and 3, the guide portion 117 is formed with a bend gain portion 166 interposed therebetween. The guide portion 117 can sandwich the bending gain portion 166 from the side (from a direction orthogonal to the thickness direction of the active layer 106). The guide portion 117 can be rephrased as, for example, a side guide portion or a side cladding portion. As shown in FIG. 3, for example, the contact layer 110, the second cladding layer 108, the bending gain portion 166, the first cladding 104, and a part of the substrate 102 constitute a columnar portion 113, and the guide portion 117 is a columnar portion. It is formed on the side of 113. Although not shown, the columnar portion 113 may be constituted by, for example, the contact layer 110, the second cladding layer 108, the bending gain portion 166, and the first cladding 104. The guide part 117 can be in contact with the side surface of the columnar part 113. For example, the upper surface of the guide portion 117 is continuous with the upper surface of the contact layer 110. As the guide portion 117, an insulating material can be used, and more specifically, a SiN layer or the like can be used. The guide portion 117 may include an insulating material having a high refractive index, such as a Ta ₂ O ₅ layer. When these materials are used as the guide part 117, the current between the electrodes 112 and 114 can flow through the columnar part 113 sandwiched between the guide parts 117, avoiding the guide part 117. The guide part 117 may have a refractive index smaller than that of the active layer 106. In this case, the effective refractive index of the vertical cross section of the portion where the guide portion 117 is formed is smaller than the effective refractive index of the vertical cross section of the portion where the guide portion 117 is not formed, that is, the portion where the columnar portion 113 is formed.

  Here, the relative refractive index difference Δ with respect to the guide portion 117 of the active layer 106 (bending gain portion 166) satisfies the following formula (1).

0.05 [% / μm] ≦ (Δ / W) (1)
However, W is 5 μm or more, R is 1600 μm or more, and Δ is represented by the following formula (2).

Δ = (n _core ² −n _clad ² ) / n _core ² (2)
Here, n _core is an effective refractive index of the vertical section of the multilayer structure 120 including the bending gain portion 166, and n _clad is an effective refractive index of the vertical section of the multilayer structure 120 including the guide portion 117. Thereby, light can be efficiently confined in the bending gain portion 166 in the planar direction (direction orthogonal to the thickness direction of the active layer 106). The reason will be described later.

  As shown in FIGS. 2 and 3, the first electrode 112 is formed on the entire lower surface of the substrate 102. The first electrode 112 can be in contact with a layer that is in ohmic contact with the first electrode 112 (the substrate 102 in the illustrated example). The first electrode 112 is electrically connected to the first cladding layer 104 via the substrate 102. The first electrode 112 is one electrode for driving the light emitting element 100. As the first electrode 112, for example, a layer in which a Cr layer, an AuGe layer, a Ni layer, and an Au layer are stacked in this order from the substrate 102 side can be used. Note that a second contact layer (not shown) is provided between the first cladding layer 104 and the substrate 102, the second contact layer is exposed by dry etching or the like, and the first electrode 112 is placed on the second contact layer. It can also be provided. Thereby, a single-sided electrode structure can be obtained. This form is particularly effective when the substrate 102 is insulative.

  The second electrode 114 is formed on the contact layer 110. More specifically, the second electrode 114 is formed in the opening of the insulating part 116. Further, the second electrode 114 may be provided on the insulating part 116 and the guide layer 117. The second electrode 114 is electrically connected to the second cladding layer 108 via the contact layer 110. The second electrode 114 is the other electrode for driving the light emitting element 100. As the second electrode 114, for example, a layer in which a Cr layer, an AuZn layer, and an Au layer are stacked in this order from the contact layer 110 side can be used. The contact surface between the second electrode 114 and the contact layer 110 has a planar shape similar to that of the gain regions 160 and 162, as shown in FIG.

  Although the case of the InGaAlP system has been described as an example of the light emitting element 100 according to the first embodiment, the light emitting element 100 can use any material system capable of forming a light emission gain region. As the semiconductor material, for example, an AlGaN-based, InGaN-based, GaAs-based, AlGaAs-based, InGaAs-based, InGaAsP-based, ZnCdSe-based semiconductor material can be used.

  The light emitting element 100 according to the first embodiment can be applied to a light source such as a projector, a display, a lighting device, and a measuring device.

  The light emitting device 100 according to the first embodiment has the following features, for example.

  According to the light emitting element 100, the second gain region 162 can be bent by the bending gain portion 166. The bending gain portion 166 is sandwiched between the guide portions 117 in plan view from the stacking direction of the active layer 106, and the relative refractive index difference Δ with respect to the guide portion 117 of the active layer 106 (bending gain portion 166) is expressed by the above equation. (1) can be satisfied. The guide part 117 may be a SiN layer. Thereby, the light 22 emitted from the fourth end face 176 can be made to travel in the same direction as the light 20 emitted from the second end face 172 or in a converging direction with low loss and efficiency (for the reason) Later). Therefore, a light source with high output and low etendue can be realized.

1.2. Method for Manufacturing Light-Emitting Element According to First Embodiment Next, a method for manufacturing the light-emitting element 100 according to the first embodiment will be described with reference to the drawings. 4 to 6 are cross-sectional views schematically showing the manufacturing process of the light emitting device 100. FIG.

  As shown in FIG. 4, the first cladding layer 104, the active layer 106, the second cladding layer 108, and the contact layer 110 are epitaxially grown in this order on the substrate 102. As a method for epitaxial growth, for example, MOCVD (Metal Organic Chemical Vapor Deposition) method, MBE (Molecular Beam Epitaxy) method or the like can be used.

  As shown in FIG. 5, the contact layer 110, the second cladding layer 108, the active layer 106, the first cladding layer 104, and the substrate 102 are patterned. The patterning is performed using, for example, a photolithography technique and an etching technique. Through this step, the columnar portion 113 can be formed. Next, as shown in FIG. 3, the columnar portion 111 is formed by patterning. Note that the order of forming the columnar portions 111 and 113 is not particularly limited.

  As shown in FIG. 6, the guide portion 117 is formed so as to cover the side surface of the columnar portion 113. For example, the insulating part 116 can be formed so as to cover the side surface of the columnar part 111 in the same process as the formation of the guide part 117. Specifically, first, an insulating layer (not shown) is formed above the second cladding layer 108 (including on the contact layer 110) by, for example, a CVD (Chemical Vapor Deposition) method, a coating method, or the like. Next, the upper surface of the contact layer 110 is exposed using, for example, an etching technique. Through the above steps, the guide portion 117 and the insulating portion 116 can be formed.

  As shown in FIGS. 2 and 3, the second electrode 114 is formed on the entire surface of the contact layer 110, the insulating portion 116, and the guide portion 117. Next, the first electrode 112 is formed under the lower surface of the substrate 102. The first electrode 112 and the second electrode 114 are formed by, for example, a vacuum evaporation method.

  As shown in FIG. 1, the reflection part 130 is formed on the entire surface on the first surface 105 side, and the antireflection part 132 is formed on the entire surface on the second surface 107 side. The reflection unit 130 and the antireflection unit 132 are formed by, for example, a CVD method, a sputtering method, an ion assisted deposition (Ion Assisted Deposition) method, or the like. In addition, the formation order of the electrodes 112 and 114, the reflection part 130, and the antireflection part 132 is not specifically limited.

  Through the above steps, the light-emitting element 100 can be manufactured. In other words, the light emitting device 100 that can efficiently travel the light 22 emitted from the fourth end surface 176 in the same direction as the light 20 emitted from the second end surface 172 or in a converging direction with low loss and efficiency. can do.

1.3. Next, light emitting elements 200, 300, 400, and 500 according to modifications of the first embodiment will be described with reference to the drawings. Hereinafter, in the light emitting elements 200, 300, 400, and 500 according to the modified example of the first embodiment, members having the same functions as the constituent members of the light emitting element 100 according to the first embodiment are denoted by the same reference numerals. Detailed description thereof will be omitted.

(1) Light Emitting Element According to First Modification First, a light emitting element 200 according to a first modification of the first embodiment will be described with reference to the drawings. FIG. 7 is a cross-sectional view schematically showing the light emitting element 200, and corresponds to FIG.

  In the example of the light emitting element 100, as illustrated in FIG. 3, the guide portion 117 is configured by a single layer (for example, a SiN layer). On the other hand, in the light emitting element 200, as shown in FIG. 7, the guide part 117 is comprised by the laminated body. More specifically, the guide portion 117 of the light emitting element 200 includes a first guide layer 118 that contacts the side surface of the columnar portion 113 and a second guide layer 119 that contacts the first guide layer 118. As the first guide layer 118, for example, a SiN layer can be used. As the second guide layer 119, for example, a polyimide layer can be used.

  According to the light emitting device 200, for example, it is difficult to form the guide portion 117 made of a SiN single layer in terms of film thickness (for example, to form a thick SiN layer by CVD or sputtering). When it takes time, the second guide layer 119 made of a polyimide layer can be formed by, for example, a coating method. Therefore, according to the light emitting element 200, compared with the example of the light emitting element 100, for example, it can be formed easily (in a short time).

(2) Light-Emitting Element According to Second Modification Next, a light-emitting element 300 according to a second modification of the first embodiment will be described with reference to the drawings. FIG. 8 is a cross-sectional view schematically showing the light emitting element 300, and corresponds to FIG.

  The guide portion 117 may be air as shown in FIG. According to such a light emitting element 300, compared with the example of the light emitting element 100 and the light emitting element 200, the guide part 117 can be easily formed, and compared with the case where the guide part 117 is not formed, the loss is low. In addition, the light 22 emitted from the fourth end surface 176 can be emitted in the same direction as the light 20 emitted from the second end surface 172 or in a converging direction.

(3) Light-Emitting Element According to Third Modification Next, a light-emitting element 400 according to a third modification of the first embodiment will be described with reference to the drawings. FIG. 9 is a cross-sectional view schematically showing the light emitting element 400, and corresponds to FIG.

  In the example of the light emitting element 100, as shown in FIG. 2, a refractive index difference is provided in a region where the insulating portion 116 and the insulating portion 116 are not formed, that is, a region where the columnar portion 111 is formed, and light is transmitted. The confined refractive index waveguide type has been described. On the other hand, the light emitting device 400 can be of the gain waveguide type in which the first gain region 160 becomes the waveguide region as it is without providing a refractive index difference by forming the columnar portion 111.

  In the light emitting element 400, as shown in FIG. 9, the contact layer 110 and the second cladding layer 108 do not constitute a columnar portion, and the insulating portion 116 is not formed on the side thereof. The insulating part 116 is formed on the contact layer 110 other than above the first gain region 160. That is, the insulating part 116 has an opening above the first gain region 160, and the upper surface of the contact layer 110 is exposed in the opening. The second electrode 114 is formed on the exposed contact layer 110 and the insulating portion 116. The contact surface between the second electrode 114 and the contact layer 110 has the same planar shape as the first gain region 160. In the illustrated example, the current path between the electrodes 112 and 114 is determined by the planar shape of the contact surface between the second electrode 114 and the contact layer 110, and as a result, the planar shape of the first gain region 160 is determined. Can do. Although not shown, the second electrode 114 may not be formed on the insulating portion 116 but may be formed only on the contact layer 110 above the first gain region 160.

  The first gain region 160 has been described above, but the same description can be applied to the first gain unit 163 and the second gain unit 164 of the second gain region 162.

  According to the light emitting element 300, similarly to the light emitting element 100, a plurality of outgoing lights can be made to travel in the same direction or in a converging direction with low loss and efficiency.

(4) Light-Emitting Element According to Fourth Modification Next, a light-emitting element 500 according to a fourth modification of the first embodiment will be described with reference to the drawings. FIG. 10 is a plan view schematically showing the light emitting element 500, and corresponds to FIG. In FIG. 10, the second electrode 114 is not shown for convenience.

  As shown in FIG. 10, the second gain region 162 of the light emitting device 200 may have a plurality of bending gain units 166. In the example shown in the figure, two bending gain sections 166 are provided, but the number is not particularly limited. The second gain region 162 may include a third gain unit 567 positioned between the two bent gain units 166. The third gain section 567 is linearly provided from one bending gain section 166 (166a) to the other bending gain section 166 (166b). In the illustrated example, the third gain unit 567 is provided in a direction parallel to the perpendicular P of the first side surface 105. One bending gain unit 166 a is connected to the first gain unit 163 and the third gain unit 567. The other bending gain unit 166 b is connected to the second gain unit 164 and the third gain unit 567.

  According to the light emitting element 400, similarly to the light emitting element 100, a plurality of outgoing lights can be advanced in the same direction or in a converging direction with low loss and efficiency.

1.4. Experimental Example of Light-Emitting Element According to First Embodiment Next, an experimental example of the light-emitting element according to the first embodiment will be described with reference to the drawings. Specifically, the simulation in the model M that models the second gain region 162 of the light emitting device 100 according to the first embodiment will be described.

(1) Configuration of Model M First, the configuration of the model M will be described. FIG. 11 is a plan view schematically showing a model M of the light emitting device 100 according to the first embodiment. In the simulation, as shown in FIG. 11, the light 12 having the intensity I ₁₂ incident on the bending gain unit 166 is generated in the first gain unit 163, and the light in the second gain unit 164 emitted from the bending gain unit 166 is generated. The intensity I _{14 of the} light 14 was monitored. In the model M, for convenience of calculation, it is assumed that light does not receive gain in the second gain region 162. Therefore, in the model M, by monitoring the intensity I _{14 of the} light 14, it is possible to calculate the loss of the light _{12 with} respect to the intensity I ₁₂ (loss due to the light bending and traveling through the gain unit 166).

  The simulation was performed by a two-dimensional FDTD (Finite Difference Time Domain) method. In the model M, the effective refractive index in the vertical section of the second gain region 162 is 3.3463, and the region (for example, the insulating portion 116) between the first gain portion 163 and the second gain portion 164 of the second gain region 162 is sandwiched. The effective refractive index of the vertical cross section was 3.3440. In the model M, simulation was performed for the case where the width W of the second gain region 162 (bending gain portion 166) was 5 μm and 10 μm.

  In such a model M, two types of simulations (first simulation and second simulation) were performed.

(2) First Simulation First, the result of the first simulation will be described. FIG. 12 is a graph showing the results of the first simulation. In the first simulation, a value (Δ / W [%] obtained by dividing the relative refractive index difference Δ (the relative refractive index difference of the bending gain portion 166 with respect to the guide portion 117) by the width W of the second gain region 162 (the bending gain portion 166). / Μm]) and the intensity ratio I _R (ratio of the intensity I ₁₄ of the light 14 to the intensity I ₁₂ of the light ₁₂ , I _R = I ₁₄ / I ₁₂ × 100 [%]). In the first simulation, the curvature radius R of the bending gain unit 166 is 1600 μm.

As shown in FIG. 12, the intensity ratio _{I R} is, delta / W is at 0.05 [% / μm] or higher showed 80% or more. That is, it can be said that Δ / W is 0.05 [% / μm] or more, and the light loss in the bending gain section 166 can be reduced. As in W = who 10μm is W = 5 [mu] m than the intensity ratio _{I R} is large, generally, as the value of W is large, the value of the intensity ratio _{I R} increases. This is because the second gain region 162 has a higher effective refractive index than the guide portion 117, and the light propagating through the second gain region 162 propagates while repeating total reflection with the guide portion 117, and the value of W is The larger the component, the smaller the wave number in the direction crossing the gain region (in the horizontal plane, the direction perpendicular to the propagation direction) (they are almost inversely proportional to W in the same mode). It is because it becomes difficult to be influenced by the bending of the.

Therefore, W = 5 [mu] m or more and, in delta / W is 0.05 [% / μm] or more, the intensity ratio _{I R} can achieve 80% or more, to reduce the light loss at the curved gain section 166 be able to.

(3) Second Simulation Next, the result of the second simulation will be described. FIG. 13 is a graph showing the results of the second simulation. In the second simulation, the radius of curvature R of the curved gain section 166, and the intensity ratio I _R, a relationship was calculated. In FIG. 13, when the guide part 117 is made of an SiN layer (for example, the light emitting element 100 (see FIG. 3)), when the guide part 117 is made of air (for example, the light emitting element 300 (see FIG. 8)), the guide When the portion 117 is not provided (for example, when the cross-sectional view taken along the line III-III in FIG. 1 is FIG. 2, that is, when the bending gain portion 166 is not sandwiched between insulating layers) went. In FIG. 13, these three configurations are denoted as “guide portion SiN”, “guide portion Air”, and “no guide portion”, respectively.

As shown in FIG. 13, the intensity ratio _{I R} is a "guide portion SiN", "guide unit Air", the radius of curvature R is in the case of more than 1600 .mu.m, it showed more than 80%. In the case of “no guide portion”, the curvature radius R was 5% or less even when the curvature radius R was 1600 μm or more. In the case of “without guide portion”, the difference between the refractive index of the bending gain portion 166 and the refractive index of the active layer 106 that does not constitute the bending gain portion 166 is small, so that the bending gain portion 166 travels. This is because the loss of light increases. In addition, the “guide part Air” has a larger refractive index difference between the bending gain part 166 and the guide part 117 than the “guide part SiN” (the refractive index of air is 1.0 and the refractive index of SiN is 2.1) For example, when the light is incident from the first gain unit 163 to the curved gain unit 166, the reflected light may increase. As described above, the light travels between the gain region 162 and the guide portion 117 while repeating total reflection, and propagates in a state where the evanescent component oozes out to the guide portion 117. Therefore, the evanescent component may be reflected due to the difference in refractive index between the insulating portion 116 and the guide portion 117, resulting in a loss. Therefore, the “guide portion SiN” may be able to suppress light loss more than the “guide portion Air” (for example, when W = 10 μm shown in FIG. 13).

  The value of Δ / W of “guide part SiN, W = 5 μm” shown in FIG. 13 is 6.062 [% / μm], and Δ / W of “guide part SiN, W = 10 μm” is 3.031 [% / μm], Δ / W of “guide portion Air, W = 5 μm” is 9.107 [% / μm], and Δ / W of “guide portion Air, W = 10 μm”. Is 4.553 [% / μm].

As described above, the relative refractive index difference Δ of the active layer 106 (bending gain portion 166) with respect to the guide portion 117 is 0.05 [% / μm] ≦ (Δ / W), W is 5 μm or more, and R is 1600 μm or more. , the intensity ratio I _R becomes 80% or more, small loss of light in the gain section 166 bends, it was found that light efficiently can be emitted.

  Note that the light emitting element 100 (model M) has a configuration in which the bending gain portion 166 is sandwiched between the guide portions 117 in plan view from the stacking direction of the active layer 106. On the other hand, when the entire gain regions 160 and 162 are sandwiched between the guide portions 117 as well as the bending gain portion 166, the radiation pattern and radiation angle of the emitted light are deteriorated. As described above, the light propagating through the gain region propagates while repeating total reflection with the guide unit, and the bending gain unit 166 has other gain regions so that it is easy to be totally reflected even if it is bent. The effective refractive index of the guide portion 117 is made smaller than that of the insulating portion 116 sandwiching the gap. That is, if the effective refractive index of the guide portion 117 is used, even if the wave number in the direction crossing the gain region (in the horizontal plane and in the direction perpendicular to the propagation direction) has a larger value, that is, in the higher order mode. It is possible to propagate. In other words, higher-order modes propagate when the entire gain regions 160 and 162 are sandwiched between the guide portions 117. Therefore, the radiation pattern is significantly deteriorated and the radiation angle is increased.

2. Second Embodiment Next, a projector 700 according to a second embodiment will be described with reference to the drawings. FIG. 14 is a diagram schematically showing the projector 700. In FIG. 14, for convenience, the casing that configures the projector 700 is omitted.

  In the projector 700, as shown in FIG. 14, a red light source (light emitting device) 600R, a green light source (light emitting device) 600G, and a blue light source (light emitting device) 600B that emit red light, green light, and blue light are included in the present invention. The light emitting device 600 includes the light emitting element (for example, the light emitting element 100).

  Here, FIG. 15 is a cross-sectional view schematically showing the light emitting device 600. As shown in FIG. 15, the light emitting device 600 can include, for example, a light emitting element 100, a base 610, and a submount 620. For example, the base 610 can indirectly support the light emitting element 100 via the submount 620. As the base 610, for example, a plate-shaped (cuboid shape) member can be used. Examples of the material of the base 610 include ceramics, copper, and aluminum. The base 610 may function as a heat sink, for example. The base 610 may be a Peltier element, for example. The submount 620 is provided on the base 610 and supports the light emitting element 100. The submount 620 can be made of a conductive material such as copper or aluminum, for example. Thereby, a voltage can be supplied to the electrodes 112 and 114 of the light emitting element 100. The light emitting element 100 is supported on the base 610 between the submounts 620. In the illustrated example, two light emitting elements 100 are arranged in the thickness direction of the light emitting element 100 (thickness direction of the active layer 106), but the arrangement direction and the number thereof are not particularly limited. The plurality of light emitting elements 100 can emit light 20 and 22 in the same direction, for example.

  As shown in FIG. 14, the projector 700 includes transmissive liquid crystal light valves (light modulation devices) 704R, 704G, and 704B that modulate light emitted from the light sources 600R, 600G, and 600B in accordance with image information, and liquid crystal. A projection lens (projection device) 708 that magnifies and projects an image formed by the light valves 704R, 704G, and 704B onto a screen (display surface) 710; In addition, the projector 700 can include a cross dichroic prism (color light combining means) 706 that combines the light emitted from the liquid crystal light valves 704R, 704G, and 704B and guides the light to the projection lens 708.

  Further, in order to make the illuminance distribution of the light emitted from the light sources 600R, 600G, and 600B uniform, the projector 700 includes the uniformizing optical systems 702R, 702G, and 702B on the downstream side of the light paths from the light sources 600R, 600G, and 600B. The liquid crystal light valves 704R, 704G, and 704B are illuminated with light that has been provided with a uniform illuminance distribution. The uniformizing optical systems 702R, 702G, and 702B are configured by, for example, a hologram 702a and a field lens 702b.

  The three color lights modulated by the liquid crystal light valves 704R, 704G, and 704B are incident on the cross dichroic prism 706. This prism is formed by bonding four right-angle prisms, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are arranged in a cross shape on the inner surface thereof. These dielectric multilayer films combine the three color lights to form light representing a color image. The synthesized light is projected onto the screen 710 by the projection lens 706 that is a projection optical system, and an enlarged image is displayed.

  According to the projector 700, it is possible to have the light emitting element 100 capable of traveling the light 20, 22 in the same direction or the focusing direction with low loss, and to realize a light source with high output and low etendue. it can. Therefore, the projector 700 can be reduced in size and increased in luminance.

  In the above example, a transmissive liquid crystal light valve is used as the light modulation device. However, a light valve other than liquid crystal may be used, or a reflective light valve may be used. Examples of such a light valve include a reflective liquid crystal light valve and a digital micromirror device. Further, the configuration of the projection optical system is appropriately changed depending on the type of light valve used.

  Further, the light emitting device 600 scans the light from the light emitting device 600 on the screen so that the light emitting device 600 has a scanning unit that is an image forming device that displays an image of a desired size on the display surface. The present invention can also be applied to a light source device of a device (projector).

10 light, 12 light, 14 light, 20 light, 22 light, 100 light emitting element,
102 substrate, 104 first cladding layer, 105 first surface, 106 active layer,
107 second surface, 108 second cladding layer, 110 contact layer, 111 columnar portion,
112 first electrode, 113 columnar part, 114 second electrode, 116 insulating part,
117 guide portion, 118 first guide layer, 119 second guide layer,
120 laminated structure, 130 reflection portion, 132 antireflection portion, 160 first gain region,
162 second gain region, 163 first gain unit, 164 second gain unit,
166 bending gain section, 168 gain region pair, 170 first end face, 172 second end face,
174 3rd end surface, 176 4th end surface, 178 overlapping surface, 200 light emitting element,
300 light emitting elements, 400 light emitting elements, 500 light emitting elements, 567 third gain section,
600 light emitting device, 610 base, 620 submount, 700 projector,
702 homogenizing optical system, 702a hologram, 702b field lens,
704 Liquid crystal light valve, 706 Cross dichroic prism,
708 projection lens, 710 screen

Claims (8)

A laminated structure having a first cladding layer, a second cladding layer, and an active layer sandwiched between the first cladding layer and the second cladding layer;
At least a part of the active layer constitutes a first gain region and a second gain region serving as a current path of the active layer,
In the laminated structure, the first surface and the second surface of the exposed surfaces of the active layer are in a positional relationship facing each other.
In the wavelength band of light generated in the first gain region and the second gain region, the reflectance of the first surface is higher than the reflectance of the second surface,
The first gain region and the second gain region are provided from the first surface to the second surface,
The end surface on the first surface side of the first gain region and the end surface on the first surface side of the second gain region overlap on the first surface,
The first gain region is provided in a straight line, as viewed in plan from the stacking direction of the active layer, and inclined in a clockwise direction with respect to the normal of the first surface;
The second gain region is a plan view from the stacking direction of the active layer,
A first gain section provided linearly from the first surface and inclined in a counterclockwise direction with respect to a perpendicular to the first surface;
A bending gain portion having a width W and a radius of curvature R connected to the first gain portion;
Have
The bending gain portion is sandwiched between guide portions having a refractive index smaller than that of the active layer in plan view from the stacking direction of the active layer,
The relative refractive index difference Δ with respect to the guide portion of the active layer satisfies the following formula (1):
The light emitted from the end surface on the second surface side of the first gain region and the light emitted from the end surface on the second surface side of the second gain region travel in the same direction or in a converging direction. , Light emitting element.
0.05 [% / μm] ≦ (Δ / W) (1)
However, W is 5 μm or more, R is 1600 μm or more, and Δ is represented by the following formula (2).
Δ = (n _core ² −n _clad ² ) / n _core ² (2)
Here, n _core is an effective refractive index of the vertical section of the multilayer structure including the bending gain portion, and n _clad is an effective refractive index of the vertical section of the multilayer structure including the guide portion. In claim 1,
The light emitting element whose said guide part is a SiN layer. In claim 1,
The guide part is a laminate of a SiN layer and a polyimide layer,
The light emitting device, wherein the bending gain portion is in contact with the SiN layer. In claim 1,
The light emitting element in which the guide part is air. In any one of Claims 1 thru | or 4,
The second gain region is a plan view from the stacking direction of the active layer,
A light emitting device further comprising: a second gain portion that is provided in a straight line from the bending gain portion to the second surface and inclined in a clockwise direction with respect to a normal to the first surface. In any one of Claims 1 thru | or 5,
The second gain region has a plurality of bending gain portions. In any one of Claims 1 thru | or 6,
The light-emitting element, wherein the bending gain portion has an arc shape in plan view from the stacking direction of the active layer. A light emitting device comprising the light emitting element according to any one of claims 1 to 7,
A light modulation device that modulates light emitted from the light emitting device according to image information;
A projection device for projecting an image formed by the light modulation device;
Including projector.

Images